Efficient simultaneous removal of cadmium and arsenic in aqueous solution by titanium-modified ultrasonic biochar.

Simultaneous removal of cations and anions in wastewater has always been a great concerned environmental problem. In this study, a friendly and inexpensive biosorbent to simultaneously remove Cd(II) and As(V) from aqueous solution was synthesized by ultrasonic biochar and nanoscale TiO2 (TD), and the obtained sorbent was named as BCTD. The maximum sorption capacities of Cd (72.62 mg/g) and As (118.06 mg/g) were much higher than that of other carbon-materials. Both experiments showed that the Cd(II) and As(V) adsorption capacity was above 70% at pH = 5. The Cd(II) and As(V) adsorption on BCTD had a competitive effect in binary metal solutions at above 100 mg/L. The BET, SEM-EDS, FTIR and XPS analyses proved that ultrasonically reacting enhanced the surface area and pore volume of biochar and TD was supported on the biochar surface and inner pores successfully, and the dominant sorption mechanism by BCTD was the ion exchange and complexation.