New Bionanomaterial for the Efficient Adsorption and Removal of Malachite Green from Water and Wastewater

Abstract

In this work, a new bionanosorbent of graphene oxide (GO) and Dunaliella salina (DS) microalgae was synthesized and applied for the adsorption and removal of malachite green (MG) from water and wastewater samples. The bionanosorbent (GO@DS) ​​was characterized by Fourier transform infrared spectroscopy, zero charge point, scanning electron microscopy coupled to an energy dispersive X-ray detector, and X-ray diffraction. Using multivariate optimization and response surface methodology, the optimal adsorption variables were pH = 5, GO@DS ​​mass = 5 mg, and malachite green concentration = 75 mg L−1, for which an adsorption capacity of 232.77 mg g−1 was obtained. Experimental kinetic results were adequately fit to the Elovich model. The Langmuir equilibrium model satisfactorily described the data obtained and a maximum adsorption capacity of 160.8 mg g−1 was obtained. The adsorption process was thermodynamically favorable, spontaneous, and exothermic. Finally, the GO@DS ​​was applied to remove the dye from natural water and effluents, obtaining MG removal values ​​between 85 and 99%, demonstrating the efficiency of the bionanosorbent in real and complex matrices.