Effectiveness of Artificially Synthesized Granitic Residual Soil-Supported Nano Zero-Valent Iron (Gr-nZVI) as Effective Heavy Metal Contaminant Adsorbent

Abstract

Supported nano zero-valent iron is receiving great attention nowadays due to its effectiveness in treating heavy metal pollutants. Therefore, this study aimed to investigate the effectiveness of granitic residual soil-supported nano zero-valent iron (Gr-nZVI) for the removal of the heavy metals Pb2+, Cu2+, Co2+, Cd2+ Ni2+ and Zn2+ in mixture solutions under different experimental conditions of batch equilibrium tests. In this study, Gr-nZVI was successfully synthesized by using the chemical reduction of Ferric Chloride Hexahydrate (FeCl3.6H2O) and Sodium Borohydride (NaBH4). The physical and chemical properties, morphology and mineralogy of all adsorbents were characterized by the Braeuer–Emmett–Teller (BET) method, cation exchange capacity (CEC), X-ray fluorescence (XRF), scanning electron microscopy (SEM), field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Isotherm, kinetic and diffusion model analyses were conducted to fit the experimental data. The results show rapid adsorption within 5 min in the initial adsorption stage for Pb2+ on nZVI (qe.Pb = 17.89 mg/g) and Gr-nZVI (qe.Pb = 15.29 mg/g). nZVI and Gr-nZVI also showed no significant effects on pH and temperature, serving as a good example of an energy-efficient process. The isotherm data fitted better to the Langmuir model and the pseudo-second-order kinetic model for the adsorption of all of the heavy metals. The diffusion models revealed that adsorption was not the only rate-limiting step. In this study, nZVI compared to Gr-nZVI and Gr demonstrated superior adsorption capacity for the heavy metal adsorption selectivity. Hence, these materials can be utilized as alternative energy-efficient adsorbents for the adsorption of metal ions from wastewater.

Attapulgite-Supported Nanoscale Zero-Valent Iron Composite Materials for the Enhanced Removal of Ni2+ from Aqueous Solutions: Characterization, Kinetics, and Mechanism

“…The results indicated that the surface diffusion process could remove Ni 2+ faster in the early stage of the reaction. As the reaction proceeded, the reaction rate was limited to a certain extent due to the high resistance of the boundary layer, which led to the slowing down of the reaction rate and eventually to the equilibrium [34]. The fitted plots showed that none of the fitted straight lines passed through the origin, indicating that the adsorption rate of Ni 2+ by nZVI@ATP was limited by other factors such as surface diffusion and surface adsorption in addition to the main intra-particle diffusion.…”

Use of Zero-Valent Iron Nanoparticles (nZVIs) from Environmentally Friendly Synthesis for the Removal of Dyes from Water—A Review

“…Hydrophobic supports also extend the reactivity of nanoparticles and enable the adsorption of hydrophobic contaminants like PCBs onto the nZVI surface. Materials such as phyllosilicate minerals [225], granitic residual [226], silica [227], activated carbon [228], zeolites [229], biochar [230] or polymer membranes have been utilized as supports for nZVIs. Immobilization of nZVIs on these supports can be achieved through carboxyl, hydroxyl, or amine groups serving as chelating sites.…”