Enhanced arsenic removal by biochar modified with nickel (Ni) and manganese (Mn) oxyhydroxides

Two biochar composites were synthesized by either pyrolysis of Ni/Mn oxide-modified pinewood feedstock (NMMF) or precipitation of Ni/Mn-LDHs onto pristine biochars (NMMB). Both sorbents were characterized and results indicated that NiO and MnO were dominant crystals in NMMF, whereas Ni/Mn-LDHs in NMMB. Sorption experiment showed that the maximum As(V) sorption capacity were 0.549 and 6.52 g kg−1 for NMMF and NMMB, respectively. The As(V)-loaded sorbents can be easily desorbed with 0.1 NaOH, and NMMB maintained 98% removal efficiency after two to three desorption–resorption cycles. The As(V) sorption is mainly attributed to anion exchange and surface complexation by NMMB and surface complexation by NMMF.

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