Laser-induced Breakdown Detection Research Articles

Thermodynamic Studies on the Hydrolysis of Trivalent Plutonium and Solubility of Pu(OH)3(am).

The temperature-dependent reaction properties of actinide elements are of particular interest in the safety assessment of high-level radioactive waste (HLRW) disposal systems. In this study, the hydrolysis of Pu(III) and the solubility of Pu(OH)3(am) were investigated at various temperatures (10-40 °C) in 0.1 M NaClO4. A strong reducing condition for maintaining the oxidation state of Pu(III) while slowly increasing the pH of the solution was realized by electrolysis. The formation constants of the first hydrolysis species, log *β1', and the solubility products of Pu(OH)3(am), log *Ks,0', at 10, 17, and 40 °C were experimentally determined using spectrophotometry, laser-induced breakdown detection, and radiometry. The enthalpy and entropy changes for these reactions were estimated using the van't Hoff equation. The first hydrolysis of Pu(III) is endothermic (ΔrHm° = 34.10 ± 4.48 kJ mol-1), and the dissolution of Pu(OH)3(am) is exothermic (ΔrHm° = -294.29 ± 23.05 kJ mol-1) with negative entropy changes. These thermodynamic data will contribute to improving the reliability of the safety assessment of HLRW disposal facilities and understanding the geochemical behavior of Pu under reducing or anoxic aqueous conditions at elevated temperatures.

Accountancy for intrinsic colloids on thorium solubility: The fractionation of soluble species and the characterization of solubility limiting phase

The extensive hydrolysis of tetravalent actinides leads to polynuclear formations through oxygen bridging facilitating the formation of colloids as end products. The pH, ionic strength has phenomenal effects on Thorium colloids formation. The quantitative estimation of colloids facilitates the fraction of soluble fraction into ionic, polymeric and colloidal forms of thorium. The colloids accountability and precipitate characterization explains the discrepancies in estimated solubility limits. The supernatants of long equilibrated (∼3 years) saturated thorium solution under various pH (5- 11) and ionic strengths (0–3 M NaClO4) were analysed by Inductively Coupled Plasma Mass Spectrometer (ICP-MS) and Ion Chromatography (IC) to determine total and ionic thorium respectively. Laser Induced Breakdown Detection (LIBD) was employed to determine the colloid size and concentrations. The precipitates were characterized by calorimetry and XRD to determine the solubility limiting phase. The results of pH, IC, ICP-MS, and LIBD measurements on the aged thorium samples are discussed with regard to the mechanism of the formation of thorium colloids. The results revealed the formation of colloids having particle size (10–40 nm) at concentrations (109-1011 particles/mL). The colloids accountancy resulted in estimated solubility products to 2–4 orders lower than their inclusion as soluble thorium. The soluble thorium was fractionated quantitatively into ionic, polymeric and colloidal forms of thorium. The precipitates formed are found to be semi amorphous.

Solvent effect on the acoustic detection of laser-induced breakdown

Interaction between pulsed laser beam and nanoparticles in solution results in the breakdown of dielectric medium which accompanies the plasma formation. Acoustic detection of laser-induced breakdown uses the information of the recorded acoustic signal for the quantification of colloids. To this date, laser-induced breakdown detection (LIBD) is mostly applied to water-based colloidal systems. This study aimed to give an insight of the solvent effect on the acoustic LIBD. Various solvents, namely methanol, ethanol, toluene, xylene, hexane, ethylene glycol, and oil, were subjected to acoustic LIBD. The results showed that the breakdown threshold energies for the non-water solvents were shifted from that of water; thus calibration curves for nanoparticles quantification might need some corrections. In addition, the effect of solvent dilution on acoustic LIBD was also studied by varying the concentration of methanol and ethanol. It was showed that solvent dilution resulted in the shifting of breakdown threshold energy to a lower value. This study indicated that careful analysis has to be taken when quantifying nanoparticles in non-water solvents using LIBD technique.

TRLFS study of hydrolyzed Eu(III) species

The hydrolysis of Eu(III) and Am(III) begins near neutral pH conditions, above which precipitation occurs due to low solubility. Careful sample characterization steps are a prerequisite for the speciation study of hydrolyzed Eu(III) complexes without the interference of colloidal particles or precipitation. Herein, the hydrolysis reaction of Eu(III) was studied using time-resolved laser fluorescence spectroscopy (TRLFS). Laser-induced breakdown detection was employed to monitor the presence of colloidal particles. The luminescence properties of Eu(III) and precipitated Eu(OH)3(s) were investigated and comparisons were made to those of aqua Eu3+. Parallel factor analysis was applied for the deconvolution of the TRLFS results. Both primary hydrolyzed Eu(III), EuOH2+ and precipitated Eu(OH)3(s) showed distinct luminescence spectral properties, including an enhanced hypersensitive luminescence peak (J = 2). An increased luminescence lifetime was observed for both EuOH2+ (τ = 130 ± 1 μs) and precipitated Eu(OH)3(s) (τ = 158 ± 7 μs) compared to that of aqua Eu3+ (τ = 112 ± 1 μs). A formation constant log*β1,1 of EuOH2+ at I = 0.1 M NaClO4 and 25 °C was measured to be –8.28 ± 0.22, which was converted to log*β°1,1 = –7.87 ± 0.22 at an infinitely diluted condition of I = 0 based on the specific ion interaction theory.

Detection of colloidal silver chloride near solubility limit

Detection of nanoparticles in solution has been made possible by several means; one of them is laser-induced breakdown detection (LIBD). LIBD is able to distinguish colloids of various sizes and concentrations. This technique has been used in several solubility studies. In this study, the formation of colloids in a mixed system of silver nitrate and sodium chloride was observed by acoustic LIBD. Silver chloride has low solubility limit, therefore LIBD measurement is appropriate. Silver and chloride solutions with equal concentrations, set at below and above the solubility of silver chloride as the expected solid product, were mixed and the resulting colloids were observed. The result of LIBD measurement showed that larger particles were present as more silver and chloride introduced. However, once the concentrations exceeded the solubility limit of silver chloride, the detected particle size seemed to be decreasing, hence suggested the occurrence of coprecipitation process. This phenomenon indicated that the ability of LIBD to detect even small changes in colloid amounts might be a useful tool in study on formation and stability of colloids, i.e. to confirm whether nanoparticles synthesis has been successfully performed and whether the system is stable or not.

Parallel-plate fracture transport experiments of nanoparticulate illite in the ultra-trace concentration range investigated by Laser-Induced Breakdown Detection (LIBD)

This study investigates the appropriateness of monodisperse carboxylated polystyrene spheres as clay colloid analogues. Colloid transport experiments using Na-illite are conducted within a parallel-plate fracture flow cell with an aperture of 0.75mm at pH 5 under low ionic strength (1mM NaCl) and laminar flow (7mL/h) conditions. The effects of collector surface material (Grimsel granodiorite or acrylic glass), fracture orientation and residence time on colloid retention are examined. In order to avoid full surface coverage effects, ultra-trace (30ppb) Na-illite colloid concentrations are used. Laser-induced breakdown detection is applied in order to detect and quantify the Na-illite colloids. The results are directly compared to the experiments of Stoll, et al. [1] who investigated the transport and surface interaction of carboxylated polystyrene spheres (25 and 1000nm diameter) using the same experimental setup and conditions. It is concluded that polystyrene spheres are no ideal analogue to predict the mobility and transport behavior of a polydisperse clay colloid suspension. Despite the higher solid density, the Na-illite colloids show higher mobility compared to the polystyrene spheres without significant impact of surface roughness or gravity. The platelet shape, the non-uniform surface charge distribution and slower sedimentation may account for the observed differences.

Laser-induced photo emission detection: data acquisition based on light intensity counting

Laser Induced Breakdown Detection (LIBD) is one of the quantification techniques for colloids. There are two ways of detection in LIBD: optical detection and acoustic detection. LIBD is based on the detection of plasma emission due to the interaction between particle and laser beam. In this research, the changing of light intensity during plasma formations was detected by a photodiode sensor. A photo emission data acquisition system was built to collect and transform them into digital counts. The real-time system used data acquisition device National Instrument DAQ 6009 and LABVIEW software. The system has been tested on distilled water and tap water samples. The result showed 99.8% accuracy by using counting technique in comparison to the acoustic detection with sample rate of 10 Hz, thus the acquisition system can be applied as an alternative method to the existing LIBD acquisition system.

Study on acoustic detections of Nd:YAG laser induced breakdown at different wavelengths

Laser-induced breakdown detection (LIBD) is among many techniques utilizing laser beam to characterize nanoparticles in solution. It is based on the detection of plasma formation resulted from the interaction between particles and laser beam. In acoustic LIBD, the acoustic signal which accompanies the plasma formation is detected by a microphone. In this study, a 1064 nm pulsed laser was used as the laser source for LIBD system instead of the frequently used 532 nm. The presence of colloids in filtered and unfiltered water was investigated using the new system and the result was compared with those from conventional system. The S-curves from 1064 nm system showed similar trend with S-curves from 532 nm system. The presence of larger nanoparticles in unfiltered water resulted in lower breakdown threshold energy. However, the breakdown threshold energy of both filtered and unfiltered water was much higher in the 1064 nm LIBD system. The shifting was attributed to the high absorbance of water at 1064 nm. This research proved the possibility of using 1064 nm pulsed Nd:YAG laser as an alternative wavelength source for LIBD system, nevertheless various setup arrangement might be needed.

In-situ characterization of nanoparticle beams focused with an aerodynamic lens by Laser-Induced Breakdown Detection.

The Laser-Induced Breakdown Detection technique (LIBD) was adapted to achieve fast in-situ characterization of nanoparticle beams focused under vacuum by an aerodynamic lens. The method employs a tightly focused, 21 μm, scanning laser microprobe which generates a local plasma induced by the laser interaction with a single particle. A counting mode optical detection allows the achievement of 2D mappings of the nanoparticle beams with a reduced analysis time thanks to the use of a high repetition rate infrared pulsed laser. As an example, the results obtained with Tryptophan nanoparticles are presented and the advantages of this method over existing ones are discussed.

Laser-induced breakdown detection of temperature-ramp generated aggregates of therapeutic monoclonal antibody

The detection and characterization of protein aggregation is essential during development and quality control of therapeutic proteins, as aggregates are typically inactive and may trigger anti-drug-antibody formation in patients. Especially large multi-domain molecules, such as the important class of therapeutic monoclonal antibodies (mAbs), can form various aggregates that differ in size and morphology. Although particle analysis advanced over the recent years, new techniques and orthogonal methods are highly valued. To our knowledge, the physical principle of laser-induced breakdown detection (LIBD) was not yet applied to sense aggregates in therapeutic protein formulations. We established a LIBD setup to monitor the temperature-induced aggregation of a mAb. The obtained temperature of aggregation was in good agreement with the results from previously published temperature-ramped turbidity and dynamic light scattering measurements. This study demonstrates the promising applicability of LIBD to investigate aggregates from therapeutic proteins. The technique is also adaptive to online detection and size determination, and offers interesting opportunities for morphologic characterization of protein particles and impurities, which will be part of future studies.

Colloidal nanoparticles produced from Cu metal in water by laser ablation and their agglomeration

Abstract Colloidal nanoparticles were prepared from Cu metal in water without any surfactant using a simple one-step laser ablation process with 532 nm Nd-YAG beam irradiation. A surface plasmon band of Cu nanoparticles near 580 nm was not observed; instead, oxidation of the Cu colloidal nanoparticles was noticed. This seems to be due to the partially oxidized copper oxides through the route Cu→Cu2O→CuO. Around 10-nm sized colloidal nanoparticles were agglomerated as a result of oxidation according to the time elapsed, and their sizes were increased to near 200 nm. The agglomeration was confirmed by not only images from transmission electron microscopy but also the long-term observation of the particle size distribution using photon correlation spectroscopy, laser-induced breakdown detection, and field flow fractionation.

Influence of dispersion agents on particle size and concentration determined by laser-induced breakdown detection

Laser-induced breakdown detection (LIBD) is a very promising analytical technique to determine the size and the concentration of nanoparticles (NPs) in aqueous suspensions. The measurement principle is based on the formation of individual plasma events selectively produced when a pulsed, focused laser beam hits a NP. The breakdown probability (BDP) is defined as the ratio of the number of plasma events detected to the total number of laser pulses applied. Energy curves are established by recording the BDP as a function of the laser energy which is increased in a stepwise manner. The size and the concentration of NPs in aqueous suspensions can be extracted from recorded energy curves. Although several studies have already documented the potential of the LIBD technique to detect NPs at trace concentrations in aqueous suspensions, the effect of dissolved matrix constituents (e.g. dispersion agents, which are frequently used to stabilize NPs in suspension) on the LIBD signal has not been addressed, yet.We therefore recorded energy curves of ultrahigh purity (UHP) water and NP suspensions both spiked with different dispersion agents at different concentrations. An increasing shift of the energy curves towards lower energies was observed with increasing concentrations of dispersion agents. The LIBD-derived size of the NPs was less affected by the presence of dispersion agents than the LIBD-derived particle number concentrations, which deviated by up to 300% from the expected values. The effects on the calculated concentrations were most pronounced at low (2·107particlesmL−1) NP concentrations and at higher NP concentrations (3·108particlesmL−1), the effect of the dispersion agents on the energy curves became negligible. These results show that dissolved matrix constituents substantially affect LIBD measurements, especially at low NP concentrations.

Application of laser-induced breakdown-detection as a sensitive detector for UF membrane surrogate challenge tests

Characteristics of ultrafiltration membranes with respect to the removal of nanoscale particles can be determined by surrogate challenge tests (SCTs). Key elements of a successful SCT are the selection of a suitable surrogate and a reliable quantification method. A major challenge when using nanoparticles as surrogates is their quantification in the filtrate, since commonly used particle detection methods are often lacking in sensitivity. The applicability of laser-induced breakdown-detection (LIBD) as a monitoring tool for SCTs has therefore been evaluated. The SCTs were carried out using polystyrene (PS) and silicate particles spiked into ultrapure water and into bank filtrate. Nanoparticles were detectable down to 10 nm and, depending on the material, down to a few ng/L. The nominal pore-size of the ultrafiltration membrane could be confirmed during the tests, demonstrating the suitability of LIBD as a highly sensitive monitoring technique for SCTs.

Laser-Induced Breakdown-Detection for reliable online monitoring of membrane integrity

The applicability of Laser-Induced Breakdown-Detection (LIBD) as an online membrane integrity monitoring system during ultrafiltration processes has been evaluated by linking a laboratory-scale membrane filtration test system to acoustic LIBD instrumentation. The results demonstrate that LIBD is a sensitive and reliable indirect online system suitable for testing and monitoring membrane integrity in ultrafiltration processes. Particles present in the filtrate can be detected continuously online using a fixed laser pulse energy (continuous mode). The LIBD monitoring system proved to be sensitive to nanoscale particles leaching through breaches in a membrane. In continuous mode 20nm particles could be detected at concentrations as low as a few ng/L. This is superior in terms of both minimum detectable particle size and minimum concentrations to the turbidity measurement and particle counting methods that are commonly used for continuous online monitoring. Depending on the feed water characteristics and the membrane used, the LIBD system can be adjusted to specific processes by varying the measurement settings. Particle size distributions in the feed and filtrate can also be determined through non-continuous online LIBD measurements by varying the laser pulse energies (non-continuous mode), thus allowing the particle retention characteristics of the membrane to be analyzed.

Formation of surface mediated iron colloids during U(VI) and nZVI interaction

We investigated that removal of aqueous U(VI) by nano-sized Zero Valent Iron (nZVI) and Fe(II) bearing minerals (controls) in this study. Iron particles showed different U(VI) removal efficiencies (Mackinawite: 99%, green rust: 95%, nZVI: 91%, magnetite: 87%, pyrite: 59%) due to their different PZC (Point of Zero Charge) values and surface areas. In addition, noticeable amount of surface Fe(II) (181 ) was released from nZVI suspension in 6 h and it increased to 384 in the presence of U(VI) due to ion-exchange of U(VI) with Fe(II) on nZVI surface. Analysis of Laser-Induced Breakdown Detection (LIBD) showed that breakdown probabilities in both filtrates by 20 and 200 nm sizes was almost 24% in nZVI suspension with U(VI), while 1% of the probabilities were observed in nZVI suspension without U(VI). It indicated that Fe(II) colloids in the range under 20 nm were generated during the interaction of U(VI) and nZVI. Our results suggest that Fe(II) colloids generated via ion-exchange process should be carefully concerned during long-term remediation site contaminated by U(VI) because U could be transported to remote area through the adsorption on Fe(II) colloids.

Gas phase temperature measurements in the liquid and particle regime of a flame spray pyrolysis process using O2-based pure rotational coherent anti-Stokes Raman scattering

For the production of oxide nanoparticles at a commercial scale, flame spray processes are frequently used where mostly oxygen is fed to the flame if high combustion temperatures and thus small primary particle sizes are desired. To improve the understanding of these complex processes in situ, noninvasive optical measurement techniques were applied to characterize the extremely turbulent and unsteady combustion field at those positions where the particles are formed from precursor containing organic solvent droplets. This particle-forming regime was identified by laser-induced breakdown detection. The gas phase temperatures in the surrounding of droplets and particles were measured with O(2)-based pure rotational coherent anti-Stokes Raman scattering (CARS). Pure rotational CARS measurements benefit from a polarization filtering technique that is essential in particle and droplet environments for acquiring CARS spectra suitable for temperature fitting. Due to different signal disturbing processes only the minority of the collected signals could be used for temperature evaluation. The selection of these suitable signals is one of the major problems to be solved for a reliable evaluation process. Applying these filtering and signal selection steps temperature measurements have successfully been conducted. Time-resolved, single-pulse measurements exhibit temperatures between near-room and combustion temperatures due to the strongly fluctuating and flickering behavior of the particle-generating flame. The mean flame temperatures determined from the single-pulse data are decreasing with increasing particle concentrations. They indicate the dissipation of large amounts of energy from the surrounding gas phase in the presence of particles.

Release of Nanoparticles from Ion Exchange Resins and Their Detection

Nanoparticles released from commercial ion exchange resins were analyzed by laser-induced breakdown detection (LIBD). It was shown that virgin resins release a considerable amount of nanoparticles which may harm sensitive production lines, if the resins are used without proper pretreatment. Particle release is reduced to below 1 ppb after regeneration and rinsing of the resins. However, the nanoparticle concentration can still be detected quantitatively by LIBD.

이동식 레이저 유도 파열 검출 장치를 이용한 KURT 지하수 내 콜로이드 나노 입자 검출

한국원자력연구원 내 지하 처분 연구시설(KURT)에서 채취한 지하수에 존재하는 나노 콜로이드 입자의 크기 및 농도를 현상에서 조사하기 위해 이동식 레이저 유도 파열 검출 장치를 개발하였다. 제작한 장치는 CCD 카메라를 이용하여 레이저 유도 플라즈마가 발생한 위치를 2-차원 영상으로 기록함으로써 광학적으로 입자의 크기를 결정할 수 있다. 크기가 정확히 알려진 폴리스틸렌 표준 입자를 이용하여 입자 크기 측정용 검정 곡선 (calibration curve)을 구했고, 이를 이용하여 지하 처분 연구시설에서 채취한 지하수 내 콜로이드 입자의 크기를 측정하였다. 지하수 내 존재하는 콜로이드 입자의 평균 크기는 <TEX>$108{\pm}26$</TEX> nm 임을 보였고, 농도는 50 ppb 이하인 것으로 추정하였다. A mobile laser-induced breakdown detection (LIBD) system was developed for the field measurement of the size and concentration of aquatic colloidal nanoparticles sampled from Korea Atomic Energy Research Institute Underground Research Tunnel (KURT). The established LIBD apparatus is based on the optical detection of a laser-induced plasma by means of a two-dimensional optical imaging method for determining the size of nanoparticle. Calibration curve for determining the size of nanoparticle was obtained from the polystyrene reference particles of a well-defined size. The first direct application was made at KURT for investigating the particle sizes in groundwater. By comparing the size of particles in groundwater with the sizes of reference particles, the mean particle size of approximately <TEX>$108{\pm}26$</TEX> nm with the concentration lower than 50 ppb was determined.

Study on The Measurement of Corrosion Product Concentration in The Feed Water System of A Power Plant

(Received August 8, 2011; Revised August 29, 2011; Accepted August 29, 2011)The iron oxide particles could be resulted from the corrosion of the circulating water system of a power plant.Because it may be one of the trouble materials which affect the power generation efficiency due to the depositionon steam generator tube and turbine blade, the continuous observation of its concentration is very important.The laser induced break-down detection (LIBD) technology was applied to monitor continuously the concentrationof corrosion products with the detection limit of ppb level. The measurement system consists of a Nd:YAG pulsed laser, a polarizing beam splitter, a flow-type sample cell, an acoustic emission sensor, a high speed data acquisition board, a personal computer, etc.. The performance test results confirmed that this technology can be effective to monitor the corrosion product concentration of the circulating water system of a power plant.

Development of a mobile fast-screening laser-induced breakdown detection (LIBD) system for field-based measurements of nanometre sized particles in aqueous solutions

Laser-induced breakdown detection (LIBD) is a promising method to detect trace amounts of nanoparticles (NP, <100 nm) in aqueous suspensions. Based on available systems, we developed a mobile LIBD, designed for on-site and on-line measurements. We used the energy ratio of every laser pulse before and after passing the laser beam through the aqueous sample as a new method to detect laser-induced plasma events. The particle size and the particle number density are derived from recorded energy curves. Our LIBD is operated with a Nd:YAG laser at 100 Hz significantly reducing the measurement times compared to other LIBD systems operated at 20 Hz and increasing the capabilities for monitoring purposes. Long-term experiments on water samples revealed losses of NP up to 75% in 15 mL and 35% in 5 L sample containers after 3 months. The size of the particles remained constant (5 L) or slightly decreased (15 mL) indicating significant adsorption of NP to the walls of the sampling containers. Furthermore, we monitored the NP content of water after different purification steps at a drinking water plant (Maennedorf, Lake Zurich, Switzerland). Activated carbon filtration resulted in an increase of the particle size from approximately 20 nm to approximately 75 nm possibly caused by the release of organic fragments derived from the biology within the activated carbon tank. After the final ultrafiltration step the particle size was around 10 nm in agreement with the nominal cutoff of 100 kDa of the membrane. The results underline the strength of a fast-screening LIBD to detect relative changes in NP size and concentration.