REMOVAL OF ARSENIC (V) FROM WATER BY ADSORPTION ONTO LOW-COST AND WASTE MATERIALS

Sridhar Rao .T, Srinivasa Murthy.D

Abstract: In the present study, waste and low-cost materials like Cast-Iron Filings (wastes from mechanical workshops, lathes) and Steel Wool (commercially available, used for cleaning of wood surfaces prior to polishing) were investigated to assess their potential for removal of Arsenic from water by the process of adsorption by conducting different types of batch adsorption experiments, continuous flow column studies and candle filter studies. Batch sorption experiments brought forth the effectiveness of sorbent materials for removal of Arsenic from water achieving a removal of 90-95% at favorable pH conditions which lie in the normal range. Isothermal equilibrium data fitted well into the Langmuir model suggesting formation of unimolecular monolayer of sorbate over a homogenous surface of uniform energy. Both desorption studies and the shape of the saturation curves denote high affinity of the sorbent for the sorbate. Regeneration studies indicate repeated regeneration of the sorbents thus extending the usage of the sorbent following regenerations. While sulfates, Fluoride and chlorides have little influence on sorptive removal, phosphates and silicates exercise considerable influence by reducing removal. Fixed bed continuous down-flow column studies conducted using ground water spiked with 300ug/l Arsenic (V) at flow rates of 5.0 and 10.0 ml/min indicated the usefulness of the sorbents for engineering applications for removal of Arsenic from water. Candle filter studies conducted by filling the hollow portion of the candles used in the domestic filters filled with sorbent material further demonstrated the utility of the existing household filters for removal of Arsenic (V) to less than the permissible limits of BIS/WHO by simply filling the hollow portion with the sorbent material. No leaching of Iron was found in the filtered water.

Keywords: Arsenic, water, removal, adsorption, cast iron filings, steel wool, household filter

DOI: https://doi.org/10.15623/ijret.2013.0202021