Phenol Molecules Research Articles

Constructing Organic-Inorganic Woven Hybrid Membrane for Highly-Selective Catalytic Conversion of Lignin-based Phenolic Molecule to Value-added Products

Addressing the global need for sustainable chemical processes, this study introduces an innovative Woven Hybrid Membrane (WHM) specifically designed for the efficient oxidation of vanillyl alcohol (VAA) to vanillin (VLN). This transformation is crucial for converting lignocellulosic biomass into valuable chemical products, aligning with sustainable development goals. Utilizing a novel catalytic system that combines 2,2,6,6-tetramethylpiperidine 1-oxyl (TMP) and copper on a unique mesh-like structure, the WHM enhances both the economic and environmental viability of the process. This design not only overcomes the limitations of powdered catalysts, which are challenging to recover and reuse, but also promotes high catalytic efficiency and selectivity. By employing oxygen as the oxidant, our system maintains near 100% selectivity for VLN, demonstrating high conversion rates across multiple cycles without significant degradation in performance. Advanced analytical techniques, including electrochemical analysis and Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS), were used to explore the catalyst’s functionality and the reaction mechanism. The results confirm the stability and effectiveness of the WHM, showcasing its potential as a reusable, highly efficient, and environmentally friendly catalyst. This research represents a significant step forward in the field of sustainable industrial chemistry, offering a robust solution for the bio-refinery industry's push towards greener processes.

Characterization of two bacterial tyrosinases from the halophilic bacterium Hahella sp. CCB MM4 relevant for phenolic compounds oxidation in wetlands.

Tyrosinases (TYRs) are type-3 copper proteins that are widely distributed in nature. They can hydroxylate and oxidize phenolic molecules and are mostly known for producing melanins that confer protection against photo induced damage. TYRs are also thought to play an important role in the 'latch mechanism', where high concentrations of phenolic compounds inhibit oxidative decomposition of organic biomass and subsequent CO2 release, especially relevant in wetland environments. In the present study, we describe two TYRs, HcTyr1 and HcTyr2, from halophilic bacterium Hahella sp. CCB MM4 previously isolated at Matang mangrove forest in Perak, Malaysia. The structure of HcTyr1 was determined by X-ray crystallography at a resolution of 1.9 Å and represents an uncharacterized group of prokaryotic TYRs as demonstrated by a sequence similarity network analysis. The genes encoding the enzymes were cloned, expressed, purified and thoroughly characterized by biochemical methods. HcTyr1 was able to self-cleave its lid-domain (LID) in a protease independent manner, whereas the LID of HcTyr2 was essential for activity and stability. Both enzymes showed variable activity in the presence of different metals, surfactants and NaCl, and were able to oxidize lignin constituents. The high salinity tolerance of HcTyr1 indicates that the enzyme can be an efficient catalyst in the habitat of the host.

Enhanced Photocatalytic Degradation Performance by Micropore-Confined Charge Transfer in Hydrogen-Bonded Organic Framework-Like Cocrystals.

Carrier utilization in organic photocatalytic materials is unsatisfactory due to the large exciton binding energy and short exciton diffusion length. Both donor-acceptor (D-A) strategies and porous designs are promising approaches to improve carrier utilization in photocatalysts. However, a more efficient way is to shorten the distance of exciton migration to the catalyst surface by the charge transfer (CT) process. Herein, hydrogen-bonded organic framework-like cocrystal (NDI-Cor HOF-cocrystal) is prepared with novel structures serving as a proof of concept for the approach, using N, N'-bis (5-isophthalate) naphthalimide (NDI-COOH) as the porous framework and acceptor, and Coronene (Cor) as the donor unit. CT and porous engineering are integrated through cocrystal strategy. Under light irradiation, photogenerated excitons transfer and dissociate from the inner surface of the micropores on a hundred-picosecond time scale, where efficient radical transformation and further redox reactions with adsorbed phenol molecules occur. NDI-Cor HOF-cocrystal photocatalytic degradation of phenol is 15 times higher than that of original HOFs, and achieves near 90% deep mineralization of phenol. Significantly, this work has designed novel HOF-cocrystal and also provides new modification strategies for high performance organic photocatalysts.

Design of New Partially Bio-Based Polyguanamines for the Reversible Adsorption of Phenolic Molecules from Olive Mill Wastes

Design of New Partially Bio-Based Polyguanamines for the Reversible Adsorption of Phenolic Molecules from Olive Mill Wastes

Ligand‐Directed Synthesis of a Self‐Organized Chloro‐Bridged Cubic Pd(II) Cage Showing Selective Encapsulation of Phenols

AbstractThe synthesis and guest recognition properties of a neutral Pd24‐cubic cage, [{Pd3(NiPr)3PO}8(μ2‐Cl)24] 1 are reported. The formation of the cubical assembly takes place by an exclusive one‐pot ligand‐assisted pathway directed by an oximido linker. The initial coordination of the oximido ligand pre‐organizes the [Pd3(NiPr)3PO]3+ polyhedral building units into a tetrameric intermediate, which then transforms into an oximido‐tethered tetrahedral assembly and to the cubical cage 1 in the presence of chloride ions. In the absence of the directing oximido linker, no cage formation was observed, and the Pd6‐precursor was found to undergo self‐condensation, giving rise to a new pentameric polyhedral cluster, [Pd5{(NiPr)3PO}2(OAc)2(OH)2] 2. The central cavity of the cube has been probed for guest encapsulation studies, which shows a high binding with phenolic guest molecules with association constants of the order of 104–105 M−1. The favorable formation of host–guest complexes was attributed to the strong hydrogen bonding interactions between the host and guest functional groups.

Ligand-Directed Synthesis of a Self-Organized Chloro-Bridged Cubic Pd(II) Cage Showing Selective Encapsulation of Phenols.

The synthesis and guest recognition properties of a neutral Pd24-cubic cage, [{Pd3(NiPr)3PO}8(μ2-Cl)24] 1 are reported. The formation of the cubical assembly takes place by an exclusive one-pot ligand-assisted pathway directed by an oximido linker. The initial coordination of the oximido ligand pre-organizes the [Pd3(NiPr)3PO]3+ polyhedral building units into a tetrameric intermediate, which then transforms into an oximido-tethered tetrahedral assembly and to the cubical cage 1 in the presence of chloride ions. In the absence of the directing oximido linker, no cage formation was observed, and the Pd6-precursor was found to undergo self-condensation, giving rise to a new pentameric polyhedral cluster, [Pd5{(NiPr)3PO}2(OAc)2(OH)2] 2. The central cavity of the cube has been probed for guest encapsulation studies, which shows a high binding with phenolic guest molecules with association constants of the order of 104-105 M-1. The favorable formation of host-guest complexes was attributed to the strong hydrogen bonding interactions between the host and guest functional groups.

Versatile and durable polyvinyl alcohol/alginate/gelatin/quaternary ammonium chitosan/Fe3O4 particles hybrid hydrogel beads: adsorption capabilities for cleaning pollutants

A novel hybrid hydrogel bead (HHBFe) composed of polyvinyl alcohol/sodium alginate/gelatin/quaternary ammonium chitosan (PVA/GA/SA/QCS) and Fe3O4 magnetic nanoparticles was developed through green cross-linking of Ca2+ and tannic acid (TA) combined freeze-thaw method. HHBFe exhibited a good spherical shape, porosity, magnetic properties, and excellent mechanical properties and durability. The adsorption capacity of HHB and HHBFe towards methyl orange (MO), tetracycline (Tc), and Cr (VI) was systematically studied and compared. Results revealed similar adsorption capacities for MO and Cr (VI) between HHB and HHBFe, while the presence of Fe3O4 significantly enhanced Tc adsorption, indicating the versatile adsorption functions of HHBFe. Adsorption kinetic followed the pseudo-second-order model, with external diffusion and intra-particle diffusion controlling process. The adsorption data were consistent with the Langmuir isothermal adsorption model, indicating predominantly monolayer adsorption of pollutants by beads. Notably, the beads exhibited easily regenerated, maintaining 60 % of initial adsorption capacity after 5 cycles, particularly for Tc and Cr (VI). The good adsorption performance of HHBFe can be attributed to the strong interaction between their multi-functional groups including phenolic hydroxyl groups, carboxyl groups, amino groups, etc., and pollutant molecules. The multifunctional HHBFe beads prepared in this study and the results obtained with three completely different types of pollutants provide reliability support for their use in different wastewater treatment fields and even in the field of drug carriers.

Computational insights into the deoxygenation reaction of biomass-derived phenolic compounds over Ni2P (001) catalysts

This research sets the scene for understanding the interaction of phenolic molecules (i.e., phenol, o-cresol, m-cresol, and p-cresol) with Ni2P catalyst surface and how their hydrodeoxygenation reaction progresses over the surface. The hydrodeoxygenation process is responsible for removing the oxygen content from the pyrolysis oil compounds, particularly through direct deoxygenation route. Ni2P, which is one of the most common transition metal phosphides, serves as a candidate surface of this study. Two main investigations were carried out including the optimization of (1) adsorption configuration of the phenolic compounds and the (2) net charge distribution between the surface and the adsorbate. According to the adsorption energy studies, the horizontal configuration of the o-cresol molecule on the Ni2P(001) hollow site presented the most optimized and stable configuration with the least negative adsorption energy (−0.26 eV), resulting in the most negative net charge density at −0.286 |e|, as determined by the Bader charge analysis. Upon adsorption on Ni2P(001) surface, o-cresol undergoes significant charge redistribution, where the oxygen atom (-OH group) exhibits a net charge of −1.3443 |e|, indicating electron transfer to the surface. The catalytic pathway proceeded with deoxygenation followed by ring hydrogenation to produce toluene (C7H8), such that C–O bond dissociation has a reaction energy of −0.715 eV, while C–H bond formation step had a reaction energy of 0.011 eV.

Phytochemical profile, bioactivity, and molecular docking studies of natural edible mushrooms grown in Tokat and Sivas provinces of Turkey.

Mushrooms have been essential to the human diet because they contain balanced chemical components and some biologically active substances. In this work, we investigated the phenolics, essential oils, metal contents, antioxidant, antibacterial, DNA protective, and enzyme inhibition activities for Clitocybe geotropa, Ramaria aurea, Rhizopogon luteolus (RL), Russula delica (RD), Verpa bohemica, and Marasmius oreades mushrooms. Results exhibited a higher content for citric and succinic acids in all tested kinds. Further, we detected a high content of cis-9-oleic acid, linoleate, and cis-11-eicosanoate. All mushroom species contain a significant percentage of both Cu and Zn. Moreover, RL and RD recorded the highest phenolic and flavonoid contents. Furthermore, all samples showed standard to good antioxidant activity, and the same is true for the antibacterial and DNA protective activities. Enzyme inhibition activity was generally high and significantly higher against the urease than the thiourea. We applied molecular docking between the highest phenolic molecules with the urease to determine the mushroom extracts' high inhibition mechanism. In conclusion, all mushroom species revealed a variety in chemical content that is probably related to their multi-bioactivity.

The evaluation of the interaction of baicalein (5,6,7-trihydroxyflavone) with human IgG and a glioblastoma multiforme (GBM) cell line

Baicalein, a nutritional phenolic bioactive small molecule present in the roots of Scutellaria baicalensis and Scutellaria lateriflora, shows promising therapeutic effects against a wide range of cancer cells. However, its potential binding with blood carrier proteins and its anticancer mechanisms have not been well investigated. In this study, the interaction between baicalein and immunoglobulin G (IgG) was analyzed by analyzing intrinsic fluorescence, ellipticity changes, as well as molecular docking. The anticancer effects of baicalein against a glioblastoma multiforme (GBM) cell line, U87MG, and one normal immortalized human astrocytes were assessed by MTT, real-time PCR, caspase assay, and western blot. It was shown that the fluorescence quenching mechanism of human IgG by baicalein was based on a static quenching, where one binding site was responsible for the formation of baicalein-IgG complex derived by the formation of hydrogen bonds and van der Waals forces. A molecular docking study indicated that tyrosine residues (Tyr 91 and Tyr 98) were mostly involved in the binding site of baicalein to IgG. The cellular assay demonstrated that baicalein induced U87MG cell line death with an IC50 concentration of 73.19 µM, whereas normal astrocytes depicted over 82.94% portion of viability at 100 µM baicalein. The Bax mRNA overexpression, Bcl-2 mRNA downexpression, as well as the elevation of caspase-9 and caspase-3 activities confirmed that baicalein could effectively trigger the apoptosis of U87MG cells. Moreover, it was explored that baicalein downregulated the expression of the Axl/STAT3 signaling pathway in the U87MG cells, which is responsible for cellular proliferation and growth. In conclusion, these data may provide useful information regarding the pharmaceutical application of baicalein.

Expression of Concern: Adsorptions of phenol molecules by graphene-based nanostructures, modified with nitrogen and bromine, from petroleum wastewater using molecular dynamics simulation

Expression of Concern: Adsorptions of phenol molecules by graphene-based nanostructures, modified with nitrogen and bromine, from petroleum wastewater using molecular dynamics simulation

Ferulic acid-arabinoxylan conjugates: Synthesis, characterization and applications in antibacterial film formation

A novel antibacterial film based on arabinoxylan (AX) was prepared by introducing ferulic acid (FA) to AX through a laccase-catalyzed procedure. The ferulic acid-arabinoxylan conjugates (FA-AX conjugates) have been characterized. Results showed that FA was successfully grafted onto the AX chains by covalent linkages, likely through nucleophilic addition between O-Ph in the phenolic hydroxyl group of FA, or through Michael addition via O-quinone intermediates. FA-AX conjugates showed improved crystallinity, thermal stability, and rheological properties, as well as a distinct surface morphology, compared with those of native AX. Moreover, FA-AX conjugates exhibited enhanced antibacterial ability against Staphylococcus aureus, Escherichia coli, Shewanella sp., and Pseudomonas sp. Mechanistic studies revealed that the enhanced antibacterial ability was due to the penetration of bacterial membrane by the phenolic molecule and the steric effect of FA-AX conjugates. The study demonstrates that the laccase-induced grafting method was effective in producing FA-AX conjugates; we have demonstrated its antibacterial ability and great potential in prolonging the shelf life of fresh seafood products.

Unlocking the potential of Allium dictyoprasum C.A. Meyer ex Kunth: quantum chemical insights into radical scavenging, chemical composition, phenolic content, and antimicrobial activity

ABSTRACT Allium dictyoprasum C.A. Meyer ex Kunth (A. dictyoprasum) underwent comprehensive analysis, encompassing quantum chemical computations to assess its radical scavenging potential, chemical and elemental composition, total phenolic content, and antimicrobial activity. Experimental and theoretical investigations focused on elucidating the radical scavenging properties of polyhydroxy phenolic compounds present in the plant. Quantum chemical calculations were employed to evaluate the antioxidants employed to evaluate selected polyhydroxy phenolic molecules including flavonoids, hydrocinnamic acid derivatives, and hydroxybenzoic acid derivatives from natural sources. Thermochemical parameters of these compounds were calculated by the B3LYP/6–311 G++(d,p) level in both gas and solvent phases to elucidate the radical scavenging mechanism including hydrogen atom transfer (HAT), single electron transfer followed by proton transfer (SET-PT) and sequential proton loss electron transfer (SPLET). Analysis of A. dictyoprasum extracts obtained via various extraction methods revealed the presence of several major compounds, including dimethyl trisulfide, 3,5-Dihydroxy-6-methyl-2,3-dihydro-4 H-pyran-4-one, 2-Methoxy-4-vinylphenol, Dimethyl phthalate, Methyl palmitate, Methyl oleate, Methyl stearate, (9Z)-9-Octadecenamide. Notably, Malic acid and Quinic acid were identified as major compounds, with concentrations of 43.31 and 17.47 mg kg−1 extract, respectively, based on LC-MS/MS analysis. The total phenolic content of the extract was measured as 17.83 mg gallic acid/mL, while its free radical scavenging activity was 80.89% per mg/mL. Elemental analysis revealed significant levels of Mg, K, Na, Fe, and P, with minor concentrations of elements such as Ti, Tl, B, and Be. Furthermore, A. dictyoprasum exhibited notable antibacterial activity against various bacteria strains, surpassing the efficacy of some commercial antibiotics.

Evaluation of the anti-inflammatory, antinociceptive, and antipyretic potential of ethanolic extract of Aristida depressa Retz through in vitro, in vivo, and in silico models.

Uncontrolled inflammation is a crucial factor in the development of many diseases. Anti-inflammatory molecules based on natural sources are being actively studied, among which Aristida depressa Retz (Ar.dp) has been traditionally used as a paste to heal inflammation. The present study aimed to evaluate the anti-inflammatory, analgesic, and antipyretic potential of an ethanolic extract of A. depressa through a battery of in vivo and in vitro models. The ethanolic extract of A. depressa was prepared by maceration and chemically characterized using high-performance liquid chromatography, which revealed the presence of quercetin, vanillic acid, chlorogenic acid, p-coumaric acid, m-coumaric acid, ferulic acid, cinnamic acid, and sinapic acid; its antioxidant capacity was then screened with the DPPH in vitro assay, which indicated moderate scavenging capacity. A protein denaturation assay was next performed to evaluate the in vitro anti-inflammatory potential of Ar.dp, which showed significant inhibition (44.44%) compared to the standard drug (diclofenac sodium), with 89.19% inhibition at a concentration of 1mg/mL. The in vivo safety profile of Ar.dp was evaluated in accordance with the OECD-425 acute toxicity guidelines and found to be safe up to 5g/kg. The in vivo anti-inflammatory potentials of Ar.dp were evaluated at three different doses (125, 250, and 500mg/kg) in acute (carrageenan-induced edema: 84.60%, histamine-induced paw edema: 84%), sub-chronic (cotton-pellet-induced granuloma: 57.54%), and chronic (complete-Freund's-adjuvant-induced arthritis: 82.2%) models. Our results showed that Ar.dp had significant (p < 0.05) anti-inflammatory effects over diclofenac sodium in the acute and chronic models. Histopathology studies indicated reduced infiltration of paw tissues with inflammatory cells in Ar.dp-treated animals. Similarly, Ar.dp showed significant (p < 0.05) analgesic (yeast-induced-pyrexia model: 23.53%) and antipyretic (acetic-acid-induced writhing model: 51%) effects in a time-dependent manner. In silico studies on the interactions of COX-1 and COX-2 with the eight ligands mentioned earlier confirmed the inhibition of enzymes responsible for inflammation and fever. Based on the findings of the present study, it is concluded that Ar.dp has anti-inflammatory, analgesic, and antipyretic properties that are likely linked to its pharmacologically active phenolic bioactive molecules.

Lecithin-based micellar extraction of bioactive from pomegranate peel and its application in Indian flat bread (chapati) as a bioactive emulsifier

Micellar extraction is a sustainable, eco-friendly, and cost-efficient method for extracting and recovering phenolic and flavonoid molecules from pomegranate peel. This technique traps bioactive molecules in micelles formed by a surfactant above cloud point temperature (CPT). The influence of process variables such as lecithin concentration (8–16%), pH (3−6), temperature (40–60 °C), and NaCl concentration (8–16%) on extraction was examined and then optimized numerically. For micellar separation, lecithin and salt content were the most significant (p < 0.05). The optimal variables to maximize bioactive recovery were 13.11% (w/v) lecithin concentration, 4.13 pH at 50.88 °C, and 13.89% (w/v) NaCl concentration. 88.21% of total polyphenols (TPC) and 82.64% of total flavonoids (TFC) were recovered at optimal conditions. The yields of TPC, TFC, punicalagin (PC), ellagic acid (EAC), and total hydrolyzable tannins (THTC) were 163.36 mg gallic acid equivalent/g, 24.71 mg quercetin equivalent/g, 27.29 mg/g, 8.97 mg/g, and 112.36 mg tannic acid equivalent/g of pomegranate peel, respectively. The extract exhibited good antioxidant capacity (55.18% DPPH and 39.25% ABTS). Using liquid chromatography mass spectroscopy, total 14 additional hydrolyzable tannins compounds were identified. The changes in functional groups and thermal properties of the micellar pomegranate peel extract enriched lecithin (MPEL) and pomegranate peel were effectively correlated by fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. MPEL was employed to prepare chapatis. The staling, textural, and bioactive properties of MPEL-enriched chapatis were significantly improved as compared to the control chapatis. However, the color and sensory attributes of chapatis developed with and without lecithin were similar. Additionally, MPEL also controlled staling and microbial growth (AMC: aerobic mesophilic count and YMC: yeast and mold count) along with the retention of the texture of chapatis during the storage of 5 days at 5 and 25 °C.

Separating and identifying multiple structural isomers of 3-hydroxy-3-(3′-hydroxyphenyl)propanoic acid (3,3′-HPHPA)

3-hydroxy-3-(3′-hydroxyphenyl)propanoic acid (CID: 102959) (3,3’-HPHPA) is one of several phenolic molecules that are generated by a process involving gut microbiota and have been implicated in autism and schizophrenia. The structural isomers of 3,3′-HPHPA have been challenging to separate chromatographically. Accordingly, their distribution across brain and other compartments in humans and experimental animals remains poorly characterized. We describe a modified liquid chromatography mass spectroscopy method for the detection and separation of seven commercially available structural isomers of 3,3′-HPHPA. We used the method to screen different compartments in the mouse and demonstrate its utility in identifying multiple structural isomers and conjugates of 3,3′-HPHPA in biological matrices. Characterizing the diversity and complexity of this family of structural isomers will advance studies of their bioactivity and clinical relevance.

Enhanced peroxymonosulfate activation by δ-MnO2 nanocatalyst enriched with oxygen vacancies for phenolic pollutants polymerization

Heterogeneous advanced oxidation processes technology holds great potential for the removal of toxic phenolic molecules in water, but is currently challenged by overuse of oxidation agents and undesirable carbon emissions during the mineralization process. The present work demonstrates that with an oxygen-vacancy-rich Fe doped δ-phase MnO2 (δ-MnO2) as the nanocatalyst, the phenol (PhOH) could be removed with high selectivity as well as effective conversion into non-toxic phenolic polymers via a non-radical electron transfer route, instead of complete mineralization by common radical attacking route. Oxygen vacancies in δ-MnO2 were enriched by Fe doping, which greatly improved the activation of peroxymonosulfate (PMS) by extending the length of the O-O bond in PMS. A 6.68-fold enhancement of the removal rate of PhOH was achieved by Fe doping δ-MnO2, compared to the pristine δ-MnO2. Moreover, the consumption of PMS could be reduced by up to 95.08 %, and the carbon emissions were also reduced by up 99.13 % during the polymerization process. The present study manifests that rationally designing a non-radical route offers significant potential for the cost-effective use of oxidation agents as well as reducing carbon emissions, presenting a superior approach for the target of achieving carbon neutrality in environmental remediation.

Modeling the Kinetics, Equilibrium and Thermodynamics of Poly(acrylamide)/Sodium-Bentonite for Enhanced Phenol Removal from Aqueous Media

A composite based on polyacrylamide and Na-bentonite, designated as PAAm/Na-bentonite was prepared by in-situ radical polymerization using ammonium persulfate as an initiator and bis-acrylamide as a crosslinker. The structural and morphological features were examined by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunner − Emmet − Teller measurements. The results showed PAAm intercalation in the Na-bentonite layers. Equilibrium, thermodynamics, and kinetic studies were conducted by considering the effects of pH, initial phenol concentration, contact time and temperature. The zeta potential of the PAAm/Na-bentonite composite was calculated to understand the mechanism of phenol adsorption onto our product. The pollutant uptake behavior was determined by UV-Vis spectrophotometry. Adsorption results showed that PAAm/Na-bentonite composite showed a maximum adsorption of 160.3 mg.g−1 of 30 mg.L−1 phenol solution at pH 6 after 15 min of adsorption using 4 g.L−1 of the adsorbent. The presence of acrylamide modified the surface characteristics of the Na-bentonite and offered more adsorption sites as confirmed by XRD and SEM. Equilibrium modeling of the phenol removal process was carried out using Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich (D–R) adsorption isotherms. The equilibrium adsorption data were well fitted with the Langmuir model. In addition, the kinetics of adsorption were best described by a pseudo-second-order expression rather than a first-order model. The interactions between phenol molecules and adsorbent were explained by electrostatic as well as hydrogen bonding interactions, as confirmed by the pseudo-second-order kinetic model. A model for the interactions between the composite and the phenol molecules is proposed. The negative values of Gibb’s free energy (ΔG°) confirmed that the process was spontaneous. The positive value of change in entropy (ΔS° = 0.922 JK−1mol−1) suggests that the randomness was increased at the solution/solid interface. We suggest, the results indicate that PAAm/Na-bentonite presents a significant potential as an adsorbent material for phenol removal from aqueous solutions.

A PEWARNA ALAMI AKAR MENGKUDU (Morinda citrifolia L) SEBAGAI PENGGANTI SAFRANIN PADA PEWARNAAN GRAM NEGATIF

Noni is a plant that has the potential to be used as a therapeutic element, but many people are still unaware of its benefits. This plant is one of the herbal plants part of the noni plant has body parts that can almost all be utilised. Noni root or known as Morinda citrifolia L. can be processed and used as a natural dye because it contains morindon. Noni contains the molecule morindin, a disaccharide derivative of anthraquinone or anthraquinone, so its roots are used as a dye. Morindon is a natural dye produced when morindin glycoside is hydrolysed which will produce a red colour. Morinda citrifolia Linn fruit has antibacterial properties inherent in phenol and flavonoid molecules. The purpose of this study is to determine whether or not noni root extract can be used as an alternative to safranin gram staining. The variables used were noni root extract and gram staining which were carried out by Experimental Laboratories. This research began in May to June 2023. The results showed that noni root extract in a 60-second soak could colour gram-negative bacteria but in 20-second and 30-second soaks there was no red colour on gram-negative bacteria. Noni root extract can be applied as an alternative gram stain to safranin.

Molecular simulation of different VOCs adsorption on nitrogen-doped biochar

Nitrogen-doped biochar has potential application in the removal of volatile organic compounds (VOCs) from coal-fired flue gas. To explore the adsorption characteristics of different VOCs on nitrogen-doped biochar by molecular simulation, in this study, six typical aromatic VOCs (benzene, toluene, phenol, naphthalene, p-xylene, and chlorobenzene), and an amorphous carbon model with nitrogen/oxygen groups were selected and constructed. Grand Canonical Monte Carlo (GCMC) simulations were performed to evaluate the adsorption capacities of VOCs on nitrogen-doped biochar. The results showed that the optimized carbon model was in good agreement with the pore structure parameters of nitrogen-doped biochar, and the agreement of toluene adsorption capacities was more than 80 % at room temperature. The adsorption capacity of nitrogen-doped biochar for different VOCs was 184 − 317 mg/g with the order of phenol > naphthalene > p-xylene > toluene ≈ benzene ≈ chlorobenzene (single-component adsorption). Among them, the phenol molecule is more easily adsorbed due to its strong polarity, resulting in stronger electrostatic interaction with the adsorbent. The decrease rate of benzene adsorption capacity is the lowest with increasing adsorption temperature because of its low molecular weight. As gas concentration increases, van der Waals interactions between molecules and between molecules and porous carbon also increase, leading to an increase in VOCs adsorption capacity. Nitrogen-doped biochar not only has the highest VOCs/N2 selective adsorption coefficient for phenol (up to 36) but also has the highest adsorption capacity of 63 mg/g when 6 kinds of VOCs are multi-component adsorption at 25 °C. This study can provide references for the practical application of adsorption method in the removal of VOCs from coal-fired flue gas.