title: Adsorption/desorption of arsenic by tropical peat: influence of organic matter, iron and aluminium.
abstract: The objective of this work was to investigate the interaction of arsenic species (As(III) and As(V)) with tropical peat. Peat samples collected in Brazil were characterized using elemental analysis and 13C NMR. Adsorption experiments were performed using different concentrations of As with peat in natura and enriched with Fe or Al, at three different pH levels. Peat samples, in natura or enriched with metals, were analysed before and after adsorption processes using Fourier transform infrared spectroscopy (FTIR) spectroscopy. The adsorption kinetics was evaluated, and the data were fitted using the Langmuir and Freundlich models. The results showed that interaction between As and peat was dependent on the levels of organic matter (OM) and the metals (Fe and Al). As(III) was not adsorbed by in natura peat or Al-enriched peat, although small amounts of As(III) were adsorbed by Fe-enriched peat. Adsorption of As(V) by the different peat samples ranged from 21.3 to 52.7 μg g(-1). The best fit to the results was obtained using the pseudo-second-order kinetic model, and the adsorption of As(V) could be described by the Freundlich isotherm model. The results showed that Fe-enriched peat was most effective in immobilizing As(V). FTIR analysis revealed the formation of ternary complexes involving As(V) and peat enriched with metals, suggesting that As(V) was associated with Al or Fe-OM complexes by metal bridging.
authors.affiliation: a Institute of Chemistry , São Paulo State University (UNESP) , Rua Prof. Francisco Degni 55, Araraquara SP 18087-180 , Brazil.
authors.forename: Lílian Karla
authors.initials: LK
authors.lastname: de Oliveira
authors.forename: Camila Almeida
authors.initials: CA
authors.lastname: Melo
authors.forename: Danielle
authors.initials: D
authors.lastname: Goveia
authors.forename: Fabiana Aparecida
authors.initials: FA
authors.lastname: Lobo
authors.forename: Maria Aurora
authors.initials: MA
authors.lastname: Armienta Hernández
authors.forename: Leonardo Fernandes
authors.initials: LF
authors.lastname: Fraceto
authors.forename: André Henrique
authors.initials: AH
authors.lastname: Rosa
mesh_terms: D000327:Adsorption; D000535:Aluminum / Q000737:chemistry*; D001151:Arsenic / Q000737:chemistry / Q000302:isolation & purification*; D052918:Environmental Restoration and Remediation; D007501:Iron / Q000737:chemistry*; D009930:Organic Chemicals / Q000737:chemistry*; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000737:chemistry* / Q000302:isolation & purification*; D014462:Ultrafiltration / Q000379:methods
chemical_list: D009930:Organic Chemicals; D012987:Soil; D012989:Soil Pollutants; D000535:Aluminum; D007501:Iron; D001151:Arsenic
keywords: aluminium; arsenic; iron; organic matter; peat