Non-volatile Ions Research Articles

Evaluation of semi-volatile contaminant transport in a novel, gas-tight direct contact membrane distillation system

A first-of-its-kind, gas-tight MD system was designed to provide insight into the dynamic transport of semi-volatile contaminants over time by closing the mass balance for each contaminant. Testing with non-volatile ions was used to confirm the integrity of the test system and sampling procedures. Non-volatile contaminants had consistently high rejection rates (≥99%) for all analytes tested. For the most hydrophobic semi-volatile contaminants, sorption to the membrane and polymeric components within the system played a significant role in their fate. Less hydrophobic semi-volatile contaminants reached a pseudo-equilibrium governed largely by contaminant volatility, as predicted by Henry's Law. Rejection of semi-volatile nitrosamines varied from −96 to 88%, demonstrating significant variation in behavior even within the same contaminant class. Results suggest that transport of semi-volatile contaminants in MD was consistent with a pseudo-equilibrium partitioning process and was highly correlated with contaminant volatility (R2=0.934 for the combined data set). These results have implications for treatment of complex source waters where an understanding of the transport of volatile components is needed even if treatment objectives are focused on nonvolatile components.

Self-organized surface ripple pattern formation by ion implantation

Ion induced ripple pattern formation on solid surfaces has been extensively studied in the past and the theories describing curvature dependent ion erosion as well as redistribution of recoil atoms have been very successful in explaining many features of the pattern formation. Since most experimental studies use noble gas ion irradiation, the incorporation of the ions into the films is usually neglected. In this work we show that the incorporation or implantation of non-volatile ions also leads to a curvature dependent term in the equation of motion of a surface height profile. The implantation of ions can be interpreted as a negative sputter yield; and therefore, the effect of ion implantation is opposite to the one of ion erosion. For angles up to about 50°, implantation of ions stabilizes the surface, whereas above 50°, ion implantation contributes to the destabilization of the surface. We present simulations of the curvature coefficients using the crater function formalism and we compare the simulation results to the experimental data on the ion induced pattern formation using non-volatile ions. We present several model cases, where the incorporation of ions is a crucial requirement for the pattern formation.

A dual cryogenic ion trap spectrometer for the formation and characterization of solvated ionic clusters.

A new experimental approach is presented in which two separate cryogenic ion traps are used to reproducibly form weakly bound solvent clusters around electrosprayed ions and messenger-tag them for single-photon infrared photodissociation spectroscopy. This approach thus enables the vibrational characterization of ionic clusters comprised of a solvent network around large and non-volatile ions. We demonstrate the capabilities of the instrument by clustering water, methanol, and acetone around a protonated glycylglycine peptide. For water, cluster sizes with greater than twenty solvent molecules around a single ion are readily formed. We further demonstrate that similar water clusters can be formed around ions having a shielded charge center or those that do not readily form hydrogen bonds. Finally, infrared photodissociation spectra of D2-tagged GlyGlyH(+)⋅(H2O)1-4 are presented. They display well-resolved spectral features and comparisons with calculations reveal detailed information on the solvation structures of this prototypical peptide.

Determination of pharmaceutically related compounds by suppressed ion chromatography: IV. Interfacing ion chromatography with universal detectors

This work forms the final part of a study investigating gradient elution ion-exchange chromatography of pharmaceutically relevant compounds, aiming at achieving complementary selectivity to reversed-phase HPLC. In this study the coupling of three universal detectors (electro-spray ionisation mass spectrometer (ESI-MS); corona charged aerosol detector (CAD); and evaporative light scattering detector (ELSD)) to suppressed IC using complex elution profiles with potassium hydroxide eluents is demonstrated. The non-volatile ions were removed from the eluent by the suppressor prior to detection, thus allowing a stable detector response, especially with the prototype electrolytic suppressor. The detector response for ten weakly anionic pharmaceuticals followed the expected models and the limits of detection obtained were not compromised by the use of a suppressor, yielding values below 50ng/mL with MS, low to sub μg/mL levels with CAD and 2–20μg/mL with ELSD (25μL injections). When coupled to MS and CAD, the prototype electrolytic suppressor showed percentage relative standard deviations (%RSDs) in peak areas of 0.4–2.5% on average, compared to the chemical suppressor which yielded 1.5–3 fold higher %RSD values for the test analytes. The prototype electrolytic suppressor also generally exhibited wider linear response ranges than the chemical suppressor.

Collecting Exhaled Breath Condensate (EBC) with Two Condensers in Series: A Promising Technique for Studying the Mechanisms of EBC Formation, and the Volatility of Selected Biomarkers

Exhaled breath condensate (EBC) consists mainly of water, but also contains semivolatile and nonvolatile compounds. The aim of this study was to develop a system in which two condensers are simultaneously used in series to clarify the mechanisms of EBC condensation. Two aliquots of EBC (EBC1 and EBC2) were collected from 20 asymptomatic smokers and 20 healthy young nonsmokers using a specifically designed device having two condensers in series in which total volume, hydrogen peroxide (H(2)O(2)), ammonium (NH(4)(+)), and conductivity before and after lyophilization were measured. Water, NH(4)(+) levels and conductivity before lyophilization were significantly lower in the EBC2 than in the EBC1 of smokers and nonsmokers; the contrary was true for H(2)O(2) levels. Almost all nonvolatile salts were collected in the first condenser, because more than 50% of postlyophilization conductivity was below the detection limit in EBC2. The recovery of volatile molecules and their derivatives (water and NH(4)(+)) was partial in the first condenser, but appreciable amounts of both were measured in the second; however, the condenser immediately in contact with exhaled air was more efficient in terms of water, NH(4)(+) and conductivity before lyophilization. On the contrary, nonvolatile ions (conductivity after lyophilization) were mainly collected in the first condenser. Finally, the behavior of H(2)O(2) cannot be explained on the basis of its chemical and physical properties, and the most probable explanation is that some was byproduced by a radical reaction in the gas phase or during the condensation process in water.

Transition from tungsten erosion to carbon layer deposition with simultaneous bombardment of tungsten by helium and carbon

Simultaneous bombardment of tungsten layers with helium and carbon ions leads to both erosion of tungsten and implantation of carbon. The underlying processes have been investigated numerically and experimentally as a function of the carbon fraction in the incident ion flux for ion energies in the kilo electron volt range. Tungsten layers were deposited on polished single-crystal silicon substrate by magnetron sputter deposition to eliminate the influence of surface roughness on the experimental results. The fluence-dependent dynamics of the surface composition was measured in situ by ion beam analysis. The given projectile-target system is subject only to kinematic processes, and is therefore particularly suitable for benchmarking of purely kinematic simulations based on the binary-collision approximation, as implemented in the TRIDYN code. TRIDYN calculations match the experimental results very well, which demonstrates the validity of the kinematic description. In particular, the simulations allow us to predict the change of surface composition by bombardment with gaseous and nonvolatile ions, as well as the transition point from W erosion to C deposition as function of the carbon fraction in the incident ion flux.

Tungsten sputtering and accumulation of implanted carbon and deuterium by simultaneous bombardment with D and C ions

Sputtering of tungsten by simultaneous incidence of gaseous and non-volatile ions is an important field of research for nuclear fusion with magnetically confined plasmas. In order to investigate the underlying processes in detail, W layers deposited on graphite and Si substrates have been irradiated simultaneously with beams of 12keV C2- and 9keV D3+ ions. The dynamics of W sputtering as well as the accumulation of implanted C and D was studied in-situ by ion beam analysis (IBA) using 2.5MeV 3He+ ions. In this work, particularly the sputter yield of W and the implantation of C and D as a function of the C fraction in the incident flux is discussed. Comparison of experimental data to TRIDYN simulations reveal a strong contribution of surface roughness to W sputtering and C implantation. In comparison to the influence of roughness, the contribution of chemical effects appears negligible.

Improved characterisation of inorganic components in airborne particulate matter

We set up a microanalytical procedure for non-volatile ions by ion chromatography (IC) and for elements by energy-dispersive X-ray fluorescence (ED-XRF) and inductively coupled plasma optical emission spectroscopy (ICP-OES). We analysed NO3, SO4, NH4, Na, Mg, Ca, Fe, S, Zn, As, Cd, Cu, Mn, Ni, Pb, Sb, Se, Ti, and V. The use of complementary techniques yields reliable data for both trace and crustal elements, overcoming the analytical restrictions characteristic of the individual techniques. Some elements determined by two or by all three techniques can be used as data quality markers. The application of the procedure to a short PM2.5 monitoring campaign is also described, aimed to the identification of fireworks tracers.

Determination of metals, metalloids and non-volatile ions in airborne particulate matter by a new two-step sequential leaching procedure: Part A: Experimental design and optimisation

The optimisation of a micro-analytical two-step sequential leaching procedure for the determination of non-volatile ions (NO 3 −, SO 4 2−, Cl −, Na +, Mg 2+, NH 4 + and Ca 2+) and of 17 elements (Al, As, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Pb, S, Se, V, Zn, Sb, Si and Ti) in two fractions—extract and residue—on the same sample of air particulate matter is described. The two-step method was tested on the SRM NIST 1648 for equivalence with two reference methods, the EMEP procedure for ions extraction and the EN 12341 standard for the elemental determination of the PM 10 and is suitable for application to small sample amounts (less than 1 mg of particulate matter is needed), i.e. those collected by daily low volume filter-sampling. Performance times of the procedure were optimised to meet the target of routine application for large scale monitoring samples. A single ultrasonic-assisted extraction of air particulate matter is performed in 0.01 M acetate buffer at pH 4.5, followed by IC ions analysis and ICP-OES elemental analysis of the extract and by ICP-OES elemental analysis of the mineralized residue after dissolution by microwave-assisted digestion with a HNO 3/H 2O 2 mixture. Using a pH buffered extracting solvent was preferred to water or diluted acid solutions to improve the reproducibility of metals extraction with respect to existing leaching methods; the influence of pH, nature and concentration of the buffer solution and extraction time on analytes concentration in the extract is discussed. Values of ions extraction and elements recoveries resulted fairly equivalent with those obtained by the reference methods. The study was also extended to some non-certified elements (Mg, S, Sb, Si and Ti) for their environmental significance. Elements recoveries were obtained as sum of the extract and residue fractions and were comparable with those obtained by direct dissolution. Standard deviations were within 10% for almost all detected ions and elements.

Determination of metals, metalloids and non-volatile ions in airborne particulate matter by a new two-step sequential leaching procedure: Part B: Validation on equivalent real samples

Due to the lack of proper standard materials for airborne particulate matter collected on filters, a validation scheme was developed, which is here described, to the aim of testing the application of leaching procedures performing both ions and elemental determinations on real samples of airborne particulate matter collected on filters. The scheme has been developed on a two-step leaching method (extraction in acetate buffer and acid dissolution of residue) previously developed by authors and consists of two series of tests to be run on n pairs of equivalent parallel samples filter-collected. The first series of tests aims to assess on real samples the equivalence between results obtained by the tested procedure with those obtained by the EMEP ions extraction and the EN 12341 standard methods, whereas the second aims to evaluate the reproducibility of analytical results of elemental determination in the leached and dissolved fractions; in the latter case data reliability is also evaluated as a function of the environment-intrinsic variability of real samples. To avoid errors due to sampling differences data from filter pairs were standardized both by gravimetric determination of loaded filters, according to the EN 12341 standard and by the rate [SO 4 2−] A/[SO 4 2−] B, where [SO 4 2−] indicate the soluble sulphate concentration in the extract; in the latter case values improved for all elements and in both fractions. Results of equivalence with standard methods and reproducibility tests are evaluated as mean relative percentage differences (Δ%) and percentage elements recoveries ( R%). The application of the validation scheme to the two-step leaching method is here discussed for non-volatile ions and for 17 elements detected on 22 pairs of low-volume collected PM 10 samples on Teflon filters.

In situ matrix evaporation by isothermal distillation of high-purity reagents for the determination of trace impurities by ion chromatography

In situ matrix evaporation of high-purity acids based on isothermal distillation was achieved in a high-density polyethylene (HDPE) container on a water bath, to avoid contamination from the laboratory environment. The solubility of water and acid vapours in glycerol due to co-association was utilized to achieve complete evaporation. All major sources which contribute to the process blank were taken care of in a simple and effective way. A 50-fold preconcentration with >99.9% matrix removal was achieved for the analysis of low-boiling acids, HCl, HF, HNO3 and H2O2. The non-volatile ions NH4+, Li+, Na+, K+, Mg2+, Ca2+, SO4(2-) and PO4(3-) were determined by ion chromatograph with conductivity detection. The detection limits were 6-130 ng/l with recoveries of 85-110% for all ions studied.

In situ matrix evaporation by isothermal distillation of high-purity reagents for the determination of trace impurities by ion chromatography

In situ matrix evaporation of high-purity acids based on isothermal distillation was achieved in a high-density polyethylene (HDPE) container on a water bath, to avoid contamination from the laboratory environment. The solubility of water and acid vapours in glycerol due to co-association was utilized to achieve complete evaporation. All major sources which contribute to the process blank were taken care of in a simple and effective way. A 50-fold preconcentration with >99.9% matrix removal was achieved for the analysis of low-boiling acids, HCl, HF, HNO 3 and H 2O 2. The non-volatile ions NH 4 +, Li +, Na +, K +, Mg 2+, Ca 2+, SO 4 2− and PO 4 3− were determined by ion chromatograph with conductivity detection. The detection limits were 6–130 ng/l with recoveries of 85–110% for all ions studied.

Vertical divergence of fogwater fluxes above a spruce forest

Two almost identical eddy covariance measurement setups were used to measure the fogwater fluxes to a forest ecosystem in the “Fichtelgebirge” mountains (Waldstein research site, 786 m a.s.l.) in Germany. During the first experiment, an intercomparison was carried out with both setups running simultaneously at the same measuring height on a meteorological tower, 12.5 m above the forest canopy. The results confirmed a close agreement of the turbulent fluxes between the two setups, and allowed to intercalibrate liquid water content (LWC) and gravitational fluxes. During the second experiment, the setups were mounted at a height of 12.5 and 3 m above the canopy, respectively. For the 22 fog events, a persistent negative flux divergence was observed with a greater downward flux at the upper level. To extrapolate the turbulent liquid water fluxes measured at height z to the canopy of height h c, a conversion factor 1/[1+0.116( z− h c)] was determined. For the fluxes of nonvolatile ions, no such correction is necessary since the net evaporation of the fog droplets appears to be the primary cause of the vertical flux divergence. Although the net evaporation reduces the liquid water flux reaching the canopy, it is not expected to change the absolute amount of ions dissolved in fogwater.

Surface application of ammonium thiosulfate fertilizer to reduce volatilization of 1,3-dichloropropene from soil

Atmospheric emission of the soil fumigant 1,3-dichloropropene (1,3-D) is of environmental concern because of its toxicity and carcinogenicity. Thiosulfate fertilizers have been found to rapidly transform 1,3-D in soil to non-volatile ions which are less toxic. We investigated the use of surface application of ammonium thiosulfate (ATS) for reducing 1,3-D volatilization. In packed soil columns, emission of 1,3-D applied by sub-surface injection decreased with increasing ATS application rate and the amount of water used for delivering ATS. When ATS was applied in 9 mm water at 64g m ˇ2 , total 1,3-D emission was reduced by 61%. The reduction was 89% when ATS was applied at 193 g m ˇ2 . Bioassays showed that ATS application did not affect the effectiveness of 1,3-D for controlling citrus nematodes. In field plots where a 1,3-D emulsified formulation was applied via sub-surface drip, surface spray of ATS reduced 1,3-D emissions by 50%, and by 71% when the surface was also covered with polyethylene film. ATS application had no effect on the efficacy of root-knot nematode control or tomato yields. These results suggest that surface application of thiosulfate fertilizers may be a feasible and effective strategy for minimizing 1,3-D emissions. # 2000 Society of Chemical Industry

Chemical methods for removing radon and radon daughters from air.

Liquid bromine trifluoride and the solid complexes ClF(2)SbF(6), BrF(2)SbF(6), BrF(4)Sb(2)F(11), IF(4)(SbF(6))(3) and BrF(2)BiF(6) react spontaneously with radon and radon daughters at 25 degrees C, converting the radioelements to nonvolatile ions and compounds. The reagents can be used in gas-scrubbing units to remove radon and radon daughters from air. The halogen fluoride-antimony pentafluoride complexes may be suitable for purifying air in uranium mines and analyzing radon in air, since they have low dissociation pressures at 25 degrees C and are less hazardous to handle than liquid halogen fluorides.