scholarly journals Photooxidation Contribution Study on the Decomposition of Azo Dyes in Aqueous Solutions by VUV-Based AOPs

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Chih-Ming Ma ◽  
Gui-Bing Hong ◽  
Hua-Wei Chen ◽  
Nguyen-Thi Hang ◽  
Yung-Shuen Shen
Keyword(s):  
Azo Dyes ◽  
Ph Value ◽  
Reaction Rates ◽  
Degradation Of Dyes ◽  
Degradation Rates ◽  
Effects Of Ph ◽  
Alkaline Conditions ◽  
Acidic Conditions ◽  
High Concentrations ◽  
Acid Blue

The effects of pH value, VUV intensity, initial dye concentration, initial H2O2concentration, and TiO2loading dose on the degradation of three azo dyes: acid Orange 8, acid Blue 29, and acid Blue 113 were studied to explore and compare the treatment efficiencies among the adopted AOPs. It was found that pH played an important role in the degradation of dyes using VUV irradiation. For VUV/H2O2, VUV/TiO2, and VUV/TiO2/H2O2processes, the decoloration rates of the three azo dyes were more efficient under acidic conditions relative to alkaline conditions. The degradation rates of dyes increased with increasing concentrations of H2O2, but reaction rates were retarded at high concentrations of H2O2because the H2O2compound acted as a scavenger of the hydroxyl radical. In this paper, three azo dyes were decomposed efficiently by VUV irradiation only demonstrating the effectiveness of VUV direct photolysis.

Effects of pH on photocatalysis of 2,4,6-trichlorophenol in aqueous TiO2 suspensions

1994 ◽  
Vol 30 (9) ◽  
pp. 47-57 ◽  
Author(s):  
Shuzo Tanaka ◽  
Uttam Kumar Saha
Keyword(s):  
Sodium Chloride ◽  
Degradation Rate ◽  
Parent Compound ◽  
Photocatalytic Decomposition ◽  
Illumination Time ◽  
Effects Of Ph ◽  
Alkaline Conditions ◽  
Na Ions ◽  
Acidic Conditions

The effects of pH on the photocatalytic decomposition of 2,4,6-trichlorophenol (TCP) were investigated in the presence of titanium dioxide suspensions illuminated by a high pressure mercury lamp over the wavelength range of 302-405 nm. Higher degradation rate was observed under alkaline conditions than acidic conditions. Although a rapid adsorption of TCP onto the TiO2 surface was observed at low pH and no adsorption at high pH, the role of adsorption of TCP was found insignificant in photocatalysis. With sodium chloride addition, a decrease in reaction rate was observed at pH 5 due to Cl− ions inhibition, but at pH 10 the same anions had no adverse effect on the measured photocatalytic efficiency and Na+ ions enhanced the degradation rate of TCP. With no oxygen, however, the photocatalytic decomposition of TCP in sodium chloride solution gives lower degradation rate than with dissolved oxygen and no sodium chloride at various pH. Complete mineralization requires a longer illumination time than the decomposition of the parent compound. A mechanism for the reaction based on photogeneration of hydroxyl radicals was proposed.

High Performance Liquid Chromatographic Analysis of Degradation Products of Tinidazole Pills

2013 ◽  
Vol 377 ◽  
pp. 261-264 ◽  
Author(s):  
Ting Xia ◽  
Jian Kang Wang ◽  
Tao Jiang ◽  
Jing Li
Keyword(s):  
High Performance ◽  
Ph Value ◽  
Degradation Products ◽  
High Performance Liquid Chromatographic ◽  
Melting Time ◽  
Alkaline Conditions ◽  
Direct Preparation ◽  
Liquid Chromatographic Analysis ◽  
Acidic Conditions ◽  
Liquid Chromatographic

To study the effect of different pH on degradation products of tinidazole pills and direct preparation of tinidazole pills, Tinidazole pills were prepared and the solution of different pH was compounded. The tinidazole content of pills and degradation products were determined by being heated at 80°C via high performance liqud chromatographic (HPLC). The number and concentration of tinidazole pills were increased with the increase of temperature and pH. Tinidazole pills in acidic conditions with the pH value within 4~5 were more stable than in neutral and alkaline conditions. It was shown that shortening the melting time and keeping pH value within 4~5 were in favor of preparation and assurance of pills quality.

The Study on the Electrocatalytic Treatment of Dye Wastewater by ACF Cathode

2011 ◽  
Vol 356-360 ◽  
pp. 1386-1390
Author(s):  
Jun Sheng Hu ◽  
Yue Li ◽  
Hui Wang
Keyword(s):  
Current Density ◽  
Electrolyte Concentration ◽  
Ph Value ◽  
Strong Adsorption ◽  
Stainless Steel Cathode ◽  
Initial Ph ◽  
Operating Current ◽  
Alkaline Conditions ◽  
Acidic Conditions ◽  
Better Than

By using ACF as the cathode, acid scarlet 3R as simulated wastewater, the experiment researches into the effect of current density, aeration, electrolyte concentration and the initial pH value on the color removal of wastewater. The results showed that: ACF cathode has a strong adsorption capacity. Oxygen is reduced to H2O2 and other oxidizing substances H2O2 on the cathode surface .Therefore, it has a strong degradation capacity to dye, which is far better than that of the stainless steel cathode; Lower operating current density helps reduce processing costs; Higher electrolyte concentration and aeration is not necessarily better, which follows certain rules; The treatment is effected greatly by the initial pH, and the effect of decolonization in the acidic conditions is better than that in alkaline conditions. When the current density is 6Am/cm², electrolyte concentration is 0.04mol•L-1, aeration capacity is 0.2m3/h, initial pH is 3.5 and the time of treatment is 70min, the decolonization rate of wastewater is 95.30 %.

Study of the phenolic compounds formed during pretreatment of sugarcane bagasse by wet oxidation and steam explosion

Holzforschung ◽  
2007 ◽  
Vol 61 (5) ◽  
pp. 483-487 ◽  
Author(s):  
Carlos Martín ◽  
Helene B. Klinke ◽  
Marcelo Marcet ◽  
Luis García ◽  
Ena Hernández ◽  
...  
Keyword(s):  
Phenolic Compounds ◽  
Sugarcane Bagasse ◽  
Steam Explosion ◽  
Total Content ◽  
Wet Oxidation ◽  
Aldehydes And Ketones ◽  
Alkaline Conditions ◽  
Acidic Conditions ◽  
High Concentrations ◽  
Ferulic Acids

Abstract The formation of phenolic compounds during pretreatment of sugarcane bagasse was investigated. Bagasse was pretreated by wet oxidation (WO) at 195°C during 15 min under either alkaline or acidic conditions and by steam explosion (STEX) at 205°C during 10 min. The total content of phenolic compounds in the prehydrolysates was determined spectrophotometrically. Under acidic and alkaline WO conditions, 3.8% (w/w) and 3% phenols were found, respectively. STEX gave rise to 1.9% phenols. Individual phenols were identified by GC-MS. Phenylpropanoid derivatives, such as p-coumaric and ferulic acids, accounted for more than 50% of the phenols identified in STEX prehydrolysates. In WO prehydrolysates, on the other hand, phenols lacking the propanoid side chain were predominant. Of the latter, p-hydroxybenzaldehyde was the most abundant phenol, with concentrations of 0.27% (acidic conditions) and 0.15% (alkaline conditions). As expected, high concentrations of oxidised compounds were generally observed in WO prehydrolysates, such as carboxylic acids, aldehydes and ketones. This is a true reflection of the oxidative conditions during WO pretreatment.

scholarly journals Effects of KBr and KI on Photocatalytic Degradation of Dye W-7G with Nano-TiO2 as Catalyst

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Chao Zou ◽  
Qi-Jin Geng ◽  
Jing-Tuo Zhu ◽  
Chen Jing ◽  
Wen Zhong ◽  
...  
Keyword(s):  
Photocatalytic Degradation ◽  
Inorganic Salt ◽  
Ph Value ◽  
Nano Tio2 ◽  
Photocatalytic Reactor ◽  
Theoretical Support ◽  
Maximum Value ◽  
Degradation Of Dyes ◽  
Bubbling Fluidized Bed ◽  
Alkaline Conditions

To investigate the influence of inorganic salt on the photocatalytic degradation, the effects of KBr and KI at various concentrations and pH values on the photocatalytic degradation of dye W-7G using nanoscaled titanium dioxide as photocatalyst in a bubbling fluidized bed photocatalytic reactor (BFBPR) were studied. The results indicated that the degradation apparent rate constant ( K app ) of the system with KI was clearly higher than that with KBr under acidic or alkaline conditions. And the maximum value of K app (0.01127) appeared at the KI concentration of 0.075 g L-1 with a pH value of 9.37, meaning the highest degradation efficiency. Furthermore, the possible mechanism of photocatalytic degradation of W-7G in the presence of KBr and KI was proposed, which could provide a theoretical support for the further study of inorganic salt effects on the photocatalytic degradation of dyes.

scholarly journals Sulfate radicals-based degradation of antraquinone textile dye in a plug flow photoreactor

2019 ◽  
Vol 84 (9) ◽  
pp. 1041-1054 ◽  
Author(s):  
Jelena Mitrovic ◽  
Radovic Vucic ◽  
Milos Kostic ◽  
Nena Velinov ◽  
Slobodan Najdanovic ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Textile Industry ◽  
Ph Value ◽  
Plug Flow ◽  
Textile Dye ◽  
Sulfate Radicals ◽  
Degradation Rates ◽  
Initial Ph ◽  
Acidic Conditions ◽  
Uv C

The study evaluated the degradation of the antraquinone textile dye reactive blue 19, a frequently used dye in the textile industry, by means of sulfate radicals. Sulfate radicals were generated by activation of peroxydisulfate with UV-C (254 nm) irradiation. UV irradiation alone did not affect the removal efficiency, while with the addition of an oxidant, the removal efficiency was significantly improved. The degradation rates of the textile dye increased at higher initial dosages of oxidant, while the opposite trend was observed in the case of increasing initial dye concentration. Acidic conditions were more convenient for degradation of the dye then neutral or basic. Degradation of the textile dye was not affected by the presence of bicarbonate and chloride anions within the concentrations range from 1 to 200 mmol?L-1. The presence of carbonate showed a suppressing effect on the removal efficiency, especially at carbonate levels below 20 mmol?L-1. However, at carbonate levels greater than 20 mmol?L-1, the dye removal efficiency increased. The use of methanol and tert-butanol as scavengers revealed that both radicals, HO?and SO4?-, would be generated depending on initial pH value of the dye solution.

scholarly journals Single and combined removal of Cr(VI) and Cd(II) by nanoscale zero-valent iron in the absence and presence of EDDS

2017 ◽  
Vol 76 (5) ◽  
pp. 1261-1271 ◽  
Author(s):  
Haoran Dong ◽  
Yalan Zeng ◽  
Yankai Xie ◽  
Qi He ◽  
Feng Zhao ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Zero Valent Iron ◽  
Inhibition Effect ◽  
Insignificant Effect ◽  
Removal Process ◽  
Nanoscale Zero Valent Iron ◽  
Effects Of Ph ◽  
Alkaline Conditions ◽  
Acidic Conditions ◽  
Ph Dependent

This study examined the feasibility of nanoscale zero-valent iron (nZVI) for the single and combined removal of Cr(VI) and Cd(II) with or without ethylene diamine disuccinic acid (EDDS). The effects of pH and dissolved oxygen (DO) on the removal process were investigated. Results show that the single removal of either Cr(VI) or Cd(II) by nZVI was pH dependent, where the higher Cr(VI) removal was achieved under acidic conditions, whereas the higher Cd(II) removal was achieved under alkaline conditions. The presence of DO enhanced Cd(II) removal but inhibited Cr(VI) removal under alkaline conditions. In the co-existence of Cr(VI) and Cd(II), it was found that Cd(II) exerted insignificant effect on Cr(VI) removal, while the presence of Cr(VI) remarkably enhanced the Cd(II) removal. The addition of EDDS exhibited different influences on Cr(VI) and Cd(II) removal, which were associated with pH and DO. The EDDS enhanced Cr(VI) removal at pH 5.6–9.0 in the absence of DO, but decreased Cr(VI) removal at pH 9.0 in the presence of DO. For the removal of Cd(II) at pH 5.6–7.0, either facilitation or inhibition effect of EDDS was observed, depending on EDDS concentration and the co-existence of Cr(VI). However, Cd(II) removal was always significantly inhibited by EDDS at pH 9.0.

scholarly journals The Comparison of Photocatalytic Degradation and Decolorization Processes of Dyeing Effluents

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Ewa Adamek ◽  
Wojciech Baran ◽  
Justyna Ziemiańska ◽  
Andrzej Sobczak
Keyword(s):  
Photocatalytic Degradation ◽  
Azo Dyes ◽  
Cationic Dyes ◽  
Photocatalytic Process ◽  
Anionic Dyes ◽  
Degradation Of Dyes ◽  
Textile Dyeing ◽  
High Concentrations ◽  
Very High ◽  
Photocatalytic Processes

Treatment of dye effluents resulting from the industrial scale dyeing of cotton, polyacrylic fibres, leather, and flax fabrics by photocatalytic methods was investigated. Photocatalytic processes were initiated by UV-a light (λmax366 nm) and were conducted in the presence of TiO2, TiO2/FeCl3, or FeCl3as photocatalysts. It was found that the photocatalytic process carried out with TiO2and TiO2/FeCl3was the most effective method for decolorization of textile dyeing effluents and degradation of dyes, except for effluents containing very high concentrations of stable azo dyes. During the photocatalytic degradation of anionic dyes, a mixture of TiO2/FeCl3was more effective, while in the case of cationic dyes, more suitable seems to be TiO2alone.

DIP quality influenced by process water quality

TAPPI Journal ◽  
2014 ◽  
Vol 13 (9) ◽  
pp. 51-60
Author(s):  
DENNIS VOSS ◽  
HANS-JOACHIM PUTZ ◽  
SAMUEL SCHABEL
Keyword(s):  
Water Quality ◽  
Surface Tension ◽  
Ph Value ◽  
Water Hardness ◽  
Process Water ◽  
Test Results ◽  
Negative Effects ◽  
Water Parameters ◽  
Effects Of Ph ◽  
Contamination Levels

The need for deinking mills to reduce their fresh water consumption has resulted in higher loads of various contaminants in the process water. Lower recovered paper quality also leads to higher contamination levels in the mills. This higher load has an influence on achievable target brightness. The objective of the work was to determine and explain the main reasons for relatively poor deinked pulp quality or poor deinking potential based on the influence of recovered paper composition and process water quality. The process water parameters significantly affect the deinking potential of recovered paper. The test results showed the negative effects of increased water hardness. For standard recovered paper mixtures, flotation selectivity is higher with increasing flotation pH-value. Good results were realized for standard recovered paper with low hardness, low surface tension, and high pH-value. The results for recovered paper containing flexo newsprint could be slightly improved with low hardness, low surface tension, and low pH-value. The results of the test program using design of experiments showed interacting effects of pH-value and surface tension on luminosity and flotation selectivity.

Efficient Preconcentration of Cu2+, Zn2+ and Fe3+ with an Agarose-Schiff Base Sorbent

2007 ◽  
Vol 72 (7) ◽  
pp. 908-916 ◽  
Author(s):  
Payman Hashemi ◽  
Hatam Hassanvand ◽  
Hossain Naeimi
Keyword(s):  
Schiff Base ◽  
Metal Ions ◽  
Metal Ion ◽  
Good Accuracy ◽  
Kinetic Studies ◽  
Sample Volume ◽  
Effects Of Ph ◽  
Glass Column ◽  
High Concentrations ◽  
Ph Range

Sorption and preconcentration of Cu2+, Zn2+ and Fe3+ on a salen-type Schiff base, 2,2'- [ethane-1,2-diylbis(nitrilomethylidyne)]bis(2-methylphenol), chemically immobilized on a highly crosslinked agarose support, were studied. Kinetic studies showed higher sorption rates of Cu2+ and Fe3+ in comparison with Zn2+. Half-times (t1/2) of 31, 106 and 58 s were obtained for sorption of Cu2+, Zn2+ and Fe3+ by the sorbent, respectively. Effects of pH, eluent concentration and volume, ionic strength, buffer concentration, sample volume and interferences on the recovery of the metal ions were investigated. A 5-ml portion of 0.4 M HCl solution was sufficient for quantitative elution of the metal ions from 0.5 ml of the sorbent packed in a 6.5 mm i.d. glass column. Quantitative recoveries were obtained in a pH range 5.5-6.5 for all the analytes. The volumes to be concentrated exceeding 500 ml, ionic strengths as high as 0.5 mol l-1, and acetate buffer concentrations up to 0.3 mol l-1 for Zn2+ and 0.4 mol l-1 for Cu2+ and Fe3+ did not have any significant effect on the recoveries. The system tolerated relatively high concentrations of diverse ions. Preconcentration factors up to 100 and detection limits of 0.31, 0.16 and 1.73 μg l-1 were obtained for Cu2+, Zn2+ and Fe3+, respectively, for their determination by a flame AAS instrument. The method was successfully applied to the metal ion determinations in several river water samples with good accuracy.

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