Amphoteric Ion Exchangers

Ion exchangers which contain both acidic and basic groups are called amphoteric resins. Usually their matrix has some structural units with acidic groups and other units with basic groups.

Very interesting amphoteric resins are the so-called 'snake-cage polyelectrolytes'. One feature distinguishes the snake-cage polyelectrolytes from other amphoteric resins, namely the acidic and basic groups are not attached to the same matrix. For example, a snake-cage polyelectrolyte is prepared by polymerization of acrylic acid (snake) into a strong base anion exchanger with quaternary ammonium groups (cage). These resins are excellent reversible sorbents for electrolytes and can be regenerated by rinsing with water. Electrolyte sorption seems to be mainly determined by the preference of the acidic groups for the cation and of the basic groups for the anion. The resins show preference for different electrolytes. This phenomenon can be used for separating electrolytes one from another.

Figure 12 Chemical structure of the functional groups which can exist in a polystyrene-based weak base anion exchanger.
Figure 13 Acrylic-type weak base anion exchangers and their preparation methods.

The snake-cage polyelectrolytes are also used in the technique of 'ion retardation'. This technique is the separation of strong electrolytes from weak electrolytes or non-electrolytes.

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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