Oxidation of 2,4-D using iron activated persulfate and peroxymonosulfate

This study reviews the application of sulfate free radicals for the oxidation of organic pollutants in surface water and groundwater. Sulfate free radicals can be generated from persulfate and peroxymonosulfate (PMS) using various activation methods. Activation methods include heat, transition metals, and ultra-violet light. Experiments were conducted to investigate the oxidation of 2,4-dichlorophenoxyacetic acid (2,4-D) by sulfate free radicals generated by the activation of persulfate anion or peroxymonosulfate using ferrous ions. 2,4-D was found to be rapidly oxidized within minutes but plateaued to a asymptotic concentration. The optimal molar ratio of persulfate:Fe2+ or peroxymonosulfate:Fe2+ for the oxidation of 2,4-D was found to be 1:1. The plateauing of 2,4-D concentration in the oxidation process may be due to the rapid conversion of Fe2+ to Fe3+ by the sulfate radicals generated which in turn slowed the activation process. Sequential addition of Fe2+ at different times resulted in further 2,4-D oxidation which indicates that Fe2+ may be limiting in the activation process. A bi-exponential first-order model provided the best fit of the experimental data with R2 values greater than 90%. Ferrous ion can be used as a low cost material to activate persulfate or peroxymonosulfate for the removal of 2,4-D and other organic compounds in contaminated groundwater and drinking water

Pervious Concrete Physical Characteristics and Effectiveness in Stormwater Pollution Reduction

The objective of this research was to investigate the physical/chemical and water flow characteristics of various previous concrete mixes made of different concrete materials and their effectiveness in attenuating water pollution. Four pervious concrete mixes were prepared with Portland cement and with 15% cementitious materials (slag, limestone powder, and fly ash) as a Portland cement replacement. All four pervious concrete mixtures had acceptable workability. The unit weight of the fresh pervious concrete mixtures ranged from 115.9 lb/yd3 to 119.6 lb/yd3 , while the 28 day compressive strength of the pervious concrete mixes ranged from 1858 psi (mix with 15% slag) to 2285 psi (pure cement mix). The compressive strength generally increased with unit weight and decreased with total porosity (air void ratio). The permeability of the four mixes generally decreased with unit weight and increased with total porosity. The permeability coefficients ranged from 340 in./hr for the pure cement mix to 642 in./hr for the mix with 15% slag. The total porosities of the four pervious concrete mixes ranged from 24.00% (mix with 15% slag) to 31.41% (pure cement mix) as measured by the flatbed scanner test method, while the porosities ranged from 18.93% (mix with 15% slag) to 24.15% (pure cement mix) as measured by the RapidAir method. The total porosities of the four pervious concrete mixes measured by the flatbed scanner method were higher than those measured by the Rapid Air method, but the specific surface areas measured by the flatbed scanner method were all lower than those measured by the Rapid Air method. For the pollution abatement experiments, mixes with fly ash and limestone powder removed about 30% of the input naphthalene concentration, while the mix with slag only removed 0.5% of the influent naphthalene concentration. The water volume balance showed that less than 1% of the water added was retained in the experimental column setup

Fly ash-based geopolymer as innovative material for environmental applications

Fly ash-based geopolymer were synthesized from Class-F fly ash and slag with an alkaline activating solution and characterized for their physical-chemical properties. The geopolymer samples were tested to investigate their environmental impacts when used for environmental applications. Batch adsorption studies were conducted using fly ash-based geopolymer as a reactive material or an adsorbent for heavy metals (Cu2+, Cd2+ and Pb2+). The removal capacities for Cu2+, Cd2+ and Pb2+ ranged from 20.66 – 35.21, 28.74 – 42.02, and 116.28 – 121.95 mg/g for initial pHs ranged from 2.5 to 4.0, respectively, at room temperatures of 21 – 23 oC. Fixed bed column studies were carried out using fly ash-based geopolymer as a filtration medium for removal of metal (Cu2+, Cd2+, and Pb2+) in low pH solutions. Breakthrough curves showed that the adsorption affinity of the geopolymer for metals was in the order of Pb2+ > Cd2+ > Cu2+ for a single metal solution and in the order of Pb2+ > Cu2+ > Cd2+ for a multi-metal solution which shows that there was a competition for adsorption sites on the geopolymer. The geopolymer can be used to neutralize the pH of acidic waste streams and at the same time adsorb or precipitate metal pollutants. In addition, magnetic geopolymers were synthesized by incorporating magnetic Fe3O4 particles to modify the fly ash-based geopolymer. Magnetic fly ash geopolymer showed similar adsorption properties as fly ash-based geopolymer with a maximum adsorption capacity of 111.1 mg/g. The magnetic fly ash geopolymer has a saturation magnetization of 18 emu/g and was found to separate out from an aqueous solution within 2 minutes by using a magnetic field of 0.48 Tesla. Applications of the magnetic fly ash geopolymer include using it as a powdered adsorbent to maximize heavy metals removal and recovery in wastewater treatment.</p

Oxidation of 2,4-D using iron activated persulfate and peroxymonosulfate

This study reviews the application of sulfate free radicals for the oxidation of organic pollutants in surface water and groundwater. Sulfate free radicals can be generated from persulfate and peroxymonosulfate (PMS) using various activation methods. Activation methods include heat, transition metals, and ultra-violet light. Experiments were conducted to investigate the oxidation of 2,4-dichlorophenoxyacetic acid (2,4-D) by sulfate free radicals generated by the activation of persulfate anion or peroxymonosulfate using ferrous ions. 2,4-D was found to be rapidly oxidized within minutes but plateaued to a asymptotic concentration. The optimal molar ratio of persulfate:Fe2+ or peroxymonosulfate:Fe2+ for the oxidation of 2,4-D was found to be 1:1. The plateauing of 2,4-D concentration in the oxidation process may be due to the rapid conversion of Fe2+ to Fe3+ by the sulfate radicals generated which in turn slowed the activation process. Sequential addition of Fe2+ at different times resulted in further 2,4-D oxidation which indicates that Fe2+ may be limiting in the activation process. A bi-exponential first-order model provided the best fit of the experimental data with R2 values greater than 90%. Ferrous ion can be used as a low cost material to activate persulfate or peroxymonosulfate for the removal of 2,4-D and other organic compounds in contaminated groundwater and drinking water.</p

Fly ash-based geopolymer as innovative material for environmental applications

Fly ash-based geopolymer were synthesized from Class-F fly ash and slag with an alkaline activating solution and characterized for their physical-chemical properties. The geopolymer samples were tested to investigate their environmental impacts when used for environmental applications. Batch adsorption studies were conducted using fly ash-based geopolymer as a reactive material or an adsorbent for heavy metals (Cu2+, Cd2+ and Pb2+). The removal capacities for Cu2+, Cd2+ and Pb2+ ranged from 20.66 – 35.21, 28.74 – 42.02, and 116.28 – 121.95 mg/g for initial pHs ranged from 2.5 to 4.0, respectively, at room temperatures of 21 – 23 oC. Fixed bed column studies were carried out using fly ash-based geopolymer as a filtration medium for removal of metal (Cu2+, Cd2+, and Pb2+) in low pH solutions. Breakthrough curves showed that the adsorption affinity of the geopolymer for metals was in the order of Pb2+ \u3e Cd2+ \u3e Cu2+ for a single metal solution and in the order of Pb2+ \u3e Cu2+ \u3e Cd2+ for a multi-metal solution which shows that there was a competition for adsorption sites on the geopolymer. The geopolymer can be used to neutralize the pH of acidic waste streams and at the same time adsorb or precipitate metal pollutants. In addition, magnetic geopolymers were synthesized by incorporating magnetic Fe3O4 particles to modify the fly ash-based geopolymer. Magnetic fly ash geopolymer showed similar adsorption properties as fly ash-based geopolymer with a maximum adsorption capacity of 111.1 mg/g. The magnetic fly ash geopolymer has a saturation magnetization of 18 emu/g and was found to separate out from an aqueous solution within 2 minutes by using a magnetic field of 0.48 Tesla. Applications of the magnetic fly ash geopolymer include using it as a powdered adsorbent to maximize heavy metals removal and recovery in wastewater treatment

Pervious Concrete Physical Characteristics and Effectiveness in Stormwater Pollution Reduction

The objective of this research was to investigate the physical/chemical and water flow characteristics of various previous concrete mixes made of different concrete materials and their effectiveness in attenuating water pollution. Four pervious concrete mixes were prepared with Portland cement and with 15% cementitious materials (slag, limestone powder, and fly ash) as a Portland cement replacement. All four pervious concrete mixtures had acceptable workability. The unit weight of the fresh pervious concrete mixtures ranged from 115.9 lb/yd3 to 119.6 lb/yd3 , while the 28 day compressive strength of the pervious concrete mixes ranged from 1858 psi (mix with 15% slag) to 2285 psi (pure cement mix). The compressive strength generally increased with unit weight and decreased with total porosity (air void ratio). The permeability of the four mixes generally decreased with unit weight and increased with total porosity. The permeability coefficients ranged from 340 in./hr for the pure cement mix to 642 in./hr for the mix with 15% slag. The total porosities of the four pervious concrete mixes ranged from 24.00% (mix with 15% slag) to 31.41% (pure cement mix) as measured by the flatbed scanner test method, while the porosities ranged from 18.93% (mix with 15% slag) to 24.15% (pure cement mix) as measured by the RapidAir method. The total porosities of the four pervious concrete mixes measured by the flatbed scanner method were higher than those measured by the Rapid Air method, but the specific surface areas measured by the flatbed scanner method were all lower than those measured by the Rapid Air method. For the pollution abatement experiments, mixes with fly ash and limestone powder removed about 30% of the input naphthalene concentration, while the mix with slag only removed 0.5% of the influent naphthalene concentration. The water volume balance showed that less than 1% of the water added was retained in the experimental column setup.For this and other reports please see the project pages at the Midwest Transportation Center http://intrans.iastate.edu/mtc/index.cfm/research/project/project/-688823950</p

Pervious Concrete Physical Characteristics and Effectiveness in Stormwater Pollution Reduction

The objective of this research was to investigate the physical/chemical and water flow characteristics of various previous concrete mixes made of different concrete materials and their effectiveness in attenuating water pollution. Four pervious concrete mixes were prepared with Portland cement and with 15% cementitious materials (slag, limestone powder, and fly ash) as a Portland cement replacement. All four pervious concrete mixtures had acceptable workability. The unit weight of the fresh pervious concrete mixtures ranged from 115.9 lb/yd3 to 119.6 lb/yd3 , while the 28 day compressive strength of the pervious concrete mixes ranged from 1858 psi (mix with 15% slag) to 2285 psi (pure cement mix). The compressive strength generally increased with unit weight and decreased with total porosity (air void ratio). The permeability of the four mixes generally decreased with unit weight and increased with total porosity. The permeability coefficients ranged from 340 in./hr for the pure cement mix to 642 in./hr for the mix with 15% slag. The total porosities of the four pervious concrete mixes ranged from 24.00% (mix with 15% slag) to 31.41% (pure cement mix) as measured by the flatbed scanner test method, while the porosities ranged from 18.93% (mix with 15% slag) to 24.15% (pure cement mix) as measured by the RapidAir method. The total porosities of the four pervious concrete mixes measured by the flatbed scanner method were higher than those measured by the Rapid Air method, but the specific surface areas measured by the flatbed scanner method were all lower than those measured by the Rapid Air method. For the pollution abatement experiments, mixes with fly ash and limestone powder removed about 30% of the input naphthalene concentration, while the mix with slag only removed 0.5% of the influent naphthalene concentration. The water volume balance showed that less than 1% of the water added was retained in the experimental column setup.For this and other reports please see the project pages at the Midwest Transportation Center http://intrans.iastate.edu/mtc/index.cfm/research/project/project/-688823950</p

Gene Editing of the Catfish Gonadotropin-Releasing Hormone Gene and Hormone Therapy to Control the Reproduction in Channel Catfish, <i>Ictalurus punctatus</i>

Transcription activator-like effector nuclease (TALEN) plasmids targeting the channel catfish gonadotropin-releasing hormone (cfGnRH) gene were delivered into fertilized eggs with double electroporation to sterilize channel catfish (Ictalurus punctatus). Targeted cfGnRH fish were sequenced and base deletion, substitution, and insertion were detected. The gene mutagenesis was achieved in 52.9% of P1 fish. P1 mutants (individuals with human-induced sequence changes at the cfGnRH locus) had lower spawning rates (20.0–50.0%) when there was no hormone therapy compared to the control pairs (66.7%) as well as having lower average egg hatch rates (2.0% versus 32.3–74.3%) except for one cfGnRH mutated female that had a 66.0% hatch rate. After low fertility was observed in 2016, application of luteinizing hormone-releasing hormone analog (LHRHa) hormone therapy resulted in good spawning and hatch rates for mutants in 2017, which were not significantly different from the controls (p > 0.05). No exogenous DNA fragments were detected in the genome of mutant P1 fish, indicating no integration of the plasmids. No obvious effects on other economically important traits were observed after the knockout of the reproductive gene in the P1 fish. Growth rates, survival, and appearance between mutant and control individuals were not different. While complete knock-out of reproductive output was not achieved, as these were mosaic P1 brood stock, gene editing of channel catfish for the reproductive confinement of gene-engineered, domestic, and invasive fish to prevent gene flow into the natural environment appears promising