title: Destabilization dynamics of clay and acid-free polymers of ferric and magnesium salts in AMD without pH adjustment.
abstract: The physicochemical treatment was employed to treat acid mine drainage (AMD) in the removal of turbid materials using clay only (exp A) and a combination of clay, FeCl3 and Mg(OH)2 (exp B) to form a polymer. A 5 g sample of clay (bentonite) was added to 1.2 L of AMD and treated in a jar test at 250 rpm for 2 min and reduced to 100 rpm for 10 min. A 200 mL sub-sample from the 1.2 L mother liquor was poured into five 500 mL glass beakers, and 20 mL dosages of a polymer of 0.1 M Fe(3+) in (FeCl3) and 0.1 M Mg(2+) in (Mg(OH)2) was added to the beakers. The samples were allowed to settle for 1 h, after which the supernatant was analyzed for pH, total suspended solids (TSS), dissolved oxygen (DO) and oxidation-reduction potential (ORP) (exp A). A similar set of experiments was conducted where 200 mL of the AMD sample was poured into 500 mL glass beakers and (20-60 mL) dosages of a combination of 5 g clay, 0.1 M Fe(3+) (FeCl3) and Mg(2+) (Mg(OH)2) polymer was added and similar mixing, settling time and measurements were conducted (exp B). The polymers used in exp A exhibited TSS removal efficiency (E%) which was slightly lower compared with the polymer used in exp B, above 90%. Clay has a high TSS removal efficiency in the treatment of the AMD, indicating that adsorption was a predominant process in exps A and B. The scanning electron microscope (SEM) micrographs of the AMD sludge of both exps A and B, with a rigid and compacted structure consisting of dense flocs surrounded by the smaller flocs bound together, corroborate the fact that adsorption is a predominant process.
authors.affiliation: School of Chemical and Minerals Engineering, North West University, Faculty of Engineering, North West Province, Potchefstroom Campus, South Africa E-mail: ontwampe@gmail.com.
authors.forename: I O
authors.initials: IO
authors.lastname: Ntwampe
authors.affiliation: School of Chemical and Minerals Engineering, North West University, Faculty of Engineering, North West Province, Potchefstroom Campus, South Africa E-mail: ontwampe@gmail.com.
authors.forename: F B
authors.initials: FB
authors.lastname: Waanders
authors.affiliation: School of Chemical and Minerals Engineering, North West University, Faculty of Engineering, North West Province, Potchefstroom Campus, South Africa E-mail: ontwampe@gmail.com.
authors.forename: J R
authors.initials: JR
authors.lastname: Bunt
mesh_terms: D000327:Adsorption; D000538:Aluminum Silicates / Q000737:chemistry*; D001546:Bentonite / Q000737:chemistry; D000077215:Clay; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste / Q000032:analysis; D058085:Iron Compounds / Q000737:chemistry*; D017616:Magnesium Compounds / Q000737:chemistry*; D008906:Mining; D011108:Polymers / Q000737:chemistry*; D012722:Sewage; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D000538:Aluminum Silicates; D007220:Industrial Waste; D058085:Iron Compounds; D017616:Magnesium Compounds; D011108:Polymers; D012722:Sewage; D014874:Water Pollutants, Chemical; D001546:Bentonite; D000077215:Clay