Abstract
Anthropogenic activities can lead to elevated concentrations of potentially toxic elements (PTEs) in soil and water. Thus, the search for low-cost, ecofriendly and innovative sorbents is a global necessity. The present investigation addresses the performance of peat and compost derived from the organic fraction of municipal solid waste (OFMSW) as a sorbent of zinc (Zn), lead (Pb) and cadmium (Cd). The physicochemical features and effects of the initial concentration (equilibrium) and contact time (kinetic) were systematically analyzed by batch experiments. In addition, human bioaccessibility tests were conducted to compare the human health risk of these PTEs postsorption. The results showed that the sorption capacities followed the order: compost(Pb) > peat(Pb) > compost(Cd) > compost(Zn) > peat(Cd) > peat(Zn), indicating that compost had a better sorption potential. Kinetic data were well-fitted to the pseudo-first-order (PSO), pseudo-second-order (PFO), and Elovich equation models. The external diffusion model proposed by Mathews and Weber (M&W) indicated the contribution of diffusion as a sorption mechanism, mainly in the sorption of Zn, Pb and Cd onto compost and Pb onto peat. The bioaccessible fractions in the first stage (stomach conditions) were greater than those in the second phase (intestinal simulation). Pb has higher sorption capacities (10.511 and 7.778 mg g−1 for compost and peat, respectively) and lowers fraction bioaccessible (35 to 70%). These findings demonstrate that utilizing these low-cost sorbents seems promising for the remediation of PTE soils and contaminated waters. However, more experiments should be conducted, including desorption and multielement solutions, as well as field-tests to prove the long-term effects of application in large-scale and real conditions.
Highlights
Anthropogenic activities can lead to elevated concentrations of potentially toxic elements (PTEs) in soil and water
The compost pH was higher than the peat pH (Table 1), and the values were within the expected range for these materials
In this research, the objective was to assess the behavior of the compost and peat under original conditions; pH variations were not assessed and the pH values were not adjusted at any time during the batch equilibrium test
Summary
Anthropogenic activities can lead to elevated concentrations of potentially toxic elements (PTEs) in soil and water. Pb has higher sorption capacities (10.511 and 7.778 mg g−1 for compost and peat, respectively) and lowers fraction bioaccessible (35 to 70%). These findings demonstrate that utilizing these low-cost sorbents seems promising for the remediation of PTE soils and contaminated waters. Soil is an integral system in dynamic balance with the environmental compartments of the hydrosphere, biosphere and atmosphere It is considered a multicomponent and complex system because the different phases (gas, fluid, and solid phases) are formed by organic and inorganic compounds that interact among themselves. Sustainability 2021, 13, 12847 the main cause responsible for the deterioration of groundwater because upon reaching the ground, contaminants that are not retained by the surface layers can penetrate and reach the groundwater, where they can spread, due to hydrodynamic dispersion, to increasingly distant sites [4]
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