The Study Of Adsorption Characteristic Of Ca～(2+), Mg～(2+), Na～+ And K～+ Ions Onto Hydrothermal Modified Natural Clinoptilolite

Liaoning Fuxin natural clinoptilolite was modified by hydrothermal method in this study.Physical chemistry characteristics, chemistry composition and characteristics of potassium ionon the modified clinoptilolite were made a systematic study. Especially, the research studiedthe competitive adsorptionin the two kinds (Na, Ca, K, and Mg) of the caiton mixed solutionand the four cations mixed solution. The modified clinoptiloite was made to zeolite membrane,which can offer certain theoretical foundation on developing and utilizing clinoptilolite suchas extracting potassium from seawater, and adsorption-separation potassium from the mixedsalt solution.Firstly, systematic research about modifying clinoptilolite by hydrothermal method wasmade.Under the different hydrothermal modified condition, the hydrothermal reactioncondition was optimized, the research determined the different modified clinoptilite cationexchange capacity in the solo system. From the result, the high selectivity and moreadsorption capacity hydrothermal modified clinoptilolite was obtained (K⁺ of cation exchangecapacity of modified clinoptilolite was 1.912mmol/g, natural clinoptilolite was 1.203mmol/g).And it showed modified clinoptilolite potassium ion exchage capacity was larger than naturalclinoptilolite 60%, and we found the relationship between tha Si/Al ratio and cation exchangecapacity:the Si/Al ratio became the lower, the K⁺ ion exchange capacity became larger. Whenthe Si/Al ratio of clinoptilolite was 4.9, the ion exchange of the K⁺ was the largest.Secondly, the potassium ion thermodynamics adsorptionon modified clinoptilolite wasmeasured through equilibrium adsorptionisotherms. The influence of the existence ofcompeting cations such as Na⁺, Ca²⁺, Mg²⁺ was measured, anion, pH of the solution,contacting time and the effect of the phonel. From the result, the cations ion exchage orderwas determined, which was K⁺＞NH₄⁺＞Na⁺＞Ca²⁺＞Mg²⁺, the contacting time was 140 minituesand when the pH of the solution was 6, the cation exchange was the best. The effect of SO₄^2-and HCO₃^- was lower than Cl^-, Br^- and I^-. The phonel was in existence in the solution, whichcould restrain the clinoptilolite to absorb the potassium.Thirdly, the reaserch was used chemic method to measure the clinoptilolite Silicon andAluminum, the changed Si/Al ratio was used FT-IR to express, and XRD was used to expressthe clinoptilolite structure transformation on the modified process. XRD was clearly showedthe hydrothermal modified mothed could hold clinoptilolite structure very well. And the research analyzed the ion exchange mechanism and zeolite hydrothermal reaction mechanism.The Langmuir and Frundlich equation were tested using the experimantal data of potassiumion on modified clinoptilolite to obtain the best fit. The result showed the Frudlich isothermalequation was fit for the clinoptilolite adsorption behavior.Finally, the clinoptilolite was made to be two kinds of zeolite membrane, the firstmethod was based the clinoptilolite high adsorption selectivity, and the second method wasbased electrodialysis membrane principium. The first method, the zeolite membrane wasoperated easily, but the effect of the separation potassium in the salt solution was bad and thefelted clinoptilolite colud brash off in the salt solution. The second one had clearlysurperiority, with the low voltage(30V-40V), which could separate potassium form the saltsolution very well, especially in the Ca/K, Mg/K system. The transmited Ca²⁺ and Mg²⁺ waslower than 10%, but transmited K⁺ was larger than 60%, which was good to use separate theK⁺ from the mixed salted solutin that had lots of Ca²⁺ and Mg²⁺.