Indiana University-Purdue University Indianapolis (IUPUI) / Improvised explosive devices (IEDs) are a global threat due to their destructive potential, the easy access to raw materials, and online instructions to manufacture them. These circumstances have led to an increase in the number of IEDs using potassium chlorate as an oxidizer. The standard methods to detect chlorate are mainly designed for laboratory-only testing. Thus, field instrumentation capable of detecting oxidizers from explosives fuel-oxidizers is critical for crime scene investigation and counterterrorism efforts (described in Chapter 1). We developed a paper-based sensor for the in-field detection of chlorate (described in Chapter 2). The sensor is low-cost, disposable, portable, and inexpensive to fabricate, and its flexibility features allow for surface sampling without sample destruction. The sensor has an electrodeposited molybdate sensing layer, as chlorate was reported to have a catalytic effect on the molybdate reduction. The chlorate detection relies on monitoring the change in redox activity of the molybdate sensing layer using different electroanalytical techniques. We effectively demonstrated the analytical performance of the sensor (Chapter 3), obtaining a limit of detection of 1.2 mM and a limit of quantification of 4.10 mM. We evaluated the selectivity of the sensor by testing other oxidizers, such as perchlorate and nitrate, which did not present any electrochemical activity with the molybdate sensing layer. Additionally, we performed an interferent study with sugar, commonly used as fuel in IEDs, and other common white household powders such as baking soda, flour, and corn starch and neither a false positive nor a false negative result was observed (Chapter 3). As bromate has been reported to have a stronger catalytic effect than chlorate on the redox activity of molybdate, the quantification of bromate was also explored, and a bromate sensor was developed using the findings of the chlorate sensor (Chapter 4). The reaction mechanism involved in the molybdate reduction was explored and discussed in Chapter 5. The capability of the sensor in detecting chlorate from combusted samples and post-blast samples was successfully demonstrated in Chapter 6, as well as the design of encased prototypes to allow for an in-field presumptive test, storage, and transport for in-laboratory confirmatory tests and compared the performance of the sensor to the available commercial tests.

No description available.

No description available.

The purpose of this investigation was to study the behavior during electrolysis of the waste from the ammonia recovery still of the Solvay Process. Data was obtained to show the effect on chlorate formation of the variables; temperature, concentration of electrolyte, and current concentration. In all the experimental runs, observations were made of the weight of calcium scale formed on the cathode surface end of the anode consumption. The temperature studies were made at 25°C, 45°C., and 60°C. The concentration studies were made with waste varying in composition from the concentration given by T.P. Hou ⁽¹²⁾ for the product of the ammonia recovery still to a concentration three times as great. The current concentration studies were made at current concentrations of 2, 4, and 6 amperes per liter. Three runs were made at 8 amperes per liter. / Master of Science

Microbial chlorate respiration plays an important role in the turnover of oxochlorates in nature and industrial waste management. This thesis deals with the characterization of the molecular components of chlorate respiration in Ideonella dechloratans. Chlorate respiration utilizes two soluble periplasmic enzymes, chlorate reductase and chlorite dismutase, to convert chlorate to chloride and oxygen. The genes encoding the enzymes participating in the chlorate degradation have been sequenced, and are found in close proximity, forming a gene cluster for chlorate metabolism. This work also includes the successful recombinant expression of three genes from Ideonella dechloratans. Two of the gene products, chlorite dismutase and the C subunit of chlorate reductase, participate in the chlorate respiration. The third gene, which is found close to the gene cluster for chlorate metabolism, encodes a soluble c-type cytochrome. The localization of the gene suggests the corresponding protein as a candidate for a role as electron donor to chlorate reductase. Also, the role of soluble periplasmic c cytochromes of Ideonella dechloratans in chlorate respiration was studied. At least one of the soluble c cytochromes was found capable of serving as electron donor for chlorate reduction. This c cytochrome, and several others, can also donate electrons to a terminal oxidase for subsequent reduction of oxygen, as required for the branched electron flow during chlorate respiration.

This licentiate thesis presents experimental studies concerning two parts of the electrochemical cell in the chlorate process: a cathode and an anode. Newly synthesized MnOx electrodes were investigated for the cathodic reaction, hydrogen evolution reaction (HER) in the chlorate process. In industry addition of toxic and carcinogenic chromium (VI) as sodium dichromate provides high efficiency. Here undesirable addition of sodium dichromate was avoided while high cathodic efficiency was achieved. Cathodic efficiency and selectivity towards HER, achieved by the MnOx electrodes annealed at different temperatures, were measured by means of mass spectrometry (MS).  The second study investigated oxygen evolution in the chlorate process, which is an anodic side reaction. The evolution of oxygen decreases anodic efficiency and also presents a safety risk due to occurrence of HER in the undivided cell. We followed the amount of produced oxygen by two types of the electrode TiRu, similar to that industrially used, and synthesized TiRuSnSb, by means of MS. The produced oxygen amount was compared to the amount produced by Pt. To our best knowledge, this was the first study that successfully disentangles three different sources of oxygen with good time resolution. Oxygen is produced by homogenous hypochlorite decomposition, heterogeneously by different catalysts present in the electrolyte solution and anodically during the electrolysis i.e. electrochemically. Different electrode materials catalyzed hypochlorite decomposition differently and led to a different volume of oxygen produced. / Denna licentiatavhandling redogör för experimentella studier av tvådelar av den elektrokemiska cell som används i kloratprocessen:katoden och anoden. Syntetiserade MnOx elektroder utvärderades för katodreaktionen,vätgasutveckling, i kloratprocessen. Industriellt tillsätts giftigt ochcancerogent krom(IV) som natriumdikromat för hög verkningsgrad. Denna studie uteslöt oönskad tillsats av natriumdikromat samtidigt som hög katodisk effektivitet erhölls. Katodisk effektivitet och selektivitet för vätgasutveckling, med MnOx elektroder,värmebehandlade vid olika temperaturer, uppmättes med masspektrometer. I den andra studien undersöktes syrgasutveckling i kloratprocessen,vilket är en anodisk sidoreaktion. Syrgasutvecklingen minskar den anodiska effektiviteten och utgör en säkerhetsrisk med anledning avden pågående vätgasutvecklingen i den odelade cellen. Vi uppmättemängden producerad syrgas med två olika elektroder TiRu, liknandeden som industriellt används, och syntetiserad TiRuSnSb, med masspektrometer. Den producerade syrgasmängden jämfördes med mängden producerat på Pt. Såvitt vi vet var detta den första studiesom särskiljer på tre olika syrgaskällor med god tidsupplösning. Syrgas produceras homogent av hypokloritsönderfall, heterogent av olika katalysatorer närvarande i elektrolyten och anodiskt vid elektrolys dvs. elektrokemiskt. Olika elektrodmaterial katalyserade hypokloritsönderfall olika och producerade olika volym syrgas. / <p>QC 2021-04-28</p>

The bacterium Ideonella dechloratans is a chlorate dissimilating bacteria that contains two enzymesnecessary for the dissimilation, chlorate reductase and chlorite dismutase. The means to regulate chlorite dismutase has previously been reported. However, the mechanism for chlorate reductase and its operon is still not know. The aim of this study was to develop the understanding of this complex mechanism. In order to investigate the potential important factors three intergenic sections upstream chlorate reductase was amplified. It was then inserted into a promoterless reporter vector that expresses the gene for β-galactosidase when a functioning promoter region is inserted. The activity of an inserted region can be measured using a β-galactosidase assay that hydrolyses a substrate resulting in a chromophore that can be measured using spectrophotometry. The three upstream regions inserted into the promoterless vector showed no increased activity compared to background signal from the backbone plasmid. This indicates that the regulation of the operon is complex. The host Escherichia coli strain RM101 may have been a bad host for the experimental setup or the selected region inserted into the reporter vector did not contain the sequences necessary for transcription and regulation. This work also suggests six potential promoter regions found in the intergenic section along with two possible binding sites for the NnrR transcription factor. / Bakterien Ideonella dechloratans är en kloratnedbrytande bakterie som innehåller två enzymer nödvändiga för nedbrytningen, kloratreduktas och kloritdismutas. Regleringen av kloritdismutas har tidigare rapporterats, dock är mekanismen för kloratreduktas och dess operon fortfarande okänt. Syftet med det här arbetet är att utveckla förståelsen för denna komplexa mekanism. För att undersöka de potentiellt viktiga faktorerna för regleringen amplifierades tre sekvenser uppströms genen för kloratreduktas. De fördes in i en reportervektor som saknar en funktionell promotor uppströms genen β-galaktosidas. Aktiviteten hos införda sekvenser kan mätas vid analys av aktivitet hos β-galaktosidas som hydrolyserar ett substrat vilket ger en produkt som är en kromofor som sedan kan mätas via spektrofotometri. De tre uppströmsregionerna som analyserades visade ingen ökad aktivitet jämfört med bakgrundssignalen från reportervektorn utan promotor. Detta indikerar att regleringen är komplex för kloratreduktas och dess operon. Värdcellen Escherichia coli RM101 kan ha varit en dålig värdstamför experimentuppställningen eller så saknades nödvändiga sekvenser för transkription och reglering i regionerna som infogats i reportervektorn. Det här arbetet föreslår sex möjliga promotorsekvenser som finns uppströms kloratreduktas tillsammans med två möjliga bindningsäten för transkriptionsfaktorn NnrR.

<p><!-- /* Font Definitions */ @font-face {font-family:Garamond; panose-1:2 2 4 4 3 3 1 1 8 3; mso-font-charset:0; mso-generic-font-family:roman; mso-font-pitch:variable; mso-font-signature:647 0 0 0 159 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:612.0pt 792.0pt; margin:72.0pt 90.0pt 72.0pt 90.0pt; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --></p><p>Several bacterial species are capable to use perchlorate and/or chlorate as an alternative electron acceptor in absence of oxygen. Microbial respiration of oxochlorates is important for biotreatment of effluent from industries where oxochlorates are produced or handled. One of these species, the Gram-negative <em>Ideonella dechloratans</em>, is able to reduce chlorate but not perchlorate. Two soluble enzymes, chlorate reductase and chlorite dismutase, participate in the conversion of chlorate into chloride and molecular oxygen. The present study deals with the electron transport from the membrane-bound components to the periplasmic chlorate reductase. Soluble <em>c</em> cytochromes were investigated for their ability to serve as electron donors to chlorate reductase. The results show that a 6 kDa <em>c </em>cytochrome serves as electron donor for chlorate reductase. This cytochrome also serves as electron donor for a terminal oxidase in the reduction of oxygen that is produced in the course of chlorate respiration. A gene encoding a soluble <em>c</em> cytochrome was found in close proximity to the gene cluster for chlorate reduction. This gene was cloned and expressed heterologously, and the resulting protein was investigated as a candidate electron donor for chlorate reductase. Electron transfer from this protein could not be demonstrated, suggesting that the gene product does not serve as immediate electron donor for chlorate reductase.</p><p> </p>

Several bacterial species are capable to use perchlorate and/or chlorate as an alternative electron acceptor in absence of oxygen. Microbial respiration of oxochlorates is important for biotreatment of effluent from industries where oxochlorates are produced or handled. One of these species, the Gram-negative Ideonella dechloratans, is able to reduce chlorate but not perchlorate. Two soluble enzymes, chlorate reductase and chlorite dismutase, participate in the conversion of chlorate into chloride and molecular oxygen. The present study deals with the electron transport from the membrane-bound components to the periplasmic chlorate reductase. Soluble c cytochromes were investigated for their ability to serve as electron donors to chlorate reductase. The results show that a 6 kDa c cytochrome serves as electron donor for chlorate reductase. This cytochrome also serves as electron donor for a terminal oxidase in the reduction of oxygen that is produced in the course of chlorate respiration. A gene encoding a soluble c cytochrome was found in close proximity to the gene cluster for chlorate reduction. This gene was cloned and expressed heterologously, and the resulting protein was investigated as a candidate electron donor for chlorate reductase. Electron transfer from this protein could not be demonstrated, suggesting that the gene product does not serve as immediate electron donor for chlorate reductase.

The production of chlorate, chlorine and sodium hydroxiderelies heavily on electrical energy, so that savings in thisarea are always a pertinent issue. This can be brought aboutthrough increased mass transfer of reacting species to therespective electrodes, and through increased catalytic activityand uniformity of current density distribution at theseelectrodes. This thesis will present studies involvingmathematical modelling and experimental investigations of theseprocesses. They will show the effect that hydrodynamicbehaviour has on the total current density and cell voltages,along with the effects on current density distributions andindividual overpotentials atthe respective electrodes. Primary, secondary and psuedo-tertiary current densitydistribution models of a chlor-alkali anode are presented anddiscussed. It is shown that the secondary model presentsresults rather similar to the pseudo-tertiary model, when thecurrent density distribution is investigated, although thepotential distribution differs rather markedly. Furthermore, itis seen that an adequate description of the hydrodynamicsaround the anode is required if the potential distribution, andthereby the prevalence of side-reactions, is to be reasonablepredicted. A rigorous tertiary current density distribution model ofthe chlorate cell is also presented, which takes into accountthe developing hydrodynamic behaviour along the height of thecell. This shows that an increased flowrate gives more uniformcurrent density distributions. This is due to the fact that theincreased vertical flowrate of electrolyte replenishes ioncontent at the electrode surfaces, thus reducing concentrationoverpotentials. Furthermore, results from the model lead to theconclusion that it is the hypochlorite ion that partakes in themajor oxygen producing side-reaction. A real-scale cross-section of a segmented anode-cathode pairfrom a chlorate cell was designed and built in order to studythe current density distribution in industrial conditions.These experiments showed that increased flowrate brought aboutmore even current density distributions, reduced cell voltageand increased the total current density. An investigation ofthe hydrodynamic effects on the respective electrodeoverpotentials shows the anode reactions being more favoured byincreased flowrate. This leads to the conclusion that theuniform current density distribution, caused by increasedflowrate, occurs primarily through decreasing the concentrationoverpotential at the anode rather than by decreasing thebubble-induced ohmic drop at the cathode. Finally, results from experiments investigating thebubble-induced free convection from a small electrochemicalcell are presented. These experiments show that Laser DopplerVelocimetry is the most effective instrument for investigatingthe velocity profiles in bubble-containing electrochemicalsystems. The results also show that the flow can transform fromlaminar to turbulent behaviour on both the vertical andhorizontal planes, in electrochemical systems where bubbles areevolved.