Sorbent Samples Research Articles

The use of a hypromellose based sorbent for a solid-phase extraction in the quantitative determination of procaine in combination drugs

Aim – to assess the selectivity and metrological characteristics of the spectrophotometric method for procaine determination in combination drugs using a solid-phase extraction sorbent based on hypromellose. Material and methods. The solid-phase extraction sorbent was obtained with hypromellose and ethyl cyanoacrylate; the procaine hydrochloride and sodium hydroxide formed the active centers. The sorbent was prepared using a standard method. The sorption capacity of the obtained sorbent samples for procaine was 10.2 ± 1.0 µg/g. For the study, we selected the combination drugs containing procaine and its salts, such as "Menovazin", "Sulfocamphocaine", and "Otolorin". The eluate optical density was registered using a SF-56 spectrophotometer (OKB SPECTR LLC) at an analytical wavelength of 292 nm in a cuvette with an optical layer thickness of 1 cm. The reference solution was a 0.1 M hydrochloric acid solution. To calculate the procaine content in the eluates, a calibration graph (dependence of eluate optical density on procaine concentration) was plotted in the concentration range of 1–20 mcg/ml. To evaluate the selectivity (specificity) of sample preparation in chromatographic separation of the combination drugs, the absorption spectra were registered in the wavelength range of 200–400 nm for eluates obtained using purified water and a 0.1 M hydrochloric acid solution. The procaine and benzocaine were identified in the eluate by the presence of absorption maxima at wavelengths of 222 and 286 nm for benzocaine, and 228 and 292 nm for procaine. For statistical processing of the experimental results and determination of metrological characteristics of the analysis method, we followed the GPM.1.1.0013 "Statistical processing of results of physical, physicochemical, and chemical tests". Results. We have demonstrated the selectivity of the spectrophotometric determination of procaine in certain combination drugs using a solid-phase extraction sorbent based on hypromellose. The selective binding of the analyzed substance with active centers in the sorbent and stepwise elution with purified water and a 0.1 M hydrochloric acid solution during solid-phase extraction eliminated the interfering effect of drug components during the UV-spectrophotometry of procaine. The use of a hypromellose based sorbent improved the metrological characteristics and reduced the systematic error of the quantitative determination method by an average of 14.4%. The proposed methodological approach using a selective sorbent might be recommended as the quality control for combination drugs containing procaine and its salts.

The Representativeness of Subslab Soil Gas Collection as Effected by Probe Construction and Sampling Methods

AbstractSubslab soil gas (SSSG) samples were collected as part of an investigation to evaluate vapor intrusion (VI) into a building. The June 2015 Office of Solid Waste and Emergency Response (OSWER) VI Guide (U.S. Environmental Protection Agency [U.S. EPA] 2015) does not provide specific, detailed recommendations regarding how to collect SSSG samples. The data collected in this study will be used to provide input into future OSWER VI Guidance documents on SSSG sample collection. To this end, three different types of subslab sampling ports were constructed with various sampling techniques within a hexagon‐shaped grid in near proximity to each other. Conventional‐, Vapor Pin‐, and California‐style ports were established in duplicate for continual analysis by onsite gas chromatography‐electron capture detection (GC‐ECD). Triplicate ports were established to evaluate active and passive long‐term sampling methods to determine short range temporal differences. Active sampling methods included evacuated stainless‐steel canisters fitted with capillary flow controllers (Modified U.S. EPA Method TO‐15 [U.S. EPA 1999a]) and sorbent tubes collected using a syringe (Modified EPA TO‐17 [U.S. EPA 1999b]). The Passive sampling method used was sorbent tube samples collected following the EPA TO‐17 sampling method (Modified). This study did not identify any systematic differences in sample results between conventional, Vapor Pin, and CA‐style probes for used in SSSG sampling. The decisions for site management would probably be the same for data from any subslab port style, active or passive sampling techniques over durations less than 2 weeks.

INFLUENCE OF HEATING CONDITIONS ON TEXTURE PARAMETERS AND ADSORPTION PROPERTIES OF APRICOT KERN SHELL CARBONIZATES

Some results of a comparative analysis of the textural parameters and sorption characteristics of carbonizates obtained by microwave and traditional heating of apricot kernel shells are presented. It has been shown that sorbent samples obtained by microwave carbonization of shells, in comparison with sorbents obtained by traditional heating, are characterized by a more uniform distribution of pore sizes, greater adsorption capacity and low fractal dimension of the surface.

Influence of Thermal and Chemical Treatment on Biosorbent from Rice Husk and Its Application in Removal of Resorcinol from Industrial Wastewater

The removal of phenolic compounds is of great importance because of their toxic nature and potentially harmful effects on the environment and human health. This study examines the use of rice husk as a biosorbent for eliminating phenolic compounds, particularly resorcinol, from industrial wastewater. Three types of rice husk, namely raw rice husk (RRH), chemically treated rice husk (CTRH), and thermally treated rice husk (TTRH), are utilized after grinding and methanol treatment. Characterization techniques including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and optical microscopy are used to analyze the rice husk-based adsorbents. The microscopic analysis reveals the presence of nano-pores in TTRH and the existence of carbonyl and hydroxyl groups in all sorbent samples. XRD analysis confirms the presence of silica in biosorbents. This study also examines the influence of dosage and initial concentration on resorcinol sorption. Optimized dosages of 0.5 g (RRH), 0.5 g (CTRH), and 1.5 g (TTRH) result in sorption capacities of 14 mg/g (RRH), 11 mg/g (CTRH), and 5 mg/g (TTRH). Isotherm analysis indicates that the Langmuir isotherm best describes the sorption behavior of TTRH, while the Freundlich isotherm is observed for CTRH, and both RRH and CTRH follow the Temkin isotherm.

VALIDATION OF THE STANDARD CERTIFIED METHOD FOR THE DETERMINATION OF PETROLEUM PRODUCTS IN SORBENT SAMPLES

The validation of a standard certified method for measuring the mass fraction of oil products in soils and bottom sediments by IR spectrometry for measuring the content of oil products in sorbent samples based on ash and slag waste from thermal power engineering, and changes in the method of sample preparation in order to improve the metrological characteristics of the method are proposed. To calculate the metrological characteristics of the method to be validated, 48 measurements were carried out according to the recommendations set out in RMG 61-2010 (Appendix E). The assessment of the repeatability index was carried out according to the Cochran criterion. Grubbs statistics were used to evaluate the intralaboratory precision index. The correctness score was determined using a two-sample Student’s t-test. The assessment of the accuracy indicator was performed by the selective relative standard deviation of the measurement results of the control sample. Quality indicators of the standard methodology PND F 16.1:2.2.22-98 (2005 edition): repeatability rate 8 %; index of intralaboratory precision 10 %; correctness score 15 %; accuracy rate 25 %. Quality indicators of the method being validated: repeatability rate 2.7 %; index of intralaboratory precision 2.7 %; correctness score 1.3 %; accuracy rate 5.3 %. The measurement results obtained using the developed validated method for measuring the oil product content in the samples of modified sorbent based on ash and slag wastes are more reproducible in terms of repeatability and precision, as well as more correct and accurate in comparison with the results obtained when measuring using the standard PND F method 16.1:2.2.22-98 (2005 edition).

Evaluation of Ca-Based Sorbents for Gaseous HCl Emissions Adsorption

The problem of acid gas exhaust emissions treatment has not been fully resolved at present. Dry adsorption of acid gases with alkaline sorbents is currently being investigated, to improve solid sorbents. In this study, 5 types of hydrated lime were characterised and tested. The sorption capacities were measured by means of a system consisting of a feed line (HCl/N2), a thermostatic reactor and a water absorber. The physical characteristics of sorbent samples were also compared. Analyses conducted with scanning electronic microscopy revealed that sample C1 showed uniform particle distribution. Samples C2 and C3 showed the co-presence of fine and coarse particles. Sample C4 showed very fine particles with agglomeration phenomena. In sample C5, fibrous elements were found. Energy dispersive spectrometry (EDS) analyses showed a similar composition of the samples, with the exception of the presence of Mg in some of them. After 30 min of testing, the following differences in sorption capacities with respect to C1 (3.59 mg g−1) were found: C2, −20%; C3, −13%; C4, −17%; C5, −3%. Higher sorption capacities were associated with more uniform particle size distributions. Conversely, agglomeration of fine particles may have adversely affected the performance of sorbents.

Preparation of sorbents for solid-phase extraction of benzoic acid from aqueous solutions

Aim to obtain sorbents based on ethylcellulose for solid-phase extraction of benzoic acid from aqueous solutions.
 Material and methods. To create the sorbents for solid-phase extraction, we used the following reagents: ethyl cellulose, copper sulfate pentahydrate, sodium hydroxide, benzoic acid, purified water, ethyl alcohol 95%. The samples of ethyl cellulose-based sorbents were studied by Fourier transform IR spectrometry on an Agilent Cary 630 FTIR spectrometer. The Agilent Microlab PC Expert software was used for registration and primary processing of IR spectra, and for statistical analysis. The capacity of sorbents for solid-phase extraction was evaluated in a dynamic mode. The microstructure of the samples was studied by field emission scanning electron microscopy (FE-SEM) on a Hitachi SU8000 electron microscope. The specific surface area of the synthesized sorbents was measured by low-temperature nitrogen porometry using the Brunauer Emmett Teller approximation, on the Autosorb 1 device, using the Quantachrome AS1Win software, according to a well-known technique.
 Results. А method was proposed for obtaining a sorbent for solid-phase extraction of benzoic acid from aqueous solutions. The IR-spectrometry did not reveal significant differences between ethylcellulose samples and the obtained sorbent samples. The optimal concentrations of ethylcellulose and benzoic acid in the reaction mixture were determined to create a sorbent with a maximum capacity of 19.2 g/g. The differences in the morphological structure of the surface of ethylcellulose matrix and obtained sorbents were described. The specific surface area of ethylcellulose sorbent with a maximum capacity for benzoic acid was 14.10 cm2/g.

Solvent-free mechanochemical synthesis of TiO2-ethyl cellulose biocomposite for adsorption of tetracycline and organic dyes

In the study, polymeric-metal oxide hybrid composite was synthesized by mechanochemical method in ball-mill by adding different amounts of TiO2 to ethyl cellulose (EC) and its potential in tetracycline (TC) removal from aqueous solutions was investigated. In order to investigate the adsorption capacity, isotherm, kinetic and thermodynamic parameters of the adsorption process, the amount of adsorbent, contact time, solution pH, temperature effect, inert electrolyte effect and different water environment effects were experimentally carried out in batch adsorption experiments. The adsorption capacity of all sorbents was conformed according to the Freundlich isotherm model and the maximum capacity is found for 80%TiO2@EC with 23.26 mg g−1. The system reached equilibrium with 89% TC removal in 480 min and complied with the pseudo second order kinetic model. In the pH effect experiments, maximum TC removal found in pH:6. Thermodynamic parameters indicate that TC adsorption on 80%TiO2@EC is endothermic and spontaneous. Different water medium and inert electrolyte effect were found compatible with each other. Also, a decrease was observed in the specific TC removal in the presence of any ions in the system. The removal of methylene blue (MB) and malachite green (MG) azo dyes as another organic environmental pollutant was also studied and their adsorption capacities were found as 105.7 mg g−1 and 109.9 mg g−1, respectively. XRD, FTIR and SEM analyzes were performed to explain the interaction mechanism between sorbent samples and TC.

137Cs, 85Sr and 60Co sorption from model solutions of low activity liquid radioactive waste by modified oil shale

The results of the study of cesium, strontium, cobalt radionuclides sorption from model solutions simulating liquid radioactive waste on promising sorbents based on thermally modified oil shale are presented. The dependency of texture parameters obtained from the results of nitrogen adsorption-desorption on the treatment method of oil shale and their relationship to sorption parameters such as distribution coefficient and removal efficiency was discussed. Understanding how pore characteristics affect the sorption activity of such complex systems as sorbents is important for the creation of radionuclide sorption materials with improved characteristics. The efficiency of sorption of cesium, strontium and cobalt radionuclides was rather high for sorbent samples: the distribution coefficient was about 103–104 ml/g with a removal efficiency of more than 66 %. The most effective sorbent was obtained from oil shale with a heating rate of 5 deg/min without subsequent steam treatment, which is recommended to be used for low-active radioactive waste treatment.

Antibacterial and Antimycotic Properties of Modified Carbon Sorbents

The aim of the work was to study the biological activity of modifiers and carbon sorbent samples modified by them in relation to some types of microorganisms.Material and methods. The carbon sorbent under study and the modified samples were obtained at the Center of New Chemical Technologies BIC. Glycolic acid, lactic acid, glycine, and glutamic acid were used as modifiers. Strains of Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumoniae 418, Esherichia coli ATCC 25922, Candida albicans (clinical strain) were used as test cultures. The test sample was placed in the wells of a sterile plate, then a working suspension of the test culture was added in the amount of 2.0 ml until completely wet 1:1. The survival of microorganisms was determined by quantitative inoculation from each well of the «sample — microorganism» mixture on Petri dishes with simple nutrient agar using the sector crop method (Gold). The culture species were confirmed by studying their cultural, morphological, and biochemical properties.Results. The conducted studies have demonstrated high antibacterial and antimycotic activity of carbon sorbent samples modified with hydroxyl acids in relation to the most common opportunistic pathogens of pyoinflammatory diseases of bacterial and fungal nature in comparison with the initial sorbent sample. The carbon sorbent modified with lactic acid oligomer showed the highest antibacterial and antimycotic activity.Conclusion. High antibacterial and antimycotic activity of carbon sorbent samples modified with hydroxy acids and amino acids in relation to the most common opportunistic pathogens of pyoinflammatory diseases of bacterial and fungal nature was established in comparison with the initial sample of the sorbent. The carbon sorbent sample modified with amino acids has a pronounced antibacterial effect against all studied bacterial test strains, but exhibits weak antimycotic properties. The use of modified carbon sorbents is a promising direction for the application therapy of pyoinflammatory infections.

Fabrication of porous Li4SiO4 ceramic sorbent pebbles with high CO2 sorption capacity via the simple freeze-drying method

At present, the Li4SiO4 ceramic sorbents have displayed a great prospect for CO2 gas removal in the atmosphere owing to their high sorption capacity and stable sorption-desorption property. In this paper, a simple method combining the wet method and freeze-drying method is initially employed to fabricate Li4SiO4 sorbent with rich porosity and direction arrangement channels, which overcomes the dense interior structure, barren porosity, inferior adsorption stability, and costly production described in the previous literature. The effects of freeze way and temperature on the interior structure of Li4SiO4 sorbent were studied respectively. In the freeze-drying process, only the freeze-drying Li4SiO4 cylinder (FSC) green sorbents have columnar ice crystals in the interior owing to the temperature gradient, and the unidirectional alignment of pore channels can be obtained after the vacuum drying process due to the sublimation of ice crystals, which will improve CO2 capture capacity. Moreover, it can be seen from the optical image that the sorbent pebbles have a uniform distribution of diameter and sorbent samples of OSF (fabricated without the freezing process), FSP (fabricated with the freezing process), and FSC show excellent mechanical strength of 37.5 N, 22.5 N, and 0.43Mpa, respectively. Compared with OSP and FSP samples, the FSC sorbent performed superior CO2 sorption capacities (0.305 g CO2/g sorbent) and outstanding stability after 40 times cycles due to its optimal pore microstructure. Therefore, the prominent capture capacity and the satisfying crushing load of the FSC sorbents fabricated via the Freeze-drying method in this paper have promising prospects for CO2 removal.

Development of Volatility Distributions for Organic Matter in Biomass Burning Emissions.

The volatility distribution of organic emissions from biomass burning and other combustion sources can determine their atmospheric evolution due to partitioning/aging. The gap between measurements and models predicting secondary organic aerosol has been partially attributed to the absence of semi- and intermediate volatility organic compounds (S/I-VOC) in models and measurements. However, S/I-VOCs emitted from these sources and typically quantified using the volatility basis framework (VBS) are not well understood. For example, the amount and composition of S/I-VOCs and their variability across different biomass burning sources such as residential woodstoves, open field burns, and laboratory simulated open burning are uncertain. To address this, a novel filter-in-tube sorbent tube sampling method collected S/I-VOC samples from biomass burning experiments for a range of fuels and combustion conditions. Filter-in-tube samples were analyzed using thermal desorption-gas chromatography-mass spectrometry (TD/GC/MS) for compounds across a wide range of volatilities (saturation concentrations; -2 ≤ logC* ≤ 6). The S/I-VOC measurements were used to calculate volatility distributions for each emissions source. The distributions were broadly consistent across the sources with IVOCs accounting for 75% - 90% of the total captured organic matter, while SVOCs and LVOCs were responsible for 6% - 13% and 1% - 12%, respectively. The distributions and predicted partitioning were generally consistent with literature. Particulate matter emission factors spanned two orders of magnitude across the sources. This work highlights the potential of inferring gas-particle partitioning behavior of biomass burning emissions using filter-in-tube sorbent samples analyzed offline. This simplifies both sampling and analysis of S/I-VOCs for studies focused on capturing the full range of organics emitted.

Mesoporous silica nanocatalyst used in the preparation of the retention substance bentonite-sorbents sorption of isotherms research

In this study, the retention substance bentonite was used in the preparation of a mesoporous silica nanocatalyst. The analysis of sorbents from the sorption isotherm study and the results obtained were summarized. Also discussed are the chemical composition of bentonite from the Navbahor deposit, the types of sorbent isotherms obtained by the adsorption of various gases on sorbents, descriptions of sorbent isotherms in mesoporous sorbents, the phase composition of sorbent samples synthesized from textures, and the physic-chemical characteristics of the X-ray diffractometric catalyst, and the dependence of the characteristics of texturs of the characteristics of nanocomposite sorbents made from bentonite.

Application of silica-based sorbents to extraction of rare earth elements from loparite processing products

Apatite and loparite are the main sources of rare earth elements (REE) in Russia. Loparite is a complex titanate and niobate containing up to 30% wt. of REE oxides predominantly of the cerium group. Extraction processing methods are used at the stages of group separation and separation of REE concentrates. Tributyl phosphate (TBP) is a widely used extracting agent for these purposes. Extraction technologies have a number of disadvantages, in particular, a large number of separation stages because of low separation coefficients of individual REE combined with difficulties in separating liquid phases. The use of TBP-containing sorbents allows to eliminate the latter disadvantage. Both organic polymers and inorganic compounds may be used as sorbent carriers; among inorganic ones, silica is widely used, and it was selected for this study. The purpose of this work was to study the effect of variations of the proposed methods for synthesis of silica and modified TBP based sorbents on their ability to extract REE from the solutions of loparite concentrate processing. The article briefly describes a procedure for sorbent samples synthesis. Tetraethoxysilane, tributyl phosphate, stannic chloride and nanotubes have been used as starting reagents for the synthesis. A number of physicochemical properties have been determined for the synthesized samples (pore volume and their average diameter, surface area and morphology, acid-base properties of the surface), and thermogravimetric analysis has been performed. The sorption properties of the samples have been tested by the example of REE extraction from process solutions of loparite working up. The separation coefficients of Sm/La pairs up to 3.7, Pr/Nd up to 1.8 were obtained; therefore, the studied samples may be potentially used for samarium isolation from the REE combination, as well as for Pr – Nd pair separation. This study was supported by the Tomsk State University Development Programme (Priority-2030).The SEM researches and results of measuring the specific surface area (SBET) and porous structure were carried out with the equipment of Tomsk Regional Core Shared Research Facilities Center of National Research Tomsk State University. Center was supported by the Ministry of Science and Higher Education of the Russian Federation Grant no. 075-15-2021-693 (no. 13.RFC.21.0012)).

Structural, magnetic and adsorptive properties of nano spinel of cobalt aluminate doped with nickel for Cr(VI) removal

Nanocrystallines of cobalt aluminate spinel doped with Nickel (MAl2O4; M = Co+2, Ni+2) were synthesized by sol-gel method. The MAl2O4 samples were prepared by using aluminum nitrate; cobalt nitrate, nickel nitrate, citric acid and diethylene glycol mono ethyl ether as precursor materials. The nanocrystallines spinel were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction(XRD), Thermal gravimetric (TGA), Scanning electron microcopy (SEM) with the energy dispersive X-ray spectroscopy (EDX) methods. The Specific surface area of the synthesized powders was measured with a Brunauer-Emmet-Teller (BET) apparatus using N2 adsorption. According to obtained XRD patterns the formation of single phase MAl2O4 completed up 800 °C. The average crystallite's sizes spinel and specific surface area at 800 °C were estimated about 11.07 nm and 154 m2 g−1, respectively. The results of SEM analysis show that the nanoparticles shape are as spherical shape, uniform and a little agglomerated. The magnetic behavior of spinels showed the magnetization decreased with increasing nickel ions. Adsorption of Cr(VI) by as prepared spinels were considered. The highest percent of Cr(VI) adsorption was occurred at contact time of 45 min, pH 7.0, and adsorbent dose of 2 g L−1. The order of adsorption capacity of sorbent samples for Cr(VI) removal was as follow: Ni0.5Cu0.5Al2O4 >Ni0.7Cu0.3Al2O4 >Ni0.3Cu0.7Al2O4>NiAl2O4> CoAl2O4. Kinetic studies indicated that the adsorption process follows by pseudo second-order model. Thermodynamic results revealed that the adsorption of Cr(VI) is endothermic, spontaneously process and feasible in the range of 298–338 K.

Изучение влияния параметров получения пористого коллагенового материала на его сорбционные свойства

In this work, the dependences of the sorption properties of the porous polymeric materials prepared from the cross- linked collagen on their composition and process specifications were studied. The optimal concentration of glutaraldehyde as a cross-linking agent was 0.5 wt %, the mass ratio of fish and leather waste was 1:1, and the drying temperature was 25 °C. Sorbent samples prepared using optimal parameters were effective in the sorption of petroleum products.

Optimisation of conditions for deacetylation of chitin-containing raw materials

The paper describes the differences between chitosan and chitin, and reviews works by foreign scientists on obtaining chitosan from various raw materials. Methods of modifying chitosan and obtaining combined sorbents have been analysed. It has been studied whether chitosan is applicable in the technology of wines and alcoholic beverages as a sorbent. The purpose of the study was determining the optimal conditions of the deacetylation stage to obtain chitosan with the best sorption properties from Aspergillus niger biomass. A three-factor experiment has been carried out. It involved obtaining 27 samples of chitosan using sequential four-step acid-base hydrolysis under various conditions of the deacetylation stage. The deacetylation process was optimised under alkaline conditions depending on the alkali concentration, processing temperature, and exposure. For each of the samples obtained, the adsorption activity, specific surface area, and distribution coefficient in the sorbent–sorbate system have been determined. The degrees of deacetylation of all chitosan samples have been determined by potentiometric titration. The study has resulted in determining the optimal conditions for the deacetylation stage: processing temperature 110–130°C, sodium hydroxide concentration 27–36 g/dm3, exposure 45 to 65 minutes. The sample deacetylated at the temperature 120 °C, alkali concentration 30 g/dm3, and exposure 45 minutes has shown the best adsorption activity values: the adsorption activity for methyl orange 347.96 mg/g, the specific surface area of the sorbent samples 0.52·105 m2/g, the distribution coefficient in the sorbent–sorbate system 3.29·10-3 ml/g. This sample had the highest degree of deacetylation, 43.6%. The sample has been analysed using IR spectroscopy, and its main characteristic frequencies have been studied. It has been concluded that the sample obtained was equivalent to the reference chitosan

Measurement of Diacetyl and Related Compounds in Coffee Roasteries and Breweries.

α-Diketones such as diacetyl (2,3-butanedione) and 2,3-pentanedione are generated during the roasting and fermentation of foods and are also used as flavoring compounds. Exposure to these compounds has been associated with obliterative bronchiolitis in workers. We report indoor air concentrations of diacetyl and 2,3-pentanedione, as well as acetoin (3-hydroxy-2-butanone), in several small coffee roasteries and breweries using standard integrated air sampling sorbent tubes followed by gas chromatography tandem mass spectrometry as well as the first use of on-site continuous real-time proton-transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS). Diacetyl and 2,3-pentanedione were detected in most of the sorbent samples at concentrations between 0.02 and 8 ppbv, and in general were higher in coffee roasteries compared with breweries. Three integrated air samples, all from the barista area at one facility, exceeded the NIOSH recommended exposure limit (REL) of 5 ppbv for diacetyl. 2,3-Pentanedione concentrations in these three samples were greater than 50% of its REL, but did not exceed it. Acetoin, a precursor to diacetyl, was also detected at concentrations between 0.03 and 5 ppbv in most sorbent tube samples, with concentrations generally higher in breweries. PTR-ToF-MS measurements exhibited similar trends and provided continuous real-time volatile organic compound data that showed episodic excursions with peak concentrations of diacetyl and 2,3-pentanedione between 15 and 20 ppbv. Examination of the time series data identified specific activities associated with peak diketone emissions, including transfer of freshly roasted coffee beans to the cooling tray, or the opening of a brew kettle. Additional indoor air quality parameters including CO2, NO2, and PM2.5 were also assessed on-site. Airway inflammation was assessed in 19 workers before and after each work shift using online measurements of fractional exhaled nitric oxide (FENO). The pre-shift mean FENO was 3.7 (95% confidence interval: -3.6, 11.0) ppbv higher and the post-shift FENO was 7.1 (-1.9, 16.1) ppbv higher for workers at coffee roasteries compared with breweries. The cross-shift change in FENO was 3.4 (-2.8, 9.6) ppbv higher for workers at coffee roasteries compared with breweries. However, none of these differences were statistically significant, and the cross-shift change in FENO was not statistically different from zero for either group of workers. The findings from this pilot study demonstrate that α-diketones and related compounds are present in the indoor air of both breweries and coffee roasteries and may exceed health protective guidelines in coffee roasteries. Additional studies are required to fully characterize worker exposures in these settings and to identify specific work activities and processes associated with high exposures. Engineering controls, including targeted exhaust ventilation and the use of low-cost sensors, are recommended as an approach to protect workers from exposure to hazardous levels of α-diketones.

Application of carbon monolith based on exfoliated graphite for sorption and subsequent chromatographic determination of volatile organic compounds in soil air

The possibility of using a new graphene-based carbon monolith for searching new oil deposits or branches adjacent to the already registered oilfields by areal geochemical survey is demonstrated. The material has been developed at the Faculty of Chemistry of M. V. Lomonosov Moscow State University. Sorption of volatile organic compounds (VOCs) from soil air at the oilfield was carried out using two sorbents (carbon adsorbent and Tenax-TA traditionally used for such analyses) with subsequent determination by gas chromatography with mass spectrometric detection and thermal desorption as a way of sample injection (TD/GC/MS). The new material absorbs more hydrocarbons (n-alkanes and monoaromatics) in the range from C8 to C16 than Tenax-TA, the intensities of the chromatographic peaks of the compounds also being higher. The phenomenon of irreversible sorption from carbon materials is observed for VOCs from C17 and more. However, the concentration of such substances in the soil air is rather low due to the low pressure of saturated vapors of these compounds under normal conditions. Hence, the chromatogram of carbon monolith reflects the macro-characteristics of this oil deposit better than Tenax-TA. To increase the sensitivity of the determination, a preliminary optimization of thermal desorption conditions was carried out. The values of the helium flow rate through the sorbent sample and the desorption time of the compounds are chosen to get the largest peak area. The regeneration of sorbent samples is carried out to provide the possibility of their reusage. Tenax-TA decomposes at lower temperatures compared to carbon sorbent and thus cannot be purified completely unlike the new monolith. The graphene-based sorbent is reusable and much cheaper in the manufacture than imported polymer Tenax-TA since it is made of domestic materials.

The influence of solid-phase organic carbon on the sorption of hydrophobic organic pollutants in landfill barriers, UK

The Oxford Clay from Bletchley, the Kimmeridge Clay from Kimmeridge Bay, Dorset, and Tertiary mud (Wittering Formation) from Whitecliff, Isle of Wight, United Kingdom were used as sorbent samples because of their distinctive organic material characteristics (Amorphous organic matter rich and/or phytoclast rich). Organic material was isolated for identification and analysis using a non-acid extraction method (heavy liquid) extraction and traditional methods involving HF digestion. These organic materials were then used to determine influences of extraction on hydrophobic organic contaminants, (toluene and naphthalene) sorption. Organic petrology classification was applied to identify the various types of isolated organic material. Amorphous organic matter from the Kimmeridge Clay displayed a higher sorption capacity (Sorption–desorption distribution coefficient (Kd), Kd = 6,481, 59, 670; for toluene and naphthalene, respectively) compared to literature values. Amorphous organic matter-rich sorbent extracts demonstrated a higher absorption capacity than the phytoclast-rich sorbents (e.g., Wittering Formation, Kd = 219, 10, 134; for toluene and naphthalene, respectively). Implications of results in landfill design/risk assessment and modelling are discussed.