Adsorption performance of tartrazine by CuxOy-ZnO composite synthesized via electrochemical method

In this study, a CuxOy/ZnO (CZO) composite was synthesized and evaluated for the adsorption of tartrazine (TA), a common azo dye in food and industrial applications.The effects of various parameters including pH, contact time, adsorbent dosage, and initial dye concentration were systematically investigated.The adsorption efficiency reached over 96% at pH 5 with 0.015g of CZO for 50mL of 100mg/L TA solution, while the maximum specific adsorption capacity exceeded 500mg/g at higher dye concentrations.Equilibrium was achieved after 90 minutes.Experimental data were fitted to four isotherm models, among which the Freundlich model gave the best correlation (R = 0.9802), with n = 3.68 indicating favorable multilayer adsorption on a heterogeneous surface.The Langmuir model also showed good agreement (qmax = 520.83mg/g,R = 0.9532), suggesting the presence of localized monolayer adsorption.Kinetic analysis revealed that the pseudo-second-order model provided the best fit (R = 0.9998), indicating that chemisorption played a dominant role.These findings highlight the potential application of CZO as an effective and low-cost adsorbent for dye removal from wastewater.