Adsorption and reduction from modified polypyrrole enhance electrokinetic remediation of hexavalent chromium-contaminated soil

Abstract

Heavy metal pollutant Cr( ) in the environment will pose a severe threat to animal and human health. In this work, Fe 3 O 4 @PPy, Arg@PPy, and Arg/Fe 3 O 4 @PPy were prepared to enhance adsorption of Cr( ) by doping Fe 3 O 4 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 Crcontaminated soil. Adsorption experiment results showed that the maximum adsorption capacities of PPy, Fe 3 O 4 @PPy, Arg@PPy, and Arg/Fe 3 O 4 @PPy for Cr( ) were 60.43 mg/g, 67.12 mg/g, 159.86 mg/g, and 141.50 mg/g, respectively. All of them followed the kinetic pseudo-second-order model and the Langmuir isothermal model with a monolayer adsorption behavior. In EKR/PRB system, the presence of Fe 3 O 4 @PPy, Arg@PPy, and Arg/Fe 3 O 4 @PPy obtained the higher Cr( ) removal e ciency near the anode than that of the PPy, increasing by 74.60%, 26.04%, 68.64%, respectively. A strong electrostatic attraction between anion contaminants and protonated modi ed PPy and a reduction from Cr( ) to Cr( ) appeared in the EKR remediation process under acid conditions. This study opened up a prospect for applying modi ed PPy composites to treat heavy metal contaminated soil.

Preparation of MES@Fe3O4@SiO2-PPy magnetic microspheres for the highly efficient removal of Cr(vi)

“…34 The maximum adsorption capacities of MFSP at 298, 308, and 318 K were 301.20, 348.43, and 398.41 mg g −1 , respectively, by fitting the Langmuir isothermal model. Compared with other PPy-based magnetic adsorbents, such as PPy-PANI/Fe 3 O 4 ( Q m = 303.03 mg g −1 ), 35 PPy/Fe 3 O 4 ( Q m = 208.77 mg g −1 ), 10 PPy-mPD/Fe 3 O 4 ( Q m = 555.60 mg g −1 ), 36 magnetic UiO-66@PPy ( Q m = 259.10 mg g −1 ), 37 Arg/Fe 3 O 4 @PPy ( Q m = 141.50 mg g −1 ), 38 MFSP exhibited a relatively high adsorption capacity for Cr( vi ).…”