scholarly journals Elimination of Oxygen Interference in the Electrochemical Detection of Monochloramine, Using In-Situ pH Control at Interdigitated Electrodes

2020 ◽  
Author(s):  
Ian Seymour ◽  
Benjamin O'sullivan ◽  
Pierre Lovera ◽  
Alan O'Riordan ◽  
James Rohan
Keyword(s):  
Control Method ◽  
Primary Source ◽  
Ph Control ◽  
Water Systems ◽  
Potential Sweep ◽  
Sensor Development ◽  
Concentration Potential ◽  
Copper Phosphate ◽  
High Alkalinity

Disinfection by chloramination of water systems is an alternative to chlorination that is frequently used in North America. In such a case, monochloramine is used as the primary source of chlorine for disinfection. Regular monitoring of the residual concentrations of this species is crucial to ensure adequate disinfection. An amperometric sensor for monochloramine would provide fast, reagent free analysis, however the presence of dissolved oxygen in water complicates sensor development. In this work, we have explored the use of in-situ pH control as a method of eliminating oxygen as an interferent by conversion of monochloramine to dichloramine. The electrochemical reduction of dichloramine occurs outside the oxygen reduction window and is therefore not affected by oxygen concentration. Potential sweep methods were used to investigate the conversion of monochloramine to dichloramine at pH 3. The pH control method was used to calibrate monochloramine concentrations between 1 and 10 ppm, with a detection limit of 0.03 ppm. Tests were carried out in high alkalinity samples, wherein it was found that the sensitivity of this method effectively remained unchanged. Monochloramine was also quantified in the presence of common interferents (copper, phosphate and iron) which had no significant impact on the analysis

scholarly journals Elimination of Oxygen Interference in the Electrochemical Detection of Monochloramine, Using In-Situ pH Control at Interdigitated Electrodes

2020 ◽  
Author(s):  
Ian Seymour ◽  
Benjamin O'sullivan ◽  
Pierre Lovera ◽  
Alan O'Riordan ◽  
James Rohan
Keyword(s):  
Control Method ◽  
Primary Source ◽  
Ph Control ◽  
Water Systems ◽  
Potential Sweep ◽  
Sensor Development ◽  
Concentration Potential ◽  
Copper Phosphate ◽  
High Alkalinity

Disinfection by chloramination of water systems is an alternative to chlorination that is frequently used in North America. In such a case, monochloramine is used as the primary source of chlorine for disinfection. Regular monitoring of the residual concentrations of this species is crucial to ensure adequate disinfection. An amperometric sensor for monochloramine would provide fast, reagent free analysis, however the presence of dissolved oxygen in water complicates sensor development. In this work, we have explored the use of in-situ pH control as a method of eliminating oxygen as an interferent by conversion of monochloramine to dichloramine. The electrochemical reduction of dichloramine occurs outside the oxygen reduction window and is therefore not affected by oxygen concentration. Potential sweep methods were used to investigate the conversion of monochloramine to dichloramine at pH 3. The pH control method was used to calibrate monochloramine concentrations between 1 and 10 ppm, with a detection limit of 0.03 ppm. Tests were carried out in high alkalinity samples, wherein it was found that the sensitivity of this method effectively remained unchanged. Monochloramine was also quantified in the presence of common interferents (copper, phosphate and iron) which had no significant impact on the analysis

scholarly journals Electrochemical Detection of Free-Chlorine in Water Samples Facilitated by In-Situ pH Control Using Interdigitated Microelectrodes

2020 ◽  
Author(s):  
Alan O'Riordan ◽  
Benjamin O'sullivan ◽  
Pierre Lovera ◽  
Ian Seymour ◽  
James Rohan
Keyword(s):  
Water Samples ◽  
Hypochlorous Acid ◽  
Control Method ◽  
Tap Water ◽  
Distribution Networks ◽  
Ph Control ◽  
Free Chlorine ◽  
Residual Chlorine ◽  
Solution Ph

Residual free-chlorine concentration in water supplies is a key metric studied to ensure disinfection. High residual chlorine concentrations lead to unpleasant odours and tastes, while low concentrations may lead to inadequate disinfection. The concentration is most commonly monitored using colorimetric techniques which require additional reagents. Electrochemical analysis offers the possibility for in-line analysis without the need for additional reagents. Electrochemical-based detection of chlorine is influenced by the solution pH, which defines the particular chlorine ionic species present in solution. As such, controlling the pH is essential to enable electrochemical based detection of residual chlorine in water. To this end, we explore the application of solid state interdigitated electrodes to tailor the in-situ pH of a solution while simultaneously detecting free-chlorine. Finite element simulations and subsequent electrochemical characterization, using gold interdigitated microelectrode arrays, were employed to explore the feasibility of an in-situ pH control approach. In practice, the approach converted residual chlorine from an initial mixture of two species (hypochlorous acid and hypochlorite ion), to one species (hypochlorous acid). Chlorine detection was shown in water samples using this exploratory method, resulting in a two-fold increase in signal response, compared to measurements without pH control. Finally, tap water samples were measured using the in-situ pH control method and the results showed excellent correlation (within experimental error) with a commercial instrument, demonstrating the efficacy of the developed technique. This work establishes the possibility of deploying an electrochemical based reagent-free, in-line chlorine sensor required for water distribution networks.

Electrochemical Detection of Free-Chlorine in Water Samples Facilitated by In-Situ pH Control Using Interdigitated Microelectrodes

2020 ◽  
Author(s):  
Alan O'Riordan ◽  
Benjamin O'sullivan ◽  
Pierre Lovera ◽  
Ian Seymour ◽  
James Rohan
Keyword(s):  
Water Samples ◽  
Hypochlorous Acid ◽  
Control Method ◽  
Tap Water ◽  
Distribution Networks ◽  
Ph Control ◽  
Free Chlorine ◽  
Residual Chlorine ◽  
Solution Ph

Residual free-chlorine concentration in water supplies is a key metric studied to ensure disinfection. High residual chlorine concentrations lead to unpleasant odours and tastes, while low concentrations may lead to inadequate disinfection. The concentration is most commonly monitored using colorimetric techniques which require additional reagents. Electrochemical analysis offers the possibility for in-line analysis without the need for additional reagents. Electrochemical-based detection of chlorine is influenced by the solution pH, which defines the particular chlorine ionic species present in solution. As such, controlling the pH is essential to enable electrochemical based detection of residual chlorine in water. To this end, we explore the application of solid state interdigitated electrodes to tailor the in-situ pH of a solution while simultaneously detecting free-chlorine. Finite element simulations and subsequent electrochemical characterization, using gold interdigitated microelectrode arrays, were employed to explore the feasibility of an in-situ pH control approach. In practice, the approach converted residual chlorine from an initial mixture of two species (hypochlorous acid and hypochlorite ion), to one species (hypochlorous acid). Chlorine detection was shown in water samples using this exploratory method, resulting in a two-fold increase in signal response, compared to measurements without pH control. Finally, tap water samples were measured using the in-situ pH control method and the results showed excellent correlation (within experimental error) with a commercial instrument, demonstrating the efficacy of the developed technique. This work establishes the possibility of deploying an electrochemical based reagent-free, in-line chlorine sensor required for water distribution networks.

scholarly journals Electrochemical detection of free-chlorine in Water samples facilitated by in-situ pH control using interdigitated microelectrodes

2020 ◽  
Vol 325 ◽  
pp. 128774 ◽  
Author(s):  
Ian Seymour ◽  
Benjamin O’Sullivan ◽  
Pierre Lovera ◽  
James F. Rohan ◽  
Alan O’Riordan
Keyword(s):  
Electrochemical Detection ◽  
Water Samples ◽  
Ph Control ◽  
Free Chlorine ◽  
Interdigitated Microelectrodes

scholarly journals Laboratory validation of an ozone device for recreational water treatment

2013 ◽  
Vol 11 (2) ◽  
pp. 267-276 ◽  
Author(s):  
Robert S. Donofrio ◽  
Sal Aridi ◽  
Ratul Saha ◽  
Robin Bechanko ◽  
Kevin Schaefer ◽  
...  
Keyword(s):  
Large Scale ◽  
Water Systems ◽  
Test System ◽  
Flow Dynamics ◽  
Recreational Water ◽  
Flow Rates ◽  
Bacteriophage Ms2 ◽  
Ozone Disinfection ◽  
Antimicrobial Effectiveness

Obtaining an accurate assessment of a treatment system's antimicrobial efficacy in recreational water is difficult given the large scale and high flow rates of the water systems. A laboratory test system was designed to mimic the water conditions and potential microbial contaminants found in swimming pools. This system was utilized to evaluate the performance of an in situ ozone disinfection device against four microorganisms: Cryptosporidium parvum, bacteriophage MS2, Enterococcus faecium, and Pseudomonas aeruginosa. The sampling regimen evaluated the antimicrobial effectiveness in a single pass fashion, with samples being evaluated initially after exposure to the ozone unit, as well as at points downstream from the device. Based on the flow dynamics and log reductions, cycle threshold (Ct) values were calculated. The observed organism log reductions were as follows: >6.7 log for E. faecium and P. aeruginosa; >5.9 log for bacteriophage MS2; and between 2.7 and 4.1 log for C. parvum. The efficacy results indicate that the test system effectively functions as a secondary disinfection system as defined by the Centers for Disease Control and Prevention's Model Aquatic Health Code.

In-situ Glycine Sensor Development Based ZnO/Al2 O3 /Cr2 O3 Nanoparticles

2018 ◽  
Vol 3 (41) ◽  
pp. 11460-11468 ◽  
Author(s):  
M. M. Alam ◽  
Abdullah M. Asiri ◽  
M. T. Uddin ◽  
M. A. Islam ◽  
Mohammed M. Rahman
Keyword(s):  
Sensor Development

scholarly journals A Theoretical and Experimental Study of Electrochemical pH Control at Gold Interdigitated Microband Arrays

2021 ◽  
Author(s):  
Bernardo Patella ◽  
Robert Daly ◽  
Ian Seymour ◽  
Pierre Lovera ◽  
James Rohan ◽  
...  
Keyword(s):  
Electrode Array ◽  
Ph Control ◽  
Reduction Peak ◽  
Solution Ph ◽  
Ph Indicator ◽  
Ph Change ◽  
Initial Ph ◽  
The Impact ◽  
Strong Acids

In electroanalysis, solution pH is a critical parameter that often needs to be adjusted and controlled for the detection of particular analytes. This is most commonly performed by the addition of chemicals, such as strong acids or bases. Electrochemical in-situ pH control offers the possibility for the local adjustment of pH at the point of detection, without additional reagents. FEA simulations have been performed to guide experimental design for both electroanalysis and in-situ control of solution pH. No previous model exists that describes the generation of protons at an interdigitated electrode array in buffered solution with one comb acting as a protonator, and the other as the sensor. In this work, FEA models are developed to provide insight into the optimum conditions necessary for electrochemical pH control. The magnitude of applied galvanostatic current has a direct relation to the flux of protons generated and subsequent change in pH. Increasing the separation between the electrodes increases the time taken for protons to diffuse across the gap. The final pH achieved at both, protonators and sensor electrodes, after 1 second, was shown to be largely uninfluenced by the initial pH of the solution. The impact of buffer concentration was modelled and investigated. In practice, the pH at the electrode surface was probed by means of cyclic voltammetry, i.e., by cycling a gold electrode in solution and identifying the potential of the gold oxide reduction peak. A pH indicator, methyl red, was used to visualise the solution pH change at the electrodes, comparing well with the model’s prediction

scholarly journals Peran Kontaminasi Kerak pada Diferensiasi Magma Pembentuk Batuan Vulkanik Sungai Ampalas, Mamuju, Sulawesi Barat

EKSPLORIUM ◽  
2020 ◽  
Vol 41 (2) ◽  
pp. 73
Author(s):  
Windi Anarta Draniswari ◽  
Sekar Indah Tri Kusuma ◽  
Tyto Baskara Adimedha ◽  
I Gde Sukadana
Keyword(s):  
Magma Mixing ◽  
Volcanic Rocks ◽  
Geochemical Characteristics ◽  
X Ray ◽  
Radioactive Mineral ◽  
Alkaline Feldspar ◽  
High Alkalinity ◽  
Preliminary Study ◽  
Xrf Analyses

ABSTRAK Anomali radiometri telah ditemukan di area Sungai Amplas pada bongkah batuan vulkanik. Nilai yang terukur dari spektrometer gama adalah 787 ppm eU dan 223 ppm eTh. Penemuan ini menarik untuk pengembangan eksplorasi. Studi lebih lanjut diperlukan untuk mengetahui karekteristik batuan pembawa mineral radioaktif dari sampel in-situ. Penelitian ini bertujuan untuk mengetahui karakteristik petrologi dan geokimia batuan vulkanik Ampalas sebagai studi awal untuk mengetahui proses akumulasi mineral radioaktif pada batuan vulkanik Ampalas. Metodologi yang digunakan meliputi pengamatan lapangan, pengambilan sampel batuan, analisis petrografi dan X-Ray Fluorescence (XRF). Batuan vulkanik ampalas tersusun atas ponolit, foidit, dan foid-syenit. Tekstur batuannya terdiri dari porfiritik, aliran, rim piroksen, zoning, pseudo-leusit, korosi, inklusi mafik, dan sieve. Karakteristik geokimia menunjukkan alkalinitas tinggi dan indikasi pengayaan mineral radioaktif yang tersebar dalam batuan. Proses magmatis yang berperan dalam pembentukan batuan vulkanik adalah fraksionasi kristal (fraksionasi leusit dan alkali felspar), asimilasi kerak kontinen, dan pencampuran magma. Interaksi antara magma dan kerak menyebabkan diferensiasi magma berkelanjutan yang menghasilkan akumulasi uranium dan torium lebih tinggi.ABSTRACT Anomalous radiometry has been found in Ampalas River Area on volcanic rock boulder. The values measured from gamma spectrometer are 787 ppm eU and 223 ppm eTh. This discovery is promising for exploration development. Further study need to figure the radioactive mineral bearing rock characteristic from in-situ samples. The research aim is to determine the petrology and geochemical characteristics of Ampalas volcanic rocks as preliminary study to find radioactive mineral accumulation process of Ampalas volcanic rocks. The methodologies are field observation, rock sampling, petrography, and X-Ray fluorescence (XRF) analyses. The Ampalas volcanic rocks consist of phonolite, phoidite, and phoid syenite. Their textures are porphyritic, flow, pyroxene rim, zoning, pseudo-leucite, corrosion, mafic inclusions, and sieve. The geochemical characteristics show high alkalinity and radioactive mineral enrichment disseminating on rock. The magmatic processes which play a significant role in radioactive mineral-bearing rocks formation are crystal fractionations (leucite and alkaline feldspar fractionations), continental crust assimilation, and magma mixing. Long interaction between magma and crust creates advanced magma differentiation causing higher uranium and thorium accumulation.  

scholarly journals Field Spectroscopy as a Tool for Enhancing Water Quality Monitoring in the ACE Basin, SC

2017 ◽  
pp. 41-55 ◽  
Author(s):  
Caitlyn C. Mayer ◽  
Khalid A. Ali
Keyword(s):  
Water Quality ◽  
South Carolina ◽  
Chlorophyll A ◽  
Algal Species ◽  
Water Quality Monitoring ◽  
Water Systems ◽  
Quality Monitoring ◽  
Least Squares Regression ◽  
Monitoring Methods

The Ashepoo, Combahee, Edisto (ACE) Basin in South Carolina is one of the largest undeveloped estuaries in the Southeastern United States. This system is monitored and protected by several government agencies to ensure its health and preservation. However, as populations in surrounding cities rapidly expand and land is urbanized, the surrounding water systems may decline from an influx of contaminants, leading to hypoxia, fish kills, and eutrophication. Conventional in situ water quality monitoring methods are timely and costly. Satellite remote sensing methods are used globally to monitor water systems and can produce an instantaneous synopsis of color-producing agents (CPAs), including chlorophyll-a, suspended matter (TSM), and colored-dissolved organic matter by applying bio-optical models. In this study, field, laboratory, and historical land use land cover (LULC) data were collected during the summers of 2002, 2011, 2015, and 2016. The results indicated higher levels of chlorophyll, ranging from 2.94 to 12.19 μg/L, and TSM values were from 60.4 to 155.2 mg/L between field seasons, with values increasing with time. A model was developed using multivariate, partial least squares regression (PLSR) to identify wavelengths that are more sensitive to chlorophyll-a (R2 = 0.49; RMSE = 1.8 μg/L) and TSM (R2 = 0.40; RMSE = 12.9 mg/L). The imbrication of absorption and reflectance features characterizing sediments and algal species in ACE Basin waters make it difficult for remote sensors to distinguish variations among in situ concentrations. The results from this study provide a strong foundation for the future of water quality monitoring and for the protection of biodiversity in the ACE basin.

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