The Adsorption-Degradation Effect Of Peanut Shells Loaded With Sulphonamide-Degrading Bacteria

Sulfonamide antibiotics are potentially harmful to the ecological environment and human health, and control of pollution with these compounds has received much attention. In this study, removal of the four sulfonamides sulfamethoxazole, sulfamethazine, sulfamethazine, and sulfamethoxamine from the water was investigated using a composite material prepared from peanut shells and sulfonamide-degrading bacteria. Adsorption-degradation of the sulfonamides with the composite material was investigated using orthogonal static experiments and dynamic experiments. Scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectrometry, and other microscopic detections and analytical techniques were used to explore the mechanism of action. When the sulfonamide concentration was 0.5 mg/L, the removal rates (%) of sulfamethoxazole, sulfamethazine, sulfamethazine, and sulfamethoxamine by the peanut shell composite were 89.69%, 78.39%, 71.38%, and 88.55%, respectively. The optimum conditions for preparation of the composite material were 50 mL of basic medium, a peanut shell:bacteria ratio of 1.5 g/2.5 mL, and a fixation time of 36 h. The dynamic experiments showed that the composite material performed well for removal of sulfonamides present at the low (0.05 mg/L) and high (5.0 mg/L) concentrations, with average removal rates of 79.89% and 61.53%, respectively. The removal of sulfonamides in water by the composite material occurred mainly by physical and chemical adsorption and biodegradation. Physical and chemical adsorption occurred through the porous structure and active functional groups (C-O, -OH, N=C-O, CH, C=O, -CH3 , and -CH2-) of the peanut shell composite. Biodegradation mainly involved metabolism by sulfonamide-degrading bacteria immobilized on the peanut shells.