Synthesis And Adsorption Properties Of Cyclodextrin Polymers Crosslinked By Multicarboxylic Acids

Synthesis methodology and structure design of cyclodextrin polymers (PCD) have got tremendously attention these years, especially the cyclodextrin crosslinking polymers as well as their application in separation, medicine, disposal of environment pollutions, and so on. Earlier studies have shown that adsorption properties of PCD have a close relationship with the kind of crosslinked agent and crosslinking density. This article synthesized several new multi-acids and its crosslinked polymers with CD; and studied the adsorption properties of these polymers on dyes.1. One novel tricarboxylic acids-diethylenetriamine maleamic acid(Tri-acid) was synthesized by maleic anhydride and diethylenetriamine. Its structure was characterized by IR,1HNMR and MS. Tri-acid crosslinked withβ-CD to get PCD-tri and the structure of PCD-tri was characterized by IR,13CNMR, TG, and SEM. Another crosslinked polymers (PCD-di) was synthezised by ethanediamine maleamic acid (Di-acid) andβ-CD through a modified method. It was characterized by IR, DSC-TG and SEM.2. Adsorption properties of PCD-tri and PCD-di with different molar rate of CD and crosslinked agent on basic fuchsin (BF) and methylene blue (MB) showed that the best adsorption efficience was PCD-tri for1:2and PCD-di for1:4.3. The influences of adsorption conditions (pH, temperature and salt concentration) on the adsorption capacity(QA) of PCD-tri(2) and PCD-di(4) adsorbing BF and MB were studied. Results showed that Qe increased with the increase of temperature at15～35℃, increased with the increase of pH and decreased with the concentration increasing of NaCl at25℃. The saturated adsorption capacities was124.82mg.g-1(pH6.34) for BF and146.13mg·g-1(pH6.00) for MB with solid-to-liquid ratio1g·L"1for PCD-tri(2) while the saturated adsorption capacities was124.82mg·g-1(pH6.34) for BF and146.13mg·g-1(pH6.00) for MB with solid-to-liquid ratio1g·L-1for PCD-di(4). The pseudo-first-order, pseudo-second-order and intraparticle diffusion models were applied to fit the experimental data in this work; The adsorption equilibrium data were analyzed by the virtue of Langmuir, Freundlich isotherm equations. Results indicate that the adsorption of BF and MB onto PCD-tri(2) and PCD-di(4) fits the pseudo second-order rate model; Langmuir isotherm model could well describe the adsorption equilibrium process. the calculated thermodynamic parameters showed that the adsorption process was endothermic, entropy increase and spontaneous.4. The y-cyclodextrin polymer(P-y-CD-tri) was synthesized and characterized by IR and TG. Adsorption properties towards some organics were researched. It was shown that P-y-CD-tri has better adsorption properties than PCD-tri(2) toward BF, Rhodamine B and Quercetin. And P-y-CD-tri can selectively adsorb Methyl orange and Rutin.