Application of Elovich Equation to the Kinetics of Phosphate Release and Sorption in Soils

TLDR

Experimental data on phosphate release and sorption in soils are often interpreted as a combination of two or three simultaneous first‑order reactions when a single first‑order kinetic model is inadequate. The study derived a simple modified Elovich equation to fit phosphate release and sorption data that could not be described by a single first‑order kinetic model. The modified Elovich equation \(q = \frac{1}{\beta}\ln(\alpha\beta) + \frac{1}{\beta}\ln t\) relates the amount of phosphate released or sorbed (q) to time, with α and β as constants. The equation described the data as a single straight line over the entire reaction time, and the constants α and β can be used to compare reaction rates across different soils.

Abstract

Abstract Experimental data on the phosphate release and sorption in soils, when inadequately described by a first‐order kinetic reaction, are often interpreted as a combination of two or three simultaneous first‐order reactions. A simple modified Elovich equation in the form: q = (1/β) ln (αβ) + (1/β) ln t was derived to fit the reported experimental data in literature that failed to conform to a single first‐order kinetic equation. In this equation, q is the amount of phosphate released or sorbed, and α and β are constants. The equation successfully described the data as a single straight line that covers the entire course of reaction time. It also appears that constants of α and β may be used for comparison of reaction rates of phosphate release or sorption in different soils.