Synthesis Of Fe/Al Bimetallic Material And Application For Environmental Remediation

Zero-valent iron is widely used in water pollution treatment.There are lots of studies have shown that ZVI has a good effect on heavy metal removal and organic degradation.However,ZVI has the disadvantages of agglomeration and oxidation.Therefore,modified remediation materials based on ZVI are the hotspot of water pollution treatment.In this paper,Fe/Al bimetallic material was used as the remediation materials.Cr(Ⅵ),diclofenac and carbon tetrachloride were target pollutants.Through experiments,removal efficiency and reaction mechanism of target pollutants were obtained.The main results of this study are as follows:(1)Compared with pure zero-valent iron,Fe/Al bimetallic materials can provide more reactive sites,and the removal efficiency of Cr(Ⅵ)in water can be better,which can reach more than 90%.The removal rate is 4.44 times than ZVI under the same conditions.Fe/Al bimetallic particles have a wider range of pH application.The kinetics analysis of reaction showed that the removal of Cr(Ⅵ)by the material accords with the pseudo first-order kinetics model.Furthermore,the material characterization results after reaction indicate that galvanic cell effect,zero-valent metal reducibility,and Fe(Ⅲ)-Cr(Ⅲ)mixed hydroxyl precipitation process are the main surface reaction mechanisms for Cr(Ⅵ)removal.(2)The Fe/Al bimetallic material can be used to degrade diclofenac in water.Ultrasound condition can improve the removal rate of diclofenac,removal rate of diclofenac was 88%and the highest reaction rate was 1.88 mg·L-1·1 min-1 when the reaction time was 1 h.But,when bimetallic material was used alone,removal rate of diclofenac was 75%and the maximum reaction rate was 1.98 mg·L-1·min-1.When the ultrasound and the material were synergistic,the pH of solution after reaction was maintained at 4.0.Cavitation,Fenton,and Fenton-like reactions are the main mechanisms for diclofenac removal.(3)Calcium alginate gel-coated Fe/Al bimetallic microsphere material has a good removal effect on carbon tetrachloride in water.Under the optimal experimental parameters,the removal rate of carbon tetrachloride can exceed 60%when the reaction time exceeded 1h.After 4 h,the dechlorination efficiency became stable and maintained at the 80%.At the first hour,the reaction rate reached a maximum of 2.49 mg/L h.The pH had a significant effect on calcium alginate gel shell,and bimetallic material had the best removal rate on carbon tetrachloride when pH was 7.The pH of the system was basically maintained at 6.8.