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/MnLDHs in NMMB. Sorption experiment showed that the maximum As(V) sorption capacity were 0.549 and
6.52 g kg1 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