Preparation And Adsorption Properties Of Imprinted Chitosan Resin

Chitosan is characteristic of rich reserves, biocompatibility and easy biodegradation which can chelate reaction and adsorption of heavy metal ions by its rich amino and hydroxy groups. Chitosan has a vast application prospect in terms of separation and enrichment of heavy metals.In this work, Cu-ICM( Imprinted chitosan microspheres using Cu2+ as imprinted ion) was prepared by inverse suspension polymerization in microwave radiation synthesis instrument with ion imprinted technology, used chitosan as functional monomer and used Cu2+ as template molecule. The structure of Cu-ICM was characterized and its adsorption properties was studied. EMICM( Ethylenediamine-Modified Magnetic Imprinted Chitosan microspheres using Cu2+ as imprinted ion) was prepared by adding magnetic and chemical grafting onto Cu-ICM.Optimize the preparation conditions of Cu-ICM through single factor experiments and orthogonal experiments. The preparation conditions are preferably as follows: the concentration of chitosan solution is 2%(w /w), the amount of copper acetate is 50 mg, the crosslinking agent(10% glutaraldehyde solution) amount is 0.8 ml, stirring speed is 600 r/min, microwave heating temperature is 45℃, the crosslinking reaction time is 5 min, 3% Na OH curing time is 2.5 h.Cu-ICM was characterized by four ways. It can be seen from SEM that the microspheres are preferably spherical and the surface is full of slots. FT-IR analysis showed that-NH2 and –OH are involved in the chelation reaction with Cu2+. TGA analysis showed that Cu-ICM gets lower thermal stability than chitosan. XRD analysis showed that the crystallinity of the Cu-ICM reduced. Many physical properties such as the degree of swelling, the moisture content, acid dissolution rate, mechanical strength, packing density of CTS,Cu-ICM and NICM were studied, the results showed that the physical properties of Cu-ICM meet its requirements of apply to copper-wastewater treatment and it has a higher adsorption capacity than NICM.The adsorption properties of Cu-ICM were studied, the best conditions of adsorption are: Cu2+ initial concentration is 300mg/L, p H of solution is 5, adsorbent dosage is 0.06 g, adsorption time is 4 h. Adsorption thermodynamics studies showed that the adsorption process is more in line with the Langmuir adsorption isotherm, belongs to a chemical adsorption process of single molecules. Under the experimental conditions, the maximum adsorption capacity for Cu2+ on Cu-ICM reached 119.7 mg/L. By the calculation of enthalpy, entropy and Gibbs free energy change, know that the adsorption is spontaneous, endothermic, disorderly and the process is controlled by entropy change. Adsorption kinetics study showed that the adsorption process is more in line with pseudo-second order kinetic model, adsorption process is controlled by a chemical reaction. Selective experiments showed that, the adsorption capacity of template ion adopted on Cu-ICM was higher than that of NICM, he adsorption capacity of template ion was higher than that of untemplate ion, description that ion imprinting technology can not only improve the adsorption capacity, but also improve the selectivity. In addition, Cu-ICM has good regeneration and reuse of properties, after seven times reuse, it keeped a high adsorption capacity.Magnetic and grafted material were add onto Cu-ICM in which way ethylenediamine-Modified Magnetic Imprinted Chitosan microspheres using Cu2+ as imprinted ion was prepared. The optimized preparation conditions were:the amount of epichlorohydrin is 1 ml, crosslinking time is 10 min, ethylene diamine dosage is 0.8 ml and graft reaction time is 6 min. EMICM is characteristic of excellent magnetic response performance, ease of separation, and a high adsorption capacity.In sum mary, Cu-ICM and Cu-ICM can be used to selectively separated Cu2+ from the waste water or enrich it, they get a very adsorbent future.