Assessment of the effect of pH values on the complexing ability of two etherified derivatives of chitosan with a view to improving retention of heavy metals into cement mortars

Abstract

Book of abstracts of the13th International Conference on Electroanalysis ESEAC, 2010; PIN50:358: Removal of heavy metals from polluted aqueous systems (industrial and waste waters) may be accomplished by complexing and sequestering them into inert matrices. A suitable matrix can be cement mortars, owing to the fact that they have the capability of immobilise and stabilise the complexes, reducing heavy metal leaching. The complexing ligand has to be properly chosen so that it presents high affinity for the metal and a good performance of the formed complex in the largely alkaline medium of the cement mortar. Our research interest is focused on chitosans and its derivatives as a model ligand that fulfills both demands. The complexing ability of unmodified chitosans for several target heavy metals has been checked in acetated buffer (pH = 4) [1]. In this contribution we will take advantage of the fact that some etherified chitosans are soluble in alkaline pH mimicking the cement mortar conditions. Retention of Zn and Pn in alkaline media by the etherified chitosans will be related to the heavy metal concentrations found in the leaching coming from polymer modified mortars.