正渗透应急水袋膜材料制备

Cellulose triacetate forward osmosis membrane for emergency water-bag

应急水袋是一种可以就地从不可饮用的水源中及时、有效得到饮用水的生命救援工具。本文研究了三醋酸纤维素(CTA)正渗透膜材料的制备,以及用于制备应急水袋的研究进展,并对水袋的汲水功能和重金属离子截留效果进行测试。结果表明,以0.5 mol/L NaCl为驱动液和去离子水作进料液的测试条件下,膜水通量达到8.77 L/(m^2·h),驱动溶质反向扩散比J_s/J_w约为0.56 g/L。以一定浓度葡萄糖为汲取液时,经5 h处理水袋可得到约180 g水,可满足人体维持生命所需的饮水量。选取Pb、Cr、Hg、As 4种典型的水体污染重金属为评价元素,渗透结果表明,该膜对半径尺寸在100 pm以上的粒子具有比较理想的截留性能,达到95%以上,Pb(II),Cr(III),Hg(II)3种重金属的处理效果能达到《GB5749—2006生活饮用水卫生标准》的要求,但是对于As(III)这种水合半径小于65 pm的离子其截留率较低,因此,膜材料皮层的致密性还需要进一步提高。

The emergency water-bag is a gadget for supplying drinking water under emergent situations. The preparation and the performance of the cellulose triacetate （CTA） forward osmosis （FO） membrane and the research progress of the emergency water-bag made of the CTA membrane are studied in this paper. The water flux and the rejection performance of the heavy metal ions of the emergency water-bag are tested in the homemade water. With this CTA membrane, a FO water flux of 8.77 L/（m^2·h） and JJJw of 0.56 g/L are obtained under a standard test condition using 0.5 mol/L NaC1 as the draw solution and the deionized water as the feed. The water-bag containing the glucose solution can draw 180 g water in the water-bag from the surface water sample and this water processing capacity can meet the water demand to sustain life. The rejection rate of the heavy metal with the hydrated ion radius larger than 100 pm can reach 95%, and the concentration of Pb（Ⅱ）, Cr（Ⅲ）, and Hg（Ⅱ） in the water-bag is found to be lower than the National drinking water standard （GB5749-2006）. The As（Ⅲ） concentration in the produced water is higher than the standard, because the radius of the hydrated As（Ⅲ） is less than 65 pm. Further improvement in the FO membrane dense layer is required to remove micro-particles at a high rate.