Hydrogen Ion Production Research Articles

Real-Time Monitoring of Microbial Fermentation End-Products in Biofuel Production with Titrimetric Off-Gas Analysis (TOGA)

Abstract. Bioprocesses can be utilized for the sustainable production of biofuels and other value-added co-products. However, most bioprocesses targeting production of low value, high-volume products cannot yet compete with conventional technologies and require further development. On-line monitoring can help expedite bioprocess development by allowing dynamic study of microbial metabolism, optimal process control, and product quality assurance. Titrimetric off-gas analysis (TOGA) is an on-line sensor system that combines a membrane inlet mass spectrometer (MIMS) with on-line titration techniques to allow dynamic study of biological processes, including fermentation. In this study, TOGA was applied to fermentation of 2 g L -1 cellobiose with Clostridium thermocellum. Ethanol, CO 2 , H 2 , and total hydrogen ion production (HP) were quantified in real time. Concurrent off-line analysis was performed for verification using high-performance liquid chromatography and gas chromatography. Errors in the on-line data with respect to off-line analyses were found to be 4.8% ±3.7%, 7.1% ±3.5%, and 10.7% ±9.0% for H 2 , CO 2 , and ethanol, respectively. The discrepancies between the on-line and off-line analyses were not statistically significant with 95% confidence intervals. The titration system effectively maintained the process pH at 7.2 ±0.02 and also measured the hydrogen ion production (HP), which could be 88.4% accounted for in the production of CO 2 and organic acids, as determined by off-line analyses. The instrument was shown to be a viable on-line sensor that can monitor multiple physiologically relevant variables and contribute insight to the development and control of fermentation with C. thermocellum. The methodology can easily be extended to other fermentation processes.

Modelling the ion source for ITER NBI: from the generation of negative hydrogen ions to their extraction

The neutral beam injection (NBI) system for ITER is based on a large (Asource = 1.9 × 0.9 m2) negative hydrogen or deuterium ion source. In this source negative ions are produced in a low-pressure (pfill ≈ 0.3 Pa) plasma by conversion of atoms and protons on a caesiated molybdenum surface with low work function. Then the negative ions are transported through the plasma to the extraction system where extraction of these ions and co-extraction of electrons also take place. This paper describes the status of the modelling activities connected with the negative ion test facilities of IPP Garching. It is illustrated that these modelling activities constitute a strong support of the experimental activities connected with the development of the negative ion source for ITER NBI. Several numerical codes developed in the past years—in close collaboration with the experiment—and their results are introduced. Focus is laid on the production, transport and extraction of negative hydrogen ions and on the inevitable co-extraction of electrons.

Shortcut nitrification–denitrification in a sequencing batch reactor by controlling aeration duration based on hydrogen ion production rate online monitoring

The hydrogen ion production rate (HPR) and the pH of the aeration phase in a sequencing batch reactor (SBR) were simultaneously measured by a novel respirometric–titrimetric instrument. The results showed that HPR could indicate the end of ammonia oxidation with a greater accuracy and sensitivity than pH. An SBR was used to treat synthetic wastewater containing 360 mg/L chemical oxygen demand (COD) and 40 mg/L at 20°C with dissolved oxygen (DO) lower than 2.0 mg/L. Controlling the aeration duration based on HPR online monitoring, shortcut nitrification–denitrification was successfully performed for approximately two months with a stable nitrite accumulation rate (NAR) above 88%, and the COD and removal ratios were both higher than 90%. Based on the HPR online monitoring data, the estimated concentrations in nitrification were closely related to the measured concentrations, with a correlation coefficient of 0.9722, and the estimated values were lower than the measured values mainly because of the titration delay at the beginning of the aeration phase.

Fluorescence indicative pH drop in sonication

Sonication induces complex chemical and physical phenomena in solution, which attracted great attentions to discover the mechanisms behind these phenomena. One of these phenomena is the pH drop in sonication, which was usually attributed to the formation of nitrate and nitrite acid in sonication. However, the pH drop detected by electrodes was questioned since the sonication could enhance proton transfer on the surface of pH electrode, resulting in a false pH drop. Therefore, it is necessary to initiate a tour study on this issue. In this paper, we firstly investigate two new factors, namely CO2 dissolution and temperature, which have the possibility to induce the pH drop in sonication. The results demonstrate that both factors play a minor role on the pH drop. Then we employ pH sensitive dyes to replace the questioned pH electrode to detect the change of proton concentration in sonication. The results indicate that the pH drop is accompanied with the protonation of fluorescein, indicating production of hydrogen ions in sonication. The quantitative analysis of proton production suggests that the pH drop in sonication is mainly caused by the formation of hydrogen ions, which clarify the reason for the pH drop in sonication.

Development progresses of radio frequency ion source for neutral beam injector in fusion devices

A large-area RF (radio frequency)-driven ion source is being developed in Germany for the heating and current drive of an ITER device. Negative hydrogen ion sources are the major components of neutral beam injection systems in future large-scale fusion experiments such as ITER and DEMO. RF ion sources for the production of positive hydrogen (deuterium) ions have been successfully developed for the neutral beam heating systems at IPP (Max-Planck-Institute for Plasma Physics) in Germany. The first long-pulse ion source has been developed successfully with a magnetic bucket plasma generator including a filament heating structure for the first NBI system of the KSTAR tokamak. There is a development plan for an RF ion source at KAERI to extract the positive ions, which can be applied for the KSTAR NBI system and to extract the negative ions for future fusion devices such as the Fusion Neutron Source and Korea-DEMO. The characteristics of RF-driven plasmas and the uniformity of the plasma parameters in the test-RF ion source were investigated initially using an electrostatic probe.

Influence of pH on Hydrogen Absorption in Duplex Stainless Steel

With rising demands, oil and gas exploration of high-pressure high-temperature (HPHT) wells are increasing worldwide. Due to aggressiveness of HPHT environments, piping and equipments are constructed with high-strength corrosion resistant alloys (CRAs). Duplex stainless steel is one of the candidate alloys that offer high strength along with corrosion resistance. It possesses the advantages of both austenitic and ferritic stainless steels and hence, the name duplex or dual phase stainless steel. In order to control corrosion, cathodic protection is commonly being employed on the structures and equipment. Cathodic protection is accomplished by applying a direct current to the structure which causes the structure potential to change from the natural corrosion potential (Ecorr). The required cathodic protection current is supplied by sacrificial anode materials or by an impressed current system. Hydrogen embrittlement (HE) is an associated phenomenon, which results in the production of hydrogen ions, leading to its absorption in the protected metal and subsequent hydrogen embrittlement of metals and welds. To prevent this embrittlement, cathodic protection is closely studied in terms of finding the critical potential, pH, temperature etc. that does not cause hydrogen embrittlement. This paper describes the study carried out to find the role of pH on the absorption of hydrogen in Duplex Stainless steel. It has been observed that at a critical pH, hydrogen intake in the sample is very high, as compared to the pH below and above the critical pH. Critical pH observed for duplex stainless steel is a trade of between hydrogen evolution and absorption for given duplex structure.

Enhancement of negative hydrogen ion production in an electron cyclotron resonance source

In this paper, we present a method for improving the negative hydrogen ion yield in the electron cyclotron resonance source with driven plasma rings where the negative ion production is realized in two stages. First, the hydrogen and deuterium molecules are excited in collisions with plasma electrons to high-laying Rydberg and high vibration levels in the plasma volume. The second stage leads to negative ion production through the process of repulsive attachment of low-energy electrons by the excited molecules. The low-energy electrons originate due to a bombardment of the plasma electrode surface by ions of a driven ring and the thermoelectrons produced by a rare earth ceramic electrode, which is appropriately installed in the source chamber. The experimental and calculation data on the negative hydrogen ion generation rate demonstrate that very low-energy thermoelectrons significantly enhance the negative-ion generation rate that occurs in the layer adjacent to the plasma electrode surface. It is found that heating of the tungsten filaments placed in the source chamber improves the discharge stability and extends the pressure operation range.

Treatment of Acidosis in CKD

Metabolic acidosis (MA) in advanced CKD results from a progressive reduction in the capacity of the kidneys to generate sufficient ammonia to excrete the daily production of hydrogen ions (equivalent to approximately 1 mmol/kg body weight) leading to the formation of a new steady state at the cost of a reduction in blood pH. MA is a relatively common complication in patients with advanced CKD, particularly when GFR falls below 30 ml/min (1). MA adversely affects protein and muscle metabolism and bone turnover, compounding the mineral-bone disorder of uremia. In addition, MA is also associated with increased inflammatory mediators, insulin resistance, and corticosteroid and parathyroid hormone production. This may

Production and measurement of negative hydrogen ions in a FET-based RF ion source

Production and measurement of negative hydrogen ions in a FET-based RF ion source

Rotational and vibrational temperatures in a hydrogen discharge with a magnetic X-point

A novel plasma source with a magnetic X-point has been developed to probe an alternative for cesium-free negative hydrogen ion production. This study presents first results for the gas and vibrational temperatures in the source at 1 Pa and various RF powers. The temperatures are obtained from analysis of the intensity distribution of the molecular Fulcher-α bands. The gas temperature increases with the RF power, while the vibrational temperature remains constant in the studied range of RF powers. Both quantities show no appreciable spatial dependence. The obtained high values of the vibrational temperatures indicate a high population of the vibrational levels, favourable for the volume negative ion production. A theoretical concept indicates the presence of an optimum value for the vibrational temperature at which the negative hydrogen ion yield by volume processes has a maximum. Coincidently, the measured value is close to this optimum. This indicates that the novel concept can provide certain advantages compared to other sources based on volume production.

On the proton flux toward the plasma grid in a RF-driven negative hydrogen ion source for ITER NBI

The transport of protons in a RF-driven negative hydrogen ion source for ITER NBI was investigated by means of a 3D Monte Carlo transport code. As input for the code a consistent axial profile of the electrostatic potential for the complete ion source was constructed. The potential difference between the plasma generation volume and the plasma grid is in the range 10–20 V and depends on the RF power, the filling pressure and the plasma grid bias voltage. The mean free path for proton collisions with the background gas is in the range of several centimeters which means that the protons are noticeably decelerated and scattered. The velocity distribution function of the protons impinging the plasma grid resembles much more a low-temperature Maxwell distribution function than the high energetic proton beam which would be expected by looking only at the maximum value of the potential in the plasma generation volume. This finding is of high relevance for further analysis of the negative hydrogen ion production on the plasma grid surface as well as the ion transport and beam formation.

Spatial and seasonal variability of water-soluble ions in PM2.5 aerosols in 14 major cities in China

We analyzed PM2.5 aerosols from 14 major cities in China for concentrations of water-soluble (WS) major and trace elements (Na, Mg, Ca, K, Fe, Mn, Zn, Rb, Sr, Ba, Pb, S and Cl). The main focus was to examine patterns in spatial distribution and seasonal variability. Using principal component analysis, we identified three general sources for WS-elements in aerosols as anthropogenic, seasalts and fine dust particles originating from soils. The spatial patterns identified show that anthropogenic activity is the most important factor influencing the concentration of heavy metals in aerosols. Concentrations of WS-S, Zn and Pb were correlated with the locations of major industrial zones, and regulated by topography and seasonal weather patterns. We found higher WS-metals concentrations during the winter season, probably related to coal combustion in northern China. Moderate correlations of WS-S, Zn, Pb and Cl suggest that coal combustion releases. The seasonal pattern in WS-Fe concentrations shows the importance of acid precipitation events where coal combustion contributes to additional Fe (II) deposition. The findings of this study support the argument that WS-S in fine particles enhanced the production of hydrogen ions act to reduce the pH values of precipitation. Our interpretation of these spatial and seasonal patterns in WS-major and trace elements in aerosols highlights the need for continued research on trends in acidic deposition in major industrial cities in China.

Using short pulses to enhance the production rate of vibrationally excited hydrogen molecules in hydrogen discharge

Hydrogen discharges driven by the combined radio-frequency (rf)/short pulse sources are investigated using the particle-in-cell method. The simulation results show that the discharge driven additionally by the short pulse can enhance the electron density and modulate the electron energy to provide a better condition for negative hydrogen ion production than the discharge driven by the rf-only source.

Relationship between the weathering of clay minerals and the nitrification rate: a rapid tree species effect

We compared the properties of the clay mineral fraction and the composition of soil solutions in a Fagus sylvatica coppice (native forest) and four adjacent plantations of Pseudotsuga menziesii, Pinus nigra, Picea abies and Quercus sessiliflora planted in 1976. The results revealed changes of clay fraction properties due to tree species effect. Clay samples from Douglas fir and pine stands differ when compared to other species. Twenty-eight years after planting, we observed the following changes: a more pronounced swelling after citrate extraction and ethylene glycol solvation, a higher CEC and a smaller poorly crystallised aluminium content. All these changes affecting the clay fraction agreed well with soil solution analyses which revealed high NO3 −, H+ and Al concentrations under Douglas fir and pine. These changes were explained by a strong net nitrification under Douglas fir and pine stands when compared with other tree species. The higher NO3 − concentrations in soil solutions should be linked to the presence, type and activity of ammonia-oxiding bacteria which are likely influenced by tree species. The production of NO3 − in excess of biological demand leads to a net production of hydrogen ion and enhances the dissolution of poorly crystallised Al-minerals. Secondary Al-bearing minerals constituted the principal acid-consuming system in these soils. As a consequence, the depletion of interlayer spaces of hydroxyinterlayered minerals increases the number of sites for exchangeable cation fixation and increases CEC of the clay fraction. The dissolution of Al oxy-hydroxides explain the increase in Al concentrations of soil solutions under Douglas fir and pine stands when compared to other species. Nitrate and dissolved aluminium were conjointly leached in the soil solutions. A change in environmental conditions, like an introduction of tree species, enough modifies soil processes to induce significant changes in the soil mineralogical composition even over a period of time as short as some tens of years. Generally, mineral weathering has been considered to be very slow and unlikely to change over tens of years, resulting in few studies capable of detecting changes in mineralogy. This study appears to have detected changes in clay mineralogy during a period of 28 years after the planting of forest species. Our study represents a single location with a limited block design, but causes us to conclude that the observed changes could be widely representative. Where available, archived samples should be utilized and long-term experiments set up so that similar changes can be tested for and detected using more robust designs. The plausible hypothesis we present to explain apparent changes in clay mineralogy has strong relevance to the sustainable management of land.

Effects of adsorption and roughness upon the collision processes at the convertor surface of a plasma sputter negative ion source

Atomic collision processes associated with surface production of negative hydrogen ions (H(-)) by particle reflection at molybdenum surface immersed in hydrogen plasma have been investigated. To calculate sputtering yields of Cs, as well as energy spectra and angular distributions of reflected hydrogen atoms from molybdenum surface by H(+) ion and Cs(+) ion bombardments, a Monte Carlo simulation code ACAT (Atomic Collision in Amorphous Target) was run with the corresponding surface conditions. A fractal surface model has been developed and adopted to ACAT for evaluating the effect due to roughness of target material. The results obtained with ACAT have indicated that the retention of hydrogen atoms leads to the reduction in sputtering yields of Cs, and the surface roughness does largely affect the sputtering yields of Cs.

Numerical optimization of volume production efficiency of the JAERI 10 A ion source

In this paper, the particle-in-cell/Monte Carlo method simulation algorithm with independent intellectual property is described in-depth, and discharge properties of the JAERI 10 A multicusp ion source are investigated by using the algorithm. The effects of discharge parameters (such as air pressure, discharge electrode position, magnitute of the filter magnetic field, discharge voltage, etc) on volume production efficiency are analyzed. The results show that in order to obtain high volume production of negative hydrogen ions, filter magnetic field should not be too large, and the discharge voltage should not be too small, but the filter magnetic field and discharge voltage should be appropriately selected, and primarily regulating air pressure and discharge location simultaneously can optimize the ion source.

The three-dimensional numerical simulation study of H transmission and negative hydrogen ions production

The negative hydrogen ion source neutral particle transmission characteristics and the physical processes of the negative hydrogen ion extracted from plasma grid surface are analyzed. The influence of the extraction hole transfer rate which leads to hydrogen atom transmission is studied. A physical phenomenon of collision and reflection between H and different attribution conductor walls is explored. Then based on CHIPIC software platform, a full three-dimensional PIC-MCC simulation algorithm, in which the H transmission and the physical process of negative hydrogen ion production can be simulated, is successfully developed. It is verified by the simulation of JAEA 10A model. While the simulation reaches a steady state, the average energy of H is about 0.57 eV and H presents +Y drift. The non-uniform H beam bombarding the extraction wall leads to the spatial nonuniformity of negative hydrogen ions. These simulation results are consistent with those given in the literature, thereby verifying the reliability of the algorithm.

3D simulation optimization and design of multicusp ion source

In this paper, a permanent magnet of multicusp ion source is calculated in theory, using the binary collision model to deal with coulomb collision between electrons. Collision between electrons and hydrogen species is treated with the null-collision model. Therefore, the three-dimensional PIC-MCC simulation algorithm is developed. Two optimization design models of multicusp ion source, ET-60U, are simulated by the software. Also, the spatial distribution characteristics and the relevant issues of the volume negative hydrogen ion production rate of the two kinds of ion sources are explored. Finally, The basic idea about the design of the negative hydrogen ion source is proposed. indicating that appropriately regulating the magnetic field distribution of the multicusp ion source can produce uniform ion beam, and that appropriately adjusting the size of the extraction magnetic field and the ion source structure can obtain both the ion beam spatial uniformity and the high production rate.

Monitoring the nitrification and identifying the endpoint of ammonium oxidation by using a novel system of titrimetry

Based on the structure of the hybrid respirometer previously developed in our group, a novel implementation for titrimetry was developed, in which two pH electrodes were installed at the inlet and outlet of the measuring cell. The software capable of digital filtering and titration time delay correction was developed in LabVIEW. The hardware and software of the titrimeter and the respirometer were integrated to construct a novel system of respirometry-titrimetry. The system was applied to monitor a batch nitrification process. The obtained profiles of oxygen uptake rate (OUR) and hydrogen ion production rate (HPR) are consistent with each other and agree with the principle of the biological nitrification reaction. According to the OUR and HPR measurements, the oxidized ammonium concentrations were estimated accurately. Furthermore, the endpoint of ammonium oxidation was identified with much higher sensitivity by the HPR measurement. The system could be potentially used for on-line monitoring of biochemical reactions occurring in any kind of bioreactors because its measuring cell is completely independent of the bioreactor.

Effect of irradiation on nonlinear optical recirculation cavity performance

In applications such as the production of hydrogen ions for accelerators in spallation neutron sources, charge stripping of hydrogen ions using high-power lasers represents an attractive technical approach. The use of laser–ion interaction in conjunction with a laser recirculation cavity holds promise for improved efficiency, but the high-radiation environment raises concerns about the longevity of the key components of such a system, especially the nonlinear crystal used for frequency conversion. We present the results of an in-reactor irradiation experiment in which a sample beta-barium borate crystal has been irradiated with fast neutrons and gamma-rays, accompanied with the Monte Carlo analysis of the irradiation dose and its comparison with typical conditions at the Spallation Neutron Source at Oak Ridge National Laboratory. The results suggest that our design of the laser recirculation cavity exhibits a radiation hardness consistent with maintaining enhancement factors of the order of 10 over > 10 years, but a more detailed experimental study is needed to investigate the radiation hardness of cavity designs exhibiting greater enhancement factors.