Adsorption of copper ions onto nano-scale zero-valent iron impregnated cashew nut shell

In this work, the synthesis and characterization of a new low-cost adsorbent such as nano-scale zero-valent iron impregnated cashew nut shell (NZVI-CNS) was studied for the removal of copper ions. The prepared adsorbent was characterized by Fourier Transform Infrared Spectroscop, Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy, Transmission Electron Microscopy, and X-ray diffraction. The adsorption parameters such as solution pH, adsorbent dose, initial copper ions concentration, contact time, and temperature were optimized. The adsorption kinetics of copper ions removal by NZVI-CNS have been studied by pseudo-first-order, pseudo-second-order, intraparticle diffusion, Boyd kinetic, and shrinking core models. The adsorption isotherms of copper ions removal by NZVI-CNS have been studied by Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models. The adsorption experimental data were best fitted with the pseudo-second-order and Freundlich models. The thermodynamic studies showed the adsorption process was spontaneous, feasible, and exothermic in nature. The results indicated that NZVI-CNS can act as an effective adsorbent for the removal of heavy metal ions from the water/wastewater by reducing its intake in the human food chain.