Oil Palm Shell-Derived Activated Carbon: Adsorption Kinetics, Thermodynamics, and Interaction Mechanism for Lufenuron 50-EC Pesticide

TL;DR

Researchers made activated carbon from oil palm shells and found it can effectively remove a pesticide called lufenuron, with the best sample removing 96.9% of it.

Contribution

The study introduces a new method to produce activated carbon from oil palm shells and evaluates its effectiveness in pesticide adsorption.

Findings

AC-900-2 achieved the highest lufenuron removal yield of 96.9%.

The adsorption process was best described by the pseudo-second-order kinetic model.

Chemically activated carbons showed improved adsorption due to functional groups introduced by KOH.

Abstract

Activated carbon (AC) was synthesized from oil palm shell
(OPS)
through physical (AC-800-2 and AC-900-2) and chemical (AC-750-1.5-3:1
and AC-800-1-2:1) activation processes in a carbon dioxide atmosphere.
KOH was used as an activating agent in the impregnation process in
the case of chemical activation. The synthesized ACs were characterized
by proximate and ultimate analysis, Fourier transform infrared (FTIR)
spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, scanning
electron microscopy (SEM), and textural properties of the samples.
The tested properties, including surface area (S
BET), pore volume (VT), and average pore size (SP), were determined by the Brunauer-Emmet-Teller (BET) method
and the Barrett-Joyner-Halenda (BJH) model. Lufenuron adsorption results
demonstrated that AC-900-2 achieved the highest lufenuron removal
yield of 96.9%. The samples were best represented overall by the pseudo-second-order
kinetic model, with R
2 values between
0.91 and 0.99. This suggests that the lufenuron adsorption process
onto the activated carbons produced in this study was related to the
chemisorption process. In addition, this adsorption process was spontaneous,
exothermic, and exhibited a high probability of reversibility for
samples AC-900-2, AC-750-1.5-3:1, and AC-800-1-2:1, with van der Waals
forces and hydrogen bonds playing a significant role in the interaction
between lufenuron and AC. In contrast, for sample AC-800-2, the adsorption
process required an increase in temperature to become spontaneous,
and the process was endothermic and irreversible. In general, the
high percentages of adsorption observed in the AC produced by physical
and chemical activation could be explained by the strong interactions
of the surface functional groups with lufenuron. In the case of physically
activated carbon, the high surface area provides more sites available
for these interactions. In the case of chemically activated carbon
, although the surface area is lower, the functional groups introduced
using KOH improve the adsorption capacity.

Figures