Mdlalose, Lindani MBalogun, Mohammed OSetshedi, Katlego ZChimuka, LChetty, Avashnee2021-02-182021-02-182020-08Mdlalose, L.M., Balogun, M.O., Setshedi, K.Z., Chimuka, L. & Chetty, A. 2020. Performance evaluation of polypyrrole-montmorillonite clay composite as a re-usable adsorbent for Cr(VII) remediation. <i>Polymer Bulletin, https://doi.org/10.1007/s00289-020-03338-6.</i> http://hdl.handle.net/10204/117910170-08391436-2449http://hdl.handle.net/10204/11791A flexible composite adsorbent combination of polypyrrole and montmorillonite clay (PPy-MMT) has been prepared by in situ oxidative polymerization method. This well-achieved adsorbent has amphoteric characteristics and has been explored in many adsorption processes related to heavy metals removal, more especially Cr(VI) from the water phase. However, the progressive accumulation of Cr(VI) onto the adsorbent surface reduces its adsorption capacity before adsorbent depletion. This factor limits the application of the adsorbent due to high cost and environmental impact related to adsorbent disposal after use. Here, we report the feasibility of different regenerating agents to recover adsorbed Cr(VI) and activate the tunable surface charge of the adsorbent composite to restore its initial adsorption capacity until exhaustion. The recycled PPy-MMT adsorbents were characterized by FTIR, TGA and EDS analysis. At low solution pH, PPy-MMT is protonated resulting in high adsorption capacity for Cr(VI) through electrostatic attraction and ion exchange while simultaneously reducing Cr(VI) to less toxic Cr(III). The spent adsorbents were reversibly subjected to sequential adsorption–desorption cycles between adsorbent neutral state and the oxidized state using different concentrations of regenerating agents including NaOH, NH4OH, HCl, NH4Cl and HNO3, respectively. The results suggested that with 0.01 M NaOH and 0.5 M HCl, PPy-MMT could be used for over five cycles for Cr(VI) removal with more than 80% regeneration efficiency indicating potential applicability as a re-usable adsorbent for Cr(VI) removal.AbstractenPolymer compositesDesorption parametersRegenerationSurface chargeArticleMdlalose, L. M., Balogun, M. O., Setshedi, K. Z., Chimuka, L., & Chetty, A. (2020). Performance evaluation of polypyrrole-montmorillonite clay composite as a re-usable adsorbent for Cr(VII) remediation. <i>Polymer Bulletin, https://doi.org/10.1007/s00289-020-03338-6</i>, http://hdl.handle.net/10204/11791Mdlalose, Lindani M, Mohammed O Balogun, Katlego Z Setshedi, L Chimuka, and Avashnee Chetty "Performance evaluation of polypyrrole-montmorillonite clay composite as a re-usable adsorbent for Cr(VII) remediation." <i>Polymer Bulletin, https://doi.org/10.1007/s00289-020-03338-6</i> (2020) http://hdl.handle.net/10204/11791Mdlalose LM, Balogun MO, Setshedi KZ, Chimuka L, Chetty A. Performance evaluation of polypyrrole-montmorillonite clay composite as a re-usable adsorbent for Cr(VII) remediation. Polymer Bulletin, https://doi.org/10.1007/s00289-020-03338-6. 2020; http://hdl.handle.net/10204/11791.TY - Article AU - Mdlalose, Lindani M AU - Balogun, Mohammed O AU - Setshedi, Katlego Z AU - Chimuka, L AU - Chetty, Avashnee AB - A flexible composite adsorbent combination of polypyrrole and montmorillonite clay (PPy-MMT) has been prepared by in situ oxidative polymerization method. This well-achieved adsorbent has amphoteric characteristics and has been explored in many adsorption processes related to heavy metals removal, more especially Cr(VI) from the water phase. However, the progressive accumulation of Cr(VI) onto the adsorbent surface reduces its adsorption capacity before adsorbent depletion. This factor limits the application of the adsorbent due to high cost and environmental impact related to adsorbent disposal after use. Here, we report the feasibility of different regenerating agents to recover adsorbed Cr(VI) and activate the tunable surface charge of the adsorbent composite to restore its initial adsorption capacity until exhaustion. The recycled PPy-MMT adsorbents were characterized by FTIR, TGA and EDS analysis. At low solution pH, PPy-MMT is protonated resulting in high adsorption capacity for Cr(VI) through electrostatic attraction and ion exchange while simultaneously reducing Cr(VI) to less toxic Cr(III). The spent adsorbents were reversibly subjected to sequential adsorption–desorption cycles between adsorbent neutral state and the oxidized state using different concentrations of regenerating agents including NaOH, NH4OH, HCl, NH4Cl and HNO3, respectively. The results suggested that with 0.01 M NaOH and 0.5 M HCl, PPy-MMT could be used for over five cycles for Cr(VI) removal with more than 80% regeneration efficiency indicating potential applicability as a re-usable adsorbent for Cr(VI) removal. DA - 2020-08 DB - ResearchSpace DP - CSIR J1 - Polymer Bulletin, https://doi.org/10.1007/s00289-020-03338-6 KW - Polymer composites KW - Desorption parameters KW - Regeneration KW - Surface charge LK - https://researchspace.csir.co.za PY - 2020 SM - 0170-0839 SM - 1436-2449 T1 - Performance evaluation of polypyrrole-montmorillonite clay composite as a re-usable adsorbent for Cr(VII) remediation TI - Performance evaluation of polypyrrole-montmorillonite clay composite as a re-usable adsorbent for Cr(VII) remediation UR - http://hdl.handle.net/10204/11791 ER -24212