title: Arsenic binding mechanisms on natural red earth: a potential substrate for pollution control.
abstract: Natural red earth (hereafter NRE) was used as a novel adsorbent to examine its retention behaviour in different inorganic arsenic species (As (III) and As (V)) that are abundant in natural water. Adsorption isotherms were constructed at pH approximately 5.5 for As(III) and As(V) in 0.01 M NaNO(3) at 298K for 5 g/L NRE system. The initial arsenic [As(III) or As(V)] concentrations varied between approximately 10(-5) and approximately 10(-4) M. The experimental data were quantified using single site or stepwise Langmuir models. Sorption maximum, was observed at approximately 0.173 mM of As(V). To reach the maximum surface coverage of red earth at pH approximately 5.5 As(III) requires approximately 0.308 mM of initial loading. When compared to As (III), As(V) shows strong affinity for NRE surface sites. This study suggests the potential of NRE as a starting material in decontaminating water polluted with As species.
authors.affiliation: Chemical Modelling Laboratory, Institute of Fundamental Studies, Kandy, Sri Lanka. meththikav@yahoo.com
authors.forename: Meththika
authors.initials: M
authors.lastname: Vithanage
authors.forename: Wasana
authors.initials: W
authors.lastname: Senevirathna
authors.forename: Rohana
authors.initials: R
authors.lastname: Chandrajith
authors.forename: Rohan
authors.initials: R
authors.lastname: Weerasooriya
mesh_terms: D000327:Adsorption; D001149:Arsenates / Q000737:chemistry*; D001151:Arsenic / Q000737:chemistry*; D018053:Arsenites / Q000737:chemistry*; D008956:Models, Chemical; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D014876:Water Pollution / Q000517:prevention & control; D018508:Water Purification / Q000379:methods*
chemical_list: D001149:Arsenates; D018053:Arsenites; D014874:Water Pollutants, Chemical; C015001:arsenite; D001151:Arsenic; C025657:arsenic acid