热处理条件对煤基陶瓷-炭复合膜性能的影响

Effect of heat treatment conditions on properties of coal-based ceramic-carbon composite membrane

以煤萃取反萃取法分离所得密中质组分溶胶为涂覆液,经成膜和炭化,成功制备了煤基陶瓷-炭复合膜.研究了炭化条件对制备的复合膜性能的影响,考察了复合膜的孔隙率、纯水渗透率以及对Fe(OH)_3胶体和牛血清蛋白溶胶(BSA)的截留率与炭化工艺条件的关系,探讨了分离层的热演化过程与机理.结果表明:炭化过程中的升温速率、中间恒温温度、中间恒温时间和炭化终温均会影响分离层热解气体和液相的生成速率以及黏连固相成为胶质体的状况,进而影响分离层的孔隙结构和分布,并最终影响所制复合膜的孔隙率、渗透率和截留率;对Fe(OH)_3胶体具有较好截留效果的炭化条件为:升温速率为4℃/min,中间恒温温度和时间分别为460℃和20min,炭化终温600℃;对BSA溶胶具有较好截留效果的炭化条件为:升温速率4℃/min,中间恒温温度和时间为490℃和20min,炭化终温为800℃.密中质组分的特定组成结构使其在热解炭化过程中主要生成胶质体液相物质和气态产物,基本不产生膨胀作用,这一特性非常有利于密中质组分制备复合膜分离层.

The sol of the coal dense medium component which was produced by the extraction and stripping method was chosen as the coating solution. Through the filming and charring, it was successfully prepared as coal-based ceramics-carbon composite membranes. The effects of carbonization conditions on the performance of the composite membrane prepared were studied, and the relationships between the carbonization process conditions and the Composite membrane porosity, water permeability as well as rejection rate of the Fe（OH）3 colloidal and bovine serum albumin （BSA） sol were inspected. Then thermal evolution process and mechanism of the separation layer were discussed. The results show that the heating rate, intermediate constant temperature, the intermediate holding time and final carbonization temperature in the carbonization process will affect the generation rate of the separation layer pyrolytic gas and liquid, as well as the state of adhering the solid becoming metaplast, thereby affect to the composite carbon membrane separation layer pore structure and distribution, and ultimately affect porosity, permeability and retention rate of the composite membrane; under the following carbonization process conditions, heating rate with 4 ℃/min, intermediate constant temperature and time at 460 ℃ and 20 min respectively, final carbonization temperature at 600 ℃, the composite membrane has better retention rate on Fe（OH）s colloids~ under the following carbonization process conditions： heating rate with 4 ℃/min, intermediate constant temperature and time at 490 ℃ and 20 min respectively, final carbonization temperature at 800 ℃, the composite membrane has better entrapped results on the BSA sol. The coal dense medium component major generates liquid and gas phase material in pyrolysis carbonization process due to its specific composite structure, and substantially no swelling effect in the process, this feature is very conducive to prepare composite membrane separation layer by the coal dense medium component.