ARSENIC WATER FILTRATION DEVICE, METHOD AND NANO METAL-OXIDES COATED RICE HUSK CHAR AS ADSORBENT MEDIUM THEREFOR

摘要

This invention reports a new process to develop a simple, low cost, portable domestic filtration device comprising: (a) a first layer of cleaned sand (b) a second layer of mixed metal-oxides (copper oxide, iron oxide) activated rice husk char nanocomposites, (c) a third layer of iron modified alumina, (d) a fourth layer of activated carbon and (e) a fifth layer of cleaned sand for removing arsenic from contaminated ground water and surface water. The novel nanocomposite materials used in the second layer contain hydroxyl groups (- OH) and metal-oxide nanoparticles which effectively remove both arsenic (III) and arsenic (V) to the desired permissible limit (=10 ppb) of drinking water. The use of iron modified alumina, activated carbon and sand in combination with nanocomposite materials enhances the overall performance of the filter. The filtration device can remove 2000 litre arsenic contaminated water with filtering rate of 5-7 litre/hr and works on the principle of adsorption and ion-exchange of arsenic on metal-oxides and with the hydroxyl (-OH) groups on the surface of activated rice husk char followed by filtration through the treated alumina, activated carbon and cleaned sand. The device also filters out other materials such as harmful bacteria, dissolved salts/solids (iron, fluoride) from contaminated water due to highly porosity in nature of the adsorbents with sufficient OH groups. Since low-cost raw materials, such as rice husk (agriculture waste), alumina, activated carbon, chloride salts of copper and iron are used for the removal of arsenic, the device becomes cheaper and affordable. (Fig. 1)