Ultrafast sequestration of cadmium and lead from water by manganese oxide supported on a macro-mesoporous biochar

In this study, we first synthesized a biochar with enlarged pore channel (namely K-BC) by adding KHCO3 during the biochar pyrolysis process and then employed the K-BC as a supporter to fabricate a new manganese oxide-based composite (namely HMO-K-BC). It is striking that the effective intra-particle diffusion coefficient D of Pb(II) inside the K-BC is comparable to that in aqueous solution (1.5 × 10−6 v.s. 2.1 × 10−6 cm2 s−1). Although the D value of Pb(II) inside the HMO-K-BC was reduced to 1.8 × 10−7 cm2 s−1, it is still 1–2 orders of magnitude higher than that of conventional adsorbents such as activated carbon, ion exchanger and biochar. As a result, the HMO-K-BC can rapidly sequestrate Pb(II) and Cd(II) within 7.5 min. The HMO-K-BC can also selectively remove Pb(II) and Cd(II) in the presence of high level Ca(II) and humic acid. Column tests further showed that HMO-K-BC was able to effectively treat simulated and real Pb(II)- and Cd(II)-polluted wastewater in a high-flow system with superficial liquid velocity of 0.53 m h−1 (20 BV h−1). All the results manifest that expanding pores of biochar is a promising measure for promoting the practical application of biochar supported composites in wastewater treatment.Graphical abstract
Source: Chemical Engineering Journal - Category: Chemistry Source Type: research
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