Simultaneous adsorption of phosphate and tetracycline by calcium modified corn stover biochar: Performance and mechanism

It is important to solve the problems of biomass treatment and combined contaminants removal in environmental remediation. In this study, a calcium (Ca) modified biochar (CaBC800) was fabricated using corn stover (CS) as a raw material to remove phosphate and tetracycline (TC). The experimental results indicate that CaBC800 can adsorb both inorganic phosphate and organic TC. The entire adsorption process corresponds to pseudo-second-order kinetics and Langmuir adsorption isotherm. The maximum adsorption capacities of phosphate and TC were 33.944 and 33.534 mg/g, respectively. The phosphate adsorption was demonstrated to mainly depend on the chemical precipitation by Ca2+ and ligand exchange by hydroxyl groups from CaBC800. Meanwhile, hydrogen bonding from oxygen functional groups and pi-pi interactions from aromatic rings are the main adsorption mechanisms of TC. This study provides a new adsorbent to efficiently remove phosphate and TC, and the simultaneous adsorption indicates the application potential of CaBC800 in wastewater remediation.

Automated summary

In this study, a calcium modified biochar (CaBC800) was successfully fabricated to simultaneously remove phosphate and tetracycline from wastewater. The experimental results showed that CaBC800 had high adsorption capacities for both pollutants and the adsorption process followed pseudo-second-order kinetics and Langmuir adsorption isotherm. Chemical precipitation and ligand exchange were the main mechanisms for phosphate adsorption, while hydrogen bonding and pi-pi interactions were the main mechanisms for tetracycline adsorption.