Liquid filtration desalination

As the newest development of the liquid filtration family, nanofiltration (NF) is capable of retaining small molecules from 200 to 1000 Da, and multivalent ions. The main current applications of NF polymeric membranes are dealing with the production of drinking and process water, the sulphate removal of seawater or the desalination of cheese whey. Ceramic nanofilters were... 

Fernandez, J.F., Waterkanp, D. and Thoming, J., Recovery of ionic liquids from wastewater Aggregation control for intensified membrane filtration. Desalination 224, 52-56 (2008). 

The separation of suspensions is the selective removal of suspended solids, say, by the ordinary processes of filtration. Application can also made to the separation of colloidal suspensions of minute or microscopic solid particles, and even of emulsions, the suspension of minute immiscible liquid droplets within another liquid phase. A distinguishing feature of ordinary filtration is usually that the discharged liquid phase does not form a continuum on the downflow or reject side of the membrane, or filter, and more or less exists at atmospheric pressure. If otherwise, if a contiunuum is formed, the process is more that of reverse osmosis, also called hyperfiltration. In common use, notably for the upgrading or desalination of salt water or brackish water, reverse osmosis is a subject for special consideration. 

The application of FO in recent years has expanded, not only in terms of installed capacity but also in the diversity of industries where the technology has been installed. Applications such as power generation, desalination, wastewater treatment (osmotic membrane bioreactor) and liquid food concentration are reported in the literature [4]. Commercial FO products are available for a variety of applications including personal water filtration and desalination, oil gas drilling water reclamation and landfill leachate treatment. 

With their particular structure, CNTs have been the ideal test bed to directly investigate liquid behavior under confinement. Some of these findings are now being tested for applications, in particular in the area of water filtration and desalination. ... 

Below ultrafiltration in size terms come nanofiltration and reverse osmosis, which look just like filtration processes and are often counted in with them - they have a liquid flow, and a semi-permeable membrane is placed as a barrier across this flow. However, NF and RO differ from UF in operating principle the liquid treated is now a solution with no (or extremely little, if properly prefiltered) suspended matter. The membranes have no physical holes through them, but are capable of dissolving one or more small molecular species (such as water in the case of RO desalination) into the membrane material itself. These species diffuse through the membrane, under the high trans-membrane pressure, and emerge in their pure state on the other side. 

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