Zinc oxide nanoparticles for removal of arsenic from water

Abstract

Removal of arsenate, As(V) from water was achieved using zinc oxide nanoparticles. The nanoparticles were synthesised from zinc acetate dihydrate and sodium hydroxide (NaOH) using the wet chemical sol-gel method. Different synthesis parameters were explored; including different ratios of Zn:NaOH and calcination temperatures. The synthesised samples were subsequently characterised and tested to investigate the adsorption capabilities of ZnO towards As(V). The colourimetric approach was utilised to analyse the samples’ performance. The particles had a relatively large average size as tested by the nanoparticle size analyser and the X-Ray Diffraction (XRD) characterisation of the samples confirmed the formation of ZnO. The peaks were narrow with high intensity, which indicates a larger crystal size and stable crystallinity. The samples showed a linear trend of increased adsorption capacity with the contact time. However, as indicated by the XRD and nanoparticle size analyser results, the particles had agglomerated and this has caused the total surface area to shrink. In summary, ZnO nanoparticles were successfully synthesised and were successful in adsorbing As(V) with different percentages for each sample. The adsorption trend was clear with respect to the changing parameters.