38 / 2021-06-29 09:42:47

Simultaneous adsorption of lead and tetracycline from aqueous solution by manganese enriched biochar derived from Phytolacca acinosa Roxb. residues after phytoremediation

Hyperaccumulator disposal; MnOx-loaded biochar; Lead; Tetracycline; Binary adsorption

Biochar technology could provide a value-added solution for hyperaccumulator disposal. The manganese (Mn) enriched hyperaccumulator Phytolacca acinosa Roxb. residues, were expected to convert into MnO_x-loaded biochar with acceptable environmental risk. This study aimed to evaluate the chemical form and variation of Mn in resulting biochar under different pyrolysis temperature (300, 450 and 600 °C) and its contribution to decontamination efficacy of lead (Pb(Ⅱ)) and tetracycline (TC) from aqueous solution. The results illuminated that pyrolysis temperature is a crucial factor of Mn fraction and bioavailability in the resultant biochar and pyrolysis temperature under 450 °C may be most suitable for reutilization without potential risk. The Mn-enriched PSB450 exhibited more preferential sorption toward Pb(II) and TC (279.33 mg/g for Pb(Ⅱ) and 47.51 mg/g for TC ) than pristine phytolaccaceae biochar in the single system. The kinetic, isotherm and characterization analysis suggested that the inner mechanism for Pb(II) and TC removal involved electrostatic interaction, precipitation, complexation, cation exchange, pore filling, hydrogen bonding, π-π interaction and the transformation of surface MnO_x particles. Binary adsorption showed that Pb(II) would serve as a bridge between PSB450 and TC by complexation, thus facilitating their joint decontamination. While Pb(II) adsorption would be inhibited with the increasing of TC concentration due to the competition for adsorption sites. This study provided a win-win approach for reutilization of Mn-contaminated biomass and management of coexisting heavy metals and organic matters contamination in wastewater.