Production of Activated Carbon from Grape Pomace (Vitis labrusca) by Chemical Activation with ZnCl2 and Its Application in Phenol Adsorption

TL;DR

This study shows that activated carbon made from grape pomace can effectively remove phenol from water, making it a sustainable solution.

Contribution

The paper introduces a novel method for producing activated carbon from grape pomace using ZnCl2 activation for phenol adsorption.

Findings

Activated carbon achieved a maximum phenol adsorption capacity of 180 mg g–1.

The pseudo-second-order model best described the adsorption kinetics.

The adsorption process was found to be spontaneous and favorable with negative ΔG° values.

Abstract

This study investigated
the production of activated carbon
from Vitis labrusca grape pomace through
chemical activation
with ZnCl2 and subsequent carbonization at varying temperatures
and times using a fractional factorial design. The best performance
for phenol adsorption was obtained at 800 °C for 120 min, achieving
a maximum adsorption capacity of 54.04 mg g–1. The
activated carbon presented a high specific surface area (1017.58 m2 g–1), meso- and micro-porous structure
(type I and IVa isotherms with H4 hysteresis), oxygenated functional
groups, and thermal stability. Adsorption kinetics were studied at
different phenol concentrations (50–150 mg L–1), and the experimental data were fitted to pseudo-first-order, pseudo-second-order,
and Elovich models. The results revealed that the pseudo-second-order
model better described the kinetic data. Regarding the equilibrium
studies, the maximum adsorption capacity was 180 mg g–1. Isotherm modeling indicated that the Freundlich model was the most
appropriate. Thermodynamic analysis indicated that the adsorption
process is spontaneous and favorable, with ΔG° values of −18.85, −20.03, and −21.53
kJ mol–1 at 25, 45, and 55 °C, respectively,
ΔH° of 6.2 kJ mol–1,
and ΔS° of 83.8 J mol–1 K–1 at 45 °C, demonstrating that higher temperatures
enhance adsorption. Reuse tests showed that after five adsorption–desorption
cycles, the adsorbent maintained its mechanical integrity and physical
stability. These findings confirm that grape-pomace-derived activated
carbon is a sustainable and effective material for phenol removal
from aqueous solutions.

Figures