Electrochemical Incineration of Glucose as a Model Organic Substrate. II. Role of Active Chlorine Mediation (original) (raw)
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Water, 2020
A short review on the treatment of effluents from food processing industries by electrochemical oxidation (EO) was performed. Olive mill wastewater (OMW) and boron-doped diamond (BDD) are the most reported effluent and anode material, respectively. The addition of NaCl or Na2SO4 as supporting electrolytes is common in these studies, and their influence on the EO performance depends, among other things, on the anode material, since the electrolyte oxidation mechanism is different when active and non-active anode materials are utilized. A case-study on the application of a pilot plant, working in batch mode with recirculation, equipped with a BDD anode, to treat 4 L of OMW, slaughterhouse (SW) and winery (WW) wastewaters, with initial chemical oxygen demands (COD) of 20.5, 3.6 and 0.26 g L−1, respectively, is presented and discussed. In 16 h assays, 94% COD removal was achieved for OMW, and for SW and WW the Portuguese COD legal discharge limit of 150 mg L−1 was accomplished. Process ...
Electrochemical oxidation of organic pollutants at low electrolyte concentrations
2000
The electrochemical oxidation of organic pollutants is a promising process for substances which are recalcitrant to biological degradation. The anodic oxidation of coumaric acid, which is a biorefractory organic pollutant of olive oil manufacturing waste waters, was evaluated on a Pt-Ti electrode. The operating test conditions were compatible with direct discharge of the after-treatment effluent in natural water basins or rivers as regards the electrolyte salt content (Na 2 SO 4 =0.02 N). The effect of the applied current density, pH, temperature, initial coumaric acid concentration and of the type of DC feeder (a galvanostat or a simple current rectifier) over the oxidation rate was assessed through a series of batch runs performed in a pilot plant apparatus. Beyond direct oxidation at the Pt-electrode surface, bulk oxidation with hydrogen peroxide, generated through a persulfate-formation/hydrolysis route, was found to be a crucial step in coumaric acid degradation to more biodegradable non-aromatic products. Small quantities of Fe ions were helpful in accelerating the oxidation process. An analysis of the rather complex reaction schemes governing the process is proposed.
Chemical Society Reviews, 2006
In recent years, there has been increasing interest in finding innovative solutions for the efficient removal of contaminants from water, soil and air. The present tutorial review summarizes the results of an extensive selection of papers dealing with electrochemical oxidation, which is proposed as an alternative for treating polluted wastes. Both the direct and indirect approaches are considered, and the role of electrode materials is discussed together with that of other experimental parameters.
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.
Treatment of organic content at high Total Dissolved Solids By Electrochemical Oxidation
IJSRD, 2014
The electrochemical treatment of synthetic wastewater with salinity of 330 g NaCl/L and organic load of up to 3200 mg COD/L was investigated. The effects of important parameters like pH, temperature, potential, current, reaction time, and initial organic concentration were studied using graphite electrodes. Tween80 and phenol were used as organic pollutants for the preparation of the synthetic wastewater. The best reduction in COD was observed at pH 6.0 for phenol and 6.4 for tween80, temperature of 10°C, potential of 4.0V(tween80) and 3.0V(phenol), current of 0.2A(tween80) and 0.3A(phenol), and reaction time of 60 minutes. The variations were depicted using State-Ease® Design Expert software trail version 8.0.6 and response surface methodology (RSM). Total current efficiency (TCE), anode efficiency (AE) and energy consumption (EC) were also most desirable at these optimum conditions. Reaction kinetics reveal that the electro-oxidation here follow the pseudo-first-order model. Negative values of ΔSº and ΔHº for both phenol and tween80 indicate that at lower temperatures the reaction is feasible and spontaneous so as to make ΔGº negative. Using these optimized parameters, significant reduction in COD of up to 100% was achieved in a real saline wastewater with COD of up to 1100 mg/L.
Electrochemical Treatment of Industrial Organic Effluents
CHIMIA, 1995
The anodic oxidation of organics is a potentially powerful technique of controlling pollutants in industrial waste waters. Based on a fundamental analysis, this paper summarizes recent results in this field. Direct electrochemical processes catalyzed by the oxygen-transfer reaction are discussed for several anode materials. Ti/SnO2 is particularly efficient for cold combustion of aromatic pollutants. Potential candidate processes involving the electrochemical generation of oxidizer reactants (O3, H2O2), or the electrochemical regeneration of metallic redox couples are discussed.
Electrochemical Oxidation of Industrial Waste Water after Secondary Treatment
2018
In recent years, there has been increasing interest in finding innovative solutions for the efficient removal of contaminants from water, soil and air. Electrochemical oxidation has gained increasing interest due to its outstanding technical characteristics for eliminating a wide variety of pollutants normally present in waste-waters such as refractory organic matter, nitrogen species and microorganisms. Effluents from landfill and a wide diversity of industrial effluents including the agro-industry, chemical, textile, tannery and food industry, have been effectively treated by this technology. Here we will deal with the process of electrochemical oxidation, which is proposed as an alternative for treating polluted waste water. We will be focusing on reduction of the COD of the industrial waste water after secondary treatment.
Electrochemical oxidation of wastewater – opportunities and drawbacks
Water Science and Technology, 2013
Electrochemical oxidation by means of boron-doped diamond (BDD) anodes generates a very efficient oxidizing environment by forming hydroxyl radicals, providing effective water purification for elimination of persistent pollutants. In this project the degradation rates of organic and inorganic substances are investigated. Experiments were performed in laboratory and pilot scale with synthetic and industrial wastewaters. Performance parameters were evaluated in terms of total organic carbon/chemical oxygen demand (COD) removal, specific energy consumption and current efficiency. The integration of this advanced oxidation technology combined with conventional technology was then applied in a wastewater treatment concept of landfill leachate. The raw leachate with a low biochemical oxygen demand/COD ratio was electrochemically oxidized to prepare the purified leachate for discharge into a sewage system or a receiving water body. The cost estimation regarding operation and capital costs ...
Remediation of domestic wastewater by electrochemical oxidation of dissolved organic species
Journal of the Iranian Chemical Society, 2020
This study reports on the treatment of wastewater containing dissolved organic matter (DOM). DOM introduces complexing agents, promotes bacterial growth, and affects the color plus taste of water negatively. The normal practice for treatment such pollutants is the use of introduction of oxidizing agents in the water. However, this introduces secondary pollutants to the treated water, and to overcome the challenge, this study has developed an electrochemical method for treating wastewater with no secondary pollutants. A two-chamber electrochemical cell separated by a proton exchange membrane (PEM) was constructed with inert electrodes. The PEM was made from a conducting polymer inert in aqueous media. The anode water was bubbled with air for reduction of oxygen and therefore formation of strong oxidizing agent for the degradation of DOM. The degradation was monitored using Ultraviolet-visible (UV-VIS) spectroscopy as the potential difference across the cell was monitored. There was a significant reduction in the color and the decay followed first-order kinetics, for unimolecular degradation with a constant of 0.0148 min −1. A high potential of 1.25 V was registered within the first 40 min confirming that the degradation was spontaneous making the water safe for consumption. The degradation was confirmed by voltametric method where the concentration of iron within the vegetative matter was observed to increase at a potential of − 0.18 V with time due to the release of the labile metal ions. This shows that the constructed cell has a potential application in the remediation of domestic wastewater at a point of use.
Modern Water Treatment by Electrochemical Oxidation - a Review
2013
Electrochemical oxidation (EO) as electrochemical method is unique by three aspects. The first is that is the most versatility process in water treatment area and covers: various industrial effluent treatment including, amongst others, distillery, agrochemical, pulp and paper, textile dyes, oilfield and metalplating wastes; hazardous effluent treatment including hospital wastes; removal of pathogens and persistent, pharmaceutical residues and biological from municipal wastewater treatment plant; removal of organic micro-pollutants such as pesticides and heavy metals such as arsenic and chromium from water. Another aspect is that EO is complementary with most other methods: chemical or electrochemical, and is often combined with one or more of them. And finally, this procedure is the most interdisciplinary of all. It includes: material science, (micro)biology, (electro)chemistry, environmental protection, water supply systems, etc.