Application of the orthogonal collocation method in evaluating the rate of reactions using thermogravimetric analysis data

Abstract

The orthogonal collocation method offers a solution to the challenge of noise in thermogravimetric analysis data, improving upon the differential methods like the Friedman isoconversional method. This new technique requires only a few data points for interpolation to recreate conversion-time or conversion-temperature curves, from which a smooth reaction rate curve can be derived by differentiating polynomials. Remarkably, this method demands fewer than 20 data points for a precise estimation of reaction rates in single step reactions. The method's validity is supported by both simulated and actual reactions. Users can implement this technique using provided Gnu Octave (a free alternative to MATLAB) codes. Furthermore, the activation energy results of experimental data obtained from the Freidman and orthogonal collocation methods were in good agreement with those evaluated from the integral Vyazovkin and Ortega methods.