Arsenic removal from soil with high iron content using a natural surfactant and phosphate
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An environment friendly arsenic removal technique from contaminated soil with high iron content has been studied. A natural surfactant extracted from soapnut fruit, phosphate solution and their mixture was used separately as extractants. The mixture was most effective in desorbing arsenic, attaining above 70 % efficiency in the pH range of 4–5. Desorption kinetics followed Elovich model. Micellar solubilization by soapnut and arsenic exchange mechanism by phosphate are the probable mechanisms behind arsenic desorption. Sequential extraction reveals that the mixed soapnut–phosphate system is effective in desorbing arsenic associated with amphoteric–Fe-oxide forms. No chemical change to the wash solutions was observed by Fourier transform-infrared spectra. Soil:solution ratio, surfactant and phosphate concentrations were found to affect the arsenic desorption process. Addition of phosphate boosted the performance of soapnut solution considerably. Response surface methodology approach predicted up to 80 % desorption of arsenic from soil when treated with a mixture of ≈1.5 % soapnut, ≈100 mM phosphate at a soil:solution ratio of 1:30.
KeywordsSoil washing Soapnut Phosphate Sapindus mukorossi Arsenic
The authors acknowledge the funding provided by University of Malaya, Kuala Lumpur (Grant nos: PV102-2011A and UM-QUB6A-2011) for carrying out this research.
- Antony J (2003) Design of experiments for engineers and scientists. Butterworth-Heinemann, New YorkGoogle Scholar
- Chapman HD (1965) Cation-exchange capacity, vol 9. Methods of soil analysis: chemical and microbiological properties. AgronomyGoogle Scholar
- Chowdhury TR, Basu GK, Mandal BK, Biswas BK, Samanta G, Chowdhury UK, Chanda CR, Lodh D, Roy SL, Saha KC, Roy S, Kabir S, Quamruzzaman Q, Chakraborti D (1999) Arsenic poisoning in the Ganges delta. Nature 401(6753):545–546Google Scholar
- Kommalapati RR, Roy D (1996) Bioenhancement of soil microorganisms in natural surfactant solutions: I. Aerobic. J Environ Sci Health Part A 31:1951–1964Google Scholar
- Raatz S, Härtel G (1996) Application of surfactant combinations for cleaning clays contaminated with polycyclic aromatic hydrocarbons. Anwendung von tensidkombinationen zur reinigung PAK-kontaminierter tone 37(2):57–62Google Scholar
- Saxena D, Pal R, Dwivedi AK, Singh S (2004) Characterization of sapindosides in Sapindus mukorossi saponin (reetha saponin) and quantitative determination of sapindoside B. J Sci Ind Res 63:181–186Google Scholar
- Suhagia BN, Rathod IS, Sindhu S (2011) Sapindus mukorossi (Areetha): an overview. Int J Pharm Sci Res 2(8):1905–1913Google Scholar
- Weng H, Liu Y, Chen H (1997) Environmental geochemical features of arsenic in soil in China. J Environ Sci (China) 9(4):385–395Google Scholar