Electrochemical oxidation of polyvinyl alcohol using a RuO2/Ti anode (original) (raw)
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DSA electrochemical treatment of olive mill wastewater on Ti/RuO 2 anode
Journal of Applied Electrochemistry, 2010
The electrochemical oxidation of olive mill wastewater (OMW) over a Ti/RuO 2 anode was studied by means of cyclic voltammetry and bulk electrolysis and compared with previous results over a Ti/IrO 2 anode. Experiments were conducted at 300-1,220 mg L -1 initial chemical oxygen demand (COD) concentrations, 0.05-1.35 V versus SHE and 1.39-1.48 V versus SHE potential windows, 15-50 mA cm -2 current densities, 0-20 mM NaCl, Na 2 SO 4 , or FeCl 3 concentrations, 80°C temperature, and acidic conditions. Partial and total oxidation reactions occur with the overall rate being near first-order kinetics with respect to COD. Oxidation at 28 Ah L -1 and 50 mA cm -2 leads to quite high color and phenols removal (86 and 84%, respectively), elimination of ecotoxicity, and a satisfactory COD and total organic carbon reduction (52 and 38%, respectively). Similar performance can be achieved at the same charge (28 Ah L -1 ) using lower current densities (15 mA cm -2 ) but in the presence of various salts. For example, COD removal is less than 7% at 28 Ah L -1 in a salt-free sample, while addition of 20 mM NaCl results in 54% COD reduction. Decolorization of OMW using Ti/RuO 2 anode seems to be independent of the presence of salts in contrast with Ti/IrO 2 where addition of NaCl has a beneficial effect on decolorization.
DSA electrochemical treatment of olive mill wastewater on Ti/RuO2 and Ti/IrO2 anodes
2009
The electrochemical oxidation of olive mill wastewater (OMW) over a Ti/RuO 2 anode was studied by means of cyclic voltammetry and bulk electrolysis and compared with previous results over a Ti/IrO 2 anode. Experiments were conducted at 300-1,220 mg L-1 initial chemical oxygen demand (COD) concentrations, 0.05-1.35 V versus SHE and 1.39-1.48 V versus SHE potential windows, 15-50 mA cm-2 current densities, 0-20 mM NaCl, Na 2 SO 4 , or FeCl 3 concentrations, 80°C temperature, and acidic conditions. Partial and total oxidation reactions occur with the overall rate being near first-order kinetics with respect to COD. Oxidation at 28 Ah L-1 and 50 mA cm-2 leads to quite high color and phenols removal (86 and 84%, respectively), elimination of ecotoxicity, and a satisfactory COD and total organic carbon reduction (52 and 38%, respectively). Similar performance can be achieved at the same charge (28 Ah L-1) using lower current densities (15 mA cm-2) but in the presence of various salts. For example, COD removal is less than 7% at 28 Ah L-1 in a salt-free sample, while addition of 20 mM NaCl results in 54% COD reduction. Decolorization of OMW using Ti/RuO 2 anode seems to be independent of the presence of salts in contrast with Ti/IrO 2 where addition of NaCl has a beneficial effect on decolorization.
Electrochemical oxidation of textile wastewater and its reuse
Journal of Hazardous Materials, 2007
It is attempted in the present investigation to treat organic pollutant present in the textile effluent using an electrochemical treatment technique. Experiments are carried out in a batch electrochemical cell covering wide range in operating conditions. Due to the strong oxidizing potential of the chemicals produced, the effluent COD is reduced substantially in this treatment technique. The influence of effluent initial concentration, pH, supporting electrolyte concentration and the anode material on pollutant degradation has been critically examined.
Journal of Hazardous Materials, 2009
The electrochemical oxidation of olive mill wastewater (OMW) and model compounds over a Ti/IrO2 anode was studied by means of cyclic voltammetry and bulk electrolysis. Experiments were conducted at 1300 mg/L initial COD, 0–1.23 V vs SHE and 1.4–1.54 V vs SHE potential windows, 50 mA/cm2 current density, 0–25 mM NaCl, 60–80 °C temperature and acidic conditions. The reactivity of model compounds decreases in the order phenol ≈ p-coumaric acid > cinnamic acid > caffeic acid. Partial and total oxidation reactions occur with the overall rate following zero-order kinetics with respect to COD and increasing with temperature. Oxidation of OMW at 43 Ah/L, 80 °C and in the presence of 5 mM NaCl leads to complete color and phenols removal, elimination of ecotoxicity but moderate (30%) COD reduction. Similar performance can be achieved at 6 Ah/L in the presence of 15 mM NaCl. In the absence of salt, the respective color and phenols removal (at 6 Ah/L) is less than 10%. Excessive salinity (25 mM), although does not change color, phenols and COD removal, has an adverse effect on ecotoxicity.
Electrochemical treatment of pharmaceutical wastewater by combining anodic oxidation with ozonation
Journal of Environmental Science and Health Part A-toxic/hazardous Substances & Environmental Engineering, 2008
The electrochemical behavior of pharmaceutical azo dye amaranth has been investigated in distilled water and Britton-Robinson buffer. One well-defined irreversible cathodic peak is observed. This may be attributed to the reduction of the -N=N-group. Calculation of the number of electrons transferred in the reduction process has been performed and a reduction mechanism proposed. Results indicate that the electrode process is diffusion controlled. The cathodic peak in the case of controlled potential electrolysis is found to reduce substantially with a decrease in color and absorbance. The reaction has first order kinetics with k value 5.75 9 10 -2 abs min -1 . The efficiency of different electrode materials (platinum and steel) for decolorisation is compared. Chemical oxygen demand (COD) decreases substantially from 2,680 to 96 ppm at platinum and to 142 ppm at steel. This translates to 97% COD removal at platinum and 95% at steel.
2015
The electrochemical oxidation of paper industry wastewater was studied using two types of dimensionally stable anodes: Ti/RuO2 and Ti/RuIrCo(40%:40%:20%)Ox. The electrodes were characterized using SEM micrography and EDS spectroscopy. The local mapping analysis was performed on Ti/RuIrCo(40%:40%:20%)Ox. The presence of Ir and Co significantly modified the surface morphology of Ti/RuO2. The oxidation process was analyzed as a function of the electrolysis time at a constant cell potential in the absence or presence of an electrolyte (NaCl) and at an initial pH of 6.2. The effectiveness with which the two anodes electrochemically oxidized the wastewater was evaluated by measuring the removal of the chemical oxygen demand (COD), color, and total polyphenols, and using UV-Vis spectroscopy. The results revealed that both anodes reduced the COD, color, and polyphenols; however, the ability to remove organic matter depended on the nature of the electrode material, the presence or absence of...
Performance of Electrochemical Oxidation in Treating Textile Dye Wastewater by Stainless Steel Anode
Electrochemical oxidation for a textile dye wastewater collected from a textile processing industry was investigated in this study using Stainless Steel an anode. Number of batch experiments was run in a laboratory-scale. The results are reported in terms of percentage removal of Chemical Oxygen Demand (COD), Color and variations in BOD/COD ratio for different current densities of 12, 24 and 48 A/m 2 . For current densities 12, 24 and 48 A/m 2 , COD was reduced by 52%, 63% and 71% respectively; Color was reduced by 41%, 55%, 77% respectively. The biodegradability was improved because of the increase BOD/COD ratio from 0.1 to 0.58. It was observed that increasing the electrolysis time and increased current density bring down the concentration of pollutants. COD removal and energy consumption rates are discussed. Kinetics for COD removal is also discussed. It can be concluded from the results that SS as an anode found to be effective in treating this electrolyte and could be effectively used for pretreatment of textile dye wastewater.
Treatment of Textile Wastewater by Electrochemical Method
In this study, the textile dying effluent treatment by electrochemical oxidation technique is optimized experimentally. It was identified that copper and stainless steel were the best anode and cathode materials respectively. The operational parameters such as supporting electrolyte (sodium chloride) concentration, initial pH and electrolysis time on pH changes and percentage of color, Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), Total Organic Carbon (TOC) were determined. The optimum range for each of these operating variables was experimentally investigated. The results show that the percentage of color, COD, BOD, TOC are removed effectively in the aqueous solution. The optimum conditions identified for electrochemical oxidation technique are 0.1M Nacl concentration, 7.67 pH and 105 minutes electrolysis time. Under these conditions the percentage of color and COD removal efficiencies were reached 96.2, while for BOD and TOC removals the percentage is slightly lower.
Treatment of Desizing Wastewater Containing Poly(vinyl alcohol) by Wet Air Oxidation
Industrial & Engineering Chemistry Research, 2000
The effectiveness of wet air oxidation (WAO) is studied in a 2-L autoclave for the treatment of desizing wastewater from man-made fiber textile plants. At an oxygen pressure of less than 2 MPa, over 30-min, chemical oxygen demand (COD) removal was found to increase from 15 to 65% when the temperature was raised from 150 to 250°C. The biodegradability of the wastewater was also simultaneously increased. Up to 90% of the COD could be removed within 120 min. A simplified reaction mechanism is proposed which involves a direct mineralization step in parallel with a step in which an intermediate is formed prior to mineralization. A kinetic model for COD removal was developed based on this reaction mechanism. The model was tested with experimental COD results over the temperature range of the experiments. The dependence of the specific reaction rate constants was found to follow the Arrhenius type of equation. The direct oxidation of poly(vinyl alcohol) (PVA) to carbon dioxide and water is the dominant reaction step. The intermediates formed are not likely to be the acetic acid but may be short segments of PVA that are easily oxidized.
Journal of Environmental Health Science and Engineering
Background: Annually, large quantities of dyes are produced and consumed in different industries. The discharge of highly colored textile effluents to the aquatic environments causes serious health problems in living organisms. This paper investigates the performance of each of the electro-oxidation and electro-reduction pathways in the removal of reactive red 120 (RR120) from synthetic textile effluents using a novel electrochemical reactor. Methods: In the current study, a two-compartment reactor divided by cellulosic separator was applied in batch mode using graphite anodes and stainless steel cathodes. Central Composite Design was used to design the experiments and find the optimal conditions. The operational parameters were initial dye concentration (100-500 mg L −1), sodium chloride concentration (2500-12,500 mg L −1), electrolysis time (7.5-37.5 min), and current intensity (0.06-0.3 A). Results: The results showed that electro-oxidation was much more efficient than electro-reduction in the removal of RR120. According to the developed models, current intensity was the most effective factor on the electro-oxidation of RR120 as well as in power consumption (Coefficients of 12.06 and 0.73, respectively). With regard to the dye removal through electro-reduction, electrolysis time (coefficient of 8.05) was the most influential factor. Under optimal conditions (RR120 = 200 mg.L −1 , NaCl = 7914.29 mg.L −1 , current intensity = 0.12 A, and reaction time = 30 min), the dye was removed as 99.44 and 32.38% via electro-oxidation and electro-reduction mechanisms, respectively, with consuming only 1.21 kwhm −3 of electrical energy. Conclusions: According to the results, electro-oxidation using graphite anodes in a cell divided by cellulosic separator is very efficient, compared to electro-reduction, in the removal of RR120 from aqueous solutions.