Experimental and DFT simulation studies on the mechanism of acid and alkali promoted dissolution of albite

The mechanism of inorganic acid and alkali promoted weathering of albite is still unclear. In this work, the mechanism was investigated through leaching experiments and DFT simulations. The results showed that the leaching effect of albite was sorted as follows: hydrochloric acid > potassium hydroxide > deionized water. The H3O+ dehydrogenated by breakage of O-H bond, and then the proton bonded with the O atom to form a silicon hydroxyl group on the surface of albite. The O atom in OH- bonded with the three-coordinated Al atom to form the four-coordinated Al. The H2O molecule was adsorbed on the surface of albite by hydrogen bond. Meanwhile, the adsorption of H3O+, OH- and H2O on the (0 0 1) surface of albite caused the elongation of Si-O and Al-O bonds in the bulk phase, resulting in the loose framework of albite. Compared to the interaction mode of water molecules and albite, the H+ in hydrochloric acid and K+ in potassium hydroxide exchanged with Na+ in albite, which caused that the albite lattice was contracted and expanded, respectively. As a result, the surface of albite was damaged, and further caused the Na element was released from the albite crystal to liquid phase.

Automated summary

The mechanism of inorganic acid and alkali promoted weathering of albite was investigated through leaching experiments and DFT simulations in this study. The leaching effect of albite was found to be strongest with hydrochloric acid, followed by potassium hydroxide and deionized water. The interactions of acid and alkali with albite caused contraction and expansion of the albite lattice, resulting in its surface damage and release of sodium element.