Preparation of Ti-modified biochar and its adsorption for Pb(Ⅱ) and Co(Ⅱ)

Tetra-n-butyl titanate was used to modify black peanut shells(PSs) to prepare Ti-based modified PSs biochar(Ti@PB). Its adsorption characteristics for Pb(Ⅱ) and Co(Ⅱ) in mixed solution were investigated. The characterization results of Ti@PB showed that Ti mass fraction reached 33.822%, indicating that Ti was successfully loaded on the surface of the biochar. In addition, the surface of Ti@PB was rough, with many irregular pore structures, which was an adsorbent material with mixture of micropores and mesopores, and the surface functional groups were mainly dominated by oxygen-containing functional groups. The removal of Pb(Ⅱ) and Co(Ⅱ) by Ti@PB was enhanced compared to the biochar prepared from unmodified PSs. The kinetic study demonstrated that the removal of Pb(Ⅱ) by Ti@PB followed the quasi-second-order kinetic equation and was dominated by chemisorption, while the removal of Co(Ⅱ) was more consistent with the quasi-first-order kinetic equation and was predominantly physisorbed. The isothermal adsorption fitting results showed that the adsorption of both Pb(Ⅱ) and Co(Ⅱ) by Ti@PB conformed to the Freundlich model as multilayer non-homogeneous phase adsorption.