The Research On The Synthesis Of Crown PU Foam And In Separation Of Lithium And Magnesium

The applications of Lithium and its compounds are more and more extensive. But extracting Lithium from the Salt Lake has been a major problem in China. Crown is a kind of synthesized circinal multidentate ligands, which is widely studied. The molecules of them have not only external hydrophobic skeleton, but also hydrophilic cavity, so they can complex cations and neutral molecules by dipole-ions and hydrogen bonding respectively. As for crown's special complexation with cations and selectivity of coordination, they have important application value in separation of ions. Structure determines the performance. Crown's unique configuration characteristic is closely related to the stability and selectivity of the complex compound with cations.In this paper, took the catechol, 1,3-dibromo-propane as raw materials and the lithium hydroxide as templating agent. They reacted in solution of dimethyl sulfoxide. The reaction temperature, reaction time, ratio of raw materials was controlled, the optimal reaction conditions was found. The results showed that: the template method combined with ultrasonic in two steps. The reaction was at 60℃under ultrasonic for 3h, and molar ratio of catechol to 1, 3- dibromo propane was 1:1. the yield would up to 42.6%. Their products by elemental analysis, infrared spectroscopy, nuclear magnetic resonance spectroscopy characterization show that synthetic products were DB14C4.Then formaldehyde and dibenzo-14-crown-4 occurred condensation reaction catalyzed by formic acid. On the basis of this, we synthesized phenolic resin-based crown polymers. The synthesized compound was characterized by means of infrared spectroscopy, differential thermal analysis etal. The result showed that, the synthesized compound was the target product. And then synthetic compound was mixed with polyurethane foam, so the traditional polyurethane foam was modified. Optimum ratio of raw materials: Polyether polyol: 25 g, dibenzo-14-crown-4:0.9 g, dimethyl silicone oil: 0.225 g, dibutyltin February acid: 0.05 g, Triethylenediamine: 0.0375 g, distilled water: 0.775 g, TDI:11.25g. Finally, we got crown polyurethane foam, whose appearance and properties are relatively stable.Adsorption test was carried on a certain concentration of lithium and magnesium ions. The impact of pH, temperature, time were all considered, so as to obtain the optimum conditions of the static adsorption(Time:4 h, pH :7,the temperature : 25℃). The compounds were eluted after the adsorption of metal ions, and the regeneration of its function experiment was carried. Measured the adsorption capacity of the eluted crown polyurethane foam.Its maximum adsorption capacity of lithium ion is 0.5689 mmol·g^-1. Each adsorption elution adsorption capacity decreased less than 5 % after Regeneration, adsorption capacity over 0.50 mmol·g^-1,which proves the purpose of reuse can be achieved.