Abstract
Petroleum-related activities ranging from exploration and refining to transport and storage frequently lead to environmental challenges, particularly marine oil spills. In this study, coir pith (CP), an abundant lignocellulosic waste, was functionalised via microwave-assisted graft copolymerisation using sodium alginate-grafted polyacrylamide (SAG-g-PAM) to produce a composite sorbent (CP/SAG-g-PAM) for oil spill remediation in simulated salt water. The composition of CP (3–10%) was varied in the biocomposite. The grafted copolymer was characterised using FTIR, 1H NMR, SEM, BET and zeta potential (ZP) analysis to explore surface charge behaviour. A diesel and petrol oil-in-water emulsion was used to investigate sorption dynamics under varying parameters including contact time, sorbent dosage, initial oil concentration and agitation speed. Complementary tests were conducted to evaluate the solubility, oil uptake and water sorption properties of the native and modified materials. The 10%CP/SAG-g-PAM composite exhibited significantly enhanced sorption performance, achieving a peak capacity of 4.2 ± 0.11 g/g for petrol and 4.9 ± 0.12 g/g for diesel at 80 ± 2 min. These values significantly exceed those of the bare SAG-g-PAM, which recorded only 2.9 ± 0.08 g/g (petrol) and 3.4 ±0.10 g/g (diesel) under the same conditions, repress enting a ∼33% and ∼45% enhancement, respectively. Increasing the initial oil dosage to 5 g yielded maximum capacities of 4.1 ± 0.14 g/g (petrol) and 3.9 ± 0.10 g/g (diesel) at an agitation speed of 40 rpm. Interestingly, diesel sorption declined with higher sorbent doses, whereas petrol uptake increased, reaching 4.8 ± 0.14 g/g at 0.1 g dosage. This finding highlights 10%CP/SAG-g-PAM as a promising, eco-friendly sorbent with strong potential for future application in oil spill cleanup and wastewater treatment systems.