Regulation Of The Modified Silicon Source In The Preparation Process Of NaP Zeolite

In this paper,the prepared ethyl orthosilicate?TEOS?silicon gel is used as the silicon source.The feasibility of controlling the modification degree of silicon source and synthesizing controlled pore size and particle size of high-silicon Na P zeolite was explored.Moreover,the influence factors in the process of preparing silicon source on Na P zeolite were studied.?1?For the modification of silicon source,the molar ratio of the material is n?Si O₂?:n?Al₂O₃?:n?Na₂O?:n?H₂O?=1.00:0.22:0.65:100.00 system,the growth process of hydrothermally synthesized Na P zeolite conforms to the solid-phase conversion mechanism.?2?The microcrystalline structure evolution of Na P zeolite is closely related to the silicon source precursor:alkali treatment of TEOS results in mesoporous chain/cyclic silicon,which is beneficial to increase the micropore porosity of Na P zeolite and reduce the average particle size of Na P zeolite.The adsorption rate of Cu²⁺with the concentration of 50 mg/L by Na P-OH^-zeolite reaches 83.3%.Acid treatment of TEOS produces three-dimensional network silicon,which is beneficial to produce Na P zeolite with large pore size,particle size and skeleton silicon.For only 20minutes,the adsorption rate of methylene blue with the concentration of 50 mg/L by Na P-H⁺reaches more than 98%.?3?The degree of TEOS hydrolysis polymerization affects the physical and chemical properties of Na P zeolite.The enlargement of n?H₂O?/n?Si O₂?leads to that the particle size of Na P zeolite firstly increases and then decreases.Excessive ethanol leads to the generation of heterocrystals and reduces the purity of Na P zeolite.When the TEOS hydrolysis time was extended from 1 h to 24 h,the particle size,specific surface areas and pore size of Na P zeolite gradually increased.Ethanol plays a dual role in narrowing the crystal spacing and inhibiting particle growth during the formation of zeolite.The optimal acid hydrolysis conditions of TEOS:the p H value of1.0,the n?H₂O?/n?Si O₂?of 12 and the n?Et OH?/n?Si O₂?of 2,hydrolyzation by HCl for24 h.?4?The adsorption experimental of methylene blue B by Na P-HCl zeolite conforms to the quasi-second order kinetic equation and Langmuir adsorption isotherm.By adjusting the acid hydrolysis time,water content and ethanol content of HCl pretreatment TEOS process,the maximum adsorption capacity of methylene blue by Na P zeolite increased from 40.24 mg/g to 76.33 mg/g.