title: Characterization of carbonated tricalcium silicate and its sorption capacity for heavy metals: a micron-scale composite adsorbent of active silicate gel and calcite.
abstract: Adsorption-based processes are widely used in the treatment of dilute metal-bearing wastewaters. The development of versatile, low-cost adsorbents is the subject of continuing interest. This paper examines the preparation, characterization and performance of a micro-scale composite adsorbent composed of silica gel (15.9 w/w%), calcium silicate hydrate gel (8.2 w/w%) and calcite (75.9 w/w%), produced by the accelerated carbonation of tricalcium silicate (C(3)S, Ca(3)SiO(5)). The Ca/Si ratio of calcium silicate hydrate gel (C-S-H) was determined at 0.12 (DTA/TG), 0.17 ((29)Si solid-state MAS/NMR) and 0.18 (SEM/EDS). The metals-retention capacity for selected Cu(II), Pb(II), Zn(II) and Cr(III) was determined by batch and column sorption experiments utilizing nitrate solutions. The effects of metal ion concentration, pH and contact time on binding ability was investigated by kinetic and equilibrium adsorption isotherm studies. The adsorption capacity for Pb(II), Cr(III), Zn(II) and Cu(II) was found to be 94.4 mg/g, 83.0 mg/g, 52.1 mg/g and 31.4 mg/g, respectively. It is concluded that the composite adsorbent has considerable potential for the treatment of industrial wastewater containing heavy metals.
authors.affiliation: School of Environmental Science and Engineering, Donghua University, Shanghai, PR China. qychen@dhu.edu.cn
authors.forename: Quanyuan
authors.initials: Q
authors.lastname: Chen
authors.forename: Colin D
authors.initials: CD
authors.lastname: Hills
authors.forename: Menghong
authors.initials: M
authors.lastname: Yuan
authors.forename: Huanhuan
authors.initials: H
authors.lastname: Liu
authors.forename: Mark
authors.initials: M
authors.lastname: Tyrer
mesh_terms: D000327:Adsorption; D002119:Calcium Carbonate / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D019216:Metals, Heavy / Q000737:chemistry*; D058428:Silica Gel; D017640:Silicates / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods
chemical_list: D017610:Calcium Compounds; D019216:Metals, Heavy; D017640:Silicates; D014874:Water Pollutants, Chemical; C506393:tricalcium silicate; D058428:Silica Gel; D002244:Carbon; D012822:Silicon Dioxide; D002119:Calcium Carbonate