Membrane Selectivity

Improving membrane selectivity is still an area of active research. In some applications such as desalination of water, progress has been made, and membranes have the required selectivity to compete with other processes such as distillation. The first reverse osmosis membranes had salt rejections of approximately 96-97% and could only produce potable water from low concentration brackish water feeds. The best current membranes have salt rejections of up to 99.7% and can produce potable water from sea-water. Further improvements in membrane selectivity are not required in this application.

In other applications, the low selectivity of membranes remains a problem. Ultrafiltration membranes, for example, cannot separate dissolved macromolecules, such as albumin (Mr 60 000) and y-globulin (Mr 150 000). Therefore, ultrafiltration is limited to the separation of very large molecules from very small ones, such as macromolecules from dissolved micro-ions. Selectivity problems also exist in electrodialysis, gas separation and pervaporation.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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