Adsorption of atmospheric carbonate and evolution of acidity during grinding of abnormal montmorillonite

Abstract

Montmorillonite (MMt) from Tunisia has been subjected to fine grinding and studied using FTIR spectroscopy, X-ray diffractograms, BET surface area, Brönsted and Lewis acidity analyse, and FTIR spectroscopy. As a result, significant changes in structural vibrations when MMt was mechanochemically treated were revealed. These changes include: a shift and a gradual decrease of structural OH, Si–O, and M–OH groups (M: octahedral cations; Al, Mg and Fe), which means that an imperfection was formed in the crystal mineral via a mechanochemical treatment. The grinding is associated with amelioration of the oxidative power of clay, which is manifested by the sharpening of the infrared absorption shoulder near 880 cm^–1. The thermo-FTIR adsorption of N-butylamine showed that acidity did not improve upon grinding. On the contrary, the mechanochemical treatment led to the creation of the basic sites which promote the adsorption of atmospheric dioxide carbon.