Utilization of water hyacinth (Eichhornia crassipes) biomass as eco-friendly sorbent for petroleum oil spill cleanup

This study focuses on the removal of spent engine oil (SEO) spill from the water surface using water hyacinth biomass (WHB)-based sorbents. The raw WHB was modified using extra virgin coconut oil (mainly consisting of lauric acid) to enhance the hydrophobicity and floating ability. With varying amounts of coconut oil and solvent, six diverse types of modified water hyacinth biomass (MWHB) were prepared. Among these MWHBs, an equal proportion of coconut oil and raw WHB with 10% methanol solution exhibited the highest removal of SEO reaching 96%. Various sorption kinetics and isotherm models were examined to understand the SEO sorption process on MWHB. The pseudo-second-order kinetics (R2 0.999) and both the Langmuir and Freundlich isotherm models (R2 0.992 and R2 0.999, respectively) were found to be the best-fitting models. These findings indicated a chemisorption mechanism involving the initial monolayer coverage of SEO molecules on the MWHB surface followed by the development of multilayers. The MWHB achieved a maximum sorption capacity of 4.75 g/g within 60 min. Furthermore, the reusability tests showed that MWHB maintained a sorption capacity of over 90% even after the third sorption–desorption cycle.