The development of zinc-doped nickel ferrite nano-adsorbent for the adsorption of chromium (VI) from wastewater
Makhosazana Masuku, Jemal Fito Nure, Harrison Ifeanyichukwu Atagana, Ntuthuko W. Hlongwa, Thabo T.I. Nkambule
Abstract
The discharge of inappropriately treated chromium-containing wastewater from the textile and tannery industries is adversely affecting water quality and public health. Therefore, this study aimed to synthesize zinc-doped nickel ferrite (ZNF) nanoparticles as an adsorbent for chromium adsorption from wastewater systems. The adsorbent was characterized by SEM-EDX, XRD, FTIR, TGA, Raman, and BET. This material had a surface area of 78.41 m 2 /g, pore volume of 0.341cm 3 /g, and pore size of 14.9 nm. The removal of the chromium was investigated under the influence of the ZNF dose, pH of the solution, initial Cr concentration, and contact time. The maximum Cr(VI) removal was found to be 87.9 % at the experimental condition of an adsorbent dose of 0.25g/50 mL, contact time of 120 min, initial Cr concentration of 10mg/L, and solution pH 3 whereas the minimum removal of adsorption was recorded about 50 % which implies Cr adsorption was within the narrow ranges. This maximum Cr (VI) percentage was decreased from 87.9 to 70.4 % with increasing Cr (VI) concentrations from 10to 150 mg/L. Generally, adsorption performance increased with increasing adsorbent dose and contact time and decreased with initial concentration and pH. It was observed that this adsorption process was a monolayer as confirmed by the Langmuir isotherm model at R 2 0.99. and the rate of the adsorption was described by the second-order kinetics model at R 2 0.99. Furthermore, thermodynamic analyses showed that the adsorption process was spontaneous (ΔG from −6.83 to −7.52 KJ/mol), endothermic (ΔH 11.14 KJ/mol), and increase in degree of disorder (ΔS 22.95 J/molK). This entropy change indicated that the degree of randomness between the liquid-solid interface was increased. In conclusion, the adsorbent can be regenerated for up to five cycles but significantly decreases after three cycles. However, this technology still has a huge potential and is viable in industrial wastewater treatment. • Nanoparticle Zn 0.2 Ni 0.8 Fe 2 O 4 was successfully synthesized via coprecipitation synthesis • High removal of Cr (VI) was found to be 87.9% under specific experimental condition. • This adsorbent nanoparticle was found to be effective for reuse over up to 5 cycles • This nanoparticle was promised adsorbent for the remediation of industrial wastewater • Adsorption was spontaneous ΔG° -7.52 kJ/mol, endothermic (ΔH ° 11.14 KJ/mol), and increased randomness ΔS 22.95 J/molK