Arsenic Removal Using Unconventional Material with Iron Content: Batch Adsorption and Column Study

Cosmin Vancea; Georgiana Mladin; Mihaela Ciopec; Adina Negrea; Narcis Duteanu; Petru Negrea; Giannin Mosoarca; Catalin Ianasi

doi:10.3390/toxics11100849

Arsenic Removal Using Unconventional Material with Iron Content: Batch Adsorption and Column Study

Toxics. 2023 Oct 10;11(10):849. doi: 10.3390/toxics11100849.

Authors

Cosmin Vancea¹, Georgiana Mladin¹, Mihaela Ciopec¹, Adina Negrea¹, Narcis Duteanu¹, Petru Negrea¹, Giannin Mosoarca¹, Catalin Ianasi²

Affiliations

¹ Faculty of Industrial Chemistry and Environmental Engineering, Politehnica University Timisoara, Bd. V. Parvan, No. 6, 300223 Timisoara, Romania.
² "Coriolan Drăgulescu" Institute of Chemistry, Bv. Mihai Viteazul, No. 24, 300223 Timisoara, Romania.

Abstract

The remediation of arsenic contamination in potable water is an important and urgent concern, necessitating immediate attention. With this objective in mind, the present study investigated arsenic removal from water using batch adsorption and fixed-bed column techniques. The material employed in this study was a waste product derived from the treatment of groundwater water for potable purposes, having a substantial iron composition. The material's properties were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier-transformed infrared spectroscopy (FT-IR). The point of zero charge (pH_PZC) was measured, and the pore size and specific surface area were determined using the BET method. Under static conditions, kinetic, thermodynamic, and equilibrium studies were carried out to explore the influencing factors on the adsorption process, namely the pH, contact time, temperature, and initial arsenic concentration in the solution. It was found that the adsorption process is spontaneous, endothermic, and of a physical nature. In the batch adsorption studies, the maximum removal percentage was 80.4% after 90 min, and in a dynamic regime in the fixed-bed column, the efficiency was 99.99% at a sludge:sand = 1:1 ratio for 380 min for a volume of water with arsenic of ~3000 mL. The kinetics of the adsorption process conformed to a pseudo-second-order model. In terms of the equilibrium studies, the Sips model yielded the most accurate representation of the data, revealing a maximum equilibrium capacity of 70.1 mg As(V)/g sludge. For the dynamic regime, the experimental data were fitted using the Bohart-Adams, Thomas, and Clark models, in order to establish the mechanism of the process. Additionally, desorption studies were conducted, serving as an essential step in validating the practical applicability of the adsorption process, specifically in relation to the reutilization of the adsorbent material.

Keywords: arsenic removal; batch absorption; fixed-bed column adsorption; mechanism of adsorption; unconventional material with iron content (UMIC).

Grants and funding

This research received no external funding.