Preparation And Application Of Highly Selective Lithium Ion Adsorbents

In this study,a functional monomer methacryloyoxyme-12-crown-4?M12C4?was first prepared using 2-hydroxymethyl-12-crown-4 and methacryloyl chloride,which can form a stable complex with Li⁺.Then M12C4 was used to prepare adsorbents by suspension polymerization with two groups of substances:?1?styrene?St?and divinyl benzene?DVB?,?2?methacrylate?MMA?and trimethylolpropane trimethacrylate?TMPTMA?.The chemical composition of the adsorbents was confirmed by nuclear magnetic resonance?NMR?.The porous structure was analyzed using BET.The adsorption kinetics,adsorption isotherm,the effect of solution pH,adsorption selectivity and reusability were studied respectively.For the adsorbents with St as monomer and DVB as cross-linker,the content of M12C4 was controlled at 10%and 20%successfully.The adsorption behavior could be described by Langmuir model and Pseudo-second model,meaning that Li⁺adsorption on the adsorbents was primarily homogenous and chemical.For the adsorbents with 10%M12C4,when the temperature was 25 ^oC,the solution pH was 7,the initial Li⁺concentration was 80 mg/g,the maximal adsorption capacity reached 1.85 mg/g after180 min adsorption.For the adsorbents with 20%M12C4,the maximal adsorption capacity was 3.38 mg/g under such condition.As for the adsorbents with MMA as monomer and TMPTMA as cross-linker,the content of M12C4 was also controlled at 10%and 20%.Langmuir model and Pseudo-second model was also suitable for the adsorption process.When the temperature was25 ^oC,the solution pH was 7,the initial Li⁺concentration was 80 mg/g,and the adsorption time was 180 min,the maximum adsorption capacity was 2.31mg/g?10%M12C4?and 3.91 mg/g?20%M12C4?,respectively.Moreover,all the adsorbents showed adsorption selectivity for Li⁺in a mixture solution with Li⁺,Na⁺,K⁺,Mg²⁺,and Ca²⁺.The adsorbents also showed good reusability with no significant decrease in adsorption capacity.