Abstract: It is very important to take appropriate inhibiting scaling measurements in brackish water reverse osmosis(BWRO) desalination process, which depends on feed water characteristics and scaling formation mechanism on membrane surface. Managing scale formation relies on early scaling potential prediction, judicious system design, influent pretreatment and non-destructive detection. A range of conventional and emerging analytical techniques, including molar ratio, direct observation and spectroscopic methods have evolved to predict scale potential and detect scale formation in real time. This review considers the prediction of scaling tendency, scale control techniques and non-destructive scale monitoring techniques based scales that are encountered when reverse osmosis is used in brackish water desalination applications. These techniques can significantly inhibit membrane surface scaling and decrease membrane fouling. Moreover, the suggestions are also presented in this field. 相似文献
Application of ultrafiltration, nanofiltration, reverse osmosis, membrane distillation, and integrated membrane processes
for the preparation of process water from natural water or industrial effluents was investigated. A two-stage reverse osmosis
plant enabled almost complete removal of solutes from the feed water. High-purity water was prepared using the membrane distillation.
However, during this process a rapid membrane fouling and permeate flux decline was observed when the tap water was used as
a feed. The precipitation of deposit in the modules was limited by the separation of sparingly soluble salts from the feed
water in the nanofiltration. The combined reverse osmosis—membrane distillation process prevented the formation of salt deposits
on the membranes employed for the membrane distillation. Ultrafiltration was found to be very effective removing trace amounts
of oil from the feed water. Then the ultrafiltration permeate was used for feeding of the remaining membrane modules resulting
in the total removal of oil residue contamination. The ultrafiltration allowed producing process water directly from the industrial
effluents containing petroleum derivatives.
Presented at the 33rd International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 22–26 May
2006. 相似文献
Metal-organic frameworks (MOFs) are promising candidates for membrane-based liquid separations due to their intrinsic microporosity, but many are limited by their insufficient stability. In this work, a copper-benzoquinoid (Cu-THQ) MOF was synthesized and demonstrated structural stability in water and organic solvents. After incorporation into the polyamide layer, the hydrophilicity of the membranes was enhanced. The resultant thin-film nanocomposite (TFN) membranes broke the permeability-selectivity tradeoff by showing 242 % increase in water permeance and slightly enhanced salt rejection at MOF loading of 0.0192 mg cm−2. The underlying mechanism was probed by different chemical and morphological characterizations. The membranes also showed improved tolerance to chlorine oxidation. With their excellent stability, the Cu-THQ MOF-based membranes further demonstrated impressive performance in organic solvent nanofiltration involving dimethylformamide. 相似文献
We present a method to produce anti‐fouling reverse osmosis (RO) membranes that maintains the process and scalability of current RO membrane manufacturing. Utilizing perfluorophenyl azide (PFPA) photochemistry, commercial reverse osmosis membranes were dipped into an aqueous solution containing PFPA‐terminated poly(ethyleneglycol) species and then exposed to ultraviolet light under ambient conditions, a process that can easily be adapted to a roll‐to‐roll process. Successful covalent modification of commercial reverse osmosis membranes was confirmed with attenuated total reflectance infrared spectroscopy and contact angle measurements. By employing X‐ray photoelectron spectroscopy, it was determined that PFPAs undergo UV‐generated nitrene addition and bind to the membrane through an aziridine linkage. After modification with the PFPA‐PEG derivatives, the reverse osmosis membranes exhibit high fouling‐resistance.
In this study, molecular dynamics simulation is used to investigate the effects of water-based substitutional defects in zeolitic imidazolate frameworks (ZIF)-8 membranes on their reverse osmosis (RO) desalination performance. ZIF-8 unit cells containing up to three defect sites are used to construct the membranes. These substitutional defects can either be Zn defects or linker defects. The RO desalination performance of the membranes is assessed in terms of the water flux and ion rejection rate. The effects of defects on the interactions between the ZIF-8 membranes and NaCl are investigated and explained with respect to the radial distribution function (RDF) and ion density distribution. The results show that ion adsorption on the membranes occurs at either the nitrogen atoms or the defect sites. Complete NaCl rejection can be achieved by introducing defects to change the size of the pores. It has also been discovered that the presence of linker defects increases membrane hydrophilicity. Overall, molecular dynamics simulations have been used in this study to show that water-based substitutional defects in a ZIF-8 structure reduce the water flux and influence its hydrophilicity and ion adsorption performance, which is useful in predicting the type and number of defect sites per unit cell required for RO applications. Of the seven ZIF-8 structures tested, pristine ZIF-8 exhibits the best RO desalination performance. 相似文献
The demand for lithium will increase in the near future to 713,000 tonnes per year. Although lake brines contribute to 80% of the production, existing methods for purification of lithium from this source are expensive, slow, and inefficient. A novel electrochemical process with low energy consumption and the ability to increase the purity of a brine solution to close to 98% with a single‐stage galvanostatic cycle is presented. 相似文献
