Surface modification of alginate sponge using tannic acid and dodecanethiol for diesel oil spill separation from water.

An environmentally friendly absorbent sponge was successfully developed for diesel spill remediation via alginate polymer crosslinking followed by surface modification using tannic acid and dodecanethiol (TA/Do). The optimal sponge was obtained with a 3 h crosslinking duration, achieving a balance between absorption performance and structural durability, while longer crosslinking times led to increased density and reduced efficiency. Surface modification imparted hydrophobicity to the alginate sponge, confirmed by a water contact angle of 120.2°, and the successful incorporation of TA/Do was confirmed from FTIR and XPS analysis. The modified sponge (AA-3-TA/Do) exhibited a diesel absorption capacity of 17.54 g/g-a 36 % increase over the unmodified form-and retained ∼90 % of this capacity after 34 absorption-desorption cycles. Kinetic modeling showed that diesel was rapidly absorbed during early contact, with faster uptake than water. A cytotoxicity assay confirmed its non-toxic nature, indicating environmental compatibility. This study demonstrates that a simple, scalable modification using accessible materials can significantly enhance oil sorbent performance without requiring complex techniques or hazardous reagents.