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Removal of Arsenic (iii) Present in Ground Water of Bangladesh with Polymer Supported Hydrated Fe(iii) Oxides

Mohammad Arifur Rahman
Department of Chemistry, Dhaka University, Dhaka-1000, Bangladesh

Evanta Kabir
Department of Chemistry, Dhaka University, Dhaka-1000, Bangladesh

AM Shafiqul Alam
Department of Chemistry, Dhaka University, Dhaka-1000, Bangladesh

Abstract/ Executive Summary:

In the present study, a technique to remove arsenic has been developed with a polymer-supported hydrated Fe(III) oxide (HFO) by using a strongly basic anionic exchanger IRA-420 as the host material and FeCl₃-HCl-NaCl solution as the reaction environment. The optimized conditions were applied to a sample collected from Sonargaon, Dhaka. The removal efficiency of this method was more than 80%, which indicates that this method can be used as an efficient method for arsenic removal in Bangladesh. IRA-420-HFO exhibits more preferential adsorption of arsenic ions which is attributed to the Donnan membrane effect exerted by the host resin (IRA-420) as well as to the loaded HFO particles for specific interaction toward arsenic (III) ions. All the results indicated that HFO polymer derivative is an attractive adsorbent for efficient arsenic (III) removal from contaminated groundwater of Bangladesh.

Keywords: Arsenic; Adsorption; Removal; Anion exchanger; Hydrated Fe(III) oxide

Location: Department of Chemistry, Dhaka University, Dhaka-1000, Bangladesh

Start Date: 00-00-2015

End Date: 00-00-2015

Program Area: Crop-Soil-Water Management

Commodity: Water quality

Objectives:

1. To develop a hydrated Fe(III) hydroxide-loaded hybrid sorbent for efficient removal of arsenic from contaminated water. Arsenic removal by the new sorbent was evaluated by batch column experiments.

Methodology:

Chemicals and Reagents - All chemicals used in the study are of analytical grades. A basic porous anion exchange resin IR-420 (chloride form) cross-linked with divinylbezene was used in this experiment. De-ionized distilled water was used to prepare all solutions for this experiment. Standard As3+ ion solutions were prepared from As₂O₃ (Sigma Aldrich). All other chemicals were obtained from Sigma. Preparation of hydrated Fe(III) oxide sorbent - The anion exchanger dispersed with HFO particles, referred to as HFO derivative, was fabricated according to the method reported elsewhere. The procedure for the preparation of HFO consisted of the following four steps. First, 50.0 g (Cl^? form, strongly basic anion, 8% cross-linking, 0.30-1.20 mm particle size, 14-52 dry mesh, BDH, England) IRA-420 beads were soaked into 500 mL aqueous solution containing 40 g FeCl₃. Tetrachloroferrate anion (FeCl4^?) is readily formed in a ferric chloride solution in presence of an excess amount of hydrochloric acid or chloride. Tetrachloroferrate anion is relatively large in size and relatively weak hydrated anion15. FeCl4^? is preferably loaded onto IRA-420 resin beads in aqueous solution in the presence of chloride ion16. Moreover, as the precursor of HFO, FeCl4^? is decomposed in dilute NaOH solution or neutral solution. Then, Fe(III)-IRA-420 beads were filtered, vacuum desiccated, transferred to a NaOH-NaCl solution (each at 7% w/v concentration), and then stirred for 24 hours. Fe(III) pre-loaded on IRA-420 was then precipitated as Fe(III) hydroxides in the inner surface of IRA-420. The resulting particles were rinsed with deionized water until the conductivity of the filtrate was close to that of the deionized water, followed by rinsing with 80:20 (v/v) ethanol-water solutions. Finally, the solid particles were thermally treated at 55 °C for 6 h and then vacuum desiccated to yield HFO spheres.

Source of Information: Dhaka Univ. J. Sci. 63(2):85-89, 2015 (July); ISSN 1022-2502 (Print) 2408-8528 (Online);

Article Link (Online Journal): DOI: http://dx.doi.org/10.3329/dujs.v63i2.24441

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

In the present study hydrous Fe (III) oxide (HFO) was successfully loaded on an anionic exchanger to obtained a hybrid adsorbent HFO for the removal of arsenic (III) from contaminated water. HFO showed effective adsorption capacity of arsenic(III) from contaminated groundwater. Column experiments showed that arsenic(III) adsorption on HFO could result in a concentration below 50 μg/L, which was the maximum concentration limit set by WHO (World Health Organization) for Bangladesh. The removal efficiency is more than 80%, therefore, HFO polymer derivative may be considered a suitable adsorbent for efficient arsenic(III) removal from contaminated groundwater.

Knowledge Management: Journal, Online Circulation