No abstract

Interest in using various nanoparticle catalysts to activate H2O2 with light for organic contaminant and wastewater treatment is steadily increasing. We successfully synthesized magnetically recoverable Cu0.5Mn0.5Fe2O4 nanoparticles using a simple co-precipitation method followed by melamine-assisted calcination. Material characterization revealed that melamine acted as a coordinating agent during the calcination process that promoted a ferrite structure. Copper (Cu)-substitution effectively decreased material aggregation and promoted catalytic activities. Cu0.5Mn0.5Fe2O4 nanoparticles showed outstanding catalytic performance on several organic contaminants (87.6–100.0% removal within 2 h). Using oxytetracycline (OTC) as a surrogate wastewater constituent, we found that the hydroxyl radical (•OH) and superoxide anions (•O2−) were the active radical species involved in OTC degradation. Cu0.5Mn0.5Fe2O4 nanoparticles exhibited excellent photo-Fenton catalytic ability in real wastewater and demonstrated high material stability, even after four consecutive uses (i.e., fourth cycle). In a pilot-scale experiment (10 L), we provide proof that our rigorous treatment system was able to remove remnant OTC, TOC, and also any available colloidal particles to only 1 NTU. Ecotoxicity studies using an aquatic plant (Hydrilla verticillata) and zooplankton revealed that treated water could be reused in various ratios. Furthermore, at 5% of treated water, rapid leaf recovery and a significant increase in rotifer numbers were reported. These observations support the use of Cu0.5Mn0.5Fe2O4/H2O2/light as an efficient and environmentally friendly catalytic system for treatment of organic contaminants, and a radical generating mechanism is proposed.

1. Global trade in non-native ornamental species coupled with high connectivity among countries is well known to result in worldwide biological invasions, which pose challenges for the conservation and management of biodiversity.2. There are few studies aimed at implementing management strategies that have examined differences in the potential invasiveness of non-native species between neighbouring political regions within the same ecoregion.3. To compare the potential risk of invasiveness of non-native ornamental fishes with high commercial value in the river basins of two neighbouring regions of East and Southeast Asia, 32 extant and horizon species were screened with the AQUATIC SPECIES INVASIVENESS SCREENING KIT (AS-ISK) for the lower Pearl River basin (South China) and the Chao Phraya River basin (Thailand). Both regional (i.e. basin level) and combined risk-ranking thresholds were determined by receiver operating characteristic curve analysis. 4. Of the 32 species screened, 14 were categorized as posing a high risk and seven were categorized as posing a medium risk of being invasive in both regions, under