Influence of Activated Carbon on Fate of Sulfamethoxazole and Acetaminophen in Soil

The present paper is the subsequent one of the series concerning the effect of organic amendments on fate of sulfamethoxazole and acetaminophen in soil. In the present study, the influence of activated carbon (AC) on mineralization, degradation, extractable residues and bound residue formation of 14C-sulfamethoxazole and 14C-acetaminophen was investigated. The results showed that AC facilitated the dissipation of 14C-sulfamethoxazole and 14C-acetaminophen and their formation of bound residue, and exerted a significant inhibitory effect on their mineralization. The addition of 0.05-2% AC showed an extraordinarily strong adsorption capacity of acetaminophen with Kd values of 47.2-409.8 times higher than that in the non-amended soil, as compared to 21.0-2273.4 times for sulfamethoxazole. An inverse relationship was found between sorption strength and mineralization or degradation kinetics. The effect of AC was likely due to its higher OC content and the enhancement of surface areas and pore volumes where additional sites might be provided for binding or conjugation interactions with sulfamethoxazole or acetaminophen or their transformation products. Results from the present study clearly highlighted the significance of AC for influencing the fate of sulfamethoxazole and acetaminophen and stressed that sorption was potentially a critical factor in controlling the fate processes in soil.