The Application Researching On Adsorption And Separation Of Potassium Ionic With The Dibenzo-18-crown-6-polyurethane Foam

At present there was a problem in the technique of producing potassium salt. It was that the waste brine destroyed the ecological environment and the resource of potassium. It was necessary to advance new method to improve resource using efficiency and solve the problem, because the resource of potassium was limited in our country.Novel macromolecule material dibenzo-18-crown-6-polyurethane foam was prepared with dibenzo-18-crown-6 as the function group. It could adsorb potassium ionic with higher selectivity. The property of adsorbing potassium ionic and recycling was also researched.Synthesis of dibenzo-18-crown-6 using the ultrasonic synthesis method and the structure of dibenzo-18-crown-6 was characterized with IR, elementary analysis, UV and 1^H NMR. Dibenzo-18-crown-6-formaldehyde polymer was synthesized using the dibenzo-18-crown-6 and formaldehyde in solution of formic acid. The structure of dibenzo-18-crown-6-formaldehyde polymer was characterized with IR. The Crown ether polyurethane foam was synthesized using Polyether:100 , dibenzo-18-crown-6-formaldehyde polymer:30, H2O:5, silicone oil:1.52, DBTD:0.24,TDI:63, the temperature of materiel had needed to control between 20 and 25℃. Thermogravimetric Analysis was carried out for crown ether polyurethane foam. Experimental results show that the novel absorption material had good thermal stability under 200℃.Solution's pH and the equilibrium adsorption time were the most factors for the efficiency of adsorbing and separating potassium ionic by crown ether polyurethane foam. The optimum conditions of static adsorption experiments were obtained by the condition experiment: the equilibrium adsorption time 4 hours; the adsorption temperature 20℃; the solution's pH=7. Crown ether polyurethane foam for adsorbing K⁺ with higher selectivity and higher adsorption capacity, and its adsorption capacity of K⁺ was 16.76 mg/g, was 6.16 times of common polyurethane foam. In selective experiments, the selectivity coefficient of K⁺ was 1.97 times of Na⁺, 16.85 times of Mg²⁺, 3.35 times of Ca²⁺. Therefore, the crown ether polyurethane foam had a high selectivity for K⁺ in this mixed solution. The novel crown ether polyurethane foam had a good regeneration performance. After repeated regeneration for six times, the adsorption of crown ether polyurethane foam had a minor decline, its adsorption capacity of K⁺ was reduced to 92.59%. It showed that the adsorption of this adsorbent was stable, it could be reused for many times.