Learning outcomes

After studying this course, you should be able to:

• understand that in drinking water anions have a beneficial range of concentration above which they may have an adverse effect on either human health or the environment. Toxic elements and compounds often block essential biological processes

• explain how excess anions or cations in aqueous solution can be removed by ion-exchange chromatography or an ion-exchange membrane

• explain how cations such as aluminium can be amphoteric, that is they can neutralise both acidic and alkaline solutions. Also recognise how this enables aluminium(III) ions to be used in water treatment.