Experimental Study On Removal Of Copper And Cadmium From Wastewater By The High Efficiency Adsorption Process

Copper and cadmium wastewater has strong toxicity and difficulty in treatment.If mishandled,it’s easy to cause water and soil pollution and threat to human health.In this paper,high efficiency adsorption process was developed,using thermal modified fly ash(TFA)as adsorbent to remove copper and cadmium in wastewater,and it created a lower effluent concentrationThe adsorption process of copper by TFA conformed to the pseudo-second-order kinetic model and Langmuir adsorption isotherm model.When the TFA dosage was 0.5 g/L and the reaction time was 20 min,the outlet copper concentration was 0.41 mg /L and the equilibrium adsorption capacity of TFA was 22.56 mg/g.The theoretical model of the high efficiency adsorption process was established in the single-component system and verified by experiment in the microfiltration cup.The measured values of the average produced copper concentration in the high efficiency adsorption process test with dilution factor(D)of 0.5 and 0.25 were respectively 0.2376 mg/L and 0.1894 mg/L.The theoretical values were 0.2259 mg/L and 0.1784 mg/L,with little difference between them.The lab-scale experiments of different TFA dosage showed that the copper concentration from the high efficiency adsorption process was low,and the concentration of effluent copper is proportional to D value.The copper concentration of effluent from the high efficiency adsorption process could remain stable and could reach the first class standard in the comprehensive discharge standard of sewage(GB 8978-2002).The concentration of suspended solids was closer to the calculated value and the membrane pollution was less by using the high efficiency adsorption technology.The adsorption process of cadmium by TFA conformed to the pseudo-second-order kinetic model and Langmuir adsorption isotherm model.According to the adsorption of copper and cadmium by TFA in the mixed wastewater,an efficient adsorption process model was established in the multi-component system.The model parameters were calculated by response surface method,and the effluent concentrations of copper and cadmium were calculated accurately.It was verified by experiment in the microfiltration cup.When the initial concentration was 1 mg/L,TFA dosage was 0.594 g/L and D value was 0.617,the measured average effluent concentration of copper and cadmium is 0.206mg/L and 0.230 mg/L respectively,which was less different from the theoretical value.The results of the lab-scale experiments showed that the average outgoing copper concentration in the efficient adsorption process test with dilution factor(D)of 0.5 and 0.25 were respectively 0.2376 mg/L and 0.1894 mg/L,and the concentration of cadmium were 0.319mg/L and 0.304 mg/L.These results were all lower than the conventional adsorption test.