Study On The Controllble Preparation And Adsorption Behaviour Of Magnesium Silicate With Multilevel Pore Structure

At present,with the development of society,a large number of heavy metal ions and dye pollutants are discharged into water bodies.Therefore,the efficient and safe treatment of wastewater has become a hot spot for global environmental protection.Among many water treatment methods,the adsorption has become the best method for treating water pollution,due to the advantages of uncomplicated operation and high economic efficiency.It is of great significance to design and construct green,efficient and low-cost adsorption materials for the treatment of pollutants in water.In this paper,the goal is to construct a high-efficiency magnesium silicate adsorption material with a multi-stage pore structure.A series of magnesium silicate with concentrated size distribution,large specific surface area and multistage pore structure were prepared by adjusting the ion concentration,the aging time of the precursor and the material ratio in the reaction system.Methylene blue,Congo red,and three heavy metal ions(Pb2+,Cu2+,and Cd2+)are used as probes,systematically studied the adsorption performance and adsorption mechanism of magnesium silicate.Exploring the structure-effective relationship between particle size,pore structure,and adsorption performance of magnesium silicate.The main research contents and results are as follows:(1)Based on the nucleation and growth control mechanism of nanomaterials,a rotating liquid membrane reactor-hydrothermal method was developed,a series of magnesium silicate adsorption materials with multi-stage pore structure and concentrated size distribution were prepared by using a rotating liquid membrane reactor.The results show that increasing the Mg2+concentration,the particle size is decreased,while the maximum adsorption capacity of magnesium silicate for methylene blue is gradually increasing;as the concentration continues to increase,the particle size is gradually increasing and the adsorption capacity is decreasing.The sample with the smallest particle size of 295.7 nm showed the largest adsorption capacity of 330.8 mg·g-1.(2)Based on the principle of in-situ phase transformation,the self-template method was developed.By adjusting the initial Mg2+ ion concentration of the reaction,a serious of basic magnesium carbonate precursors with different morphologies,which acting as the reaction template,are prepared.The magnesium silicate adsorption material with a multi-stage pore structure can be prepared under control by in-situ conversion.The results show that the maximum adsorption capacity of Pb2+,Cu2+and Cd2+of as-prepared sample is 1400.9,94.6 and 167.8 mg·g-1,respectively.Further research found that the increase of the aging time of the precursor is not conducive to the formation of magnesium silicate multi-level pore structure,and presents a negative impact on its adsorption performance.(3)Based on the reverse microemulsion method,by adjusting the ion concentration and the water content(W value)in the microemulsion system,a series of surface-modified microspherical magnesium silicate adsorption materials can be prepared.The research results show that the magnesium silicate material prepared by this method exhibition an excellent adsorption performance for Congo red solution.According to the Langmuir adsorption model,the best adsorption performance of the sample for Congo red is up to 917.43 mg·g-1,which maybe because the surface of magnesium silicate was modified by CTAB and exhibite electropositive,so it presents a higher adsorption capacity for Congo red due to electrostatic force.