Forward Osmosis Performance of Sodium Polyacrylate as Draw Solution
QI Yuan-feng LI Yu-ping LI Hai-bo CAO Hong-bin WANG Shao-na
Key Laboratory of Green Process and Engineering, Institute of Process Engineering, CAS Institute of Processing Engineering ，CAS Institute of process engineering, Chinese Academy of Sciences Institute of Processing Engineering ，CAS Institute of Process Engineering, Chinese Academy of Sciences
Abstract：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.