Efficient Removal of Pb²⁺, Cd²⁺, and Hg²⁺ from Wastewater Using Advanced Graphene Oxide-Zirconium Hybrid Composite

Abstract

The contamination of water by heavy metals poses a significant threat to both the environment and public health, and hence, the effective purification of contaminated water remains a formidable challenge. Recently, graphene oxide (GO) has shown significant potential for removing heavy metals due to its large surface area, availability of functional groups, and high adsorption affinity. However, it is associated with several disadvantages such as aggregation, reduced surface area, and pH sensitivity. To overcome such drawbacks, the surface of GO has been modified with zirconium and amino trimethylene phosphonic acid (ATMP), forming the GO-ZrATMP composite. The newly synthesized hybrid GO-ZrATMP composite has been well characterized by several characterization techniques such as Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM), etc. This composite has been employed for the adsorption of Pb2+, Cd2+, and Hg2+ from aqueous solution. Adsorption isotherm and kinetics results showed that the adsorption of Pb2+, Cd2+, and Hg2+ on GO-ZrATMP was a monolayer adsorption process and dominated by physisorption and intraparticle diffusion. Thermodynamic studies revealed that the sorption process is endothermic, spontaneous, and feasible. The maximum adsorption capacity was found to be 373, 320, and 281 mg/g for Pb2+, Cd2+, and Hg2+, respectively. Further, a study pertaining to distribution studies (in aqueous and various electrolyte media) and metal separations has been conducted. Based on these studies, efficient binary and ternary metal separations have been achieved using GO-ZrATMP composite material. The present study clearly demonstrates the potential of GO-ZrATMP composite in eliminating heavy metals from both water and real wastewater.