Anion mediation of aluminium-catalysed degradation of paper

The use of aluminium salts in papermaking has been linked well for over a century with causing degradation of paper. This is because the typical salts used in papermaking hydrolyse to release acid, which is a known catalyst that promotes degradation of cellulose, reducing both its degree of polymerisation and intrinsic strength. However, data reported here show that simplistic statements about the acidity of aluminium salts hide an interesting and complicated chemistry. In particular the presence of anions capable of coordinating with aluminium in solution is shown to exert an overwhelming influence on degradation reactions catalysed by the metal. Furthermore, the work highlights potential ways of pacifying aluminium cations contained in paper, effectively reducing or eliminating the degradation reactions they promote.