Preparation and Characterization of Ferrihydrite: Application in Arsenic Removal from Aqueous Solutions

Abstract

Arsenic pollution is a public health hazard in Burkina Faso due to its impact on human health and water resources. To mitigate this pollution, ferrihydrite material has been synthesized and characterized to be used as adsorbent for arsenic removal in aqueous solutions. This study aimed to contribute to improve of access to clean drinking water by removing arsenic from water using ferrihydrite. Arsenic species such as As(III) and As(V) were removed through batch adsorption. Experiments were carried out in batch mode using arsenic aqueous solutions. The characterization of ferrihydrite using Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDX), X-ray Diffraction (XRD), Infrared (IR), and Brunauer Emmett Teller (BET) showed that an amorphous and microporous 2-line ferrihydrite. The total specific surface area and pH at point of zero charge (pHpzc) were 184.518 m²/g and 9.41, respectively. The optimal adsorbent doses were 4 g/L for As (V) and 8 g/L for As (III). The optimum pH range for the adsorption of As (V) and As (III) was between 2 and 10, The maximum adsorption capacity was 15.07 mg/g for As(V) and 13.01 mg/g for As(III) with increasing concentration between 2 and 16 mg/L. Equilibrium time for As (V) and  As (III) on ferrihydrite was found to be 720 min and 960 min, respectively. The adsorption of As(V) and As(III) was consistent with the Langmuir monolayer model on ferrihydrite. Arsenic adsorption was occurred according to spontaneous chemical reaction. Arsenic removal was occurred on a monolayer following the pseudo-second order kinetic.