Membranebased Separation

Chromatographic separation techniques are well established and widely used, however they do have some limitations, especially in the scale-up of separation processes. For larger-scale separations, they are therefore often replaced by membrane-based techniques, since membranes can be used in continuous mode unlike the batch-wise operation in chromatog-raphy.

Polymeric membranes can be made specific for certain target molecules by molecular imprinting. Imprinted membranes have been prepared in different ways; they can be cast directly as a thin layer on a flat surface or between two surfaces, and may or may not contain a stabilizing matrix. Alternatively they can be prepared by a phase inversion precipitation technique. Although imprinted membranes have great potential for applications in separation, especially chiral separation (enantiomeric polishing), they have until now merely been used in model studies and as recognition elements in biomimetic sensors. As an example, molecularly imprinted polymer membranes have been shown to be capable of distinguishing between enantiomers or otherwise closely related molecules. Usually, such membranes facilitate the diffusion of the compound which was imprinted relative to other closely related molecules. Thus, a membrane imprinted with 9-ethyladenine showed faster transport of adenosine than of guanosine. In other applications, selective retention by the membrane of the compound which was imprinted has been observed. For example, chiral discrimination was possible for d,l-phenylalanine, with the passage of the imprinted enantiomer being retarded.

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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