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  • IJSRES Internat ional Journal of Scient if ic Research in Environmental Sciences

    www.i jsrpub.com

    August 2013

    Volume 1, Issue 8

    Pages 166 216

  • Table of Contents

    Article Author(s) page Inhibitive Effect of Some Natural Naphthenates as Corrosion Inhibitors on the Corrosive Performance of Carbon Steel in CO2-Saturated Brine

    Vagif M. Abbasov, Hany M. Abd El-Lateef, Sevinc A. Mamedxanova, Leylufer. I. Aliyeva, Teyyub A. Ismayilov, Musayev J. Ilham, Orkhan A. Aydamirov, Fariz A. Amirov

    166

    Livestock Products and Environment Maryam Asghari 179

    Host Preference and Performance of Fruit Flies Bactrocera zonata (Saunders) and Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae) For Various Fruits and Vegetables

    Muhammad Sarwar, Muhammad Hamed, Bilal Rasool, Muhammad Yousaf, Mureed Hussain

    188

    The Inhibitory Properties of Organic Pest Control Agents against Aphid (Aphididae: Homoptera) on Canola Brassica napus L. (Brassicaceae) Under Field Environment

    Muhammad Sarwar 195

    A Review of Genetic and Epigenetic Mechanisms in Heavy Metal Carcinogenesis: Nickel and Cadmium

    Zienab Saedi, Shahin Gavanji, Sahar Davodi

    202

  • International Journal of Scientific Research in Environmental Sciences (IJSRES), 1(8), pp. 166-178, 2013 Available online at http://www.ijsrpub.com/ijsres

    ISSN: 2322-4983; 2013 IJSRPUB

    http://dx.doi.org/10.12983/ijsres-2013-p166-178

    166

    Full Length Research Paper

    Inhibitive Effect of Some Natural Naphthenates as Corrosion Inhibitors on the

    Corrosive Performance of Carbon Steel in CO2-Saturated Brine

    Vagif M. Abbasov1, Hany M. Abd El-Lateef

    1, 2*, Sevinc A. Mamedxanova

    1, Leylufer. I. Aliyeva

    1, Teyyub A.

    Ismayilov1, Musayev J. Ilham

    1, Orkhan A. Aydamirov

    1, Fariz A. Amirov

    1

    1Mamedaliev Institute of Petrochemical Processes, National Academy of Sciences of Azerbaijan, AZ1025 Baku, Azerbaijan

    2Chemistry Department, Faculty of Science, Sohag University, 82524 Sohag, Egypt

    *Corresponding Author: [email protected]

    Received 26 April 2013; Accepted 07 June 2013

    Abstract. Two surfactants [sodium and potassium salts of naphthenic acids] were synthesized by liquid-phase oxidation

    process of the naphtha fraction of the Baku crude oil and their chemical structure was confirmed by FT-IR spectroscopy. The

    surface tension at 298K was measured; the critical micelle concentration (CMC) and some surface active parameters were

    calculated. The inhibition efficiency (%) of these surfactants has been studied by both Linear polarization resistance corrosion

    rate and Potentiodynamic polarization measurements at 50 C. The data showed that, the presence of investigated inhibitors

    results a high decrease in the corrosion rate. The inhibition efficiency increases with an increase in the inhibitor dose, getting

    maximum inhibition efficiency 99.48% at 100 ppm of potassium salt. The Tafel polarization results indicate that the inhibitors

    act as mixed inhibitors. Tafel slopes are approximately constant and independent on the inhibitor concentration. The adsorption

    of the inhibitors on the carbon steel surface obeys Langmuirs adsorption isotherm. The thermodynamic parameters of

    adsorption revealed a strong interaction between the inhibitors and the corroding carbon steel surface.

    Key words: Petroleum acids, Carbon Steel, surfactants, corrosion inhibition, Carbon Dioxide Corrosion.

    1. INTRODUCTION

    Corrosion of carbon steel is a significant problem in

    the oil and gas production and transportation systems

    and causes significant economic loss (Okafor et al.,

    2009). CO2 corrosion of carbon steels has been one of

    the most common corrosion problems in oil and gas

    industry. Carbon dioxide dissolves in the presence of

    a water phase, forming carbonic acid, which is

    corrosive to carbon steel (Lopez et al., 2003a). The

    understanding of CO2 corrosion mechanisms under

    the effects of many mechanical and environmental

    factors, such as flow, temperature, pressure, oilwater

    ratio, pH, solution chemistry, and corrosion product

    layer, has been of great concern in corrosion field

    (Yin et al., 2009).

    The use of inhibitors is one of the most practical

    methods for protection against corrosion. The

    inhibitors, which reduce corrosion on metallic

    materials, are inorganic inhibitors, organic inhibitors,

    surfactant inhibitors and mixed material inhibitors. Surfactants are special type of organic compounds and

    exhibit unique properties due to their amphiphilic

    molecule. This is the reason of their wide application

    in the field of inhibition of metals against corrosion. A

    molecular layer of surfactants is formed as a result of

    this attraction with the construction of a hydrophobic

    barrier, which prevent the contact of the metal surface

    with the environment. The surfactant inhibitors have

    many advantages such as high inhibition efficiency,

    low price, low toxicity and easy production (Abbasov

    et al., 2013a; Abbasov et al., 2013b; Abd El-Lateef et

    al., 2012a; Stoyanova et al., 1997; Abdallah et al.,

    2009; Joseph and Rajendran, 2001). The adsorption of

    the surfactant on the metal surface can markedly

    change the corrosion-resisting property of the metal

    (Abd El-Lateef et al., 2012b), and so the study of the

    relationship between the adsorption and corrosion

    inhibition is of great importance.

    Salts of naphthenic acids, which are naphthenates,

    are widely used as hydrophobic sources of metal ions

    in diverse applications. Metal naphthenates

    are coordination complexes. They have the formula

    M(naphthenate)2 or are basic oxides with the formula

    M3O(naphthenate)6. The naphthenates are highly

    soluble in organic media, such as paints. They have

    industrial applications including

    synthetic detergents, lubricants and corrosion

    inhibitors (Nora et al., 2005).

    In this study, two surfactants (sodium and

    potassium salts of naphthenic acids) were synthesized

    by liquid-phase oxidation process of

    the naphtha fraction of the Baku crude oil. The surface

    activities of these surfactants were determined. The

    applicability of these surfactants as corrosion

    inhibitors for carbon steel were estimated by Linear

    polarization resistance corrosion rate and

    mailto:[email protected]://en.wikipedia.org/wiki/Naphthahttp://en.wikipedia.org/wiki/Crude_oilhttp://en.wikipedia.org/wiki/Coordination_complexhttp://en.wikipedia.org/wiki/Detergenthttp://en.wikipedia.org/wiki/Lubricanthttp://en.wikipedia.org/wiki/Naphthahttp://en.wikipedia.org/wiki/Crude_oil

  • Abbasov et al.

    Inhibitive Effect of Some Natural Naphthenates as Corrosion Inhibitors on the Corrosive Performance of Carbon Steel

    in CO2-Saturated Brine

    167

    Potentiodynamic polarization measurements in CO2-

    saturated 1% NaCl solution at 50 C.

    2. MATERIALS AND METHODS

    2.1. Chemical composition of carbon steel alloy

    The rotating disk working electrodes for tests were

    made of carbon steel grade 080A15 and have an area

    of 4.55 cm2

    with a chemical composition (wt%) C

    0.18%, Si 0.17%, Mn 0.70%, P 0.011%, S 0.03%, Ni

    0.0%, Cr 0.01% and Fe balance. The data was

    provided by European Corrosion Supplies Ltd

    2.2. Synthesis of Surfactant inhibitors

    The surfactants used as inhibitors were synthesized in

    our laboratory based on petroleum acids. The new

    series of the complex surfactants were synthesized

    from naphthenic acids isolated from light oil fractions

    (Tb= 180-350 C) (Abbasov et al, 2012c). Two types

    from inhibitors were synthesized in high purity by the

    following compositions: [R-COONa (I) and R-COOK

    (II)]. The chemical structure of the synthesized

    surfactants was characterized by using FT-IR,

    Spectrum BX spectrometer using KBr disks.

    2.3. Preparation of solutions

    The aggressive solution, 1% NaCl, was prepared by

    dissolving of analytical grade NaCl in distilled water.

    The concentration range of the prepared surfactants

    was from 25 to 100 ppm used for corrosion

    measurements. All inhibitors solutions were prepared

    using distilled water.

    2.4. Corrosion measurements

    The measurements were performed on the rotating

    cylinder electrode. This electrode was used for one

    time. The reference electrode was Ag/AgCl Electrode

    to which all potentials are referred.

    Before beginning the experiment, the prepared 1%

    - of sodium chloride solution was stirred by a

    magnetic stirrer for 60 min in 1000 ml cell. Then this

    cell was thermostated at 50 C for 1 hour under a CO2

    pressure of 0.9 bars. The solution was saturated with

    carbon dioxide. To remove any surface contamination

    and air formed oxide, the working electrode was kept

    at1500 mV (Ag/AgCl) for 5 min in the tested

    solution, disconnected shaken free of adsorbed

    hydrogen bubbles and then cathodic and anodic

    polarization was recorded. ACM Gill AC instrument

    connected with a personal computer was used for the

    measurements.

    2.4.1. Potentiodynamic polarization measurements

    The extrapolation of cathodic and anodic Tafel lines

    was carried out in a potential range 100 mV with

    respect to corrosion potential (Ecorr) at scan rate of 1

    mV/s.

    2.4.2. Linear polarization resistance corrosion rate

    The LPR method is ideal for plant monitoring offering

    an almost instantaneous indication of corrosion rate,

    allowing for quick evaluation of remedial action and

    minimizing unscheduled downtime. The prepared 1%

    - of the solution sodium chloride was stirred by a

    magnetic stirrer for 60 min in 4000 ml. The prepared

    solution poured into the 4 glass beakers (1000 ml for

    each one). Then these beakers were placed on a heater

    at 50 C for 1 hour under a pressure of 0.9 bars. The

    solution was saturated with carbon dioxide. After

    that, the electrodes were placed in the medium and are

    connected through a potentiometer ACM GILL AC.

    The surface of working electrode is cleaned by

    acetone before using, these electrodes are using for

    one time. After 1 hour, except for 1 beaker, the

    remaining 3 is fed with the suitable amount of

    inhibitor and continued supply of CO2 under pressure

    of 0.9 bar until the end of the experiment.

    The potential of the working electrode was varied

    by a CoreRunning programme (Version 5.1.3.)

    through an ACM instrument Gill AC. The

    CoreRunning programme converts a corrosion current

    in mA/cm2 to a corrosion rate in mm/year. A

    cylindrical carbon steel rod of the composition

    080A15 GRADE STEEL was used as a working

    electrode. Gill AC technology allows measure DC and

    AC signals using standard Sequencer software. A

    small sweep from typically 10 mV to +10 mV at 10

    mV/min around the rest potential is performed.

    2.5. Surface tension measurements

    The surface tensions were determined by DuNouy

    Tensiometer, Kruss Type 8451 and the temperature

    was maintained precisely at 25 C. Critical micelle

    concentration (CMC) values of surfactants were

    determined, according to the break points in plots of

    the surface tension versus ln molar concentration of

    investigated surfactants.

    3. RESULTS AND DISCUSSION

    3.1. Chemical structure of the synthesized

    surfactants

    The FT-IR spectrum of the naphthenic acid, shows a

    broad OH stretch found at 3200-2700 cm-1

    ; the strong

  • International Journal of Scientific Research in Environmental Sciences (IJSRES), 1(8), pp. 166-178, 2013

    168

    signal at 1712 cm-1

    was due to a carbonyl group

    (C=O). The strong signal at 1289 cm-1

    was due to a C-

    O stretch; the signal at 1369 cm-1

    was due to a C-O-H.

    The FT-IR absorption spectra of inhibitor II

    confirmed that, the disappearance of OH band of acid

    (broad band), this confirmed that, the replacement of

    H atom in carboxylic group by K atom to form

    COOK. FTIR spectra confirmed the expected

    functional groups in the synthesized anionic

    surfactant.

    3.2. LPR corrosion rate

    The linear- polarization-resistance (LPR) corrosion

    rate bubble-test method involves evaluating the

    corrosion of a given metal in simulated brine saturated

    with CO2 at a temperature equivalent to that in the

    field. During the test, CO2 gas is sparged continuously

    into the test solution. The rate of corrosion is

    determined instantaneously with the LPR corrosion

    rate technique, in which a small direct-current voltage

    is applied to a pair of identical electrodes and the

    resultant current is measured.

    Figure 1 shows that, the change in corrosion rate

    (CR) with time for carbon steel in CO2-saturated 1%

    NaCl solution containing different concentrations

    form inhibitor II (K-salt) at 50 C. The inhibitor was

    added after 1 hour of exposure because at this time the

    corrosion potential got stable, allowing the

    measurement of the CR prior the injection of the

    inhibitor. The initial corrosion rate, without inhibitor,

    was measured to be between 3.45 and 5.03 mm y-1

    . It

    can be observed from Figure 1 that, the CR, in the

    absence of inhibitor, tends to increase with time. The

    increase in CR has been attributed to the galvanic

    effect between the ferrite phase and cementite (Fe3C)

    which is a part of the original steel in the non-oxidized

    state and accumulates on the surface after the

    preferential dissolution of ferrite (-Fe) into Fe2+

    (Staicopolus, 1963). Fe3C is known to be less

    active than the ferrite phase. Therefore, there is a

    preferential dissolution of ferrite over cementite,

    working the former as the anode and latter as the

    cathode, favoring the hydrogen evolved reaction

    (HER) during the corrosion process (Crolet et al.,

    1998; Videm et al., 1996).

    Variation of the corrosion rate for inhibitor II at

    different concentrations is presented in Figure 1.

    Corrosion parameters were calculated on the basis of

    LPR corrosion rate test. The inhibition efficiency (

    %) and surface coverage () were calculated

    according to the following equations:

    where CRo is the corrosion rate without inhibitor

    and CRi is the corrosion rate when inhibitor is present.

    It can be seen that the presence of inhibitors results a

    high decrease in the rate of corrosion. In the case of

    these inhibitors, the corrosion rate decreases as the

    inhibitor concentration increases, getting maximum

    inhibition efficiency ranged between 98.49 and

    99.48% at 100 ppm after 20 hour of exposure (Table

    1). This trend may results from the fact that

    adsorption and surface coverage increase with the

    increase in concentration; thus the surface is

    effectively separated from the medium (El-Sayed et

    al., 2010).

    Table 1 shows the calculated values of corrosion

    rates, the inhibition efficiencies and the surface

    coverage in the absence and presence of different

    concentrations of different inhibitors at 50 C. A

    general trend is observed in presence of the studied

    inhibitors, a decrease in the corrosion rate of carbon

    steel in presence of these surfactants compared to the

    blank (inhibitor free solution). By increasing the

    concentration of the surfactants, a further decrease in

    corrosion rate of carbon steel was observed. The

    maximum inhibition efficiency (%) was obtained at

    100 ppm of inhibitors.. This indicates that the

    inhibitory action of the inhibitors against carbon steel

    corrosion can be attributed to the adsorption of these

    molecules on the metal surface, limits the dissolution

    of carbon steel, and the adsorption amounts of

    surfactants on carbon steel increase with

    concentrations in the corrosive solutions (Taleb and

    Mohamed, 2011).

    Figure 2 shows the variation of the corrosion rate

    with time for carbon steel in CO2-saturated brine

    containing 100 ppm from different surfactants at 50

    C. This plot indicates that, the presence of different

    inhibitors decreases the rate of corrosion. The data

    indicate that, the inhibition efficiency of carbon steel

    in CO2-saturated brine in the presence of inhibitor II

    (K-salt) more than that obtained of inhibitor I (Na-

    salt).

    The high inhibition efficiency obtained in CO2-

    saturated solution in the presence of studied inhibitors

    can be attributed to the formation of a protective film

    of iron carbonate (FeCO3) as follows (Lopez et al.,

    2003b):

  • Abbasov et al.

    Inhibitive Effect of Some Natural Naphthenates as Corrosion Inhibitors on the Corrosive Performance of Carbon Steel

    in CO2-Saturated Brine

    169

    The anodic dissolution for iron in carbonic acid

    solutions gives ferrous ions (Ogundele and White,

    1986).

    Fe Fe2+

    + 2e- (7)

    According to these processes, a corrosion layer

    was formed on the steel surface. The properties of the

    formed layers and its effect on the corrosion rate are

    important factors to take into account when studying

    the corrosion of steels in CO2 environments. Ogundele

    and White suggested that, iron carbonate, FeCO3, may

    be important in the formation of protective layers on

    steel surface (Ogundele and White, 1986). The

    formation of iron carbonate can be explained by using

    the following Eq. (Migahed et al, 2006).

    Fe2+

    +2

    3CO FeCO3 (8)

    3.3. The extrapolation of cathodic and anodic Tafel

    lines

    The inhibiting effect of the synthesized compounds on

    the corrosion reaction of carbon steel in CO2-saturated

    NaCl solution was investigated using the

    electrochemical polarization method. The polarization

    technique was adopted to determine both cathodic and

    anodic polarization curves. It is also used to calculate

    the corrosion currents from the extrapolation of Tafel

    lines to pre-determined open circuit potential. This is

    achieved by measuring the potentialcurrent

    characteristics of the metal/solution system under

    consideration with the aid of a potentiostat.

    Figure 3 shows the influence of inhibitor I

    concentrations on the Tafel cathodic and anodic

    polarization characteristics of carbon steel in CO2-

    saturated solution at scan rate 1 mV/s and at 50 C.

    Corrosion parameters were calculated on the basis of

    cathodic and anodic potential versus current density

    characteristics in the Tafel potential region (Tremont

    et al, 2000; Schultze and Wippermann, 1987). Steady

    state of open circuit corrosion potential (Ecorr) for the

    investigated electrode in the absence and presence of

    the studied inhibitor was attained after 4560 min

    from the moment of immersion. Corrosion current

    density (Icorr) of the investigated electrodes was

    determined (El-Sayed, et al, 2011), by extrapolation of

    cathodic and anodic Tafel lines to corrosion potential

    (Ecorr). The inhibition efficiency expressed as percent

    inhibition (%) is defined as:

    Where Iuninh. and Iinh. are the uninhibited and

    inhibited corrosion currents. The inhibited corrosion

    currents are those determined in the presence of the

    studied surfactants used in this investigation. The

    uninhibited corrosion currents were determined in

    pure (inhibitor free) CO2-saturated 1% NaCl solution

    at the same temperature. It can be seen that the

    presence of surfactants molecule results a marked

    shift in both cathodic and anodic branches of the

    polarization curves towards lower current densities.

    This means that, the inhibitors affect both cathodic

    and anodic reactions. It was found that, both anodic

    and cathodic reactions of carbon steel electrode

    corrosion were inhibited with increasing concentration

    of synthesized inhibitors. These results suggest that

    not only the addition of synthesized inhibitors reduce

    anodic dissolution but also retard the hydrogen

    evolution reaction.

    The electrochemical parameters Ecorr, Icorr,

    inhibition efficiency (%), anodic and cathodic Tafel

    slopes (a , c) obtained from the polarization

    measurements were listed in Table 2. The data

    exhibited that, the corrosion current density (Icorr)

    decreases, and the inhibition efficiency (%) increases

    as the concentration of inhibitors is increased. These

    results suggest that retardation of the electrodes

    processes occurs, at both cathodic and anodic sites, as

    a result of coverage of these sites by surfactants

    molecules. The results also indicate that, the

    percentage inhibition efficiency ( %) of the inhibitor

    (II) is greater than that of the inhibitor (I), thereby;

    firmly agree with aforementioned results of LPR

    corrosion rate.

  • International Journal of Scientific Research in Environmental Sciences (IJSRES), 1(8), pp. 166-178, 2013

    170

    Fig. 1: Variation of the Corrosion rate with time for carbon steel in CO2-saturated 1 % NaCl solution containing different

    concentrations of inhibitor II (K-salt) at 50 C.

    Fig. 2: Variation of the Corrosion rate with time for carbon steel in CO2-saturated 1% NaCl solution containing 100 ppm of

    different inhibitors at 50 C.

    The corrosion potential Ecorr values of all

    synthesized inhibitors were shifted slightly toward

    both cathodic and anodic directions and did not show

    any definite trend in CO2-saturated brine. This may be

    considered due to the mixed-type behaviour of the

    studied inhibitors. It can be observed, the shift in Ecorr

    that is characteristic of anodic and anodic/cathodic

    inhibitor (Lpez et al, 2005). It was explained that this

    shift in Ecorr is due to active sites blocking effect that

    occurs when an inhibitor is added (Cao, 1996). In the

    case of CO2 corrosion the anodic and cathodic

    reactions are the oxidation of iron and the reduction of

    hydrogen, respectively (Nordsveen et al., 2005). If it

    is considered that the active sites on the metal surface

    are the same for both reactions before adding the

    inhibitor, it is logical the change in Ecorr when the

    inhibitor is present because its adsorption change

    those active sites and therefore the anodic and

    cathodic reaction rates (Farelas and Ramirez, 2010).

    The fact that the slopes of the cathodic (a) and

    anodic (c) Tafel lines in Table 2 remain almost

    unchanged upon addition of the inhibitors. These

    results indicate that this inhibitor acts by simply

    blocking the available surface area. In other words,

    the inhibitor decreases the surface area for corrosion

    of the investigated metal, and only causes inactivation

  • Abbasov et al.

    Inhibitive Effect of Some Natural Naphthenates as Corrosion Inhibitors on the Corrosive Performance of Carbon Steel

    in CO2-Saturated Brine

    171

    of a part of the surface with respect to corrosive

    medium. On the other hand, the cathodic Tafel slopes

    (c) are also found to be greater than the respective

    anodic Tafel slopes (a). These observations are

    correlated with the fact that the cathodic exchange-

    current density values are less than those of the anodic

    counter parts. It can be concluded that the overall

    kinetics of corrosion of carbon steel alloy in CO2

    saturated solution are under cathodic control.

    For all studied inhibitors, the common ground was

    that the corrosion current density decreased and the

    inhibition efficiency increased with increasing

    inhibitors concentration. The highest inhibition

    efficiency was 98.49 % for inhibitor II (K-salt) at100

    ppm.

    Table 1: The corrosion parameters obtained from LPR corrosion rate measurements for carbon steel electrode in CO2-

    saturated brine in the absence and presence of various concentrations of investigated surfactants at 50 C.

    Fig. 3: Tafel polarization curves for carbon steel in CO2-saturated 1% NaCl solution containing different concentration of

    inhibitor (I) at 50 C.

  • International Journal of Scientific Research in Environmental Sciences (IJSRES), 1(8), pp. 166-178, 2013

    172

    Table 2: Corrosion parameters obtained from Tafel polarization for carbon steel in CO2-saturted 1% NaCl solution

    in the absence and presence of different concentrations of the prepared surfactants at 50 C.

    3.4. Surface tension and surface active properties

    The values of surface tension () were measured at

    303 K for various concentrations of the synthesized

    surfactants. The measured values of () were plotted

    against ln of the surfactant concentration, ln C (Fig.

    4). The intercept of the two straight lines designates

    the CMC, where saturation in the surface adsorbed

    layer takes place. The plot showed that the surfactant

    was molecularly dispersed at low concentration

    leading to a reduction in surface tension. This

    reduction increases with increasing concentration. At

    high concentration, however, when a certain

    concentration was reached (CMC), the surfactant

    molecules form micelles, which were in equilibrium

    with the free surfactant molecules (Migahed et al.,

    2006).

    The surface active properties of the surfactant,

    effectiveness (cmc), maximum surface excess (max),

    and minimum area per molecule (Amin) were

    calculated using the following equations (Rosen,

    1978):

    Where /lnC is maximum slope, 0 is the surface

    tension of pure water, cmc the surface tension at

    critical micelle concentration, NA is the Avogadros

    number (6.023 1023

    molecules/mol), R is the molar

    gas constant (R= 8.314 J/(mol K)) and T is the

    absolute temperature = (tC+273), o

    micG is the Gibbs

    free energy of micellization, 0

    adsG is the Gibbs free

    energy of adsorption (Badawi et al., 2007).

    The data presented in Table 3 show some of the

    surface active properties for the investigated

    surfactants. The results indicate that, the consequent

    increase in of max leads to crowding at the interface,

    which causes a decrease in Amin values. The values of

    effectiveness (cmc) at 298 K indicate that the prepared

    compounds gives large reduction of surface tension at

    CMC, so that, these compounds acts as effective

    corrosion inhibitors for carbon steel in CO2- saturated

    1% NaCl solutions.

    The free energy changes of micellization and

    adsorption showed negative sign showing the

    spontaneity of the two processes at 25 C (Table 3).

    Moreover, 0

    adsG increase in negativity thano

    micG .

    That showed the higher tendency of these surfactants

    towards adsorption rather than micellization. Then the

    adsorption will be accompanied with micellization at

    last. The tendency towards adsorption was referred to

  • Abbasov et al.

    Inhibitive Effect of Some Natural Naphthenates as Corrosion Inhibitors on the Corrosive Performance of Carbon Steel

    in CO2-Saturated Brine

    173

    the interaction between the aqueous phases and the

    hydrophobic chains which pump the surfactant

    molecules to the interface (Alsabagh et al., 2006).

    Table 3: The critical micelle concentration and surface parameters of the synthesized surfactants

    3.5. Adsorption isotherm and thermodynamic

    parameters

    Basic information on the interaction between the

    inhibitor molecules and metal surfaces could be

    provided from the adsorption isotherms. The values of

    surface coverage () which were defined as in the

    following equation:

    A correlation between and inhibitor

    concentration in the corrosive medium can be

    represented by the Langmuir adsorption isotherm (Tao

    et al., 2009).

    Where Kads is the equilibrium constant of the

    inhibitor adsorption process and Cinh. is the inhibitor

    concentration.

    Plots of Cinh/ versus Cinh yielded a straight line as

    shown in Fig. 5, which suggested that at 323 K the

    adsorption of investigated inhibitors on metal surface

    obeyed Langmuir adsorption isotherm model. This

    isotherm assumed that the adsorbed molecules

    occupied only one site and there was no interaction

    with other molecules adsorbed. The linear regression

    coefficients (r) and the slopes parameter were shown

    in Table 4. All correlation coefficient (r > 0.997)

    indicated that the inhibition of carbon steel by studied

    surfactants was attributed to the adsorption of

    inhibitors on the metal surface. However, the slopes of

    the Cinh/ versus Cinh plots were close to 1 and

    showed a little deviation from unity which meant non-

    ideal simulating (Badawy et al., 2006) and unexpected

    from Langmuir adsorption isotherm. They might be

    the results of the interactions between the adsorbed

    species on the metal surface (Migahed et al., 2003;

    Azim et al., 1974).

    Kads values could be calculated from the intercepts

    of the straight lines on the Cinh/ -axis, the Kads was

    related to the standard free energy of adsorption, o

    adsG ; with the following equation (Flis and

    Zakroczymski, 1996):

    The value 55.5 in the above equation was the molar

    concentration of water in solution in mol/L (Azim et

    al., 1974). The relatively high value of the adsorption

    equilibrium constant (Kads; Table 4) reflects the high

    adsorption ability of these surfactants on the metal

    surface (Abd El-Lateef et al., 2012c). It is also noted

    that, the high value of Kads for inhibitor II indicate

    stronger adsorption on the carbon steel surface than

    the inhibitor I. Large values of Kads imply more

    efficient adsorption hence better inhibition efficiency

    (Refay et al., 2004).

    The high and negative values of free energy of

    adsorption (o

    adsG ) indicate spontaneous adsorption

    and strong interaction of the inhibitor molecule with

    the carbon steel surface. Generally, values of o

    adsG

  • International Journal of Scientific Research in Environmental Sciences (IJSRES), 1(8), pp. 166-178, 2013

    174

    up to -20 kJ mol-1

    are consistent with physisorption,

    while those around -40 kJ mol-1

    or higher are

    associated with chemisorption as a result of the

    sharing or transfer of electrons from organic

    molecules to the metal surface to form a coordinate

    bond (Farhat and Quraishi, 2011). In the present

    study, the o

    adsG values obtained for the surfactants I

    and II on carbon steel in CO2-saturated 1 % NaCl

    solution are -44.71 and -45.92 kJ mol-1

    , respectively.

    This indicates that the adsorption of studied inhibitors

    is typical chemisorption.

    Fig. 4: Change of surface tension () with the concentration of the surfactants at 25 C.

    Fig. 5: Langmuir plots for inhibitors I and II in CO2-saturated brine obtained from the extrapolation of cathodic and anodic

    Tafel lines at 50 C.

    4. CONCLUSION

    In this research, Linear polarization resistance

    corrosion rate and Potentiodynamic polarization

    measurements were used to study the corrosion

    inhibition of carbon steel in CO2-saturated 1% NaCl

    solution using sodium and potassium salts of

    naphthenic acids as corrosion inhibitors. The results

    can be summarized as follows.

    a) The synthesized surfactant acts as an effective

    corrosion inhibitor for carbon steel in CO2-saturated

    1% NaCl solution.

    b) The inhibition efficiency increased with

    increasing concentration of the inhibitor.

  • Abbasov et al.

    Inhibitive Effect of Some Natural Naphthenates as Corrosion Inhibitors on the Corrosive Performance of Carbon Steel

    in CO2-Saturated Brine

    175

    c) The inhibition efficiency (%) reached to 99.48

    % at 100 ppm of the inhibitor II.

    d) Polarization measurements showed that the

    inhibitors act as mixed inhibitor.

    e) The adsorption of the inhibitors on the metal

    surface obeys Langmuir adsorption isotherm.

    f) The higher value of the equilibrium adsorption

    constant (Kads. = 3.65 105) reflects the high

    adsorption ability of the inhibitors molecules on the

    surface of carbon steel.

    Table 4: Thermodynamic parameters for the adsorption of inhibitors I and II in CO2-saturated brine on the

    carbon steel surface at 323 K

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    Inhibitive Effect of Some Natural Naphthenates as Corrosion Inhibitors on the Corrosive Performance of Carbon Steel

    in CO2-Saturated Brine

    177

    Prof. Dr. Vagif Maharram Abbasov, Doctor of chemical sciences (DSC), Azerbaijan National Academy

    of Sciences, Institute of Petrochemical Processes, Director of Institute of Petrochemical Processes. He

    is a Member of the Editorial Board of "Processes of Petrochemistry and oil refining journal" (Chief

    Secretary). He is a Member of the American Chemical Society. He is an author on 250 papers in

    international journals and more than 35 books. V. M. Abbasov has carried out the thorough researches

    in the field of synthesis of antistatic additives to hydrocarbon liquids including to jet fuels. He for the

    first time proposed the possibility for producing the displaced complexes of nitroalkanes and organic

    acids with the transition metals, developed on their basis the high efficient and polyfunctional antistatic

    additive. This additive was tested and commercialized in perm plant of aircraft engines. V. M. Abbasov

    with coworkers has created in 1997 the polyfunctional waxy deposit corrosion inhibitor "Parkorin-1",

    the commercial tests have been carried out in the Azerbaijan oil fields, jointly exploited by Turkish- Azerbaijan and by

    TSNIIKP (Moscow city) has been recommended for application.

    Dr. Hany M. Abd El-Lateef was born in Sohag, Egypt, in 1982. He received the master degree in

    physical chemistry from the University of Sohag, Sohag, Egypt, in 2009, since that has worked in

    different projects in the field of corrosion science. In 2010, he joined the department of chemical

    resistance of materials and corrosion protection, institute of petrochemical processes, Azerbaijan

    National Academy of Sciences, as a PhD student. He is one of the Editorial board of Chemistry Journal.

    He is an author on 30 papers in international journals and two books. Hany is one of NACE

    membership.

    Dr. Sevinc A. Mamedxanov, Doctor of chemical sciences, Azerbaijan State Oil Academy. She is an

    author on 50 papers in international journals. She obtained degree in Master of Science in

    Petrochemistry from Azerbaijan State Oil Academy. She received his first degree in applied chemistry

    from Azerbaijan State Oil Academy. Her research is focused on the Synthesis of various surfactants,

    compounds soluble in oils and fuels, and their investigation as corrosion inhibitors, additives to fuels,

    oils, polymeric stabilizers, development of theoretical bases for selecting corrosion inhibitors and

    additives.

    Prof. Dr. Leylufer Imran Aliyeva Doctor of Technical Sciences, Azerbaijan National Academy of

    Sciences, Institute of Petrochemical Processes, Head of department. She is a Member of the Editorial

    Board of "Processes of Petrochemistry and oil refining journal". She is an author on 180 papers in

    international journals and more than 18 books. Her work focused on the synthesis of nitroalkanes

    metallocomplexes, high-molecular amines and creation of polyfunctional antistatic additives, corrosion

    inhibitors, inhibitor-bactericides and study of their action mechanism. She has created the high efficient

    polyfunctional sulfurated hydrogen corrosion inhibitors based on -olifins with working capacity in the

    media with H2S, CO2 content more than 25% vol.

    http://www.google.com.eg/url?sa=t&rct=j&q=azerbaijan+neft+academy&source=web&cd=1&cad=rja&ved=0CDEQFjAA&url=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FAzerbaijan_State_Oil_Academy&ei=b1mFUb68HK6w4QTDl4CoDg&usg=AFQjCNGRjlbJ79143AtSz1mBwpRSBndHUA&bvm=bv.45960087,d.Yms

  • International Journal of Scientific Research in Environmental Sciences (IJSRES), 1(8), pp. 166-178, 2013

    178

    Dr. Teyyub A. Ismayilov, Doctor of chemical sciences, Azerbaijan National Academy of Sciences,

    Institute of Petrochemical Processes. He is an author on 50 papers in international journals. T. A.

    Ismayilov has carried out the thorough and extensive researches in the field of creation of the corrosion

    inhibitors and obtained the following important results: on the basis of carbamide and amines there has

    beer created a new method for synthesis of phosphate complexes and organized on their basis the

    production and application of polyfunctional corrosion inhibitors.

    Musayev Javidan Ilham is a Ph.D student in the sphere of quality control at the State Economic

    University of Azerbaijan. He received his first degree from The State Economic University in 2009

    awarded with Bachelor of Science. He obtained Master degree of Science from The State Economic

    University in 2012. His current research is focuses on synthesis and the review in quality of sulfonation

    of acids and saline acids on plant origin.

    Orkhan A. Aydamirov obtained his first degree from the Baku State University in chemistry in 2011.

    He is junior researcher in Petrochemical Institute of Azerbaijan National Academy of Sciences. His

    current research is focuses on corrosion inhibitors and conservation fluids. To date, he has published

    several scientific articles related to corrosion inhibitors. He also interests in alternative energy sources

    and biomass.

    Dr. Fariz A. Amirov is an Assistant Professor in Azerbaijan State Oil Academy. He has more than 22

    years research experience in the field of Petrochemistry. He has published over 70 refereed articles in

    professional journals/proceedings. Dr. F. A. Amirov research has focused on alleviating problems

    associated with oil industry issues from corrosion. He is editor and reviewer of some international

    journals.

  • International Journal of Scientific Research in Environmental Sciences (IJSRES), 1(8), pp. 179-187, 2013 Available online at http://www.ijsrpub.com/ijsres

    ISSN: 2322-4983; 2013 IJSRPUB

    http://dx.doi.org/10.12983/ijsres-2013-p179-187

    179

    Review Paper

    Livestock Products and Environment

    Maryam Asghari

    Researcher in Environmental Economics and International Trade and Assistant Professor at Shahid Ashrafi Esfahani

    University, Esfahan, Iran; Email: [email protected]

    Received 14 May 2013; Accepted 07 June 2013

    Abstract. Increasing demand for livestock products, together with changes in international trade, is placing pressure on the

    livestock sector both to adapt and expand. There is an increasing tendency to greater selectivity as to parts of the animal used

    for food and therefore, there is a trend from multi-purpose to single-purpose animals, with the production of animal protein the

    overriding objective. The aim of this paper is the examination of livestock products effects on environmental quality as

    agricultural trade liberalization happens in the six countries of Gulf Persian region, over 1980-2012. Our results show that this

    is an N-shaped EKC between income and the agricultural land expansion in this region. We find that livestock production

    decreases the percentage annual growth of agricultural land area use in this region as trade in agriculture sector is libered and

    the form of EKC has not changed when we enter livestock production index of the different countries, as agriculture trade is

    libered, in our model.

    Key words: Agriculture Trade Liberalization, Livestock Products, Environmental Quality, Environmental Kuznets Curve,

    Gulf Persian Region

    1. INTRODUCTION

    The livestock has been well knit with the socio-

    economic fabric of our rural economy and played an

    important role in the employment and income

    generation. The developed countries of the world have

    already well recognized the importance of livestock

    for employment and income generation and have

    devolved around their agriculture a prosperous,

    progressive and forward looking livestock enterprise.

    The major components through which livestock

    contribute to the agricultural income are milk and

    milk products, meat and eggs.

    Livestock production is an important resource

    ensuring global food supply, meeting the increasing

    demand for protein and supporting human livelihood

    and well-being. Both extensive and intensive livestock

    production systems require attention and intervention

    to promote fewer negative and more positive impacts

    on social, economic, and environmental aspect, all

    within a global context.

    In the developing countries, the income elasticity

    of demand for livestock products is high as compared

    to cereals. It is also high as compared to the developed

    economies. This implies that with rising per capita

    income, the demand for these products would rise

    faster in the Third World countries.

    Livestock production can contribute to poverty

    reduction and economic growth in those poor

    countries that are not fully exposed to globalized food

    markets. In rapidly growing and developed

    economies, market barriers and economies of scale

    will continue to push smallholders out of production,

    thus alternative livelihoods need to be sought in other

    sectors.

    Standard economic theory concludes that

    liberalised agricultural trade increases social welfare.

    By specialising in the production of food and fibre

    products for which it has comparative advantage, each

    countrys allocative market efficiency can be

    improved, thus permitting higher national and global

    economic growth. The returns from that higher level

    of growth enhance individual incomes, which in turn

    raise national welfare.

    Further liberalization of agricultural trade can

    affect environmental quality and the pattern of natural

    resource use through several, possibly offsetting, and

    effects. Further agricultural trade liberalization can

    affect the scale of production, the composition of

    goods produced in an economy, and the technologies

    used to produce output.

    The rapid increase of intensive (confined) livestock

    production and the land and livelihood needs of

    extensive production (rangeland grazing) are crucial

    challenges. The livestock sector emerges as a very

    significant contributor to environmental problems at

    every scale from local to global, including land

    degradation, climate change and air pollution, water

    shortage and pollution and loss of biodiversity.

    By improving allocative market efficiency through

    liberalised trade, the country enjoys higher economic

    growth and incomes, but the growth also generates

    negative pollution effects from the increased scale of

    economic activity. Increased incomes raise the social

    mailto:[email protected]

  • Asghari

    Livestock Products and Environment

    180

    demand for environmental quality which translates

    into policies that shift product composition and

    techniques of production to meet public

    environmental objectives via less pollution and more

    positive environmental services.1

    By expanding the scale of livestock production,

    trade liberalization can increase pollution. However,

    countervailing forces will tend to offset the scale

    effect by encouraging an economy to use cleaner

    technologies to produce output and by encouraging

    specialization in the production of less pollution-

    intensive goods.

    Total emissions of greenhouse gases (GHGs) from

    agriculture, including livestock, depend on the source

    (US EPA, 2006; IPCC, 2007) and on the proportion of

    land conversion that is ascribed to livestock activities.

    Land-use change is complex and driven by a range of

    drivers, although it is possible to see some strong

    historical associations between land abundance,

    application of science and technology, and land-use

    change in some regions (Rosegrant et al., 2009)

    The implications of livestock demand increases on

    land use in the future are perhaps best discussed in

    relation to the different livestock production systems

    that occur globally. Confined livestock production

    systems in industrialized countries are the source of

    much of the worlds poultry and pig meat production,

    and such systems are being established in developing

    countries to meet increasing demand. Future trends for

    these essentially landless production systems are

    outlined in Steinfeld et al. (2006), who describe a two-

    step process: as developing countries industrialize,

    large-scale monogastric production systems spring up

    and tend to be located close to urban centers to

    minimize the problems associated with product

    conservation and transportation. In the second step,

    transport infrastructure and technology develop

    sufficiently so that these intensive livestock systems

    are located further away from the centers of demand

    for the products. This movement can help to reduce

    some of the economic costs of production (via lower

    land and labor costs), improve access to feed

    resources via reduced feed transportation costs, and

    may also reduce (or make it easier to deal with) some

    of the environmental and human and livestock health

    issues associated with intensive, industrialized

    production (Steinfeld et al., 2006). If this two-step

    characterization of this process is broadly correct, then

    in the future these largely landless systems will

    become concentrated outside peri-urban areas,

    particularly in regions with good access to long-

    1 - Note in this simple conception of the process adapted

    from Runge [1995], structural effects are not broken out

    separately but can be interpreted to fall within the product

    and technology categories.

    distance transportation facilities (ports, railways)

    and/or with good access to plentiful feed resources.

    There are likely to be strong regional differences in

    the growth of industrial (confined) livestock

    production systems.

    This paper attempts to quantify the effect of

    livestock production, when trade is libered in

    agriculture sector, on agricultural land use expansion.

    The remainder of the paper is organized as follows.

    Section II presents the relation between growth and

    environment. Section III specifies the empirical model

    and the data and discusses the empirical results, while

    Section VI concludes.

    2. ECONOMIC GROWTH AND

    ENVIRONMENT

    The issue of worldwide environment has received

    more attention than ever, since global warming and

    other environmental problems are becoming more and

    more serious. In particular, an urgent subject for all

    authorities who are responsible for environmental

    policies is to understand and predict how the

    environmental quality will evolve over time.

    At the 67th annual meeting of the American

    Economic Association in 1954, Simon Kuznets

    delivered the presidential address Economic Growth

    and Income Inequality and suggested that, as per

    capita income increases, income inequality also

    increases at first but then, after some turning point,

    starts declining (Kuznets, 1955). This changing

    relationship between per capita income and income

    inequality can be represented by an inverted-U-shaped

    curve, known as the Kuznets curve, for which Kuznets

    was awarded the Novel prize in economics in 1971.

    The Kuznets curve hypothesis posits that initially, at

    lower levels of per capita income, income distribution

    is skewed toward higher income levels so that income

    inequality is high. As income rises, skewness is

    reduced and income inequality becomes lower.

    The environmental Kuznets curve (EKC for short)

    is referred to as the hypothesis that the relationship

    between environmental degradation and per capita

    income exhibits an inverted-U shape. The logic of the

    EKC relationship is rather intuitive. In early stages of

    industrialization, pollution grows rapidly because high

    priority is given to increasing material output, and

    people are more interested in income than

    environment. In the later stage, however, as income

    rises, the willingness to pay for a clean environment

    increases by a greater proportion than income,

    regulatory institutions become more effective for the

    environment, and pollution level starts declining.

    The EKC hypothesis is usually described by three

    effects: (a) the effect of the scale of economic activity,

    (b) the effect of the changes in the structure of

  • International Journal of Scientific Research in Environmental Sciences (IJSRES), 1(8), pp. 179-187, 2013

    181

    economic activity and (c) the effect of income on the

    demand for pollution abatement efforts (Panayotou,

    2000). The first effect is a monotonically increasing

    function of income: the larger the scale of economic

    activity the higher the level of pollution, all else being

    equal. The second effect reflects the changes in the

    composition of the economic activity toward sectors

    of varying pollution intensity: a shift from agriculture

    to industry implies higher pollution while a shift from

    industry to services reverts this trend. The third effect

    is a monotonically decreasing function of income and

    it reflects the growing demand for environmental

    quality with higher income levels (Kukla-Gryz, 2009).

    Theoretical models on the EKC relationship can be

    classified into several categories; e.g., static vs.

    dynamic, macroeconomic vs. microeconomic, long

    term vs. short term, deterministic vs. stochastic. This

    paper adopts the classification based on static and

    dynamic models. The primary reason is that most

    theoretical studies in the literature mainly focus on the

    macroeconomic production and/or the utility of a

    representative agent without uncertainty. While static

    models are classified into production-based models

    and utility-based models, dynamic models are

    classified further to include policy-based models and

    the real options approach (Kijima, al. 2010)

    Note that most of the theoretical papers succeed

    only to illustrate an inverted-U-shape pattern and few

    of them shows an N-shaped pattern. It is therefore

    required to develop sophisticated models that are

    flexible enough to explain the actual environment-

    income relationship and to predict how the

    environmental quality will evolve in future within a

    unified framework. Such theoretical models supported

    by ample empirical studies can be useful for

    environmental policy makers, because the evolution

    of pollution is linked not only with a development

    path or economic growth, but also with policy

    response. See, e.g., Grossman and Krueger (1995),

    Magnani (2001).

    Conventional EKC studies employ functional

    forms where results can be evaluated with respect to

    the presence or absence of a turning point (TP) and

    the significance of the parameters computed (Agras

    and Chapman, 1999). The following equation shows

    that a reduced functional form is applied to find out

    the best possible relationships between environmental

    pollution level and economic growth:

    Yit = i + 1Xit + 2X2it

    + 3X

    3it + 4Zit + it (1)

    where Y is environmental indicators, X is

    income and Z relates to other variables of influence

    on environmental degradation. Here, the subscript i

    is a country, t is time, is constant, is error

    term while k is the coefficient of the k

    explanatory variables (Chow, 2006; Dinda, 2004;

    Ekins, 1997; Shafik, 1994). Eq. (1) provides us with a

    method to test several forms of environment-

    economic development/growth relationships.

    The model (1) provides important information as

    to the form of the relationship between environment

    and economic growth. Namely, if 01 ( 01 ,

    respectively) while 032 , then there is a

    monotonically increasing (decreasing) relationship

    between income x and environment y. If, on the other

    hand, 01 , 02 and 03 , then we observe

    an inverted-U-shaped relationship, the original EKC

    pattern. Note that, in this case, the turning point of the

    curve is given by2

    1*

    2

    x . Finally, if 01 ,

    02 and 03 , then we come up with an N-

    shaped relationship. Of course,

    when 0321 , this indicates that there is no

    relationship between income x and environment y.

    The other cases are not of interesting the EKC

    literature.

    However, some papers are skeptical about the EKC

    hypothesis, and some criticize the concept and

    methodology of empirical studies. For example, a

    variety of time series, cross-section and panel data

    analyses indicate that the empirical results are

    sensitive to the sample of countries chosen and to the

    time period considered (Grossman and Krueger, 1993;

    Selden and Song, 1994; Hill and Magnani, 2002). The

    results may change by the choice of scaling factors to

    be used in regression models (Borghesi, 2001). Also,

    empirical studies are based on reduced-form models

    that assume specific functional forms a priori to

    estimate the environment-income relationship.1 In

    reality, the environment-income relationship could be

    more complicated than the assumed functional forms

    (see, e.g., Section 4 in Borghesi, 2001). Hence, it is

    not sufficient to conclude an EKC relationship based

    on such empirical studies and, as Pearson (1994)

    argues, more sophisticated techniques of curve fitting

    should be investigated, so that our findings are not

    determined by specific functional forms. The fitted

    function should be decided, based on theoretical

    research, for the complex bi-directional relationship

    between environmental quality and economic-social

    development. A comprehensive review of the

    empirical literature examining the EKC hypothesis is

    presented by Soumyananda (2004) and Verbeke and

    Clercq (2006).

  • Asghari

    Livestock Products and Environment

    182

    Using new international data, Hettige et al. (2000)

    test the environmental Kuznets curve (EKC)

    hypothesis for industrial water pollution. They

    measure the effect of income growth on three

    determinants of pollution: the share of industry in

    national output, the share of polluting sectors in

    industrial output, and end-of-pipe (EOP) pollution

    intensities (per unit of output) in the polluting sectors.

    They find that the industry share of national output

    follows a Kuznets-type trajectory, but the other two

    determinants do not. When combined, their results

    imply rejection of the EKC hypothesis for industrial

    water pollution: it rises rapidly through middle-

    income status and remains roughly constant thereafter.

    Mills et al. (2009) test this environmental Kuznets

    curve (EKC) using estimates of per capita income and

    deforestation rates (index of biodiversity threat) for 35

    tropical countries. They introduce the use of quantile

    regression and spatial filtering to reanalyze this data,

    addressing issues of heteroskedasticity and spatial

    autocorrelation. They note that preliminary analysis

    using these methods provides some initial evidence

    for an EKC. However, a series of panel analyses with

    country-specific dummy variables eliminated or even

    reversed much of this support. A closer examination

    of conservation practices and environmental

    indicators within the countries, particularly those

    countries that drove our initial support, suggests that

    wealth is not a reliable indicator of improved

    conservation practice. Their findings indicate that an

    EKC for biodiversity is overly simplistic and further

    exploration is required to fully understand the

    mechanisms by which income affects biodiversity.

    3. EMPIRICAL MODEL

    1.3. Our Model

    In the above discussions, we have seen that livestock

    products are a key determinant of agricultural land-

    use expansion. So, we need to a new model to the

    cross-country analysis of agricultural land use

    expansion. The model should concentrate on

    explaining agricultural land use expansion, 1 itit AA ,

    on the other hand, agricultural land-use increasing

    have a nonlinear quadratic relationship according to

    the EKC hypothesis. Hence, the long-run steady-state

    relationship between land-use increasing, livestock

    prod