Preparation Of Pseudo-boehmite By Mild Liquid Phase Precipitation Method And Its Adsorption Performance For Roxarson

Pseudo-boehmite is widely used as adsorbent and catalyst carrier due to its high specific surface area,large pore volume,low density and many surface active sites.It is of great significance to prepare high-performance pseudo-boehmite by simple and low-cost methods.Liquid phase precipitation method is an important method for preparing pseudo-boehmite,which has the advantages of simple equipment,simple operation and wide source of raw materials.This paper focuses on the efficient and high-value utilization of sodium aluminate solution,the intermediate of bauxite dissolution,and the preparation of pseudo-boehmite with excellent organic arsenic adsorption performance from sodium aluminate solution by mild low-temperature liquid-phase precipitation method.The main research results are as follows:(1)The pseudo-boehmite with good adsorption performance for roxarsone(ROX)was successfully prepared by mild ethylene glycol(EG)assisted liquid phase precipitation method at 60-100℃.The effects of precipitation time,precipitation temperature and additive dosage on the physical and chemical properties such as phase,morphology and pore structure of the precipitate were studied.The results show that the appropriate amount of EG plays an important role in the formation of single-phase pseudo-boehmite.When the amount of EG is20-30 m L,the reaction system can quickly and stably precipitate single-phase pseudo-boehmite within 10-30 min,and no crystal transformation occurs within 12 h,but the particle size of the product increases slightly with the increase of precipitation time.In particular,the pseudo-boehmite prepared with EG addition of 25 m L,precipitation temperature of 60°C and precipitation time of 2 h had the best adsorption performance for ROX.The adsorption of ROX was in good agreement with the Langmuir isotherm model.The maximum equilibrium adsorption capacity calculated by this model was 189.71 mg/g.The excellent adsorption effect can be attributed to the high specific surface area(476.07 m~2/g)and abundant surface-active sites of pseudo-boehmite.(2)Furthermore,copper-doped pseudo-boehmite composites(H-Cu/PB and S-Cu/PB)were prepared by low-temperature one-step hydrothermal method and impregnation method under mild conditions using cheap copper chloride dihydrate as copper source.The adsorption of ROX on the doped composite material was in good agreement with the Langmuir isotherm model.The maximum equilibrium adsorption capacity of H-Cu/PB and S-Cu/PB for ROX calculated by this model was 301.91 and 199.88 mg/g,respectively,which was 59.14%and5.4%higher than that of undoped pseudo-boehmite.The enhanced adsorption performance of the composites can be attributed to the fact that the doping of copper improves the surface properties of pseudo-boehmite and increases the specific surface area of pseudo-boehmite(547.15 m~2/g).