Acetylation of Rice Straw with or without Catalysts and Its Characterization as a Natural Sorbent in Oil Spill Cleanup

Abstract

An investigation of the acetylation of rice straw with acetic anhydride at 100 and 120 °C for 1−4 h with four tertiary amine catalysts (pyridine, 4-dimethylaminopyridine, N-methylpyrrolidine, and N-methylpyrrolidinone) or without catalyst in a solvent-free system was undertaken, and the extent of acetylation was measured by weight percent gain, which increased with the extent of reaction time and temperature and the amounts of catalyst used. 4-Dimethylaminopyridine was found to be the most effective catalyst of those studied. At a concentration of 7% of the catalyst in acetic anhydride, a weight percent gain of 15.4% was realized, compared with 11.2% for the noncatalyst reaction, after 0.5 h of exposure to the system at 120 °C. Characterization of acetylated straw was performed by FT-IR, CP MAS ¹³C NMR, and thermal studies. Interestingly, the acetylated straw is significantly hydrophobic and does not get wet with water, thereby offering potential for the better utilization of cheap waste materials as natural sorbents in oil cleanup. Keywords: Rice straw; acetylation; 4-dimethylaminopyridine; FT-IR; CP MAS ¹³C NMR; oil sorbent