Steel Electrodes Research Articles

Improvement in Galvanic Corrosion Resistance between AA5083 and Pure Fe or Stainless Steels in Diluted Synthetic Seawater Due to Anodizing

Because of worldwide emission gas control, the weight reduction for automobiles has been widely required. Multi-material structures for automobiles, in which several materials like steels and aluminum alloys are utilized, are effective methods as techniques to reduce the weight; however, the galvanic corrosion becomes a serious problem for the joints between steels and aluminum alloys. In our previous research [1], galvanic corrosion damages on pure aluminum coupled to pure iron or stainless steel were prevented by anodizing because the anodic oxide film on pure aluminum becomes thicker with increasing anodizing time and voltage. For aluminum alloys, intermetallic particles on aluminum alloys become the initiation sites of localized corrosion; therefore, anodizing behavior on intermetallic particles should be important for preventing the galvanic corrosion damage on aluminum alloys. In this research, anodizing conditions were determined to prevent the localized corrosion generation on AA5083 when pure iron or stainless steels were coupled to AA5083. Pure iron, type 304 stainless steel, type 430 stainless steel, and AA5083 (Al-Mg alloy) were prepared as specimens in this research. Diluted synthetic seawater (200 mg/L Cl-, pH 8.2) was used as the electrolyte for electrochemical measurements. The electrode area was ca. 10 mm2. Ag/AgCl (3.33 M KCl) was used as the reference electrode. Galvanic currents and electrode potentials of aluminum alloy electrode were measured via a zero resistance ammeter. The distance between steel and aluminum alloy electrodes was kept at 10 mm. Additionally, anodizing was treated to AA5083 in various anodizing voltage and time conditions. The galvanic currents and electrode potentials of AA5083 coupled to pure iron were measured. The galvanic currents were anodic currents during the measurements, and the small oscillations of galvanic currents and electrode potentials were generated. After the measurements, many pits and filiform corrosion were observed on AA5083. The localized corrosion was induced by ennoblement of the electrode potentials of AA5083.[1] Takumi Kosaba, Izumi Muto, Yu Sugawara: Effect of anodizing on galvanic corrosion resistance of Al coupled to Fe or type 430 stainless steel in diluted synthetic seawater, Corros. Sci., 179 (2021), 109145.

Characterizing the Impact of the Oxygen Reduction Reaction Mechanism and Current Distribution on Mineral Deposit Structure and Composition

In marine environments, cathodic protection is applied to metallic structures to prevent corrosion through polarization. The cathodic current causes secondary mineral deposition reactions, whose makeup, phase, and existence are dependent on the pH at the interface. These deposits can cause a significant increase in the interfacial impedance through electrolytic exclusion and obstructions to diffusion. Two factors contributing to the pH at a surface are current distributions across a surface and the reaction mechanism mediating the current. This work looks at the influence of these two factors on the make-up, phase and surface impedance impacts of mineral deposits on electrode surfaces. The role of Oxygen Reduction Reaction (ORR) mechanism and current distribution on the formation of Ca and Mg deposits on platinum and 316L stainless steel were assessed using a combination of rotating disc electrode (RDE), electrochemical impedance spectroscopy (EIS), and surface analysis techniques.In order to verify the material and potential dependent ORR mechanisms on platinum, glassy carbon, and 316L stainless steel, a series of RDE experiments were conducted. The platinum electrode and glassy carbon electrodes were shown to have excellent agreement with the predicted Levich behavior for a 4-electron ORR mechanism and a 2-electron ORR mechanism respectively, for all of the potentials in the mass transport limiting current range for ORR. However, the 316L stainless steels samples exhibited a deviation in the predicted Levich response at lower cathodic overpotentials in the ORR limiting current region. This behavior has been hypothesized to be caused by a reduction in the iron oxide layer present on the stainless-steel surface, which in turn results in an increase in ORR efficiency at more cathodic overpotentials. This transition in ORR efficiency may result in a change in the interfacial pH gradient, and impact the resultant mineral deposit structure and composition. In this work, four different ORR mechanism conditions were evaluated in terms of mineral deposit formation potential: polished platinum electrodes, polished glassy carbon electrodes, polished 316L stainless steel electrodes, and pre-reduced 316L stainless steel electrodes.Current distribution was evaluated in a fabricated, macro scale scanning probe system. These experiments assessed Pt and 316L as a 7 cm diameter disk working electrode, surrounded by a platinized ring counter electrode under quiescent conditions. Current distribution was observed via electric field measurement and surface potential mapping. The electrodes were polarized in ASTM D1141 artificial seawater, and the growth of the deposit was monitored in situ using EIS. The structure of the deposits on each material was evaluated by confocal profilometry and scanning electron microscopy with energy dispersive x-ray spectroscopy to determine structure and chemical composition. Mineral deposits were evaluated spatially and correlated to RDE work via an equipotential model. The work presented here provides insight into the contribution of ORR mechanism and current distribution across several size scales, on mineral deposit formation on materials with both ideal and hybrid ORR activity.

Stimulation of the dorsal root ganglion using an Injectrode®

Objective. The goal of this work was to compare afferent fiber recruitment by dorsal root ganglion (DRG) stimulation using an injectable polymer electrode (Injectrode®) and a more traditional cylindrical metal electrode. Approach. We exposed the L6 and L7 DRG in four cats via a partial laminectomy or burr hole. We stimulated the DRG using an Injectrode or a stainless steel (SS) electrode using biphasic pulses at three different pulse widths (80, 150, 300 μs) and pulse amplitudes spanning the range used for clinical DRG stimulation. We recorded antidromic evoked compound action potentials (ECAPs) in the sciatic, tibial, and common peroneal nerves using nerve cuffs. We calculated the conduction velocity of the ECAPs and determined the charge-thresholds and recruitment rates for ECAPs from Aα, Aβ, and Aδ fibers. We also performed electrochemical impedance spectroscopy measurements for both electrode types. Main results. The ECAP thresholds for the Injectrode did not differ from the SS electrode across all primary afferents (Aα, Aβ, Aδ) and pulse widths; charge-thresholds increased with wider pulse widths. Thresholds for generating ECAPs from Aβ fibers were 100.0 ± 32.3 nC using the SS electrode, and 90.9 ± 42.9 nC using the Injectrode. The ECAP thresholds from the Injectrode were consistent over several hours of stimulation. The rate of recruitment was similar between the Injectrodes and SS electrode and decreased with wider pulse widths. Significance. The Injectrode can effectively excite primary afferents when used for DRG stimulation within the range of parameters used for clinical DRG stimulation. The Injectrode can be implanted through minimally invasive techniques while achieving similar neural activation to conventional electrodes, making it an excellent candidate for future DRG stimulation and neuroprosthetic applications.

Characteristics and corrosion protection of polypyrrole doped with salicylate anions on CT3 steel passivated by molydate

In recent years, the conducting polymers have attracted much attention in research and development because of their applications in medical and civil engineering. Here, the salicylate doped polypyrrole films were prepared on the carbon steel surface and their corrosion protection in 3 % NaCl solution were studied. Polypyrrole (Ppy) film was electrochemically synthesised with constant current techniques in a sodium salicylate solution (0.05M, 0.1M, 0.15M) and 0.1M pyrrole monomer on mild CT3 steel electrode passivated by molybdate. The morphological, structural, composition and thermal properties of salicylate doped Ppy films were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA) techniques. The anti-corrosion ability of these films was assessed by electrochemical measurements in 3 % NaCl solution. The obtained results suggested that salicylate anions contributed in corrosion protection ability of Ppy films for mild steel electrode. The concentration of sodium salicylate of 0.1M and pyrrole of 0.1M is most suitable for preparation of good protection coating. The self-healing mechanism has been also mentioned for salicylate doped Ppy films on CT3 steel substrate.

Electrochemical Neutralization of Acidic Industrial Effluents

An electrochemical method for neutralizing "acidic" industrial effluents is presented. The dependences of the electrical conductivity of industrial water on the neutralization time on platinum and steel electrodes are compared.

Colossal thermo-hydro-electrochemical voltage generation for self-sustainable operation of electronics

Thermoelectrics are suited to converting dissipated heat into electricity for operating electronics, but the small voltage (~0.1 mV K−1) from the Seebeck effect has been one of the major hurdles in practical implementation. Here an approach with thermo-hydro-electrochemical effects can generate a large thermal-to-electrical energy conversion factor (TtoE factor), −87 mV K−1 with low-cost carbon steel electrodes and a solid-state polyelectrolyte made of polyaniline and polystyrene sulfonate (PANI:PSS). We discovered that the thermo-diffusion of water in PANI:PSS under a temperature gradient induced less (or more) water on the hotter (or colder) side, raising (or lowering) the corrosion overpotential in the hotter (or colder) side and thereby generating output power between the electrodes. Our findings are expected to facilitate subsequent research for further increasing the TtoE factor and utilizing dissipated thermal energy.

Induced Dipoles and Possible Modulation of Wireless Effects in Implanted Electrodes. Effects of Implanting Insulated Electrodes on an Animal Test to Screen Antidepressant Activity.

There is evidence that Deep Brain Stimulation (DBS) produces health benefits in patients even before initiating stimulation. Furthermore, DBS electrode insertion in rat infralimbic cortex (ILC) provokes antidepressant-like effects before stimulation, due to local inflammation and astrogliosis. Consequently, a significant effect of implanting electrodes is suspected. External fields, similar in magnitude to the brain’s endogenous fields, induce electric dipoles in conducting materials, in turn influencing neural cell growth through wireless effects. To elucidate if such dipoles influence depressive-like behavior, without external stimulation, the comparative effect of conducting and insulated electrodes along with the glial response is studied in unstressed rats. Naïve and implanted rats with electrically insulated or uninsulated steel electrodes were evaluated in the modified forced swimming test and expression of ILC-glial markers was assessed. An antidepressant-like effect was observed with conducting but not with insulated electrodes. Gliosis was detected in both groups, but astroglial reactivity was larger near uninsulated electrodes. Thus, induced dipoles and antidepressant-like effects were only observed with conducting implants. Such correlation suggests that dipoles induced in electrodes by endogenous fields in turn induce neuron stimulation in a feedback loop between electrodes and neural system. Further research of the effects of unwired conducting implants could open new approaches to regulating neuronal function, and possibly treat neurological disorders.

Effects of simulated in-situ electrokinetic remediation on physicochemical properties and phosphorus migration of sediments

The effect of simulated in-situ electrokinetic remediation (EKR) on phosphorus release from contaminated sediments was investigated. The effects of different anode materials (iron, aluminum, graphite and stainless steel) on the physicochemical properties and phosphorus migration were compared. The results showed that aluminum anode had the best inhibition effect on phosphorus release from sediments, and the highest inhibition rate of phosphorus release was 78.20% compared with non EKR, but the sustainability was poor, and the performance of iron anode is generally stable. The phosphorus in the sediments generally shows the migration trend from cathode to anode. After EKR, the Oxidation-Reduction Potential (ORP) of the sediment decreased with the increase of normalized distance from anode. The anaerobic environment of the sediment on iron anode was the most serious, and the lowest was -616mV. The ORP of the sediment from the anode area to the middle area of other electrodes was effectively improved. The pH of the sediment increases gradually from anode to cathode, and is characterized by acidification in the anode area and alkalization in the cathode area. Iron and stainless steel electrodes have more acidic areas, showing better electrolysis efficiency.

The electrodeposition of Ni-Cu and Ni-Cu-P from aspartate-based baths

The electrodeposition of Ni-Cu and Ni-Cu-P was performed over steel electrodes using baths containing aspartate as a complexing agent for the metallic cations. Through the rotating disk electrode technique and the measurement of the deposition potentials, it was found that the electrodeposition is controlled by activation at current densities (jdep) equal or lower than 10 mA cm−2 and suffers limitations on diffusion for jdep>10 mA cm−2. The hydrogen evolution reaction during the electrodeposition was more intense over Ni-Cu-P films leading to a lower efficiency compared to the Ni-Cu films. The composition of the amount of Cu in the Ni-Cu films varied from 13.7% to 21.5%, while the amount of Cu in the Ni-Cu-P films varied from 24.4% to 43.1%. The P incorporation was low, varying from 1.2% to 2.8%. For the Ni-Cu films, globular, dendritic, and smooth films were obtained depending on the deposition control and the efficiency. The Ni-Cu-P presented dendritic and smooth morphology depending on the efficiency.

Electrochemical Impedance Imaging on Conductive Surfaces

Electrochemical impedance spectroscopy (EIS) is a powerful tool to measure and quantify the system impedance. However, EIS only provides an average result from the entire electrode surface. Here, we demonstrated a reflection impedance microscope (RIM) that allows us to image and quantify the localized impedance on conductive surfaces. The RIM is based on the sensitive dependence between the materials' optical properties, such as permittivity, and their local surface charge densities. The localized charge density variations introduced by the impedance measurements will lead to optical reflectivity changes on electrode surfaces. Our experiments demonstrated that reflectivity modulations are linearly proportional to the surface charge density on the electrode and the measurements show good agreement with the simple free electron gas model. The localized impedance distribution was successfully extracted from the reflectivity measurements together with the Randles equivalent circuit model. In addition, RIM is used to quantify the impedance on different conductive surfaces, such as indium tin oxide, gold film, and stainless steel electrodes. A polydimethylsiloxane-patterned electrode surface was used to demonstrate the impedance imaging capability of RIM. In the end, a single-cell impedance imaging was obtained by RIM.

Removal of Acid Red 131 by Peroxi-Coagulation Using Stainless Steel and Aluminum Electrodes: a Comparative Study

Removal of Acid Red 131 by Peroxi-Coagulation Using Stainless Steel and Aluminum Electrodes: a Comparative Study

Improving the Treatment Efficiency and Lowering the Operating Costs of Electrochemical Advanced Oxidation Processes

Electrochemical advanced oxidation processes (EAOP®) are promising technologies for the decentralized treatment of water and will be important elements in achieving a circular economy. To overcome the drawback of the high operational expenses of EAOP® systems, two novel reactors based on a next-generation boron-doped diamond (BDD) anode and a stainless steel cathode or a hydrogen-peroxide-generating gas diffusion electrode (GDE) are presented. This reactor design ensures the long-term stability of BDD anodes. The application potential of the novel reactors is evaluated with artificial wastewater containing phenol (COD of 2000 mg L−1); the reactors are compared to each other and to ozone and peroxone systems. The investigations show that the BDD anode can be optimized for a service life of up to 18 years, reducing the costs for EAOP® significantly. The process comparison shows a degradation efficiency for the BDD–GDE system of up to 135% in comparison to the BDD–stainless steel electrode combination, showing only 75%, 14%, and 8% of the energy consumption of the BDD–stainless steel, ozonation, and peroxonation systems, respectively. Treatment efficiencies of nearly 100% are achieved with both novel electrolysis reactors. Due to the current density adaptation and the GDE integration, which result in energy savings as well as the improvements that significantly extend the lifetime of the BDD electrode, less resources and raw materials are consumed for the power generation and electrode manufacturing processes.

An expeditious and efficient method for the oxidation of benzyl alcohols by homogeneous electrolysis

A greener and inexpensive electrochemical method has been developed for the oxidation of benzyl alcohols by homogeneous electrolysis. The electrochemical reaction was carried out in an undivided cell equipped with carbon and stainless steel electrodes at room temperature. The homogeneous solution made up of acetonitrile/water containing substrate and ammonium bromide with a catalytic amount of H2SO4 as supporting electrolyte. The reaction condition was optimized with various electrochemical experimental parameters and evaluated with various substituted benzyl alcohols to result in excellent yield of aldehydes (>83%).

Development of Ag and Ag alloys-precipitated Ag2O-TeO2 glass and Ag2O-TeO2 glass/stainless steel reference electrodes for pH sensors

An Ag/AgCl reference electrode that is built into commercially available pH electrodes leaks its internal KCl solution via a liquid junction. This leakage is disadvantageous because the test solution is contaminated by a trace amount of the KCl solution. The applicability of Ag2O-TeO2 glasses to reference electrodes for pH sensors was investigated in this study. The effects of the Ag2O content and heat treatment on the pH sensitivity of these glasses and the pH sensitivity of the Ag2O-TeO2 glass/stainless steel electrodes were examined. The pH sensitivity of Ag2O-TeO2 glasses increased as the Ag2O content increased, but it was less than 40 % and was the lowest among the glasses that have been investigated to date. The heat-treated 25Ag2O･75TeO2 glass and 25Ag2O･75TeO2 glass/stainless steel electrodes precipitated cubic Ag and hexagonal Ag and showed relatively low pH sensitivities of 26 % and 5 %, respectively. Thus, the hexagonal Ag and Ag alloys-precipitated samples were considered candidate reference electrodes for pH sensors.

Effect of electrode shape and deposition technique on electrochemical treatment of ampicillin in water

The effect of stainless steel (SS) electrode shape on electrochemical treatment of pharmaceutical pollutant has been studied. Anodes consisting of SS plate and SS grid coated with lead dioxide (PbO 2 ) were prepared by different deposition techniques: electrodeposition (ED), sol gel method (SG) using spin-coating (SC) and dip-coating (DC) depending on the electrode shape. The influence of the substrate shape and the deposition method on the oxidizing performance of the elaborated electrode was studied. The surface morphology and the composition of the PbO 2 layer were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). XRD analysis revealed the presence of β -PbO 2 form with both deposition techniques in addition to the chromium (Cr) phase attributed to the SS substrate. Electrochemical Impedance Spectroscopy (EIS) measurements were performed for assessing the electrochemical behavior of the SS/PbO 2 anodes. EIS results demonstrated a smaller charge transfer resistance with PbO 2 ED coating compared to PbO 2 SG . The degradation of ampicillin as pharmaceutical pollutant was evaluated with high performance liquid chromatography and chemical oxygen demand (COD) for overall mineralization of organic matter and to evaluate the related average current efficiency (ACE) and energy consumption (EC). This study demonstrated that SS grid /PbO 2 ED is the most efficient electrode for electrochemical treatment with 100% of ampicillin removal after 120 min of treatment. • Ampicillin degradation by anodic oxidation is studied. • Plate and grid substrates are used for the fabrication of PbO 2 anode. • PbO 2 coating is deposited by electrodeposition and sol gel techniques. • SS grid PbO 2 ED is the most efficient anode for ampicillin removal.

Advancement of ozone zero phenomenon by surface deterioration of stainless—steel electrode

It is well known that a fine powder is deposited on the surface of coaxial cylinder electrodes made from stainless steel and borosilicate glass in ozone generators. We inspected the fine powder and the stainless steel by x-ray diffraction and Auger electron spectroscopy to clarify the relationship between the gradual decrease in ozone concentration, i.e., ozone zero phenomena (OZP) produced in the ozone generator, and the deterioration of stainless steel. The results of x-ray diffraction for both specimens suggest that several oxides with iron, chromium and nickel are formed from the stainless steel exposed to an ozone–oxygen mixture and the discharge. In particular, FeO detected by x-ray diffraction analysis means that the temperature of the surface of stainless steel and the powder reaches at least 843 K owing to the generation of heat by discharge and oxidation of the fine powder and electrode surface despite the inside of electrodes being refrigerated with circulating water. This temperature is much higher than the 453 K estimated in our previous work as a threshold temperature of the thermal decomposition of ozone by model experiments using a simulated ozone generator during the OZP. On the other hand, Auger electron spectroscopy is carried out in combination with the repeated tracing of the OZP, and we investigate whether oxygen atoms penetrate in the depth direction of the stainless steel. During this process, we observed serious OZP, meaning the ozone concentration at the outlet of the ozone generator is almost zero for 40–50 h continuously following the gradual decrease in ozone concentration. The penetration of oxygen atoms into the stainless-steel bulk is considered as the start of the collapse of the original passivation film covering on the surface of stainless steel. After the process, i.e., the cessation of the OZP, the formation of a new thin layer instead of the passivation film is observed with the coexistence of a strong oxidizer, i.e., ozone and atomic oxygen and the heat produced by discharge in the ozone generator. However, the recovered ozone concentration is realized up to half of the peak value in the measurement. This process corresponds to the recovery of the ozone concentration after the OZP. Hence, we concluded that the OZP is advanced by the thermal decomposition of ozone accompanied by the deterioration of the stainless-steel surface by ozone oxidation.

Treatment of biologically treated distillery spent wash employing electrocoagulation and reverse-osmosis treatment train

ABSTRACT In the present study, electro-coagulation (EC) with stainless steel (SS) electrodes has been used as a pretreatment process before the reverse osmosis (RO) for the biologically treated distillery spent wash. The optimized operating parameters (pH, time, current, and electrode distance) for the EC process were obtained from the previous study. EC treated wastewater was further used as a feed for the RO system. RO membrane system operating parameters (pH, temperature, and trans-membrane pressure) were optimized by employing response surface methodology. Optimized conditions for the RO process were found to be: pH (pHo): 6.12; temperature (T): 20°C and trans-membrane pressure (TMP): 45.7 bar. The combined (EC-RO) process showed 98%, 99.2%, and 98.5% of COD, color, and TDS removal, respectively, with permeate flux of 40.5 L/m2/h (EC-RO). Experimental results indicated that EC followed by RO could be used as an additional step for biologically treated spent wash treatment to improve the treated effluent quality and membrane life. Results also revealed that the techno-economic performance of combined (EC-RO) treatment in terms of total annual water production is more efficient and economical than RO alone.

CATALYTIC PROPERTIES OF Ni-V COATING IN THE PROCESS OF HYDROGEN RELEASE

Solar and hydrogen energy play an important role in providing a variety of industrial facilities with electricity and heat. One of the priorities of modern industry is to increase the production of environmentally friendly energy source – electrochemical synthesis of hydrogen. Modern methods of electrolysis of water do not meet the need for its use, due to the high cost of electrosynthesis of water-alkaline electrolysis, which depends on the material and energy consumption of electrolysis.
 The useful energy consumption for the production of energy – hydrogen at the cathode and "unnecessary" costs - for the release of oxygen at the anode, depend on the overvoltage of the respective reactions. Therefore, the most important problem of hydrogen energy is the synthesis of electrode materials with low overvoltage of O2 and H2. Electrode materials with low overvoltage will reduce the specific consumption of electricity in obtaining hydrogen by "classical" electrolysis.
 The prospects of reducing the cathodic and anodic overvoltage, which is a significant part of the voltage at the terminals of the cell, for the development of highly efficient and competitive technologies for hydrogen production by low-temperature electrolysis of an alkaline solution have been theoretically substantiated and experimentally confirmed. To reduce the overvoltage of the cathodic hydrogen evolution, it is proposed to modify the surface of the cathodes. The application of a small amount of electrolytic alloys of metals of the iron family with molybdenum and tungsten on nickel, cobalt, titanium and steel electrodes significantly (by 40–50 %) reduces the overvoltage of cathodic release of hydrogen from alkali solution.
 The use of steel electrodes, the surface of which is modified with vanadium and ni-ckel, reduces the voltage drop on the cell during the synthesis of H2 and O2 by 0.2–0.3 V, which creates conditions for reducing energy costs and energy savings.

The effects of different electrode materials on seed germination of Solanum nigrum L. and its Cd accumulation in soil

The effects of different electrode on Solanum nigrum L. seed germination were determined. The result showed that germination percentage (GP) of seeds in treatment T2 (titanium electrode) was 26.6% higher than in control (CK, without electric field). High potassium and calcium concentrations were beneficial for seed enzymatic activity in treatment T2, which could partly explain the increase in GP. Cd accumulation (μg/pot) in S. nigrum treated with any electric field was significantly higher (p<0.05) than in CK without electric field. Specifically, Cd accumulation under the treatment T3 (stainless steel electrode) was the highest both in roots and shoots; this accumulation in shoots and roots were 74.7 % and 67.4 % higher for stainless steel than in CK. This increase must have been associated with a higher Cd concentration in plants and did not exert a significant effect on the biomass. In particular, Cd concentrations in roots and shoots under stainless steel treatment were both significantly higher than in CK (p<0.05), which had to be related to the higher available Cd concentration in the soil in the middle region. Furthermore, it could be attributed to altered soil pH and other soil properties. Moreover, none of the biomasses were significantly affected (p<0.05) by different electrode materials compared to CK.

Turnover of lake sediments treated with sediment microbial fuel cells: a long-term study in a eutrophic lake

Sediment microbial fuel cells (SMFCs) have previously been successfully used to reduce phosphate release from the sediments of eutrophic lakes. In this study, we investigate the risk that SMFCs stimulate sediment decomposition with the unwanted side effect being the release of legacy pollutants stored in sediments. Electrode pairs (16 m2 each) were installed in a eutrophic lake in Denmark and the electricity production was monitored over more than a year at three electrode fields. Equations were derived that allow calculation of the substrate turnover by the SMFCs from the working potential, the open circuit potential, and the external resistance of the SMFCs. The resulting turnover data suggest that the decomposition of the sediment is only slightly expedited by the SMFCs, and that the decomposition process is not significantly stimulated by the type of SMFCs installed in the lake. The measured maximum power density with stainless steel electrodes in the lake sediment was 0.9 mW/m2, which was sufficient to reduce P outflux from sediment. At this power density, the decomposition half-life of the lake sediment (top 5 cm) is calculated to be 277 years, which is only about 10% of natural lake sediment decomposition half-lives. Higher power densities are not necessary for P fixation but inadvertently increase the risk that legacy pollutants buried in the sediment are released.