Phosphorous-Functionalized Wheat Straw Biochar for the Efficient Removal of Cadmium and Lead in Aqueous Solution

Biochar is an attractive and environmental friendly heavy metal sorbent, but is full-scale application is usually restricted by the limited sorption sites and surface area. Phosphate groups could strongly complex with heavy metal ions. Therefore, in the present study, phytic acid (PA) modified biochar (P-WBC) was prepared via the hydrolysis carbonization of wheat straw and PA at 300 ? and 700 ?. After PA modification, the specific surface areas of P-WBC300 and P-WBC700 were 278.2 m(2) g(-1) and 457.6 m(2) g(-1), respectively, which was 161.5-278.0 times than that of the unmodified wheat straw biochar (WBC). Besides, the micropore structure, P content and ash content of the P-WBC300 or P-WBC700 were also higher than those of WBC300 or WBC700. The higher P content confirmed that P-containing groups were successfully introduced to the surface of WBC. Consequently, the removal of Pb(2+)and Cd2+ was enhanced by the increased phosphorous groups and specific surface area of P-WBC. FTIR and XPS analysis indicated that the adsorption of Pb2+ and Cd2+ in aqueous solution by P-WBC is mainly through complexation with functional groups and electrostatic attraction. This study might provide a feasible way for the development of ideal biochar-derived sorbents for heavy metal remediation.

Automated summary

In this study, modified biochar was prepared by hydrolysis carbonization of wheat straw and phytic acid. The modified biochar exhibited higher surface area, micropore structure, and P content, leading to enhanced removal of Pb(2+) and Cd2+.