Arsenic and fluoride adsorption from multielement solutions onto aluminium modified montmorillonite

Abstract

Groundwater is the primary source of drinking water worldwide. However, it might be harmful to consumer's health due to the presence of trace elements, such as arsenic and fluoride, commonly found in Latin American. The main objective of this study was to investigate the adsorption parameters of arsenic (As) and fluoride (F) dissolved in multielemental solutions containing vanadium (V) and boron (B), on aluminium-modified montmorillonite. To achieve that, a new adsorbent was synthesised and characterised using X-ray diffraction spectroscopy (XRD), Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-Ray (EDX) and N2 adsorption/desorption isotherm techniques. Adsorption efficiencies for As and F were evaluated in multielement solutions considering the simultaneous occurrence of B and V, naturally present in groundwater. Kinetic and equilibrium adsorption experiments were carried out in batch conditions for both, mono and multicomponent solutions. The adsorbent characterization indicated an effective incorporation of Aluminium (Al) into the aluminosilicate layers and at the external surface of the montmorillonite. The adsorption process for multielement solutions took a short time and the As adsorption was not affected by the presence of V, B, or F in the solution while F adsorption parameters were enhanced by the co-occurrence of the other species in the solution. The maximum adsorption capacities were 21 and 68 mg g−1 for As and F, respectively, in the presence of B and V, at low adsorbent dosage. The new material was also tested for groundwater samples collected from Buenos Aires province (Argentina) that were naturally contaminated with As, V, B, and F. The removal of these elements was lower when compared to synthetic solutions. However, the material's efficiency in removing the ions from natural groundwater was approximately 50%. These results suggest that the material could be used to develop filters to remediate arsenic and fluoride from naturally contaminated groundwater.