Enhanced As(III) and As(V) Adsorption From Aqueous Solution by a Clay Based Hybrid Sorbent

Rabelani Mudzielwana; Mugera Wilson Gitari; Patrick Ndungu

doi:10.3389/fchem.2019.00913

Enhanced As(III) and As(V) Adsorption From Aqueous Solution by a Clay Based Hybrid Sorbent

Front Chem. 2020 Jan 15:7:913. doi: 10.3389/fchem.2019.00913. eCollection 2019.

Authors

Rabelani Mudzielwana¹, Mugera Wilson Gitari¹, Patrick Ndungu²

Affiliations

¹ Environmental Remediation and Nano Science, Department of Ecology and Resource Management, University of Venda, Thohoyandou, South Africa.
² Department of Applied Chemistry, University of Johannesburg, Johannesburg, South Africa.

Abstract

In this study, a hybrid arsenic adsorbent was synthesized through intercalation inorganic and organic surfactant cations onto kaolin clay interlayers. The synthesized adsorbent was characterized X-ray fluorescence (XRF), Fourier Transform Infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET). Batch studies were conducted to determine As(III) and As(V) removal capacity of hybrid sorbent synthesized. It is found that As(III) removal is optimum at pH range of 4-6 while As(V) removal is optimum at pH range 4-8. The data for adsorption kinetics fitted to pseudo second order model implying that adsorption of As(III) and As(V) is chemisorption. The isotherm studies showed a better fit to Langmuir isotherm model indicating that adsorption of both As(III) and As(V) occurred on a mono-layered surface. The maximum adsorption As(III) and As(V) capacity at room temperature as determined by Langmuir model were found to be 7.99 and 7.32 mg/g, respectively. Thermodynamic parameters, ΔG° and ΔH° were found to be negative indicating that adsorption process occurred spontaneously and exothermic. Inorgano-organo modified kaolin clay was successfully regenerated for up 7 adsorption-regeneration cycles using 0.01 M HCl as regenerant. This study concluded that hybrid sorbent synthesized in this study is suitable for arsenic removal from groundwater.

Keywords: adsorption isotherms; adsorption kinetics; arsenic removal; clay based hybrid sorbent; thermodynamics.