Accelerated antimony and copper removal by manganese oxide embedded in biochar with enlarged pore structure

Antimony and copper pollution pose significant threat to water quality security, and their advanced treatment is still a great challenge. In this study, we fabricated a hybrid adsorbent (denoted as MO-L-BC) through dispersing manganese oxide (MO) inside a biochar with enlarged pore structure (namely L-BC). The used carrier L-BC possessed a high proportion of large pores (>2 nm) (87%), and thus lowered the diffusion resistance of target pollutants in pore region of MO-L-BC. Consequently, Sb(III) and Cu(II) adsorption onto MO-L-BC achieved equilibrium within 15 min, and their effective coefficients of intra-particle diffusion (D) were calculated to be 8.6 × 10 −8 and 1.5 × 10 −7 cm 2 s −1 , respectively, which were only one-order magnitude lower than that in aqueous phase. XPS analysis indicated that 53.3% of the sorbed Sb(III) was oxidized to Sb(V) by the impregnated MO. Coexisting substances such as HCO 3 − , SO 4 2− , NO 3 − , Ca 2+ , Mg 2+ and humic acid up to 20 times higher concentration than target contaminants (Sb(III) or Cu(II)) caused only < 20% drop in sorption capacity of MO-L-BC, and the mutual effect of Sb(III) and Cu(II) was also not noticeable. The fixed-bed column adsorption tests showed that MO-L-BC can achieve the tertiary treatment of either the singly polluted (Sb(III) or Cu(II)) or the co-contaminated wastewater at a high flow rate of 0.27 m h −1 , with effective treatment volumes larger than400 BV, and the saturated MO-L-BC can be effectively regenerated. MO-L-BC is a promising engineered biochar to treat Sb(III) and/or Cu(II) contaminated water especially under high-flow conditions.