title: Removal of Co(II) and Ni(II) ions from contaminated water using silica gel functionalized with EDTA and/or DTPA as chelating agents.
abstract: In this study, the removal of Co(II) and Ni(II) ions from contaminated water was investigated using silica gel materials functionalized with both ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA). The modified adsorbents were characterized using elemental analysis, surface area and pore size analysis, and zeta potential analysis. The adsorption and regeneration studies were conducted in batch mode. The optimum conditions for the removal of both metals at an initial concentration of 10mg/L were 2g/L of dose, pH 3, 50 rpm of agitation speed and 4h of contact time. The removal of Co(II) and Ni(II) by EDTA- and/or DTPA-modified silica gels was substantially higher than that by their unmodified form. The maximum Co(II) and Ni(II) uptakes by the EDTA-modified silica gel were 20.0 and 21.6 mg/g, comparable to their adsorption capacities by DTPA-modified silica gel (Co(II): 16.1mg/g; Ni(II): 16.7 mg/g). At the same concentration of 10mg/L, the removal of both metals by the modified adsorbents ranged from 96% to 99%. The two-site Langmuir model was representative to simulate adsorption isotherms. The kinetics of Co(II) and Ni(II) adsorption by modified silica gels followed pseudo-second-order.
authors.affiliation: Department of Environmental Science, Laboratory of Applied Environmental Chemistry, The University of Kuopio, FI-50100 Mikkeli, Finland. Eveliina.repo@uku.fi
authors.forename: Eveliina
authors.initials: E
authors.lastname: Repo
authors.forename: Tonni Agustiono
authors.initials: TA
authors.lastname: Kurniawan
authors.forename: Jolanta K
authors.initials: JK
authors.lastname: Warchol
authors.forename: Mika E T
authors.initials: ME
authors.lastname: Sillanpää
mesh_terms: D000327:Adsorption; D002614:Chelating Agents / Q000737:chemistry*; D003035:Cobalt / Q000737:chemistry / Q000302:isolation & purification*; D004492:Edetic Acid / Q000737:chemistry*; D052918:Environmental Restoration and Remediation; D005782:Gels; D006863:Hydrogen-Ion Concentration; D019216:Metals, Heavy / Q000737:chemistry / Q000302:isolation & purification; D009532:Nickel / Q000737:chemistry / Q000302:isolation & purification*; D004369:Pentetic Acid / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D013997:Time Factors; D014865:Waste Disposal, Fluid / Q000379:methods; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*
chemical_list: D002614:Chelating Agents; D005782:Gels; D019216:Metals, Heavy; D014874:Water Pollutants, Chemical; D003035:Cobalt; D012822:Silicon Dioxide; D004369:Pentetic Acid; D009532:Nickel; D004492:Edetic Acid