Electrochemical Removal Cyanide in Wastewater by Ti/RuO2-Pt Electrodes

2014 ◽  
Vol 955-959 ◽  
pp. 2290-2293
Author(s):  
Chang Hang Wu
Keyword(s):  
Removal Efficiency ◽  
Current Density ◽  
Chloride Ion ◽  
High Energy ◽  
Electrolytic Cell ◽  
Direct Oxidation ◽  
High Concentration ◽  
Electrode Distance ◽  
Pt Electrodes ◽  
Operating Current

A laboratory-scale electrolytic cell with a Ti/RuO2-Pt anode and a Ti cathode was developed to treat high concentration cyanide-contained wastewater. The effects of the different electrode distances, concentration of chlorine anion and current densities, on the CN- removal were investigated. The results shown the too short and long electrode distance resulted in high energy consumption and low current, the appropriate electrode distance was essential. The CN- removal was very significant at the electrode distance was 9 cm, and the removal efficiency reached 99.2%. The removal CN- electrochemical oxidation was mainly attributed the success to in direct oxidation effect of chlorine /hypo-chlorite produced during the electrochemical reaction process. The CN- removal efficiency increased with increasing the concentration of chloride ion and operating current density. The optimum experimental condition was set at the electrode distance of 9 cm, NaCl dosage of 0.5 g/L, the current density of 10 mA/cm2, and pH of 12. At the optimum experimental condition, the CN- concentration in the solution decreased from 150.33 mg/L to 1.20 mg/L, and the CN- removal efficiency reached 99.2%.

Study on Advanced Pretreatment of Seawater by Electrolysis and Neutralization of Acidic Waste Water with By-Product Magnesium Hydroxide

2013 ◽  
Vol 821-822 ◽  
pp. 1071-1080
Author(s):  
Jing Nie ◽  
Shou Zhi Yi ◽  
Di Miao
Keyword(s):  
Removal Efficiency ◽  
Magnesium Hydroxide ◽  
Current Density ◽  
Industrial Wastewater ◽  
Removal Rate ◽  
Influence Factors ◽  
Operation Time ◽  
Wastewater Discharge ◽  
Electrode Distance

The advanced pretreatment by electrolysis of Bohai seawater in Tianjin used a diaphragm electrolyzer in the experiment. Removal efficiency and influence factors of the method were analyzed. Results show that turbidity, organic compounds, SDI and chroma of seawater were effectively decreased by electrolysis. Removal efficiency was significantly increased by current density, operation time and inter-electrode distance, and the optimum electrolytic conditions was determined as inter-electrode distance of 2 cm, current density of 15.87 mA·cm-2, operation time of 10 minutes. It was investigated that when the water quality after electrolysis was of pH 8.6, the chroma and turbidity decreasing trend slowed down, with chroma of 0.052 A, removal rate reached 88.4%; the residual turbidity reduced to 2.52 NTU, removal rate reached 90.71%. A PH of about 8.5, CODCr decreasing trend slowed down, and when CODCr < 750 mg/L, it conformed to the requirements of the reverse osmosis water. With the study on neutralization of steel pickling waste liquor by the by-product of magnesium hydroxide, it is found that the quality of treated water reached 3rd level national emissions standards (300-1000 mg/L). Magnesium hydroxide slurry of Cr (VI) removal rate reached 100%, conforming to the 1st level national industrial wastewater discharge standards (< 0.5 mg/L).

Electrochemical Oxidation of the Effluent from Coking Wastewater Treatment Plants Using Ti/RuO2-IrO2 Electrode

2014 ◽  
Vol 587-589 ◽  
pp. 629-635 ◽  
Author(s):  
Jian Bing Wang ◽  
Chun Li Yang ◽  
Xue Jiao Duan ◽  
Tian Yue Wang ◽  
Ya Hua Wang ◽  
...  
Keyword(s):  
Electrochemical Oxidation ◽  
Removal Efficiency ◽  
Wastewater Treatment Plants ◽  
Volume Ratio ◽  
Chloride Ion ◽  
Ammonia Removal ◽  
Coking Wastewater ◽  
Electrode Distance ◽  
Better Than ◽  
Main Factor

This paper explored the electrochemical oxidation of coking wastewater with Ti/RuO2-IrO2anode. The effects of electrodes connections, area-volume ratio and aeration on the removal efficiency were studied and the ammonia removal mechanism was investigated. The results show that the highest NH4+-N and COD removal efficiency and current efficiency are achieved at the area-volume ratio of 14.44m2/m3and electrode distance of 0.5cm. Unipolar connection is better than bipolar connection. For electrochemical oxidation of ammonia, the chloride ion is the main factor affecting nitrogen removal. NH4+-N is removed mainly by the oxidation of hypochlorous.

scholarly journals Optimization of process parameters for the electrochemical oxidation treatment of petroleum refinery wastewater using porous graphite anode

2020 ◽  
Vol 13 (2) ◽  
pp. 125-135
Author(s):  
Ahmad Salah Fahim ◽  
Ali H. Abbar
Keyword(s):  
Removal Efficiency ◽  
Current Density ◽  
Petroleum Refinery ◽  
Oxygen Demand ◽  
Chloride Ion ◽  
Electrochemical Reactor ◽  
Electrochemical Treatment ◽  
Operating Conditions ◽  
Graphite Anode ◽  
Porous Graphite

The present paper deals with the electrochemical treatment of wastewaters generated from Al-Diwaniyah petroleum refinery plant in a batch electrochemical reactor using stainless steel cathode and porous graphite anode. Effects of operating parameters such as current density (5-25mA/cm2), pH (3-9), addition of NaCl (0-2g/l), and time (20–60min) on the removal efficiency of chemical oxygen demand (COD) were investigated. The results revealed that both pH and NaCl addition have the main effect on the COD removal efficiency confirming that the system was governed by reaction conditions in the bulk of solution not upon the electro oxidation of chloride ion on the surface of the electrode. Parametric optimization was carried out using Response Surface Methodology (RSM) combined with Box–Behnken Design (BBD) to maximize the removal of COD. Under optimized operating conditions of initial pH: 3, current density = 25 mA/cm2, NaCl conc.  = 2g/l, and time = 60 min, the removal efficiency of COD was found to be 98.16% with energy consumption of 9.85 kWh/kgCOD which is relatively lower than the previous works.

scholarly journals Decomposition of gas phase benzene under different conditions in atmospheric strong ionization non–thermal plasma

2020 ◽  
Vol 2 (2) ◽  
pp. 22-29
Author(s):  
Prince Junior Asilevi ◽  
Chengwu Yi ◽  
Jue Li ◽  
Huijuan Wang ◽  
Muhammad Imran Nawaz
Keyword(s):  
Removal Efficiency ◽  
Current Density ◽  
High Energy ◽  
Ring Cleavage ◽  
Oh Radicals ◽  
Test Results ◽  
High Energy Electrons ◽  
Study Results ◽  
Key Species ◽  
Specific Input Energy

Atmospheric volatile organic compounds (VOCs) from industry and automobiles are posing a serious threat to the environment and human health, and hence efficient control methods are indispensable. This paper presents a laboratory-scale study on the decomposition mechanism for benzene using strong ionization dielectric barrier discharge (DBD) at atmospheric pressure. The specific input energy (SIE), current density, and concentration were studied. The results show that the removal efficiency of benzene increased from 12% to 69% with the increase of SIE from 0.5 to 3.8 kJ/L. The decline in current density by 66.48% and 43.7% for an initial benzene concentration of 300 ppm, was due to increased oxygen content (from 2.4% to 20.9%) and relative humidity (from 18.9% to 90%), respectively, thus electron concentration and consequentially enhancing the removal efficiency over 93%. Further, the beta parameter of the VOC decomposition law decreased from 3.1 kJ/L at 300 ppm to 1.6 kJ/L at 100 ppm. This shows that •O and •OH radicals are key species for the decomposition of benzene and electron dissociation reactions principally control the process. The highest ozone concentration was detected at 5.5 mg/L when no benzene is present, while the main NOx species (NO and NO2) increased with increasing SIE. The Maxwell–Boltzmann electron energy distribution function was solved using the strong ionization discharge reactor (~10 eV), showing that approximately 84.8 % of high-energy electrons possess enough energy to cause the benzene ring cleavage and free radical production. Finally, GCMS and FTIR test results suggested that the byproducts mainly consisted of phenol and substitutions of phenol. The study results show that the strong ionization DBD reactor efficiently removes benzene from polluted air.

Treatment of Wastewater Containing High Concentration Ammonia-Nitrogen by Electrochemical Oxidation Process

2011 ◽  
Vol 393-395 ◽  
pp. 1587-1590
Author(s):  
Ya Feng Li ◽  
Yuan Han Duan
Keyword(s):  
Total Nitrogen ◽  
Current Density ◽  
Oxidation Process ◽  
Chloride Ion ◽  
Chemical Oxidation ◽  
Ammonia Nitrogen ◽  
Ion Concentration ◽  
High Concentration ◽  
Initial Ph ◽  
Plate Distance

The simulant wastewater containing high concentration ammonia-nitrogen was treated by electro-chemical oxidation process in intermittent experiment. The influences of different factors including plate distance,current density, chloride ion concentration and initial pH on ammonia-nitrogen and total nitrogen removal were studied.According to the results of the test, the optimal reaction condition was determined as follows: plate distance was 40mm，current density was 90mA/cm2，chloride ion concentration was 8000mg/L, initial pH was 10。Under the above condition,the total nitrogen concentration reduced from 2000 mg/Lto 280mg/L when the reaction time was 8h, and the removal rate reached 86%. As we can see, the effect of the treatment is quite positive.

Feasibility of an electrochemically assisted Fenton method using Fe2 +/HOCl system as an advanced oxidation process

2010 ◽  
Vol 62 (10) ◽  
pp. 2321-2329 ◽  
Author(s):  
N. Kishimoto ◽  
E. Sugimura
Keyword(s):  
Current Density ◽  
Degradation Rate ◽  
Hypochlorous Acid ◽  
Advanced Oxidation Process ◽  
High Current Density ◽  
Iron Concentration ◽  
Ferric Hydroxide ◽  
Chloride Ion ◽  
High Concentration ◽  
Stainless Steel Cathode

The feasibility of an electrochemically assisted Fenton treatment using a Fenton-type reaction of ferrous iron (Fe2 + ) and hypochlorous acid (HOCl) is discussed in this research. The reactor used was composed of an undivided single cell with a ruthenium dioxide-coated titanium anode and a stainless steel cathode, in which Fe2 +  and HOCl were catalytically regenerated from ferric iron at the cathode and chloride ion at the anode, respectively. Although the reactor functioned well, the degradation rate of 1,4-dioxane as a hydroxyl radical probe decreased at the current density more than 6.92 mA cm−2. The decrease in degradation rate was inferred to be caused by the vain consumption of hydroxyl radicals by excess HOCl and the deposition of ferric hydroxide on the cathode at relatively high current density. The current efficiency of 1,4-dioxane removal remained more than 90% at the current density less than 6.92 mA cm−2 and the iron concentration not less than 1.0 mmol L−1. Consequently, this technique is thought to be applicable to the treatment of wastewater containing high concentration of chloride ion such as landfill leachate, scrubber wastewater from incineration plants, etc.

Study on Advanced Pretreatment of Seawater by Electrolysis

2014 ◽  
Vol 881-883 ◽  
pp. 598-603
Author(s):  
Jing Nie ◽  
Shou Zhi Yi ◽  
Di Miao
Keyword(s):  
Water Quality ◽  
Reverse Osmosis ◽  
Organic Compounds ◽  
Removal Efficiency ◽  
Current Density ◽  
Removal Rate ◽  
Influence Factors ◽  
Operation Time ◽  
Electrode Distance

The advanced pretreatment by electrolysis of Bohai seawater in Tianjin used a diaphragm electrolyzer in the experiment. Removal efficiency and influence factors of the method were analyzed. Results show that turbidity, organic compounds, SDI and chroma of seawater were effectively decreased by electrolysis. Removal efficiency was significantly increased by current density, operation time and inter-electrode distance, and the optimum electrolytic conditions was determined as inter-electrode distance of 2 cm, current density of 15.87 mA·cm-2, operation time of 10 minutes. It was investigated that when the water quality after electrolysis was of pH 8.6, the chroma and turbidity decreasing trend slowed down, with chroma of 0.052 A, removal rate reached 88.4%; the residual turbidity reduced to 2.52 NTU, removal rate reached 90.71%. A PH of about 8.5, CODCr decreasing trend slowed down, and when CODCr < 750 mg/L, it conformed to the requirements of the reverse osmosis water.

Enhanced Ion Transport in an Ether Aided Super Concentrated Ionic Liquid Electrolyte for Long-Life Practical Lithium Metal Battery Applications

2020 ◽  
Author(s):  
Urbi Pal ◽  
Fangfang Chen ◽  
Derick Gyabang ◽  
Thushan Pathirana ◽  
Binayak Roy ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Ion Transport ◽  
Current Density ◽  
Coulombic Efficiency ◽  
High Energy ◽  
Liquid Electrolyte ◽  
High Mass ◽  
Lithium Metal ◽  
Ionic Liquid Electrolyte ◽  
Lithium Metal Battery

We explore a novel ether aided superconcentrated ionic liquid electrolyte; a combination of ionic liquid, <i>N</i>-propyl-<i>N</i>-methylpyrrolidinium bis(fluorosulfonyl)imide (C<sub>3</sub>mpyrFSI) and ether solvent, <i>1,2</i> dimethoxy ethane (DME) with 3.2 mol/kg LiFSI salt, which offers an alternative ion-transport mechanism and improves the overall fluidity of the electrolyte. The molecular dynamics (MD) study reveals that the coordination environment of lithium in the ether aided ionic liquid system offers a coexistence of both the ether DME and FSI anion simultaneously and the absence of ‘free’, uncoordinated DME solvent. These structures lead to very fast kinetics and improved current density for lithium deposition-dissolution processes. Hence the electrolyte is used in a lithium metal battery against a high mass loading (~12 mg/cm<sup>2</sup>) LFP cathode which was cycled at a relatively high current rate of 1mA/cm<sup>2</sup> for 350 cycles without capacity fading and offered an overall coulombic efficiency of >99.8 %. Additionally, the rate performance demonstrated that this electrolyte is capable of passing current density as high as 7mA/cm<sup>2</sup> without any electrolytic decomposition and offers a superior capacity retention. We have also demonstrated an ‘anode free’ LFP-Cu cell which was cycled over 50 cycles and achieved an average coulombic efficiency of 98.74%. The coordination chemistry and (electro)chemical understanding as well as the excellent cycling stability collectively leads toward a breakthrough in realizing the practical applicability of this ether aided ionic liquid electrolytes in lithium metal battery applications, while delivering high energy density in a prototype cell.

scholarly journals Start-up Strategies for Anaerobic Ammonia Oxidation (Anammox) in In-Situ Nitrogen Removal from Polluted Groundwater in Rare Earth Mining Areas

2021 ◽  
Vol 13 (8) ◽  
pp. 4591
Author(s):  
Shuanglei Huang ◽  
Daishe Wu
Keyword(s):  
Rare Earth ◽  
Low Temperature ◽  
Removal Efficiency ◽  
Nitrogen Removal ◽  
Ex Situ ◽  
High Concentration ◽  
Low Concentration ◽  
Start Up ◽  
Anammox Activity

The tremendous input of ammonium and rare earth element (REE) ions released by the enormous consumption of (NH4)2SO4 in in situ leaching for ion-adsorption RE mining caused serious ground and surface water contamination. Anaerobic ammonium oxidation (anammox) was a sustainable in situ technology that can reduce this nitrogen pollution. In this research, in situ, semi in situ, and ex situ method of inoculation that included low-concentration (0.02 mg·L−1) and high-concentration (0.10 mg·L−1) lanthanum (La)(III) were adopted to explore effective start-up strategies for starting up anammox reactors seeded with activated sludge and anammox sludge. The reactors were refrigerated for 30 days at 4 °C to investigate the effects of La(III) during a period of low-temperature. The results showed that the in situ and semi in situ enrichment strategies with the addition of La(III) at a low-concentration La(III) addition (0.02 mg·L−1) reduced the length of time required to reactivate the sludge until it reached a state of stable anammox activity and high nitrogen removal efficiency by 60–71 days. The addition of La(III) promoted the formation of sludge floc with a compact structure that enabled it to resist the adverse effects of low temperature and so to maintain a high abundance of AnAOB and microbacterial community diversity of sludge during refrigeration period. The addition of La(III) at a high concentration caused the cellular percentage of AnAOB to decrease from 54.60 ± 6.19% to 17.35 ± 6.69% during the enrichment and reduced nitrogen removal efficiency to an unrecoverable level to post-refrigeration.

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