Modeling approach to phenol oxidation by a sand-based packed-bed electrode system (SPBEs)

2012 ◽  
Vol 66 (2) ◽  
pp. 422-428 ◽  
Author(s):  
Lizhang Wang ◽  
Peng Li ◽  
Qian Yan
Keyword(s):  
Mass Transport ◽  
Current Density ◽  
Oxygen Demand ◽  
Cell Voltage ◽  
Packed Bed ◽  
Theoretical Description ◽  
Electrode System ◽  
Phenol Oxidation ◽  
Packed Bed Electrode ◽  
Initial Ph

A comparative study of phenol oxidation using pure electrolysis (PEs) and sand-based packed-bed electrode systems (SPBEs) was performed under conditions of phenol concentration 800 mg L−1, initial pH 6.5, current density 100 A m−2 and sodium sulfate (Na2SO4) 3.0% (w/w) on IrO2–Ta2O5/Ti anode. The results show quartz sand, a non-conducting material is incapable of expanding the electrode area and the phenol oxidation in SPBEs commences only at the electrode surface. From the theoretical description of the mass transport coefficient and chemical oxygen demand (COD), we confirm that the enhancement of the COD removal efficiency, current and space–time yields in SPBEs is due to the improvement of mass transport properties. The proposed SPBEs shows superiority to the PEs on saving energy at the same applied voltage, however, when operated under the same applied current density the energy consumption of the former would be much higher than that of the latter because of the rise of the applied cell voltage.

A new strategy for determination of current efficiency during electro-oxidation of aromatic compounds in a packed-bed system

2011 ◽  
Vol 63 (11) ◽  
pp. 2685-2691 ◽  
Author(s):  
Lizhang Wang ◽  
Yuemin Zhao ◽  
Qingyu Gao ◽  
Cheng Qian ◽  
Yunlong Hu
Keyword(s):  
Current Efficiency ◽  
Aromatic Compounds ◽  
Oxygen Demand ◽  
Packed Bed ◽  
Electrode System ◽  
Electrode Distance ◽  
Faradaic Current ◽  
Packed Bed Electrode ◽  
New Strategy ◽  
Electro Oxidation

The electro-oxidation of aromatic compounds in 4,4′-diaminostilbene-2,2′-disulfonic (DSD) acid wastewater on IrO2–Ta2O5/Ti anodes was studied. The current efficiency was evaluated in terms of chemical oxygen demand (COD) by introducing a new factor, the fraction of the Faradaic current to the total cell current (β) through the network analysis of packed bed electrode system (PBEs). Experimental results using an up-flow PBEs at current intensities ranging from 5 to 16 A m−2, flow rates ranging from 20 to 80 L h−1 and inter-electrode distance of 5 to 50 cm are in good agreement with the proposed equation. In addition, lower current density, increasing flow rate and larger inter-electrode distance are beneficial to enhance the current efficiency.

Electrochemical Treatment of Simulated Dye Wastewater

2012 ◽  
Vol 441 ◽  
pp. 555-558
Author(s):  
Feng Tao Chen ◽  
San Chuan Yu ◽  
Xing Qiong Mu ◽  
Shi Shen Zhang
Keyword(s):  
Current Density ◽  
Oxygen Demand ◽  
Electrochemical Treatment ◽  
Dye Wastewater ◽  
Electrolysis Time ◽  
Electrochemical Degradation ◽  
Mild Conditions ◽  
Thermal Decomposition Method ◽  
Initial Ph ◽  
Effects Of Ph

The Ti/SnO2-Sb2O3/PbO2 electrodes were prepared by thermal decomposition method and its application in the electrochemical degradation of a heteropolyaromatic dye, Methylene blue (MB), contained in simulated dye wastewater were investigated under mild conditions. The effects of pH, current density and electrolysis time on de-colorization efficiency were also studied. Chemical oxygen demand (COD) was selected as another parameter to evaluate the efficiency of this degradation method on treatment of MB wastewater. The results revealed that when initial pH was 6.0, current density was 50 mA·cm2, electrolysis time was 60 min, Na2SO4 as electrolyte and its concentration was 3.0 g·dm3, the de-colorization and COD removal efficiency can reach 89.9% and 71.7%, respectively.

Combined technology for clomazone herbicide wastewater treatment: three-dimensional packed-bed electrochemical oxidation and biological contact degradation

2013 ◽  
Vol 68 (1) ◽  
pp. 257-260 ◽  
Author(s):  
Yujie Feng ◽  
Junfeng Liu ◽  
Limin Zhu ◽  
Jinzhi Wei
Keyword(s):  
Electrochemical Oxidation ◽  
Organic Contaminants ◽  
Removal Rate ◽  
Three Dimensional ◽  
Oxygen Demand ◽  
Cell Voltage ◽  
Packed Bed ◽  
Cod Removal ◽  
Cod Removal Rate ◽  
Oxidation Reactor

The clomazone herbicide wastewater was treated using a combined technology composed of electrochemical catalytic oxidation and biological contact degradation. A new type of electrochemical reactor was fabricated and a Ti/SnO2 electrode was chosen as the anode in electrochemical-oxidation reactor and stainless steel as the cathode. Ceramic rings loaded with SnO2 were used as three-dimensional electrodes forming a packed bed. The operation parameters that might influence the degradation of organic contaminants in the clomazone wastewater were optimized. When the cell voltage was set at 30 V and the volume of particle electrodes was designed as two-thirds of the volume of the total reactor bed, the chemical oxygen demand (COD) removal rate could reach 82% after 120 min electrolysis, and the ratio of biochemical oxygen demand (BOD)/COD of wastewater increased from 0.12 to 0.38. After 12 h degradation with biological contact oxidation, the total COD removal rate of the combined technology reached 95%, and effluent COD was below 120 mg/L. The results demonstrated that this electrocatalytic oxidation method can be used as a pretreatment for refractory organic wastewater before biological treatment.

scholarly journals Study on Anodic Oxidation parameters for removal of pesticide Imidacloprid on a modified tantalum surface by lead dioxide film

2020 ◽  
Keyword(s):  
Current Density ◽  
Crop Production ◽  
Ph Value ◽  
Lead Dioxide ◽  
Oxygen Demand ◽  
Electrochemical Process ◽  
Order Kinetic ◽  
Initial Ph ◽  
Transport Control ◽  
Dioxide Film

<p>The commercial imidacloprid (IMD) insecticide [1-(6-chloro-3-pyridinyl) methyl-4,5-dihydro-N-nitro-1H-imidazole-2-amine] is widely used for the enhancement of crop production, but the intensive use of this insecticide has caused serious environmental problems. This work presents an electrochemical process for the removal of this insecticide using galvanostatic electrolysis at modified tantalum surface by lead dioxide film anode (Ta(PbO2)) anode. The electrolytic process was monitored by chemical oxygen demand (COD). The influence of operating parameters, such as current density, initial concentration of IMD, temperature and initial pH value was investigated. The COD decay follows a pseudo first-order kinetic and the process was under mass transport control. COD removal reach 97% when using an apparent current density of 100 mA cm−2, initial COD of 953 mg L−1 and at 25 °C after 4.5 h electrolysis time.</p>

scholarly journals Electrochemical Degradation of Crystal Violet Using Ti/Pt/SnO2 Electrode

2021 ◽  
Vol 11 (18) ◽  
pp. 8401
Author(s):  
Rachid El Brychy ◽  
Mohamed Moutie Rguiti ◽  
Nadia Rhazzane ◽  
Moulay Driss Mellaoui ◽  
Khalid Abbiche ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Crystal Violet ◽  
Current Density ◽  
Ph Value ◽  
Supporting Electrolyte ◽  
Chloride Concentration ◽  
Oxygen Demand ◽  
Electrochemical Treatment ◽  
Electrochemical Process ◽  
Initial Ph

Today, organic wastes (paints, pigments, etc.) are considered to be a major concern for the pollution of aqueous environments. Therefore, it is essential to find new methods to solve this problem. This research was conducted to study the use of electrochemical processes to remove organic pollutants (e.g., crystal violet (CV)) from aqueous solutions. The galvanostatic electrolysis of CV by the use of Ti/Pt/SnO2 anode, were conducted in an electrochemical cell with 100 mL of solution using Na2SO4 and NaCl as supporting electrolyte, the effect of the important electrochemical parameters: current density (20–60 mA cm−2), CV concentration (10–50 mg L−1), sodium chloride concentration (0.01–0.1 g L−1) and initial pH (2 to 10) on the efficiency of the electrochemical process was evaluated and optimized. The electrochemical treatment process of CV was monitored by the UV-visible spectrometry and the chemical oxygen demand (COD). After only 120 min, in a 0.01mol L−1 NaCl solution with a current density of 50 mA cm−2 and a pH value of 7 containing 10 mg L−1 CV, the CV removal efficiency can reach 100%, the COD removal efficiency is up to 80%. The process can therefore be considered as a suitable process for removing CV from coloured wastewater in the textile industries.

scholarly journals Effect of compressive force on the performance of a proton exchange membrane fuel cell

2007 ◽  
Vol 221 (9) ◽  
pp. 1067-1074 ◽  
Author(s):  
T Ous ◽  
C Arcoumanis
Keyword(s):  
Fuel Cell ◽  
Mass Transport ◽  
Current Density ◽  
Proton Exchange Membrane ◽  
Compressive Force ◽  
Cell Voltage ◽  
Proton Exchange ◽  
Excessive Pressure ◽  
Transport Region ◽  
Exchange Membrane

The effect of the compressive force on the performance of a proton exchange membrane fuel cell has been examined experimentally. The performance has been evaluated on two polarization regions of the cell: ohmic and mass transport. Cell voltage and current density as a function of pressure were measured under constant load and various inlet air humidity conditions. The pressure distribution on the surface of the gas diffusion layer was measured using a pressure detection film and the results show that increasing the pressure improves the performance of the cell. The improvement of the cell voltage in the ohmic region was found to be greater than that in the mass transport region, whereas for the cell current density, the mass transport region exhibited higher change. The increase in the cell specific power in the ohmic and mass transport regions, as pressure increases from 0 to 2MNm-2, is estimated to be 9 and 18mWcm−2, respectively. However, the fuel cell performance in these two regions declined dramatically when excessive pressure (≥5 MNm−2) was applied. The mass transport region proved to be more susceptible to this sharp decline under excessive pressure than the ohmic region.

Electrochemical treatment and operating cost analysis of textile wastewater using sacrificial iron electrodes

2009 ◽  
Vol 60 (9) ◽  
pp. 2261-2270 ◽  
Author(s):  
M. Kobya ◽  
E. Demirbas ◽  
A. Akyol
Keyword(s):  
Current Density ◽  
Batch Reactor ◽  
Operating Cost ◽  
Oxygen Demand ◽  
Textile Wastewater ◽  
Iron Electrode ◽  
Treated Wastewater ◽  
Experimental Conditions ◽  
Potential Measurement ◽  
Initial Ph

Electrocoagulation (EC) method with iron electrode was used to treat the textile wastewater in a batch reactor. Iron electrode material was used as a sacrificial electrode in monopolar parallel mode in this study. The removal efficiencies of the wastewater by EC were affected by initial pH of the solution, current density, conductivity and time of electrolysis. Under the optimal experimental conditions (initial pH 6.9, current density of 10 mA/cm2, conductivity of 3,990 μS/cm, and electrolysis time of 10 min), the treatment of textile wastewater by the EC process led to a removal capacity of 78% of chemical oxygen demand (COD) and 92% of turbidity. The energy and electrode consumptions at the optimum conditions were calculated to be 0.7 kWh/kg COD (1.7 kWh/m3) and 0.2 kgFe/kg COD (0.5 kgFe/m3), respectively. Moreover, the operating cost was calculated as 0.2 €/kg removed COD or 0.5 €/m3 treated wastewater. Zeta potential measurement was used to determine the charge of particle formed during the EC which revealed that Fe(OH)3 might be responsible for the EC process.

scholarly journals Optimization of guava juice wastewater electrochemical treatment

2021 ◽  
Vol 10 (2) ◽  
pp. e41910212474
Author(s):  
Gilmar dos Santos ◽  
Joel Marques da Silva ◽  
Javier Alonso Villegas-Aragón ◽  
Silvanio Silvério Lopes da Costa ◽  
Joel Alonso Palomino-Romero
Keyword(s):  
Current Density ◽  
Aluminum Sulfate ◽  
Treatment Time ◽  
Electricity Consumption ◽  
Oxygen Demand ◽  
Electrochemical Treatment ◽  
Cod Removal ◽  
Electrochemical Processes ◽  
Initial Ph ◽  
Consumption Rates

Wastewater from guava juice production was treated by two electrochemical processes: Electroflotation (EF) and Electrocoagulation (EC). Using Box-Behnken experimental design, these processes were optimized in order to find the values of treatment time, initial pH and current density that lead to the maximum chemical oxygen demand (COD) removal efficiencies. Aluminum electrodes were used in EC treatment and an iron cathode and a ruthenium dioxide / titanium dioxide anode were applied in EF treatment. EC treatment resulted in maximum COD removal of 60%, when treating the wastewater for 40 minutes, with initial pH 4.5 and current density of 35 A/m2. On the other hand, EF only removed 25% of the wastewater COD (treatment time 40 minutes, initial pH 7.0 and current density 45 A/m2). Aluminum sulfate addition improved the wastewater conductivity, lowering electricity consumption rates. Moreover, the treatment combining EF and this chemical coagulant lead to better results than the ones found when using EF alone.

scholarly journals Anodic oxidation of synthetic refinery effluent on lead anode: mass transport and charge rate balance

2021 ◽  
Author(s):  
T. Zier ◽  
S. Bouafia-Chergui ◽  
M. Chabani
Keyword(s):  
Energy Consumption ◽  
Mass Transport ◽  
Anodic Oxidation ◽  
Current Density ◽  
Supporting Electrolyte ◽  
Electric Energy ◽  
Oxygen Demand ◽  
Cod Removal ◽  
Synthetic Wastewater ◽  
Charge Rate

Abstract A synthetic wastewater based on Algiers refinery real effluent was prepared and treated using anodic oxidation. Full factorial plan design was used to conduct the statistical analysis of the results. The aim of the study was to assess the interaction between current density (CD) and stirring degree (SD), and quantify their effects on chemical oxygen demand (COD) removal and electric energy specific consumption (EESC). With an initial COD of 487 mg/l, pH of 5.5 and 0.05 M of Na2SO4 as supporting electrolyte, it was found that a 55 rpm steering degree variation lead to a substantial gain in COD removal and energy consumption, 6% and 8.5 KWh/kg, respectively. Current density was found to have different effect on removal efficiency within the applied stirring domain, and that mass transport coefficient (km) is inversely correlated to energy consumption. Theoretical model describing the process was reviewed and the relation between concentration, hydrodynamics and applied current was emphasized.

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