Hasil untuk "Chemical industries"

I. Oller, S. Malato, J. A. Sánchez-Pérez

Deborah K Schneiderman, M. Hillmyer

I. Siró, D. Plackett

J. Holladay, Jianli Hu, D. King et al.

A. Basso, S. Serban

Abstract The use of immobilized enzymes is now a routine process for the manufacture of many industrial products in the pharmaceutical, chemical and food industry. Some enzymes, such as lipases, are naturally robust and efficient, can be used for the production of many different molecules and have a wide range of industrial applications thanks to their broad selectivity. As an example, lipase from Candida antarctica (CalB) has been used by BASF to produce chiral compounds, such as the herbicide Dimethenamide-P, which was previously made chemically. The use of the immobilized enzyme has provided significant advantages over a chemical process, such as the possibility to use equimolar concentration of substrates, obtain an enantiomeric excess > 99%, use relatively low temperatures ( 1 ]. Some more specific enzymes, like transaminases, have required protein engineering to become suitable for applications in production of APIs (Active Pharmaceutical Ingredients) in conditions which are extreme for a wild type enzyme. The process developed by Merck for sitagliptin manufacture is a good example of challenging enzyme engineering applied to API manufacture. The previous process of sitagliptin involved hydrogenation of enamine at high pressure using a rhodium-based chiral catalyst. By developing an engineered transaminase, the enzymatic process was able to convert 200 g/l of prositagliptin in the final product, with e.e. >99.5% and using an immobilized enzyme in the presence of DMSO as a cosolvent [ 2 ]. For all enzymes, the possibility to be immobilized and used in a heterogeneous form brings important industrial and environmental advantages, such as simplified downstream processing or continuous process operations. Here, we present a series of large-scale applications of immobilized enzymes with benefits for the food, chemical, pharmaceutical, cosmetics and medical device industries, some of which have been scarcely reported on previously. In general, all enzymatic reactions can benefit from the immobilization, however, the final choice to use them in immobilized form depends on the economic evaluation of costs associated with their use versus benefits obtained in the process. It can be concluded that the benefits are rather significant, since the use of immobilized enzymes in industry is increasing.

F. Kotz, K. Arnold, W. Bauer et al.

M. Morari, E. Zafiriou

P. Kleindorfer, Germaine H. Saad

J. Klankermayer, Sebastian Wesselbaum, Kassem Beydoun et al.

Miaomiao Zhou, Binghua Yan, J. Wong et al.

A. Ghaly, R. Ananthashankar, M. Alhattab et al.

M. Al‐Ghouti, M. Al-Kaabi, M. Ashfaq et al.

Abstract In oil and gas industry, produced water is considered as the largest waste stream, which contains relatively higher concentration of hydrocarbons, heavy metals and other pollutants. Due to the increase in industrial activities, the generation of produced water has increased all over the world and its treatment for reuse is now important from environmental perspective. Treatment of produced water can be done through various methods including physical (membrane filtration, adsorption etc.), chemical (precipitation, oxidation), and biological (activated sludge, biological aerated filters and others) methods. This paper aims to highlight characteristics of produced water in detail and physical, chemical, and biological techniques used for its treatment. In addition, reuse of produced water for different purposes has been discussed. At the end, few case studies from different countries, related to the treatment and reuse of their produced waters have been included.

Peipei Song, Dan Xu, Jingyuan Yue et al.

With the increasing development of industry and urbanization, heavy metal contaminated sites have become progressively conspicuous, particularly by unreasonable emissions from electroplating, nonferrous metals smelting, mine tailing, etc. In recent years, soil remediation technologies for heavy metal contaminated sites have developed rapidly. New and effective remediation technologies have emerged successively, and more successful practical applications have appeared. Therefore, systematical summarization of the current progress is essential. As a result, in this paper, some mainstream soil remediation technologies for heavy metal contaminated sites, including physical remediation (soil thermal desorption and soil replacement), bioremediation (phytoremediation and microbial remediation), chemical remediation (chemical leaching, chemical stabilization, electrokinetic remediation-permeable reactive barrier, and chemical oxidation/reduction), as well as various combined remediation are comprehensively reviewed. The influencing factors, advantages, disadvantages, remediation mechanism, and practical applications are also deeply discussed. Besides, the corresponding remediation strategies are put forward for the remediation of heavily polluted sites such as the chemical industry, smelting, and tailing areas. Overall, this review will be beneficial for the in-depth understanding and provide references for the reasonable selection and development of soil remediation technology for heavy metal contaminated sites.

Yanli Wang, Stephen H. Bryant, Tiejun Cheng et al.

PubChem's BioAssay database (https://pubchem.ncbi.nlm.nih.gov) has served as a public repository for small-molecule and RNAi screening data since 2004 providing open access of its data content to the community. PubChem accepts data submission from worldwide researchers at academia, industry and government agencies. PubChem also collaborates with other chemical biology database stakeholders with data exchange. With over a decade's development effort, it becomes an important information resource supporting drug discovery and chemical biology research. To facilitate data discovery, PubChem is integrated with all other databases at NCBI. In this work, we provide an update for the PubChem BioAssay database describing several recent development including added sources of research data, redesigned BioAssay record page, new BioAssay classification browser and new features in the Upload system facilitating data sharing.

Antonio Cid-Samamed, Jaruporn Rakmai, J. Mejuto et al.

This review offers a vision of the chemical behaviour of natural ingredients, synthetic drugs and other related compounds complexed using cyclodextrins. The review takes care of different sections related to i) the inclusion complexes formation with cyclodextrins, ii) the determination of the inclusion formation constant, iii) the most used methods to prepare host inclusion in the non-polar cavity of cyclodextrins and iv) the analytical techniques to evidence host inclusion. The review provides different literature that shows the application of cyclodextrins to improve physical, chemical, and biological characteristics of food compounds including solubility, stability and their elimination/masking. Moreover, the review also offers examples of commercial food/supplement products of cyclodextrins to indicate that cyclodextrins can be used to generate biotechnological substances with innovative properties and improve the development of food products.

Zihe Liu, Kai Wang, Yun Chen et al.

J. Banerjee, Ramkrishna Singh, R. Vijayaraghavan et al.

Alexandr Mikyška, Lucie Dolejší, Kateřina Dubnová et al.

The alpha acids content of the 2024 hop crop in the Czech Republic was evaluated using a pre-harvest forecast, a harvest forecast and a reality. The alpha-acids value in the Saaz variety was 2.72% w/w, in the Žatec (2.87% w/w) and Tršice (2.47% w/w) hop growing regions the content was well below the long-term averages, and in the Úštěk region (3.38% w/w) it was in line with the average. In Žatec and Úštěk, the alpha acids of the most widely cultivated hybrid varieties Sládek (7.5 and 6.7% w/w) and Premiant (7.5 and 8.5% w/w) were significantly higher than in Tršice (Sládek 4.8% w/w, Premiant 6.0% w/w). The values of the varieties Saaz Late and Saaz Special were below the average, while Kazbek (6.49% w/w) showed a good tolerance to weather conditions and the alpha acids content slightly above the average. The bitter varieties Agnus, Rubín and Vital with alpha acids content of 11–13% w/w give very stable alpha acids values over the long term, with 2024 corresponding to previous vintages. The harvest forecasts for alpha acids this year were in a very good agreement with reality. The year 2024 was relatively rich in water, but the distribution of rainfall over time was not optimal. Average monthly temperatures during the growing season were 1–2 °C above long-term averages, and the year as a whole was very warm. The Czech Republic's hop harvest (total of 6494 tonnes, yield 1.34 t/ha) was average in 2024. The total alpha acids production from the 2024 harvest was average at 242.5 t. The Saaz hops (82.1 % of the harvested area) accounted for 55% of the total. Bitter hop varieties cope better with adverse weather conditions than aromatic varieties.

Safa Atiyaha, Buthainah AL-Timimi, Ahmed Ali et al.

The fluid catalytic cracking unit converts heavy feedstocks into more valuable gasoline and oil products, representing an essential component in refineries. The variables, including gas oil supply temperature (Tf), gas oil supply flow rate (Ff), and air temperature (Ta), are controlled and manipulated by this unit, which poses a significant challenge due to its complex interactions. To address these complexities, this study investigates the control of riser and regenerator temperatures (TR, TG) in an industrial Universal Oil Products (UOP) fluid catalytic cracking unit using proportional-integral and fuzzy logic controllers. The fuzzy logic controller, with five fuzzy sets generating 25 rules, is implemented through MATLAB simulation. The simulation program is formulated based on the principles of mass and energy balance of the unit. The performance of the controllers, including PI and fuzzy logic controllers, is evaluated and compared by introducing disturbances in the gas oil supply temperature, gas oil supply flow rate, and air temperature. The results show that the fuzzy logic controller outperforms the PI controller, exhibiting a lower integral absolute error. Compared to the PI controller, the fuzzy logic controller demonstrates improved performance, characterized by stable responses and shorter settling times. These findings highlight the effectiveness of the fuzzy logic controller in achieving better control performance for Fluid Catalytic Cracking Units (FCCU).

Liu Chuan-Wen, Liu Min-Hsien, Wang To-Mai et al.

Palygorskite is a magnesium-rich aluminosilicate clay mineral with a unique chain-layered structure. This structure gives palygorskite a large specific surface area and interesting physical properties. Many researchers have investigated the applications of palygorskite in various fields, including heavy metal adsorption, petroleum and chemical industries, building materials, medicine and agriculture. In this study, molecular dynamics simulations were used to explore the heavy metal adsorption ability of palygorskite. The results showed that polyacrylic acid (PAA) had a heavy metal adsorption ability. In terms of the ability of the substrate to adsorb Pb2+, Ni2+ and Cr3+, palygorskite (attapulgite, ATP) was more effective than SiO2 or clay. Based on this study, the same phenomenon reported in the literature was confirmed, and it was demonstrated that molecular dynamics could properly simulate the filtration of heavy metal ions in water using novel materials. Moreover, H+ was found to play an essential role in assisting PAA/ATP in capturing heavy metal ions. Using this method, we were able to observe the details of heavy-ion adsorption.