Elimination of Cd (II) from Wastewater using Nickel (II) Tungstate Nanoparticles as Adsorbents: Adsorption Isotherm Study

Abstract

The removal of heavy metal ions from wastewaters, using efficient adsorbing nanoparticles, has been always an interesting area of research towards remediation of environmental pollutants. In this regard, toxic metal like cadmium (Cd) was preferred to be removed from selected wastewater samples using Nickel tungstate (NiWO₄) nanoparticles (NPs), acting as adsorbents. The NPs were synthesized using a facile sol-gel method and the calcinated sample was characterized using XRD, SEM-EDS and FTIR techniques. These results have displayed the formation of the NPs in wolframite structure. Using atomic absorption spectrophotometer (AAS), the adsorption capacity of the NPs was estimated using various supporting experimental factors like effect of NPs weight (20 mg L^-1), contact time (30 min), pH (5.0) and concentration of the metal ion solution (7 ppm). Further, Freundlich adsorption isotherm was applied on the results and it was noted that the rate of adsorption was in accordance with the empirical relation. The developed methodology has followed the Pseudo-first kinetics, indicating the efficacy of the method. All the results were compared with few standard scientific reports and it was observed that NPs were effective in removing the Cd(II) ions.