Use of nano zero-valent iron to reduce inorganic species electrogenerated during anodic oxidation on boron doped diamond anodes

In this paper, the solution coming from an anodic oxidation on boron doped diamond of chloride-containing solution is treated with addition of nano zero-valent iron (nZVI) to reduce the amount of chlorinated byproducts into chloride ions. The electrolyzed solutions have been obtained under galvanostatic conditions in an undivided reactor. The evolution and depletion of all the chlorinated species have been monitored by spectrophotometry and ion chromatography. The nanoscale iron particles have been synthesized in our laboratory by a fast and facile method through reaction of FeSO4 and NaBH4 solutions without addition of dispersants. The effect on the conversion yield of several operative parameters has been investigated and discussed. The preliminary results indicate that a nZVI postreatment can be considered a viable technology for the treatment of solutions containing active chlorine and chlorate. However, the reduction of perchlorate, either in mixed solutions or alone, requires too drastic conditions to be completed

Investigating the effects of continuous electrochlorination on bacteria, bacteriophage and DNA.

Disinfection of drinking water is a vital step to generate pathogen-free water. Continuous electrochlorination (CEC) is emerging as an alternative to the traditional use of chlorine as a disinfectant for water treatment. CEC is an electrochemical method of converting chloride ions into chlorine. This study investigated the disinfection efficiency of a pilot and laboratory CEC unit developed by Water Corporation. CEC has proved to be an efficient technology for disinfecting groundwaters in WA

Reactor design for electrochemical oxidation of the persistent organic pollutant 1,4-dioxane in groundwater

2018 Spring.Includes bibliographical references.The common industrial solvent stabilizer and wetting agent 1,4-dioxane (DX) is one of the most widely occurring organic groundwater contaminants in the United States today. It is a probable human carcinogen, highly mobile in groundwater, and resistant to anaerobic biodegradation. The ineffectiveness of conventional treatment approaches such as stripping and sorption to activated carbon results in a critical need of advanced technologies for the treatment of DX in groundwater. Previous studies have shown that electrochemical oxidation is able to fully mineralize 1,4-dioxane, but testing has thus far been limited to proof-of-principle bench-scale experiments. Consequently, this study addresses the design of a configurable mobile pilot-scale reactor that can be used to test electrochemical degradation performance under site-specific conditions and with different dimensionally stable electrode materials. The goal of this reactor design is to accommodate straightforward scale-up for field applications, and low cost of production so that ultimately multiple modular units can be deployed to operate in series or in parallel. Assessment of critical design parameters in a bench-scale reactor showed that DX degradation rates almost doubled when no inter-electrode solid media were used. No significant differences were observed between operating the reactor in continuous versus batch mode. An additional 57% degradation rate improvement was achieved when the batch reactor was operated with 30-minute polarity reversals as compared with constant polarity. Bench-scale reactor and initial pilot reactor tests with Ti/IrO2-Ta2O5 electrodes were run using a synthetic groundwater solution containing DX in NaCl electrolyte, revealing substantial effects of scale, while DX degradation kinetics were similar. Groundwater from a contaminated industrial site was then treated in the pilot reactor with an apparent anode surface area per order of magnitude DX removal (ASAAO) of 305 h*m2/m3 at an electric energy consumption per order of magnitude DX removal (EEO) of 152 kWh/m3, with relatively minor production of undesirable by-products. The contaminated site groundwater was also treated in a commercial bench-scale reactor with a Magnéli-phase titanium oxide anode, resulting in an ASAAO of 28 h*m2/m3 at an EEO of 176 kWh/m3, but with a high yield of carbon tetrachloride (CCl4) and chlorate (ClO3-), and minor formation of perchlorate (ClO4-). In comparison of the surface-area normalized rates of removal, the commercial reactor was faster than the pilot reactor, but it consumed more energy per order reduction and generated more undesirable reaction by-products, commonly referred to as disinfection by-products (DBPs). Future testing at contaminated field sites will reveal the efficacy of our newly designed reactor, and thus electrochemical treatment, for the remediation of groundwater contaminated with DX and other persistent organic pollutants

Chlorate and Other Oxychlorine Contaminants Within the Dairy Supply Chain

The presence of chlorate in milk and dairy products can arise from the use of chlorinated water and chlorinated detergents for cleaning and sanitation of process equipment at both farm and food processor level. Chlorate and other oxychlorine species have been associated with inhibition of iodine uptake in humans and the formation of methemoglobin, with infants and young children being a high‐risk demographic. This comprehensive review of chlorate and chlorine derivatives in dairy, highlights areas of concern relative to the origin and/or introduction of chlorate within the dairy supply chain. This review also discusses the associated health concerns, regulations, and chemical behavior of chlorate and chlorine‐derived by‐products, and provides a summary of mechanisms for their detection and removal

Initial Study and Verification of a Distributed Fiber Optic Corrosion Monitoring System for Transportation Structures

For this study, a novel optical fiber sensing system was developed and tested for the monitoring of corrosion in transportation systems. The optical fiber sensing system consists of a reference long period fiber gratings (LPFG) sensor for corrosive environmental monitoring and a LPFG sensor coated with a thin film of nano iron and silica particles for steel corrosion monitoring. The environmental effects (such as pH and temperature) are compensated by the use of the reference LPFG sensor. The sensor design, simulation, and experimental validation were performed in this study to investigate the feasibility of the proposed sensing system for corrosion and environment monitoring. The detailed investigations of the proposed sensing system showed that within the detection limitation of the thin coated layer, the proposed sensor could monitor both the initial and stable corrosion rate consistently. Compared to the traditional electrochemical method, the proposed optical fiber sensing system has a converter coefficient of 1 nm/day=3.746×10-3 A/cm2. Therefore, the proposed nano iron/silica particles dispersed polyurethane coated optical fiber sensor can monitor the critical corrosion information of the host members in real time and remotely. With multiple LPFGs in a single fiber, it is possible to provide a costeffective, distributed monitoring solution for corrosion monitoring of large scale transportation structures

Determination of chlorine species by capillary electrophoresis: mass spectrometry

L

A Nitrite Biosensor Based on Co-immobilization of Nitrite Reductase and Viologen-modified Chitosan on a Glassy Carbon Electrode

An electrochemical nitrite biosensor based on co-immobilization of copper- containing nitrite reductase (Cu-NiR, from Rhodopseudomonas sphaeroides forma sp. denitrificans) and viologen-modified chitosan (CHIT-V) on a glassy carbon electrode (GCE) is presented. Electron transfer (ET) between a conventional GCE and immobilized Cu-NiR was mediated by the co-immobilized CHIT-V. Redox-active viologen was covalently linked to a chitosan backbone, and the thus produced CHIT-V was co-immobilized with Cu-NiR on the GCE surface by drop-coating of hydrophilic polyurethane (HPU). The electrode responded to nitrite with a limit of detection (LOD) of 40 nM (S/N = 3). The sensitivity, linear response range, and response time (t90%) were 14.9 nA/μM, 0.04−11 μM (r2 = 0.999) and 15 s, respectively. The corresponding Lineweaver-Burk plot showed that the apparent Michaelis-Menten constant (KMapp) was 65 μM. Storage stability of the biosensor (retaining 80% of initial activity) was 65 days under ambient air and room temperature storage conditions. Reproducibility of the sensor showed a relative standard deviation (RSD) of 2.8% (n = 5) for detection of 1 μM of nitrite. An interference study showed that anions commonlyfound in water samples such as chlorate, chloride, sulfate and sulfite did not interfere with the nitrite detection. However, nitrate interfered with a relative sensitivity of 64% and this interference effect was due to the intrinsic character of the NiR employed in this study