Highly Efficient Removal Of Typical Mine Pollutants（Molybdenum And Thallium） Using A Ti-Mn Binary Oxide As Adsorbent:Performance And Mechanism

Mineral resources is rich in China.Due to the predatory exploitation of mineral resources and environmental protection lagging behind economic development for a long time,mineral resources not only promote the development of national economy,but also bring a series of environmental pollution problems.Thallium and molybdenum are two typical cationic and anionic pollutants in mine sewage.Many environmental pollution events caused by excessive molybdenum and thallium have occurred in many areas at home and abroad,and their removal technology has attracted extensive research.Compared with traditional methods,adsorption method has attracted extensive attention because of its simple operation,low cost,high efficiency and recyclable adsorbent.However,there are few studies on the adsorption of anionic and cationic heavy metal pollutants in water at the same time.Based on the characteristics that titanium oxide has good adsorption performance for anionic heavy metal pollutants and the properties that manganese oxide can effectively adsorb cationic heavy metal pollutants in water,this paper is committed to prepare the Ti-Mn binary oxide,which can effectively remove anions and cations（molybdenum and thallium）from water.The ratio optimization and characterization of Ti-Mn binary oxide,molybdenum and thallium removal performance and mechanism were also studied.In this paper,a series of Ti-Mn binary oxide adsorbents were synthesized by a one-step simultaneous oxidation and coprecipitation method.The adsorbent with titanium manganese molar ratio of 2:1 was selected for systematic research.The adsorbent was characterized.The results showed that the material was nano irregular particles,with a specific surface area of 291.427 m~2/g and an average pore diameter of 5.49 nm.The adsorbent is composed of titanium oxide and manganese oxide,and the surface contains a large number of hydroxyl groups.The isoelectric point is about 4.72,which is between the isoelectric points of titanium oxide and manganese oxide.The results of the study on molybdenum removal performance and mechanism by Ti-Mn binary oxide are as follows.The maximum adsorption capacity of Ti-Mn binary oxide for molybdenum obtained in the experiment is 34.61 mg/g.The adsorption rate of Ti-Mn binary oxide to molybdenum is faster,and the Pseudo-second-order model is more suitable to describe the adsorption process.With the increase of p H,the adsorption capacity of Ti-Mn binary oxide to molybdenum decreases gradually.SO₄^2-、Si O₃^2-and PO₄^3-can inhibit the process of molybdenum,Ca²⁺can promote the adsorption process.The regeneration performance of the adsorbent is good.The adsorption mechanism of molybdenum by the material is that the molybdenum and the hydroxyl group on the surface of the adsorbent exchange ligands to form an internal coordination complex,thereby removing the molybdenum.The results of the study on thallium removal performance and mechanism by Ti-Mn binary oxide are as follows.Ti-Mn binary oxide can quickly and efficiently remove Tl（Ⅰ）from water,reaching more than 97%of the equilibrium adsorption capacity in 30 minutes,and the maximum adsorption capacity obtained in the experiment is 497.15 mg/g.With the increase of p H,the adsorption capacity of Ti-Mn binary oxide for Tl（Ⅰ）gradually increased.Ca²⁺,Cu²⁺and Zn²⁺inhibited the adsorption.The regeneration performance of Ti-Mn binary oxide after adsorption of thallium is good.The treatment of three simulated actual thallium water bodies by Ti-Mn binary oxide can quickly reach below the limit specified by the water quality standard within 10 minutes.The adsorption mechanism of titanium-manganese composite metal oxides for Tl（I）is that Tl（I）complexes with a large number of hydroxyl groups present on the surface of the adsorbent to form stable internal coordination complexes.