Sorption and economic viability of peat, compost and biochar for zinc-contaminated site

Abstract

The growing demand for low-cost sorbents, which guarantee eco-efficiency in removing contaminants, has led to numerous studies in recent decades. In this sense, sorbents derived from organic residues have shown promising options; however, the organic fraction of municipal solid waste (OFMSW) has received little attention to date. This study compares the zinc (Zn) sorption performance of a traditional sorbent (peat) with that of materials derived from OFMSW (compost and biochar). According to the Langmuir model, biochar showed the highest sorption capacity (53.494 mg/g), followed by compost (37.569 mg/g) and peat (5.842 mg/g). Although the maximum sorption capacities adjusted by linear and non-linear regressions were close, the values were relevant only when they would have reached the saturation plateau. The cost estimate of the studied sorbents validated their economic viability with that of commercially available ones. The findings provide a theoretical basis for a better understanding of sorption experiments, from the choice of initial concentrations to the isothermal modelling of the results, for comparative evaluation of potential sorbents for the remediation of soils and waters contaminated with potentially toxic metals, such as zinc.