Removal of MC-RR by nano-zinc ferrite: investigation of adsorption behaviour, isotherms, kinetics, and mechanism

Given the high toxicity of microcystin-RR (MC-RR) and its persistence in drinking water systems, this study aims to provide a viable and efficient solution for its removal using zinc ferrite nanoparticles. Various experimental parameters influencing adsorption efficiency were examined, including initial MC-RR concentration, pH, adsorption time, and temperature. The surface charge properties of nano-ZnFe2O4 and MC-RR were investigated, and the electrostatic interactions during the adsorption process were analysed through the examination of various ion types and a comparison of Fourier-transform infrared (FTIR) spectra before and after adsorption. The adsorption performance of nano-ZnFe2O4 revealed that the adsorption kinetics and isotherms could be effectively described by the pseudo-second-order model and the Langmuir model, respectively. The empirical findings demonstrated that nano-ZnFe2O4 functioned as an effective adsorbent and achieved a maximum removal capacity of 1.28 mg/L for MC-RR at 273 K. The negative values of free energy (ΔG) and enthalpy change (ΔH) also confirmed that the process is both spontaneous and exothermic, which is favourable for adsorption.