Preparation Of Novel Modified Chitosan Microspheres And Preliminary Application

With the rapid development of society,people's quality of life and security awareness are promoting.It is undeniable that drinking water safety has always been the focus of attention in the whole society,especially the safety problems caused by microbial pollution.To solve this problem,there are two main ways,sterilization by high-temperature and using chemical disinfectants.However,the former is high cost,high energy consumption and inconvenience;the latter will have an annoying residual odor,and existing the"secondary pollution" risk.Thus,to develop safe,efficient and low price sterilization has become the important research direction.Immobilization technology is a sterilization method to immobilize bactericidal group with bacteriostasis onto soluble carrier,and to realize sterilization at room temperature,low residue and low energy consumption.This paper reviewed the immobilized sterilization agent and status quo of chitosan modification.Chitosan was chosen to prepare crosslinked chitosan microspheres with inverse suspension method.Furtherly,the ligand of strong bactericidal ability was introduced to crosslinked chitosan and the novel sterilization microspheres were obtained.Elemental analysis was used to study the optimal synthesis conditions.Based on the minimum inhibitory concentration(MIC)and minimum bactericidal concentration(MBC)test for Escherichia coli and Staphylococcus aureus,microspheres of excellent bactericidal properties were screened,and the properties and application of sterilization microspheres was studied.The main contents are as follows:1.Chitosan was crosslinked with propylene oxide.Under the condition of single factor experiment,the novel modified sterilization microspheres were synthesized by introducing the ligands with bactericidal function to crosslinked microspheres.The conversion rate of modified microspheres was calculated by elemental analysis.The best reaction solvent,temperature and mass ratio were judged according to the conversion rate.Under the optimum conditions,the grafting rates of ABTC,APC,DMTC and CCC were 39.4%,42.9%,33.1%and 44.2%,respectively.FTIR was used to characterize the structure of the modified microspheres and deduce the possible reaction routes.TGA was used to investigate the thermal stability of the microspheres.2.The microbicidal efficacy of the sterilization microspheres was evaluated by determining the MIC and MBC for Escherichia coil and Staphylococcus aureus.The results showed that ABTC and CCC microspheres had better bactericidal properties.In order to increase the additional value of the sterilized microspheres,the effect of Ag+ and Cu2+on the bactericidal effect of microspheres was studied.The results showed ABTC and CCC can still maintain good bactericidal effect.3.The ABTC and CCC were selected as the representative microspheres.By determining the content of extracellular DNA and RNA,and activity of TTC-dehydrogenase,the mechanism of sterilization was discussed.The metal adsorption and sterilization of the two kinds of microspheres were tested.The results showed that when the two kinds of microspheres were used to adsorb metal ions,the adsorption rate could be maintained at more than 95%after using 5 times,and it could be reused for 2 times as an efficient bactericidal agent.The thermal stability of microspheres was investigated using TGA.4.The bacteria-containing drinking water was passed through a sterilization column making of ABTC and CCC,and the test showed no microorganisms was found,which directly proved that ABTC and CCC modified sterilization microspheres has a good sterilization effect.