Adsorption of organic dyes using copper oxide nanoparticles: isotherm and kinetic studies

There are many methods to remove dyes from colored effluents to decrease their environmental impacts. Among the various methods, adsorption is a selective technology for dye removal. This research focuses on the adsorption of two cationic dyes, basic violet 16 (BV 16) and basic red 14 (BR 14), from textile effluent using copper oxide nanoparticles. The surface characteristics of copper oxide nanoparticles were investigated using scanning electron microscope (SEM) and X-ray diffraction spectroscopy. The effect of different variables such as adsorbent dosage, initial dye concentration, pH, and mineral salts was studied on the adsorption process. Langmuir, Freundlich, and Tempkin isotherms were assessed. The reaction kinetic was evaluated using pseudo-first, pseudo-second-order, and intra-particle diffusion kinetic models. It was found that BV 16 and BR 14 dyes removal increased by rising pH, contact time, and adsorbent dosage; whereas it decreased by addition of inorganic salts and increasing the dyes concentration. In addition, the results indicated that the data for adsorption of BV 16 and BR 14 onto copper oxide nanoparticles fitted well with the Langmuir isotherm. The rates of sorption were best fitted by the pseudo-second-order-kinetic. The research revealed that the copper oxide nanoparticles could be used as a suitable alternative for removal of dyes from colored aqueous solutions.