New Insights into Co-Adsorption of Cr6+ and Chlortetracycline by a New Fruit Peel Based Biochar Composite from Water: Behavior and Mechanism

Nowadays, the residual heavy metals and antibiotics in water and soil have a potential threat to human being health, thereby their purification is of great importance. In this study, the application of Cr6+ and chlortetracycline (CTC) removal using a new fruit peel based biochar composite (FPBC) had been explored. Batch experiments results showed that FPBC presented excellent removal performance on Cr6+ and CTC, and the simultaneous removal efficiencies of Cr6+ and CTC were 97% and 81% within 180 min, respectively. The adsorption kinetics and isotherms of Cr6+ by FPBC could be well described by the pseudo-second-order and Langmuir models, respectively, and its adsorption was a spontaneous endothermic process. The inhibitory of the coexisting anions on Cr6+ removal of followed the order of HPO43-> HCO3-> SO42->NO3-> Cl-. The simultaneous removal of Cr6+ and CTC by FPBC had been achieved at low CTC content levels. The presence of NaCl showed a significant inhibitory on Cr6+ removal but a positive effect on CTC removal at low content level. A potential reaction mechanism of both Cr6+ and CTC removal over FPBC was proposed on the basic of the comprehensive characterizations and adsorption performance. Both reduction and surface precipitation reactions might be dominant in Cr6+ removal process, whereas both complexation and hydrogen bond interaction might be mainly responsible for CTC removal. These findings suggested that this fruit peel based biochar composite might be a promising material for the remediation of Cr6+ and CTC-contaminated wastewater.