title: Arsenate removal by layered double hydroxides embedded into spherical polymer beads: Batch and column studies.
abstract: In this study, the performance of poly(layered double hydroxides) [poly(LDHs)] beads as an adsorbent for arsenate removal from aqueous solution was investigated. The poly(LDHs) beads were prepared by immobilizing LDHs into spherical alginate/polyvinyl alcohol (PVA)-glutaraldehyde beads (spherical polymer beads). Batch adsorption studies were conducted to assess the effect of contact time, solution pH, initial arsenate concentrations and co-existing anions on arsenate removal performance. The potential reuse of these poly(LDHs) beads was also investigated. Approximately 79.1 to 91.2% of arsenic was removed from an arsenate solution (50 mg As L(-1)) by poly(LDHs). The adsorption data were well described by the pseudo-second-order kinetics model and the Langmuir isotherm model, and the adsorption capacities of these poly(LDHs) beads at pH 8 were from 1.64 to 1.73 mg As g(-1), as calculated from the Langmuir adsorption isotherm. The adsorption ability of the poly(LDHs) beads decreased by approximately 5-6% after 5 adsorption-desorption cycles. Phosphates markedly decreased arsenate removal. The effect of co-existing anions on the adsorption capacity declined in the following order: HPO4 (2-) >> HCO3 (-) > SO4 (2-) > Cl(-). A fixed-bed column study was conducted with real-life arsenic-containing water. The breakthrough time was found to be from 7 to 10 h. Under optimized conditions, the poly(LDHs) removed more than 82% of total arsenic. The results obtained in this study will be useful for further extending the adsorbents to the field scale or for designing pilot plants in future studies. From the viewpoint of environmental friendliness, the poly(LDHs) beads are a potential cost-effective adsorbent for arsenate removal in water treatment.
authors.affiliation: a Institute of Chemical Technology, Vietnam Academy of Science and Technology , Ho Chi Minh City , Vietnam.|b Department of Chemistry , University of Science, Vietnam National University , Ho Chi Minh City , Vietnam.
authors.forename: Ho Nguyen
authors.initials: HN
authors.lastname: Nhat Ha
authors.affiliation: a Institute of Chemical Technology, Vietnam Academy of Science and Technology , Ho Chi Minh City , Vietnam.
authors.forename: Nguyen Thi
authors.initials: NT
authors.lastname: Kim Phuong
authors.affiliation: a Institute of Chemical Technology, Vietnam Academy of Science and Technology , Ho Chi Minh City , Vietnam.
authors.forename: Tran
authors.initials: T
authors.lastname: Boi An
authors.affiliation: c Department of Chemical Technology , Industrial University of Ho Chi Minh , Ho Chi Minh City , Vietnam.
authors.forename: Nguyen Thi
authors.initials: NT
authors.lastname: Mai Tho
authors.affiliation: c Department of Chemical Technology , Industrial University of Ho Chi Minh , Ho Chi Minh City , Vietnam.
authors.forename: Tran
authors.initials: T
authors.lastname: Ngoc Thang
authors.affiliation: d Institute of Environmental Technology, Vietnam Academy of Science and Technology , Ho Chi Minh City , Vietnam.
authors.forename: Bui
authors.initials: B
authors.lastname: Quang Minh
authors.affiliation: e Department of Chemical and Food Engineering , Lac Hong University , Bien Hoa , Vietnam.
authors.forename: Cao
authors.initials: C
authors.lastname: Van Du
mesh_terms: D000327:Adsorption; D001149:Arsenates / Q000737:chemistry*; D006878:Hydroxides / Q000737:chemistry*; D008962:Models, Theoretical; D011108:Polymers / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D001149:Arsenates; D006878:Hydroxides; D011108:Polymers; D014874:Water Pollutants, Chemical
keywords: Adsorption isotherm; Poly(LDHs) beads; adsorption kinetics; arsenate removal; fixed-bed column; regeneration