Preparation of chitosan-iron oxide modified sludge-based biochar for effective removal of tetracycline from water: performance and mechanism

Abstract

The release of antibiotics has attracted wide attention due to their abuse and discharge. How to remove these emerging contaminants is an urgent need to be solved.In the present study, sludge-based biochar combining chitosan and iron oxide was prepared via municipal sewage sludge. The novel biochar modified with chitosan and iron oxide exhibited satisfying performance in eliminating antibiotics from water. The application of modified biochar combined with activated persulfate (PS) showed a remarkable removal efficiency of 96.98% for tetracycline (TC). Analysis of the surface characteristics of the modified biochar showed the presence of structural defects, dispersed iron oxides, numerous functional groups, a porous structure, and a relatively stable crystal structure. These characteristics contributed significant importance to facilitating the removal/degradation of TC. The investigation indicated that the removal efficiency was maintained at feasible conditions with the treatment process under a low TC concentration (30 mg/L), with a temperature at T=308.15K, solution pH=4. Three degradation pathways and seven intermediate products of TC were proposed. Therefore, our study provides a promising approach for developing effective removal of antibiotics pollutants.