Phenol Yield Research Articles

Unveiling the Catalytic Activity of Nickel(II) Complexes of Pentadentate Ligands in Aromatic Oxidations

Selective oxidation of aromatic substrates to phenols is a challenging goal in synthetic chemistry. Herein, we investigate the catalytic activity of nickel(II) complexes of the type [Ni(L)(CH3CN)](X)2 (1‐4); (X = ClO4‐, BPh4‐, L = N4Py, BnTPEN and, BnImDPEN) supported by pentadentate ligands in the hydroxylation of aromatic substrates to corresponding phenols using H2O2. In benzene oxidation, complex 2 showed a phenol yield of 28% and a turnover number of 560 with 99% selectivity. Also, preferential oxidation of aromatic C‐H bonds over aliphatic C‐H bonds was noted during the oxidation of substituted benzenes. The kinetic isotope effect value (1.01) supported the involvement of nickel‐bound oxygen species in the catalytic cycle rather than hydroxyl radicals. The key source of oxygen in the formed phenol was found to be H2O2 based on the isotope‐labelling experiments using H218O2 and H218O. Although the formation of {[(BnTPEN)Ni(OOH)]+ +NCCH3}+ intermediate was identified upon reacting complex 2 with H2O2, this species did not directly react with benzene to form phenol. Further, DFT studies suggested that the species [(L)NiII(O•)]+ derived from O‐O homolysis of nickel hydroperoxo intermediate reacts with benzene to produce phenol and the presence of a nickel‐based oxidant is the reason behind the excellent selectivity.

Application of perovskite type oxide La x Ce1-x coo3 in lignin depolymerization and mono-phenol preparation.

This study successfully prepared La x Ce1-x CoO3 (x = 0.2, 0.4, 0.6, 0.8, 1) series perovskite oxide catalysts by co precipitation, and found that La0.6Ce0.4CoO3 can significantly improve the yield of bio-oil under specific conditions (lignin to catalyst mass ratio of 1 : 2, reaction temperature of 240 °C, time of 10 hours, using methanol and ethanol as solvents). Furthermore, NH3-TPD, GC-MS, and FTIR analyses revealed the thermal decomposition behavior of key bonding structures such as β-O-4 and C-O-C during the catalytic process, while generating various mono-phenolic products such as guaiacol and 2,6-dimethylphenol. In addition, studies have shown that the physicochemical properties of perovskite type oxide catalysts have a significant impact on the chemical properties of lignin oil. By increasing the acidity of the catalyst, not only can the yield of lignin oil and phenols be improved, but also the yield of carbon can be reduced. More importantly, the catalyst performed well in the test of lignin catalyzed hydrogenation to produce monophenols, significantly improving the conversion rate of lignin and the yield of various monophenols compared to noncatalytic processes.

Green and Innovative Extraction: Phenolic Profiles and Biological Activities of Underutilized Plant Extracts Using Pulsed Electric Fields and Maceration.

Underutilized plant species such as Asteriscus graveolens (Forssk.) Less., Haloxylon scoparium Pomel, and Ruta chalepensis L. have been historically valued in traditional medicine for their potential health benefits. These species present an untapped source of bioactive compounds with significant applications in the food and pharmaceutical industries, including the development of functional foods and additives. Recent advances in food processing have introduced innovative methods, such as pulsed electric fields (PEFs), to enhance the extraction of valuable compounds without compromising their integrity or quality. This study investigates the impact of PEF technology on the recovery of bioactive compounds from these plants, comparing it with conventional maceration (MAC) techniques. Phenolic compound profiles and biological activities, including antioxidant, antimicrobial, anti-inflammatory, and cytotoxic effects, were evaluated. The results demonstrated that for R. chalepensis, PEF extraction achieved comparable phenolic content (58 mg/g) to MAC (72 mg/g). However, MAC generally provided higher phenolic yields for other plants. A. graveolens extracts exhibited significant antitumoral and anti-inflammatory potentials. The antimicrobial results indicated that MAC extracts were more effective against bacterial growth, while PEF extracts outperformed MAC against A. brasiliensis (MIC: 10 mg/mL). Antioxidant potential was observed in both methods, with TBARS IC50 values ranging from 17 to 79.5 µg/mL. While MAC generally yielded superior results, PEF extraction showed great promise as an environmentally sustainable alternative, eliminating the need for organic solvents and aligning with green extraction principles.

Products Distribution and Reaction Kinetics From Co-Pyrolysis of Pinewood and Polypropylene Under Non-Catalytic and Catalytic Reaction Conditions

Abstract Co-pyrolysis technology offers vital pathways for the efficient utilization of plastics and biomass resources to help reduce environmental problems and energy resource issues. The pyrolysis characteristics of pinewood and polypropylene (PP) mixtures were analyzed using thermogravimetric analysis. The results showed a decrease in the first peak of the mixture with an increase in PP in the mixture, while the second peak increased with an increase in PP in the mixture. The addition of a catalyst decreased the DTG peak heights. The reduction in the first peak with different catalysts was in the order: CaO/ZSM-5 > CaO > ZSM-5, while the second peak showed: CaO > CaO/ZSM-5 > ZSM-5. The activation energy, calculated by Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, and Friedman models, revealed that ZSM-5 reduced the activation energy, whereas CaO/ZSM-5 increased the activation energy, as compared to no catalyst case. Increase of co-pyrolysis temperature reduced the yield of aldehydes, ketones, acids, and esters, but increased the yield of hydrocarbons. The addition of CaO reduced the yield of ketones, phenols, esters, and acids, while it increased the yield of alcohols. The addition of ZSM-5 also decreased the yield of ketones, phenols, acids, and hydrocarbons, but increased the yield of furans and alcohols. The addition of CaO/ZSM-5 specifically reduced the yield of aldehydes and alcohols. The results show the important role of the specific catalysts examined on the resulting products distribution for the same reaction condition.

A selective oxidative depolymerization of larch lignin to ethyl vanillate by multifunctional catalysts combining alkaline ionic liquid and polyoxometalates with hydrogen peroxide.

Ethyl vanillate (EV) is an important component of flavors and fragrances and has been widely used in the food, pharmaceutical, and cosmetic industries. The highly selective preparation of EV from lignin, the most abundant monophenolic compound in nature, is a great challenge in the field of lignin depolymerization. In this study, the multi-active catalysts from alkaline ionic liquid and polyoxometalates were constructed, which were characterized by acidity, alkaline and oxidizing ability. They can efficiently cleave the CC and CO bonds of larch lignin in an ethanol/water system at 160°C for 10h with H2O2 as an oxidizing agent. Vanillin and EV were main products with the phenolic yield of 10.14wt% and the selectivity of EV was up to 83.63%. The depolymerization of phenolic and non-phenolic lignin model compounds demonstrated that the cleavage of β-O-4 and Cα-Cβ bonds contributed to the selective preparation of EV in the catalytic system. The catalyst can be recycled up to 4 times with excellent stability and recoverability. This study provides a new approach for the production of EV, which is promising in the high-valued utilization of larch waste.

Optimization of the production of grade A liquid smoke from Patchouli solid residue using a distillation-adsorption process

<p>Patchouli cultivation in Lhokseumawe, Aceh Province, produces a significant amount of biomass, with approximately 96%–98.5% of the raw material ending up as solid residue after the oil distillation process. This waste is often discarded or burned, leading to environmental problems. However, this residue is rich in compounds derived from the breakdown of lignocellulose and can be pyrolyzed to produce liquid smoke. Liquid smoke contains valuable phenols, acids, and carbonyls but may also generate harmful byproducts such as polycyclic aromatic hydrocarbons (PAHs). This study aimed to optimize the production of grade A liquid smoke through purification using a distillation and adsorption process. Pyrolysis of patchouli residue was conducted at 400 ℃ to produce liquid smoke. Furthermore, the raw liquid smoke was purified by distillation and adsorption. The distillation process was conducted at a temperature range (X<sub>1</sub>) of 150–200 ℃ for 30–90 min (X<sub>2</sub>). The weight of activated biochar used during the adsorption process varied between 5 and 15 g (X<sub>3</sub>). The experimental design was carried out using Design Expert version 13. Research findings indicate that the optimal condition for liquid smoke was achieved with the equation Y = 1.26 + 0.53X<sub>1</sub> + 0.0319X<sub>2</sub> + 0.8023X<sub>3</sub> – (4.91X<sub>1</sub>)<sup>2</sup> – (0.0015X<sub>2</sub>)<sup>2</sup> – (0.2147X<sub>3</sub>)<sup>2</sup> – 0. 0644 X<sub>1</sub>X<sub>2</sub> – 0.0327X<sub>1</sub>X<sub>3</sub> + 2.15X<sub>2</sub>X<sub>3</sub>. The best results were obtained at a distillation temperature of 175 ℃, a duration of 90 minutes, and using 13.4 g of activated carbon, which resulted in a high total phenol yield of 8.06%. The produced liquid smoke was classified as grade A, with a yield of 74.33%, a density of 0.9928 g/m³, a viscosity of 1.6203 cP, and a pH of 3.32. This research highlights an eco-friendly solution for valorizing patchouli waste, transforming it into a product with a wide range of applications as a food preservative, flavor enhancer, and medicinal agent.</p>

Foliar Application of Urea and Amino Acids Regulates Growth, Photosynthesis, Pigments, Antioxidant Activity, and the Essential Oil Content and Composition of Basil (Ocimum basilicum L.)

Basil (Ocimum basilicum L.) is a prominent medicinal and aromatic plant, widely recognized for its bioactive compounds and substantial economic value across the pharmaceutical, culinary, and industrial sectors. In light of increasing global demand and environmental challenges, this study explores novel approaches to enhance its sustainable production and improve its quality. Urea is the most common form of nitrogen (N) for foliar application due to its quick absorption, affordability, high solubility, as well as relatively low cost per N unit. Amino acids are an organic form of N and play a role in plant protein structure, stress tolerance, and the biosynthesis of secondary metabolites. This research aimed to evaluate the effects of urea (0, 1, and 2 g L−1) and an amino acid-based biostimulant (AAB) (0, 4, and 8 mg L−1), applied foliarly, on the growth, photosynthesis, pigments, antioxidant activity, and essential oil production of basil (Ocimum basilicum L.). The best results in terms of leaf number, area, and fresh and dry weight were observed with the combination of 2 g L−1 urea and 8 mg L−1 AAB. The growth enhancement due to this treatment may be attributed to stimulatory effects on photosynthesis and N content. Chlorophyll, carotenoids, anthocyanins, photosynthesis, stomatal conductance, total phenols, and total flavonoids increased with urea application up to 1 g L−1. Additionally, AAB application up to 8 mg L−1 increased total chlorophyll, carotenoid, total phenols, and total flavonoids, while photosynthesis and anthocyanin content increased with 4 mg L−1 AAB. Although urea did not significantly affect essential oil content and yield, AAB application increased both. Finally, the combination of 1 g L−1 urea and 8 mg L−1 AAB had the most effective impact on improving content and yield of essential oil, total phenol, flavonoid, anthocyanin, and antioxidant activity, with a relatively high percentage of estragole.

Extraction of Bioactive Compounds from Coffee Husk with Acetone Using Microwave Assisted Extraction Method and Analysis of Phenolic Compounds

Nowadays, the use of coffee husk is limited to animal feed and fertilizer. Therefore, a study was conducted using Robusta coffee husk waste as a raw material for research. The purpose of this study was to determine the effect of several variables and to determine the optimum conditions in the process of extracting bioactive compounds from coffee husk waste. Coffee husk waste will be extracted using the Microwave-Assisted Extraction (MAE) method with acetone solvent, with several variables, namely the ratio of material to solvent, microwave power, and extraction time. Analysis of the identification of phenolic compound content was then also carried out using UV-Vis spectrophotometry. The variables of material ratio, extraction time, and microwave power were proven to be interrelated so that they could produce total phenol at optimum conditions. The optimum conditions for extracting bioactive compounds from coffee husk waste were obtained at a material ratio of 0.04 g/ml; time of 9 minutes; and power of 300 watts, with a total phenol yield of 8.65 GAE/g sample.

Bimetallic nickel‑cobalt sulfide derived from lignin-MOFs hybrid as a high-efficiency heterogeneous catalyst for hydrogenolysis of lignin dimers.

Lignin represents a significant source of aromatic hydrocarbons in the natural world. The production of high-value chemicals from lignin has the great potential to effectively address the issue of fossil energy scarcity. In this study, complex sulfides of nickel‑cobalt bimetallic catalysts were prepared via hydrothermal synthesis and subsequently employed in the catalytic hydrogenolysis of CO bonds present in lignin. A series of complex sulfides Ni3S2/Co3S4-CSn-x-T derived from lignin-MOF (n=0.5, 1, 1.5 and 2; x=2, 4 and 6; T=400, 500, 600 and 700°C), were prepared under different conditions and subsequently employed in the catalytic hydrogenolysis of lignin model compounds. The optimal catalyst Ni3S2/Co3S4-CS1-4-500 exhibited the highest conversion rate of benzyl phenyl ether (BPE) (about 97.3%), and the yields of toluene and phenol produced were 49.5% and 43.6%, respectively with isopropanol as the reaction solvent and no external H2. The introduction of element sulfur in catalysts could effectively inhibit the further hydrogenation of generated aromatic chemicals. The catalysts were well characterized, and the results demonstrated that the catalysts exhibited high catalytic activity with an increased loading of active components. This study provided some novel findings for the construction of biomass-based catalysts and the production lignin-derived aromatic chemicals.

Phenol Concentration in Liquid Smoke Production from Rubberwood by Experiment and Simulation with CFD Modeling

Liquid smoke is produced through condensation resulting from the pyrolysis process of rubberwood, without the presence of oxygen. One of the dominant contents of liquid smoke products is phenol. Therefore, this study aimed to examine the molar concentration of simulated liquid smoke and the comparison between the experimental and simulated molar concentrations. The simulation used Ansys Fluent 19.2, a Computational Fluid Dynamics (CFD) program using the finite volume method in its solution. The several stages in completing Ansys simulation include pre-processing, meshing, processing, and post-processing. The geometry depicted in this study was a 2-dimensional pyrolysis reactor. Assumptions made for the simulation comprised using lignin as raw material, along with specified flowrate, and pyrolysis time. The results showed that based on the reaction mechanism, lignin in the pyrolysis process produced a phenol yield of 4.52%. In the final stage, quantitative data simulation results were obtained in the form of molar concentrations produced from liquid smoke products. The molar concentrations in the simulation during pyrolysis for 1, 2, 3, 4, and 5 hours were 0.00183512, 0.0017854, 0.00170856, 0.0017628, and 0.00166788 kmol/m3, respectively. The experimental molar concentration results also showed the same pattern as the simulation data. At 4 hours of pyrolysis, the molar concentration of phenol increased, resulting in liquid smoke with the best quality. A comparison of liquid smoke molar concentration for the simulation and experiment indicated a minimal difference of 0.005%.

Effect of arbuscular mycorrhiza and rhizobium on physiology and yield of peanut under drought conditions.

Drought is the one primary issue limiting peanut growth and productivity. The study aimed to investigate the effects of arbuscular mycorrhizal fungi (AMF), rhizobium (Rhi), and their combinations on phenolic content, proline content, growth, and yield of peanut under different soil water regimes. The pot experiments were carried out for two growing seasons under greenhouse conditions and designed based on a 2×3 factorial in randomized complete block design (RCBD) with four replications. Factor A comprised two soil water regimes: field capacity (FC) and 1/3 available soil water (1/3 AW), whereas factor B included three different types of microorganisms: (i) uninoculated control, (ii) arbuscular mycorrhiza (AMF), and (iii) a combination of AMF and rhizobium (Rhi) inoculations. Data were collected for growth, proline content, phenolic content, yield, and yield components. Drought stress significantly reduced in relative water content, leaf area, biomass, yield, and yield components of peanut, whereas leaf phenolic content was increased under drought stress. Higher pod dry weight was achieved under FC conditions (28.87g plant-1), and it was reduced to 16.06g plant-1 under 1/3 FC. Interestingly, AMF+Rhi synergistically increased the leaf area compared with non-incubated peanut under 1/3 FC conditions. AMF-inoculated peanut tended to increase biomass, while the combination of AMF+Rhi tended to have higher yield components compared with uninoculated control, especially for the weight of 100 seeds.

Visible-Light Induced C-H Oxygenation of Hydrocarbons Using Chlorine Dioxide as a Photoredox Catalyst

Photocatalytic oxygenation of benzene occurs in an oxygen-saturated acetonitrile solution containing acridnium ion or quinolinium ion derivatives as a photoredox catalyst, benzene and water under light irradiation to yield phenol and hydrogen peroxide selectively. The benzene radical cation, which is formed by photoinduced one-electron oxidation of benzene with the excited state of catalyst, reacts with H2O to yield phenol.Photocatalytic oxygenation of benzene with oxygen occurs under photoirradiation of an acetonitrile solution of 3-cyano-1-methylquinolinium perchlorate (QuCN+ClO4 –) in an oxygen-saturated acetonitrile (MeCN) containing benzene and H2O with a xenon lamp (500 W) attached with a color-cut glass filter. The selectivity of formation of phenol was 98% with 16% quantum yield after 1 h irradiation, and then 51% of phenol yield after 5 h irradiation. The photocatalytic turnover number (TON) was 7.5. This is the first example of photocatalytic oxygenation of benzene to phenol in a homogeneous system. A preparative gram-scale photocatalytic reaction with benzene (2.3 g, 29 mmol) and QuCN+ (210 mg, 0.8 mmol) in MeCN (200 mL) for 48 h was also examined to afford phenol (1.1 g, 12 mmol) as 41% yield.

Selective Photocatalytic Benzene Oxidation Using Iron‐Carbon Nitride Fragments Functionalized with Cyamelurate‐Like Groups

AbstractCarbon nitrides have emerged as promising supports for catalytically active metals in various chemical reactions. Among these, the selective oxidation of benzene to phenol stands out as particularly challenging within the chemical industry due to its traditionally low yields and complex reaction pathways. In our current investigation, we have focused on the synthesis of ionic carbon nitride fragments via a straightforward alkaline hydrolysis method. These fragments demonstrate a remarkable ability to stabilize iron cations within the carbon nitride structure (Frag‐Fe), resulting in a highly efficient photocatalyst for benzene oxidation. Employing hydrogen peroxide as the oxidant in a single‐step reaction, we achieved an impressive 47 % yield of phenol using Frag‐Fe at 12 hours, with negligible production of CO2 as a byproduct. This compelling outcome underscores the effectiveness of our alkaline synthesis approach in generating carbon nitride‐based photocatalysts with exceptional activity for C−H oxidation reactions. Our findings not only contribute to the advancement of carbon nitride‐based catalysis, but also hold significant promise for the development of more sustainable and efficient chemical processes in the future.

Chemical constituents and biological activities of endophytic fungi from Fagopyrum dibotrys.

Fagopyrum dibotrys is an important wild food and feed germplasm resource. It has high nutritional and medicinal value and is rich in natural products, including flavonoids, phenolic acids, coumarins, and alkaloids. Endophytic fungi in F. dibotrys have emerged as valuable sources of natural products. However, studies on the biological activity and chemical composition of these endophytic fungi remain limited. In this paper, a new method to obtain natural active ingredients by fermentation of endophytic fungi from medicinal plants was proposed. Then the antioxidant and pathogenic activities of the endophytic fungi extracts were determined in vitro. In addition, secondary metabolites produced by endophytic fungi with medicinal activity were analyzed by high performance liquid chromatography-tandem mass spectrometry (LC-MS). Among the 95 endophytic fungal strains in F. dibotrys, four strains with high phenol yields were selected by reaction: Alternaria alstroemeriae (J2), Fusarium oxysporum (J15), Colletotrichum karsti (J74), and Colletotrichum boninense (J61). Compared with those of various extracts, the ethyl acetate fractions of A. alstroemeriae (J2), F. oxysporum (J15), and C. boninense (J61) exhibited superior antioxidant and antibacterial properties. The results indicated that the fungal extract was an excellent natural antioxidant and might be a potential antibacterial agent. The DPPH free radical clearance of A. alstroemeriae was 94.96 ± 0.004%. These findings indicated that A.alstroemeriae had strong antioxidant activity. In addition, the extract of A.alstroemeriae had good antibacterial activity against Escherichia coli and Staphylococcus aureus, with MICs of 0.5 and 0.05 mg/mL, respectively. The chemical constituents of the ethyl acetate extract from A. alstroemeriae were further analyzed by liquid chromatography-mass spectrometry (LC-MS). We noted that A. alstroemeriae can create a variety of medicinal substances that have high value in medicine, such as caffeic acid (884.75 ng/mL), 3-phenyllactic acid (240.72 ng/mL) and norlichexanthone (74.36ng/mL). In summary, many valuable active substances and medicinal substances can be obtained through the study of endophytic fungi of F. dibotrys.

In vitro strategy to enhance the production of bioactive polyphenols and caffeoylputrescine in the hairy roots of Physalis peruviana L.

The Rhizobium rhizogene-transformed root culture from Physalis peruviana L. (P. peruviana) may be a promising and novel source of valuable phenolics, including caffeoylputrescine (CP), which is known for antioxidant, antidiabetic, insect-resistant, disease-resistant, and neuroprotective properties. In this study, to improve the production efficiency of phytochemical components in P. peruviana hairy root cultures, we optimized various culture conditions, including the inoculum size, liquid volume, culture media type, carbon source, sucrose concentration, initial pH, and application of elicitors, to enhance the total phenolic content and CP yield in these hairy root cultures. The findings indicate that the use of sucrose as carbon source resulted in the highest biomass (13.28 g DW/L), total phenolic content (6.26 mg/g), and CP yield (2.40 mg/L). The White medium excelled in enhancing the total phenolic content (9.35 mg/g), whereas the B5 medium was most effective for the biomass (13.38 g DW/L) and CP yield (6.30 mg/L). A sucrose concentration of 5% was best for the biomass (18.40 g DW/L), whereas a sucrose concentration of 4% was ideal for the CP yield. Optimal culture conditions were as follows: an inoculum size of 0.5 g/100 mL, a liquid volume of 100 mL in a 250-mL flask, B5 medium, 4% sucrose, and a pH of 5.5. Among the tested elicitors, methyl jasmonate (MeJA) at 100 µM significantly increased the biomass (21.3 g/L), total phenolic content (23.34 mg/g), and CP yield (141.10 mg/L), which represent 0.96-, 2.12-, and 13.04-fold increases, respectively, over the control after 8 days. The optimized HR culture of P. peruviana provides a promising system to enhance the production of CP for pharmaceutical applications.

In Situ Preparation of Highly Active and Selective Fe‐MOF/V–C3N4 for Photocatalytic Hydroxylation of Benzene to Phenol

AbstractThe selective photocatalytic oxidation of benzene to phenol under mild conditions is of great significance for the next‐generation phenol industry. In order to improve the efficiency of the phenol production process, a heterojunction catalyst based on Fe‐MOF/V–C3N4 was synthesized by solvothermal method. Compared with Fe‐MOF and C3N4, the photogenerated charge separation rate of this composite catalyst was significantly enhanced, and the photogenerated electron‐hole complexation was significantly weakened.Under the optimal conditions, the yield and selectivity of phenol were 18.75 % and 96 % respectively, and the photocatalytic activity remained high after four reaction cycles. The improved strategy for this catalyst will provide some new insights for the development of more efficient photocatalysts for the direct hydroxylation of benzene to phenol.

An Innovative Biphasic Reaction System for Highly Selective Benzene Hydroxylation based on Photocatalytic Polymer Composites

AbstractThe hydroxylation of benzene to phenol in presence of hydrogen peroxide was performed using a new biphasic system consisting of a solid phase, a photocatalytically active monolithic polymer composite, immersed in an aqueous phase in which H2O2 is dissolved. In detail, ZnO photocatalytic particles were embedded into the hydrophobic syndiotactic polystyrene (sPS) polymer. Zinc oxide nanostructures (ZnO NSs) were synthesized by an electrochemical procedure. The surface morphology and structure of ZnO nanoparticles and ZnO‐sPS monolithic aerogel composite (ZnO/sPS) were investigated by scanning electron microscopy, X‐ray diffraction and X‐ray photoelectron spectroscopy analysis. Photocatalytic results evidenced that, under UV irradiation, both ZnO NSs and biphasic system water‐photocatalytic composites had a high benzene oxidative property but with very low phenol yield (<2 %) at pH=7. To enhance the phenol selective formation, the pH of the aqueous solution surrounding the photocatalytic polymer composite was modified. A phenol yield of about 94 % and benzene conversion higher than 99 % was obtained in alkaline conditions (pH=11).

Heteropolyacids promoted NiMo/MOF catalyst for catalytic oxidation of lignin dimers in oxygen atmosphere

Heteropolyacids promoted NiMo/MOF catalyst for catalytic oxidation of lignin dimers in oxygen atmosphere

Multi-functional PGPR Serratia liquefaciens confers enhanced resistance to lead stress and bacterial blight in soybean (Glycine max L.)

Multi-functional PGPR Serratia liquefaciens confers enhanced resistance to lead stress and bacterial blight in soybean (Glycine max L.)

Recycling Valuable Phenol from Polycarbonate Plastic Waste Via Direct Depolymerization and Csp2-Csp3 Bond Cleavage Under Mild Conditions.

Upcycling plastic waste into commodity chemicals is recognized as an environmentally benign solution and beneficial for the sustained growth of humanity. Nevertheless, transition metal-free catalysts and energy-efficient conditions pose significant challenges due to the robust mechanical properties of plastics. Here, a strategy for selective production of phenol by upcycling polycarbonate waste via direct depolymerization and Csp2-Csp3 bond cleavage in an aqueous medium under mild conditions is reported. The commercial zeolites efficiently catalyze the depolymerization, Csp2-Csp3 bond hydrolysis, and direct Csp2-Csp3 bond scission at Cα of PC. Among all evaluated zeolites, HY (Si/Al=15) showed excellent catalytic performance, attributed to the ~75 % yield of phenol and ~15 % of acetone. The approach also employs different municipal waste PC for upcycling. Studies reveal that HY (15) exhibits high catalytic efficiency and phenol yield due to its optimum acid sites and textual properties. A scale-up experiment demonstrated that 3.1 g of phenol was produced from 5.0 g of PC, and the mass balance was 90 %. A combination of control experiments, NMR analysis, and DFT studies proposed the reaction pathway. Our findings present a sustainable avenue for upcycling PC waste and offer a new way to produce phenol, contributing to the advancement of a circular economy.