Ng How Y, Tang Wanling, Wong Wei S
Centre for Water Research, Division of Environmental Science and Engineering, Faculty of Engineering, National University of Singapore, Block EA #07-23, 9 Engineering Drive 1, Singapore 117576.
Environ Sci Technol. 2006 Apr 1;40(7):2408-13. doi: 10.1021/es0519177.
The performance of a forward (direct) osmosis (FO) process was investigated using a laboratory-scale unit to elucidate the effect of membrane structure and orientation on waterflux. Two types of RO membrane and a FO membrane were tested using ammonium bicarbonate, glucose, and fructose as the draw solution to extract water from a saline feed solution. The FO membrane was able to achieve higher water flux than the RO membranes under the same experimental conditions while maintaining high salt rejection of greater than 97%. Increasing operating temperature increased the water flux in FO process. To investigate the effect of membrane orientation on water flux, the FO membrane was tested normally (dense selective layer facing draw solution) and reversely (dense selective layer facing feed solution). Explanations on transport phenomenon in FO process were proposed which explain the observation that the FO membrane, when used in the normal orientation, performed better due to lesser internal concentration polarization. This study suggests that an ideal FO membrane should consist of a thin dense selective layer without any loose fabric support layer.
使用实验室规模的装置研究了正向（直接）渗透（FO）过程的性能，以阐明膜结构和取向对水通量的影响。使用两种反渗透（RO）膜和一种FO膜，以碳酸氢铵、葡萄糖和果糖作为汲取溶液，从含盐进料溶液中提取水。在相同实验条件下，FO膜能够实现比RO膜更高的水通量，同时保持大于97%的高脱盐率。提高操作温度会增加FO过程中的水通量。为了研究膜取向对水通量的影响，对FO膜进行了正向（致密选择层面向汲取溶液）和反向（致密选择层面向进料溶液）测试。对FO过程中的传输现象提出了解释，这些解释说明了以下观察结果：FO膜在正向使用时，由于内部浓差极化较小，性能更好。本研究表明，理想的FO膜应由无任何疏松织物支撑层的薄致密选择层组成。
