4 research outputs found
Developing a Slow-Release Permanganate Composite for Degrading Aquaculture Antibiotics
Copious use of antibiotics in aquaculture farming systems has resulted in surface water contamination in some countries. Our objective was to develop a slow-release oxidant that could be used in situ to reduce antibiotic concentrations in discharges from aquaculture lagoons. We accomplished this by generating a slow-release permanganate (SR-MnO4-) that was composed of a biodegradable wax and a phosphate-based dispersing agent. Sulfadimethoxine (SDM) and its synergistic antibiotics were used as representative surrogates. Kinetic experiments verified that the antibiotic-MnO4- reactions were first-order with respect to MnO4- and initial antibiotic concentration (second-order rates: 0.056–0.128 s-1 M-1). A series of batch experiments showed that solution pH, water matrices, and humic acids impacted SDM degradation efficiency. Degradation plateaus were observed in the presence of humic acids (\u3e20 mgL-1), which caused greater MnO2 production. A mixture of KMnO4/beeswax/paraffin (SRB) at a ratio of 11.5:4:1 (w/w) was better for biodegradability and the continual release of MnO4-, but MnO2 formation altered release patterns. Adding tetrapotassium pyrophosphate (TKPP) into the composite resulted in delaying MnO2 aggregation and increased SDM removal efficiency to 90% due to the increased oxidative sites on the MnO2 particle surface. The MnO4- release data fit the Siepmann–Peppas model over the long term (t \u3c 48 d) while a Higuchi model provided a better fit for shorter timeframes (t \u3c 8 d). Our flow-through discharge tank system using SRB with TKPP continually reduced the SDM concentration in both DI water and lagoon wastewater. These results support SRB with TKPP as an effective composite for treating antibiotic residues in aquaculture discharge water
Dual Activation of Peroxymonosulfate Using MnFe\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e4\u3c/sub\u3e/g‑C\u3csub\u3e3\u3c/sub\u3eN\u3csub\u3e4\u3c/sub\u3e and Visible Light for the Efficient Degradation of Steroid Hormones: Performance, Mechanisms, and Environmental Impacts
Single activation of peroxymonosulfate (PMS) in a homogeneous system is sometimes insufficient for producing reactive oxygen species (ROS) for water treatment applications. In this work, manganese spinel ferrite and graphitic carbon nitride (MnFe2O4/g-C3N4; MnF) were successfully used as an activator for PMS under visible light irradiation to remove the four-mostdetected- hormone-contaminated water under different environmental conditions. The incorporation of g-C3N4 in the nanocomposites led to material enhancements, including increased crystallinity, reduced particle agglomeration, amplified magnetism, improved recyclability, and increased active surface area, thereby facilitating the PMS activation and electron transfer processes. The dominant active radical species included singlet oxygen (1O2) and superoxide anions (O2 •−), which were more susceptible to the estrogen molecular structure than testosterone due to the higher electron-rich moieties. The self-scavenging effect occurred at high PMS concentrations, whereas elevated constituent ion concentrations can be both inhibitors and promoters due to the generation of secondary radicals. The MnF/PMS/vis system degradation byproducts and possible pathways of 17β-estradiol and 17α-methyltestosterone were identified. The impact of hormone-treated water on Oryza sativa L. seed germination, shoot length, and root length was found to be lower than that of untreated water. However, the viability of both ELT3 and Sertoli TM4 cells was affected only at higher water compositions. Our results confirmed that MnF and visible light could be potential PMS activators due to their superior degradation performance and ability to produce safer treated water
Developing a Slow-Release Permanganate Composite for Degrading Aquaculture Antibiotics
Copious use of antibiotics in aquaculture farming systems has resulted in surface water contamination in some countries. Our objective was to develop a slow-release oxidant that could be used in situ to reduce antibiotic concentrations in discharges from aquaculture lagoons. We accomplished this by generating a slow-release permanganate (SR-MnO4−) that was composed of a biodegradable wax and a phosphate-based dispersing agent. Sulfadimethoxine (SDM) and its synergistic antibiotics were used as representative surrogates. Kinetic experiments verified that the antibiotic-MnO4− reactions were first-order with respect to MnO4− and initial antibiotic concentration (second-order rates: 0.056–0.128 s−1 M−1). A series of batch experiments showed that solution pH, water matrices, and humic acids impacted SDM degradation efficiency. Degradation plateaus were observed in the presence of humic acids (>20 mgL−1), which caused greater MnO2 production. A mixture of KMnO4/beeswax/paraffin (SRB) at a ratio of 11.5:4:1 (w/w) was better for biodegradability and the continual release of MnO4−, but MnO2 formation altered release patterns. Adding tetrapotassium pyrophosphate (TKPP) into the composite resulted in delaying MnO2 aggregation and increased SDM removal efficiency to 90% due to the increased oxidative sites on the MnO2 particle surface. The MnO4− release data fit the Siepmann–Peppas model over the long term (t < 48 d) while a Higuchi model provided a better fit for shorter timeframes (t < 8 d). Our flow-through discharge tank system using SRB with TKPP continually reduced the SDM concentration in both DI water and lagoon wastewater. These results support SRB with TKPP as an effective composite for treating antibiotic residues in aquaculture discharge water
Dual Activation of Peroxymonosulfate Using MnFe<sub>2</sub>O<sub>4</sub>/g‑C<sub>3</sub>N<sub>4</sub> and Visible Light for the Efficient Degradation of Steroid Hormones: Performance, Mechanisms, and Environmental Impacts
Single activation
of peroxymonosulfate (PMS) in a homogeneous
system
is sometimes insufficient for producing reactive oxygen species (ROS)
for water treatment applications. In this work, manganese spinel ferrite
and graphitic carbon nitride (MnFe2O4/g-C3N4; MnF) were successfully used as an activator
for PMS under visible light irradiation to remove the four-most-detected-hormone-contaminated
water under different environmental conditions. The incorporation
of g-C3N4 in the nanocomposites led to material
enhancements, including increased crystallinity, reduced particle
agglomeration, amplified magnetism, improved recyclability, and increased
active surface area, thereby facilitating the PMS activation and electron
transfer processes. The dominant active radical species included singlet
oxygen (1O2) and superoxide anions (O2•–), which were more susceptible to the
estrogen molecular structure than testosterone due to the higher electron-rich
moieties. The self-scavenging effect occurred at high PMS concentrations,
whereas elevated constituent ion concentrations can be both inhibitors
and promoters due to the generation of secondary radicals. The MnF/PMS/vis
system degradation byproducts and possible pathways of 17β-estradiol
and 17α-methyltestosterone were identified. The impact of hormone-treated
water on Oryza sativa L. seed germination,
shoot length, and root length was found to be lower than that of untreated
water. However, the viability of both ELT3 and Sertoli TM4 cells was
affected only at higher water compositions. Our results confirmed
that MnF and visible light could be potential PMS activators due to
their superior degradation performance and ability to produce safer
treated water