Industrial Solvent Research Articles

Ozone episodes during and after the 2018 Chinese National Day holidays in Guangzhou: Implications for the control of precursor VOCs

The impact of reducing industrial emissions of volatile organic compounds (VOCs) on ozone (O3) pollution is of wide concern particularly in highly industrialized megacities. In this study, O3, nitrogen oxides (NOx) and VOCs were measured at an urban site in the Pearl River Delta region during the 2018 Chinese National Day Holidays and two after-holiday periods (one with ozone pollution and another without). O3 pollution occurred throughout the 7-day holidays even industrial emissions of VOCs were passively reduced due to temporary factory shutdowns, and the toluene to benzene ratios dropped from ∼10 during non-holidays to ∼5 during the holidays. Box model (AtChem2-MCM) simulations with the input of observation data revealed that O3 formation was all VOC-limited, and alkenes had the highest relative incremental reactivity (RIR) during the holiday and non-holiday O3 episodes while aromatics had the highest RIR during the non-pollution period. Box model also demonstrated that even aromatics decreased proportionally to levels with near-zero contributions of industrial aromatic solvents, O3 concentrations would only decrease by less than 20% during the holiday and non-holiday O3 episodes and ozone pollution in the periods could not be eliminated. The results imply that controlling emissions of industrial aromatic solvents might be not enough to eliminate O3 pollution in the region, and more attention should be paid to anthropogenic reactive alkenes. Isoprene and formaldehyde were among the top 3 species by RIRs in all the three pollution and non-pollution periods, suggesting substantial contribution to O3 formation from biogenic VOCs.

Retrofit of an industrial solvent recovery system: Distillation sequence intensification and simulation-based optimization

An industrial solvent recovery system in a rubber process consists of four distillation columns to recover solvent and unreacted 1,3-butadiene monomer. After the solvent is changed from raffinate oil to hexanes, it needs to investigate whether the current system can be retrofitted to reduce the number of columns and save energy. This work presents stepwise retrofit of the solvent recovery system by distillation sequence intensification and simulation-based optimization. Based on insights in distillation columns, an evolutionary strategy is introduced to generate intensified distillation sequences from the current distillation system. Next, a simulation-based optimization method considering comprehensive hydraulic evaluation is developed to obtain the best operating parameters of distillation columns. Seven distillation sequence alternatives to the current solvent recovery system are generated. The result indicates that the most compact sequence with two distillation columns can decrease the energy cost by 41.50%, while the preferred solution is a three-column sequence with the least modifications that reduces the energy cost by 33.13%. The proposed method also gives insights in energy saving and identifies bottlenecks to further improve the energy performance.

Long-term Trends and Sources of Atmospheric Halocarbons at Mount Taishan, Northern China

Halocarbons are hot topics in atmospheric environment and climate change research. Combining observational data from six field campaigns at the summit of Mount Taishan (36.25°N, 117.10°E, 1534 m above sea level) with backward trajectory and receptor source analyses, this study analyzed the long-term trends and major emission sources of halocarbons in the regional background atmosphere of the North China Plain (NCP) from 2003 to 2018. The results showed that the volume fraction of species eliminated by the Montreal Protocol (MP) showed a significant downward trend; however, the MP-controlled and unregulated species showed an overall upward trend. Meanwhile, the median volume fraction of the MP-controlled and unregulated species at Mount Taishan were significantly higher than the mid-latitude median background values in the northern hemisphere. Mount Taishan air was mainly affected by four types of air masses, of which the air mass originating from NCP accounted for the highest proportion (41%). The major sources of halocarbons were biomass/biofuel burning (38.1%), refrigeration (26.2%), industrial and domestic solvent use (21.7%), solvent use in the electronic industry (8.7%), and leakage of chlorofluorocarbon (CFCs) banks (5.3%). This study fully demonstrates that MP has been effectively implemented in China and provides evidence and recommendations to further reduce and control the volume fraction of halocarbons.

Decrease in ambient volatile organic compounds during the COVID-19 lockdown period in the Pearl River Delta region, south China

During the COVID-19 lockdown, ambient ozone levels are widely reported to show much smaller decreases or even dramatical increases under substantially reduced precursor NOx levels, yet changes in ambient precursor volatile organic compounds (VOCs) have been scarcely reported during the COVID-19 lockdown, which is an opportunity to examine the impacts of dramatically changing anthropogenic emissions on ambient VOC levels in megacities where ozone formation is largely VOC-limited. In this study, ambient VOCs were monitored online at an urban site in Guangzhou in the Pearl River Delta region before, during, and after the COVID-19 lockdown. The average total mixing ratios of VOCs became 19.1% lower during the lockdown than before, and those of alkanes, alkenes and aromatics decreased by 19.0%, 24.8% and 38.2%, respectively. The levels of light alkanes (C < 6) decreased by only 13.0%, while those of higher alkanes (C ≥ 6) decreased by 67.8% during the lockdown. Disappeared peak VOC levels in morning rush hours and the drop in toluene to benzene ratios during the lockdown suggested significant reductions in vehicle exhaust and industrial solvent emissions. Source apportioning by positive matrix factorization model revealed that reductions in industrial emissions, diesel exhaust (on-road diesel vehicles and off-road diesel engines) and gasoline-related emissions could account for 48.9%, 42.2% and 8.8%, respectively, of the decreased VOC levels during the lockdown. Moreover, the reduction in industrial emissions could explain 56.0% and 70.0% of the reductions in ambient levels of reactive alkenes and aromatics, respectively. An average increase in O3–1 h by 17% and a decrease in the daily maximum 8-h average ozone by 11% under an average decrease in NOx by 57.0% and a decrease in VOCs by 19.1% during the lockdown demonstrated that controlling emissions of precursors VOCs and NOx to prevent ambient O3 pollution in megacities such as Guangzhou remains a highly challenging task.

An analysis of the temporal variability in volatile organic compounds (VOCs) within megacity Seoul and an identification of their sources

In this study, the volume mixing ratio of 55 volatile organic compound (VOC) species was measured every hour using the online TD-GC-FID system during the period from January 2018 to December 2019 in Seoul. The most abundant species were ethane (10.0 ppbv) and toluene (4.1 ppbv), with alkanes and aromatics accounting for 57.5% and 31.5% of the total VOCs (TVOC), respectively. The mixing ratios of the TVOC were markedly higher in July and November, mainly owing to the presence of aromatics and alkanes, respectively, but were lower in other months, without any significant differences in other months. Of the aromatics, the maximum mixing ratios of xylene, benzene, and toluene were observed in summer, winter, and both seasons, respectively. Principal component analysis showed that emissions from traffic and solvent use were the main VOC sources, which were further categorized into liquefied natural gas/liquefied petroleum gas/gasoline, diesel fuel, mixed combustion, industrial solvents, and paint solvents. The two solvent sources were well represented by toluene and xylene, respectively. In addition, the distinct VOC composition of the air masses clustered by the back trajectory reveals the origin, seasonality, and transport characteristic of the five source categories. This study is the first report on multiyear variability of VOC mixing ratios in Seoul that highlights the contribution from evaporation sources and fugitive emissions and the potential impact of intercity transport from industrial areas near Seoul.

Isolation of toluene-degrading bacteria and investigation of the ability to decompose aromatic hydrocarbon mixture in laboratory wastewater

Toluene is an aromatic hydrocarbon commonly used as a solvent in industry and as one of the main components of gasoline. Due to its solubility in water, the compound may accumulate in surface water or reachgroundwater causing harmful effects on human health. Twenty bacterial strains grown on a minimal medium supplemented with toluene as the sole carbon source were isolated from the sediment samples of a laboratory wastewater treatment system. Among these, strains TL5 and TL27 performed toluene degradation capability. After 24 hours of incubation in a minimal medium supplemented with toluene (0.025% v/v) as the only carbon source, chromatographic data recorded that TL5 and TL27 degraded 96.71 and 100% toluene, respectively. In a minimal medium with a mixture of aromatic hydrocarbons added, after 4 days of incubation, toluene and benzaldehyde were completely degraded while phenol, xylene, acetophenone, and pyridine were degraded 88.27, 40.9, 34.67, and 23.26%, respectively. Based on 16S-rRNA sequence analysis, the potential aromatic hydrocarbon degrader was genetically identified as Enterobacter sp. TL27.

Non-covalent interactions in dimethylsulfoxide (DMSO) clusters and DFT benchmarking

Dimethylsulfoxide (DMSO) is one of the most used solvents in industries and in Chemistry. Understanding the dynamics of the solvent is subjected to the understanding of interactions in DMSO clusters. Despite its importance, a very few studies have been reported on DMSO clusters. In this work, we have explored thoroughly the potential energy surfaces (PESs) of the DMSO clusters from dimer to tetramer at the MP2/aug-cc-pVDZ level of theory. In order to understand the non-covalent interactions in DMSO clusters, we have performed a quantum theory of atoms in molecules (QTAIM) analysis. The QTAIM analysis showed that there are eight different types of non-covalent interactions stabilizing the DMSO clusters. The CH⋯O hydrogen bonding and H⋯H bonding are found to be the strongest and the weakest non-covalent interactions in DMSO clusters, respectively. In addition, we have reported the temperature-dependent isomer distribution of all the investigated clusters for temperatures ranging from 50 to 500 K. To allow affordable investigations of medium and large sized DMSO clusters in future investigations, we have assessed the performance of ten functionals of the density functional theory (DFT) in calculating the binding energies of the DMSO clusters. The ten DFT functionals (M05, M05-2X, M06, M06-2X, M08HX, PBE0, ωB97XD, PW6B95D3, APFD and MN15) have been benchmarked to MP2/CBS and DLPNO-CCSD(T)/CBS. The functionals PW6B95D3 and ωB97XD are recommended for further affordable investigations of the DMSO clusters.

Effect of styrene oxide and diethyl maleate on expression of cytochrome P450 family 1 and glutathione store in mouse liver

&#x0D; &#x0D; &#x0D; &#x0D; Purpose: To determine the effect of the glutathione (GSH) suppressors styrene oxide (SO) and diethyl maleate (DEM) on the hepatic expression of cytochrome P450 family 1 (Cyp1) isoforms that are related to carcinogenesis including Cyp1a1, Cyp1a2, and Cyp1b1.&#x0D; Methods: Seven-week-old ICR mice were intraperitoneally injected with SO (150 and 300 mg/kg/day), DEM (175 and 350 mg/kg/day), or N-acetylcysteine (NAC; 300 and 600 mg/kg/day) for 7, 14, or 28 days. Plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, hepatic Cyp1 expression, total glutathione, reduced glutathione (GSH), and oxidized glutathione (GSSG) were determined.&#x0D; Results: ALT and AST levels were markedly increased by SO and DEM while GSH/GSSG ratio was decreased by SO in all treatments (p &lt; 0.05), while high dose (350 mg/kg/day) DEM significantly suppressed GSH/GSSG ratio at 28 days (p &lt; 0.05). The expressions of Cyp1a1, Cyp1a2, and Cyp1b1 were induced by SO and DEM, corresponding with induction of ethoxy/methoxy-resorufin O- dealkylase activities.&#x0D; Conclusion: The Cyp1 family metabolizes procarcinogens to carcinogenic DNA adducts; exposure to the industrial solvents, SO and DEM, raises the risk of carcinogenesis via GSH depletion coupled with Cyp1 induction.&#x0D; &#x0D; &#x0D; &#x0D;

The industrial solvent 1,4-dioxane causes hyperalgesia by targeting capsaicin receptor TRPV1

BackgroundThe synthetic chemical 1,4-dioxane is used as industrial solvent, food, and care product additive. 1,4-Dioxane has been noted to influence the nervous system in long-term animal experiments and in humans, but the molecular mechanisms underlying its effects on animals were not previously known.ResultsHere, we report that 1,4-dioxane potentiates the capsaicin-sensitive transient receptor potential (TRP) channel TRPV1, thereby causing hyperalgesia in mouse model. This effect was abolished by CRISPR/Cas9-mediated genetic deletion of TRPV1 in sensory neurons, but enhanced under inflammatory conditions. 1,4-Dioxane lowered the temperature threshold for TRPV1 thermal activation and potentiated the channel sensitivity to agonistic stimuli. 1,3-dioxane and tetrahydrofuran which are structurally related to 1,4-dioxane also potentiated TRPV1 activation. The residue M572 in the S4-S5 linker region of TRPV1 was found to be crucial for direct activation of the channel by 1,4-dioxane and its analogs. A single residue mutation M572V abrogated the 1,4-dioxane-evoked currents while largely preserving the capsaicin responses. Our results further demonstrate that this residue exerts a gating effect through hydrophobic interactions and support the existence of discrete domains for multimodal gating of TRPV1 channel.ConclusionsOur results suggest TRPV1 is a co-receptor for 1,4-dioxane and that this accounts for its ability to dysregulate body nociceptive sensation.

Insights on choline chloride-based deep eutectic solvent (reline) + primary alcohol mixtures: a molecular dynamics simulation study.

Deep eutectic solvents (DESs) emerged as green solvents for new generation technologies owing to their high chemical and thermal stability. Addition of restricted amount of organic solvents into the DESs plays a significant role in the improvement of thermodynamic and the transport properties to work as a potential solvent in process industries. In this paper, molecular dynamics (MD) simulations were performed to understand the thermophysical and transport properties of choline chloride-based DES (reline) and primary alcohol (methanol and ethanol) mixture in relation to microscopic structure. Density, radial distribution function, coordination number, average number of H-bond, diffusion coefficient and spatial distribution function was calculated in order to understand the structure and involvement of H-bond network at an atomic level. H-bond and spatial distribution function analyses revealed that the chloride ion prefers to be spatially distributed around hydroxyl group of alcohol and found to be more pronounced upon increase in alcohol concentration. As a consequence, it was observed that the H-bonds between Cl- and urea decreases overall with the loading of alcohol and effect is more pronounced beyond a concentration of 0.4. Self-diffusion values for choline, Cl- and urea were found to be increased significantly upon increase in concentration of alcohol from 0.6 to 0.8. Overall, our simulation points to the interplay and interactions between the chloride ions and the solvents in determining the structural and transport properties of choline chloride-based DES.

Green solvents for extractive separation of Pb(II) and Hg(II) from various resources-An update

Heavy metals such as lead and mercury pollution are irreversible and stay for long time.The handling of wastes come out of industries, agriculture, domestic uses is very difficult to deal with. Hydro metallurgical technique like solvent extraction offers huge scope for the extraction,separation and purification of these waste materials in order to extract these metal values. The feasibility of ionic liquid as green solvents in the recovery of heavy metal ions like Pb(II) and Hg(II) from diverse resources are analyzed in this review. Ionic liquids, or salts having low melting temperature , have a number of benefits, including being long-lasting and environmentally friendly green solvents. Because of their specific attributes, like low vapour pressure, inflammability, less toxic character, appreciable ionic conductivity as well as a broad electrochemical potential window, these have got numerous application into diverse sectors, including hydro metallurgy. Despite the fact that a number of papers have been published on ionic liquids, pertinent research outcomes in the area of hydro metallurgical methods are very less. Due to the fact that investigation and use in this area are still in its early stages,more fundamental approaches to popularize these green solvents in the metal processing industries will be more challenging.Ammonium and phosphonium based ionic liquids have more stability than imidazolium based ionic liquids.Extraction process parameters like pH, time of extraction, extractant concentration, optimum temperature, volume ratio of both aqueous and organic phases in different extraction systems and their influences the extraction efficiency have been summarized.

Thermo-acoustic studies of ethyl propionate with propan-2-ol at different temperatures using ultrasonic technique

Binary/ternary mixtures are extensively used in manufacturing as they create a distinct reaction or structures when they are mixed with two or more liquids rather than the single one. The learning of thermodynamic properties of binary liquid mixtures has been evidenced to be a suitable tool in elucidating the interactions that are functioning between component molecules. In this investigation, the ultrasonic velocity, density and viscosity in ethyl propionate with propan-2-ol were measured at different temperatures of 308 K, 313 K, 318 K, 323 K, 328 K and 333 K. Ethyl propionate is used to manufacture various propionates used in the reduction of pharmaceuticals, anti-fungal agents, dyes, artificial flavours and perfumery synthetics. Propan-2-ol is used in the paints industry as a paint thinner and paint remover and is also used as a solvent in many industries. Acoustical parameters such as acoustic impedance (Z), adiabatic compressibility (βa), Intermolecular free length (Lf), relaxation time (τ), internal pressure (πi), Gibb’s free energy (Δ G) and enthalpy (H) have been computed from the above primary parameters. The variation of derived parameters was used to examine the structural changes and scope of interactions between the binary molecules and the obtained results have been discussed in detail.

Evaluation of Hydrogen Donation Ability of Industrial Hydrogen Storage Solvents by Radical Precursors

Evaluation of Hydrogen Donation Ability of Industrial Hydrogen Storage Solvents by Radical Precursors

Effect of Synthesis Routes on Microstructural Properties of Nano Zero-Valent Metals of Fe and Cu Synthesized from the Industrial Copper Solvent Extraction Process

Effect of Synthesis Routes on Microstructural Properties of Nano Zero-Valent Metals of Fe and Cu Synthesized from the Industrial Copper Solvent Extraction Process

Pyrolysis study of N, N-dimethylformamide at low pressure

N, N-dimethylformamide (DMF) is a kind of general solvent in Li-ion industry and nitrogen-containing component of amines fuels. The trace vapor of DMF is very harmful to human and environment, which could be treated by pyrolysis. The pyrolysis of DMF was newly carried out in a flow reactor at 30 Torr within 873–1273 K. Synchrotron radiation single photoionization coupled with molecular beam mass spectrometry was employed to detect the reactants, intermediates and products. 26 species were identified and quantified. Products related to NOx, such as nitrosomethane, nitrosyl cyanide and N-methylformamide were identified. With the temperature increasing, the mole fractions of species tend to increase monotonically, while nitrosyl cyanide, ethyl radical, cyclopropane, carbon monoxide, ethanol, acetaldehyde and ethanol exhibit peak-shaped curves. Hydrogen abstractions and dissociations are the main initial pathways of DMF consumption. As the main hydrocarbon products, methane and ethylene are predominantly formed by the H abstraction reaction by methyl radical and the β-scission of ethyl radical, respectively. Carbon monoxide is mainly generated from the dissociation of DMF and its mole fraction is at the same level as the fuel DMF. HCN is the most abundant product among all the carbonitride species via H abstraction of CH2 =NH as well as the collisions of CN with alkanes and aldehydes. These results provide a theoretical basis for further study of treating DMF in the exhaust fumes through pyrolysis and have reference value for the clean utilization of amine fuels.

Characteristics of Volatile Organic Compounds in the Pearl River Delta Region, China: Chemical Reactivity, Source, and Emission Regions

Volatile organic compounds (VOCs) are important precursors of photochemical ozone and secondary organic aerosol (SOA). Here, hourly variations of ambient VOCs were monitored with an online system at an urban site (Panyu, PY) in the Pearl River Delta region during August–September of 2020 in order to identify reactive VOC species and major sources of VOCs, OH loss rate (LOH), SOA formation potential (SOAFP), and corresponding emission source regions. The average concentration of VOCs at PY was 31.80 ± 20.82 ppbv during the campaign. The C2–C5 alkanes, aromatics, and ≥C6 alkanes contributed for the majority of VOC, alkenes and aromatics showed the highest contribution to LOH and SOAFP. Further, m/p-xylene, propene, and toluene were found to be the top three most reactive anthropogenic VOC species, with respective contributions of 11.6%, 6.1%, and 5.8% to total LOH. Toluene, m/p-xylene, and o-xylene constituted a large fraction of calculated SOAFP. Seven major sources were identified by using positive matrix factorization model. Vehicle exhaust made the most significant contribution to VOCs, followed by liquefied petroleum gas and combustion sources. However, industrial-related sources (including industrial solvent use and industrial process emission) had the largest contribution to LOH and SOAFP. By combining source contribution with wind direction and wind speed, the regions of different sources were further identified. Based on high-resolution observation data during ozone pollution, this study clearly exhibits key reactive VOC species and the major emission regions of different VOC sources, and thus benefits the accurate emission control of VOCs in the near future.

An improved control strategy for an industrial copper solvent extraction process

ABSTRACT In this paper, to solve the constraints and upgrade the control systems of industrial copper solvent extraction processes, an improved two-layer (optimization and stabilization) control strategy was proposed. The proposed control strategy is equipped with an advanced–step multistage nonlinear model predictive controller. It was successfully tested against simulated disturbances, noise and set point changes. Moreover, the proposed strategy was applied for an industrial process and the obtained results were compared to the plant control strategy and the latest proposed control strategy for industrial copper solvent extraction in the literature. With the proposed control strategy and the latest proposed control strategy in the literature, the production of the copper solvent extraction process was increased by almost 6% and 3%, respectively, compared to the plant control strategy, and the process variation was decreased by 90–92% and 80–85%, respectively.

Bio-hydrogen production from steam reforming of liquid biomass wastes and biomass-derived oxygenates: A review

Alternative energy sources have been the main interest since past decades due to inclining energy demand and growing environmental consciousness. Hydrogen (H2) which is known as a clean fuel and most viable energy carrier for the future, is highly potential due to its high mass-based energy density. Among the diverse thermochemical techniques introduced to generate H2 in an economical way, steam reforming (SR) emerged as a promising option due to high H2 production ability and economical profit. Presently, the feedstocks for mature SR technology are mostly non-renewable resources such as fossil fuel (coal, diesel, gasoline, and natural gas). H2 can also be produced from SR from alternative feedstocks such as liquid biomass waste and biomass derived oxygenates. This approach will not only solve disposal problem, but also open new breakthrough for renewable resources utilization. In this review, the concept, advantages, prospects and challenges of bio-H2 production via SR process over industrial effluents, solvents, biomass-derived solvents, and lipids are reviewed. These organic-rich feedstocks are mostly waste that caused pollution issues or produced in glut, thus proper utilization of these materials is an urgent need. SR of these alternative feedstocks are viable due to the high H2 yields obtained upon the transformation of their high-water volume content.

Quantitative tuning of ionic metal species for ultra-selective metal solvent extraction toward high-purity vanadium products

The essence behind metal solvent extraction is the interaction between metal species and organic extractants. Aqueous metal species tuning at the molecular level is critical to improve the extraction efficiency and selectivity of the target metal. Herein, we demonstrate a quantitative metal species tuning strategy which is capable of extracting the most critical metals (e.g., V, W, and Mo) in extraction systems constructed by amines. We reveal the superior activities of V4 and V10 species among various V and Cr species by calculations and experiments. In addition, the contribution of various Vn species was quantitatively evaluated via Ion Species Contribution Evaluation (ISCE). Our tuning strategy is rationally designed by bridging species characteristics and routine aqueous conditions with extraction activities. Consequently, a three-dimensional model of V and Cr solvent extraction is established for the prediction of reaction regions, and the reactivities of nearly 20 kinds of typical metal species are compared and predicted. Our strategy serves for industrial solvent extraction, and may provide inspiration for the traditional hydrometallurgical revolutionary.

Genetic Algorithm for Pressure-Swing Distillation Optimisation: Ethanol and Ethyl Acetate Mixture

In the acetic acid esterification, ethanol (EtOH) in excess is used to produce ethyl acetate (EtAc), which is commonly used as an organic solvent in biochemical and food industries. On the other hand, EtOH is useful considering the growing production of bioethanol for the fuel market. The resulting mixture of EtAc with unreacted EtOH forms an azeotrope which is difficult to separate by conventional distillation. Literature data shows that the azeotropic binary mixture EtOH – EtAc is separated mostly through extractive distillation. Unfortunately, this procedure has some drawbacks, such as high energy cost and environmental concerns (quite related to the extracting agent recovery). However, taking advantage of the azeotrope sensitivity on pressure, the extracting agent use can be avoided. This paper presents an optimal design for the separation of the above-mentioned mixture, using pressure-swing distillation (PSD) as separation process. In order to achieve a fully optimised system in terms of energy and capital, the method followed consists in simulating the process with Aspen Plus® and making use of genetic algorithms (GAs) to optimise the process variables, including, among others, the pressure of the high-pressure column. This process variable is of great importance, and from our point of view, this factor has not been properly studied nor discussed in literature so far. The starting population consists of points that group a set of values for all the design variables. These sets are a mixture of random and calculated values, obtained by application of heuristics, so that the initial population contains some potentially good initial individuals. The optimisation code is written in Visual Basic language and the link between Aspen Plus® and Visual Basic is also programmed so that a continuous connection can assure information flow from the optimisation program to Aspen Plus® and vice-versa.