Kinetic Model of CCA Fixation in Wood. Part II. The Main Reaction Zone

Authors

  • Feroz K. M. Kazi
  • Paul A. Cooper
  • Jianbin Chen

Keywords:

Preservative, CCA-C, wood, red pine (<i>Pinus resinosa</i> Ait.), fixation, main reaction, model, activation energy

Abstract

Fixation of chromated copper arsenate type C (CCA-C) solution on wood, measured by hexavalent chromium reduction, follows different rates in different reaction zones. We identify two main zones: an initial reaction and a second main reaction. The main reaction zone in red pine (Pinus resinosa Ait.) starts once approximately 47% of the total CrvI in the impregnated CCA-C solution is fixed on wood matrix. The second main fixation reaction follows first-order reaction kinetics, and an Arrhenius type of correlation can be used in modeling the fixation kinetics. We obtained similar values of Arrhenius parameters for CCA-C concentrations of 1% and 3%. The activation energies for fixation reactions in the second zone were 87.6 and 88.1 kJ/mol for 1% and 3% CCA-C concentrations, respectively. The pre-exponential factors of the reaction rate constant were 2.7 X 1013 and 2.2 X 1013 h-1 for 1 and 3% solutions, respectively. By combining the reaction rate equations and the temperature-dependence (Arrhenius) relationship, a mathematical model for the main reaction of 1% CCA-C fixation in red pine was produced.

This model estimates the percentage of CCA-C solution fixation on red pine for a given time (in hours)/temperature (K) history of the wood following treatment.

References

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Published

2007-06-19

Issue

Number 4 / October 2000

Section

Research Contributions

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