Study of arsenic(III) and arsenic(V) removal from waters using ferric hydroxide supported on silica gel prepared at low pH

Removal of As(III) and As(V) species using ferric hydroxide supported on silica gel was studied. Laboratory reagent quality silica gel was used as to avoid uncertainties that may be caused by impurities. Ferric hydroxide precipitation was realized at various pH values and a relatively low pH 6.0 was...

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Bibliographic Details
Published in:Environmental technology 2011-01, Vol.32 (3), p.341-351
Main Authors: Çiftçi, Tülin Deniz, Yayayürük, Onur, Henden, Emür
Format: Article
Language:English
Subjects:
Adsorption
Applied sciences
Arsenates - chemistry
Arsenic
Arsenic removal
Arsenites - chemistry
Chemical engineering
chemical precipitation
chemical speciation
Drinking water
Drinking water and swimming-pool water. Desalination
environmental technology
Exact sciences and technology
Ferric Compounds - chemistry
Ferric hydroxide
geothermal water
Hydrogen-Ion Concentration
ions
Iron
Microscopy, Electron, Scanning
mineral water
oxidation
Pollution
Precipitation
Reactors
Silica gel
Silica Gel - chemistry
Sorbents
Speciation
Water Pollutants, Chemical - chemistry
water treatment
Water treatment and pollution
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Summary:Removal of As(III) and As(V) species using ferric hydroxide supported on silica gel was studied. Laboratory reagent quality silica gel was used as to avoid uncertainties that may be caused by impurities. Ferric hydroxide precipitation was realized at various pH values and a relatively low pH 6.0 was chosen because, at this pH, the highest arsenic removal capacity and removal efficiency were obtained and clear supernatant solution was observed. It was also shown by arsenic speciation analysis at trace level that As(III) is adsorbed onto ferric hydroxide partly without oxidation to As(V); this has been a controversial point in the literature. The effects on arsenic removal of some parameters such as pH, flow rate and matrix ions were investigated. In the batch method, initial pH change of the solution did not significantly affect the arsenic removal efficiencies for As(III) and As(V) in the pH range of 3.1–9.7. This was attributed to the decreases of the initial pH values to around 5 at equilibrium. The column capacities of 1.32 mg As(III)/g sorbent and 1.21 mg As(V)/g sorbent were found for initial concentration of 1.00 mg/L arsenic. Batch capacities were 16.2 mg As(III)/g sorbent and 17.7 mg As(V)/g sorbent for initial arsenic concentration of 100 mg/L. The method was applied successfully to the removal of As(III) and As(V) from drinking water, geothermal water and mineral water.
ISSN:1479-487X
0959-3330
1479-487X
DOI:10.1080/09593330.2010.499546