Development of simple and cost effective method for arsenic (III) removal

Abstract

In the present study, eight locally available low cost adsorbents (raw and heat treated) have been screening for its capability to remove As(III). The shale sedimentary rock (SSR) was selected as a good adsorbent based on high As(III) removal. The activation of adsorbent was carried out by heat (250 - 550°C) and acid treatment (0.1 - 1 M H2SO4) in order to chose the best treatment method for As(III) removal. Sorption experiments were conducted to examine the effect of initial As(III) concentration, contact time and initial pH on As(III) removal by SSR. Results show that, only by heating the adsorbent at 500°C for 1h, 0.2 g of SSR adsorbent capable to reduce the residual As(III) concentration below than maximum concentration limit (10μg/L)for initial concentration from 100 to 700 μg/L and optimum pH ranges between 3 to 9 after 24 h of contact time.The adsorption data fits well with Langmuir isotherm and yielded Langmuir mono layer capacity of 0.987 mgAs(III)/g of SSR at pH 7. The SSR adsorbent has been successfully used for the removal of arsenic from seven real groundwater samples containing arsenic in the range of 20.2 to 697.34 μg/L with 86.73 to 97.86% removal efficiency.