Modelling the Kinetics of Elements Release from a Zeolitic-Rich Tuff

Abstract

The present investigation aims at modeling the kinetics of elements (Fe, Mg, K, Ca, Na, Al, and Si) release from zeolitic-rich Phlegraean Yellow Tuff weathered by tannic acid solutions at different concentration. Three equations were tested—power function, the Weber–Morris model, and the Elovich equation. Power function was revealed to be an excellent empirical equation well fitted to the experimental data. Its numerical parameters were suitable predictive tools, highlighting both the intensity and modality of weathering processes. By paralleling the dissolution rates, it was possible to allow rock-sources from which elements were released during three distinct weathering stages—(i) the first stage was dominated by biotite and amorphous weathering, (ii) the second stage also started with the breakdown of zeolite framework; and (iii) in the third stage, the whole of weathering/release process approached a steady state. Finally, these outcomes may be used to forecast the pedogenic/nutritional potential of zeolitic-rich tuffs as pedotechnical matrices in restoration design.