聚丙烯酸钠汲取液的正渗透性能

Forward Osmosis Performance of Sodium Polyacrylate as Draw Solution

研究了聚丙烯酸钠溶液作为汲取液的渗透压特性,并考察了影响水通量和溶质反向渗透量的因素和机制.结果表明,聚丙烯酸钠浓度与渗透压的关系符合维里方程,第二维里系数对渗透压有较大贡献,聚丙烯酸钠溶液浓度为0.2 g/mL时的渗透压达1.3 Osmol/kg以上,水通量为14.5 L/(m2?h),略高于相同渗透压的氯化钠汲取液[14.0 L/(m2?h)];聚丙烯酸钠汲取液的溶质反向渗透量为1.6 g/(m2?h),低于常规氯化钠汲取液的16.5 g/(m2?h).升高温度能迅速提高水通量,反向溶质渗透量维持在较低水平,聚丙烯酸钠汲取液适合比常规小分子汲取液更高的操作温度.聚丙烯酸钠汲取液较高的水通量和较低的溶质反向渗透量表明正渗透性能良好.

Osmosis property of sodium polyacrylate（PAA-Na） as draw solution was studied, and the forward osmosis performance of PAA-Na draw solution examined with focus on influential factors and mechanism of water flux and reverse solute flux. The results show that the fitting curve of osmotic pressure and PAA-Na concentration matches virial equation, and the second virial coefficient promotes the osmotic pressure dramatically in a certain concentration range; the osmotic pressure of 0.2 g/mL PAA-Na is over 1.3 Osmol/kg, showing the great possibility of PAA-Na as draw solution. The permeated water flux in the forward osmosis process with 0.2 g/mL PAA-Na as draw solution reaches 14.5 L/（m2？h）, which is higher than that of NaCl draw solution with the same osmosis [14.0 L/（m2？h）]. The reverse solute flux of 0.2 g/mL PAA-Na draw solution is only 1.6 g/（m2？h）, which is much lower than that of NaCl draw solution [16.5 g/（m2？h）]. The water flux increases significantly with the increase of temperature while reverse solute flux remains at low level, indicating that the suitable operation temperature with PAA-Na as draw solute should be higher than that with conventional small molecules as draw solute. PAA-Na is a good potential draw solute due to its great water flux and low reverse solute flux.