Adsorptive removal of as (III) by aluminium Oxide/Hydroxide nanoparticles: Modelling of column studies

Abstract

The main aim of present work is to assess the applicability of aluminium oxide/hydroxide nanoparticles (AHNP) based low cost adsorbent synthesized through electrochemical route in column mode of operation. The adsorbent was found to be efficient and cost effective for the removal of highly toxic and carcinogenic metalloid (As (III)) from groundwater. The synthesized adsorbent was used for the treatment of simulated contaminated groundwater having As (III) concentration equivalent to that present in the groundwater of rural areas of Rajnandgaon District of Chhattisgarh state of India where the presence of As (III) along with several other contaminants have been reported. The nanoparticles were characterized with various sophisticated analytical techniques including XRD, FESEM - EDX and BET surface area analysis. The adsorption experiments show satisfactory results for simulated groundwater samples and the concentration of As (III) was brought down to below permissible limit of 10 μg/L (as per the USEPA standard). In the column mode of adsorption, the effects of bed height on the removal of As (III) in the influent was studied. Various models like Thomas model, Yoon-Nelson model and Adam-Bohart model were used to determine various constants related to maximum adsorption capacity of the adsorbent, time required for attaining 50% breakthrough curve (τ) and adsorption capacity coefficient. The Thomas model estimated the maximum adsorptive capacity of the AHNP adsorbent as 1309.8 µg/g for As (III) at the influent flowrate of 0.28 ml/min (with R2 value 0.93). The value of τ for AHNP adsorbent is found as 44153.5 min. Current studies indicate that groundwater contamination with As (III) can be managed by upscaling the AHNP as an efficient treatment solution.