| Amorphous metal phosphates have long been known and received widespread attention from 1955 to 1965,especially their potential use as inorganic ion exchangers in processes that occur under high temperature or high doses of ionizing radiation.Taking?-tetravalent metal phosphate as an example,the oxygen belonging to the PO43-tetrahedron group can be shared with the tetravalent metal in an octahedral configuration in different ways and in different numbers.They are typical cationic layered compounds which have lots of H+in the interlayer space,and thus own a strong capability of cation exchange.In this study,a diamine pillared?-titanium phosphate intercalation compound was prepared by direct ion exchange method using?-titanium phosphate as the target,the carbon chain of the intercalated diamine increased from(NH2(CH2)nNH2,)n=2 to 7.The pH value and temperature of the reaction system was investigated using 1,3-propanediamine as a pillaring agent.Various characterization results show that the interlayer distance of?-titanium phosphate is extended from 7.6(?)to 15.23(?).The layer space structure consists of a single molecule,the average inclination angle between the alkyl chain and the laminate is 75.6°.Finally,in a weakly acidic environment,the direct ion exchange method is more effective,and the temperature has little effect on the intercalation.When a cyclic amine is used as the intercalation main body,the cyclic amine is neutralized with phosphoric acid to prepare a phosphate solution,and an intercalation product is obtained by a direct ion exchange method.Various characterization results show that aniline,phenylenediamine,benzylamine,phenethylamine,imidazole,and N-methylimidazole can be embedded in the layers of?-titanium phosphate,and the laminate structure of?-titanium phosphate remains intact.destroyed.However,pyrazine,pyrimidine,and pyridazine cannot be embedded in the interlayer of?-titanium phosphate by this method.This is mainly related to the embedded p Ka of the guest,which greatly controls the content of the embedded guest molecules of the layered phosphate and the structure of the host compound.Basic guests can be intercalated into the interlayer of?-titanium phosphate by a direct ion exchange method,and the aqueous solution of the guests that cannot be intercalated is generally acidic.The 1,3-propanediamine was rapidly pillared to the?-TiP layer by direct ion exchange method,and the composite material?-Ti(HPO4)2·0.8NH2(CH2)3NH2·0.29H2O(?-TiPPda)was obtained.The materials before and after the intercalation were applied to the extraction and separation of Eu(?).The adsorption performance of Eu(?)in?-TiPPda and?-Tip were psystematically studiedunder different conditions(time,isotherm,kinetics,pH and competing ions,etc.).A simple investigation of its adsorption mechanism was carried out.It was found that when the solution pH=5,T=25?,t=2 h,m/V=1 g/L,the adsorption amount of?-TiPPda for Eu(?)reached 173.68 mg/g when?-TiPPda was used as adsorbent.While?-TiP was used as adsorbent,the adsorption value of Eu(?)reaches 37.7 mg/g,the adsorption effect of?-TiPPda on Eu(?)has been significantly improved.Moreover,it was found that the Eu(?)uptake is limited to the surface of a-TiP when it is used as sorbent.On the other hand,the Eu(?)uptake is considerably improved with a-TiPPda as a consequence of an ion-exchange process into the expanded interlayer space. |
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