Preparation Of APTES-B₄C-TiO₂/PVDF Mixed Matrix Membrane And Its Photocatalytic Degradation Of RhB Dyes

Industrial development is accompanied by the production of a large amount of organic wastewater,and the discharge of this wastewater into water bodies will cause great harm to human beings and the environment.The use of traditional wastewater treatment technologies including physical adsorption,biodegradation,catalytic oxidation can purify the generated wastewater to a certain extent.However,these methods generally have problems such as adsorption saturation,high operating cost,and incomplete decomposition of pollutants.The combination of photocatalyst and membrane can not only solve the problem of photocatalyst recycling and film blockage but also can use the synergy of polymer film and photocatalysis to achieve the purpose of efficient degradation of pollutants.In this work,nano-boron carbide（B₄C）was successfully introduced into polyvinylidene fluoride（PVDF）membrane matrix by immersion precipitation method to prepare B₄C/PVDF mixed matrix membrane with efficient degradation of organic dye solutions.The prepared composite membranes were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,energy dispersive X-ray analysis（EDS）,and water contact angle measurements.The photocatalytic performance of B₄C/PVDF composite membrane was investigated using 60 mg/L Rhodamine B（Rh B）and methylene blue（MB）aqueous solution as simulated wastewater.The results showed that the performance of the membrane was improved after the introduction of B₄C particles:the pure water flux increased from 120 L/m²·h to 210L/m²·h;the rejection rate for Beef serum albumin（BSA）solution increased from 77.1%to99.1%.Ffuthermore,when the content of B₄C was 4 wt.%,the photodegradation efficiency of B₄C/PVDF composite membrane was relatively higher,and the degradation efficiencies of Rh B and MB dyes were 79%and 78%,respectively.In order to optimize the PVDF composite photocatalytical membrane for degrading organic dye solution,B₄C/Ti O₂（Titanium dioxide）particles were further functionalized with 3-aminopropyltriethoxysilane（APTES）and added to the PVDF solution to prepare APTE-B₄C-Ti O₂/PVDF composite membranes via immersion precipitation method.The effects of PVDF content,the APTE-B₄C-Ti O₂ content as well as the ratio of nano-Ti O₂ to B₄C in APTES-B₄C-Ti O₂ particles on the photocatalytical performance and pure water flux of the composite membranes were studied.The three influencing factors were optimized using the Box-Behnken optimization method to determine the optimum composite membrane with the best photocatalytic performance.In addition,the interacting effect between the three independent variables was explored.The results showed that compared with the PVDF concentration and the ratio of nano-Ti O₂ and B₄C in the composite particles,the content of the composite particles shows a more significant effect on the photodegradation performance of the composite membrane.Finally,under the optimum conditions of PVDF（17wt.%）,APTE-B₄C-Ti O₂ content（0.75wt.%）,ratio of nano-Ti O₂ to B₄C in the composite particles（1.48）,the composite membrane with the best photocatalytic performance was prepared.The degradation efficiency for 60 mg/L Rh B solution was 88.01%,and the water flux of the membrane reached 254 L/m²·h.