How Green is Your Plasticizer?

Plasticizers are additives that are used to impart flexibility to polymer blends and improve their processability. Plasticizers are typically not covalently bound to the polymers, allowing them to leach out over time, which results in human exposure and environmental contamination. Phthalates, in particular, have been the subject of increasing concern due to their established ubiquity in the environment and their suspected negative health effects, including endocrine disrupting and anti-androgenic effects.

Risks associated with the environmental release of pharmaceuticals on the U.S. Food and Drug Administration "flush list".

A select few prescription drugs can be especially harmful and, in some cases, fatal with just one dose when not used as prescribed. Therefore, the U. S.

A comprehensive kinetic model of laccase-catalyzed oxidation of aqueous phenol.

A comprehensive model was developed to describe the kinetics of the laccase-catalyzed oxidation of phenol that incorporates enzyme kinetics, enzyme inactivation, variable reaction stoichiometry between substrate and oxygen, and oxygen mass-transfer. The model was calibrated and validated against data obtained from experiments conducted in an open system, which allowed oxygen to transfer from air to the reacting mixture and phenol conversion to approach completion. Inactivation of laccase was observed over the course of the reaction and was found to be dependent on the rate of substrate transformation.

Characterization of Trametes versicolor laccase for the transformation of aqueous phenol.

Laccase (oxygen oxidoreductase, EC 1.10.3.

Biocatalytic oxidation of bisphenol A in a reverse micelle system using horseradish peroxidase.

Horseradish peroxidase (HRP) was used to catalyze the oxidation of bisphenol A (BPA) in a reverse micelle system consisting of water, sodium bis(2-ethylhexyl)sulfosuccinate (AOT) as the surfactant, and n-octane as the organic solvent phase. In order to achieve maximal BPA transformation, a water-to-surfactant molar ratio greater than 15 was required, above which no further increase in conversion was observed. BPA transformation was catalyzed in the reverse micelle system over a pH range of 6-9 with an optimum at pH 7 and was enhanced with increasing temperatures up to 40 degrees C.

Variable stoichiometry during the laccase-catalyzed oxidation of aqueous phenol.

The oxidation of aqueous phenol through the catalytic action of laccase from Trametes versicolor was studied over a wide range of phenol concentrations and enzyme activities. The stoichiometric ratio, which is defined as the molar ratio of phenol transformed to oxygen consumed in the catalytic reaction, was found to increase with phenol concentration in the reaction mixture from a theoretical lower limit of 1 and to approach a theoretical upper limit of 4. A logistic equation was proposed to relate reaction stoichiometry to substrate concentration and was successfully used to relate these parameters over a range of phenol concentrations extending from approximately 0.

Impact of reaction conditions on the laccase-catalyzed conversion of bisphenol A.

The oxidative conversion of aqueous BPA catalyzed by laccase from Trametes versicolor was conducted in a closed, temperature-controlled system containing buffer for pH control. The effects of medium pH, buffer concentration, temperature and mediators and the impacts of dissolved wastewater constituents on BPA conversion were investigated. The optimal pH for BPA conversion was approximately 5, with greater than half maximal conversion and good enzyme stability in the range of 4-7.

Kinetic model of laccase-catalyzed oxidation of aqueous phenol.

Laccase from Trametes versicolor (EC 1.10.3.

Detoxification of phenolic solutions with horseradish peroxidase and hydrogen peroxide.

Phenolic solutions were treated with hydrogen peroxide and horseradish peroxidase (HRP) resulting in more than 95% removal of phenols within 3 h. Toxic compounds were formed during the treatment of aqueous solutions of phenol, 2-chlorophenol, 4-chlorophenol, 2,4-dichlorophenol and 2-methylphenol. However, the toxicities of HRP-treated solutions decreased within 21 h after the completion of the enzymatic reaction, except in the case of 2-methylphenol.