Evaluation of the Adsorption Capacity of the BiOX (X = Cl, I) and BiOX-GO Nanomaterials (NMs) for Water Treatment

Abstract

Water pollution is a global problem that severely impacts human and environmental health, water recycling, and the economy. In Mexico, due to water scarcity, potable water contains significant amounts of heavy metals (i.e., arsenic (As)); thus, there is a need for efficient and sustainable water treatment strategies. Bismuth oxyhalides, BiOX (X = Cl, Br, I), exhibit three-dimensional (3D) porous structures suitable for efficient adsorption activity. In addition, bismuth is an abundant and biocompatible element appropriate for fabricating sustainable environmental remediation technologies, such as adsorptive BiOX nanomaterials (NMs). In this study, we examine the adsorption capacity of BiOX (X = Cl, I), BiOX-GO (GO: graphene oxide) and GO NMs to remove methylene blue (MB), methyl orange (MO) and arsenite (AsO33−) from aqueous solution. BiOCl-GO 10%, BiOI, BiOI-GO 1%, BiOI-GO 10% and GO have an enhanced adsorption capacity, removing MB (20 ppm) within one hour using a low dose of NMs (1 mg/mL). In addition, BiOX-GO NMs can be easily separated from the solution and regenerated upon visible light activation due to the photocatalytic activity of the materials. The efficiency of the NMs under study for MO removal decreases, with the GO material having the highest efficiency (96%), followed by BiOX-GO 10% (78%). BiOCl-GO 1% removes arsenic from aqueous solution at low doses and short treatment times; 5 mg As/g adsorbent takes five hours; however, at longer adsorption times (24 h), BiOI-GO 1% excels in its arsenic removal capacity. Perlite-supported BiOCl NMs exhibit a weak capacity for water treatment due to the poor mechanical strength of perlite and the amount of surface-exposed BiOCl material. For the photocatalytic removal of arsenic (oxidation–adsorption), BiOI-GO 1% excels in arsenic removal with efficiencies > 70%.