scholarly journals Oxidative Treatments of Pesticides in Rainwater Runoff by HOCl, O3, and O3/H2O2: Effects of pH, Humic Acids and Inorganic Matters

Separations ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 101
Author(s):  
Duuriimaa Ochir ◽  
Yonggu Lee ◽  
Jaegwan Shin ◽  
Sangwon Kim ◽  
Jinwoo Kwak ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Removal Efficiency ◽  
Reaction Times ◽  
Solution Ph ◽  
Pesticide Degradation ◽  
Oxidative Treatment ◽  
Treatment Processes ◽  
Effects Of Ph ◽  
Rainwater Runoff ◽  
Ph Conditions

This study systematically investigated the oxidative treatment of five selected pesticides, alachlor (ALA), carbendazim (CAR), diuron (DIU), pyrimethanil (PYR), and tebuconazole (TEB), by comparing their relative reactivities as a function of three different oxidative treatment processes (i.e., chlorine (HOCl), ozone (O3), and ozone/hydrogen peroxide (O3/H2O2)) under various oxidant dosages, reaction times, and pH conditions. For oxidative treatment, pesticide standards were spiked into rainwater. The removal efficiency of the selected pesticides varied considerably depending on the oxidative treatment processes. HOCl, O3, and O3/H2O2 treatments were highly effective at eliminating CAR (>80%) and PYR (>99%), while they were not significantly effective in removing TEB (<20%). In the case of DIU, HOCl (81%) was shown to be more effective than O3 (24%) and O3/H2O2 (49%). The removal efficiency of ALA was in the order of O3/H2O2 (49%) > O3 (20%) > HOCl (8.5%). The effect of increasing the solution pH from 5.0 to 9.0 on pesticide degradation varied between the oxidative treatment processes. Additionally, NH4+, NO2−, and humic acid in rainwater significantly inhibited pesticide degradation.

scholarly journals Removal of Polyvinyl Alcohol Using Photoelectrochemical Oxidation Processes Based on Hydrogen Peroxide Electrogeneration

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Kai-Yu Huang ◽  
Chih-Ta Wang ◽  
Wei-Lung Chou ◽  
Chi-Min Shu
Keyword(s):  
Hydrogen Peroxide ◽  
Light Intensity ◽  
Removal Efficiency ◽  
Flow Rate ◽  
Current Density ◽  
Uv Light ◽  
Supporting Electrolyte ◽  
Oxygen Flow Rate ◽  
Oxygen Flow ◽  
Solution Ph

This study investigates the removal efficiency of PVA from aqueous solutions using UV irradiation in combination with the production of electrogenerated hydrogen peroxide (H2O2) at a polyacrylonitrile-based activated carbon fiber (ACF) cathode. Three cathode materials (i.e., platinum, graphite, and ACF) were fed with oxygen and used for the electrogeneration of H2O2. The amount of electrogenerated H2O2produced using the ACF cathode was five times greater than that generated using the graphite cathode and nearly 24 times greater than that from platinum cathode. Several parameters were evaluated to characterize the H2O2electrogeneration, such as current density, oxygen flow rate, solution pH, and the supporting electrolyte used. The optimum current density, oxygen flow rate, solution pH, and supporting electrolyte composition were found to be 10 mA cm−2, 500 cm3 min−1, pH 3, and Na2SO4, respectively. The PVA removal efficiencies were achieved under these conditions 3%, 16%, and 86% using UV, H2O2electrogeneration, and UV/H2O2electrogeneration, respectively. A UV light intensity of 0.6 mW cm−2was found to produce optimal PVA removal efficiency in the present study. A simple kinetic model was proposed which confirmed pseudo-first-order reaction. Reaction rate constant (kap) was found to depend on the UV light intensity.

Enhanced decomposition of 1,4-dioxane in water by ozonation under alkaline condition

2014 ◽  
Vol 70 (12) ◽  
pp. 1934-1940 ◽  
Author(s):  
Gui-Peng Tian ◽  
Qian-Yuan Wu ◽  
Ang Li ◽  
Wen-Long Wang ◽  
Hong-Ying Hu
Keyword(s):  
Removal Efficiency ◽  
Kinetic Constant ◽  
Alkaline Condition ◽  
Aquatic Environments ◽  
Pseudo First Order Reaction ◽  
Oxidative Potential ◽  
First Order ◽  
Treatment Processes ◽  
Ph Conditions ◽  
Ph Range

1,4-Dioxane is a probable human carcinogenic and refractory substance that is widely detected in aquatic environments. Traditional wastewater treatment processes, including activated sludge, cannot remove 1,4-dioxane. Removing 1,4-dioxane with a reaction kinetic constant of 0.32 L/(mol·s) by using ozone, a strong oxidant, is difficult. However, under alkaline environment, ozone generates a hydroxyl radical (•OH) that exhibits strong oxidative potential. Thus, the ozonation of 1,4-dioxane in water under different pH conditions was investigated in this study. In neutral solution, with an inlet ozone feed rate of 0.19 mmol/(L·min), the removal efficiency of 1,4-dioxane was 7.6% at 0.5 h, whereas that in alkaline solution was higher (16.3–94.5%) within a pH range of 9–12. However, the removal efficiency of dissolved organic carbon was considerably lower than that of 1,4-dioxane. This result indicates that several persistent intermediates were generated during 1,4-dioxane ozonation. The pseudo first-order reaction further depicted the reaction of 1,4-dioxane. The obvious kinetic constants (kobs) at pH 9, 10, 11 and 12 were 0.94, 2.41, 24.88 and 2610 L/(mol·s), respectively. Scavenger experiments on radical species indicated that •OH played a key role in removing 1,4-dioxane during ozonation under alkaline condition.

Removal of sulphite-reducing clostridia spores by full-scale water treatment processes as a surrogate for protozoan (oo)cysts removal

2000 ◽  
Vol 41 (7) ◽  
pp. 165-171 ◽  
Author(s):  
W. A. Hijnen ◽  
J. Willemsen-Zwaagstra ◽  
P. Hiemstra ◽  
G. J. Medema ◽  
D. van der Kooij
Keyword(s):  
Water Treatment ◽  
Removal Efficiency ◽  
Water Quality Monitoring ◽  
Full Scale ◽  
Process Conditions ◽  
Safe Drinking Water ◽  
Unit Process ◽  
Treatment Processes ◽  
Scale Unit ◽  
Micro Organisms

At eight full-scale water treatment plants in the Netherlands the removal of spores of sulphite-reducing clostridia (SSRC) was determined. By sampling and processing large volumes of water (1 up to 500 litres) SSRC were detected after each stage of the treatment. This enabled the assessment of the removal efficiency of the full-scale unit processes for persistent micro-organisms. A comparison with literature data on the removal of Cryptosporidium and Giardia by the same type of processes revealed that SSRC can be considered as a potential surrogate. The average Decimal Elimination Capacity (DEC) of the overall treatment plants ranged from 1.3–4.3 log. The observed actual log removal of SSRC by the unit processes and the overall treatment at one of the studied locations showed that the level of variation in removal efficiency was approximately 2 log. Moreover, from the actual log removal values it was observed that a low SSRC removal by one unit process is partly compensated by a higher removal by subsequent unit processes at this location. SSRC can be used for identification of the process conditions that cause variation in micro-organism removal which may lead to process optimization. Further research is necessary to determine the optimal use of SSRC in water quality monitoring for the production of microbiologically safe drinking water.

Heterogeneous Fenton Catalytic Removal of Organic Pollutant in Aqueous Solution by using Coal Gangue as a Catalyst

2019 ◽  
Vol 12 (4) ◽  
pp. 312-325
Author(s):  
Jiwei Zhang ◽  
Jingjing Xu ◽  
Shuaixia Liu ◽  
Baoxiang Gu ◽  
Feng Chen ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Hydroxyl Radical ◽  
Removal Rate ◽  
Organic Pollutant ◽  
Coal Gangue ◽  
Ion Leakage ◽  
Heterogeneous Fenton ◽  
Solution Ph ◽  
X Ray

Background: Coal gangue was used as a catalyst in heterogeneous Fenton process for the degradation of azo dye and phenol. The influencing factors, such as solution pH gangue concentration and hydrogen peroxide dosage were investigated, and the reaction mechanism between coal gangue and hydrogen peroxide was also discussed. Methods: Experimental results showed that coal gangue has the ability to activate hydrogen peroxide to degrade environmental pollutants in aqueous solution. Under optimal conditions, after 60 minutes of treatment, more than 90.57% of reactive red dye was removed, and the removal efficiency of Chemical Oxygen Demand (COD) up to 72.83%. Results: Both hydroxyl radical and superoxide radical anion participated in the degradation of organic pollutant but hydroxyl radical predominated. Stability tests for coal gangue were also carried out via the continuous degradation experiment and ion leakage analysis. After five times continuous degradation, dye removal rate decreased slightly and the leached Fe was still at very low level (2.24-3.02 mg L-1). The results of Scanning Electron Microscope (SEM), energy dispersive X-Ray Spectrometer (EDS) and X-Ray Powder Diffraction (XRD) indicated that coal gangue catalyst is stable after five times continuous reuse. Conclusion: The progress in this research suggested that coal gangue is a potential nature catalyst for the efficient degradation of organic pollutant in water and wastewater via the Fenton reaction.

scholarly journals Efficient removal of arsenic from water by dielectrophoresis-assisted adsorption

2018 ◽  
Vol 19 (4) ◽  
pp. 1066-1072
Author(s):  
Q. H. Jin ◽  
C. Y. Cui ◽  
H. Y. Chen ◽  
Y. Wang ◽  
J. F. Geng ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Removal Efficiency ◽  
Solution Ph ◽  
Residual Concentration ◽  
Initial Concentration ◽  
Weight Percentage ◽  
Before And After ◽  
High Concentrations ◽  
Plant Ash ◽  
Adsorbent Dose

Abstract Adsorption (ADS) and dielectrophoresis (DEP) techniques were combined (ADS/DEP) to efficiently remove As(V) in industrial wastewater. Fly ash, activated carbon, corncob and plant ash were tested to determine the best adsorbent by their adsorption capacity. Plant ash showed the highest adsorption capacity compared with the others. Different parameters such as solution pH and adsorbent dose were explored. The maximum As(V) removal efficiency was 91.4% at the optimized conditions (pH 9.0, adsorbent dose 5 g/L) when the initial concentration of As(V) was 15 mg/L. With the ADS/DEP technique, the plant ash particles with adsorbed As(V) were trapped on the electrodes in a DEP device. The ADS/DEP process could increase the removal efficiency of As(V) to 94.7% at 14 V even when the initial concentration of As(V) was 15 mg/L. And the residual concentration of As(V) decreased to 0.34 mg/L after two series of the ADS/DEP process. The adsorbents before and after DEP were examined by scanning electron microscope (SEM) and energy dispersive X-ray (EDX) analysis. After the DEP process, the weight percentage of As(V) on the adsorbent surface increased to 0.96% from 0.5%. The ADS/DEP process could be a new efficient way to remove arsenic pollutant at high concentrations.

Impacts of Changing Operational Parameters of In Situ Chemical Oxidation (ISCO) on Removal of Aged PAHs from Soil

2012 ◽  
Vol 15 (2) ◽  
Author(s):  
Paula Cajal-Mariñosa ◽  
Ruth G. de la Calle ◽  
F. Javier Rivas ◽  
Tuula Tuhkanen
Keyword(s):  
Hydrogen Peroxide ◽  
Removal Efficiency ◽  
Contaminated Soil ◽  
Chemical Oxidation ◽  
Contaminant Removal ◽  
Operational Parameters ◽  
In Situ Chemical Oxidation ◽  
Different Types ◽  
Wood Impregnation

AbstractThe removal efficiency of two different types of peroxide addition, catalyzed hydrogen peroxide (CHP) and sodium percarbonate (SPC) were compared on a highly PAH-contaminated soil from a wood impregnation site. In an attempt to simulate real in situ reagents delivery, experiments have been carried out in acrylic columns. The main parameters affecting contaminant removal were the reagent’s temperature and the total addition of peroxide (g

scholarly journals Quaternization of Poly(2-diethyl aminoethyl methacrylate) Brush-Grafted Magnetic Mesoporous Nanoparticles Using 2-Iodoethanol for Removing Anionic Dyes

2021 ◽  
Vol 11 (21) ◽  
pp. 10451
Author(s):  
Khalid Mohammed Alotaibi ◽  
Abdurrahman A. Almethen ◽  
Abeer M. Beagan ◽  
Hassan M. Al-Swaidan ◽  
Ashfaq Ahmad ◽  
...  
Keyword(s):  
Mesoporous Silica Nanoparticles ◽  
High Surface ◽  
High Surface Area ◽  
Polymer Chains ◽  
Sunset Yellow ◽  
Anionic Dyes ◽  
Solution Ph ◽  
Effects Of Ph ◽  
Weak Adsorption ◽  
Ph Level

Magnetic mesoporous silica nanoparticles (Fe3O4-MSNs) were successfully synthesized with a relatively high surface area of 568 m2g−1. Fe3O4-MSNs were then modified with poly(2-diethyl aminoethyl methacrylate) (PDEAEMA) brushes using surface-initiated ARGET atom transfer radical polymerization (ATRP) (Fe3O4@MSN-PDMAEMA). Since the charge of PDEAEMA is externally regulated by solution pH, tertiary amines in the polymer chains were quaternized using 2-iodoethanol to obtain cationic polymer chains with a permanent positive charge (Fe3O4@MSN-QPDMAEMA). The intensity of the C−O peak in the C1s X-ray photoelectron spectrum increased after reaction with 2-iodoethanol, suggesting that the quaternization process was successful. The applicability of the synthesized materials on the removal of methyl orange (MO), and sunset yellow (E110) dyes from an aqueous solution was examined. The effects of pH, contact time, and initial dyes concentrations on the removal performance were investigated by batch experiments. The results showed that the Fe3O4@MSN-PDMAEMA sample exhibited a weak adsorption performance toward both MO and E110, compared with Fe3O4@MSN-QPDMAEMA at a pH level above 5. The maximum adsorption capacities of MO and E110 using Fe3O4@MSN-QPDMAEMA were 294 mg g−1 and 194.8 mg g−1, respectively.

scholarly journals Electrochemical oxidation of sulfamethoxazole using Ti/SnO2-Sb/Co-PbO2 electrode through ANN-PSO

2019 ◽  
Vol 84 (7) ◽  
pp. 713-727 ◽  
Author(s):  
Jiteng Wan ◽  
Chunji Jin ◽  
Banghai Liu ◽  
Zonglian She ◽  
Mengchun Gao ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Electrochemical Oxidation ◽  
Removal Efficiency ◽  
Current Density ◽  
Ph Value ◽  
Ann Model ◽  
Solution Ph ◽  
Pbo2 Electrode ◽  
Artificial Neural Network Ann ◽  
Major Factors

Even in a trace amounts, the presence of antibiotics in aqueous solution is getting more and more attention. Accordingly, appropriate technologies are needed to efficiently remove these compounds from aqueous environments. In this study, we have examined the electrochemical oxidation (EO) of sulfamethoxazole (SMX) on a Co modified PbO2 electrode. The process of EO of SMX in aqueous solution followed the pseudo-first-order kinetics, and the removal efficiency of SMX reached the maximum value of 95.1 % within 60 min. The effects of major factors on SMX oxidation kinetics were studied in detail by single-factor experiments, namely current density (1?20 mA cm-2), solution pH value (2?10), initial concentration of SMX (10?500 mg L-1) and concentration of electrolytes (0.05?0.4 mol L-1). An artificial neural network (ANN) model was used to simulate this EO process. Based on the obtained model, particle swarm optimization (PSO) was used to optimize the operating parameters. The maximum removal efficiency of SMX was obtained at the optimized conditions (e.g., current density of 12.37 mA cm-2, initial pH value of 4.78, initial SMX concentration of 74.45 mg L-1, electrolyte concentration of 0.24 mol L-1 and electrolysis time of 51.49 min). The validation results indicated that this method can ideally be used to optimize the related parameters and predict the anticipated results with acceptable accuracy.

scholarly journals Adsorption of Lysozyme Into a Charged Confining Pore

2021 ◽  
Author(s):  
Sidney Carvalho ◽  
Ralf Metzler ◽  
Andrey Cherstvy ◽  
Daniel Caetano
Keyword(s):  
Electrostatic Interactions ◽  
Active Sites ◽  
Coarse Grained ◽  
Pore Surface ◽  
Solution Ph ◽  
Coarse Grained Model ◽  
Egg White Lysozyme ◽  
Constant Ph ◽  
Pka Shift ◽  
Effects Of Ph

Several applications arise from the confinement of proteins on surfaces since their stability and biological activity are enhanced. It is also known that the way a protein adsorbs on the surface is important for its biological function since its active sites should not be obstructed. In this study, the adsorption properties of hen egg-white Lysozyme, HEWL, into a negatively charged silica pore is examined employing a coarse-grained model and constant-pH Monte Carlo simulations. The role of electrostatic interactions is taken into account when including the Debye-Hueckel potentials into the Ca structure-based model. We evaluate the effects of pH, salt concentration, and pore radius on the protein preferential orientation and spatial distribution of its residues regarding the pore surface. By mapping the residues that stay closer to the pore surface, we find the increase of pH leads to orientational changes of the adsorbed protein when the solution pH gets closer to the HEWL isoelectric point. At these conditions, the pKa shift of these important residues caused by the adsorption into the charged confining surface results in a HEWL charge distribution that stabilizes the adsorption in the observed protein orientation. We compare our observations to the results of pKa shift for HEWL available in the literature and to some experimental data.

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