Abstract: In order to explore the adsorption performance of carbon aerogels modified by NaOH/H₃PO₄ for methylene blue, carbon aerogels was modified by chemical activation method. The effects of pH value of methylene blue solution, initial concentration of solution, gel adsorption time and gel dosage on the adsorption effect of carbon aerogels modified by NaOH/H₃PO₄ were studied through batch experiments. The experimental results showed that the adsorption capacity of modified carbon aerogels for methylene blue decreased with the increase of pH, and the adsorption effect of modified carbon aerogels for methylene blue was the best when pH=8. The adsorption capacity of modified carbon aerogels could be improved by prolonging the gel adsorption time, increasing the initial concentration of solution and increasing the gel input. Under the conditions of dye solution pH=8, initial concentration 50 mg/L, adsorption time 12 h and gel input 5 mg/mL, the adsorption capacity of NaOH modified gel could reach 7.51 mg/g, and that of H₃PO₄ modified gel can reach 4.29 mg/g, both of which were higher than that of unmodified carbon aerogels, it indicates that acid-base modification can improve the adsorption performance of watermelon peel-based carbon aerogels.

Key words: watermelon peel, carbon aerogels, methylene blue, adsorption