Synthesis of zeolitic-type adsorbent material from municipal solid waste incinerator bottom ash and its application in heavy metal adsorption

Municipal solid waste incinerator (MSWI) bottom ash (BA) was converted to zeolitic-type adsorbent materials by hydrothermal conversion under strongly alkaline conditions. The conversion product was determined to be a mixture of sodium aluminum silicate hydrate (SASH) (Na2O·Al2O3·1.68SiO2·1.73H2O) and tobermorite (Ca5Si6O16(OH)2·4H2O). The BET specific surface area was 22.1 m2/g, which represented a significant gain compared to the BA (4.6 m2/g) due to the formation of micropores and mesopores. The converted BA demonstrated promising performance for application as a sorbent towards several heavy metals (oxyanions of As(V), and Cd2+, Co2+, Ni2+, Pb2+, and Zn2+). Its performance was found to be generally superior to that of a mainly clinoptilolite natural zeolite, achieving greater sorption extents and better stabilizing capability of contaminated sediments. At a lower dosage rate (50 mg sorbent per gram sediment) to that of natural zeolite, converted BA achieved greater than 80% reduction of cationic heavy metal concentrations in sediment porewater. These results suggest a promising route for reutilization of MSWI-BA, which can greatly enhance the sustainability of waste incineration technology.

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► Synthesis of zeolitic-type material from bottom ash and use as heavy metal sorbent.
► Hydrothermal conversion products sodium aluminum silicate hydrate and tobermorite.
► Formation of micro-/mesopores increased BET surface area from 4.6 to 22.1 m2/g.
► More than 80% reduction of Cd2+, Co2+, Ni2+, Pb2+ and Zn2+ in sediment porewater.
► Better performance (sorption and stability) than clinoptilolite natural zeolite.