This report discloses a mild and efficient O-acetylation using easily accessible TMSOAc as a novel acetyl reagent and O-trimethylsilylation using HMDS for various alcohols catalyzed by tunable Brønsted acidic ionic liquids (TBAILs). Imidazolium-based TBAILs were prepared by a two-step atom-economic reaction and acidities measured by using UV-visible spectroscopy. Both protections for alcohols were accomplished at room temperature with good to excellent yields, while the products and TBAILs were separated by simple work-up for O-silylation and column chromatography for O-acetylation. Notably, with the simple post-process, TBAILs catalyst in this solvent free method easily recovered and recycled several times without significant degradation. Full article

The objective of our study was to prepare Y-, USY- and ZSM-5-based catalysts by hydrothermal synthesis, followed by copper active-phase deposition by either conventional ion-exchange or ultrasonic irradiation. The resulting materials were characterized by XRD, BET, SEM, TEM, Raman, UV-Vis, monitoring ammonia and nitrogen oxide sorption by FT-IR and Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). XRD data confirmed the purity and structure of the Y/USY or ZSM-5 zeolites. The nitrogen and ammonia sorption results indicated that the materials were highly porous and acidic. The metallic active phase was found in the form of cations in ion-exchanged zeolites and in the form of nanoparticle metal oxides in sonochemically prepared catalysts. The latter showed full activity and high stability in the SCR deNO_x reaction. The faujasite-based catalysts were fully active at 200–400 °C, whereas the ZSM-5-based catalysts reached 100% activity at 400–500 °C. Our in situ DRIFTS experiments revealed that Cu–O(NO) and Cu–NH₃ were intermediates, also indicating the role of Brønsted sites in the formation of NH₄NO₃. Furthermore, the results from our experimental in situ spectroscopic studies were compared with DFT models. Overall, our findings suggest two possible mechanisms for the deNO_x reaction, depending on the method of catalyst preparation (i.e., conventional ion-exchange vs. ultrasonic irradiation). Full article

Over the last few decades, bio-based polymers have attracted considerable attention from both academic and industrial fields regarding the minimization of the environmental impact arising from the excessive use of petrochemically-based polymeric materials. In this context, poly(ethylene vanillate) (PEV), an alipharomatic polyester prepared from 4-(2-hydroxyethoxy)-3-methoxybenzoic acid, a monomer originating from lignin-derived vanillic acid, has shown promising thermal and mechanical properties. Herein, the effects of three different catalysts, namely titanium butoxide (TBT), titanium isopropoxide (TIS), and antimony trioxide (Sb₂O₃), on the synthesis of PEV via a two-stage melt polycondensation method are investigated. The progress of the reaction is assessed using various complementary techniques, such as intrinsic viscosity measurement (IV), end group analysis (AV), nuclear magnetic resonance spectroscopy (NMR), Fourier-transformed infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). The thermal stability of the produced polyesters is studied by evolved gas analysis mass spectrometry (EGA-MS). Moreover, as the discoloration in polymers affects their applications, color measurement is performed here. Finally, theoretical kinetic studies are carried out to rationalize the experimental observations. Full article

Magnesium oxide nanoparticles (MgO-NPs) were synthesized using the fungal strain Aspergillus terreus S1 to overcome the disadvantages of chemical and physical methods. The factors affecting the biosynthesis process were optimized as follows: concentration of Mg(NO₃)₂·6H₂O precursor (3 mM), contact time (36 min), pH (8), and incubation temperature (35 °C). The characterization of biosynthesized MgO-NPs was accomplished using UV-vis spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy—energy dispersive X-ray (SEM-EDX), X-ray diffraction (XRD), and dynamic light scattering (DLS). Data confirmed the successful formation of crystallographic, spherical, well-dispersed MgO-NPs with a size range of 8.0–38.0 nm at a maximum surface plasmon resonance of 280 nm. The biological activities of biosynthesized MgO-NPs including antimicrobial activity, biotreatment of tanning effluent, and chromium ion removal were investigated. The highest growth inhibition of pathogenic Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans was achieved at 200 μg mL^–1 of MgO-NPs. The biosynthesized MgO-NPs exhibited high efficacy to decolorize the tanning effluent (96.8 ± 1.7% after 150 min at 1.0 µg mL^–1) and greatly decrease chemical parameters including total suspended solids (TSS), total dissolved solids (TDS), biological oxygen demand (BOD), chemical oxygen demand (COD), and conductivity with percentages of 98.04, 98.3, 89.1, 97.2, and 97.7%, respectively. Further, the biosynthesized MgO-NPs showed a strong potential to remove chromium ions from the tanning effluent, from 835.3 mg L^–1 to 21.0 mg L^–1, with a removal percentage of 97.5%. Full article

The strong catalytic performance, eco-friendly reaction systems, and selectivity of enzyme-based biocatalysts are extremely interesting. Immobilization has been shown to be a good way to improve enzyme stability and recyclability. Chitosan-incorporated metal oxides, among other support matrices, are an intriguing class of support matrices for the immobilization of various enzymes. Herein, the cross-linked chitosan/zinc oxide nanocomposite (CS/ZnO) was synthesized and further improved by adding iron oxide (Fe₂O₃) nanoparticles. The final cross-linked CS/ZnO/Fe₂O₃ nanocomposite was used as an immobilized support for catalase and is characterized by SEM, EDS, and FTIR. The nanocomposite CS/ZnO/Fe₂O₃ enhanced the biocompatibility and immobilized system properties. CS/ZnO/Fe₂O₃ achieved a higher immobilization yield (84.32%) than CS/ZnO (37%). After 10 repeated cycles, the remaining immobilized catalase activity of CS/ZnO and CS/ZnO/Fe₂O₃ was 14% and 45%, respectively. After 60 days of storage at 4 °C, the remaining activity of immobilized enzyme onto CS/ZnO and CS/ZnO/Fe₂O₃ was found to be 32% and 47% of its initial activity. The optimum temperature was noticed to be broad at 25–30 °C for the immobilized enzyme and 25 °C for the free enzyme. Compared with the free enzyme optimum pH (7.0), the optimum pH for the immobilized enzyme was 7.5. The K_m and V_max values for the free and immobilized enzyme on CS/ZnO, and the immobilized enzyme on CS/ZnO/Fe₂O₃, were found to be 91.28, 225.17, and 221.59 mM, and 10.45, 15.87, and 19.92 µmole ml⁻¹, respectively. Catalase immobilization on CS/ZnO and CS/ZnO/Fe₂O₃ offers better stability than free catalase due to the enzyme’s half-life. The half-life of immobilized catalase on CS/ZnO/Fe₂O₃ was between 31.5 and 693.2 min. Full article

Carbonic anhydrase (CA) is an enzyme of high interest due to its high implications relative to the medical and environmental sectors. In the current paper, an enzyme assay for the determination of CA activity is proposed and it is characterized by its simplicity and high practicability. It permits the straightforward comparison of CAs performance in physiological conditions. The methodology and the theoretical background of the evaluation method are explained in detail. Moreover, the presumed advantages over alternative assays are discussed. The assay has proven to be particularly useful for the screening of CA activity with respect to their application in CO₂, capturing processes for further utilization or storage. Full article

Fast pyrolysis bio-oil is very difficult to be used because of its acidity, instability, high degree of unsaturation, etc. Processes for property upgrading are necessary and required. In this study, three kinds of Raney Ni catalysts were prepared and used to investigate two-step esterification–hydrogenation (TEH) to upgrade the light fraction of bio-oil. The results show that the first step in esterification markedly decreased the content of active compounds such as acids and ketones and aldehydes and increased the content of alcohols and esters (from 10.53% to 47.55%), which improved the bio-oil stability and was favorable for the following hydrogenation reaction. The second step of TEH (hydrogenation) further improved the quality of the bio-oil over Raney Ni and metal-modified Raney Ni catalysts at 140 °C. In particular, the Mo-RN catalyst displayed the best hydrogenation effect, with only 5.44% of acid content, and the stable component content reached 90.16%. This may be attributed to the higher hydrogenation activity from Raney Ni combined with acid MoO_x species and the thermal stability of the catalyst. Moreover, the obtained upgraded bio-oil mixture could be used as a solvent for raw bio-oil’s esterification. Therefore, it has the potential to reduce methanol solvent usage and energy consumption for solvent separation during the two-step treatment of raw bio-oil in this context. Compared with the OHE (one-step esterification-hydrogenation) process, THE showed a better performance for raw bio-oil upgrading with higher alcohols and stable compounds, which is more favorable for the saturation and stability of bio-oil’s complex components step by step. Full article

A new series of xylyl-linked bis-benzimidazolium salts were efficiently prepared using a simple preparation method from bis-benzimidazolium precursors featuring highly tunable linkers and wingtips. A highly efficient Suzuki–Miyaura cross-coupling reaction of aryl chlorides within the range of 0.5–2.0 mol% Pd-catalyst loading was observed. Also, di-ortho-substituted biaryl synthesis was achieved. Full article

Protein extraction techniques are absolutely required for the research of biological catalysts. The present study compared four universal protein extraction methodologies (ammonium sulfate precipitation, TCA/acetone precipitation, and two commercial kits) to provide practical information on protein extraction in order to discover a novel lipase in agricultural products. Yields of protein extraction from 24 domestic agricultural products and their specific activities were evaluated and compared with each other. TCA/acetone precipitation showed a relatively higher extraction yield (on average, 3.41 ± 1.08 mg protein/0.1 g sample) in crude protein extraction, whereas the Pierce™ Plant Total Protein Extraction Kit showed the highest specific lipase activity on average in both spectrophotometric (266.61 ± 235.78 μU/mg protein) and fluorometric (41.52 ± 32.63 μU/mg protein) assays. Our results suggest that commercial kits for the rapid extraction of soluble functional proteins would be a better choice than conventional precipitation techniques to perform the high-throughput screening of enzyme activity from plant sources. Finally, several agricultural products such as cordyceps, pepper, bracken, and hemp, all of which exhibited an excellent specific lipase activity, were proposed as promising candidates for a source of novel lipases. Full article

Rice is the second most extensively consumed food ingredient, and its by-products in the paddy field include rice husk and straw. Rice husk ash, resulting from rice husk burning, is considered an environment menace, inducing negative effects on the area in which it is disposed of. In this study, rice husk was applied as a silicate source to obtain mesoporous silica material. Characterization techniques confirmed the well-ordered mesophase and resemblance of mesoporous silica resulting from rice husk ash with one obtained from conventional silica sources. The mesoporous silica material was further used as catalyst support. The resulting catalysts were used for rhodamine 110 oxidation, proving high potential for oxidizing hazardous organic compounds, such as dyes from water, resulting in environmentally harmless products. Full article

Enzyme immobilization has become a key strategy to improve the stability and recycling of biocatalysts, resulting in greener and more cost-efficient processes. The design of the immobilized catalysts is often focused only on the immobilization strategy, the binding chemistry between the enzyme and the support, while less attention has been paid to the physico-chemical properties of material supports. Selecting the best carrier for a specific application may greatly influence the performance of the biocatalytic reaction. Herein, we present a comparative study between the two most used material supports for protein immobilization, agarose and methacrylate. Hydrophilic agarose microbeads ensure higher retained enzymatic activity and better catalyst performance when hydrophobic compounds are involved in the biotransformation. Due to the high stickiness, lipophilic molecules represent a major limitation for methacrylate carriers. O₂-dependent reactions, in contrast, must be carried out by immobilized enzymes on methacrylate supports due to the low mechanical stability of agarose under dehydration conditions. All these parameters were tested with a special focus on continuous-flow applications. Full article

In recent years, a great deal of attention has been paid by the scientific community to improving the efficiency of photosynthetic carbon assimilation, plant growth and biomass production in order to achieve a higher crop productivity. Therefore, the primary carboxylase enzyme of the photosynthetic process Rubisco has received considerable attention focused on many aspects of the enzyme function including protein structure, protein engineering and assembly, enzyme activation and kinetics. Based on its fundamental role in carbon assimilation Rubisco is also targeted by the CO₂-fertilization effect, which is the increased rate of photosynthesis due to increasing atmospheric CO₂-concentration. The aim of this review is to provide a framework, as complete as possible, of the mechanism of the RuBP carboxylation/hydration reaction including description of chemical events occurring at the enzyme “activating” and “catalytic” sites (which involve Broensted acid-base reactions) and the functioning of the complex molecular machine. Important research results achieved over the last few years providing substantial advancement in understanding the enzyme functioning will be discussed. Full article

Biodiesel is a promising alternative to fossil fuels and mainly produced from oils/fat through the (trans)esterification process. To enhance the reaction efficiency and simplify the production process, various catalysts have been introduced for biodiesel synthesis. Recently, the use of bio-derived catalysts has attracted more interest due to their high catalytic activity and ecofriendly properties. These catalysts include alkali catalysts, acid catalysts, and enzymes (biocatalysts), which are (bio)synthesized from various natural sources. This review summarizes the latest findings on these bio-derived catalysts, as well as their source and catalytic activity. The advantages and disadvantages of these catalysts are also discussed. These bio-based catalysts show a promising future and can be further used as a renewable catalyst for sustainable biodiesel production. Full article

Depleting petroleum resources coupled with the environmental consequences of fossil fuel combustion have led to the search for renewable alternatives, such as biodiesel. In this study, sunflower (Helianthus annus), mustard (Brassica compestres) and pearl millet (Pennisetum americanum) seed oils were converted into biodiesel (fatty acid methyl esters) by acid-, base- and lipase-catalyzed transesterification, and the resultant fuel properties were determined. The methyl esters displayed superior iodine values (102–139), low densities, and a high cetane number (CN). The highest yield of biodiesel was obtained from mustard seed oil, which provided cloud (CP) and pour (PP) points of −3.5 and 5 °C, respectively, and a CN of 53. The sunflower seed oil methyl esters had a density of 0.81–0.86 kg/L at 16 °C, CP of 2 °C, PP of −8 °C, and a CN of 47. The pearl millet seed oil methyl esters yielded a density 0.87–0.89 kg/L, CP and PP of 4 °C and −5 °C, respectively, and a CN of 46. The major fatty acids identified in the sunflower, mustard, and pearl millet seed oils were linolenic (49.2%), oleic acid (82.2%), and linoleic acid (73.9%), respectively. The present study reports biodiesel with ideal values of CP and PP, to extend the use of biodiesel at the commercial level. Full article