Crystallization Regulation Of Transition Metal Doped NaP Zeolite And Its Adsorption Properties

The GIS structure skeleton and alkali characteristics of NaP zeolite determine its well metal ion exchange capacity and adsorption ability.It can be widely used in gas adsorption in the industrial production,heavy metals,radioactive material removal,etc.NaP zeolite has very good desorption of Ca2 + and Mg²⁺,and it can extract K+ from sea water soft water quality,also can adsorb other ions,phenol and other organic matter in sewage in the process of water purification.It has enormous potential in adsorption of hard water treatment.Meanwhile,the NaP zeolite has higher adsorption capacity of non-ionic surfactant and the stable performance for some relatively expensive formula in detergent.It is considered be the most promising alternative detergent product.In this paper,sodium silicate and sodium mutilate were used as source of silicon and aluminum source,respectively.And the acid alkalinity was adjusted by sodium hydroxide.NaP zeolite was prepared by hydrothermal synthesis method.The effects of different crystallization temperature and crystallization time on the preparation of NaP zeolite were investigated,and the kinetics parameters were calculated by the optimum conditions.The space hindrance agent was added to regulate the zeolite synthesis process.The influence of the type of steric hindrance agent and the amount of addition was investigated.Meanwhile,the mechanism of regulation was briefly explored.Doping metal was a method to improve the performance of NaP zeolite,the optimal metal and doping amount was selected,and the substitution process of doping metal was preliminarily explained.The performance of synthetic NaP zeolite was evaluated by using Zn²⁺ ion adsorption removal ratio.The results are as follow:?1?The activation energy Ea and the pre-exponential factor A of the crystallization process of NaP zeolite were obtained based on the XRD analysis and the Avarami-Erofeev model fitting calculation.The crystal growth rate constant and apparent crystallization rate constant were basically consistent with the increase of temperature.?2?The addition of steric hindrance in the preparation of NaP zeolite can effectively reduce the grain size of NaP zeolite and obtain small size NaP molecular sieve.The order of control ability of nonionic steric agents to molecular sieve growth process was: ring chain,short straight chain,long straight chain.The regulation ability of ionic steric agents was related to the type and concentration of ions.Cationic steric hindrance was beneficial to inhibit the formation of hetero crystal.?3?The NaP zeolite was synthesized with cyclohexanol as steric hindrance agent?n?Al₂O₃?/n?cyclohexanol?=1:3?,the specific surface area increased from 26.76 m2/g to 82.08 m2/g,and the NaP zeolite was single grain decentralized state crystalline,in which the ratio of pore diameter around 2 nm is maximized,which up to 37.44%.At the same time,NaP zeolite prepared by cyclohexanol as steric hindrance has good adsorption effect on Zn²⁺ in sewage.When the ambient temperature reaches 25 oC,the adsorption time is 30 min,and the removal rate of Zn²⁺ can reach 98%.?4?A series of doped Fe/NaP,Co/NaP,Ni/NaP,Ti/NaP zeolite were prepared by hydrothermal synthesis.The introduction of metal heteroatoms resulted in larger crystallites of the zeolite.The maximum unit cell volume of the Co/NaP zeolite reached 1013.54 ?3,which was slightly larger than the volume of the NaP zeolite unit cells in the standard database of 1006.8 ?3.The surface area of Co/NaP reached 162.4896 m2/g.The Zn²⁺ adsorption evaluation showed that the removal efficiency of Zn²⁺ is highest when the adsorption temperature is 25 oC and adsorption time is 30 min.The removal efficiency of Zn²⁺ was retained about 99.6%.The NaP zeolite doping metal can achieve depth of metal ion adsorption.The concentration of Zn²⁺ is reduced to less than 0.5 ppm.