| The recent research progress of polyepichlorohydrin-based chelating resins and liquid crystalline polymers was introduced in this paper, based on these reseaches, a series of chelating resins with polyepichlorohydrin as the main chains and rigid biphenyl mesogen as the side chains with (or without) terminal pyrrole ligand was designed and prepared, and the synthetic technology was also studied. The chemical structures of products were confirmed by FT-IR and 1H NMR. Ten resins prepared can be divided into three sorts by their molecular structure, i.e., PnCP, HPnCP (n=6,4,2) and HPx (x=a,d,CN,e). Polarizing optical microscope (POM) equipped with hot-stage and differential scanning calorimeter (DSC) were employed to investigate phase behavior and thermal properties of the compounds, and the results showed that PnCP was a kind of polymers with amorphous glass state and HPCN with liquid crystalline, and other products were all semi-crystalline polymers. It indicated that the molecular weight of polyether and mesogenic structure in the side chain have a great effect on the phase sorts of products:higher molecular weight and mesogen with stronger polarity were favorable to enhancing orientation of products. Additionally, the thermal decomposition of resins was studied by thermogravimetric analysis (TGA), and the results showed that the beginning decomposition temperature of resins was upon 290℃, therefore they all exhibited excellent thermostability. The substitution degrees of resins increased along with an increasing yield as a whole. Although the resins which belonged to identical sort have different substitution degrees, their thermal properties (phase transition temperature) were almost identical, indicating that there have some correlation between the mesogenic structure and its grafting reaction activity.A series of conventional adsorption properties of chelating resins, e.g., static maximum adsorption capacity for single metal ion, effect of pH values on adsorption, adsorption kinetic, isothermal adsorption and regeneration properties of resins et al., have been investigated. Their results showed that, the resins have a higher adsorption capacity for Cu(Ⅱ), Hg(Ⅱ) and Co(Ⅱ), and a medium adsorption capacity for Cd(Ⅱ), Zn(II) and Pb(Ⅱ), but a very poor adsorption capacity for Mg(Ⅱ) and Ni(Ⅱ), so they presented a excellent adsorption selectivity for abovementioned metal ions; pH values have a greater effect on adsorption properties and which have different expression forms along with different metal ions; the resin's adsorption equilibrium time to Cu(pH4) and Hg(pH4) is 2.5h and 4.0h, respectively, and the adsorption process can be described with GE.Boyd liquid film diffusion equation; the equilibrium concentration of Co(Ⅱ) and Cd (Ⅱ) was (0.06-0.08)mol/l when adsorption capacity of the resins was saturated, and the adsorption isotherms of HP4CP for Co(II) and Cd(II) and that of HP2CP for Co(II) can be described by Langmuir or Freundlich isotherm equation, whereas the adsorption isotherms of HP2CP for Cd(II) can only be described by Freundlich isotherm equation; in addition, the resins presented excellent regeneration properties with an upon 94% desorption rate after three times reuse.In order to investigate the effect of resinic orientation on adsorption performance for metal ions, we have obtained the crystalline (or liquid crystalline) state with higher orientation degree and isotropic state with lower orientation degree by annealing and quenching thermal treatment on five semi-crystalline (or liquid crystalline) resins prepared, respectively. The results indicated that there were some differences on adsorption capacity for a given metal of resins under different thermal states, and these differences have better regularities which have different form to every specific metal ion. So it's expected to enhance the adsorption selectivity for a given metal ion by modifying the orientation degree of resins. Additionally, the correlative mechanism of adsorption was investigated from the point of the matching degree between resinic molecular mean space and effective hydrated metal ionic radius as well as the principle of the hard and soft acids and bases (HSAB), by means of abovementioned theories, we can successfully explain the especial adsorption behavior of liquid crystalline resin which was different from that of crystalline resins.Subsequently, we have dissolved the linear polyether chelating resins into chloroform and investigated the adsorption properties of resins in the form of solution state. The results showed that, for Mg(pH10), Cu(pH5), Hg(pH4), Cu(pH8) and Cd(pH8), the adsorption capacity of solution-state resins was higher than that of corresponding solid-state resins; whereas, for Cd(pH5), Co(pH5) and Zn(pH8), the opposite happened; and for Zn(pH5) and Pb(pH5), there was no obvious regularity, nevertheless, liquid phase extraction for Pb(pH5) may be influenced by resin's molecular weight. Additionally, the special research on the abnormal adsorption for Hg2+of resins containing porrole has been done. By XPS detection, HgO was found to be abundant in the sample, indicating that the hydrolysis of Hg2+continuously occurred in the resinic solution layer with weak alkaline, which resulted in the concentration of Hg(2+)in aqueous phase decreased greatly and apparent super high adsorption capacity (11.57mmol/g) of the resins. |
