| Ceramic membrane separation is a kind of separation technology with a broad prospect to application,especially the development and utilization of functional ceramic membrane.So this paper reviewed the preparation methods of charged ceramic membrane.And with diatomite ceramic as base membrane,Y2O3 as charged agent,the preparation of positively charged micro-porous functional ceramic membrane(hereinafter referred to as charged membrane)and its performance characterization were studied.Firstly,the charged membrane was prepared through three methods and the membrane structure and performance was characterized by DSC-TGA?XRD?BET?SEM and so on.Three methods of preparation membrane were synthesized and the main conclusions were as follows:? The membrane process of dispersant method is simple.However,charged agent in the dispersion process was easy reunion,and poor stability.The binding force is not strong between Y2O3 and base membrane.So this method was not an ideal way to prepare charged membrane.? Using alkali method,nano-Y2O3 on base membrane surface distributed uniformly,and there was strong adhesion between nano-Y2O3 and base membrane.But it must remove the by-product NaCl during the process of preparation.And the removal technology routine was tedious,especially wasting water resources.Furthermore,it didn't achieve the ideal effect to remove titan yellow for charged membrane.? It possessed more advantages using urea method to prepare charged membrane,such as:fine distribution of nano-Y2O3,strong bonding force,Y2O3 not easy to fall off from membrane surface and high removal efficiency for titan yellow.Therefore,this article prepared the charged membrane using urea method.Secondly,the paper studied the process of preparation charged membrane by urea method:the best experimental conditions for liquid coating preparation is n(YCl3)/n(urea)=1:6,reaction temperature 95?,reaction time 110min;Membrane pore structure was kept well when coating liquid concentration was 0.05mol/L and coating time was 2 times.Moreover,nano-Y2O3 particles distributed uniformly on the membrane surface;Precursor of Y(OH)CO3·H2O decomposed and OH-,CO32-groups disappeared when the calcined temperature was 700 ?.And then precursor transformed into nanometer Y2O3.Through characterization,pure Y2O3 crystal particles grown well,and attached uniformly on the surface of micro-porous membrane.Finally,bonding force between Y2O3 and base membrane,electric properties of membrane surface and filtration performance were researched.The results shown that Y2O3 and base membrane was combined with chemical bonds,and the c(Y3+)=0.065mol/L in filtrate during the filtration experiments.These indicated that it combined strongly between Y2O3 and base membrane and Y2O3 was not easy to fall off from membrane surface.The iso-electric point of charged membrane was 8.27,and it showed strongly positive electrical property on membrane surface in pH range of 4-8.The removal rate of charged membrane to negative titan yellow was up to 99.6%.And the charged membrane also exhibited an ideal effect for enriching bacteria.In conclusion,the urea method prepared charged membrane had many advantages of less technological process and low cost.Nano-Y2O3 uniformly distributed charged membrane surface.And it had strong bonding force between base membrane and charged agent.So the positive charged membrane could remove negative particles in water such as organic small molecule dyes,bacteria and so on,and achieve the deep purification of water quality.This provides a new idea for broadening the application and development of functional ceramic membrane. |
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