Preparation Of Manganese Oxide Composite And Its Adsorption Mechanism For Antimony In Water

China is currently the country with the richest antimony mineral resources in the world,and is also the world’s largest producer and exporter of antimony.Its output and export volume both account for about 80% of the world’s.The tin mine area of Lengshuijiang City,located in the Zijiang River Basin,Hunan Province,is known as the"antimony capital of the world".At present,the concentration of antimony in Loudi section of Zijiang River is 2.84 times higher than the limit value of drinking water sanitation standard（GB5749-2006）,and the pollution of antimony in tributaries is more serious,which affects the ecological environment health of the basin.Due to the existing conventional coagulation and adsorption treatment technology is difficult to achieve the effective removal of low concentration of trace heavy metal antimony in water,in this paper,a new manganese oxide composite material with low cost,easy to separate from raw water and can treat low concentration of antimony in water and make it reach the effluent standard was developed.The effects of Sb（V） concentration,temperature,p H,coexisting ions and other factors on the adsorption of antimony were discussed,and the adsorption characteristic curve was f itted;A continuous flow adsorption experimental device was designed to study the dynamic adsorption characteristics of the material;By means of SEM,TEM-EDX,BET,XRD,XPS and FTIR,the characteristics of the new manganese oxide composite material and its adsorption mechanism for trace Sb in water were analyzed.（1）A kind of manganese oxide composite material was synthesized by hydrothermal method.The main components are Mn₃O₄,Mn₂O₃,Mn OOH and MnO₂.The surface of the adsorbent is rough,with well-developed gaps and dendriform pores,and the structure of the adsorbent is mainly cluster layer;The valence states of Mn in the material are mainly+3 and+4,and the oxidation ability is strong.The surface hydroxylation of the material is obvious by XPS;Th e average pore size is 8.7 nm,which is characterized by amorphous structure.（2）When the initial concentration of Sb（V） is 0.5 mg/L and the dosage of manganese oxide composite is 5 g/L,the adsorption conditions are p H=7 and temperature is 15℃.After adsorption for 6 hours,the concentration of Sb in the effluent can reach the limit value of 5μg/L of the centralized surface water source in the environmental quality standard for surface water（GB 3838-2002）.After three times of desorption regeneration,83.4% Sb（V） can still be removed.（3）Both Langmuir equation and Freundlich equation can well reflect the adsorption process of low concentration Sb（V）in water,and the adsorption process is more in line with Langmuir equation.According to the fitting results,the maximum adsorption capacity of manganese oxide composite was 21.75 mg/g;The pseudo second order kinetic model can better reflect the whole process of adsorption reaction,which indicates that the physical adsorption is mainly carried out in t he initial stage of the reaction,and the chemical adsorption process involving different ion exchange and chemical bond breaking is the main reason for the adsorption of Sb（V） on the manganese oxide composite.（4）When the height of packing layer and influent concentration are adjusted,Thomas and Yoon-Nelson models can be used to describe the dynamic adsorption process of composite manganese oxides;When the height of packing layer is 10 cm,the influent flow rate is 6.5 m L/min,and the influent concentration is 3.6 mg/L,the bed penetration time is 60.2 h,and the Thomas fitting equation is C_t=³.6/（exp[0.03（19.83-Cot）]）;Yoon Nelson fitting equation is In（（C_t）/（3.6-C_t））=0.145t-5.1;According to the fitting results,the dynamic adsorption capacity of composite manganese oxide is about 18.69 mg/g,which provides theoretical reference data for actual production.