Ion-induced nucleation of pure biogenic particles.

Atmospheric aerosols and their effect on clouds are thought to be important for anthropogenic radiative forcing of the climate, yet remain poorly understood. Globally, around half of cloud condensation nuclei originate from nucleation of atmospheric vapours. It is thought that sulfuric acid is essential to initiate most particle formation in the atmosphere, and that ions have a relatively minor role. Some laboratory studies, however, have reported organic particle formation without the intentional addition of sulfuric acid, although contamination could not be excluded. Here we present evidence for the formation of aerosol particles from highly oxidized biogenic vapours in the absence of sulfuric acid in a large chamber under atmospheric conditions. The highly oxygenated molecules (HOMs) are produced by ozonolysis of α-pinene. We find that ions from Galactic cosmic rays increase the nucleation rate by one to two orders of magnitude compared with neutral nucleation. Our experimental findings are supported by quantum chemical calculations of the cluster binding energies of representative HOMs. Ion-induced nucleation of pure organic particles constitutes a potentially widespread source of aerosol particles in terrestrial environments with low sulfuric acid pollution.

Development of a thoracic personal sampler system for co-sampling of sulfuric acid mist and sulfur dioxide gas.

A novel personal sampler was designed to measure inorganic acid mists and gases for determining human exposure levels to these acids in workplaces. This sampler consists of (1) a parallel impactor for classifying aerosol by size following the ISO/CEN/ACGIH defined human thoracic fraction, (2) a cellulose filter to collect the residual acid mist but allowing penetration of sulfur dioxide gas, and (3) an accordion-shaped porous membrane denuder (aPMD) for adsorbing the penetrating sulfur dioxide gas. Acid-resistant PTFE was chosen as the housing material to minimize sampling interference. To test the performance of the parallel impactor, monodisperse aerosol was created by a vibrating orifice aerosol generator. The results showed that the penetration curve of the impactor run at 2 LPM flow rate agreed well with the defined thoracic fraction. Almost all sampling biases were within 10% for particle size distributions with MMAD between 1-25 µm and GSD between 1.75-4, which meets the criteria of the EN 13205 standard. To evaluate the performance of the aPMDs, sulfur dioxide gas was sourced directly from a cylinder. The aPMDs maintained a gas collection efficiency greater than 95% for 4 hr when sampling 8.6 ppm of sulfur dioxide gas. While the aPMD had similar performance to the commonly adopted annular or honeycomb denuders made of glass, this shatterproof aPMD is only half of the volume and 1/25th the weight of the honeycomb denuder. Testing of the entire sampler with a mixture of sulfuric acid mist and sulfur dioxide gas showed the system could sample both with negligible interference. All the test results illustrate that the new sampler, which is flat, lightweight, and portable, is suitable for personal use and is capable of a more accurate assessment of human exposure to inorganic acid mist and SO2 gas.

Assessment of nanofiltration and reverse osmosis potentialities to recover metals, sulfuric acid, and recycled water from acid gold mining effluent.

This work assessed the potential of nanofiltration (NF) and reverse osmosis (RO) to treat acid streams contaminated with metals, such as effluent from the pressure oxidation process (POX) used in refractory gold ore processing. NF and RO were evaluated in terms of rejections of sulfuric acid and metals. Regarding NF, high sulfuric acid permeation (∼100%), was observed, while metals were retained with high efficiencies (∼90%), whereas RO led to high acid rejections (<88%) when conducted in pH values higher than 1. Thus, sequential use of NF and RO was proved to be a promising treatment for sulfuric acid solutions contaminated by metals, such as POX effluent. In this context, a purified acid stream could be recovered in NF permeate, which could be further concentrated in RO. Recovered acid stream could be reused in the gold ore processing or commercialized. A metal-enriched stream could be also recovered in NF retentate and transferred to a subsequent metal recovery stage. In addition, considering the high acid rejection obtained through the proposed system, RO permeate could be used as recycling water.

[Determination of thoracic and inhalable fraction of sulfuric acid(VI) in workplace air]. / Oznaczanie frakcji torakalnej i wdychalnej kwasu siarkowego(VI) w powietrzu srodowiska pracy.

BACKGROUND: The article presents the results of the determination of the inhalable and thoracic fraction of sulfuric acid(VI) in 3 workplaces producing or processing this chemical. MATERIAL AND METHODS: To collect thoracic fractions of sulfuric acid(VI) Parallel Particle Impactor (PPI) was used. To isolate inhalable fraction of sulfuric acid(VI) from the air we used a sampler developed at the Institute of Occupational Medicine (IOM), United Kingdom. Parallel Particle Impactor and IOM samplers worked with pumps at a flow of 2 l/min. For the chromatographic determination of the inhalable and thoracic fraction of sulfuric acid(VI) in workplace the ion chromatography with conductometric detection was used. RESULTS: Depending on the sampling place the concentration of thoracic fraction of sulfuric acid(VI) was: 0.0015-0.01 mg/m3 in workplace A, 0.0019-0.25 mg/m3 in workplace B, and 0.002-0.01 mg/m3 in workplace C. Of 22 tested workstations in workplace B only 7 exceeded the threshold limit value (TLV) for the concentration of thoracic fraction of sulfuric acid(VI). CONCLUSIONS: The results confirmed the utility of PPI for sampling the thoracic fraction of sulfuric acid(VI). The studies show that at 22 workstations in the establishments producing or processing sulfuric acid(VI) thoracic fraction of acid is emitted to the work environment. The collected data showed that the thoracic fraction of sulfuric acid(VI) represents on average 64% of the inhalable fraction. Med Pr 2016;67(4):509-515.

A novel electrochemical chiral sensor for 3,4-dihydroxyphenylalanine based on the combination of single-walled carbon nanotubes, sulfuric acid and square wave voltammetry.

We demonstrate, for the first time, an electrochemical sensor that provides antipodal signals upon application of square wave voltammetry (SWV), for enantioselective recognition of 3,4-dihydroxyphenylalanine based on chiral single-walled carbon nanotubes (SWCNTs) in the presence of sulphuric acid. Interestingly, the enantioselectivity was not observed using the common method of cyclic voltammetry (CV) but the SWV peak currents of enantiomers were found to be quite different and hence the enantiomers could be successfully recognized. Moreover, the antipodal signals provided by two SWV scan modes offer the possibility for results to be confirmed mutually, showing a great practical value and analytical application prospects.

Determination of sulfuric acid concentration for anti-cavitation characteristics of Al alloy by two step anodizing process to forming nano porous.

Al alloy is a highly active metal but forms a protective oxide film having high corrosion resistance in atmosphere environment. However, the oxide film is not suitable for practical use, since the thickness of the film is not uniform and it is severly altered with formation conditions. This study focused on developing an aluminum anodizing layer having hardness, corrosion resistance and abrasion resistance equivalent to a commercial grade protective layer. Aluminum anodizing layer was produced by two-step aluminum anodizing oxide (AAO) process with different sulfuric acid concentrations, and the cavitation characteristics of the anodized coating layer was investigated. In hardness measurement, the anodized coating layer produced with 15 vol.% of sulfuric acid condition had the highest value of hardness but exhibited poor cavitation resistance due to being more brittle than those with other conditions. The 10 vol.% of sulfuric acid condition was thus considered to be the optimum condition as it had the lowest weight loss and damage depth.

Technical note: Evaluation of markers for estimating duodenal digesta flow and ruminal digestibility: Acid detergent fiber, sulfuric acid detergent lignin, and n-alkanes.

The amount of digesta flowing to the duodenum is a relevant measurement for the evaluation of nutrient supply to ruminants, which is usually estimated in animals fitted with a duodenal T-type cannula using internal or external markers. This study evaluated acid detergent fiber (ADF) compared with external (C32n-alkane) and internal [sulfuric acid lignin (ADL) and n-alkanes C31 and C33] markers for estimating duodenal flow and(or) ruminal digestibility of dry matter (DM) in cattle and sheep. In the first assay, 4 duodenally cannulated Holstein steers housed in metabolism cages, dosed with C32n-alkane, and fed Avena strigosa plus concentrate and increasing levels of tannin extract to reduce ruminal digestibility, were used in a Latin square design. The mobile-bag technique was used to measure the intestinal disappearance of ADL and ADF from forage (Avena strigosa, Pennisetum purpureum, Cynodon dactylon, and Medicago sativa) and concentrate (corn grain, soybean meal, and sunflower meal) samples that were previously incubated in the rumen of additional fistulated steer for 12, 24, 36, or 48 h. The ADF concentration in residues recovered in the feces was strongly related to the ADF concentration in residues at the duodenum (R(2)=0.93, standard deviation=30.0, n=901). This relationship showed a lower precision for ADL fraction (R(2)=0.88, standard deviation=12.6, n=590). In a second assay, duodenal flow and ruminal DM digestibility were calculated from the duodenal and fecal concentration of either marker. We observed a significant effect of marker type on ruminal DM digestibility values, and the effect of tannin treatments was observed only when ADF or ADL was used as the marker. The lowest residual error was obtained for ADF. Ruminal DM digestibility was, on average, higher for C31 and C(33)n-alkanes, and the use of dosed C(32)n-alkane resulted in a negative value. In the third assay, a data set of 235 individual observations was compiled from digestibility trials to compare ADF and ADL as markers for estimating duodenal digesta flow in wethers (n=204) and cattle (n=31). We observed a strong relationship between markers (R(2)=0.84 in sheep and R(2)=0.88 in cattle), but variance analysis within trials indicated that ADF was more precise than ADL. In conclusion, in digestibility trials in which fecal output was measured and spot samples of the duodenal digesta were obtained, duodenal flow and ruminal digestibility of the DM may be estimated from the relationship between the ADF concentration in feces and that in the duodenal digesta of ruminants.

Assessment of exposure to sulfuric acid in workers using cleaning equipment operated with lead-acid batteries.

Sulfuric acid, a constituent of lead-acid batteries, is an extremely hazardous substance, necessitating utmost caution. Unfortunately, many workers that utilize battery-operated equipment remain unaware of the potential exposure. This study aims to evaluate the potential exposure to sulfuric acid among workers employed by small companies associated with the operation of floor cleaning equipment powered by lead-acid batteries. Only cleaning equipment (hand-push and ride-on types) that required supplementation of lead-acid batteries with distilled water were targeted. Exposure measurement and analysis were performed according to the guidelines of NIOSH and including personal sampling and stationary sampling on the equipment. Exposure measurements indicated that workers were exposed to sulfuric acid. Additionally, the concentration level was slightly elevated in the stationary samples compared to personal samples. This study affirms that workers can experience exposure to sulfuric acid, even in the absence of direct handling of the substance. Consequently, there is a need to recognize and mitigate the potential risks.

High-performance organic nanomembrane based sensors for rapid in situ acid detection.

Here, we demonstrate the fabrication, characterization, and tailoring of porous organic nanomembranes and their direct integration on inorganic substrates for sensing applications. The chemically prepared nanomembranes can be integrated on both conducting and insulating substrates by either transfer or direct synthesis. We also successfully demonstrate their use for the detection of commonly used acids including HCl, H(2)SO(4), or H(3)PO(4) and their respective counterions, chlorides, sulfates, and phosphates. Impressively, the in situ acid detection is achieved down to 5 nmol·L(-1), while the quantification is feasible between 5 µmol·L(-1) and 10 mmol·L(-1). These values are among the lowest values reported so far in literature. Furthermore, the organic nanomembrane based sensor covers a wide concentration range of almost 8 orders of magnitude including the environmental limits currently adopted.

A BODIPY derivative as a highly selective "Off-On" fluorescent chemosensor for hydrogen sulfate anion.

A new fluorescent receptor for 1 anions has been synthesized by the combination of BODIPY dye and indole moiety. The binding and sensing abilities of receptor 1 toward various anions have been studied by absorption, emission and (1)H NMR titrations spectroscopies. Receptor 1 could act as a highly selective "Off-On" fluorescent sensor for hydrogen sulfate anion in CH(3)CN solvent and CH(3)CN-H(2)O medium. The fluorescence response of receptor 1 toward HSO(4)(-) in CH(3)CN solvent could be due to the suppressed PET (photo-induced electron transfer) process induced by the multiple hydrogen bonding interactions between receptor 1 and HSO(4)(-). In CH(3)CN-H(2)O medium, the HSO(4)(-)-induced change is mainly the consequence of a simple protonation of the CH=N- moiety of receptor 1, which inhibited the PET process and "turned on" the fluorescence of 1.

First online measurements of sulfuric acid gas in modern heavy-duty diesel engine exhaust: implications for nanoparticle formation.

To mitigate the diesel particle pollution problem, diesel vehicles are fitted with modern exhaust after-treatment systems (ATS), which efficiently remove engine-generated primary particles (soot and ash) and gaseous hydrocarbons. Unfortunately, ATS can promote formation of low-vapor-pressure gases, which may undergo nucleation and condensation leading to formation of nucleation particles (NUP). The chemical nature and formation mechanism of these particles are only poorly explored. Using a novel mass spectrometric method, online measurements of low-vapor-pressure gases were performed for exhaust of a modern heavy-duty diesel engine operated with modern ATS and combusting low and ultralow sulfur fuels and also biofuel. It was observed that the gaseous sulfuric acid (GSA) concentration varied strongly, although engine operation was stable. However, the exhaust GSA was observed to be affected by fuel sulfur level, exhaust after-treatment, and driving conditions. Significant GSA concentrations were measured also when biofuel was used, indicating that GSA can be originated also from lubricant oil sulfur. Furthermore, accompanying NUP measurements and NUP model simulations were performed. We found that the exhaust GSA promotes NUP formation, but also organic (acidic) precursor gases can have a role. The model results indicate that that the measured GSA concentration alone is not high enough to grow the particles to the detected sizes.

Quantitative assessment of the sulfuric acid contribution to new particle growth.

The Nano Aerosol Mass Spectrometer (NAMS) was deployed to rural/coastal and urban sites to measure the composition of 20-25 nm diameter nanoparticles during new particle formation (NPF). NAMS provides a quantitative measure of the elemental composition of individual, size-selected nanoparticles. In both environments, particles analyzed during NPF were found to be enhanced in elements associated with inorganic species (nitrogen, sulfur) relative to that associated with organic species (carbon). A molecular apportionment algorithm was applied to the elemental data in order to place the elemental composition into a molecular context. These measurements show that sulfate constitutes a substantial fraction of total particle mass in both environments. The contribution of sulfuric acid to new particle growth was quantitatively determined and the gas-phase sulfuric acid concentration required to incorporate the measured sulfate fraction was calculated. The calculated values were compared to those calculated by a sulfuric acid proxy that considers solar radiation and SO(2) levels. The two values agree within experimental uncertainty. Sulfate accounts for 29-46% of the total mass growth of particles. Other species contributing to growth include ammonium, nitrate, and organics. For each location, the relative amounts of these species do not change significantly with growth rate. However, for the coastal location, sulfate contribution increases with increasing temperature whereas nitrate contribution decreases with increasing temperature.

Sulfuric acid at workplaces--applicability of the new Indicative Occupational Exposure Limit Value (IOELV) to thoracic particles.

Until 2009, the limit values for airborne sulfuric acid in Europe were based on the inhalable particle fraction (e.g. MAK (Maximum allowed concentration at workplace) value 0.1 mg m(-3) as the inhalable fraction). With the publication of the Commission Directive 2009/161/EU, an Indicative Occupational Exposure Limit Value (IOELV) of 0.05 mg m(-3) for sulfuric acid aerosols was based for the first time on the thoracic particle fraction. To permit a comparison of the measured values for the inhalable fraction with those of the thoracic fraction and to quantify the thoracic fraction, a cyclone was fabricated out of sulfuric-acid-resistant stainless steel that achieves suitable collection characteristics (PM(10)) at a flow rate of 5.34 L min(-1). 49 measurements were carried out in parallel in 21 companies. At concentrations well below the IOELV, there is little difference between the thoracic and inhalable particle concentrations. At higher concentrations (>0.1 mg m(-3) inhalable aerosol), larger droplets have a marked effect on the measured values and the thoracic fraction accounts for only 32.1 ± 12.5% of the inhalable fraction. The EU's IOELV and the proposal of the MAK Commission therefore provide a comparable level of protection. In the transposition of the IOELV into national law, an air limit of 0.1 mg m(-3) could therefore be implemented for the inhalable fraction.

Particle number size distribution and new particle formation: new characteristics during the special pollution control period in Beijing.

New particle formation is a key process in shaping the size distribution of aerosols in the atmosphere. We present here the measurement results of number and size distribution of aerosol particles (10-10000 nm in diameter) obtained in the summer of 2008, at a suburban site in Beijing, China. We firstly reported the pollution level, particle number size distribution, diurnal variation of the particle number size distribution and then introduced the characteristics of the particle formation processes. The results showed that the number concentration of ultrafine particles was much lower than the values measured in other urban or suburban areas in previous studies. Sharp increases of ultrafine particle count were frequently observed at noon. An examination of the diurnal pattern suggested that the burst of ultrafine particles was mainly due to new particle formation promoted by photochemical processes. In addition, high relative humidity was a key factor driving the growth of the particles in the afternoon. During the 2-month observations, new particle formation from homogeneous nucleation was observed for 42.7% of the study period. The average growth rate of newly formed particles was 3.2 nm/hr, and varied from 1.2 to 8.0 nm/hr. The required concentration of condensable vapor was 4.4 x 10(7) cm(-3), and its source rate was 1.2 x 106 cm(-3) sec(-1). Further calculation on the source rate of sulphuric acid vapor indicated that the average participation of sulphuric acid to particle growth rates was 28.7%.

Research Progress of Graphene and Its Derivatives towards Exhaled Breath Analysis.

The metabolic process of the human body produces a large number of gaseous biomarkers. The tracking and monitoring of certain diseases can be achieved through the detection of these markers. Due to the superior specific surface area, large functional groups, good optical transparency, conductivity and interlayer spacing, graphene, and its derivatives are widely used in gas sensing. Herein, the development of graphene and its derivatives in gas-phase biomarker detection was reviewed in terms of the detection principle and the latest detection methods and applications in several common gases, etc. Finally, we summarized the commonly used materials, preparation methods, response mechanisms for NO, NH3, H2S, and volatile organic gas VOCs, and other gas detection, and proposed the challenges and prospective applications in this field.

Depression of ammonia uptake to sulfuric acid aerosols by competing uptake of ambient organic gases.

The neutralization of acidic aerosols by ammonia has been studied through experiments which combine ambient air with laboratory generated sulfuric acid aerosol. Results indicated that acidic aerosol mixed with organic free air and ammonia was neutralized on a time scale<1 min, consistent with expectations. However, in the presence of ambient organic gases and ammonia, the rate of aerosol neutralization is significantly reduced. This reduction in ammonia uptake was concurrent with an increase in the amount of particle phase organics. A steady state in the NH4+/SO4(2-) in the presence of organic gases was established on time scales of 10 min to several hours, corresponding to NH3 uptake coefficients in the range of 4×10(-3)-2×10(-4). The degree to which neutralization was slowed was dependent upon the initial ammonia concentration and the organic mass added to the aerosols. These results suggest that inorganic equilibrium thermodynamic models may overestimate the rate of ammonia uptake and that ambient particles may remain acidic for longer than previously expected.

Variability in morphology, hygroscopicity, and optical properties of soot aerosols during atmospheric processing.

The atmospheric effects of soot aerosols include interference with radiative transfer, visibility impairment, and alteration of cloud formation and are highly sensitive to the manner by which soot is internally mixed with other aerosol constituents. We present experimental studies to show that soot particles acquire a large mass fraction of sulfuric acid during atmospheric aging, considerably altering their properties. Soot particles exposed to subsaturated sulfuric acid vapor exhibit a marked change in morphology, characterized by a decreased mobility-based diameter but an increased fractal dimension and effective density. These particles experience large hygroscopic size and mass growth at subsaturated conditions (<90% relative humidity) and act efficiently as cloud-condensation nuclei. Coating with sulfuric acid and subsequent hygroscopic growth enhance the optical properties of soot aerosols, increasing scattering by approximately 10-fold and absorption by nearly 2-fold at 80% relative humidity relative to fresh particles. In addition, condensation of sulfuric acid is shown to occur at a similar rate on ambient aerosols of various types of a given mobility size, regardless of their chemical compositions and microphysical structures. Representing an important mechanism of atmospheric aging, internal mixing of soot with sulfuric acid has profound implications on visibility, human health, and direct and indirect climate forcing.

Interaction of acid mine drainage with Ordinary Portland Cement blended solid residues generated from active treatment of acid mine drainage with coal fly ash.

Fly ash (FA) has been investigated as a possible treatment agent for Acid mine drainage (AMD) and established to be an alternative, cheap and economically viable agent compared to the conventional alkaline agents. However, this treatment option also leads to generation of solid residues (SR) that require disposal and one of the proposed disposal method is a backfill in coal mine voids. In this study, the interaction of the SR with AMD that is likely to be present in such backfill scenario was simulated by draining columns packed with SR and SR + 6% Ordinary Portland Cement (OPC) unsaturated with simulated AMD over a 6 month period. The evolving geochemistry of the liquid/solid (L/S) system was evaluated in-terms of the mineral phases likely or controlling contaminants attenuation at the different pH regimes generated. Stepwise acidification of the percolates was observed as the drainage progressed. Two pH buffer zones were observed (7.5-9 and 3-4) for SR and (11.2-11.3 and 3.5-4) for SR + 6% OPC. The solid residue cores (SR) appeared to have a significant buffering capacity, maintaining a neutral to slightly alkaline pH in the leachates for an extended period of time (97 days: L/S 4.3) while SR + 6% OPC reduced this neutralization capacity to 22 days (L/S 1.9). Interaction of AMD with SR or SR + 6% OPC generated alkaline conditions that favored precipitation of Fe, Al, Mn-(oxy) hydroxides, Fe and Ca-Al hydroxysulphates that greatly contributed to the contaminants removal. However, precipitation of these phases was restricted to the pH of the leachates remaining at neutral to circum-neutral levels. Backfill of mine voids with SR promises to be a feasible technology for the disposal of the SR but its success will greatly depend on the disposal scenario, AMD generated and the alkalinity generating potential of the SR. A disadvantage would be the possible re-dissolution of the precipitated phases at pH < 4 that would release the contaminants back to the water column. However extrapolation of this concept to a field scenario can greatly enhance beneficial application of fly ash (FA) and solid residues (SR) generated from treatment of AMD.

Validation of a phenol-sulfuric acid method in a microplate format for the quantification of soluble sugars in ruminant feeds.

Soluble sugars in feeds are important for ruminant production; however, performing numerous sugar analyses within a short period is a laborious task. Here, we developed a phenol-sulfuric acid (PSA) assay in a microplate format to quantify soluble sugars in ruminant feeds. This method is easy and quick and requires only a small quantity of harmful reagents. We found that assay measurements were not affected by the representative organic acids and sugar alcohol contained in feeds. The treatment of activated charcoal with ethanol extract prior to the PSA assay was effective in removing interfering compounds for a more accurate determination of soluble sugars in certain feeds. Furthermore, the inter-day and intra-day repeatability of the present method was acceptable. Hence, we conclude that the method developed in this study is suitable for routine analysis of soluble sugars content in ruminant feeds.

Dental erosion in workers exposed to sulfuric acid in lead storage battery manufacturing facility.

Dental erosion, and specifically its symptoms, has long been studied in Japan as an occupational dental disease. However, in recent years, few studies have investigated the development of this disease or labor hygiene management aimed at its prevention. As a result, interest in dental erosion is comparatively low, even among dental professionals. Our investigation at a lead storage battery factory in 1991 found that the work environmental sulfuric acid density was above the tolerable range (1.0mg/m(3)) and that longterm workers had dental erosion. Therefore, workers handling sulfuric acid were given an oral examination and rates of dental erosion by tooth type, rates of erosion by number of working years and rates of erosion by sulfuric acid density in the work environment investigated. Where dental erosion was diagnosed, degree of erosion was identified according to a diagnostic criterion. No development of dental erosion was detected in the maxillary teeth, and erosion was concentrated in the anterior mandibular teeth. Its prevalence was as high as 20%. Rates of dental erosion rose precipitously after 10 working years. The percentages of workers with dental erosion were 42.9% for 10-14 years, 57.1% for 15-19 years and 66.7% for over 20 years with 22.5% for total number of workers. The percentages of workers with dental erosion rose in proportion to work environmental sulfuric acid density: 17.9% at 0.5-1.0, 25.0% at 1.0-4.0 and 50.0% at 4.0-8.0mg/m(3). This suggests that it is necessary to evaluate not only years of exposure to sulfuric acid but also sulfuric acid density in the air in factory workers.