Adsorptive Removal of Oils from Oil Spillage: Kinetic and Isotherm Studies Using Raw and Chemically Modified Pentaclethra macrophylla Seed Pods

Oil spill remediation using agricultural wastes has become an attractive technique due to its simplicity, low cost and effectiveness. In this work, Pentaclethra macrophylla seed pods, which are readily available agricultural wastes were modified in order to increase their hydrophobicity. The effect of the modification was studied using FTIR analysis. Batch oil sorption tests were conducted using both the raw and modified pods. Results from the FTIR analysis of the raw pods showed peaks corresponding to O-H, C-H, C=O, C=C, and C-O stretching vibrations. The spectra of the modified PMSP showed increased intensity of the peaks owing to the acetylation effect. The spectra of the oil-treated pods show the appearance of intense and sharp peaks corresponding to CH3, CH2 and C-H bending of crude oil. Isotherm studies revealed conformation to the Freundlich model (R² > 0.85), suggesting multilayer adsorption on heterogeneous surfaces, and Langmuir model (R² > 0.99) for modified pods, confirming monolayer coverage on uniform active sites. Pseudo-first order kinetic model best described the oil sorption on the raw seed pods, suggesting physisorption mechanism, with equilibrium oil sorption capacity of 6281 mg/g. For the modified pods, pseudo-second order model best suited the sorption, suggesting chemisorption mechanism, with equilibrium oil sorption capacity of 14286 mg/g. The higher oil sorption capacity of the modified pods indicates their higher potential for application as an environmentally friendly alternative for oil spill remediation and treatment of industrial effluents before disposal.