scholarly journals Preparation, Characterization, and Sludge Conditioning of Cationic Polyacrylamide Synthesized by a Novel UV-Initiated System

2018 ◽  
Author(s):  
Qingqing Guan ◽  
Guocheng Zhu ◽  
Yi Liao ◽  
Jin Xu ◽  
Xiaoxu Sun ◽  
...  
Keyword(s):  
Light Intensity ◽  
Intrinsic Viscosity ◽  
Uv Light ◽  
Proton Nuclear Magnetic Resonance ◽  
Initiator Concentration ◽  
Floc Size ◽  
Cationic Polyacrylamide ◽  
Sedimentation Behavior ◽  
Redox Initiator ◽  
Sludge Conditioning

Controlling the concentration of free radicals in polymerization systems is advantageous for preparing cationic polyacrylamide (CPAM) with high molecular weight and acceptable dissolvability. In this study, a novel ultraviolet (UV)-initiated system characterized with adjustable light intensity and redox-azo complex initiator was used to synthesize a CPAM flocculant named NP. Comparatively, another CPAM flocculant named SP with stable UV light intensity and single initiator was prepared. The chemical structure, morphology, and thermal stability were analyzed through instrumental analysis. Proton nuclear magnetic resonance indicated that NP was successfully prepared, and a small fraction of cationic homopolymer was mixed in the product. Polymerization conditions were optimized, and polymerization mechanism was determined by investigating the effects of various parameters on intrinsic viscosity, conversion, and dissolvability. Results showed that the best performance was obtained at indexes of 0.45 wt‰ redox initiator concentration, 0.2 wt‰ azo initiator concentration, 40.0 wt% of cationic monomer, first- and second-stage light intensities of 8.5 and 13 mW/cm2, respectively, and 3 wt% urea. Sludge conditioning performances of NP and SP were comparatively evaluated, and the mechanism was determined by investigating the sedimentation behavior and floc size distribution. High intrinsic viscosity, porous morphology structure, and the mixed cationic homopolymer of NP resulted in better sludge conditioning performance.

scholarly journals Preparation, Characterization, and Sludge Conditioning of Cationic Polyacrylamide Synthesized by a Novel UVA-Initiated System

Processes ◽  
2018 ◽  
Vol 6 (12) ◽  
pp. 233 ◽  
Author(s):  
Qingqing Guan ◽  
Guocheng Zhu ◽  
Yi Liao ◽  
Jin Xu ◽  
Xiaoxu Sun ◽  
...  
Keyword(s):  
Light Intensity ◽  
Intrinsic Viscosity ◽  
Initiator Concentration ◽  
Floc Size ◽  
Cationic Polyacrylamide ◽  
Sedimentation Behavior ◽  
Uva Light ◽  
Redox Initiator ◽  
Sludge Conditioning ◽  
Azo Initiator

Controlling the concentration of free radicals in polymerization systems is advantageous for preparing cationic polyacrylamide (CPAM) with a high molecular weight and acceptable dissolvability. In this study, a novel ultraviolet (UVA)-initiated system characterized by an adjustable light intensity and a redox-azo complex initiator was used to synthesize a CPAM flocculant named NP. Comparatively, another CPAM flocculant named SP with a stable UVA light intensity and a single initiator was prepared. Their chemical structure, morphology, and thermal stability were analyzed through instrumental analysis. 1H NMR indicated that NP was successfully prepared, and a small fraction of a cationic homopolymer was mixed in the product. Polymerization conditions of NP were optimized, and polymerization mechanism was determined by investigating the effects of various parameters on intrinsic viscosity, conversion, and dissolvability. Results showed that the best performance was obtained at indices of 0.45 wt‰ redox initiator concentration, 0.2 wt‰ azo initiator concentration, 40.0 wt% cationic monomer, 3 wt‰ urea, and first- and second-stage light intensities of 8.5 and 13 mW/cm2, respectively. The sludge conditioning performances of NP and SP were comparatively evaluated, and the mechanism was determined by examining sedimentation behavior and floc size distribution. High intrinsic viscosity, porous morphology structure, and mixed NP cationic homopolymer contributed to the improvement of sludge conditioning performance.

scholarly journals Dual-Wavelength (UV and Blue) Controlled Photopolymerization Confinement for 3D-Printing: Modeling and Analysis of Measurements

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1819 ◽  
Author(s):  
Jui-Teng Lin ◽  
Da-Chuan Cheng ◽  
Kuo-Ti Chen ◽  
Hsia-Wei Liu
Keyword(s):  
Light Intensity ◽  
Blue Light ◽  
Uv Light ◽  
Numerical Data ◽  
Coupling Factor ◽  
Dual Wavelength ◽  
Continuous Exposure ◽  
Initiator Concentration ◽  
Modeling And Analysis ◽  
Inhibition Effect

The kinetics and modeling of dual-wavelength (UV and blue) controlled photopolymerization confinement (PC) are presented and measured data are analyzed by analytic formulas and numerical data. The UV-light initiated inhibition effect is strongly monomer-dependent due to different C=C bond rate constants and conversion efficacies. Without the UV-light, for a given blue-light intensity, higher initiator concentration (C10) and rate constant (k’) lead to higher conversion, as also predicted by analytic formulas, in which the total conversion rate (RT) is an increasing function of C1 and k’R, which is proportional to k’[gB1C1]0.5. However, the coupling factor B1 plays a different role that higher B1 leads to higher conversion only in the transient regime; whereas higher B1 leads to lower steady-state conversion. For a fixed initiator concentration C10, higher inhibitor concentration (C20) leads to lower conversion due to a stronger inhibition effect. However, same conversion reduction was found for the same H-factor defined by H0 = [b1C10 − b2C20]. Conversion of blue-only are much higher than that of UV-only and UV-blue combined, in which high C20 results a strong reduction of blue-only-conversion, such that the UV-light serves as the turn-off (trigger) mechanism for the purpose of spatial confirmation within the overlap area of UV and blue light. For example, UV-light controlled methacrylate conversion of a glycidyl dimethacrylate resin is formulated with a tertiary amine co-initiator, and butyl nitrite. The system is subject to a continuous exposure of a blue light, but an on-off exposure of a UV-light. Finally, we developed a theoretical new finding for the criterion of a good material/candidate governed by a double ratio of light-intensity and concentration, [I20C20]/[I10C10].

scholarly journals Dual-Wavelength (UV and Blue) Controlled Photopolymerization Confinement for 3D-Printing: Modeling and Analysis of Measurements

2019 ◽  
Author(s):  
Jui-Teng Lin ◽  
Da-Chuan Cheng ◽  
Kuo-Ti Chen ◽  
Hsia-Wei Liu
Keyword(s):  
Light Intensity ◽  
Blue Light ◽  
Uv Light ◽  
Numerical Data ◽  
Coupling Factor ◽  
Dual Wavelength ◽  
Continuous Exposure ◽  
Initiator Concentration ◽  
Modeling And Analysis ◽  
Inhibition Effect

The kinetics and modeling of dual-wavelength controlled photopolymerization confinement (PC) are presented and measured data are analyzed by analytic formulas and numerical data. The UV-light initiated inhibition effect is strongly monomer-dependent and different monomers have different C=C bond rate constants and conversion efficacy. Without the UV-light, for a given blue-light intensity, higher initiator concentration (C10) and rate constant (k’) lead to higher conversion, as also predicted by analytic formulas, in which the total conversion rate (RT) is an increasing function of k’R, which is proportional to k[gB1C1]0.5. However, the coupling factor b1 plays a different role that higher b1 leads to higher conversion only in the transient regime; whereas higher b1 leads lower steady-state conversion. For a fixed initiator concentration C10, higher inhibitor concentration (C20) leads to lower conversion due to stronger inhibition effect. However, same conversion reduction was found for the same H-factor of H0 = [b1C10 - b2C20]. Conversion of blue-only are much higher than that of UV-only and UV-blue combined, in which high C20 results a strong reduction of blue-only-conversion, such that the UV-light serves as the turn-off (trigger) mechanism for the purpose of spatial confirmation within the overlap area of UV and blue light. For example, UV-light controlled methacrylate conversion of a glycidyl dimethacrylate resin formulated with a tertiary amine co-initiator, and butyl nitrite, subject to a continuous exposure of a blue light, but an on-off exposure of a UV-light. Finally, we developed a theoretical new finding for the criterion of a good material/candidate governed by a double ratio of light-intensity and concentration, [I20C20.]/[I10C10].

scholarly journals Photodegradation of Trace Trichloronitromethane in Water under UV Irradiation

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Lin Deng ◽  
Zhiren Wu ◽  
Caiqian Yang ◽  
Yung-Li Wang
Keyword(s):  
Humic Acid ◽  
Light Intensity ◽  
Uv Light ◽  
Control Strategies ◽  
Chloride Ions ◽  
Source Control ◽  
Photochemical Degradation ◽  
Nitrate Ions ◽  
Photodegradation Rate ◽  
Water And Wastewater

This study’s objective was to study the photodegradation of TCNM (trichloronitromethane) in water under UV light. The effects of light intensity, nitrate ions, chloride ions, humic acid, and pH on the photochemical degradation of TCNM were investigated under the irradiation of low pressure mercury lamp (λ= 254 nm, 12 W). The photodegradation rate of TCNM was found to increase with increasing the concentration of nitrate ions, chloride ions, humic acid, pH, and light intensity. The photodegradation of TCNM was examined at pH 6.0 with initial concentrations (C0) of TCNM at 10.0–200.0 µg/L. The overall rate of degradation of TCNM was modeled using a pseudofirst-order rate law. Finally, the proposed mechanism involved in the photodegradation of TCNM was also discussed by analysis. Results of this study can contribute to the development of new source control strategies for minimization of TCNM risk at drinking water and wastewater utilities.

scholarly journals Treatment of High-Strength Animal Industrial Wastewater Using Photo-Assisted Fenton Oxidation Coupled to Photocatalytic Technology

Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1553 ◽  
Author(s):  
Jae Hong Park ◽  
Dong Seok Shin ◽  
Jae Kwan Lee
Keyword(s):  
Light Intensity ◽  
Removal Efficiency ◽  
Industrial Wastewater ◽  
Uv Light ◽  
High Strength ◽  
Cod Removal ◽  
Fenton Oxidation ◽  
Optimal Conditions ◽  
Experimental Conditions ◽  
Animal Wastewater

Animal wastewater is one of the wastewaters that has a color and is difficult to treat because it contains a large amount of non-degradable organic materials. The photo-assisted Fenton oxidation technique was applied to treat animal wastewater, and the optimal conditions of chemical oxygen demands (COD) removal were analyzed according to changes in pH, ferrous ion, H2O2, and ultraviolet (UV) light intensity as a single experimental condition. Experimental results showed that, under the single-factor experimental conditions, the optimal conditions for degradation of animal wastewater were pH 3.5, Fe(II) 0.01 M, H2O2 0.1 M, light intensity 3.524 mW/m2. Under the optimal conditions, COD removal efficiency was 91%, sludge production was 2.5 mL from 100 mL of solution, color removal efficiency was 80%, and coliform removal efficiency was 99.5%.

Kinetic Study of Photoinitiated Frontal Polymerization. Influence of UV Light Intensity Variations on the Conversion Profiles

2010 ◽  
Vol 43 (1) ◽  
pp. 177-184 ◽  
Author(s):  
N. Hayki ◽  
L. Lecamp ◽  
N. Désilles ◽  
P. Lebaudy
Keyword(s):  
Light Intensity ◽  
Kinetic Study ◽  
Uv Light ◽  
Frontal Polymerization

scholarly journals Synthesis of a Cationic Polyacrylamide under UV Initiation and Its Flocculation in Estrone Removal

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Jiaoxia Sun ◽  
Xiqin Ma ◽  
Xiang Li ◽  
Jianxin Fan ◽  
Qingkong Chen ◽  
...  
Keyword(s):  
Ammonium Chloride ◽  
Removal Rate ◽  
Phenyl Group ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry ◽  
Floc Size ◽  
Cationic Polyacrylamide ◽  
H Nmr ◽  
Ft Ir ◽  
Dsc Analyses

A ternary cationic polyacrylamide (CPAM) with the hydrophobic characteristic was prepared through ultraviolet- (UV-) initiated polymerization technique for the estrone (E1) environmental estrogen separation and removal. The monomers of acrylamide (AM), acryloyloxyethyl-trimethyl ammonium chloride (DAC), and acryloyloxyethyl dimethylbenzyl ammonium chloride (AODBAC) were used to synthesize the ternary copolymer (PADA). Fourier transform infrared spectroscopy (FT-IR), 1H nuclear magnetic resonance spectroscopy (1H NMR), thermogravimetry/differential scanning calorimetry (TG/DSC), and scanning electron microscopy (SEM) were employed to characterize the structure, thermal decomposition property, and morphology of the polymers, respectively. FT-IR and 1H NMR results indicated the successful formation of the polymers. Besides, with the introduction of hydrophobic groups (phenyl group), an irregular and porous surface morphology and a favorable thermal stability of the PADA were observed by SEM and TG/DSC analyses, respectively. At the optimal condition (pH = 7, flocculant dosage = 4.0 mg/L and E1 concentration = 0.75 mg/L), an excellent E1 flocculation performance (E1 removal rate: 90.1%, floc size: 18.3 μm, and flocculation kinetics: 22.69×10-4 s−1) was acquired by using the efficient flocculant PADA-3 (cationic degree = 40%, and intrinsic viscosity = 6.30 dL·g−1). The zeta potential and floc size analyses were used to analyze the possible flocculation mechanism for the E1 removal. Results indicated that the charge neutralization, adsorption, and birding effects were dominant in the E1 removal progress.

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.

Preparation and Photocatalytic Activity of Silver Doped TiO2 Nanotubes

2014 ◽  
Vol 618 ◽  
pp. 14-18
Author(s):  
Ying Cao Xu ◽  
Hong You
Keyword(s):  
Acetic Acid ◽  
Photocatalytic Activity ◽  
Light Intensity ◽  
Anodic Oxidation ◽  
Ag Nanoparticles ◽  
Uv Light ◽  
Effect Factors ◽  
Glycerol Water ◽  
Surface Modified

In this paper, highly ordered TiO2 nanotubes were performed by the method of anodic oxidation, using glycerol / water, NH4F as the electrolyte, and Oxidation voltage to 25v for 1h. TiO2 nanotube surface modified by Ag nanoparticles, by using UV light to restore Ag+ to Ag, the Ag+ from AgNO3 solution sputted out by ultrasonic. Ag-doped TiO2 was used to degrade acetic acid concentrations under UV light. Different Ag/TiO2, HAc concentration, and light intensity were selected as effect factors, TiO2 as contrast test.

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