GREEN SYNTHESIS OF MANGANESE OXIDE NANOPARTICLES USING ANTHOCYANIN EXTRACT FOR THE SEQUESTRATION OF CRYSTAL VIOLET DYE

Abstract

Crystal Violet (CV) is a synthetic triphenylmethane dye that is widely used in biomedical staining, printing, and textile processing. Because of its great chemical stability, CV is a persistent pollutant in industrial effluent streams and is known to have hazardous and carcinogenic effects despite its usefulness. To address this concern, this study focuses on the Green Synthesis of Manganese oxide (MnATH-(O) NPs) utilizing anthocyanin (ATH) extract obtained from red cabbage, which serves as a stabilizing, capping, and reducing agent. The physiochemical properties of the green synthesized MnATH-(O) NPs were extensively analysed using multiple characterization techniques. Powder X-ray diffraction was employed to confirm the crystalline phase and estimate the average crystallite size, while Fourier Transform Infrared Spectroscopy (FTIR) was used to identify the surface functional groups involved in nanoparticle stabilization. The characterization results revealed that the synthesized material possessed a crystallite size of 20.3 nm, indicative of high crystallinity and phase purity. Additionally, the measured surface charge of −34.7 mV suggests strong electrostatic affinity toward positively charged azo dye molecules, supporting its potential as an efficient adsorbent in wastewater treatment applications. Batch adsorption experiments were conducted under varying conditions of initial dye concentration, contact time, adsorbent dosage and pH to optimize dye removal efficiency, attaining a removal efficiency of 98.36% within 60 minutes. The adsorption kinetics were best described by pseudo-second-order model demonstrating that the chemisorption was the predominant mechanism governing the interaction between MnO nanoparticles. Additionally, the equilibrium data fitted well with the Temkin isotherm model, suggesting multilayer adsorption on a heterogeneous surface. These findings highlight the potential of green-synthesised MnO nanoparticles as an environmentally friendly and highly effective adsorbent for the removal of cationic dyes. In addition to reducing environmental effect, using an eco-friendly synthesis process improves surface characteristics that are conducive to adsorption. Overall, this study shows a viable, affordable wastewater treatment method that might be scaled up and used in actual effluent systems.