Zinc curcumin oxide nanoparticles for enhanced adsorption of Congo red: kinetics and adsorption isotherms study

Abstract

In this study, zinc oxide nanoparticles, ZnO NPs, complexed to curcumin, were synthesized via a simple method to form Zn(Cur)O NPs. The prepared nanoparticles were characterized using XRD, TGA, and SEM. The choice of ZnO NPs is due to their physical and chemical properties. In addition, curcumin was used to enhance the activity of the nanoparticles. The effect of the adsorbent dosage (Zn(cur)O NPs), the concentration of the organic dye, and the pH were studied with variation in a specific range for each parameter. It was detected that the adsorption increases with increasing the amount of the nanoparticles and with decreasing the concentration of Congo red. By doing that, the numerous adsorption sites will be saturated. Furthermore, an acidic medium improves the adsorption process. The adsorption capacity qe was found to be 94.45 mg/g at pH = 2, which is better than in the literature. Hence, at pH equal 9 the adsorption occurred with a qe value of 70.86 mg/g. Moreover, it was found to follow a pseudo-second-order kinetic model fitting the Langmuir isotherm. © 2021 Elsevier Ltd