Electrochemical Treatment Research Articles

Integrating natural tourmaline with energy conversion ability to magnetically assembled electrode: Boosted electrochemical oxidation wastewater treatment performance

Novel anodes are desirable in the development of electrochemical oxidation wastewater treatment (EOWT). Magnetically assembled electrode (MAE) is a novel modular electrode format that physically adsorbs magnetic particles (auxiliary electrodes, AEs) onto the main electrode (ME) by magnetic force which realizes an effective and sustainable EWOT process but puts a new requirement on AEs polarization. Therefore, tourmaline (Tml), a natural mineral with ferroelectricity, pyroelectricity, and piezoelectricity, was introduced into the MAE in this study. Tml particles were expected to utilize waste heat or mechanical energies in electrolysis (e.g., Joule heat, bubble strike) and give extra electricity to the stacked AEs (Fe3O4/Sb-SnO2 granules herein) to fully active MAE. Tml’s effects were investigated via different MEs (Ti/IrO2-Ta2O5, graphite, Ti/Sb-SnO2), different wastewater, different Tml sizes, loading amounts, and different conditions (e.g., current density). Results show that all these conditions could affect the buffering of Acid red G degradation, Tml could offer a 10∼40% buff. Medium Tml size and loading as well as low or medium current density (e.g., 2 mA·cm−2 or 20 mA·cm−2) are appropriate. For real wastewater degradation, Tml facilitates macromolecule destruction. This study may start a new application route of abundant natural energy-converting materials in the EOWT area.

Joining of Polymer to Aluminum Alloy AA1050 By Friction Spot Welding

The friction spot welding process is used to join the hybrid joint of aluminium to polymer. AA 1050 Aluminum alloy and polyethylene polymer (type of plastic) were used for joining. Aluminium surface treatment was done to increase the wettability of it. The surface treatment was done by electrochemical treatment. Two parameters of the joining process were used: (1, 1.5 and 2) min. (920, 1340 and 1500) rpm for time and rotational speed, respectively. Many tests for the joint are done: shear test and Scanning electron microscopy (SEM). Using the Minitab program, the effect of the parameters on the joint was analysed. The maximum value of the shear force was (1587 N) at 1.5 min. time and 1340 rpm rotational speed. The minimum shear force was (589 N) at 1 min. time and 920 rpm rotational speed. The joints which were tested failed by an interfacial shear with a ductile fracture of the polymer side. The process of joining mechanism occurred through a mechanical interlocking between the molten polymer and the surface of the AA 1050 aluminium specimen, cohesive and adhesive. The average thickness for the joint of the tested specimens was 4µm.

Electrochemical surface functionalization engineering of carbon cloth for ultrasensitive electrochemical detection of nitrite

In this work, the commercial carbon cloth modified with a large number of oxygen-containing functional groups (C-OH, COOH and CO) was fabricated by simple constant current electrochemical treatment (EFCC electrode) for the ultrasensitive electrochemical detection of nitrite. Due to the combination of enhanced superhydrophilicity, significantly improved conductivity and dramatically increased active specific surface area and sites, the EFCC electrode exhibited excellent nitrite detection performance, including wide detection ranges of 0.1–3500 μM divided into three ranges, low detection limit of 0.016 μM (S/N = 3) and ultra-high sensitivities of 12310, 3515, 1877 μA mM−1 cm−2. This work provided an important reference for the application of functionalized modification strategies to construct high-performance electrochemical sensors.

Increase of twinning stress in single crystalline Ni-Mn-Ga micropillars

We have investigated the effect of characteristic size decrease on the magneto-mechanical properties of Ni-Mn-Ga single crystalline 10M martensite, using micropillars prepared by focused-ion-beam milling. Following the electro-chemical surface treatment, the twinning stress in a focused-ion-beam milled micropillar with a characteristic size of about 17 µm was reduced from 17 MPa to below 2 MPa, allowing the magnetically induced reorientation of twin variants. We found that twinning stress universally increases with the decrease of characteristic size. In combination with the data for bulk material, our results suggest a power law dependence of twinning stress on characteristic size, with an exponent of -0.5 for both Type I and Type II single twin boundaries. Extrapolation of the fit suggests the characteristic size limit for magnetically induced reorientation to be 30 µm and 2 µm for Type I and Type II twin boundaries, respectively.

Electrochemical Treatment of Reactive Orange 16 Dye Pollutant Using Microbial Fuel Cell as Renewable Power Source

Electrochemical Treatment of Reactive Orange 16 Dye Pollutant Using Microbial Fuel Cell as Renewable Power Source

Research on the treatment of heavy metal ions by immobilized microbial technology

With the development of human industry, the mining and utilization of heavy metals has become more and more extensive, especially in the past 200 years. However, the excessive discharge of industrial and domestic sewage, overuse of pesticides and fertilizers in the production process, as well as electronic waste and medical waste in human life have led to many heavy metal ions entering the environment, exceeding the environmental capacity and entering organisms in large quantities, threatening the ecosystem and human health. Therefore, how to economically and efficiently deal with the heavy metal ion pollution generated in the process of production and life has become a hot issue. Currently, the main methods for treating heavy metal ions are chemical precipitation, ion exchange, adsorption, membrane filtration, electrochemical treatment technology, etc. However, the traditional methods for heavy metal treatment are usually faced with the problems of high cost, high complexity and high energy consumption. In recent years, microbial immobilization technology has received wide attention for its advantages of improved microbial stability, high heavy metal ion removal rate, etc. The corresponding microorganisms are encapsulated and aggregated by immobilized carriers, which enhances the cellular bioburden capacity and environmental resistance and improves the microbial removal efficiency of heavy metals.

Elucidation of Surface Functional Groups Deposited by Electrochemical Surface Treatment of Discontinuous Carbon Fiber by NEXAFS and XPS.

Control of carbon fiber heteroatom (oxygen and nitrogen) functionalization using electrochemical oxidation is explored in a variety of electrolyte solutions. Results of X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy indicate that most electrolytes in aqueous and anodic conditions are limited to heteroatom surface content of no more than 13 atomic percent (at %) with a majority C-O and/or C-N moieties; the remaining moieties include an oxidative sequence of carbon (alcohol to ketone to carboxylate) and more complex O- and N-containing groups. The pH of the electrolyte solution was found to be crucial in controlling the ratio of the amount of oxygen to nitrogen functionalities, with the increased basicity of solution resulting in higher nitrogen deposition. The oxidative (and/or thermal) decomposition of many electrolytes during electrochemical treatment can have a major impact on functionalization through changes to pH. Oxidation of carbon fiber in some electrolyte solutions showed higher surface concentrations of heteroatoms (25-30 at %) than most electrolytes (13 at %). Mechanisms were proposed to explain how some electrolytes can exceed 13 at % of heteroatom deposition. Specifically, we hypothesized that electrolytes that contain organic ions with chelation capabilities and moieties that produce additional sites of functionalization can overcome that threshold.

Evaluation of detrimental effects in concrete specimens due to the oxidation of sulfide-bearing aggregates after electrochemical treatment

Sulfide-bearing aggregates can cause significant damage when concrete has been produced without considering their potential deleterious oxidation reactivity. This study aims to find a reliable quantitative approach for assessing the impact of the harmful reaction of sulfide minerals (essentially pyrrhotite) in concrete specimens produced under laboratory conditions. To achieve this objective, different parameters such as an electrochemical treatment have been applied over 14, 28, 35 and 56-day periods on a series of concrete specimens made in the laboratory with a reactive sulfide-bearing aggregate (MSK 0.9) and non-reactive aggregate (PKA) After the treatment, the concrete specimens were tested with different tools such as non-destructive (Ultrasonic Pulse Velocity), semi destructive (expansion, modulus of elasticity and stiffness damage test) and destructive (concrete polished section and compression) methods to evaluate the impact of the deleterious reaction of the sulfide-bearing aggregates. The results show that concrete with the reactive aggregate can lose a significant amount of its mechanical performance exhibited principally by a significant reduction in modulus of elasticity (decreasing around 28% after 35 days of electrochemical treatment). Signs of damage associated with the use of the MSK aggregate were identified within concrete polished sections and under the SEM, which allowed to better describe the mechanisms of the oxidation reaction of the sulfide minerals. Ideal parameters/conditions can be achieved to evaluate the potential oxidation reaction of sulfide-bearing aggregates using the electrochemical treatment and the reduction of the modulus of elasticity of the concrete in a reasonable period of time.

Electrochemical Recovery of Phosphorus from Simulated and Real Wastewater: Effect of Investigational Conditions on the Process Efficiency

The development of recovery processes has become essential in recent years as a strategy to minimize environmental pollution while boosting circular economy and sustainable development. Due to the exponential growth in agricultural production and the increased pollution of waterbodies, the production of fertilizers from recovered phosphorus has become an alternative to phosphate rock-based production. In this work, the effect of different operational parameters in the efficiency of the electrochemical recovery of phosphorus, from organic and inorganic sources, was investigated. Among the studied variables, the most significant was the electrode material utilized in the system. The use of magnesium sacrificial electrodes, as AZ31 alloys, led to phosphorus removal from solution of above 90%, allowing the recovery of both orthophosphates and organic phosphorus (glyphosate) as struvite, brucite, and other amorphous compounds. Since there is a lack in the literature about the use of magnesium electrodes in real wastewater electrochemical treatment, system efficiency was also evaluated using a sanitary landfill leachate, reaching 96% of phosphorus recovery. The specific energy consumption and faradaic efficiency of the phosphorus recovery process were also assessed.

Identification of the Chemical Components Derived from the Two‐Phase Electrocoagulation of Diesel Fuel

AbstractIn this study, two‐phase electrocoagulation (EC) approach was developed and used to investigate blend of bio‐diesel and petro‐diesel (B10) stability under the electrochemical treatment. Gas chromatography‐mass spectrometry (GC‐MS) was used to analyze the aliquots before and after the reaction. The major compounds were alkanes and aromatic compounds with the minor contents of aldehydes, ketones, esters, alkenes, alkynes, halogens, oxygenated compounds, and heterocyclic compounds. The selected condition for the reaction was 10 V and 60 min which resulted in 9.9×109 counts per s total peak area of compounds containing from nine to seventeen carbon atoms (C9 to C17) compared with 6.8×108 counts per s for the control. The peak areas of the straight chain alkanes increased from 12 % to 33 % of the total peak areas observed after the experiment. Compounds with higher peak areas were found between C12 to C14 with the retention indices range of 1155–1678. The EC treatment mainly increased the straight and branched alkane and alcohol contents with the decreasing contents of branched cyclic alkanes. The developed system could be adapted to study the stability of other types of fuels. This is cost effective and can be performed within an hour at room temperature under atmospheric pressure.

Electrochemical Treatment of the Surface of 12Kh18N10T Steel Parts Produced by Selective Laser Melting

Electrochemical Treatment of the Surface of 12Kh18N10T Steel Parts Produced by Selective Laser Melting

Sulphate-based electrochemical processes as an alternative for the remediation of a beauty salon effluent‡

Beauty salons (BS) are places that deal with a wide range of cosmetics with potentially hazardous chemicals, and their effluent should be properly treated before going to the sewage system, once it represents characteristics of industrial wastewater. This work provides an extensive characterization of a BS effluent and its respective electrochemical treatment by comparing NaCl, Na2SO4, and Na2S2O8 as supporting electrolytes with a boron-doped diamond (BDD) as anode, applying 10 or 30 mA cm−2 of current density (j). The inclusion of UVC irradiation was also performed but the improvements achieved in removing the organic matter were null or lower. The analysis of chemical oxygen demand (COD) removal, energy consumption, and total current efficiency (TCE) was required to prove the efficacy of the processes and the comparative study of the performance of different technologies. Precipitate analysis was also done due to the high turbidity of the raw effluent and the appearance of a precipitate before and during the electrolysis, mainly with Na2S2O8. The precipitate confirmed the presence of silicates and small amounts of heavy metals. The results clearly showed that 6 h of treatment with Na2SO4 achieved 58% of COD removal with an energy consumption of about 0.52 kWh m−3, being the best electrolyte option for treating BS effluent by applying 10 mA cm−2. Under these experimental conditions, the final wastewater can be directly discharged into the sewage system with a lower amount of visible precipitate, and with 73% less turbidity. The treatment here proposed can be used as an alternative to decision-makers and governments once it can be a step further in the implementation of better and advanced politics of water sanitation.

Cancer‐targeting carbon quantum dots synthesized by plasma electrochemical method for red‐light‐activated photodynamic therapy

AbstractCancer‐targeting carbon quantum dots (CQDs) with red‐light absorption/emission featuring inherent biological functionality and deep biological penetration depth are promising for biomedical applications. However, traditional high‐temperature and high‐pressure synthesis processes result in unpredictable functionalities and uncontrollable optical properties due to the functional group loss. Here, plasma electrochemical treatment is introduced to overcome this issue. The synthesized CQDs in this work have excellent folate receptor cancer‐targeting ability, red‐light absorption/emission, and pronounced photodynamic therapy effect. The CQDs produced by the plasma electrochemical method preserve most of the functional groups from precursors, thus making them to fully inherit the bio‐functionality and photophysical properties of precursors. This work opens new opportunities for plasma‐based processes to controllably synthesize functionalized CQDs for diverse biomedical and environmental applications.

Electrochemical Deposition of Copper on Bioactive Porous Titanium Dioxide Layer: Antibacterial and Pro-Osteogenic Activities.

Ti surfaces must exhibit antibacterial activity without cytotoxicity to promote bone reconstruction and prevent infection simultaneously. In this study, we employed a two-step electrochemical treatment process, namely, microarc oxidation (MAO) and cathodic electrochemical deposition (CED), to modify Ti surfaces. During the MAO step, a porous TiO2 (pTiO2) layer with a surface roughness of approximately 2.0 μm was generated on the Ti surface, and in the CED step, Cu was deposited onto the pTiO2 layer on the Ti surface, forming Cu@pTiO2. Cu@pTiO2 exhibited a similar structure, adhesion strength, and crystal phase to pTiO2. Moreover, X-ray photoelectron spectroscopy (XPS) confirmed the presence of Cu in Cu@pTiO2 at an approximate concentration of 1.0 atom %. Cu@pTiO2 demonstrated a sustained release of Cu ions for a minimum of 28 days in a simulated in vivo environment. In vitro experiments revealed that Cu@pTiO2 effectively eradicated approximately 99% of Staphylococcus aureus and Escherichia coli and inhibited biofilm formation, in contrast to the Ti and pTiO2 surfaces. Moreover, Cu@pTiO2 supported the proliferation of osteoblast-like cells at a rate comparable to that observed on the Ti and pTiO2 surfaces. Similar to pTiO2, Cu@pTiO2 promoted the calcification of osteoblast-like cells compared with Ti. In summary, we successfully conferred antibacterial and pro-osteogenic activities to Ti surfaces without inducing cytotoxic effects or structural and mechanical alterations in pTiO2 through the application of MAO and CED processes. Moreover, we found that the pTiO2 layer promoted bacterial growth and biofilm formation more effectively than the Ti surface, highlighting the potential drawbacks of rough and porous surfaces. Our findings provide fundamental insights into the surface design of Ti-based medical devices for bone reconstruction and infection prevention.

Removal of Pb from Contaminated Kaolin by Pulsed Electrochemical Treatment Coupled with a Permeable Reactive Barrier: Tuning Removal Efficiency and Energy Consumption.

Lead contamination in soil has emerged as a significant environmental concern. Recently, pulse electrochemical treatment (PECT) has garnered substantial attention as an effective method for mitigating lead ions in low-permeability soils. However, the impact of varying pulse time gradients, ranging from seconds to hours, under the same pulse duty cycle on lead removal efficiency (LRE) and energy consumption in PECT has not been thoroughly investigated. In this study, a novel, modified PECT method is proposed, which couples PECT with a permeable reaction barrier (PRB) and adds acetic acid to the catholyte. A comprehensive analysis of LRE and energy consumption is conducted by transforming pulse time. The results show that the LREs achieved in these experiments were as follows: PCb-3 s (89.5%), PCb-1 m (91%), PCb-30 m (92.9%), and PCb-6 h (91.9%). Importantly, these experiments resulted in significant reductions in energy consumption, with decreases of 68.5%, 64.9%, 51.8%, and 47.4% compared to constant voltage treatments, respectively. It was observed that LRE improved with an increase in both pulse duration and voltage gradient, albeit with a corresponding rise in energy consumption. The results also revealed that corn straw biochar as a PRB could enhance LRE by 6.1% while adsorbing migrating lead ions. Taken together, the present data highlights the potential of modified PECT technology for remediation of lead-contaminated soil, which provides an optimal approach to achieve high LRE while minimizing energy consumption.

ELECTROCHEMICALLY TREATED LIGNIN IN PHENOLIC RESINS FOR PLYWOOD PANELS

In achieving the European Union's goal of making Europe the first climate-neutral continent by 2050, the scientific community is striving to develop processes and products that are technologically and economically sustainable to replace/substitute fossil-based feedstocks. In this effort, the European project LIBERATE has demonstrated the commercial opportunities of converting low-cost lignin feedstocks into high-value bio sustainable chemicals such as vanillin and mixed phenolic derivatives.Lignin is the largest regenerative source of aromatic organics. In current wood pulping industries, lignin is underutilized and widely considered a side stream primarily exploited for its energy content. A promising approach for the synthesis of biobased fine chemicals is a depolymerisation process for lignin using sodium peroxodicarbonate (PODIC®), an electrochemically produced oxidiser. Within the LIBERATE project, SINTEF has built a pilot scale plant for the electrochemical lignin depolymerisation. The plant provided CHIMAR with the phenol-rich reactor product solution from both kraft and organosolv lignin, which was used as phenol substitutes with up to 50wt% in the formulation of phenol-formaldehyde (PF) resins. These resins have been able to produce successful plywood panels on a laboratory scale. Although their quality is somewhat lower than that of the reference material with traditional PF resin, this work showed that the use of lignin fractions obtained by electrochemical treatment in such an application is possible and promising.

An integrated approach for the assessment of the electrochemical oxidation of diclofenac: By-product identification, microbiological and eco-genotoxicological evaluation

Diclofenac (DCF), a contaminant of emerging concern, is a non-steroidal anti-inflammatory drug widely detected in water bodies, which demonstrated harmful acute and chronic toxicity toward algae, zooplankton and aquatic invertebrates, therefore its removal from impacted water is necessary. DCF is recalcitrant toward traditional treatment technologies, thus, innovative approaches are required. Among them, electrochemical oxidation (EO) has shown promising results. In this research, an innovative multidisciplinary approach is proposed to assess the electrochemical oxidation (EO) of diclofenac from wastewater by integrating the investigations on the removal efficiency and by-product identification with the disinfection capacity and the assessment of the effect on environmental geno-toxicity of by-products generated through the oxidation.The electrochemical treatment successfully degraded DCF by achieving >98 % removal efficiency, operating with NaCl 0.02 M at 50 A m−2. By-product identification analyses showed the formation of five DCF parental compounds generated by decarboxylic and CN cleavage reactions.The disinfection capacity of the EO technique was evaluated by carrying out microbiological tests on pathogens generally found in aquatic environments, including two rod-shaped Gram-negative bacteria (Pseudomonas aeruginosa and Escherichia coli), one rod-shaped Gram-positive bacterium (Bacillus atrophaeus), and one Gram-positive coccus (Enterococcus hirae).Eco-toxicity was evaluated in freshwater organisms (algae, rotifers and crustaceans) belonging to two trophic levels through acute and chronic tests. Genotoxicity tests were carried out by Comet assay, and relative expression levels of catalase, manganese and copper superoxide dismutase genes in crustaceans. Results highlight the effectiveness of EO for the degradation of diclofenac and the inactivation of pathogens; however, the downstream mixture results in being harmful to the aquatic ecosystem.

Research on the descaling characteristics of a new electrochemical water treatment device.

In recent years, chemical water treatment equipment has gained significant attention due to its environmental-friendly features, multifunctionality, and broad applicability. Recognizing the limitations of existing chemical treatment equipment, such as challenges in scale removal and the high water content in scale deposits, we propose a novel drum design for both anode and cathode, enabling simultaneous scale suction and dehydration. We constructed a small experimental platform to validate the equipment's performance based on our model. Notably, under the optimal operating parameters, the hardness removal rate for circulating water falls within the range of 19.6-24.46%. Moreover, the scale accumulation rate per unit area and unit time reaches 13.7 g h-1 m-2. Additionally, the energy consumption per unit weight of the scale remains impressively low at 0.16 kWh g-1. Furthermore, the chemical oxygen demand (COD) concentration decreased from an initial 106.0 mg L-1 to a mere 18.8 mg L-1, resulting in a remarkable total removal rate of 82.26%. In conclusion, our innovative electrochemical water treatment equipment demonstrates exceptional performance in scale removal, organic matter degradation, and water resource conservation, offering valuable insights for future research and development in chemical treatment equipment and electrochemical theory.

Electrochemical treatment of municipal reverse osmosis concentrates by a TiO2-BNTs/SnO2-Sb reactive electrochemical membrane

With the wide application of reverse osmosis technology in municipal wastewater treatment, the abundance of generated reverse osmosis concentrates (ROC) has become a significant challenge for water ecosystems. In this work, a fabricated TiO2-BNTs/SnO2-Sb reactive electrochemical membrane (REM) was used to dispose of municipal ROC wastewater. The effects of the TiO2 nanotube array (TiO2-BNTs) interlayer, current density, initial pH and flow rate on the COD removal of ROC were investigated. In addition, the 3D-EEM fluorescence spectra showed that humic acid-like substances and soluble microbial byproduct-like substances could be removed effectively. GC-MS analysis indicated that most organics, including aldehydes, phenols, ethers, nitriles, ketones, silanes and alcohols, were eliminated after treatment. The REM also exhibited prominent membrane anti-fouling performance in high-salinity wastewater. After 20 cycles, the transmembrane pressure (TMP) was only slightly changed (within 3 kPa) compared to that of the first cycle. Two key parameters, i.e., service lifetime and energy consumption, were investigated in ROC treatment. The service lifetime reached 31350 h (3.5 years, 20 mA cm−2) in 0.5 M NaCl solution and 40390 h (20 mA cm−2, 4.6 years) in actual wastewater, which is highly competitive with previously reported electrodes. Energy consumption reached 10.5 kWh·kg COD−1 in actual ROC wastewater, which is more acceptable compared with current reported electrochemical technologies and exhibits great application prospects for TiO2-BNTs/SnO2-Sb REMs.

Effects of electrochemical treatment and Epigallocatechin-3-gallate on emulsification, rheological and oxidation stability of soybean oil body

In this study, the soybean oil body (SOB) was placed in the cathode chamber of an electrochemical reactor, H+ enters the cathode chamber through the proton exchange membrane to undergo reduction reaction. The complex of SOB and Epigallocatechin-3-gallate (EGCG) was prepared on the basis of electrochemical treatment (ESOB-EGCG). The effects of two treatment on the structure and thermal properties of SOB protein were analyzed, which provided a basis for the study on the emulsification, rheological and oxidation stability of SOB emulsion. The results showed that the EAI of ESOB-EGCG was 108% higher than that of SOB, and the emulsion showed greater viscosity and the largest linear viscoelastic region. Through the determination of oxidation stability and fitting of oxidation kinetic model, it was found that ESOB-EGCG sample showed the best oxidation stability, which provided support for fitting and predicting the oxidation stability of SOB.