Please use this identifier to cite or link to this item: http://hdl.handle.net/10397/33002
Title: Effects of solution chemistry on arsenic(V) removal by low-cost adsorbents
Authors: Wang, Y
Tsang, DCW 
Keywords: Adsorption
Arsenic
Coal fly ash
Green waste compost
Lignite
Issue Date: 2013
Publisher: Elsevier
Source: Journal of environmental sciences, 2013, v. 25, no. 11, p. 2291-2298 How to cite?
Journal: Journal of environmental sciences 
Abstract: Natural and anthropogenic arsenic (As) contamination of water sources pose serious health concerns, especially for small communities in rural areas. This study assessed the applicability of three industrial byproducts (coal fly ash, lignite, and green waste compost) as the low-cost adsorbents for As(V) removal under various field-relevant conditions (dissolved oxygen, As(V)/Fe ratio, solution pH, and presence of competing species). The physico-chemical properties of the adsorbents were characterized by XRD, XRF, FT-IR, and NMR analysis. Batch experiments demonstrated that coal fly ash could provide effective As(V) removal (82.1%-95%) because it contained high content of amorphous iron/aluminium hydroxides for As(V) adsorption and dissolvable calcium minerals for calcium arsenate precipitation. However, the addition of lignite and green waste compost was found unfavourable since they hindered the As(V) removal by 10%-42% possibly due to dissolution of organic matter and ternary arsenate-iron-organic matter complexes. On the other hand, higher concentrations of dissolved iron (comparing As(V)/Fe ratios of 1:1 and 1:10) and dissolved oxygen (comparing 0.2 and 6 mg/L) only marginally enhanced the As(V) removal at pH 6 and 8. Thus, addition of dissolved iron, water aeration, or pH adjustment became unnecessary because coal fly ash was able to provide effective As(V) removal under the natural range of geochemical conditions. Moreover, the presence of low levels of background competing (0.8 or 8 mg/L of humic acid, phosphate, and silicate) imposed little influence on As(V) removal, possibly because the high adsorption capacity of coal fly ash was far from exhaustion. These results suggested that coal fly ash was a potentially promising adsorbent that warranted further investigation.
URI: http://hdl.handle.net/10397/33002
ISSN: 1001-0742
EISSN: 1878-7320
DOI: 10.1016/S1001-0742(12)60296-4
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