Hasil untuk "Chemical technology"

S. Koohi-Fayegh, M. Rosen

Abstract Energy storage technologies, including storage types, categorizations and comparisons, are critically reviewed. Most energy storage technologies are considered, including electrochemical and battery energy storage, thermal energy storage, thermochemical energy storage, flywheel energy storage, compressed air energy storage, pumped energy storage, magnetic energy storage, chemical and hydrogen energy storage. Recent research on new energy storage types as well as important advances and developments in energy storage, are also included throughout.

I. Vollmer, Michael J F Jenks, M. Roelands et al.

Abstract Increasing the stream of recycled plastic necessitates an approach beyond the traditional recycling via melting and re‐extrusion. Various chemical recycling processes have great potential to enhance recycling rates. In this Review, a summary of the various chemical recycling routes and assessment via life‐cycle analysis is complemented by an extensive list of processes developed by companies active in chemical recycling. We show that each of the currently available processes is applicable for specific plastic waste streams. Thus, only a combination of different technologies can address the plastic waste problem. Research should focus on more realistic, more contaminated and mixed waste streams, while collection and sorting infrastructure will need to be improved, that is, by stricter regulation. This Review aims to inspire both science and innovation for the production of higher value and quality products from plastic recycling suitable for reuse or valorization to create the necessary economic and environmental push for a circular economy.

Phil de Luna, C. Hahn, Drew C. Higgins et al.

BACKGROUND As the world continues to transition toward carbon emissions–free energy technologies, there remains a need to also reduce the carbon emissions of the chemical production industry. Today many of the world’s chemicals are produced from fossil fuel–derived feedstocks. Electrochemical conversion of carbon dioxide (CO2) into chemical feedstocks offers a way to turn waste emissions into valuable products, closing the carbon loop. When coupled to renewable sources of electricity, these products can be made with a net negative carbon emissions footprint, helping to sequester CO2 into usable goods. Research and development into electrocatalytic materials for CO2 reduction has intensified in recent years, with advances in selectivity, efficiency, and reaction rate progressing toward practical implementation. A variety of chemical products can be made from CO2, such as alcohols, oxygenates, synthesis gas (syngas), and olefins—staples in the global chemical industry. Because these products are produced at substantial scale, a switch to renewably powered production could result in a substantial carbon emissions reduction impact. The advancement of electrochemical technology to convert electrons generated from renewable power into stable chemical form also represents one avenue to long-term (e.g., seasonal) storage of energy. ADVANCES The science of electrocatalytic CO2 reduction continues to progress, with priority given to the need to pinpoint more accurately the targets for practical application, the economics of chemical products, and barriers to market entry. It will be important to scale CO2 electrolyzers and increase the stability of these catalysts to thousands of hours of continuous operation. Product separation and efficient recycling of CO2 and electrolyte also need to be managed. The petrochemical industry operates at a massive scale with a complicated global supply chain and heavy capital costs. Commodity chemical markets are difficult to penetrate and are priced on feedstock, which is currently inexpensive as a result of the shale gas boom. CO2 capture costs from the flue or direct air and product separation from unreacted CO2 are also important to consider. Assuming that the advancement of electrocatalytic technologies continues apace, what will it take to disrupt the chemical production sector, and what will society gain by doing so? This review presents a technoeconomic and carbon emissions assessment of CO2 products such as ethylene, ethanol, and carbon monoxide, offering target figures of merit for practical application. The price of electricity is by far the largest cost driver. Electrochemical production costs begin to match those of traditional fossil fuel–derived processes when electricity prices fall below 4 cents per kWh and energy conversion efficiencies reach at least 60%. When powered by renewable electricity, these products can be made with a net negative carbon emissions footprint. A comparative analysis of electrocatalytic, biocatalytic, and fossil fuel–derived chemical production shows that electrocatalytic production has the potential to yield the greatest reduction in carbon emissions, provided that a steady supply of clean electricity is available. Additionally, opportunities exist to combine electrochemical conversion of CO2 with a range of other thermo- and biocatalytic processes to slowly electrify the existing petrochemical supply chain and further upgrade CO2 into more useful chemicals. Technical challenges such as operating lifetime, energy efficiency, and product separation are discussed. Supply chain management of products and entrenched industrial petrochemical competition are also considered. OUTLOOK There exists increasingly widespread recognition of the need to transition to carbon emissions–free means of chemical production. CO2 pricing mechanisms are being developed and are seeing increased governmental support. The nascent carbon utilization economy is gaining traction, with startup companies, global prizes, and industrial research efforts all pursuing new carbon conversion technologies. Recent advances in electrochemical CO2 reduction through the use of gas diffusion electrodes are pushing current densities and selectivities into a realm of industrial use. Despite this progress, there remain technical challenges that must be overcome for commercial application. Additionally, market barriers and cost economics will ultimately decide whether this technology experiences widespread implementation. Electrochemical CO2 conversion. Reduction of CO2 using renewably sourced electricity could transform waste CO2 emissions into commodity chemical feedstocks or fuels. Electrocatalytic transformation of carbon dioxide (CO2) and water into chemical feedstocks offers the potential to reduce carbon emissions by shifting the chemical industry away from fossil fuel dependence. We provide a technoeconomic and carbon emission analysis of possible products, offering targets that would need to be met for economically compelling industrial implementation to be achieved. We also provide a comparison of the projected costs and CO2 emissions across electrocatalytic, biocatalytic, and fossil fuel–derived production of chemical feedstocks. We find that for electrosynthesis to become competitive with fossil fuel–derived feedstocks, electrical-to-chemical conversion efficiencies need to reach at least 60%, and renewable electricity prices need to fall below 4 cents per kilowatt-hour. We discuss the possibility of combining electro- and biocatalytic processes, using sequential upgrading of CO2 as a representative case. We describe the technical challenges and economic barriers to marketable electrosynthesized chemicals. Science, this issue p. eaav3506

Nagy L. Torad, Mohamad M. Ayad

Since the discovery of conducting polymers (CPs), their unique properties and tailor-made structures on-demand have shown in the last decade a renaissance and have been widely used in fields of chemistry and materials science. The chemical and thermal stability of CPs under ambient conditions greatly enhances their utilizations as active sensitive layers deposited either by in situ chemical or by electrochemical methodologies over electrodes and electrode arrays for fabricating gas sensor devices, to respond and/or detect particular toxic gases, volatile organic compounds (VOCs), and ions trapping at ambient temperature for environmental remediation and industrial quality control of production. Due to the extent of the literature on CPs, this chapter, after a concise introduction about the development of methods and techniques in fabricating CP nanomaterials, is focused exclusively on the recent advancements in gas sensor devices employing CPs and their nanocomposites. The key issues on nanostructured CPs in the development of state-of-the-art miniaturized sensor devices are carefully discussed. A perspective on next-generation sensor technology from a material point of view is demonstrated, as well. This chapter is expected to be comprehensive and useful to the chemical community interested in CPs-based gas sensor applications.

Huanyu Jin, Chunxia Guo, Xin Liu et al.

S. Khalid, M. Shahid, N. Niazi et al.

R. Kishor, D. Purchase, G. Saratale et al.

Abstract Textile industry wastewater (TIWW) is considered as one of the worst polluters of our precious water and soil ecologies. It causes carcinogenic, mutagenic, genotoxic, cytotoxic and allergenic threats to living organisms. TIWW contains a variety of persistent coloring pollutants (dyes), formaldehyde, phthalates, phenols, surfactants, perfluorooctanoic acid (PFOA), pentachlorophenol and different heavy metals like lead (Pb), cadmium (Cd), arsenic (As), chromium (Cr), zinc (Zn) and nickel (Ni) etc. TIWW is characterized by high dye content, high pH, chemical oxygen demand (COD), biochemical oxygen demand (BOD), total dissolved solids (TDS), total suspended solids (TSS), total organic carbon (TOC), chlorides and sulphates. Thus, requires adequate treatment before its final discharge into the water bodies to protect public health and environment. The treatment of TIWW is a major challenge as there is no particular economically feasible treatment method capable to adequately treat TIWW. Therefore, there is a need to develop a novel, cost-effective and eco-friendly technology for the effective treatment of TIWW. This review paper emphasizes on the different textile industry processes, wastewater generation, its nature and chemical composition, environmental impacts and health hazards and treatment approaches available for TIWW treatment. It also presents various analytical techniques used to detect and characterize TIWW pollutants and their metabolites, challenges, key issues and future prospectives.

Jeannette M. García, Megan L. Robertson

E. S. Sanz-Pérez, C. R. Murdock, S. Didas et al.

Joseph H. Montoya, L. Seitz, Pongkarn Chakthranont et al.

S. Linic, U. Aslam, Calvin Boerigter et al.

J. Rissman, C. Bataille, E. Masanet et al.

Abstract Fully decarbonizing global industry is essential to achieving climate stabilization, and reaching net zero greenhouse gas emissions by 2050–2070 is necessary to limit global warming to 2 °C. This paper assembles and evaluates technical and policy interventions, both on the supply side and on the demand side. It identifies measures that, employed together, can achieve net zero industrial emissions in the required timeframe. Key supply-side technologies include energy efficiency (especially at the system level), carbon capture, electrification, and zero-carbon hydrogen as a heat source and chemical feedstock. There are also promising technologies specific to each of the three top-emitting industries: cement, iron & steel, and chemicals & plastics. These include cement admixtures and alternative chemistries, several technological routes for zero-carbon steelmaking, and novel chemical catalysts and separation technologies. Crucial demand-side approaches include material-efficient design, reductions in material waste, substituting low-carbon for high-carbon materials, and circular economy interventions (such as improving product longevity, reusability, ease of refurbishment, and recyclability). Strategic, well-designed policy can accelerate innovation and provide incentives for technology deployment. High-value policies include carbon pricing with border adjustments or other price signals; robust government support for research, development, and deployment; and energy efficiency or emissions standards. These core policies should be supported by labeling and government procurement of low-carbon products, data collection and disclosure requirements, and recycling incentives. In implementing these policies, care must be taken to ensure a just transition for displaced workers and affected communities. Similarly, decarbonization must complement the human and economic development of low- and middle-income countries.

R. Ramakrishnan, Pavlo O. Dral, Pavlo O. Dral et al.

Computational de novo design of new drugs and materials requires rigorous and unbiased exploration of chemical compound space. However, large uncharted territories persist due to its size scaling combinatorially with molecular size. We report computed geometric, energetic, electronic, and thermodynamic properties for 134k stable small organic molecules made up of CHONF. These molecules correspond to the subset of all 133,885 species with up to nine heavy atoms (CONF) out of the GDB-17 chemical universe of 166 billion organic molecules. We report geometries minimal in energy, corresponding harmonic frequencies, dipole moments, polarizabilities, along with energies, enthalpies, and free energies of atomization. All properties were calculated at the B3LYP/6-31G(2df,p) level of quantum chemistry. Furthermore, for the predominant stoichiometry, C7H10O2, there are 6,095 constitutional isomers among the 134k molecules. We report energies, enthalpies, and free energies of atomization at the more accurate G4MP2 level of theory for all of them. As such, this data set provides quantum chemical properties for a relevant, consistent, and comprehensive chemical space of small organic molecules. This database may serve the benchmarking of existing methods, development of new methods, such as hybrid quantum mechanics/machine learning, and systematic identification of structure-property relationships. Design Type(s) in silico design • data integration Measurement Type(s) Computational Chemistry Technology Type(s) quantum chemistry computational method Factor Type(s) level of theory Design Type(s) in silico design • data integration Measurement Type(s) Computational Chemistry Technology Type(s) quantum chemistry computational method Factor Type(s) level of theory Machine-accessible metadata file describing the reported data (ISA-Tab format)

S. Nanda, F. Berruti

J. Heikenfeld, A. Jajack, J. Rogers et al.

Wearable sensors have recently seen a large increase in both research and commercialization. However, success in wearable sensors has been a mix of both progress and setbacks. Most of commercial progress has been in smart adaptation of existing mechanical, electrical and optical methods of measuring the body. This adaptation has involved innovations in how to miniaturize sensing technologies, how to make them conformal and flexible, and in the development of companion software that increases the value of the measured data. However, chemical sensing modalities have experienced greater challenges in commercial adoption, especially for non-invasive chemical sensors. There have also been significant challenges in making significant fundamental improvements to existing mechanical, electrical, and optical sensing modalities, especially in improving their specificity of detection. Many of these challenges can be understood by appreciating the body's surface (skin) as more of an information barrier than as an information source. With a deeper understanding of the fundamental challenges faced for wearable sensors and of the state-of-the-art for wearable sensor technology, the roadmap becomes clearer for creating the next generation of innovations and breakthroughs.

H. Ali, Ezzat Khan, M. Sajad

D. L. Robinson, Andre Hermans, Andrew T. Seipel et al.

Lixia Feng, Qilong Bian, Shujun Wu et al.

Abstract Arsenic contaminants exist in different chemical forms with varying toxicity and mobility, making on-site analysis challenging. Here, a fluorogenic method is developed for the efficient detection of arsenite and arsenate ions using a portable platform directly in an aqueous phase. During sensing, the aggregation-induced emission (AIE) probe TPE-Cys/TPE-2Cys exhibits low fluorescence when dissolved, but reacts with the As(III) to form organic arsenic complexes with low solubility, inducing a turn-on fluorescence for quantitative analysis. Using a prior reduction strategy, the As(V) can be converted to As(III) and further analyzed in a sequential detection. Using a specialized laser-induced fluorescence instrument, this strategy allows on-site analysis of As(III) and As(V) species with sensitivity down to 0.14 ppb in environmental samples, showing that As(III) dominates while the As(V)/As(III) ratio varies in a constitutional equilibrium. The system has potential for the practical analysis of complex arsenic, revealing the dynamic arsenic transformations in the environment.

ZHANG Qian, LIANG Jiamin, XU Tengyu, XIAO Xiong, CHEN Xiong, LI Xin

Our laboratory had isolated a strain of non-Saccharomyces yeast with significant application potential from high-temperature Daqu, Lachancea thermotolerans Y-07. This study aimed to explore the interaction of L. thermotolerans Y-07 with Aspergillus oryzae M-08 and Saccharomyces cerevisiae BS-19 when used for mixed culture fermentation of Baijiu under gradient temperature conditions and to evaluate its impact on Baijiu quality. To this end, changes in biomass, sensory quality, organic acids and volatile flavor compounds were examined during the fermentation process. The results demonstrated that L. thermotolerans Y-07 produced β-phenylethanol, reduced the higher alcohol content, and significantly improved the sensory quality of Baijiu, indicating its positive role in Baijiu brewing. High-temperature conditions not only helped maintain yeast diversity during the fermentation process, but also enhanced aroma richness. The presence of S. cerevisiae BS-19 increased the biomass of L. thermotolerans Y-07 by 21.63%. Under high-temperature conditions, the presence of S. cerevisiae BS-19 facilitated the recovery and proliferation of L. thermotolerans Y-07. This study provides important insights into the mechanism of action of L. thermotolerans in Baijiu brewing and the influence of temperature on microbial interactions during the fermentation process.

Yi-Wei Zhao, Li-Li Du, Bing Hu et al.

Nitrous oxide (N2O) emissions from the wastewater treatment sector are a significant contributor to global greenhouse gas levels. This investigation delves into the mechanisms of N2O generation and uptake, correlating microbial processes with variables such as influent characteristics and operational parameters. The nature of carbon substrates in the influent profoundly influences microbial consortia and N2O output. Elevating the carbon-to-nitrogen (C/N) ratio has been shown to curtail N2O emissions by alleviating the competitive dynamics among denitrifying enzymes. Optimal activity of N2O reductase is achieved by maintaining a neutral to mildly alkaline pH and stable ambient temperatures. It is imperative to circumvent extreme aeration rates and prolonged aeration periods to reduce N2O release. The study underscores the importance of an effective carbon feed strategy and advocates for prolonged hydraulic retention times (HRT) and sludge retention times (SRT) in activated sludge suspension systems to inhibit N2O escape. Notably, excessive internal recycling, coupled with heightened dissolved oxygen (DO) levels in aerobic zones, intensifies N2O emission risks. Moreover, the presence of hazardous contaminants, such as heavy metals and antibiotics, interferes with nitrogen elimination processes, warranting a comprehensive assessment of consequent N2O emission hazards. This research provides a scientific basis as well as practical management approaches to diminish N2O emissions.