DOI: https://doi.org/10.55373/mjchem.v25i3.425

Keywords: Polypyrrole, MSPE; oil palm activated carbon; graphene; endosulfan

Abstract

Two different carbon sorbents, graphene oxide (GO) and oil palm-based activated carbon (AC) were enhanced with magnetic polypyrrole (Mag-PPy) respectively to produce GO-Mag-PPy and AC-Mag-PPy. The synthesized sorbents were tested and compared based on the adsorption behaviour for micro-dispersive separation of endosulfan (ESO) in environmental waters using a gas chromatography microelectron captured detector (GC-μECD). Based on the extraction, the limit of detection (LOD) in decreasing order is GO-Mag-PPy > AC-Mag-PPy > Mag-PPy. This is expected, as the surface areas of the sorbents were dependent on the base sorbent used in the field emission scanning electron microscope (FESEM). When comparing GO-Mag-PPy and AC-Mag-PPy adsorption rates to their precursors, Mag-PPy, the sorbents with PPy addition were able to adsorb ESO more rapidly compared to its precursors. The rate of GO-Mag-PPy (0.50 mg g-1min-1) was 30% higher than AC-Mag-PPy (0.23 mg g-1min-1), followed by Mag-PPy (0.19 mg g-1min-1). From FESEM result, there is a difference in PPy coating on top of AC and GO, whereby GO was fully covered by PPy, while AC cavities were not thoroughly covered by PPy. This suggests different types of adsorptions occurring on the sorbent respectively. Adsorption capacities, represented by qm at Ce= 50 μg L-1, in decreasing order were AC-Mag-PPy > GO-Mag-PPy > Mag-PPy. It is obvious that the addition of PPy only enhanced the adsorption capacity of sorbent to a certain extent. GO-Mag-PPy sorbent has the lowest LOD for the extraction of endosulfan. A reusability study found that AC-Mag-PPy is more robust compared to GO-Mag-PPy and Mag-PPy due to the physical shielding of magnetite and PPy in its cavities. It was concluded that the molecular structure of the base sorbent influenced the manner of the PPy and magnetite binding, and hence differ in the adsorption trends of ESO.