Iron is rich in soils, and is recently reported to form stable complexes with organic free radicals, generating environmentally persistent free radicals (EPFRs). The observation may challenge the common viewpoint that iron is an effective catalyst to facilitate the degradation of various organic chemicals. But no study was specifically designed to investigate the possible inhibited degradation of organic chemicals because of the formation of EPFRs in dry environment. We observed that catechol degradation under UV irradiation was decreased over 20% in silica particles coated with 1% hematite in comparison to uncoated silica particles. Stabilized semiquinone or quinine and phenol radicals were involved in HMT-silica system. EPFR formation was thus the reason for the reduced catechol degradation on HMT-silica surface under UV irradiation at ambient temperature. EPFRs should be incorporated in the studies of organic contaminants geochemical behavior, and will be a new input in their environmental fate modeling.
It is estimated that over 700,000 tons of synthetic dyes are produced annually, 15% of which are emitted as effluents. These highly stable dyes enter the world water ecosystems and stay in the environment, and eventually cause adverse impacts to the environment. Current wastewater treatment methods, such as filtration, coagulation, and chemical oxidation, have sideeffects, including toxic residue formation, membrane fouling, bioaccumulation, and secondary pollutant formation . Given the issues mentioned, it is necessary to study how to improve the degradation of synthetic dye with a cost-effective and ecofriendly approach. Natural oxidation provides a greener option. Recently, Deuteromycetes fungus Myrothecium verrucaria G-1 ( M. verrucaria G-1) has shown great potential in producing high level of dye oxidase . This study aims to generate a dye oxidase hyperproducer, 3H6 from M. verrucaria G-1 by using atmospheric and room temperature plasma (ARTP) coupled with ultraviolet (UV) irradiation. This method increases oxidase production by nearly 106.15%. After a simple precipitation and dialysis, this mutant oxidase increases by 1.97-fold in a specific activity with dye degradation rates at 70% for Mmethylene blue (MB) and 85% for Congo red (CR). It is found that the genetic stability of 3H6 remains active for ten generations. The size of oxidase is 65 kDa, and optimum temperature for reaction is 30 °C with 4.5 pH. This study presents that the first combined mutagenesis approach by ARPT-UV on fungus species generates an impressive increment of acid dye oxidases production. As such, this method presents a cost-effective alternative to mitigate hazardous dye pollution.
危险品化学品经营许可证（带存储）