Potential removals of tetracycline and sulfamethoxazole by iron-loaded sludge biochar

In this study, the potential of iron-loaded sludge biochar (ISBC) to remove tetracycline (TC) and sulfamethox-azole (SMX) was investigated. Under the optimized conditions (initial pH of 4 and 5, ISBC dose of 1.0 g/L, contact time of 720 min, and temperature of 298 K), the maximum removal capacity of ISBC for TC and SMX was 81.04 mg/g and 80.19 mg/g, respectively. The better simulations of TC and SMX removal by Langmuir model and pseudo-second-order kinetic model indicated that monolayer chemisorption dominated their removal. Their removal rates depended on liquid film diffusion, intraparticle diffusion and chemical reactions. Moreover, their removal was a spontaneous and endothermic process with increasing randomness between the solid-liquid in-terfaces. Besides, their removal likely included two simultaneous pathways: adsorption/surface degradation and degradation/adsorption/surface degradation. Furthermore, ISBCs could be effectively desorbed and regenerated by ultrapure water and NaOH. In summary, ISBCs had the potential to be practically applicable for TC and SMX removal.

Automated summary

The study investigated the potential of iron-loaded sludge biochar (ISBC) to remove tetracycline (TC) and sulfamethoxazole (SMX). Under optimized conditions, the maximum removal capacity of ISBC for TC and SMX was determined. The results indicated that monolayer chemisorption dominated the removal process and different factors influenced the removal rates.