Green ferrites nanoparticles synthesis using Aloe vera and watermelon rinds: their applications as sorbents in the purification of direct golden yellow RL dye wastewater.

The sorbents Ni-Cu-FNP's, Ni-Zn-FNP's, Mn-FNP's, and Zn-FNP's were synthesised and utilised for the removal of Direct Golden Yellow RL dye. The optimum pH for the adsorption of direct golden yellow RL dye was 4, and 3 having the sorption capacities of 32.56, 30.44, 34.39, and 36.91 mgg⁻¹ for Ni-Cu-FNP's, Ni-Zn-FNP's at 45 min and Mn-FNP's, Zn-FNP's at 60 min respectively with the optimum dosage of 0.05 g/50 mL. The maximum sorption capacities were 39.08 (Ni-Cu-FNP's), 35.08 (Ni-Zn-FNP's), 42.93 (Mn-FNP's), and 44.22 mg/g (Zn-FNP's) at 40°C, 37°C, 44°C, and 44°C respectively and the reduction observed in the sorption capacity by raising the temperature, showed that the process is exothermic The optimal initial concentration of dyes for all the sorbents having the maximum sorption capacities of 54.30 mg/g (Ni-Cu-FNP's), 51.25 mg/g (Ni-Zn-FNP's), 63.45 mg/g (Mn-FNP's), and 66.35 mg/g (Zn-FNP's) were 75, 100, 100, and 75 mg/L respectively to get maximal acidic dyes adsorption. Langmuir equilibrium isotherm for sorption showed good fitness on the data obtained by sorption while the pseudo-2^nd-order proved good fitness on kinetic data of experiments. Surfactants, detergents, and different molar solutions of electrolytes (NaCl and AlCl₃) decreased the sorption capabilities of the sorbents for the selected dye. [ABSTRACT FROM AUTHOR]