Eco-friendly ceramsite from dredged sediment/biomass for Pb(II) removal: Process optimization and adsorption mechanistic insights

The disposal of dredged sediment (DS) is a challenge because of its output and ecotoxicity. Highly toxic Pb(II) enriched in aquatic environment has become a severe global issue. In this study, we developed a new type of ceramsite by co-utilizing of DS and rice husk (RH) to remove Pb(II) from aquatic environments from the viewpoint of using waste to treat waste. Optimized ceramsite (D9R1-C) sintered at 1120 degrees C with 10% RH additive, exhibited excellent adsorption potential and environmental friendliness. RH addition was an essential component in obtaining ceramsite with richer pore structures, higher polymerization degree and more zeolite serials contents. D9R1-C had selective adsorption to Pb(II), with a maximum adsorption capacity of 18.53 mg/g. The incorporation of adsorption kinetics, isotherms, and thermodynamics, it indicated that adsorption behavior of D9R1-C was codetermined by physisorption and chemisorption. Between the two, physisorption was uppermost. The detailed adsorption mechanism was summarized as follows: (1) physisorption occurred in the intersurface and pore structure of the sorbent; (2) Si-O-T or -OH bond from gismondine or gismondine-like phases combined with Pb(II) to form a stable Si-O-Pb bond; (3) Pb(II) disintegrated the skeleton structure of zeolite serials and then reacted with decomposed units to form Pb-containing minerals such as alamosite.

Automated summary

A new type of ceramsite was developed in this study by co-utilizing dredged sediment (DS) and rice husk (RH) to remove Pb(II) from aquatic environments. The optimized ceramsite exhibited excellent adsorption potential and environmental friendliness. The adsorption mechanism involved both physisorption and chemisorption processes.