Isopropanol Concentration Research Articles

Selective Recovery of Polyphenols from Discarded Blueberries (Vaccinium corymbosum L.) Using Hot Pressurized Liquid Extraction Combined with Isopropanol as an Environmentally Friendly Solvent.

The use of water-ethanol mixtures in hot pressurized liquid extraction (HPLE) to recover phenolic compounds from agro-industrial waste has been successfully investigated. However, the unresolved challenge of reducing solvent costs associated with the process hinders the scaling of this eco-friendly technology. This study evaluated the use of isopropanol as an alternative, lower-cost solvent for recovering polyphenols from discarded blueberries through the HPLE process. HPLE was carried out using water-isopropanol mixtures (0, 15 and 30%) at 70, 100, and 130 °C. The total polyphenol content (TPC), antioxidant capacity (DPPH and ORAC), glucose and fructose contents, and polyphenol profile of the extracts were determined. HPLE extracts obtained using high isopropanol concentrations (30%) and high temperatures (130 °C) presented the highest TPC (13.57 mg GAE/gdw) and antioxidant capacity (IC50: 9.97 mg/mL, ORAC: 246.47 µmol ET/gdw). Moreover, the use of 30% water-isopropanol resulted in higher yields of polyphenols and removal of reducing sugars compared to atmospheric extraction with water-acetone (60%). The polyphenolic profiles of the extracts showed that flavanols and phenolic acids were more soluble at high concentrations of isopropanol (30%). Contrarily, flavonols and stilbenes were better recovered with 15% isopropanol and pure water. Therefore, isopropanol could be a promising solvent for the selective recovery of different bioactive compounds from discarded blueberries and other agro-industrial residues.

Preparation and characterization of high catalytic performance supported TS-2 zeolites for phenol hydroxylation

Good inter-grown TS-2 zeolites layer is successfully prepared on the outer surface of porous millimeter α-Al2O3 sphere by secondary hydrothermal synthesis. The supported TS-2 zeolites are loaded into a fixed-bed catalytic reactor for catalyzing phenol hydroxylation by hydrogen peroxide, which could efficiently avoid the fussy separation process. Influences of synthesis parameters on Ti active micro-environment, crystal morphology and catalytic performance of the supported TS-2 zeolites are investigated in this work, medium isopropanol content is necessary for preparing fine and homogenous TS-2 zeolites layer on the porous α-Al2O3 sphere. Besides, formation process of the supported TS-2 zeolites is studied in this study, which divided into three stages, dissolution of seed crystals, formation of novel nuclei, growth and aggregation of TS-2 zeolites layer. When the titanium source, isopropanol/SiO2 and TiO2/SiO2 molar ratio of the initial synthesis gel are tetrabutyl titanate, 1.0 and 0.035, tetra-coordinated titanium containing and compact TS-2 zeolites layer are fully covered on the α-Al2O3 sphere, the optimum phenol conversion and dihydroxybenzene selectivity of the zeolites are 40.07% and 98.52% at 65 °C.

New choice of energy battery electrode materials in new energy vehicles: preparation of graphene aerogels by γ ray irradiation method

Graphene aerogel are frequently employed as electrode materials for power batteries due to their high specific surface area and excellent properties. This paper presents a method for preparing graphene aerogel by radiolytic reduction in a water and isopropanol system. In this study, the authors used radiolytic reduction technology to reduce graphene oxide to graphene aerogel and investigated the effects of various factors in the water and isopropanol system on its preparation process and properties. The experimental results showed that the water and isopropanol system could effectively prepare graphene aerogel with a high specific surface area, and the isopropanol concentration and irradiation time in the isopropanol system had important effects on its properties. This preparation method has the advantages of simplicity, rapidity, and low cost, providing a new idea for the large-scale preparation of graphene aerogel.

Estimating exposures from spray products using robotic simulations.

There is an increasing need for exposure data to enable more precise information for risk estimates and improved public health protection. While personal monitoring data are preferred, it is often difficult to collect due to the resources needed to complete a human research study. In this study, we successfully programmed a robotic arm to mimic human use (spraying) of a fabric crafts protector (FCP) and human cleaning (spraying and wiping) of a glass pane with glass cleaner (GC). The robot was then used in place of human subjects to assess inhalation exposures to volatile organic compounds (VOCs) during the use of the FCP and GC. Air sampling data were collected while the robot used the products to estimate personal exposures to VOCs. Average VOC concentrations were 1.57 ppm for FCP spraying and 0.17 ppm for GC spraying and wiping. During FCP spraying, average acetone concentrations were 0.88 ppm and average isopropyl alcohol concentrations were 0.26 ppm. During GC spraying and wiping, average 2-butoxyethanol concentrations were 0.15 ppm. Air sampling data were found to be within the range of data reported in the literature during human use of similar glass cleaning products. No data was found in the literature during use of fabric protector spray products. This study contributes exposure measurement data with detailed contextual information to help characterize inhalation exposures during the use of 2 spray products. In addition, the study offers a systematic, efficient method for generating exposure data which can be used to improve health and safety risk assessments used for public health protection.

Hydrophobic tuning of PDMS-PVDF hollow fiber membranes for enhanced isopropanol recovery in pentane diol production process via pervaporation

BackgroundsThis study explores a use of crosslinked polydimethylsiloxane (PDMS) membranes for the selective pervaporation separation of isopropanol (IPA) from a mixture of 1,2 and 1,5 pentanediols (PeD). MethodsTwo crosslinkers, tetraethyl orthosilicate (TEOS) and 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FDTS), were used to prepare PDMS coating on inside of polyvinylidene fluoride (PVDF) hollowfiber membrane. Significant findingsSeparation performance of PDMS-FDTS membrane outperformed to that of PDMS-TEOS membrane. Both of the PDMS membrane systems resulted a high IPA selectivity, was attributed to the nonpolar nature of IPA and its strong interaction with hydrophobic PDMS chain. An operating conditions influenced the pervaporation performance, with higher feed temperature increasing flux but reducing IPA content in permeate. An increasing IPA content in the feed mixture increased flux while slightly decreasing the separation factor. Overall, PDMS-FDTS membranes demonstrated promising performance for selective IPA removal and yielded a flux in the range of 173 ± 15 g/m2h while maintaining the IPA content in permeate higher than 99.7% at 60 °C, which showed potential for industrial-scale applications due to its high flux and selectivity.

Mining of a novel reductase and its application for asymmetric reduction of p-methoxyacetophenone.

(R)-1-(4-methoxyphenyl) ethanol [(R)-1b] is an essential precursor for the synthesis of aryl propanoic acids' anti-inflammatatory drugs. Biocatalysts for (R)-1b preparation are limited and reductase has problems of low substrate concentration and low conversion rate. As a result, there is a constant need for discovering novel biocatalysts with excellent catalytic performances. In this study, a novel reductase LpSDR from Lacisediminihabitans profunda for the biocatalytic reduction of p-methoxyacetophenone (1a) to (R)-1b was obtained based on gene-mining technology, and some key reaction parameters were also investigated to improve the conversion rate of 1a using whole cells of recombinant Escherichia coli expressing reductase LpSDR as biocatalysts. It was found that the optimal concentration of isopropanol, ZnSO4·7H2O solution, 1a, and recombinant E. coli resting cells, the optimal reaction temperature, buffer pH, and reaction time were 1.95mol l-1, 0.75mmol l-1, 75mmol l-1, 250g (wet weight) l-1, 28°C, 7.0, and 21 h, respectively. Under the above conditions, a conversion rate of 99.5% and an enantiomeric excess of 99.6% were obtained, which were superior to the corresponding values previously reported. This study provides a novel reductase LpSDR, which is helpful in reducing 1a to (R)-1b.

Development of integrated volatile organic compound purification system using tubular NaA zeolite membrane: Experimental and theoretical insights into vapor permeation and pervaporation process

This study experimentally and theoretically investigated the dehydration performance of vapor permeation (VP) and pervaporation (PV) processes using tubular NaA zeolite membranes. The effects of the key operating conditions (e.g., feed flow rate, concentration, temperature, and permeate pressure) on the dehydration performance of each process were experimentally investigated using a binary mixture of isopropanol and water. In addition, detailed mathematical models were developed to investigate the separation behavior in the VP and PV processes. The prediction results were validated using experimental results from the VP and PV processes (relative error < 5%). Additionally, based on the developed VP and PV processes, an integrated system for the purification of volatile organic compounds (VOCs) was proposed and evaluated. The integrated VOCs purification system consisted of a two-stage VP process (once-through mode) and single-stage PV process (recycling mode). The isopropanol from the binary mixture (74 wt% isopropanol and 26 wt% water) was recovered at a rate of 99.9% via the two-stage VP process, with an isopropanol concentration of 96.67%. Moreover, the isopropanol recovered from the VP process was upgraded to 99.23 wt% via the PV process. The simulation results showed that the integrated system obtained isopropanol with a concentration of 99.97 wt% with a recovery of 97.10% from the binary VOCs mixture.; this was in good agreement with the experimental results (relative error < 3%).

Assessment of quality of commercial hand sanitizers using Fourier transform infrared spectroscopy and gas chromatography

Since the beginning of the COVID-19 pandemic, the use and manufacture of alcohol-based hand sanitizers increased exponentially. Efficacy of hand sanitizers mainly depends on active ingredients like ethanol and isopropanol (IPA). Even though methanol is extremely hazardous to people, it is still illegally used in hand sanitizers in Bangladesh. Developing a quick and simple analytical method for detecting and quantifying ethanol/IPA/methanol is crucial. Here, Fourier transform infrared spectroscopy (FTIR) was used to identify and quantify alcohol content in commercially available hand sanitizers in a quick and easy way. Comparing the FTIR and GC data, provided quite similar results. Unlike previous studies by FTIR, C–H, CH3–C–CH3 stretching, and C–H bending vibrational modes were employed to construct analytical calibration curves to detect and quantify alcohol in hand sanitizers. According to FTIR and GC findings, ethanol and IPA content were found to be 43–82% and 40–69%, and 56–64% and 61–66%, respectively, whereas ethanol was labeled at 66–80% and IPA at 65–70%. FTIR and GC revealed methanol content ranging from 37 to 98 and 19 to 81%, respectively. Also, the FTIR was significantly faster than the GC. Therefore, FTIR can be used to commercially analyze the quality of hand sanitizers.•FTIR was used to identify and quantify alcohol content in commercially available hand sanitizers in a quick and easy way.•Comparing the FTIR and GC data, provided quite similar results.•Out of ten samples, five contained ethanol, three IPA, and two methanol.

Effect of isopropanol on CO2 capture by activated carbon: Adsorption performance and regeneration capacity

Globally, fossil fuel combustion from various industrial processes has caused a significant increase in CO2 emissions, exacerbating the greenhouse effect and climate change. Therefore, effective CO2 capture technologies must be urgently developed. Vacuum temperature swing adsorption (VTSA) is an efficient technique for CO2 capture. The presence of water vapor, H2S, etc., is an important factor that affects the performance of CO2 adsorption, and they are usually removed prior to the adsorption separation process. However, volatile organic compounds (VOCs), a common component of industrial flue gas, can also affect the adsorption and capture of CO2, which is often ignored. Thus, in this study, the effect of isopropanol (IPA), one of the most common VOCs used in industry, on the CO2 removal performance is examined using an in-house VTSA device with activated carbon (AC) as the adsorbent. The effect of IPA on the CO2 adsorption performance of AC under varying IPA concentration, IPA content in AC, feed flow rate, and adsorption/desorption temperature is comprehensively investigated. The results verify that the impact of VOCs in the industrial exhaust gases on CO2 capture by adsorption cannot be disregarded.

Synthesis of a highly selective organophilic membrane for pervaporative recovery of isopropyl alcohol from water

Isopropyl alcohol (IPA) selective membranes were prepared from poly(methyl methacrylate-co-butyl acrylate) copolymers based on their relative solubility parameter values. Several such copolymers were synthesized by varying the methyl methacrylate (MMA) and butyl acrylate (BA) molar ratios. The membranes prepared from these copolymers were characterized and used for pervaporative recovery of IPA from water in a dead end -cross flow pervaporation(PV). The effect of MMA molar% of the membranes and the feed concentration of IPA on the total flux(J), permeability(P), separation factor(βPV) and membrane selectivity (α) for IPA were also studied. The effect of concentration polarisation was eliminated at a feed flow rate of 80 mL/min. Accordingly, for 4 wt% IPA in feed the membrane prepared from the copolymer containing 92 M% MMA showed a thickness normalised flux of 56.7µmkgm-2h−1 and βPV of 62 for IPA in PV with a feed flow rate of 100 mL/min. The 4 wt% IPA in the feed was concentrated to 72.06% after PV.

Experimental study on separation of isopropanol-water azeotrope by packed capillary distillation and the prediction model of artificial neural network

ABSTRACT Capillary distillation is an azeotropic distillation technology, which combines the mechanism of surface adsorption, capillary action, as well as the distillation process. Different variations of activity coefficient and saturated vapor pressure of azeotropic components occur in the capillary pore structure, which leads to the separation. In this paper, 5A, 4A, and 3A molecular sieve capillary porous media were selected as capillary packing to study the separation effect on azeotropic mixture of isopropanol-water solution experimentally. It was found that 4A molecular sieve worked better, the best reflux ratio is 6, and the best packing height is 0.4 m. Based on the abovementioned experimental results, a back propagation (BP) neural network is developed and utilized in the separation process. The effects of parameters such as the composition of feedstock solution, reflux ratio, and packing height on the concentration of isopropyl alcohol at the top of packed capillary distillation column were predicted, and the accuracy reached 96.7%. The proposed prediction method is helpful for developing the technology of separating azeotropic solution by capillary distillation with packing suitable for industrial application.

KrF excimer laser for Pt–NPs synthesis by PLAL in isopropanol solution and their use in a SERS application

Pulsed laser ablation in aqueous isopropanol (IPA) solution (PLAL) using KrF excimer laser was employed for the first time to produce platinum nanoparticles (Pt–NPs). The dependence of their optical and morphological properties on the IPA concentration and ablation time at certain values of the laser fluence (LF) and repetition rates (RR), was investigated. The UV/Vis transmission (T) spectra of the Pt–NPs were measured to assess indirectly their type, relative mean size (MS) and standard deviation (SD). Peculiarities of this spectra, related to the presence of a volatile component in the solution are discussed. Morphological properties as shape, MS, SD, and microstructure were studied via High-Resolution Scanning Transmission Electron Microscopy (HR-STEM). The created Pt–NPs show spherical shape with smallest MS value of 1.7 nm using 2.3 Jcm−2 LF, 10 Hz RR and 10 min ablation time in 80% aqueous IPA solution and the narrowest SD of ±0.7 nm with the same technological parameters but using 30% IPA concentration. The Pt nature of the NPs was confirmed by Energy Dispersive X-Ray technique. The crystallographic structure was determined by HR-STEM and X-ray diffraction measurements. An application of the synthesized Pt–NPs is presented using their role as substrate in methylene blue through surface-enhanced Raman spectroscopy method.

Biocide Susceptibility and Antimicrobial Resistance of Escherichia coli Isolated from Swine Feces, Pork Meat and Humans in Germany.

Phenotypic susceptibility testing of Escherichia (E.) coli is an essential tool to gain a better understanding of the potential impact of biocide selection pressure on antimicrobial resistance. We, therefore, determined the biocide and antimicrobial susceptibility of 216 extended-spectrum β-lactamase-producing (ESBL) and 177 non-ESBL E. coli isolated from swine feces, pork meat, voluntary donors and inpatients and evaluated associations between their susceptibilities. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of benzalkonium chloride, chlorhexidine digluconate (CHG), chlorocresol (PCMC), glutaraldehyde (GDA), isopropanol (IPA), octenidine dihydrochloride and sodium hypochlorite (NaOCl) showed unimodal distributions, indicating the absence of bacterial adaptation to biocides due to the acquisition of resistance mechanisms. Although MIC95 and MBC95 did not vary more than one doubling dilution step between isolates of porcine and human origin, significant differences in MIC and/or MBC distributions were identified for GDA, CHG, IPA, PCMC and NaOCl. Comparing non-ESBL and ESBL E. coli, significantly different MIC and/or MBC distributions were found for PCMC, CHG and GDA. Antimicrobial susceptibility testing revealed the highest frequency of resistant E. coli in the subpopulation isolated from inpatients. We observed significant but weakly positive correlations between biocide MICs and/or MBCs and antimicrobial MICs. In summary, our data indicate a rather moderate effect of biocide use on the susceptibility of E. coli to biocides and antimicrobials.

The danger of the toxicity and inefficacy of alcohol-based hand rubs in Iran during COVID-19: a cross-sectional study

BackgroundThe use of disinfectants and alcohol-based hand rubs (ABHR) to prevent COVID-19 transmission increased in the first wave of the infection. To meet the increased demand, the Iranian Ministry of Health issued an emergency use authorization allowing new manufacturers to enter the market, despite the limited capacity for surveillance of these products during COVID-19. Methanol poisoning outbreaks spread rapidly, and more people died from methanol poisoning than COVID-19 in some cities. The aim of this study was to analyze some ABHRs in the Iranian market to see if (a) ABHRs are standard and suitable for hand antisepsis and (b) contained potentially dangerous toxic alcohols.MethodBetween February and March 2020, 64 brands of ABHR were conveniently collected from pharmacies, supermarkets, and shops selling hygienic products and analyzed using Gas Chromatography. World Health Organization and Food and Drug Administration guidelines were used to define minimum requirements for ABHR. For estimating the risk for acute methanol poisoning, we assumed a serum methanol concentration of 200 mg/L following ABHR ingestion was sufficient to cause intoxication. This threshold concentration would be achieved in an average 75-kg adult after consuming 8000 mg (or eight grams) methanol in 1–2 h.ResultsThe median [IQR] (range) concentration of ethanol, isopropanol, and methanol were 59% v/v [32.2, 68] (0, 99), 0 mg/L [0, 0] (0, 197,961), and 0 mg/L [0, 0] (0, 680,100), respectively. There was a strong negative correlation between methanol and ethanol contents of hand rubbers (r= -0.617, p < 0.001). Almost 47% of ABHRs complied with minimum standards. In 12.5% of ABHRs, high concentrations of methanol were observed, which have no antiseptic properties but could cause acute methanol poisoning if ingested.ConclusionCOVID-19 initiated a policy for distribution and use of ABHR with little control. As ABHR and masks are still accepted preventive measures of the disease, non-standard ABHR compositions may increase the population’s risk to both COVID-19 infection and methanol poisoning.

Synthesis of Carboxyl Modified Polyether Polysiloxane Surfactant for the Biodegradable Foam Fire Extinguishing Agents.

It is necessary to develop novel and efficient alternatives to fluorocarbon surfactant and prepare fluorine-free environmentally-friendly fire extinguishing agent. The carboxyl modified polyether polysiloxane surfactant (CMPS) with high surface activity was synthesized via the esterification reaction using hydroxyl-containing polyether modified polysiloxane (HPMS) and maleic anhydride (MA) as raw materials. The process conditions of the esterification reaction were optimized by orthogonal tests, and the optimum process parameters were determined as follows: reaction temperature of 85 °C, reaction time of 4.5 h, isopropyl alcohol content of 20% and the molar ratio of HPMS/MA of 1/1. The chemical structure, surface activity, aggregation behavior, foam properties, wetting properties and electron distribution were systematically investigated. It was found that the carboxyl group was successfully grafted into silicone molecule, and the conjugated system was formed, which changed the interaction force between the molecules and would affect the surface activity of the aqueous solution. The CMPS exhibited excellent surface activity and could effectively reduce the water's surface tension to 18.46 mN/m. The CMPS formed spherical aggregates in aqueous solution, and the contact angle value of CMPS is 15.56°, illustrating that CMPS had excellent hydrophilicity and wetting performance. The CMPS can enhance the foam property and has good stability. The electron distribution results indicate that the introduced carboxyl groups are more inclined towards the negative charge band, which would be conducive to weak the interaction between molecules and improve the surface activity of the solution. Consequently, new foam fire extinguishing agents were prepared by using CMPS as a key component and they exhibited excellent fire-fighting performance. The prepared CMPS would be the optimal alternative to fluorocarbon surfactant and could be applied in foam extinguishing agents.

Research on Spontaneous Diffusion and Fragmentation of Liquid Droplets Caused by Marangoni Effect

The Marangoni effect is important to drying silicon wafers, the fields of welding and improving engine liquid fuel efficiency. In this paper, we investigate the Marangoni flow caused by the evaporation of droplets of alcohol solution, which eventually causes the droplet "atomization" phenomenon. The Marangoni convection phenomenon was studied in terms of temperature and droplet concentration, and the changes of droplet diffusion and the degree of droplet "atomization" were investigated after droplets of different volume concentrations of Isopropyl Alcohol (IPA) were added to different solutions.

Effect of Isopropanol on the Fluorescence of Crude Oil-in-Water Dispersions

Fluorescence spectroscopy is a promising technique to quantify crude oil-in-water because it provides information on both dissolved and dispersed molecules. One of the challenges of measuring properties of dispersions is the creaming of droplets, mainly due to density differences with the continuous phase. The addition of isopropanol to oil-in-water dispersions is an often-recommended trick to prevent the creaming of dispersed oil and obtain more reproducible measurements. Although isopropanol does not in itself fluoresce, the aim of the present work was to investigate if the emission from crude oil-in-water would be affected by the addition of isopropanol. The data set comprised synchronous fluorescence and emission spectra of 193 samples of crude oil-in-water/isopropanol mixtures, with oil concentrations varying from 10 to 1271 mg L–1 covering typical concentrations along the water treatment system offshore and isopropanol mass fractions from 0 to 1. Selected spectral features were used as input for principal component analysis, from which it was observed that the samples clustered into three groups. The isopropanol content in each mixture and, consequently, the dielectric constants were found to be the main underlying factors driving the shape and intensity of the emission bands. In the range of 0.01 to 0.5 w/w of isopropanol, the samples became milky which cleared at higher isopropanol content. Additional experiments showed that significant changes in the spectral shapes and emission intensities were observed more as a function of the isopropanol content than of the actual oil concentration. Furthermore, the quantum yield of crude oil is highly dependent on the isopropanol-to-water fraction, which means that adding isopropanol to crude oil-in-water dispersions is not advisable for oil quantification purposes by fluorescence spectroscopy.

Comparison of plasmid stabilization systems during heterologous isopropanol production in fed-batch bioreactor

Strain robustness during production of recombinant molecules is of major interest to ensure bioprocess profitability. The heterogeneity of populations has been shown in the literature as a source of instability in bioprocesses. Thus, the heterogeneity of the population was studied by evaluating the robustness of the strains (stability of plasmid expression, cultivability, membrane integrity and macroscopic cell behavior) during well-controlled fedbatch cultures. On the context of microbial production of chemical molecules, isopropanol (IPA) has been produced by recombinant strains of Cupriavidus necator. Plasmid stability was monitored by the plate count method to assess the impact of isopropanol production on plasmid stability, depending on implanted plasmid stabilization systems for strain engineering designs. With the reference strain Re2133/pEG7c, an isopropanol titer of 15.1 g·L−1 could be achieved. When the isopropanol concentration has reached about 8 g. L−1, cell permeability increased (up to 25 %) and plasmid stability decreased significantly (up to 1.5 decimal reduction rate) resulting in decreased isopropanol production rates. Bioprocess robustness under isopropanol producing conditions was then investigated with two plasmid construction strategies (1) Post Segregational Killing hok/sok (in Re2133/pEG20) and (2) expression of GroESL chaperon proteins (in Re2133/pEG23). Plasmid stability for strain Re2133/pEG20 (PSK hok/sok) appears to be improved up to 11 g. L−1 of IPA compared to the reference strain (8 g. L−1 IPA). Nevertheless, cell permeability followed the same dynamic as the reference strain with a drastic increase around 8 g. L−1 IPA. On the contrary, the Re2133/pEG23 strain made it possible to minimize the cell permeability (with a constant value at 5 % IP permeability) and to increase the growth capacities in response to increased isopropanol concentrations but plasmid stability was the weakest. The metabolic burden, linked to either the overexpression of GroESL chaperones or the PSK hok/sok system, seems to be deleterious for the overall isopropanol production compared to the reference strain (RE2133/pEG7c) even if we have shown that the overexpression chaperones GroESL improve membrane integrity and PSK system hok/sok improve plasmid stability as long as isopropanol concentration does not exceed 11 g L− 1.

Separation of volatile organic contaminants from water using a direct-contact dehumidifier: An experimental study and modeling

A packed-bed, direct-contact dehumidifier (PB-DCD) has been developed to selectively condense water from a gaseous mixture of organic contaminants. In this process, hot air is humidified by mixing with wastewater vapor in a static mixer and is dehumidified by subcooled fresh water passing through the PB-DCD in a counter-current configuration. The goal of this study is to understand the relationship between various operating parameters and how they affect separation of isopropyl alcohol (IPA) from the gaseous mixture with the purpose of expanding the investigation to other contaminants in the future. The process has been successfully used to separate IPA from wastewater. Different parameters including the concentration of IPA in water, feed temperature, air-to-vapor ratio, and cooling-water-to-vapor mass ratio, as well as residence time were examined to determine their influence on contaminant separation and clean water recovery rate. The Buckingham Pi theorem was applied to reduce the number of studying variables by generating non-dimensional groups. Experiments were performed to determine the relationship between the non-dimensional parameters and model mass transfer in the system. Mass transfer coefficients for multicomponent gaseous mixture condensation in a packed-bed direct contact condenser column are calculated and a modified correlation of mass transfer is developed. The parameters of the mass transfer model are obtained from operating conditions of the PB-DCD, stream conditions and thermodynamic properties. A modified Sherwood correlation is developed to predict IPA separation from a gaseous mixture consisting of air, water, and IPA. The modified Sherwood correlation is applied to successfully predict the Sherwood number with a mean absolute error equal to 6.6 %. According to the experimental results, the maximum IPA separation achieved was 76.3 %, which corresponds to a water recovery rate of 58.7 %.

The Impact of Donor Preparation for Tissue Procurement on Postmortem Vitreous Isopropanol Concentration.

Volatile chemicals can be relevant in the determination of the cause and manner of death by forensic pathologists. Isopropanol is a secondary alcohol that is occasionally seen on postmortem toxicology testing. A series of 11 forensic autopsy cases was previously reported in which the presence of isopropanol in the vitreous humor was suspected to be due to postmortem contamination from the body preparation process for tissue procurement.In collaboration with a tissue procurement agency, donor vitreous humor was collected from one eye before body preparation for procurement and from the other eye postpreparation. The specimens underwent testing for volatile substances by headspace gas chromatography.Of the 50 cases, 8 (16%) showed statistically significant changes in the prepreparation and postpreparation isopropanol concentrations. Postpreparation isopropanol concentrations ranged from 5 to 104 mg/dL (median, 18 mg/dL). Seven of the 8 cases had undetectable prepreparation isopropanol, whereas the remaining case had a detectable prepreparation isopropanol.In conclusion, surface contamination of the decedent's body with chemicals used in body preparation can lead to the passive absorption into the body, resulting in the presence of isopropanol in postmortem toxicology samples. Forensic pathologists need to be aware of this when interpreting postmortem samples after tissue procurement.