Preparation And Properties Of Modified CA Film And PA Film

Polyamide composite membrane and cellulose acetate membrane contained the characteristics of simple operation and outstanding separation which made its become the mainstream products. With the development of science and technology, put forward the higher requirements to the membranes, such as the higher water flux and higher rejection rate, yet the single organic polymer film cannot meet it. That is why the membrane's modification has became the research focus. In this essay, author selected the titanium dioxide, silver loaded titanium dioxide and oxidized high silver as the modifying agent, primarily modified the membrane surface, target to prepare the modified polyamide composite membrane and the modified cellulose acetate membrane. The specific research contents are as follows:?1? Cellulose acetate membrane were prepared using liquid/solid phase inversion method with cellulose acetate?CA? as film forming material, acetone and N-methylpyrrolidone?NMP? as mixed solvent and polyethylene glycol 400?PEG-400? as pore forming agent. The structure and morphology of cellulose acetate membranes were characterized by scanning electron microscope?SEM? and infrared spectroscopy?IR?. At the room temperature, cellulose acetate membrane was used to treat deionized water and 500 mg/L polyethylene glycol 600 at the pressure of 0.1 MPa to test the water flux and the rejection rate respectively. The effects of blend solvent content, reaction temperature and PEG-400 content on the separation properties of membrane were investigated. The results showed that when the NMP and PEG-400 were 60%?w? and 6%?w? respectively, and the reaction temperature was 60?, the prepared cellulose acetate membrane's water flux was 150.77 L/?m²×h¹?, and the rejection rate was 87.67%.?2? Experimental raw materials included cellulose acetate, acetone, N-methylpyrrolidone?NMP?, polyethylene glycol 400?PEG-400? and oxidized high silver that was a modifier.Under such conditions, hybrid membranes were prepared by liquid/solid phase inversion method. And the effects of oxidized high silver contents on the separation properties, morphology and antibiotic resistance of it were investigated. Experimental results show that oxidized high silver was beneficial to form the large pores and gave the hybrid membranes antibacterial property. When the oxidized high silver were 0.5%?w? the prepared hybrid membrane's water flux was 97.39 L/?m²×h¹?, along with the inhibition zone diameters for Escherichia coli and Bacillus subtilis were 7.2mm and 6.3mm, respectively.?3? With tetrabutyl titanate?TBT?, absolute alcohol and glacial acetic acid as raw materials, Ti O₂ was prepared by sol/gel method. Through XRD analysis, it was concluded that the prepared Ti O₂ was anatase, and belonged to tetragonal system. Along with CA membrane as the support layer, m-phenylenediamine?MPD? and trimesoyl chloride?TMC? as reactive monomer, triethylamine and N-hexane as solvent, sodium dodecyl sulfate?SDS? as surface active agent, and Ti O₂ as additive, in this conditions, Ti O₂/polyamide composite membranes were prepared by interfacial polymerization method. The effect of Ti O₂ contents and adding modes on the separation performance of the modified composite membrane were investigated. In addition, the membrane separation performance and the membrane antibacterial property were tested. Separation performance test results show that when the Ti O₂ content was 4%?w? in aqueous solution, water flux was 97.56 L/?m²×h¹?, and the rejection rate was 90.81%; However, when the Ti O₂ content was 5%?w? in organic phase solution, water flux was 122.85 L/?m²×h¹?, and the rejection rate was 92.91%. The results of antibacterial test showed that the composite membrane was provided with antibacterial properties.?4? Silver loaded titanium dioxide were added to the polyamide composite membrane by two methods, and the effects of the addition amounts on the separation performance of the composite membrane was explored. The best additive amount of the additive was determined by the membrane separation performance test. Results show that when the silver loaded titanium dioxide content was 0.9%?w? in aqueous solution, water flux was 91.56 L/?m²×h¹?, and the rejection rate was 90.46%; While when the silver loaded titanium dioxide content was 0.7%?w? in organic phase solution, water flux was 97.65 L/?m²×h¹?, and the rejection rate was 91.85%.