Study On Sterilization Performance Of Chitosan/TiO₂ Composites

Indoor air quality directly affects people’s lives,and the control of air pollutants has attracted more and more attention at home and abroad.As a common biological pollutant,the purification method of bacteria has become a research hotspot.Photocatalytic sterilization is an effective purification method,and chitosan,as a degradable organic material,also has good antibacterial effect.In this paper,chitosan/TiO₂ composite was prepared by compounding chitosan with TiO₂,and the properties of the composite were optimized in order to play the role of synergistic purification between them.In this paper,the sterilization performance of chitosan/TiO₂ composite was studied by combining experimental research with theoretical analysis.Firstly,chitosan/TiO₂ composites were prepared by impregnation method,and the loaded materials were tested and analyzed by scanning electron microscope,X-ray energy spectrum and Fourier transform infrared spectrum.Secondly,the single air duct experimental system was perfected,and the effects of PH value of pretreatment solution,TiO₂ immersion concentration,light source power,chitosan gram weight and cleaning times on the sterilization efficiency of chitosan/TiO₂ composite were studied.The resistance characteristics of the material were analyzed,and the sterilization performance of chitosan/TiO₂ composite was discussed with polypropylene substrate as reference.Finally,based on the single airway experimental system,the growth,reproduction and secondary pollution of bacteria on chitosan/TiO₂ composite were studied.The results show that TiO₂ loading on chitosan substrate does not cause obvious changes in functional groups.In the single-pass experiment,the sterilization efficiency of chitosan material firstly increases and then decreases with the increase of acidity of the treatment solution,and it is more advantageous to exert the sterilization performance under the condition of weak acidity with PH of about 6.TiO₂ and chitosan have synergistic purification effect,and the sterilization efficiency of the composite increases with the increase of the impregnation concentration of TiO₂.However,when the impregnation concentration is greater than 3%,the sterilization efficiency is not significantly improved by further increasing the impregnation concentration.The increase of the distance between the ultraviolet lamp and the filter material can effectively prolong the sterilization time of the ultraviolet lamp and improve the sterilization effect of ultraviolet itself,but the increase of the distance also reduces the light intensity acting on TiO₂,which leads to the weakening of photocatalytic sterilization effect.Under the test conditions of this study,the best distance is about 30cm.With the increase of the gram weight of chitosan,the sterilization efficiency of chitosan/TiO₂ composite is improved,but when the gram weight exceeds 190g/m²,the improvement of sterilization effect is not very significant.The resistance of chitosan/TiO₂ composites increases with the increase of gram weight,and shows a linear growth trend.The sterilization efficiency of chitosan/TiO₂ material after repeated cleaning is still high,which shows that this experimental method makes TiO₂ load on chitosan substrate relatively firm.When the concentration of TiO₂ is 3%,the survival rate of bacteria on the chitosan substrate per unit area is 24.4%of that of polypropylene substrate,and the bacteria shedding rate is 15.0%of that of polypropylene substrate.The chitosan/TiO₂ composite material can effectively hinder the growth and reproduction of bacteria and reduce the secondary pollution,which not only has good bacteria filtering effect,but also has good sterilization effect.