Treatment of wastewater from a dairy plant by adsorption using synthesized copper oxide nanoparticles: kinetics and isotherms modeling optimization
Abstract Dairy plants produce 1 to 4 liters of wastewater per one liter of processed milk. The wastewater contains high values of COD and BOD concentrations, in addition to high levels of dissolved solids. In this study, synthesized copper oxide nanoparticles (CuONPs) coupled with Sophora Japonica fruit, were used as an adsorbent, for the first time, to treat the effluent of dairy plants in a batch adsorption process. The analysis techniques, FTIR, XRD and SEM were utilized to characterize the adsorbent. The COD removal, using (CuONPs)-based adsorbent, was investigated by varying contact time, masses of the adsorbent, initial COD value and temperatures. The optimum conditions for highest removal percentage were contact time of 120 minutes, a temperature of 25 °C, pH value of 7.5, and 1 g of adsorbent. The initial COD values used were in the range of 100–700 ppm. The COD percent removal was in the range of 77 to 95%. Freundlich isotherm exhibited the best fitting for the results (R2 = 0.998) with a favorable spontaneous exothermic adsorption process. Based on the calculated normalized deviation value, the modified diffusion model, intra-diffusion, and pseudo-second order kinetics all showed very good fitting for the adsorption data as indicated by the kinetics study.