Step-by-Step Modulation of Crystalline Features and Exciton Kinetics for 19.2% Efficiency Ortho-Xylene Processed Organic Solar Cells

With plenty of popular and effective ternary organic solar cells (OSCs) construction strategies proposed and applied, its power conversion efficiencies (PCEs) have come to a new level of over 19% in single-junction devices. However, previous studies are heavily based in chloroform (CF) leaving behind substantial knowledge deficiencies in understanding the influence of solvent choice when introducing a third component. Herein, we present a case where a newly designed asymmetric small molecular acceptor using fluoro-methoxylated end-group modification strategy, named BTP-BO-3FO with enlarged bandgap, brings different morphological evolution and performance improvement effect on host system PM6:BTP-eC9, processed by CF and ortho-xylene (o-XY). With detailed analyses supported by a series of experiments, the best PCE of 19.24% for green solvent-processed OSCs is found to be a fruit of finely tuned crystalline ordering and general aggregation motif, which furthermore nourishes a favorable charge generation and recombination behavior. Likewise, over 19% PCE can be achieved by replacing spin-coating with blade coating for active layer deposition. This work focuses on understanding the commonly met yet frequently ignored issues when building ternary blends to demonstrate cutting-edge device performance, hence, will be instructive to other ternary OSC works in the future.

Critical conditions for liquid chromatography of statistical polyolefins: Evaluation of diene distribution in EPDM terpolymers

Liquid chromatography at critical conditions is of interest as it may unravel molecular information on macromolecular structures not accessible by any other analytical techniques. Yet so far, such conditions have never been experimentally established for copolymers, where a particular need for such information exists. Toward this goal, critical conditions for statistical ethylene propylene copolymers were identified. In the first approach the composition of the binary mobile phase was varied at a constant temperature, and secondly by modulating the adsorption-desorption temperature at constant mobile phase composition. Solvents for both methods were identified by using a novel approach that combines structure retention relationships with Hansen Solubility Parameters. As a result, for the first time, the heterogeneity of an ethylene propylene diene terpolymer sample with regard to the pendant double bond of the diene could be determined. The novel chromatographic approach was validated by measuring the composition of fractions taken over the chromatographic run offline by nuclear magnetic resonance. In summary, this work gave the first experimental evidence for the existence of critical conditions for polyolefin random copolymers, as postulated by Brun. This novel chromatographic approach holds immense potential to engineer complex polymers towards future applications by making use of the now-accessible molecular information.

Energy, exergy, economic, environment, exergo-environment based assessment of amine-based hybrid solvents for natural gas sweetening

Natural gas is the cleanest form of fossil fuel that needs to be purified from CO₂ and H₂S to diminish harmful emissions and provide feasible processing. The conventional chemical and physical solvents used for this purpose have many drawbacks, including corrosion, solvent loss, high energy requirement, and the formation of toxic compounds, which ultimately disrupt the process and affect the environment. Hybrid solvents have lately been researched to cater to these liabilities and enhance process economics. This study screened eight solvents based on CO₂ selectivity viscosity, absorption enthalpy, corrosivity, working capacity, specific heat, and vapor pressure. From the screened solvents, ten cases of hybrid solvents are simulated and optimized on Aspen HYSYS®. Furthermore, 5Es (Energy, Exergy, Economic, Environmental, and Exergy-environmental) analyses were performed on optimized cases, and results were compared with the base case, MEA (30 wt%). The hybrid blend of Sulfolane and MDEA with weight percentages of 6% and 24%, respectively, showed the highest energy savings of 20% concerning the base case. In addition, it offered 93% savings in exergy destruction and 17.26% in the total operating cost of the process. It is also promising to the environment due to reduced entropy sent to the ecosystem and controlled CO₂ emissions. Therefore, the blend of Sulfolane and MDEA is proposed to Supersede the conventional solvent MEA for the natural gas sweetening process.

Predicting process design spaces for spray drying amorphous solid dispersions

Amorphous solid dispersions (ASDs) are commonly manufactured using spray-drying processes. The product quality can be decisively influenced by the choice of process parameters. Following the quality-by-design approach, the identification of the spray-drying process design space is thus an integral task in drug product development. Aiming a solvent-free and homogeneous ASD, API crystallization and amorphous phase separation needs to be avoided during drying. This publication provides a predictive approach for determining spray-drying process conditions via considering thermodynamic driving forces for solvent drying as well as ASD-specific API/polymer/solvent interactions and glass transitions. The ternary API/polymer/solvent phase behavior was calculated using the Perturbed-Chain Statistical Associating Theory (PC-SAFT) and combined with mass and energy balances to find appropriate spray-drying conditions. A process design space was identified for the ASDs of ritonavir and naproxen with either poly(vinylpyrrolidone) or poly(vinylpyrrolidone-co-vinylacetate) spray dried from the solvents acetone, dichloromethane, or ethanol.

Solvent influence on the phase behavior and glass transition of Amorphous Solid Dispersions

Understanding the long-term stability of amorphous solid dispersions (ASDs) is important for their successful approval for market. ASD stability does not only depend on the interplay between the active pharmaceutical ingredient (API) and the polymer in the final formulation but may already be disadvantageously influenced by process steps during the production (e.g. selection of inappropriate solvent for spray drying). Residual solvent can affect the API solubility in the polymer, molecular mobility (by influencing the glass-transition temperature) and induce liquid-liquid phase separation. Enhanced mobility in the ASD due to residual solvent can promote recrystallization in ASDs. The removal of residual solvent can be expensive, time-consuming, and usually requires secondary drying procedures to fulfil the regulatory requirements. The aim of this work is to predict the API solubility in polymer-solvent mixtures, solvent influence on the glass transition, and the occurrence of liquid-liquid phase separation of solvent-loaded ASDs using the thermodynamic model PC-SAFT and to experimentally validate these predictions. ASDs containing the APIs ritonavir or naproxen and the polymers poly(vinylpyrrolidone), poly (vinylpyrrolidone-co-vinyl acetate), or hydroxypropyl methylcellulose acetate succinate were spray-dried using the solvents acetone, ethanol, and dichloromethane. API solubility, sorption behavior, liquid-liquid phase separation and glass transition in the ternary API/polymer/solvent mixtures were predicted based on the binary phase behavior between API/solvent, API/polymer, and polymer/solvent and successfully validated experimentally using dynamic vapor sorption (DVS), and Raman spectroscopy. Thus, the presented methodology allows for an in-silico selection of appropriate solvent systems for solvent-based ASD preparation based on a limited amount of experimental data for binary systems only.

What is the best ethanol-water ratio for the extraction of antioxidants from rosemary? Impact of the solvent on yield, composition, and activity of the extracts

Extracts rich in antioxidants, such as rosemary extracts, are currently obtained by extraction of the plant material using hydro-alcoholic mixtures with high ethanol content. As this ratio is generally chosen by default and scarcely optimized, we intended to investigate the impact of the hydro-alcoholic composition on extract characteristics such as extraction yield, composition profile in selected compounds, and antioxidant/reducing activity such as Folin-Ciocalteu, DPPH, and ORAC. A theoretical determination of rosmarinic (RA) and carnosic (CA) acid solubilities in ethanol:water mixtures was also performed using COSMO-RS and was confronted to experiments. While the best solubilizing solvent (100% ethanol) was also the best extracting solvent for CA, it was not the case with RA since pure ethanol appeared as a poor solvent compared to 30% ethanol which was optimal. Finally, the best antioxidant activities were obtained with 30% ethanol.

Express Analysis of Microalgal Secondary Carotenoids by TLC and UV-Vis Spectroscopy

We elucidate the peculiarities of express analysis of secondary carotenoids from microalgae and their preliminary identification using TLC and UV-Vis spectroscopy with emphasis on biotechnologically significant producers of the value-added pigment astaxanthin. Advantages and limitations of the method are described to underline the value of TLC as a potential companion method to mainstream separation techniques such as HPLC. Special attention is paid to common errors and pitfalls of the method and possible work-arounds, as well as to overall strategy of the analysis, sample preparation, and material selection.

Isolation of sutherlandins A, B, C and D from Sutherlandia frutescens (L.) R. Br. by counter-current chromatography using spiral tubing support rotors

Spiral countercurrent-chromatography has great potential for improving the capacity and efficiency of purification of secondary metabolites, and here we describe applications useful for the isolation of flavonoids from the widely used South African medicinal plant, Sutherlandia frutescens (L.) R. Br. In the spiral tubing support rotor, STS-4 for high-speed counter-current chromatography, several polar butanol aqueous solvent systems were selected using a logK plot, and the novel flavonol glycosides (sutherlandins A-D) were well separated by the optimized solvent system (ethyl acetate:n-butanol:acetic acid:water; 5:1:0.3:6 by vol.). The yield of purified flavonoids from 0.9g extract varied from 8.6mg to 54mg of the sutherlandins for a total of 85.3mg. The same extract was fractionated in the new STS-12 rotor of the same outside dimensions but with more radial channels forming 12 loops of the tubing instead of 4. The rotor holds more layers and increased length of tubing. From 0.9g extract the STS-12 rotor yielded more recovery of 110.4mg total with amounts varying from 11.2mg to 64mg of the sutherlandins and apparent increased separation efficiency as noted by less volume of each fraction peak. Thus from 1-g amounts of extract, good recovery of the flavonoids was achieved in the butanol aqueous solvent system.

Techno-economic assessment of hybrid extraction and distillation processes for furfural production from lignocellulosic biomass

BACKGROUND

Lignocellulosic biomass is one of the most promising alternatives for replacing mineral resources to overcome global warming, which has become the most important environmental issue in recent years. Furfural was listed by the National Renewable Energy Laboratory as one of the top 30 potential chemicals arising from biomass. However, the current production of furfural is energy intensive and uses inefficient technology. Thus, a hybrid purification process that combines extraction and distillation to produce furfural from lignocellulosic biomass was considered and investigated in detail to improve the process efficiency. This effective hybrid process depends on the extracting solvent, which was selected based on a comprehensive procedure that ranged from solvent screening to complete process design.

RESULTS

Various solvents were first evaluated in terms of their extraction ability. Then, the most promising solvents were selected to study the separation feasibility. Eventually, processes that used the three best solvents (toluene, benzene, and butyl chloride) were designed and optimized in detail using Aspen Plus. Sustainability analysis was performed to evaluate these processes in terms of their energy requirements, total annual costs (TAC), and carbon dioxide (CO₂) emissions. The results showed that butyl chloride was the most suitable solvent for the hybrid furfural process because it could save 44.7% of the TAC while reducing the CO₂ emissions by 45.5% compared to the toluene process. In comparison with the traditional purification process using distillation, this suggested hybrid extraction/distillation process can save up to 19.2% of the TAC and reduce 58.3% total annual CO₂ emissions. Furthermore, a sensitivity analysis of the feed composition and its effect on the performance of the proposed hybrid system was conducted.

CONCLUSIONS

Butyl chloride was found to be the most suitable solvent for the hybrid extraction/distillation process of furfural production. The proposed hybrid sequence was more favorable than the traditional distillation process when the methanol fraction of the feed stream was <3% and more benefit could be obtained when that fraction decreased.