Molecules

12 pages, 4143 KiB

Open AccessArticle

Efficient Extraction and Separation of Scandium from Scandium-Bearing Solid Waste and Acid by Synergistically Leaching Followed by Solvent Extraction

by Wen Cao, Jinmao Hua, Xi Jin, Minyu He, Yuntao Xin and Weizao Liu

Molecules 2024, 29(19), 4766; https://doi.org/10.3390/molecules29194766 (registering DOI) - 9 Oct 2024

Abstract

The solid waste and waste acid generated during the production of titanium dioxide contain considerable amount of scandium, which are valuable secondary resources. In this study, the titanium dioxide waste acid was used to leach the scandium-containing solid waste, and the leached solution [...] Read more.

The solid waste and waste acid generated during the production of titanium dioxide contain considerable amount of scandium, which are valuable secondary resources. In this study, the titanium dioxide waste acid was used to leach the scandium-containing solid waste, and the leached solution was pretreated for iron removal by reduction-crystallization process. After that, scandium was recovered from the leached solution by using the P204-TBP co-extraction system. The process parameters were investigated systematically. The results showed that iron powder reduction-crystallization for iron removal at molar ratio of Fe:Fe³⁺ = 0.25 was most suitable for subsequent extraction, and the scandium extraction efficiency could reach 100% using 15% P204-5% TBP at 25 °C with A/O = 8. This study provided a novel process for treating scandium-bearing solid waste with scandium-bearing waste acid, showing great potential for industrial application. Full article

(This article belongs to the Special Issue Solid Waste and Fly Ash Chemical Treatment Methods)

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18 pages, 8881 KiB

Open AccessArticle

Investigation of Structural and Spectral Peculiarities of Fusarium sp. Indicator Pigment Bostrycoidin

by Anastasia Povolotckaia, Dmitrii Pankin, Vasiliy Novikov, Evgenii Borisov, Sergey Kuznetsov, Alexey Dorokhov, Anatoly Gulyaev, Elena Zavyalova, Rugiya Alieva, Sergey Akulov, Sergey Belousov and Maksim Moskovskiy

Molecules 2024, 29(19), 4765; https://doi.org/10.3390/molecules29194765 (registering DOI) - 8 Oct 2024

Abstract

Bostrycoidin is one of the pigments produced by the Fusarium genus of fungi. On the one hand, it has significant pharmacological importance, while on the other hand, it serves as a presence marker of Fusarium infection in useful grain crops, fruits, and soils. [...] Read more.

Bostrycoidin is one of the pigments produced by the Fusarium genus of fungi. On the one hand, it has significant pharmacological importance, while on the other hand, it serves as a presence marker of Fusarium infection in useful grain crops, fruits, and soils. In this regard, the structural and optical properties of the bostrycoidin molecule were studied in the framework of density functional theory (DFT). The most stable geometry as well as higher-energy conformers and tautomers were investigated. The lowest-energy tautomer was found to be about 3 kcal/mol higher in energy than the most stable structure, resulting in relatively low population of this state. The obtained conformational rotamers associated with the rotation of the OMe group possess similar energy. The vibrational spectrum was modeled for the most stable conformer, and the most active peaks in the IR absorbance spectrum were assigned. Moreover, the electronic absorption spectrum was simulated within the time-dependent DFT approach. The obtained theoretical spectrum is in good agreement with the experimental data and the theoretically calculated longest-wavelength transition (HOMO–LUMO) was about 498 nm. Full article

(This article belongs to the Section Molecular Structure)

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15 pages, 1073 KiB

Open AccessArticle

Base-Catalyzed Reaction of Isatins and (3-Hydroxyprop-1-yn-1-yl)phosphonates as a Tool for the Synthesis of Spiro-1,3-dioxolane Oxindoles with Anticancer and Anti-Platelet Properties

by Arina V. Murashkina, Andrei V. Bogdanov, Alexandra D. Voloshina, Anna P. Lyubina, Alexandr V. Samorodov, Alexander Y. Mitrofanov, Irina P. Beletskaya, Elena A. Smolyarchuk, Kseniya A. Zavadich, Zulfiya A. Valiullina, Kseniya A. Nazmieva, Vladislav I. Korunas and Irina D. Krylova

Molecules 2024, 29(19), 4764; https://doi.org/10.3390/molecules29194764 - 8 Oct 2024

Abstract

An approach to the synthesis of phosphoryl substituted spiro-1,3-dioxolane oxindoles was developed from the base-catalyzed reaction of various isatins with (3-hydroxyprop-1-yn-1-yl)phosphonates. It was found that various aryl-substituted and N-functionalized isatins with the formation of appropriate products with high yields and stereoselectivity when using [...] Read more.

An approach to the synthesis of phosphoryl substituted spiro-1,3-dioxolane oxindoles was developed from the base-catalyzed reaction of various isatins with (3-hydroxyprop-1-yn-1-yl)phosphonates. It was found that various aryl-substituted and N-functionalized isatins with the formation of appropriate products with high yields and stereoselectivity when using t-BuOLi are able to react. Cytotoxic activity evaluation suggests that the most significant results in relation to the HuTu 80 cell line were shown by N-benzylated spirodioxolanes. 5-Cloro-N-unsubstituted spirooxindoles exhibit antiaggregational activity exceeding the values of acetylsalicylic acid. Full article

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8 pages, 628 KiB

Open AccessArticle

Chiral Sodium Glycerophosphate Catalyst for Enantioselective Michael Reactions of Chalcones

by Giovanni Ghigo, Julia Rivella, Alessio Robiolio Bose and Stefano Dughera

Molecules 2024, 29(19), 4763; https://doi.org/10.3390/molecules29194763 - 8 Oct 2024

Abstract

A chiral sodium glycerophosphate is successfully exploited as a catalyst in the Michael addition of methyl malonate to a number of chalcones. The reactions supplied the target adducts in satisfactory yields and good enantiomeric excesses. A tentative computational study is presented, aiming to [...] Read more.

A chiral sodium glycerophosphate is successfully exploited as a catalyst in the Michael addition of methyl malonate to a number of chalcones. The reactions supplied the target adducts in satisfactory yields and good enantiomeric excesses. A tentative computational study is presented, aiming to understand the reaction mechanism. Full article

(This article belongs to the Special Issue Organometallic Chemistry in Europe)

20 pages, 9140 KiB

Open AccessArticle

Oxidative Catalytic Depolymerization of Lignin into Value-Added Monophenols by Carbon Nanotube-Supported Cu-Based Catalysts

by Chen Tang, Yang Cao, Jie Gao, Gang Luo, Jiajun Fan, James H. Clark and Shicheng Zhang

Molecules 2024, 29(19), 4762; https://doi.org/10.3390/molecules29194762 - 8 Oct 2024

Abstract

Lignin valorisation into chemicals and fuels is of great importance in addressing energy challenges and advancing biorefining in a sustainable manner. In this study, on the basis of the high microwave absorption performance of carbon nanotubes (CNTs), a series of copper-oxide-loaded CNT catalysts [...] Read more.

Lignin valorisation into chemicals and fuels is of great importance in addressing energy challenges and advancing biorefining in a sustainable manner. In this study, on the basis of the high microwave absorption performance of carbon nanotubes (CNTs), a series of copper-oxide-loaded CNT catalysts (CuO/CNT) were developed to facilitate the oxidative depolymerization of lignin under microwave heating. This catalyst can promote the activation of hydrogen peroxide and air, effectively generating a range of reactive oxygen species (ROS). Through the application of electron paramagnetic resonance techniques, these ROS generated under different oxidation conditions were detected to elucidate the oxidation mechanism. The results demonstrate that the ^•OH and O₂^•− play a crucial role in the formation of aldehyde and ketone products through the cleavage of lignin C_β-O and C_α-C_β bonds. We further evaluated the catalytic performance of the CuO/CNT catalysts with three typical lignin feedstocks to determine their applicability for lignin biorefinery. The bio-enzymatic lignin produced a 13.9% monophenol yield at 200 °C for 20 min under microwave heating, which was higher than the 7% yield via hydrothermal heating conversion. The selectivity of G-/H-/S-type products was slightly affected, while lignin substrate had a noticeable effect on the selective production. Overall, this study explored the structural characteristics of CuO/CNT catalysts and their implications for lignin conversion and offered an efficient oxidation approach that holds promise for sustainable biorefining practices. Full article

24 pages, 4672 KiB

Open AccessReview

Comparison of Construction Strategies of Solid Electrolyte Interface (SEI) in Li Battery and Mg Battery—A Review

by Zhongting Wang, Rongrui Deng, Yumei Wang and Fusheng Pan

Molecules 2024, 29(19), 4761; https://doi.org/10.3390/molecules29194761 - 8 Oct 2024

Abstract

The solid electrolyte interface (SEI) plays a critical role in determining the performance, stability, and longevity of batteries. This review comprehensively compares the construction strategies of the SEI in Li and Mg batteries, focusing on the differences and similarities in their formation, composition, [...] Read more.

The solid electrolyte interface (SEI) plays a critical role in determining the performance, stability, and longevity of batteries. This review comprehensively compares the construction strategies of the SEI in Li and Mg batteries, focusing on the differences and similarities in their formation, composition, and functionality. The SEI in Li batteries is well-studied, with established strategies that leverage organic and inorganic components to enhance ion diffusion and mitigate side reactions. In contrast, the development of the SEI in Mg batteries is still in its initial stages, facing significant challenges such as severe passivation and slower ion kinetics due to the divalent nature of magnesium ions. This review highlights various approaches to engineering SEIs in both battery systems, including electrolyte optimization, additives, and surface modifications. Furthermore, it discusses the impact of these strategies on electrochemical performance, cycle life, and safety. The comparison provides insights into the underlying mechanisms, challenges, and future directions for SEI research. Full article

(This article belongs to the Special Issue Advanced Materials for Energy Applications: From Fuels to Batteries and Beyond)

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12 pages, 2946 KiB

Open AccessArticle

Adsorption Property and Morphology Evolution of C Deposited on HCP Co Nanoparticles

by Lili Liu, Yujia Shi, Jiamin Rong, Qiang Wang and Min Zhong

Molecules 2024, 29(19), 4760; https://doi.org/10.3390/molecules29194760 - 8 Oct 2024

Abstract

Despite extensive studies of deposited carbon in Fischer–Tropsch synthesis (FTS), an atomic-level comprehension of the effect of carbon on the morphology of cobalt-based FTS catalysts remains elusive. The adsorption configurations of carbon atoms on different crystal facets of hexagonal close-packed (hcp) Co nanoparticles [...] Read more.

Despite extensive studies of deposited carbon in Fischer–Tropsch synthesis (FTS), an atomic-level comprehension of the effect of carbon on the morphology of cobalt-based FTS catalysts remains elusive. The adsorption configurations of carbon atoms on different crystal facets of hexagonal close-packed (hcp) Co nanoparticles were studied using density functional theory (DFT) calculations to explore the interaction mechanism between C and Co surfaces. The weaker adsorption strength of C atoms on Co(0001), Co(10-10), and Co(11-20) surfaces accounted for lower diffusion energy, leading to the facile formation of C dimers. Electronic property analysis shows that more electrons are transferred from Co surfaces to C atoms on corrugated facets than on flat facets. The deposition of carbon atoms on Co nanoparticles affects surface energy by forming strong Co-C bonds, which causes the system to reach a more energetically favorable morphology with an increased proportion of exposed Co(10-12) and Co(11-20) areas as the carbon content increases slightly. This transformation in morphology implies that C deposition plays a crucial role in determining the facet proportion and stability of exposed Co surfaces, contributing to the optimization of cobalt-based catalysts with improved performance. Full article

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18 pages, 7917 KiB

Open AccessArticle

Dobinin K Displays Antiplasmodial Activity through Disruption of Plasmodium falciparum Mitochondria and Generation of Reactive Oxygen Species

by He Sun, Bo-Chao Liu, Long-Fei He, Chao-Jiang Xiao, Bei Jiang and Lei Shen

Molecules 2024, 29(19), 4759; https://doi.org/10.3390/molecules29194759 - 8 Oct 2024

Abstract

Dobinin K is a novel eudesmane sesquiterpenoids compound isolated from the root of Dobinea delavayi and displays potential antiplasmodial activity in vivo. Here, we evaluate the antiplasmodial activity of dobinin K in vitro and study its acting mechanism. The antiplasmodial activity of dobinin [...] Read more.

Dobinin K is a novel eudesmane sesquiterpenoids compound isolated from the root of Dobinea delavayi and displays potential antiplasmodial activity in vivo. Here, we evaluate the antiplasmodial activity of dobinin K in vitro and study its acting mechanism. The antiplasmodial activity of dobinin K in vitro was evaluated by concentration-, time-dependent, and stage-specific parasite inhibition assay. The potential target of dobinin K on Plasmodium falciparum was predicted by transcriptome analysis. Apoptosis of P. falciparum was detected by Giemsa, Hoechst 33258, and TUNEL staining assay. The reactive oxygen species (ROS) level, oxygen consumption, and mitochondrial membrane potential of P. falciparum were assessed by DCFH-DA, R01, and JC-1 fluorescent dye, respectively. The effect of dobinin K on the mitochondrial electron transport chain (ETC) was investigated by enzyme activity analysis and the binding abilities of dobinin K with different enzymes were learned by molecular docking. Dobinin K inhibited the growth of P. falciparum in a concentration-, time-dependent, and stage-specific manner. The predicted mechanism of dobinin K was related to the redox system of P. falciparum. Dobinin K increased intracellular ROS levels of P. falciparum and induced their apoptosis. After dobinin K treatment, P. falciparum mitochondria lost their function, which was presented as decreased oxygen consumption and depolarization of the membrane potential. Among five dehydrogenases in P. falciparum ETC, dobinin K displayed the best inhibitory power on NDH2 activity. Our findings indicate that the antiplasmodial effect of dobinin K in vitro is mediated by the enhancement of the ROS level in P. falciparum and the disruption of its mitochondrial function. Full article

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22 pages, 4213 KiB

Open AccessArticle

Pitfalls in Photochemical and Photoelectrochemical Reduction of CO₂ to Energy Products

by Tomasz Baran, Domenico Caringella, Angela Dibenedetto and Michele Aresta

Molecules 2024, 29(19), 4758; https://doi.org/10.3390/molecules29194758 - 8 Oct 2024

Abstract

The photochemical and photoelectrochemical reduction of CO₂ is a promising approach for converting carbon dioxide into valuable chemicals (materials) and fuels. A key issue is ensuring the accuracy of experimental results in CO₂ reduction reactions (CO2RRs) because of potential sources of [...] Read more.

The photochemical and photoelectrochemical reduction of CO₂ is a promising approach for converting carbon dioxide into valuable chemicals (materials) and fuels. A key issue is ensuring the accuracy of experimental results in CO₂ reduction reactions (CO2RRs) because of potential sources of false positives. This paper reports the results of investigations on various factors that may contribute to erroneous attribution of reduced-carbon species, including degradation of carbon species contained in photocatalysts, residual contaminants from synthetic procedures, laboratory glassware, environmental exposure, and the operator. The importance of rigorous experimental protocols, including the use of labeled ¹³CO₂ and blank tests, to identify true CO₂ reduction products (CO2RPs) accurately is highlighted. Our experimental data (eventually complemented with or compared to literature data) underline the possible sources of errors and, whenever possible, quantify the false positives with respect to the effective conversion of CO₂ in clean conditions. This paper clarifies that the incidence of false positives is higher in the preliminary phase of photo-material development when CO2RPs are in the range of a few 10s of μg g_cat⁻¹ h⁻¹, reducing its importance when significant conversions of CO₂ are performed reaching 10s of mol g_cat⁻¹ h⁻¹. This paper suggests procedures for improving the reliability and reproducibility of CO2RR experiments, thus validating such technologies. Full article

(This article belongs to the Section Photochemistry)

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16 pages, 6111 KiB

Open AccessArticle

Removal of Pb(II) and Cd(II) from a Monometallic Contaminated Solution by Modified Biochar-Immobilized Bacterial Microspheres

by Zaiquan Li, Xu Xiao, Tao Xu, Shiyu Chu, Hui Wang and Ke Jiang

Molecules 2024, 29(19), 4757; https://doi.org/10.3390/molecules29194757 - 8 Oct 2024

Abstract

Lead (Pb) and cadmium (Cd) are toxic pollutants that are prevalent in wastewater and pose a serious threat to the natural environment. In this study, a new immobilized bacterial microsphere (CYB-SA) was prepared from corn stalk biochar and Klebsiella grimontii by sodium alginate [...] Read more.

Lead (Pb) and cadmium (Cd) are toxic pollutants that are prevalent in wastewater and pose a serious threat to the natural environment. In this study, a new immobilized bacterial microsphere (CYB-SA) was prepared from corn stalk biochar and Klebsiella grimontii by sodium alginate encapsulation and vacuum freeze-drying technology. The removal effect of CYB-SA on Pb(II) and Cd(II) in a monometallic contaminated solution was studied. The results showed that the removal of Pb(II) and Cd(II) by CYB-SA was 99.14% and 83.35% at a dosage of 2.0 g/L and pH = 7, respectively, which was 10.77% and 18.58% higher than that of biochar alone. According to the Langmuir isotherm model, the maximum adsorption capacities of Pb(II) and Cd(II) by CYB-SA at 40 °C were 278.69 mg/g and 71.75 mg/g, respectively. A combination of the kinetic model, the isothermal adsorption model, scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) analyses showed that the main adsorption mechanisms of CYB-SA encompass functional group complexation, ion exchange, electrostatic attraction and physical adsorption. The findings of this study offer practical and theoretical insights into the development of highly efficient adsorbents for heavy metals. Full article

(This article belongs to the Special Issue Advancements in Adsorbent Materials for Water Purification)

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14 pages, 1302 KiB

Open AccessReview

Research Progress on Bioactive Substances of Beets and Their Functions

by Chun Bian, Lanyang Ji, Wei Xu, Shirong Dong and Nan Pan

Molecules 2024, 29(19), 4756; https://doi.org/10.3390/molecules29194756 - 8 Oct 2024

Abstract

As a globally cultivated and economic crop, beets are particularly important in the cane sugar and feed industries. Beet pigments are among the most important natural pigments, while various chemical components in beets display beneficial biological functions. Phenolic substances and betalains, as the [...] Read more.

As a globally cultivated and economic crop, beets are particularly important in the cane sugar and feed industries. Beet pigments are among the most important natural pigments, while various chemical components in beets display beneficial biological functions. Phenolic substances and betalains, as the main bioactive compounds, determine the functional characteristics of beets. This review categorizes the basic types of beets by the chemical composition of bioactive substances in their leaves, stems, and roots and emphatically summarizes the research progress made on the functions of two major substances in different types of beets: phenolic compounds and betalain pigments. This study provides useful insights for the comprehensive and effective application of beets in the health food and pharmaceutical industries. Full article

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33 pages, 20435 KiB

Open AccessArticle

Optimizing NiFe-Modified Graphite for Enhanced Catalytic Performance in Alkaline Water Electrolysis: Influence of Substrate Geometry and Catalyst Loading

by Mateusz Kuczyński, Tomasz Mikołajczyk, Bogusław Pierożyński and Jakub Karczewski

Molecules 2024, 29(19), 4755; https://doi.org/10.3390/molecules29194755 - 8 Oct 2024

Abstract

The oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) are critical processes in water splitting, yet achieving efficient performance with minimal overpotential remains a significant challenge. Although NiFe-based catalysts are widely studied, their performance can be further enhanced by optimizing the [...] Read more.

The oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) are critical processes in water splitting, yet achieving efficient performance with minimal overpotential remains a significant challenge. Although NiFe-based catalysts are widely studied, their performance can be further enhanced by optimizing the interaction between the catalyst and the substrate. Here, we present a detailed investigation of NiFe-modified graphite electrodes, comparing the effects of compressed and expanded graphite substrates on catalytic performance. Our study reveals that substrate geometry plays a pivotal role in catalyst distribution and activity, with expanded graphite facilitating more effective electron transfer and active site utilization. Additionally, we observe that increasing the NiFe loading leads to only modest gains in performance, due to catalyst agglomeration at higher loadings. The optimized NiFe–graphite composites exhibit superior stability and catalytic activity, achieving lower overpotentials and higher current densities, making them promising candidates for sustainable hydrogen production via alkaline electrolysis. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Electrochemistry)

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19 pages, 4801 KiB

Open AccessArticle

Widely Targeted Metabolomics Analysis of the Roots, Stems, Leaves, Flowers, and Fruits of Camellia luteoflora, a Species with an Extremely Small Population

by Weicheng Yang, Fen Liu, Gaoyin Wu, Sheng Liang, Xiaojie Bai, Bangyou Liu, Bingcheng Zhang, Hangdan Chen and Jiao Yang

Molecules 2024, 29(19), 4754; https://doi.org/10.3390/molecules29194754 - 8 Oct 2024

Abstract

Camellia luteoflora is a rare and endangered plant endemic to China. It has high ornamental and potential economic and medicinal value, and is an important germplasm resource of Camellia. To understand the distributions and differences in metabolites from different parts of C. luteoflora [...] Read more.

Camellia luteoflora is a rare and endangered plant endemic to China. It has high ornamental and potential economic and medicinal value, and is an important germplasm resource of Camellia. To understand the distributions and differences in metabolites from different parts of C. luteoflora, in this study, we used liquid chromatography–tandem mass spectrometry (LC–MS/MS) to examine the types and contents of chemical constituents in five organs of C. luteoflora: roots, stems, leaves, flowers, and fruits. The results showed that a total of 815 metabolites were identified in the five organs and were classified into 18 main categories, including terpenoids (17.1%), amino acids (10.4%), flavonoids (10.3%), sugars and alcohols (9.8%), organic acids (9.0%), lipids (7.1%), polyphenols (4.8%), alkaloids (4.8%), etc. A total of 684 differentially expressed metabolites (DEMs) in five organs were obtained and annotated into 217 KEGG metabolic pathways, among which metabolic pathways, ABC transporters, the biosynthesis of cofactors, and the biosynthesis of amino acids were significantly enriched. In DEMs, flowers are rich in flavonoids, polyphenols, organic acids, and steroids; fruits are rich in amino acids, alkaloids, vitamins, and xanthones; stems are rich in lignans; and leaves have the highest relative content of phenylpropanoids, ketoaldehydic acids, quinones, sugars and alcohols, terpenoids, coumarins, lipids, and others; meanwhile, the metabolite content is lower in roots. Among the dominant DEMs, 58 were in roots, including arachidonic acid, lucidone, isoliquiritigenin, etc.; 75 were in flowers, including mannose, shikimic acid, d-gluconic acid, kaempferol, etc.; 45 were in the fruit, including pterostilbene, l-ascorbic acid, riboflavin, etc.; 27 were in the stems, including salicylic acid, d-(-)-quinic acid, mannitol, (-)-catechin gallate, etc.; there was a maximum number of 119 dominant metabolites in the leaves, including oleanolic acid, l-glucose, d-arabitol, eugenol, etc. In sum, the rich chemical composition of C. luteoflora and the significant differences in the relative contents of metabolites in different organs will provide theoretical references for the study of tea, flower tea, edible oil, nutraceuticals, and the medicinal components of C. luteoflora. Full article

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18 pages, 2415 KiB

Open AccessArticle

Effect of Residual Cuts on Deactivation of Hierarchical Y Zeolite-Based Catalysts during Co-Processing of Vacuum Gas Oil (VGO) with Atmospheric Residue (ATR)

by Jayson Fals, Esneyder Puello-Polo and Edgar Márquez

Molecules 2024, 29(19), 4753; https://doi.org/10.3390/molecules29194753 - 8 Oct 2024

Abstract

The influence of residual cuts on the deactivation of hierarchical Y zeolite-based catalysts during the co-processing of vacuum gas oil (VGO) with atmospheric residue (ATR) was investigated. The experiments were conducted in a laboratory-scale MAT-type reactor. The conversion of VGO, ATR, and their [...] Read more.

The influence of residual cuts on the deactivation of hierarchical Y zeolite-based catalysts during the co-processing of vacuum gas oil (VGO) with atmospheric residue (ATR) was investigated. The experiments were conducted in a laboratory-scale MAT-type reactor. The conversion of VGO, ATR, and their 70:30 (mass basis) mixture was examined using two composite catalysts: Cat.Y.0.00 and Cat.Y.0.20. The operating conditions closely resembled those of the commercial catalytic cracking process (550 °C and contact times of 10 to 50 s). When ATR was processed individually, the conversion remained below 50 wt%. However, significant improvements in conversion rates were achieved and catalyst deactivation was mitigated when ATR was co-processed with VGO. Notably, the BET surface area and average mesopore volume were adversely impacted by ATR, which also led to the accumulation of high levels of metals and nitrogen on the spent catalyst, detrimentally affecting its acidic and structural properties. Moreover, substantial coke deposition occurred during ATR cracking. The soluble and insoluble coke analysis revealed H/C ratio values of up to 0.36, indicative of polycondensed coke structures with more than ten aromatic rings. The nature of the coke was confirmed through TPO and FTIR analyses. Interestingly, the CatY.0.20 catalyst exhibited less activity loss, retaining superior acid and structural properties. Co-processing Colombian atmospheric residue with ATR loadings of 30 wt% (higher than the typical 20 wt%) in catalysts formulated with hierarchical zeolites presents a promising alternative for commercial applications. This research opens avenues for optimizing catalytic cracking processes. Full article

(This article belongs to the Special Issue Catalysts: New Materials for Green Chemistry)

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44 pages, 6897 KiB

Open AccessReview

Overview of Liquid Sample Preparation Techniques for Analysis, Using Metal-Organic Frameworks as Sorbents

by Jakub Woźniak, Jakub Nawała, Daniel Dziedzic and Stanisław Popiel

Molecules 2024, 29(19), 4752; https://doi.org/10.3390/molecules29194752 - 8 Oct 2024

Abstract

The preparation of samples for instrumental analysis is the most essential and time-consuming stage of the entire analytical process; it also has the greatest impact on the analysis results. Concentrating the sample, changing its matrix, and removing interferents are often necessary. Techniques for [...] Read more.

The preparation of samples for instrumental analysis is the most essential and time-consuming stage of the entire analytical process; it also has the greatest impact on the analysis results. Concentrating the sample, changing its matrix, and removing interferents are often necessary. Techniques for preparing samples for analysis are constantly being developed and modified to meet new challenges, facilitate work, and enable the determination of analytes in the most comprehensive concentration range possible. This paper focuses on using metal-organic frameworks (MOFs) as sorbents in the most popular techniques for preparing liquid samples for analysis, based on liquid-solid extraction. An increase in interest in MOFs-type materials has been observed for about 20 years, mainly due to their sorption properties, resulting, among others, from the high specific surface area, tunable pore size, and the theoretically wide possibility of their modification. This paper presents certain advantages and disadvantages of the most popular sample preparation techniques based on liquid-solid extraction, the newest trends in the application of MOFs as sorbents in those techniques, and, most importantly, presents the reader with a summary, which a specific technique and MOF for the desired application. To make a tailor-made and well-informed choice as to the extraction technique. Full article

(This article belongs to the Special Issue Current Research Status of Metal-Organic Frameworks and Covalent Organic Frameworks)

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12 pages, 3910 KiB

Open AccessArticle

Fast and Sensitive Determination of Iodide Based on Ternary Chalcogenides Nanoparticles

by Zhitai Wang, Nengtao Wu, Weihao Wang, Yaozheng Hu, Zhijie Luo, Yuhui Zheng and Qianming Wang

Molecules 2024, 29(19), 4751; https://doi.org/10.3390/molecules29194751 - 8 Oct 2024

Abstract

A fluorescent probe based on ternary AgFeS₂ quantum dots has been prepared for the design of ternary chalcogenides. The nanoparticles are synthesized with oleylamine as a stabilizer at a low temperature (particle size in the range of 2 to 3 nm) and [...] Read more.

A fluorescent probe based on ternary AgFeS₂ quantum dots has been prepared for the design of ternary chalcogenides. The nanoparticles are synthesized with oleylamine as a stabilizer at a low temperature (particle size in the range of 2 to 3 nm) and they exhibit an intense blue emission in aqueous media. As for their internal structure, each nanoparticle’s relative stoichiometric ratio (AgFe_1.01S_1.91) is very close to the theoretical value of 1:1:2. Their magnetic properties have been studied with a vibrating sample magnetometer and they have ferromagnetism between 4 K and 298 K (applied magnetic field ranging between −10,000 and 10,000 Oe). In the presence of iodide ions, the emission at 458 nm derived from AgFeS₂ QDs has been observed to give rise to fluorescence quenching. The detection system is based on a static quenching process and morphological change between iodide ions and AgFeS₂, which has a good linear range from 0 to 37.5 μmol/L, with a limit of detection of 0.99 μM. The nanoprobe responds within 30 s for the efficient detection of iodide. Such functional quantum dots will provide a powerful indicator in environmental and bio-sensing applications. Full article

(This article belongs to the Special Issue Exclusive Contributions by the Editorial Board Members (EBMs) of the Inorganic Chemistry Section of Molecules 2024)

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11 pages, 2290 KiB

Open AccessArticle

Enhancing Electrochemical Performance of Si@CNT Anode by Integrating SrTiO₃ Material for High-Capacity Lithium-Ion Batteries

by Nischal Oli, Diana C. Liza Castillo, Brad R. Weiner, Gerardo Morell and Ram S. Katiyar

Molecules 2024, 29(19), 4750; https://doi.org/10.3390/molecules29194750 - 8 Oct 2024

Abstract

Silicon (Si) has attracted worldwide attention for its ultrahigh theoretical storage capacity (4200 mA h g⁻¹), low mass density (2.33 g cm⁻³), low operating potential (0.4 V vs. Li/Li⁺), abundant reserves, environmentally benign nature, and low cost. [...] Read more.

Silicon (Si) has attracted worldwide attention for its ultrahigh theoretical storage capacity (4200 mA h g⁻¹), low mass density (2.33 g cm⁻³), low operating potential (0.4 V vs. Li/Li⁺), abundant reserves, environmentally benign nature, and low cost. It is a promising high-energy-density anode material for next-generation lithium-ion batteries (LIBs), offering a replacement for graphite anodes owing to the escalating energy demands in booming automobile and energy storage applications. Unfortunately, the commercialization of silicon anodes is stringently hindered by large volume expansion during lithiation–delithiation, the unstable and detrimental growth of electrode/electrolyte interface layers, sluggish Li-ion diffusion, poor rate performance, and inherently low ion/electron conductivity. These present major safety challenges lead to quick capacity degradation in LIBs. Herein, we present the synergistic effects of nanostructured silicon and SrTiO₃ (STO) for use as anodes in Li-ion batteries. Si and STO nanoparticles were incorporated into a multiwalled carbon nanotube (CNT) matrix using a planetary ball-milling process. The mechanical stress resulting from the expansion of Si was transferred via the CNT matrix to the STO. We discovered that the introduction of STO can improve the electrochemical performance of Si/CNT nanocomposite anodes. Experimental measurements and electrochemical impedance spectroscopy provide evidence for the enhanced mobility of Li-ions facilitated by STO. Hence, incorporating STO into the Si@CNT anode yields promising results, exhibiting a high initial Coulombic efficiency of approximately 85%, a reversible specific capacity of ~800 mA h g⁻¹ after 100 cycles at 100 mA g⁻¹, and a high-rate capability of 1400 mA g⁻¹ with a capacity of 800 mA h g⁻¹. Interestingly, it exhibits a capacity of 350 mAh g⁻¹ after 1000 lithiation and delithiation cycles at a high rate of 600 mA hg⁻¹. This result unveils and sheds light on the design of a scalable method for manufacturing Si anodes for next-generation LIBs. Full article

(This article belongs to the Special Issue Advanced Nanomaterials for Energy Storage Devices)

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21 pages, 16339 KiB

Open AccessArticle

Optimization of Liquid Fermentation of Acanthopanax senticosus Leaves and Its Non-Targeted Metabolomics Analysis

by Rui Zhang, Xueyan Wang, Jiaojiao Xue, Xiaoli Li, Ying Li, Yi Ding, Yichao Feng, Xueping Zhang, Jianqing Su and Xiuling Chu

Molecules 2024, 29(19), 4749; https://doi.org/10.3390/molecules29194749 - 8 Oct 2024

Abstract

To enhance the nutritional value of Acanthopanax senticosus leaves (AL), a fermentation process was conducted using a probiotic Bacillus mixture, and the changes in chemical constituents and biological activities before and after fermentation were compared. A response surface methodology was employed to optimize [...] Read more.

To enhance the nutritional value of Acanthopanax senticosus leaves (AL), a fermentation process was conducted using a probiotic Bacillus mixture, and the changes in chemical constituents and biological activities before and after fermentation were compared. A response surface methodology was employed to optimize the liquid fermentation conditions of AL based on their influence on polyphenol content. Non-targeted metabolomics analysis was performed using LC-MS/MS to reveal the differing profiles of compounds before and after fermentation. The results indicated that Bacillus subtilis LK and Bacillus amyloliquefaciens M2 significantly influenced polyphenol content during fermentation. The optimal fermentation conditions were determined to be a fermentation time of 54 h, a temperature of 39.6 °C, and an inoculum size of 2.5% (v/v). In comparison to unfermented AL, the total polyphenol and flavonoid contents, as well as the free radical scavenging capacities measured by DPPH and ABTS assays, and the activities of β-glucosidase and endo-glucanase, were significantly increased. The non-targeted metabolomics analysis identified 1348 metabolites, of which 829 were classified as differential metabolites. A correlation analysis between the differential metabolites of polyphenols, flavonoids, and antioxidant activity revealed that 13 differential metabolites were positively correlated with antioxidant activity. Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis of the differential metabolites identified 82 pathways, with two of the top 25 metabolic pathways related to flavonoids. This study explores the potential for enhancing the active ingredients and biological effects of AL through probiotic fermentation using Bacillus strains. Full article

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24 pages, 4776 KiB

Open AccessReview

Artifacts and Anomalies in Raman Spectroscopy: A Review on Origins and Correction Procedures

by Ravi teja Vulchi, Volodymyr Morgunov, Rajendhar Junjuri and Thomas Bocklitz

Molecules 2024, 29(19), 4748; https://doi.org/10.3390/molecules29194748 - 8 Oct 2024

Abstract

Raman spectroscopy, renowned for its unique ability to provide a molecular fingerprint, is an invaluable tool in industry and academic research. However, various constraints often hinder the measurement process, leading to artifacts and anomalies that can significantly affect spectral measurements. This review begins [...] Read more.

Raman spectroscopy, renowned for its unique ability to provide a molecular fingerprint, is an invaluable tool in industry and academic research. However, various constraints often hinder the measurement process, leading to artifacts and anomalies that can significantly affect spectral measurements. This review begins by thoroughly discussing the origins and impacts of these artifacts and anomalies stemming from instrumental, sampling, and sample-related factors. Following this, we present a comprehensive list and categorization of the existing correction procedures, including computational, experimental, and deep learning (DL) approaches. The review concludes by identifying the limitations of current procedures and discussing recent advancements and breakthroughs. This discussion highlights the potential of these advancements and provides a clear direction for future research to enhance correction procedures in Raman spectral analysis. Full article

(This article belongs to the Special Issue Review Papers in Analytical Chemistry)

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