title: Stabilization of Cr(VI) from fine ferrochrome dust using exfoliated vermiculite.
abstract: This study proved that vermiculite, a natural occurring mineral, can effectively remove and stabilize Cr(VI) from fine ferrochrome dust leachate. Batch adsorption studies were carried out to determine the effect of pH, contact time and adsorbent dose on the removal of Cr(VI). The process was found to be highly pH dependent. The optimum conditions for the Cr(VI) removal are at a pH of 1.5, contact time of 2h and adsorbent dose of 10gL(-1). The stability of the Cr(VI)-loaded vermiculite remained unchanged after 12 months, when the vermiculite was evaluated with the ASTM and TCLP Cr(VI) leach methods. However, Cr(VI) desorption did take place when the Acid Rain Test was used. The adsorption kinetic data fits the pseudo-second order model, while the equilibrium data of Cr(VI) adsorption onto vermiculite are best described by the Langmuir isotherm. The presence of hydrobiotite and biotite in the industrial vermiculite slightly decreased the degree of adsorption of Cr(VI).
authors.affiliation: Department of Materials Science and Metallurgical Engineering, University of Pretoria, Pretoria 0002, South Africa. delmulange@tuks.co.za
authors.forename: Delphin
authors.initials: D
authors.lastname: Mulange Wa Mulange
authors.forename: Andrie Mariana
authors.initials: AM
authors.lastname: Garbers-Craig
mesh_terms: D000327:Adsorption; D000538:Aluminum Silicates / Q000737:chemistry*; D002857:Chromium / Q000302:isolation & purification*; D002858:Chromium Alloys / Q000737:chemistry*; D004391:Dust / Q000032:analysis*; D004785:Environmental Pollutants / Q000302:isolation & purification*; D052918:Environmental Restoration and Remediation; D006863:Hydrogen-Ion Concentration; D008906:Mining; D008956:Models, Chemical; D012996:Solutions; D013019:South Africa; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction
chemical_list: D000538:Aluminum Silicates; D002858:Chromium Alloys; D004391:Dust; D004785:Environmental Pollutants; D012996:Solutions; D002857:Chromium; C027393:ferrochromium; C003760:vermiculite; C074702:chromium hexavalent ion