title: Removal of hexavalent chromium from aqueous solutions using micro zero-valent iron supported by bentonite layer.
abstract: Hexavalent chromium Cr(VI) is of particular environmental concern due to its toxicity, mobility, and challenging removal from industrial wastewater. It is a strong oxidizing agent that is carcinogenic and mutagenic and diffuses quickly through soil and aquatic environments. Moreover, it does not form insoluble compounds in aqueous solutions; therefore, separation by precipitation is not feasible. While Cr(VI) oxyanions are very mobile and toxic in the environment, trivalent Cr(III) cations are the opposite and, like many metal cations, Cr(III) forms insoluble precipitates. Thus, reducing Cr(VI)-Cr(III) simplifies its removal from effluent and also reduces its toxicity and mobility. Permeable reactive barriers (PRBs) with zero-valent iron (ZVI) have been used to remediate contaminated groundwater with metals, but using ZVI in remediation of contaminated groundwater or wastewater is limited due to its lack of stability, easy aggregation, and difficulty in separation of iron from the treated solution. Thus, the technology used in the present study is developed to address these problems by placing a layer of bentonite after the PRB layer to remove iron from the treated water. The removal rates of Cr(VI) under different values of pH were investigated, and the results indicated the highest adsorption capacity at low pH.
authors.affiliation: Department of Civil and Environmental Engineering, Amirkabir University of Technology (Tehran Polytechnic), Hafez St, Tehran 15875-4413, Iran E-mail: tebadi@aut.ac.ir.
authors.forename: Waseem
authors.initials: W
authors.lastname: Daoud
authors.affiliation: Department of Civil and Environmental Engineering, Amirkabir University of Technology (Tehran Polytechnic), Hafez St, Tehran 15875-4413, Iran E-mail: tebadi@aut.ac.ir.
authors.forename: Taghi
authors.initials: T
authors.lastname: Ebadi
authors.affiliation: Department of Civil and Environmental Engineering, Amirkabir University of Technology (Tehran Polytechnic), Hafez St, Tehran 15875-4413, Iran E-mail: tebadi@aut.ac.ir.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Fahimifar
mesh_terms: D000327:Adsorption; D001546:Bentonite / Q000737:chemistry*; D002857:Chromium / Q000302:isolation & purification*; D004867:Equipment Design; D060587:Groundwater / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D062065:Wastewater / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000302:isolation & purification; D018508:Water Purification / Q000295:instrumentation / Q000379:methods*
chemical_list: D001546:Bentonite; D002857:Chromium; D007501:Iron; D062065:Wastewater; D014874:Water Pollutants, Chemical; C074702:chromium hexavalent ion