海藻酸钠-醋酸纤维素复合薄膜的制备及除湿性能测试

Preparation and dehumidification properties of sodium alginate-cellulose acetate composite membranes

为提高膜式全热交换器的除湿效率,以海藻酸钠为表面活性层,醋酸纤维素膜为支撑层,氯化锂为亲水添加剂制备了一种新型除湿复合膜。测试了复合膜的水蒸气透过量和水溶性,对薄膜结构进行表征及分析了应用复合膜的全热交换器的传质系数。研究结果表明:复合膜的水蒸气透过量随氯化锂含量增加而高达4.42×10^(-5)g·m^(-2)·s^(-1)·Pa^(-1),是无氯化锂复合膜的1.56倍,商用纸膜的2.63倍。表面活性层水溶性介于18.29%~28.55%之间,具有一定的防水耐水性。热重曲线表明通入55℃干燥空气复合膜可实现再生,红外光谱图显示出海藻酸钠为复合膜引进大量亲水性羟基。最后,将复合膜应用到全热交换器中,并与商用纸膜换热器在传质系数上进行了分析比较。

In order to improve dehumidification efficiencies of membrane-based energy recovery ventilator（ERV）, composite membranes based on cellulose acetate, sodium alginate and lithium chloride（LiCl） were fabricated. Cellulose acetate was adopted as supporting constructions and sodium alginate and LiCl were the corresponding active layer and hydrophilic additive. Then their key characteristics were tested and analyzed to investigate practical performance in the ERV. The highest permeance of composite membranes reaches up to 4.42×10-5g·m-2·s-1·Pa-1, which is 1.56 and 2.63 times higher than those of the asymmetric membrane without LiCl and the traditional commercial paper, respectively. Water solubility of the modified active layer ranges from 18.29% to 28.55% for cross-linking improves the waterproofness. Moreover, thermal gravity curves indicate membranes can be regenerated by contacting 55℃ dry air. Fourier transform infrared spectra illustrates that there are plenty of hydrophilic hydroxyl groups on the surface of composite membranes. Finally, the total mass transfer of ERV composed by the composite membranes is analyzed and compared with the commercial one. These properties demonstrate this membrane has great potential to be applied on the ERV.