REMOVAL OF INORGANIC ARSENIC FROM WATER USING IRON(III)-LOADED ZEIN BASED ADSORBENT

Abstract

Zein protein, a by-product from agricultural industry, was modified with iron compound and prepared as adsorbent bead for the removal of inorganic arsenic in aqueous solution. The adsorbent was characterized by scanning electron microscope (SEM), x-ray fluorescence (XRF) and inductively coupled plasma-optical emission spectrometer (ICP-OES). The adsorbent was amorphous with non-porous surface and comprised mainly of carbon, nitrogen, oxygen and iron in proportion with the iron(III) chloride (FeCl3) loading amount. Various parameters for arsenic removal in batch system were studied at room temperature. The adsorption process was conducted under the optimized condition such as 0.7 mg/mL of iron(III) loading concentration in zein solution, pH 6 and contact time of 8 hr. or longer. The adsorption of arsenic(V) by this adsorbent was fitted to Langmuir isotherm model with the maximum capacity of 1.95 mg/g. Certain co-existing ions, especially those containing oxyanion structure i.e. phosphate, carbonate and sulphate, can significantly diminish the arsenic adsorption efficiency. This iron(III)-loaded zein adsorbent was applied to remove arsenic from waste water and drinking water with satisfactory result for relatively clean samples but less so far samples containing interference ions as mentioned previously.