One-Step-Modified Biochar by Natural Anatase for Eco-Friendly Cr (VI) Removal

The global serious pollution situation urgently needs green, efficient, and sustainable development methods to achieve heavy metal pollution control. The photocatalytic properties of anatase are sufficient to achieve pollution control by providing photoelectrons to harmful heavy metals. However, since natural anatase particles tend to agglomerate and deactivate in water, most studies have been conducted to prepare TiO2–biochar nanocomposites using chemical synthesis methods. In the present study, we utilized pyrolytic sintering to load natural anatase onto biochar to obtain natural anatase–biochar (TBC) composites. Characterization tests, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS), showed that anatase was uniformly partitioned into the surface and pores of biochar without destroying the lattice structure. Due to its photocatalytic properties, TBC degraded Cr (VI) by 99.63% under light conditions. This is 1.58 times higher than the dark condition. Zeta potential showed that the surface of the TBC was positively charged under acidic conditions. The charge attraction between TBC and chromium salt was involved in the efficient degradation of Cr (VI). Different sacrificial agents as well as gas purge experiments demonstrated that photoelectrons (e−) and superoxide radicals (O2−) dominated the degradation of Cr (VI). TBC has the characteristics of high efficiency, stability, and sustainability. This may provide a new idea for the preparation of photocatalytic materials and the realization of environmental protection and sustainable development through heavy metal pollution control.