Pore Structure Modulation And Performance Characterization Of Ceramic-carbon Composite Membrane Separation Layer

With the using of dense medium component separated from raw coal by all group separation method as precursor,phenolic resin as additive,flat round ceramic as support,the dense separation layer was prepared by immersion coating and carbonization,then through the activation process to modulate the pore structure,ceramic-carbon composite membrane was prepared.In addition,the effects of membrane formation conditions,carbonization conditions,activation methods,and activation conditions on the composite membrane performance,and the bovine serum albumin(BSA)rejection rate were investigated.The mechanisms of dense composite membrane formation and separation layer pore structure modulation were analysed.The results show that:During the membrane formation process,along with the increase of phenolic resin dosage,continuous membrane layers are easier to form.The extending of coating time and coating times could improve the compactness,while the overlong coating time is unbeneficial to the formation of dense composite membrane separation layer.In the process of carbonization,the heating rate has influence on escaption of pyrolysis gas and further affects the porosity of the separation layer.Heating for a holding time at medium temperature is beneficial to the formation of continuous membrane with no cracks.The final temperature and holding time also have influence on the formation of dense composite membrane separation layer.The optimal conditions to prepare ceramic-carbon composite membrane with dense separation layer are: phenolic resin 15%,coating times 4 times,coating time 25 min,heating rate 3 °C/min,medium temperature 380 °C,medium time 90 min,carbonization temperature 500 °C,carbonization time 90 min.The optimal KOH activation conditions to modulate pore structure of composite membrane separation layer are: KOH solution soaking time 4 h,activation temperature 750 °C,activation time 30 min.The optimal water vapor activation conditions to modulate pore structure of composite membrane separation layer are: activation temperature 850 °C,activation time 2 h,water flow 0.25 mL/min.The effect of KOH activation on BSA is better than water vapor activation.A mount of small molecules are generated by dense medium component in the process of carbonization.Part of the small molecules escape as gas,the others left in the system as a solvent to form the liquid phase,allowing the system to maintain good liquidity.Pore structure is formed because of the gas escaption.Phenolic resin has a little weight loss at carbonization temperature,only a little amount of gases escape.It’s beneficial to the formation of dense composite membrane separation layer that pyrolysis residues of phenolic resin are trapped in the sytem to fill the pores left by volatile gases.Phenolic resin pyrolyse violently at activation temperature,generate a large amount of gases.But the dense medium component has been cured with dense structure.Therefore the gases pyrolysed by phenolic resin can’t escape,forming pores in the separation layer.KOH and water vapor react with carbon on the separation layer,open the internal pores to form pores that through the separation.In this paper,there are fifty figures,twenty two tables,one hundred and twelve references.