Comparative Performance of Stearoyl Chloride-Modified Cellulose Sponges from Five Lignocellulosic Wastes for Oil/Water Separation

Increasing industrial activity and oil spills have turned oil pollution into a serious threat to aquatic ecosystems. This study compares five lignocellulosic wastes—rice husk, chestnut shell, tissue dust, cotton lint and chemical pulp—as raw materials for chemically modified cellulose sponges as a sustainable oil-removal solution. Cellulose fibres were converted into three-dimensional porous sponges by freezing and lyophilisation, then rendered hydrophobic and oleophilic by esterification with stearoyl chloride, confirmed by a new ester carbonyl band in the FTIR spectra of all five sample series. After modification, static water contact angles increased from a superhydrophilic 0° to 115–136.5°, and the sponges adsorbed oils and organic solvents at 12–17 times their own dry weight, retaining over 70% of this capacity after ten regeneration cycles. Chemical purity (α-cellulose content and lignin/extractive ratio) was the main determinant of performance: sponges from cotton lint and chemical pulp outperformed those from unprocessed agricultural wastes (rice husk, chestnut shell) in hydrophobicity and sorption capacity, while the latter showed compensating gains in mechanical strength. These findings indicate that lignocellulosic-waste-derived cellulose sponges are an environmentally friendly, high-performance sorbent with strong potential for oil-spill clean-up and oily wastewater treatment, with raw material choice guided by the intended application’s priorities.