Degradation and formation of wood odorant β-cyclocitral during permanganate oxidation

The effect of permanganate oxidation on the formation and degradation of wood odorant β-cyclocitral in water was investigated. Oxidation experiments were conducted for β-cyclocitral prepared from pure chemicals and extracted from Microcystis aeruginosa. The data were simulated with appropriate kinetic rate models. The formation and degradation of β-cyclocitral during the oxidation of β-carotene were also monitored and modeled. The degradation of β-cyclocitral prepared from pure chemicals followed second-order kinetics with a rate constant of 91.7±2.4M^-1s^-1, and that of the β-cyclocitral precursor, β-carotene, followed first-order kinetics with a rate constant of 0.0054±0.0004min^-1. During the oxidation of β-carotene, β-cyclocitral was produced. The formation and degradation can both be simulated by first-order kinetics with respect to β-carotene and β-cyclocitral concentrations, respectively. The degradation rate of β-cyclocitral produced from β-carotene was found to be much slower than that for β-cyclocitral obtained from pure chemicals, very likely due to a mass transfer limitation. The kinetic models were further employed to simulate the oxidation of β-cyclocitral in the presence of β-carotene and for β-cyclocitral extracted from M. aeruginosa, respectively. The models well predict/fit the experimental data, with rate constants similar to other experiments, indicating that the models may be used for simulating the formation and degradation of β-cyclocitral in water treatment systems.