Regulation Of Calcium Sulfate Crystal Synthesis By Carbohydrates And Exploration Of Its Arsenic Removal Performance

Calcium sulfate exists mainly in the form of or anhydrous gypsum in nature,and many industrial processes also produce large amounts of calcium sulfate.Although this inorganic mineral has been widely used in construction,rubber,coating,biomedicine and other industries,with the intensification of the contradiction between resources and environment,concerns are growing about how to improve the resources utilization,especially the level of high value utilization.The preliminary study shows that calcium sulfate is also a environmental purification material,but there are still some problems,such as low affinity to pollutants and unstable properties,which restrict its application in the field of environmental protection.Therefore,it is necessary to study the improvement of the adsorption properties of calcium sulfate and the application of functionalized modification from the optimization control direction of mineral crystal morphology and structure,which is of great practical significance to the full utilization of gypsum resources in China.This dissertation explores the hydrothermal method of sugar-molecule coupled Fe3+ ions to regulate the morphology of calcium sulfate.The effects of sugar concentration,Fe3+ concentration,reaction temperature,reaction time and other factors on the morphology of the modified product were investigated,and the mechanism of the effect of sugar molecules on the growth of calcium sulfate crystals was analyzed.The results showed that the concentration of sugar and Fe3+ ions in hydrothermal system had a significant effect on the morphology and structure of the product.Under the condition of 180 ? and the reaction time of 12 h,the synergistic effect of chitosan and Fe3+ ions can be used to obtain a novel spiny globular calcium sulphate with morphology and structure,and the coordination of glucose and Fe3+ ions can be used to obtain structured 3D bundle of calcium sulfate,and the synergistic action of sucrose and Fe3+ ions can be used to obtain tree like calcium sulfate.Combining XRD,FT-IR and other characterization reveals that the hydrolysis of Fe3+promotes the hydrolysis and aggregation of sugars,changes the molecular structure of sugars,and thus affects the nucleation and growth of calcium sulfate and changes the morphology of the product.The effect of chitosan modified calcium sulfate product on arsenic removal was investigated by intermittent adsorption experiment.The effects of pH value,reaction time,dosage of modified calcium sulfate and initial arsenic concentration on arsenic removal efficiency were discussed.At the same time,the kinetics of adsorption and isothermal adsorption curve were studied,and the mechanism of arsenic removal by modified calcium sulfate was preliminarily discussed.The results showed that the pH value of the solution was the key factor affecting the arsenic removal effect of calcium sulfate.The removal rate of arsenic increased with the increase of pH value of the solution.When the pH value is 11,the removal efficiency of 1 mg/L arsenic-containing water sample can reach 96.42%when the reaction is 12 h.The adsorption of arsenic by chitosan modified calcium sulfate is in good agreement with the Langmuir isothermal adsorption model.The adsorption of arsenic on modified anhydrous calcium sulfate may be uniform monolayer adsorption.The kinetic data of adsorption are more consistent with the quasi two stage kinetic model,and the adsorption process is mainly chemical adsorption.The research is of some reference value for the exploration of new structure of calcium sulfate inorganic functional materials and the exploration of their application potential.