1. Arsenic Removal from Aqueous Solutions Using Fe3O4-HBC Composite: Effect of Calcination on Adsorbents Performance.
- Author
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Baig, Shams Ali, Sheng, TianTian, Sun, Chen, Xue, XiaoQin, Tan, LiSha, and Xu, XinHua
- Subjects
ARSENIC removal (Water purification) ,HEALTH risk assessment ,CALCINATION (Heat treatment) ,SORBENTS ,IRON oxides ,COMPOSITE materials - Abstract
The presence of elevated concentration of arsenic in water sources is considered to be health hazard globally. Calcination process is known to change the surface efficacy of the adsorbent. In current study, five adsorbent composites: uncalcined and calcined Fe
3 O4 -HBC prepared at different temperatures (400°C and 1000°C) and environment (air and nitrogen) were investigated for the adsorptive removal of As(V) and As(III) from aqueous solutions determining the influence of solution's pH, contact time, temperature, arsenic concentration and phosphate anions. Characterizations from FTIR, XRD, HT-XRD, BET and SEM analyses revealed that the Fe3 O4 -HBC composite at higher calcination temperature under nitrogen formed a new product (fayalite, Fe2 SiO4 ) via phase transformation. In aqueous medium, ligand exchange between arsenic and the effective sorbent site ( = FeOOH) was established from the release of hydroxyl group. Langmuir model suggested data of the five adsorbent composites follow the order: Fe3 O4 -HBC-1000°C(N2 )>Fe3 O4 -HBC (uncalcined)>Fe3 O4 -HBC-400°C(N2 )>Fe3 O4 -HBC-400°C(air)>Fe3 O4 -HBC-1000°C(air) and the maximum As(V) and As(III) adsorption capacities were found to be about 3.35 mg g−1 and 3.07 mg g−1 , respectively. The adsorption of As(V) and As(III) remained stable in a wider pH range (4–10) using Fe3 O4 -HBC-1000°C(N2 ). Additionally, adsorption data fitted well in pseudo-second-order (R2 >0.99) rather than pseudo-first-order kinetics model. The adsorption of As(V) and As(III) onto adsorbent composites increase with increase in temperatures indicating that it is an endothermic process. Phosphate concentration (0.0l mM or higher) strongly inhibited As(V) and As(III) removal through the mechanism of competitive adsorption. This study suggests that the selective calcination process could be useful to improve the adsorbent efficiency for enhanced arsenic removal from contaminated water. [ABSTRACT FROM AUTHOR]- Published
- 2014
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