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Modified montmorillonite with alkylamine
chloroanthraquinone as a colorimetric sensor for detection
and separation of Cu2+ from an aqueous solution
Journal: Songklanakarin Journal of Science and Technology
Manuscript ID SJST-2019-0273.R2
Manuscript Type: Original Article
Date Submitted by the
Author: 13-Nov-2019
Complete List of Authors: Thongkum, Duangrat; Naresuan University, Chemistry
Nomnuch, Thitiporn; Naresuan University, Chemistry
Chuenchomnakjad, Saksit; Rajamangala University of Technology Lanna,
Program of Industrial Engineering
Keyword: adsorption, chloroanthraquinone, colorimetric sensor, copper ion, montmorillonite
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Songklanakarin Journal of Science and Technology SJST-2019-0273.R2 Thongkum
For Review Only
Original Article
Modified montmorillonite with alkylamine chloroanthraquinone as a colorimetric
sensor for detection and separation of Cu2+ from an aqueous solution
Duangrat Thongkum1*, Thitiporn Nomnuch1, and Saksit Chuenchomnakjad2
1Department of Chemistry, Faculty of Science, Naresuan University,
Mueang, Phitsanulok, 65000 Thailand
2 Program of Industrial Engineering, Rajamangala University of Technology Lanna
Phitsanulok, Mueang, Phitsanulok, 65000 Thailand
* Corresponding author, Email address: [email protected]
Abstract
To compare the adsorption capacity of Cu2+ between Mt and Mt modified with
alkylamine chloroanthraquinone colorimetric sensor (Mt-L), the adsorption properties of
Mt and Mt-L with Cu2+ were studied by using UV-vis spectroscopy. Their structures were
characterized by FTIR spectroscopy and XRD techniques. The adsorbent quantity on the
removal efficiency of Cu2+, effect of pH, effect of initial Cu2+ concentration, equilibrium
adsorption time, adsorption kinetic and adsorption isotherm were determined. The results
revealed that the maximum adsorption efficiency was 54% with an initial Cu2+
concentration of 3.5010-3 M, 40.0 g/L of Mt-L and an initial pH of 5.0. The adsorption
kinetic displayed the pseudo-second order model and the adsorption isotherm
corresponded to the Langmuir isotherm. The qm of Mt-L was calculated to be 9.5511 mg/g
which was higher than the adsorption of Cu2+ on Mt (2.6260 mg/g). Therefore, Mt-L was
a great potential adsorbent for Cu2+ ion adsorption in aqueous solution.
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Keywords: adsorption, chloroanthraquinone, colorimetric sensor, copper ion,
montmorillonite
1. Introduction
Copper is a heavy metal which is considered as one of the most toxic mineral
contaminant in soil and water resources. The effects on human health caused by copper
are liver damage, Wilson disease, Alzheimer’s disease, etc (Borchard et al., 2018;
Roberts, 2011; Squitti et al., 2018). The maximum permissible limit for copper in drinking
water by the World Health Organization (WHO) is 2 mg/L (Datta, Uslu, & Kumar, 2015;
Uddin, 2017). Therefore, it is necessary to cleanup water and metal-contaminated waste
water before its discharge to environment.
There are many techniques for the treatment of water and waste water
contaminating heavy metals, such as, chemical precipitation, solvent extraction,
membrane filtration, ion exchange, electrochemical removal and coagulation (Fan, Zhou,
Jiang, Huang, & Lang, 2014; Rasouli, Aber, Salari, & Khataee, 2014). However,
adsorption is considered as an efficient, simple and low-cost technique (Shirzad-Siboni,
Khataee, Hassani, & Karaca, 2015; Wu et al., 2011). Many studies have reported the
adsorption of metallic ions from water by various adsorbents such as activated carbon,
zeolite and clay mineral (Burakov et al., 2018; Uddin, 2017).
Clay minerals are hydrous aluminosilicates, sometimes with variable amounts of
alkali metals, alkaline earth metals and other cations (Bhattacharyya & Gupta, 2008;
Uddin, 2017). The characteristics of clay minerals are high specific surface area, high
cation exchange capacity (CEC), chemical and mechanical stability, as well as low-cost
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(Gonçalves dos Santos, Grassi, & Abate, 2015). During the past decades, the metal ion
adsorption studies by clay minerals were mainly focused on montmorillonite (Mt).
Abdellaoui et al. (2019) studied the divalent heavy metals adsorption behavior by
commercial montmorillonite and reported the Cu2+ adsorption capacity increases with an
increase in pH of the solution. This behavior can be attributed to the surface charge of the
clays and the competence between the H+ and the divalent ions by the adsorption sites at
lower pH. However, when the pH increases, the clays become negatively charged surface,
and the repulsive force decreases. Therefore the removal of Cu2+ begins to increase. The
adsorption and separation of Cu2+ from an aqueous solution using montmorillonite had
been investigated by Datta et al. (2015). In the kinetic experiments, the maximum
adsorption capacity for the separation of Cu2+ ion from aqueous solution was found
(predicted by the Langmuir model) to be 2.6260 mg/g. However, little has been reported
that investigate modified-Mt with colorimetric sensor to detect Cu2+ in aqueous solution
and also to optimize the adsorption capacity of Cu2+ as well.
The purposes of this present study are to compare the adsorption capacity of Cu2+
ion in aqueous solution between Mt and Mt modified with alkylamine
chloroanthraquinone colorimetric sensor or Mt-L and to evaluate the adsorption
parameters such as adsorbent dosage, pH and Cu2+ ion concentration. In addition, the
color, the adsorption kinetic and the adsorption isotherm studies were determined to
understand the adsorption mechanism of Cu2+ ion on modified-Mt surfaces.
2. Materials and Methods
2.1 Materials
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Montmorillonite-K10 (CEC 120 cmol/kg) and Cu(NO3)2·3H2O were purchased
from Sigma Aldrich. All of the solvents used were of analytical grade and they were
purified by distillation under nitrogen gas before using. The colorimetric sensor L was
synthesized according to the literature (Kaur & Kumar, 2008; Ranyuk et al., 2011) by
using the substitution reaction between 1,8-dichloroanthraquinone (0.40 g, 1.5 mmol) and
2-picolylamine (0.22 mL, 2 mmol) with K2CO3 (0.30 g, 2 mmol) in toluene (40 mL). The
mixture solution was refluxed for 2-3 days under nitrogen atmosphere. Initially the
solution was yellow and upon heating turned to red. Then, the solvent was removed under
reduced pressure. The residue was dissolved in CH2Cl2, and 3M HCl was added to adjust
pH 1. The resulting residue was extracted with CH2Cl2 and water. The organic phase was
dried over anhydrous Na2SO4, filtered and evaporated. The crude residue was purified by
column chromatography (SiO2, CH2Cl2) to yield red solid (45%). The final product was
characterized by FTIR, 1H-NMR and 13C-NMR spectroscopic techniques.
2.2 Characterization techniques
The functional groups of Mt and Mt-L were recorded by attenuated total
reflectance Fourier transform infrared spectroscopy (ATR-FTIR) on a PerkinElmer in the
spectral range 4000-400 cm-1. The X-ray diffraction patterns were performed with a
Panalytical XRD instrument at 2 value range 5-80 degree using Cu K = 0.154 nm.
The absorbance of Cu2+ was measured with a SPECORD 200 PLUS UV-Vis
spectrophotometer over the wavelength range 200-1000 nm.
2.3 Modification of Mt
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The synthesis of L modified Mt (Mt-L) was prepared in 250 mL of volumetric
flask by dispersion 6 g of Mt in 1.5:1 ratio of CH3CN:H2O for 2 h at room temperature
using a magnetic stirrer. Then, the 6.0010-5 M of L in the same ratio of solvent was
added to Mt dispersive solution. The mixture was then adjusted to the pH with 0.1 M
NaOH and 0.1 M HCl while stirring for 2 h. After that, th
