Hasil untuk "Chemical technology"

Zhengyang Cai, Bilu Liu, X. Zou et al.

K. Ragaert, Laurens Delva, K. V. Van Geem

A. Rahimi, Jeannette M. García

M. B. Ahmed, John L. Zhou, H. Ngo et al.

V. Schroeder, Suchol Savagatrup, M. He et al.

Carbon nanotubes (CNTs) promise to advance a number of real-world technologies. Of these applications, they are particularly attractive for uses in chemical sensors for environmental and health monitoring. However, chemical sensors based on CNTs are often lacking in selectivity, and the elucidation of their sensing mechanisms remains challenging. This review is a comprehensive description of the parameters that give rise to the sensing capabilities of CNT-based sensors and the application of CNT-based devices in chemical sensing. This review begins with the discussion of the sensing mechanisms in CNT-based devices, the chemical methods of CNT functionalization, architectures of sensors, performance parameters, and theoretical models used to describe CNT sensors. It then discusses the expansive applications of CNT-based sensors to multiple areas including environmental monitoring, food and agriculture applications, biological sensors, and national security. The discussion of each analyte focuses on the strategies used to impart selectivity and the molecular interactions between the selector and the analyte. Finally, the review concludes with a brief outlook over future developments in the field of chemical sensors and their prospects for commercialization.

Lucas D. Ellis, Nicholas A. Rorrer, Kevin P. Sullivan et al.

Timmy Thiounn, Rhett C. Smith

the majority of high market-share plastics are obtained from the use of non-renewable and ecologically devastating and processing techniques. The imperative to access new technologies for recycling and plastics is clear given their unsustainable origins and dogged environmental persistence in the and 9 The current review aims to highlight contemporary academic efforts to develop new methods for recycling some of the most abundantly-produced plastics. Specifically, efforts chemically ABSTRACT The global production and consumption of plastics has increased at an alarming rate over the last few decades. The accumulation of pervasive and persistent waste plastic has concomitantly increased in landfills and the environment. The societal, ecological and economic problems of plastic waste/pollution demand immediate and decisive action. In 2015, only 9% of plastic waste was successfully recycled in the United States. The major current recycling processes focus on the mechanical recycling of plastic waste, however even this process is limited by the sorting/pretreatment of plastic waste and degradation of plastics during the process. An alternative to mechanical processes is chemical recycling of plastic waste. Efficient chemical recycling would allow for the production of feedstocks for various uses including fuels and chemical feedstocks to replace petrochemicals. This review focuses on the most recent advances for the chemical recycling of three major polymers found in plastic waste: poly(ethylene terephthalate) (PET), polyethylene (PE), and polypropylene (PP). Commercial processes for recycling hydrolysable polymers like polyesters or polyamides, polyolefins, or mixed waste streams are also discussed. ABSTRACT Advances and Approaches The global production and consumption of plastics has drastic societal and environmental ramifications. Chemical recycling of plastic waste is an alternative to traditional recycling methods that focuses on converting waste plastic into value-added chemicals for the synthesis of fuels, polymers, and other commodity chemicals. This review focuses on the most recent advances (2014–2019) in chemical recycling of some of the most widely produced plastics. A review with 113 references. This review covers the most common current academic and industrial effots to recycle common plastics and mixed waste.

Zheng Meng, Robert M Stolz, Lukasz Mendecki et al.

Electrically-transduced sensors, with their simplicity and compatibility with standard electronic technologies, produce signals that can be efficiently acquired, processed, stored, and analyzed. Two dimensional (2D) nanomaterials, including graphene, phosphorene (BP), transition metal dichalcogenides (TMDCs), and others, have proven to be attractive for the fabrication of high-performance electrically-transduced chemical sensors due to their remarkable electronic and physical properties originating from their 2D structure. This review highlights the advances in electrically-transduced chemical sensing that rely on 2D materials. The structural components of such sensors are described, and the underlying operating principles for different types of architectures are discussed. The structural features, electronic properties, and surface chemistry of 2D nanostructures that dictate their sensing performance are reviewed. Key advances in the application of 2D materials, from both a historical and analytical perspective, are summarized for four different groups of analytes: gases, volatile compounds, ions, and biomolecules. The sensing performance is discussed in the context of the molecular design, structure-property relationships, and device fabrication technology. The outlook of challenges and opportunities for 2D nanomaterials for the future development of electrically-transduced sensors is also presented.

J. Sempionatto, José A. Lasalde-Ramírez, Kuldeep Mahato et al.

Zhiliang Huang, M. Shanmugam, Zhaoiun Liu et al.

Chemical recycling is one of the most promising technologies that could contribute to circular economy targets by providing solutions to plastic waste; however, it is still at an early stage of development. In this work, we describe the first light-driven, acid-catalyzed protocol for chemical recycling of polystyrene waste to valuable chemicals under 1 bar of O2. Requiring no photosensitizers and only mild reaction conditions, the protocol is operationally simple and has also been demonstrated in a flow system. Electron paramagnetic resonance (EPR) investigations and density functional theory (DFT) calculations indicate that singlet oxygen is involved as the reactive oxygen species in this degradation process, which abstracts a hydrogen atom from a tertiary C–H bond, leading to hydroperoxidation and subsequent C–C bond cracking events via a radical process. Notably, our study indicates that an adduct of polystyrene and an acid catalyst might be formed in situ, which could act as a photosensitizer to initiate the formation of singlet oxygen. In addition, the oxidized polystyrene polymer may play a role in the production of singlet oxygen under light.

Lihui Lu, Wei-Mei Li, Yinghong Cheng et al.

The extensive production and consumption of plastics has resulted in significant plastic waste and plastic pollution. Polyvinyl chloride (PVC) waste has a high chlorine content and is the primary source of chlorine in the plastic waste stream, potentially generating hazardous chlorinated organic pollutants if treated improperly. This review discusses PVC synthesis, applications, and the current types and challenges of PVC waste management. Dechlorination is vital for the chemical recycling of PVC waste and PVC-containing plastic waste. We review dehydrochlorination and dechlorination mechanisms of PVC using thermal degradation and wet treatments, and summarize the recent progress in chemical treatments and dechlorination principles. This review provides readers with a comprehensive analysis of chemical recycling technologies for PVC waste and PVC-containing plastic waste to transform them into chemicals, fuels, feedstock, and value-added polymers.

Qizhou Chen, Ye Qi, Yuwei Jiang et al.

Chitosan, which is derived from chitin, is the only known natural alkaline cationic polymer. Chitosan is a biological material that can significantly improve the living standard of the country. It has excellent properties such as good biodegradability, biocompatibility, and cell affinity, and has excellent biological activities such as antibacterial, antioxidant, and hemostasis. In recent years, the demand has increased significantly in many fields and has huge application potential. Due to the poor water solubility of chitosan, its wide application is limited. However, chemical modification of the chitosan matrix structure can improve its solubility and biological activity, thereby expanding its application range. The review covers the period from 1996 to 2022 and was elaborated by searching Google Scholar, PubMed, Elsevier, ACS publications, MDPI, Web of Science, Springer, and other databases. The various chemical modification methods of chitosan and its main activities and application research progress were reviewed. In general, the modification of chitosan and the application of its derivatives have had great progress, such as various reactions, optimization of conditions, new synthetic routes, and synthesis of various novel multifunctional chitosan derivatives. The chemical properties of modified chitosan are usually better than those of unmodified chitosan, so chitosan derivatives have been widely used and have more promising prospects. This paper aims to explore the latest progress in chitosan chemical modification technologies and analyze the application of chitosan and its derivatives in various fields, including pharmaceuticals and textiles, thus providing a basis for further development and utilization of chitosan.

Fatma Delihasan Sonay, Barış Karslı, Emre Çağlak et al.

This study aims to develop nutritionally improved alternative fast-food products by incorporating anchovy (<i>Engraulis encrasicolus</i>), a fish with high nutritional value, into three popular fast-food items (toast, burger, and pizza) frequently consumed by fast-food consumers. Anchovies, due to their rich content of omega-3 fatty acids, high-quality protein, vitamins A and D, and minerals, are a valuable food source for public health. Within the scope of this study, the nutritional compositions (crude protein, crude fat, crude ash, moisture, carbohydrate, energy) and sensory properties of the developed products were determined. According to the results of the analysis, the highest crude protein (18.64%) and crude ash (4.38%) content were found in anchovy-enriched toast, while the highest crude fat content (10.82%) was observed in anchovy burger (<i>p</i> < 0.05). Sensory analyses indicated that the panelists generally accepted all products. Specifically, the anchovy-enriched burger received the highest scores for appearance (90%) and aroma (40%). These findings demonstrate that anchovy-enriched fast-food products are both nutritionally rich and consumer-accepted, nutritionally improved food alternatives. Furthermore, this study identifies significant potential for utilizing aquatic products within the nutritionally enriched, seafood-based product sector.

Shimshon Belkin

This review attempts to summarize my three decades-long involvement in, and contribution to, the design, construction and testing of bioluminescent microbial sensor strains (bioreporters). With the understanding that such a document cannot be completely free of bias, the review focuses on studies from my own lab only, with almost no coverage of the parallel progress made by others in similar fields. This admittedly subjective approach by no way detracts from the achievements of countless excellent researchers who are not mentioned here, and whose contributions to the field are at least as important as that of my own. The review covers basic aspects of microbial sensor design, and then progresses to describe approaches to performance improvement of sensor strains aimed at the detection of either specific chemicals, groups of chemicals sharing similar characteristics, or global effects, such as toxicity and genotoxicity. The need for integration of live sensor cells into a compatible hardware platform is highlighted, as is the importance of long-term maintenance of the cells’ viability and activity. The use of multi-member sensors’ panels is presented as a means for enhancing the detection spectrum and sample “fingerprinting”, along with a list of different purposes to which such sensors have been put to use.

Lynn Maria Schneider, Benedikt Sochor, Marcus Johansen et al.

Zhi-Rui Liu, Li-Lin Tan, Juan Gao et al.

For this research, three hydrophobically modified polyacrylamides, HPAAB, HPAAF, and HPAAS, with multiple hydrophobic monomers were designed, synthesized, and used as thickeners in aqueous ink for digital ink-jet printing. The structures were characterized by Fourier transform infrared (FTIR) analysis and nuclear magnetic resonance (NMR) spectroscopy. The viscosity–average molecular weight was determined by intrinsic viscosity determination and was adjusted according to hydrophobic content. The critical association concentration (CAC) of polymers was measured simultaneously using the apparent viscosity method and the fluorescence spectrum. The formation of a network structure and the mechanism of hydrophobic association are visualized dynamically with a scanning electron microscope (SEM) at different concentrations. Under the same conditions, HPAAB exhibited excellent thickening ability across different pH levels, temperatures, and shear rates, which is caused by the longer hydrophobic side chain and the stronger hydrophobic effect of the behenyl polyoxyethylene ether methacrylate (BEM) group. Furthermore, an aqueous ink using HPAAB as a thickener displays significant printability and stability, functioning much better than a corresponding aqueous ink that uses a commercial thickener. This is the first example of a hydrophobic associating polyacrylamide, incorporating both hydrophilic and hydrophobic units within a single hydrophobic chain, thereby serving as an efficient thickener for aqueous ink.

Xiaomeng Deng, Wensheng Wei, Zizhen Yan et al.

A meaningful and practical phenomenon was observed and investigated, about which a synthesized (2-hydroxyethyl) triethylammonium bromide (NEt3(HE)Br) was used for catalytic cycloaddition of PO (propylene oxide) and CO2 (carbon dioxide) in a homogeneous state, and then separated from the reaction system in a heterogeneous state. The target products were first reported as additives to regulate the distribution of reactants and carbon dioxide (CO2) in the gas-liquid phase, as well as to facilitate the dissolution of NEt3(HE)Br. Under the optimal conditions of 0.2 mol% NEt3(HE)Br dosage, the PC yield (98.71 %) and TOF value (22.54 h−1) reached are significantly higher than the case of without PC addition. Besides, NEt3(HE)Br exhibited impressive stability after five catalytic cycles. The catalytic performances of different additives (i.e., alcohols, cyclic carbonate, amides, sulfones, petroleum ether, straight-chain carbonate and oxalate) were investigated, and their promotional effects and mechanisms were systematically elucidated. The transition behavior of dissolution-catalysis-precipitation process and intrinsic promoting mechanism of NEt3(HE)Br gave an efficient idea for a homogeneous catalytic reaction and heterogeneous separation of the catalyst. Meanwhile, this work provides an important theoretical and practical basis for efficient and facile catalyst synthesis and the corresponding reaction system design.

Julien Guerrero, Ekaterina Maevskaia, Chafik Ghayor et al.

Additive manufacturing has emerged as a transformative tool in biomedical engineering, offering precise control over scaffold design for bone tissue engineering and regenerative medicine. While much attention has been focused on optimizing pore-based scaffold architectures, filament-based microarchitectures remain relatively understudied, despite the fact that the majority of 3D-printers generate filament-based structures. Here, we investigated the influence of filament characteristics on bone regeneration outcomes using a lithography-based additive manufacturing approach. Three distinct filament-based scaffolds (Fil050, Fil083, and Fil125) identical in macroporosity and transparency, crafted from tri-calcium phosphate (TCP) with varying filament thicknesses and distance, were evaluated in a rabbit model of bone augmentation and non-critical calvarial defect. Additionally, two scaffold types differing in filament directionality (Fil and FilG) were compared to elucidate optimal design parameters. Distance of bone ingrowth and percentage of regenerated area within scaffolds were measured by histomorphometric analysis. Our findings reveal filaments of 0.50 mm as the most effective filament-based scaffold, demonstrating superior bone ingrowth and bony regenerated area compared to larger size filament (i.e., 0.83 mm and 1.25 mm scaffolds). Optimized directionality of filaments can overcome the reduced performance of larger filaments. This study advances our understanding of microarchitecture’s role in bone tissue engineering and holds significant implications for clinical practice, paving the way for the development of highly tailored, patient-specific bone substitutes with enhanced efficacy.

Xin Meng, Fang Wang, Chao-Hong Fu et al.

Osmanthus fragrans is an evergreen shrub with a pleasant fragrance and a wide range of applications in many fields. The condensed hydrolat obtained during the drying process of its fresh flowers was collected in a low-temperature vacuum environment and its sensory evaluation and volatile components were studied. The main aroma compounds in Osmanthus fragrans were dihydro-β-ionone, nonanal, β-cyclocitral, β-ionone, benzaldehyde, α-ionone, and 6-methyl-5-hepten-2-one, whose contents were used as the main evaluation criteria, and the hydrolats obtained under different scenting and drying times were compared. This process can effectively collect the aroma components in Osmanthus fragrans and the optimal drying conditions were 50 °C for 5 h. The hydrolat was used to provide the scent of osmanthus black tea, which had a fresher and mellower taste, while the fragrance of osmanthus was abundant. These results show that osmanthus hydrolat can be used to provide the scent of floral black tea. Chemical compounds studied in this article: (−)-Catechin (PubChem CID: 1203); (−)-epigallocatechin gallate (PubChem CID: 65064); (−)-epicatechin gallate (PubChem CID: 367141); (−)-epigallocatechin (PubChem CID: 72277); (−)-epicatechin (PubChem CID: 72276); (−)-gallocatechin gallate (PubChem CID: 199472); (−)-catechin gallate (PubChem CID: 6419835); (−)-gallocatechin (PubChem CID: 9882981).

Younggill Son, Woongchul Choi

With the global surge in electric vehicle (EV) deployment, driven by enhanced environmental regulations and efforts to reduce transportation-related greenhouse gas emissions, managing the life cycle of Li-ion batteries becomes more critical than ever. A crucial step for battery reuse or recycling is the precise estimation of static capacity at retirement. Traditional methods are time-consuming, often taking several hours. To address this issue, a machine learning-based approach is introduced to estimate the static capacity of retired batteries rapidly and accurately. Partial discharge data at a 1 C rate over durations of 6, 3, and 1 min were analyzed using a machine learning algorithm that effectively handles temporally evolving data. The estimation performance of the methodology was evaluated using the mean absolute error (MAE), mean squared error (MSE), and root mean squared error (RMSE). The results showed reliable and fairly accurate estimation performance, even with data from shorter partial discharge durations. For the one-minute discharge data, the maximum RMSE was 2.525%, the minimum was 1.239%, and the average error was 1.661%. These findings indicate the successful implementation of rapidly assessing the static capacity of EV batteries with minimal error, potentially revitalizing the retired battery recycling industry.