A Sustainable Approach for Enhancing Cationic Dyes Adsorption in Single and Multiple Systems using Novel Nano Ferrites Modified with Walnut Shell.

Walnut shell has been used in various experimental studies for different dyes removal, but it is exciting to study the adsorption behaviour of bio‐waste (walnut shell) in combination with spinel zinc ferrite which resulted in the formation of a novel material having magnetic properties and help in easy separation after the wastewater treatment. Novel magnetic walnut shell zinc ferrite (WSZF) composite has been synthesized and used to remove Malachite Green and Methylene Blue from aqueous solution in single and binary dye systems. Different techniques have been used to characterize the composite such as Fourier Transform Infrared Spectroscopy, X‐Ray Diffraction, Field Emission Scanning Electron Microscopy, Energy Dispersive Spectroscopy, Thermogravimetric Analysis and pHzpc. Adsorption of dyes were studied to see the effect of time, pH, adsorbent dose, dye concentration and temperature. The Lagergren pseudo second order model fitted well among various kinetic models employed. Langmuir adsorption isotherm best fitted with maximum adsorption capacities of 86.20 and 169.5 mg/g in single dye and 23.92 and 18 mg/g respectively in binary dye system for Malachite Green and Methylene Blue. Process was spontaneous and ΔH° were found positive, confirmed endothermic process of adsorption. The composite's regeneration capacity was studied for five cycles and at the end of five cycle the efficiency of the material was found to be around 80 % for both single as well as binary dye systems. It is concluded that the chosen WSZF will be the optimum solution for cationic dyes removal. [ABSTRACT FROM AUTHOR]