Electrochemical exfoliation of graphite has been regarded as a potential approach to produce graphene on a large scale. Despite recent progress in the production of graphene with few defects by ...cathodic exfoliation, current methods suffer from uncontrolled thicknesses and limited yield. Here we devise a novel cathodic exfoliation method using diverse tetraalkylammonium cations in various non-aqueous solvents toward efficient preparation of high-quality graphene. Sandwich-structured graphite electrode enables sufficient ion intercalation and uniform exfoliation into few-layer graphene (>80%, 1–3 layers), along with remarkable yield (91.5%) and ultralow defect density (ID/IG = 0.05). The interplay of electrolyte cation and solvent on its intercalation efficiency and electrochemical stability was also studied, which are in direct correlation with the exfoliation ability. Further mechanism investigation demonstrates that tetrabutylammonium cations in propylene carbonate can intercalate into graphite efficiently under reducing condition. Adjacent layers were then taken apart rapidly due to gas formation reactions, resulting in non-destructive exfoliation. The preparation process can be easily scaled up and yield a high production rate (exceeding 50 g h−1), demonstrating its potential to facilitate the mass production of high-quality graphene for extensive applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The aquatic ecosystem is one of the most delicate environments, housing a diverse range of organisms, including fish, all of which are exposed to a wide variety of pollutants. The accumulation of ...these harmful substances in fish, which are part of the human diet, presents a significant health risk to humans. In our study, we have optimized an extraction technique to determine the presence of 25 high production volume chemicals in liver and skin samples taken from commonly consumed fish species. We have employed ultrasound-assisted extraction in conjunction with gas chromatography tandem mass spectrometry to achieve this goal. Apparent recoveries of the method ranged from 50% to 111% for both sample types with some exceptions such as most of the benzosulfonamides and benzothiazole. Additionally, the method's detection and quantification limits varied from 0.1 to 1.7 ng g−1 (dry weight, d.w) and 0.2–4.5 ng g−1 (d.w), respectively. Our investigation focused on three frequently consumed fish species in Tarragona: sea bass, sea bream, and turbot. Almost all of the samples we analysed contained traces of contaminants, with phthalates being the most commonly detected. The highest concentrations were observed for diethyl phthalate, with levels peaking at 8350 ng g−1 (d.w.). Organophosphate esters, such as triethyl phosphate and tributyl phosphate, also showed notable presence, with peak concentrations of 93.6 and 34.0 ng g−1 (d.w.), respectively.
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•HPVC have been determined in fish and liver samples.•A method based on ultrasound-assisted extraction was optimized.•Most HPVC were present in the samples.•Benzothiazoles and benzosulfonamides determined for the first time in fish and liver.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Evaluating the occurrence of high production volume chemicals (HPVCs) and polycyclic aromatic hydrocarbons (PAHs) in the air is important because they carry a carcinogenic risk and can lead to ...respiratory or endocrine problems. Examples of HPVCs are organophosphate esters, benzosulfonamides, benzothiazoles, phthalate esters (PAEs), phenolic antioxidants and ultraviolet stabilizers. In this paper we develop a multi-residue method for determining HPVCs and PAHs in air samples via pressurized liquid extraction followed by gas chromatography-mass spectrometry. Air samples were collected by active sampling with high volume samplers using quartz fiber filter for the particulate matter (PM10) and polyurethane foams for gas phase. The compounds found at the highest concentrations were PAEs, with a concentration of up to 24 ng m−3 of DEHP in gas phase and up to 109 ng m−3 of DEHA in PM10. Non-carcinogenic risk assessment results ranged from 9.7E-05 to 9.5E-03 for most of the compounds studied. On the other hand, the results for carcinogenic risk showed that PAHs made the highest contribution.
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•New multiresidue method based on PLE/GC-MS to determine 38 HPVCs and 18 PAHs in outdoor air samples.•Particulate matter and gas phases were analyzed.•There were differences between PM10 and gas phase depending on the summer and winter months.•HPVCs have a lower risk contribution than PAHs for the population.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A multiresidue analytical method based on pressurised liquid extraction and gas-chromatography mass spectrometry was developed to determine 22 compounds belonging to different chemical families in ...indoor dust.: Seven organophosphate esters, six phthalate esters, three benzotriazoles, five benzothiazoles and four benzenesulfonamides were included in the present study, all of them belonging to the category of high production volume chemicals (HPVCs). Apparent recoveries ranged between 45% and 123% and method quantification limits ranged from 0.03 μg/g to 3.8 μg/g. The occurrence of the selected HPVCs was evaluated in indoor dust from different locations in the Tarragona (Catalonia, Spain) region. Two benzenesulfonamides, ortho-toluenesulfonamide and para-toluenesulfonamide, were detected in dust samples for the first time. Phthalate esters and organophosphate esters were the most abundant compounds found, and di-(2-ethylhexyl) phthalate (DEHP) was determined at the highest concentrations. With the data obtained, human exposure was assessed by calculating the estimated daily intakes (EDI) via ingestion and dermal contact. Non-carcinogenic and carcinogenic risk assessments found no risks in any of the scenarios tested, which included two age classes (children and adults) and two possible exposure scenarios (median and worst-case scenario), except for the evaluation of carcinogen risk due to ingestion of DEHP in the worst-case scenario.
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•New multiresidue method based on PLE/GC-MS to determine 22 HPVCs in indoor dust.•Phthalate and organophosphate esters were the most abundant HPVCs.•Two benzenesulfonamides were detected in dust for the first time.•EDIingestion and EDIdermal were evaluated.•Both non-carcinogenic and carcinogenic risk were assessed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Innovation in achieving solar energy access is growing.•Optimal operating conditions for a new route for polycrystalline silicon production.•The process was formulated as a nonlinear ...programming.•Optimization allows determining the optimal tradeoff between yield and energy consumption of the process.•New process in optimal operating conditions shows a competitive price of polycrystalline silicon, below the commercial price.
A hybrid polycrystalline silicon production route is optimized following a two-step procedure. First, surrogate models for the main units are developed following different techniques which depend on the available information. Secondly, the optimization of the entire process flowsheet allows determining the optimal tradeoff between yield and energy consumption. A base production capacity of 2000 t/y of polycrystalline silicon is considered, with an equipment cost of 9.97 M$. Three scenarios are evaluated: maximum silicon production, minimum operating costs and maximum total profit. The maximization of the total profit is the most promising scenario, obtaining a selling price of 8.93 $/kgPoly, below the commercial price, 10 $/kgPoly. The revenue obtained is 10 M$/y, with an operating cost of 6.48 M$/y. Furthermore, a plant scale-up study was performed. If the production capacity is increased by a factor of 10, it results in a reduction of 1.03 $/kgSiPoly.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Seafood plays an important role in diet because of its health benefits. However, the fact that chemical compounds such as high production volume chemicals may be present in seafood means that its ...consumption can be a potential risk for population. To assess the occurrence of HPVs and estimate the exposure and risk associated with their consumption, specimens of the most consumed seafood species in Catalonia and the Canary Islands, Spain, were collected and analysed. Results showed higher levels of HPVs in samples from Catalonia and a prevalence of phthalate esters and benzenesulfonamides over the other target compounds in samples from both locations. Multivariate analysis showed spatial differences between the mean concentration profiles of HPVs for the samples from Catalonia and the Canary Islands. Exposures were higher for the samples from Catalonia, although the intake of HPVs via seafood was not of any real concern in either of the locations.
•HPVs were detected in all the analysed seafood samples.•HPV profiles enable the differentiation of Catalonia and Canary Islands samples.•Catalonia and Canary Islands seafood consumption pose no risk towards population.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Compared with previously reported catalysts, zinc-containing talc exhibited the highest formation rate of 1,3-butadiene in one-step conversion of ethanol at 673K. Our results showed that talc ...containing just 1.4wt.% of ZnO produced 1,3-butadiene at a rate of 1.9×10−2molg−1h−1.
•Talc structure is crucial to produce butadiene from ethanol at a high formation rate.•A small amount of Zn in talc is also crucial for the butadiene production.•Zn in talc drastically prolongs the catalyst life.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Formalin is among the most important commodity chemicals, used mainly as a precursor to a wide range of value-added products. Currently, formalin is widely produced from methanol derived from natural ...gas, however a transition from fossil-based production to sustainable feedstocks and pathways is crucial. This study evaluates the environmental impacts of selected promising formalin production technologies to shape a pathway towards more sustainable production of key chemicals. Among the investigated production routes are through methane steam reforming of other fossil and renewable sources, hydrogenation of CO2, and direct conversion of methane, syngas or CO2. to formalin. A comparative Life Cycle Assessment (LCA) is performed for seven different formalin synthesis routes with higher readiness levels. Technologies utilizing waste CO2 and biogas from manure as feedstocks show the most promising results, reducing greenhouse gas footprint by roughly 60% compared to the conventional pathway. Results show that a key contribution to the environmental impact mitigation was the unburdening effect due to the use of waste and product's substitution. With this study, a more comprehensive outlook focusing on the environmental sustainability of formalin production is provided. Environmental performance and readiness levels of formalin production technologies utilizing renewable or waste feedstocks indicate that such pathways could be applied to industrial scale in the future.
•Formalin production routes with higher Technology Readiness Levels are studied.•Environmental impacts for selected formalin production technologies are evaluated.•Technologies utilizing waste CO2 and biogas from manure show promising results.•Greenhouse gas footprint is reduced by up to 60% compared to conventional pathway.•A key mitigation is unburdening effect due to waste use and product substitution.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
