Preparation Of Modified Red Mud And Research Of Photocatalytic Properties

Red mud is solid waste residue produced in alumina production process, at present,the annual output of red mud has reached about 30 million t, and its cumulative amount is about 200 million t, but its comprehensive utilization is less than 4% overall. Such a large number of red mud storage not only wastes the land resources, but also causes great harm to the environment. However, the Fe, A1, Si, Ti oxides contained in the red mud is the common catalysts, these catalysts can degrade the organic dye waste water by ultraviolet illumination, this method can full use of the red mud, and dispose the organic dye waste water, so the goal that governance the waste with the waste can be obtained.In this paper, the bayer process red mud was the research object by using methyl orange solution instead of dye waste water. The red mud was modified by using hydrochloric acid soaking method. Through the orthogonal experiment method, the optimal soaking conditions were confirmed : the hydrochloric acid concentration was 4mol/L, solid-liquid ratio was 1:3, soaking time was 1 h, soaking temperature was 70℃.At the same time, this paper also researched the effect of lighting time, light intensity,the initial pH value of methyl orange, the dosage of modified red mud, the storage time of modified red mud and the using cycles of modified red mud on the photocatalytic degradation of methyl orange solution, finally the result showed that: the best illumination time was 50 min, light intensity was optimal 15 cm for the distance of the high pressure mercury lamp and magnetic stirrer, the best initial pH value of methyl orange was 2.5, when the concentration of methyl orange solution was 50 mg/L, the optimum dosage of the modified red mud was 0.7 g/L, red mud can be stored for a long time and can be recycled many times.In addition,In this paper, by using analytical instrument, such as SEM and N2adsorption- stripping instrument, the microstructure, the specific surface area, the pore structure, the particle size and the chemical composition of the raw red mud and the modified red mud were analyzed. the raw red mud was mainly existed in the middle hole, and its specific surface area was relatively small, the quantity of middle hole in the modified red mud was more than the raw red mud, and its specific surface area increased to 317.14 m2/g, about 40 times compared with the raw red mud,the averageparticle size of the modified red mud was 29.0 nm, only about half of the average particle size of the raw red mud.