Removal of Arsenic in Groundwater Using Fe(III) Oxyhydroxide Coated Sand: A Case Study in Mekong Delta, Vietnam

Abstract

Because of its threat to the quality of freshwater resources and human health, arsenic (As) pollution is important to scientific communities and policymakers around the world. The Mekong Delta, Vietnam, is one hotspot of As pollution. Its risk assessment of different environmental components has been well documented; however, very few studies focus on As removal techniques. Considering this information gap, this study aimed to investigate the performance of an innovative and low-cost treatment system using Fe(III)-oxyhydroxide (FeOOH) coated sand to remove As(III) from aqueous solution. Batch and column experiments were conducted at a laboratory scale in order to study removal kinetics and efficiency. Experimental results indicated that the adsorption isotherm of As(III) on FeOOH coated sand using Langmuir and Freundlich models have high regression factors of 0.987 and 0.991, respectively. The batch adsorption experiment revealed that contact time was approximately 8 h for rough saturation (kinetic test). The concentration of As(III) in effluents at flow rates of 0.6 L/h, 0.9 L/h, and 1.8 L/h ranged from 1.1 µg/L to 1.7 µg/L. Results from this study indicated that FeOOH coated sand columns were effective in removing As(III) from water, with a removal efficiency of 99.1%. Ultimately, FeOOH coated sand filtration could be a potential treatment system to reduce As(III) in the domestic water supply in remote areas of the Vietnamese Mekong Delta.

In Situ Remediation of Arsenic-Contaminated Groundwater by Injecting an Iron Oxide Nanoparticle-Based Adsorption Barrier

“…At lower concentrations, the linear segment of Langmuir and Freundlich isotherms is more pronounced. Kim et al [48] performed batch adsorption experiments with concentrations similar to the present study (110 µg/L) and found good fits with linear and non-linear (Langmuir and Freundlich) isotherms models. Table 3 summarizes the estimated parameters for the adsorption of arsenic onto Goethite-coated sand columns.…”

“…The adsorption column was modeled using a linear system form of the advectiondispersion equation (ADE) [47]. A two-site model with first-order kinetics was used to explain the adsorption of arsenic in Goethite-coated sands following [34,48]. This model assumes an equilibrium state at a fraction (f ) of Goethite-coated sand, while nonequilibrium exists at the rest of the adsorption sites [49].…”

Tea-Waste-Mediated Magnetic Oxide Nanoparticles as a Potential Low-Cost Adsorbent for Phosphate (PO43−) Anion Remediation

“…However, in this study, it was indicated that adsorption of phosphate on TW-Fe 3 O 4 adsorbent is controlled by a pseudo-second-order reaction mechanism along with intra-particle diffusion. It is also noticeable from Figure 4d that the linear plot of intra-particle diffusion does not pass through the origin, which reveals that the mechanism of PO 4 3− adsorption on TW-Fe 3 O 4 is complex, and both the surface adsorption and intraparticle diffusion govern the rate-determining step [53].…”

Graphene Synthesis Techniques and Environmental Applications

“…Over the years, a number of techniques have been developed to treat and purify waste and groundwater. Some of these techniques include solvent extraction, flotation, precipitation, oxidation, evaporation, adsorption, and membrane filtration [ 167 , 168 , 169 ]. Because of its cost effectiveness, operational ease, low energy consumption, superior efficiency, and availability of a diverse range of membrane materials, membrane filtration is considered one of the leading techniques used for water treatments.…”