Nature Environment and Pollution Technology (Dec 2020)
Kinetic and Adsorption Study for Removal of Arsenic from Aqueous Medium by Low Cost Bentonite of Rajmahal Hills and Hazaribagh, Jharkhand
Abstract
The paper deals with the feasibility of arsenite removal by the adsorption from bentonite mineral. Groundwater arsenic contamination has been reported in different parts of the world including Jharkhand, Bihar and Uttar Pradesh. Tube wells in Holocene Newer Alluvium are characterized by grey to black coloured organic-rich argillaceous sediments which have arsenic-contaminated groundwater. The majority of arsenic present in the groundwater is in the form of As(III) which exists as uncharged species arsenic tri hydroxide at pH value of less than 9.2. Arsenite is removed by various techniques like coagulation microfiltration, fixed bed adsorption, bioremoval, ion exchange, membrane filtration, etc. Our studies have shown that locally available bentonites containing a unit of montmorillonites can remove the arsenic from an aqueous medium. On the treatment of 100 mL arsenite solution with 300 mesh sieves bentonites up to different intervals of time, it has been found that bentonites are good adsorbent of arsenite. The percentage removal of arsenite is up to 99 per cent with 3 g sodium derivative of bentonite for 1 hour. The removal efficiency, adsorption isotherm and kinetic studies show the suitability of bentonite minerals for arsenic removal following first-order kinetics. Freundlich and Langmuir isotherms are obeyed in the adsorption of arsenite by bentonite minerals. Adsorption of arsenic by bentonite minerals has proved to be a low-cost eco-friendly method. Sodium derivative of bentonite minerals has been found more efficient for removal of arsenite.
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