Studies on application of enzymes in wastewater treatment for emerging contaminants have often focused on single-compound treatments. In the present study, Acetaminophen, methyl, propyl, and butyl parabens and their degradation intermediate, para-hydroxybenzoic acid were treated individually and then as an equimolar mixture of the five compounds (mix-5) in synthetic wastewater using partially purified soybean peroxidase, targeting a removal of 95% of starting concentration. Compound removals were monitored using HPLC. The reaction parameters (concentration of hydrogen peroxide, enzyme activity, and pH) were optimized for each compound and then as mix-5. Based on optimized parameters, reaction time courses were determined from which pseudo-first-order initial rate constants were calculated. Oligomers formed in each case were determined both in supernatants and precipitates, using high resolution-MS. In single treatment, normalized rate constants were in the order acetaminophen&gt;butyl paraben ≈ propyl paraben &gt; para-hydroxybenzoic acid ≈ methyl paraben, whereas in mix-5, the order was acetaminophen &gt; butyl paraben &gt; para-hydroxybenzoic acid &gt; propyl paraben ≈ methyl paraben. Determination of oligomers formed in single-compound treatment showed the presence of dimers of para-hydroxybenzoic acid, pentamers of acetaminophen, hexamers of propyl paraben and heptamers of methyl and butyl parabens. Mass spectral analysis of mix-5 showed the presence of homo- and hetero-oligomers of the compounds up to pentamers in precipitates and heptamers in supernatant. Mixture treatment improved the percentage removal of compounds which were poorly removed when treated alone. This demonstrates the possibility for scale-up trials for industrial wastewater treatment plants effluent such as those emanating from pharmaceutical manufacturing companies and others where toxic mixtures are poorly treated by conventional treatment processes.

Reaction kinetics and products characterization by LC-MS of five emerging contaminants in single- and mixed- treatments with soybean peroxidase for wastewater treatment

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.