Coprecipitation Preparation of Cu/Zn/Al-Hydrotalcite-Like Compound for Copper Removal from Electroplating Wastewater

Dekui Bai,Baixue Xia,Ni Wang,Dongxia Huo,Quanhong Ying,Xiaofang Wang

doi:10.1155/2019/5347920

Abstract

Cu/Zn/Al-hydrotalcite-like compound (Cu/Zn/Al-HTlc) was prepared by the coprecipitation method with ZnII, AlIII cations solution, and electroplating wastewater containing CuII cation. The preparation conditions of Cu/Zn/Al-HTlc were optimized. The metal ion pollutants removal effect and iodide maximum adsorption capacity of Cu/Zn/Al-HTlc were also studied. The physicochemical properties of the Cu/Zn/Al-HTlc were analyzed by X-ray diffraction, FTIR, SEM, N2 adsorption-desorption isotherms, and TG-DTG. The results showed that Cu/Zn/Al-HTlc should be prepared with the ZnII-AlIII molar ratio of 1.5 : 1, pH = 11, and aged at room temperature for 0.5 d. Structural analysis showed that the Cu/Zn/Al-HTlc was a layered compound. CuII and other metal ion pollutants can also be successfully removed from electroplating wastewater in the preparation process of Cu/Zn/Al-HTlc and reached Chinese National Emission Standard (GB 21900-2008). The optimal adsorption condition of calcinated Cu/Zn/Al-HTlc for iodide was as follows: the solid-liquid ratio was 1 : 250, the pH value was 8, and the adsorption process was carried out at 25°C for 30 min. The saturated adsorption capacity reached 1000 mg·g−1 at the optimal adsorption condition. The main reason for this high-saturated adsorption capacity of Cu/Zn/Al-HTlc was that iodide penetrated into the layered structure of Cu/Zn/Al-HTlc by physical adsorption and CuII undergoes a specific redox reaction, producing CuI. Hence, coprecipitation synthetic technology and prepared Cu/Zn/Al-HTlc could be potentially used for electroplating wastewater treatment.

Highlights

Heavy metal ions and organic substances are discharged by industrial activities, which could be consumed and accumulated in tissues of living organisms through the food chain [1,2,3,4,5]
Some heavy metal ions, such as copper, were necessary elements for human body, but excessive intake of CuII may bring about chronic copper poisoning [8, 9]. e Chinese National Electroplating Wastewater Discharge Standard (GB21900-2008) made clear regulations that CuII concentration must be less than 0.5 mg·L−1 [10]. erefore, the electroplating wastewater which can lead to health lesion must be properly treated and must be less than 0.5 mg·L−1 prior to discharge. ere are a lot of methods for heavy metal ions removal from electroplating wastewater [11], such as precipitation [12], ion exchange [13], membrane separation [14], trapping, and electrochemical reduction [15]
The coprecipitation product of electroplating wastewater and ZnII-AlIII showed a sharp diffraction peak at low angle 2θ, and its interplanar distance was 0.7514 nm, which was attributed to the typical HTlcstratified structure [27, 29]. e sharp and intense diffraction peak and corresponding interplanar distance were similar with standard Zn/Al-HT

Summary

Introduction

Heavy metal ions and organic substances are discharged by industrial activities, which could be consumed and accumulated in tissues of living organisms through the food chain [1,2,3,4,5]. Ere are a lot of methods for heavy metal ions removal from electroplating wastewater [11], such as precipitation [12], ion exchange [13], membrane separation [14], trapping, and electrochemical reduction [15] These methods need high cost and may produce the secondary pollution. Due to the layered structure, they have good adsorption property As adsorbents, they have been used to remove some metal ions and inorganic and organic anionic pollutants in recent years [23,24,25,26,27]. A rational preparation technology should be developed, the technology is essential to reduce heavy metal ions concentration of electroplating wastewater, and the product HTlcs could be applied to iodide pollutants adsorption. The preparation of Cu/Zn/Al-HTlc, optimum conditions, heavy metal ions removal capability, and iodide adsorption capacity were first reported

Experimental

Results and Discussion

Conclusions