INTRODUCTION

Nelson Giovanny Rincón Silva 1, Juan Carlos Moreno1 , Liliana Giraldo 2

1Universidad de los Andes, 2Universidad Nacional de Colombia.

II Workshop of Adsorption, Catalysis and Porous Materials (IIWACPM)

SYNTESIS OF ACTIVATED CARBON

Activated carbons obtained have textural and physicochemical

properties appropriate for adsorption of phenol

The adsorption process is favored over the sample CEB and can

remove greater amount of phenol.

Thermodynamic studies demonstrate negative free energy and

enthalpy changes

Based on thermodynamic parameters, the adsorption is primarily

physical in nature

REFERENCES[1] M.W. Jung, K.H. Ahn, Y. Lee, K.P. Kim, J.S. Rhee, J.T. Park, K.J. Paeng,

Microchem. (2001). Adsorption characteristics of phenol and chlorophenols on

granular activated carbons.

[2] Q. Liu, T. Zheng, P.Wang, Ji. Jiang, N. Li. Chemical Engineering Journal.

157 (2010). Adsorption isotherm, kinetic and mechanism studies of some

substituted phenols on activated carbon fibers.

Synthesis of Activated Carbon

Characterization of activated Carbon

Application in phenol removal and

Adsoption thermodynamics

METHODOLOGY

Langmuir equation is applicable in all cases, which assumes that

the adsorption occurred in specific localized sites on the carbon surface, and that only

one of the adsorbate molecule is adsorbed onto each site

Phenol and derivatives are

priority pollutant

Basic groups

(meq g-1)

Acid groups

(meq g-1)

pHPCC

0,108 0,1626,67

0,699 0,1168,49

Adsorbent SB.E.T

(m2 g-1)

Vo DR

(cm3 g-1)

CA 650 0,252

CB 825 0,383

Equilibrium studies (Adsoption isotherms)

Characterization

In this study, the ΔG° values are between −0,55 to −5,76 kJ mol-1, indicating that adsorption is mainly physical.

The ΔH° values are negative for all phenols, demonstrating the exothermic nature of these

adsorptions. In this research, the ΔH° values are in the range of –7,22 to −26,09 kJ mol-1, whose absolute values

decrease with the increase of substitution degree, indicating the reinforcement physical adsorption.

CarbonActivating

AgentConcentrations

Carbonization

Temperature (°C)

CA H2SO4 25 % v/v 600

CB NaOH 20 % m/v 750

Adsorption thermodynamic

Adsorbate Sample-ΔG° 20°C

(KJ mol-1)

-ΔG° 30°C

(KJ mol-1)

-ΔG° 40°C

(KJ mol-1)

-ΔH°

(KJ mol-1)

ΔS°

(J mol-1)

PhenolCA 0,68 0,55 0,17 7,22 -22,26

CB 5,76 3,95 4,81 26,09 70,5

In this study, the ΔS° value rises with the

presence of chloro or nitro groups, hence,

it can be deduced that more adsorbed

water molecules are displaced by phenols

with higher substitution degrees.

Phenols adsorption isotherms were studied at 20, 30 and 40 °C, the substituted phenols present greater adsorption, which follow the order of:

4-CP ˃ 4-NP ˃ Phenol

The experimental data were fitting to two models: Langmuir and Freundlich, the sample with higher phenols adsorption capacity is CB, aspect determined according to the monolayer adsorption values Qmax according to the Langmuir model, the 4-CP is the compound that

presents higher adsorption.

4-NP 4-CP