Abstract
Toxic metal pollutant Cr(VI) in the environment will pose a severe threat to animal and human health. In this work, Fe3O4@PPy, Arg@PPy, and Arg/Fe3O4@PPy were prepared to enhance adsorption of Cr(VI) by doping Fe3O4 nanoparticles and amino radicals into the original PPy structure. Their characteristics were investigated by FTIR, SEM, EDS, BET analysis, and batch adsorption experiments. And they were used as permeable reaction barriers (PRB) to combine with electrokinetic remediation (EKR) to remediate Cr-contaminated soil. Adsorption experiment results showed that the maximum adsorption capacities of PPy, Fe3O4@PPy, Arg@PPy, and Arg/Fe3O4@PPy for Cr(VI) were 60.43mg/g, 67.12mg/g, 159.86mg/g, and 141.50mg/g, respectively. They all followed the kinetic pseudo-second-order model and the Langmuir isothermal model with a monolayer adsorption behavior. In the EKR/PRB system, the presence of Fe3O4@PPy, Arg@PPy, and Arg/Fe3O4@PPy obtained the higher Cr(VI) removal efficiency near the anode than that of the PPy, increasing by 74.60%, 26.04%, and 68.64%, respectively. A strong electrostatic attraction between anion contaminants and protonated modified PPy and a reduction from Cr(VI) to Cr(III) appeared in the EKR remediation process under acid conditions. This study opened up a prospect for applying modified PPy composites to treat toxic metal-contaminated soil.
Highlights
Recent developments in industrialization have heightened the emphasis on soil contamination by heavy metals (Sarwar et al 2017)
Fe3O4@PPy, arginine modified PPy (Arg@PPy), and Arg/Fe3O4@PPy were prepared to enhance adsorption of Cr(VI) by doping Fe3O4 nanoparticles and amino radicals into the original PPy structure. Their characteristics were investigated by FTIR, SEM, EDS, BET analysis, and batch adsorption experiments. They were used as permeable reaction barriers (PRB) to combine with electrokinetic remediation (EKR) to remediate Crcontaminated soil
Adsorption experiment results showed that the maximum adsorption capacities of PPy, Fe3O4@PPy, Arg@PPy, and Arg/Fe3O4@PPy for Cr(VI) were 60.43 mg/g, 67.12 mg/g, 159.86 mg/g, and 141.50 mg/g, respectively
Summary
Recent developments in industrialization have heightened the emphasis on soil contamination by heavy metals (Sarwar et al 2017). The research to date about industrial chromium (Cr) pollution is considered to put an increasing burden on the environment and human health (Wang et al 2019). Published studies have shown that Cr exists in nature mainly as two stable oxidation states, including hexavalent chromium and trivalent chromium (Sarin &Pant 2006). Cr(VI) usually occurs as anionic species such as CrO42−, HCrO4−, and Cr2O72−, which have high mobility in soil and groundwater, resulting in potential danger of toxicity and carcinogenicity (Eyvazi et al 2019). Cr(III) species, like Cr3+, Cr3(OH)45+, and Cr(OH)2+, are less toxic and more stable than Cr(VI) (Sarin &Pant 2006).
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