جستجوی مقالات مرتبط با کلیدواژه « phenol » در نشریات گروه « شیمی »

Viola odorata L. (Sweet violet) has been known with various biologic activities due to its secondary metabolites including flavonoids, glycosides, alkaloids, tannins and saponins. Nanoencapsulation of its extract can be an effective approach to improve the pharmaceutical application of Sweet violet phytochemicals. This study aimed to prepare encapsulated violet extract by two encapsulation methods and compare the antioxidant activity, and evaluate the encapsulation efficiency and physicochemical properties. The extract was encapsulated by double nanoemulsion (gum Arabic-gelatin complex) and nanoemulsion (Lepidium perfoliatum seed gum) methods and using the spray and freeze-drying processes. As a result, the highest encapsulation efficiency (85.82%) and more than antioxidant activity (136.67%) was in double nanoemulsion with freeze-drying. Nanoemulsions showed a higher stability index (97.75%) and greater emulsifying ability (99.84%) than double nanoemulsion due to higher zeta potential. . Due to Dynamic light scattering analysis, the nanoemulsion particle size (306.5 nm) was smaller than that of double nanoemulsion (798.3 nm). Density and moisture content of the double emulsion with freeze-drying were higher than those of nanoemulsions. The results implied elected methods effectiveness to prepare encapsulated Sweet violet extract, and obtained encapsulated extracts have the potential to be used in further pharmaceutical and food studies.

A composite, based on poly (acrylic acid‑co‑styrene) and organomodified montmorillonite with hexadecyltrimethyl ammonium bromide (27 wt. % in inorganics), designated as poly(AA-co-St)/HDTMA-MMT was prepared by in situ radical polymerization. The structural and morphological properties were examined by Fourier Transform InfraRed (FT-IR) spectroscopy, X-Ray Diffraction (XRD), and scanning electron microscopy (SEM). The results show the intercalation of poly (acrylic acid‑co‑styrene) in the organomodified montmorillonite layers. The percent of the inorganics in the composite is 27 % as evaluated by ThermoGravimetric Analysis (TGA). The performance of the composite to remove phenol molecules from an aqueous solution was investigated by batch adsorption, under different experimental conditions. The zeta potential of poly(AA-co-St)/HDTMA-MMT composite was calculated to understand the mechanism of phenol adsorption onto poly(AA-co-St)/HDTMA-MMT.The pollutant uptake behavior was determined by UV-Vis spectrophotometry. The best results were obtained for a contact time of 180 minutes, an initial concentration of 30 mg/L, pH 6. The presence of acrylic acid and styrene can modify the surface characteristics of the composite and affect the adsorption capacity as confirmed by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Interestingly, the maximum adsorption capacity was found to be 150.7 mg/g. Equilibrium modeling of the phenol removal process was carried out using the Langmuir and Freundlich adsorption isotherms. The equilibrium adsorption data were found to be well-fitted with the Freundlich adsorption isotherm. The kinetic of adsorption was 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 a composite and phenol molecule was proposed. Interestingly, the desorption of phenol from the adsorbent using hot water remains stable. The value of the first adsorption/desorption cycle was about 98.1 % and achieved 92.8 % after five cycles.

In this study, a series of LaCoO3 perovskite catalysts with varying calcination temperatures were synthesized hydrothermally, and their structure, morphology, and optical properties were investigated using X-Ray powder Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray electron spectroscopy analysis (XPS), Magnetic Property Measurement System (MPMS), and other characterization techniques. Using phenol as the target degradation product, the photocatalytic degradation reaction was carried out in the presence of visible light. In addition, the photocatalytic mechanism of LaCoO3 perovskite was also discussed. The experimental results showed that the LaCoO3 perovskite catalyst has been prepared with good crystallization. The particle size of the catalysts ranged from 10 to 40 nm, and the specific surface area decreased with calcination depth. Moreover, all the LaCoO3 catalysts showed strong paramagnetism, and the particles were regularly agglomerated under the action of magnetic force. LaCoO3 catalyst (the calcination temperature of 750 °C) exhibited high photocatalytic activity. In addition, the study of photocatalytic mechanisms revealed three degradation pathways for degrading phenol into inorganic small molecules such as CO2 and H2O via highly active HO•, HO2•, and h+ radicals.

There is interest in minimizing or eliminating the dependency on the use of non-recyclable, expensive and homogeneous catalysts. This can be achieved by replacing them with more durable nanoheterogeneous catalysts, which offer high catalytic performance and easy recoverability. Designing highly active and stable heterogeneous catalysts for the selective hydrogenation of phenol is still a challenge. In this study, a novel type of Pt/γ-Al2 O3 nanocatalyst is elaborately designed and prepared using a clean and green colloid-Microwave assisted synthetic method. The obtained nanocatalyst was characterized using TEM and BET analysis. The results of TEM and chemisorption characterization results confirm that the confined nanocatalyst possesses stronger Pt-Al2O3 interaction, with an excellent monodispersity of Pt nanoparticle on the surface of solid support. The prepared nanocatalyst exhibited enhanced catalytic activity and stability for the hydrogenation of phenol to cyclohexanone compared to the unsupported nanocatalyst. Cyclohexanone is widely used in pesticides, coatings, dyes, lubricants, and other industries due to its low volatility and high solubility. At 1 MPa, 3 hours, and 80 °C, a selectivity of 92.6 % and complete conversion of phenol to cyclohexanone were achieved.

In this study, removal of three toxic chemical pollutants, such as crystal violet (CV) dye, tetracycline (TC) drug, and phenol (PH) using sodium alginate-g-poly (acrylicacid-co-sodium, 4-ethenylbenzenesulfonate, hydrate)/Zinc oxide, and SA-g-poly(AC-co-EBS)/ZnO hydrogel composite was prepared by co-polymerization method by addition of free radicals. The hydrogel composite was characterized by TEM, FESEM, and XRD. Removal of laboratory sample aqueous pollutants (dyes, drugs, and phenol) using hydrogel composite to give low absorbance (0.0001) utilizing UV-Vis spectrophotometer for at a chosen wavelength for 2 h. Comparative between ((SA-g-(PAAc-co-EBS)/ZnO, (SA-g-(PAAc-co-EBS), and ZnO NPs) surfaces as adsorbents. The best results of the percentage of removal (E%) of three pollutants arrange in order increasing (SA-g-(PAAC-co-EBS)/ZnO NPs > SA-g-(PAAC-co-EBS) > ZnO NPs), the good results of the percentage removal (E%) of hydrogel composite, (92, 451%, 87.56%, and 82.56%) for CV, TC, and PH, respectively. Likewise, comparative between the amount of Zinc oxide nanoparticles (ZnO NPs) decorated of (SA-g-(PAAC-co-EBS) using (0.05, 0.08, 0.1, and 0.15 g). The good results of the percentage of removal (E%) of three pollutants about 0.1 g ZnO NPs. Re-cyclability and desorption studies indicated the best re-cycling performance of the prepared composite. Based on the results, the prepared hydrogel composites can be useful as a promising, ecological, cost-effective, and efficient material for dyes decontamination. Studies was carry out using several desorption agents at concentration (0.01 N) like HNO3, NaOH, H3PO4, H2SO4, HCl, and water. The hydrogel composite, was regeneration with 100% can be desorbed in diluted hydrochloric acid (0.01 N). The isotherm Freundlich and Langmuir models are also introduced, it has been found that all results follow the Freundlich model in the presence of three pollutants; this nonlinearity is higher when using the Freundlich model.

In this paper, phenol was determined in a liquid solution based on fabricating a phenol-selective electrode by cyclic voltammetry (CV). The carbon pa s te electrode was modified with nickel oxide nanoparticles (NiO) which were doped with nitrogen carbon quantum dots (NCQD) as the NiO-NCQD nanocomposite. The modified carbon pa s te electrode was manufactured in a laboratory and the effect of pH was s tudied. In the optimized condition, the be s t results were created at pH 7.0 and 4.0 using KH2PO4 buffer solution. By voltammetry, the voltage was optimized, and the be s t value for the voltages was obtained at 0.04166V and 0.05991V for pH 4 and 7, respectively. The scan rate (SR) was s tudied and the be s t SR was achieved at 100 mv s-1 for both pH. Due to the results, a wide linear dynamic range between 10 to 1000 μM was obtained. Also, the s tandard phenol solution was analyzed by high-performance liquid chromatography (HPLC). The retention time (RT), the wavelength maximum (λ max: nm), and the peak area equation of HPLC were achieved at 2.982 min, 270 nm, and (Area=40420CPhenol+ 43.557), respectively by the concentration range of 0.1-5.0 mg L-1. The modified carbon pa s te electrode with NiO-NCQD was used for determining phenol by cyclic voltammetry and compared with the HPLC technique. The results showed that there was no significant difference between the two methods.

Evaluation of plant responses under different environmental conditions is a principal step towards a better understanding of their function and performance. In this investigation, cumin (Cuminum cyminum), which is known as an important medicinal plant, was examined under three different growing conditions including natural habitat, field and greenhouse conditions in order to clarify the effects of growing conditions on essential oil properties. Essential oil (EO) content was higher in natural habitat samples, but the composition of EO was varied along the three samples extracted from the above three conditions. Overall, 17 compounds were detected and the key component in all samples was thymol, with the highest amount of 18.03% in natural habitat samples. Cuminaldehyde, γ-terpinene, α-thujene and limonene were other substantial compounds of the EO. Some elements were not detected in all samples such as p-cymene which was not extracted from the EO of natural habitat sample and acetoxylinalool which was not observed in greenhouse sample analysis. Regards to phenol content, natural habitat samples showed the highest amount and the lowest value was obtained on field sample. Radical scavenging activity of EO was also higher in natural habitat samples and with respect to phenolic content analysis, it could be considered as a substantial advantage rather than the others. To sum up, results indicated some advantages of natural habitat samples, although field samples also showed superiority in some parameters.

The behavior of phenol was s tudied and determined using the modified carbon pa s te electrode (MCPE) with nickel oxide nanoparticles doped by nitrogen carbon quantum dots as nanoadsorbent (NiO-NCQD) and cyclic voltammetry (CV). The MCP electrode was manufactured in a laboratory. The modified carbon pa s te consi s ted of 12% (NiONCQD), 44% of graphite powder and 44% of paraffin oil to get a modified carbonate pa s te. Cyclic voltammetry can provide behavior information; as such: diffusion coefficient (D), charge transfer coefficient (α.nα), the mass transport (mtrans) found that diffusion coefficient, the reducing of mass transport (mtrans) by increasing the phenol concentration in the solution, and increasing of con s tant K0 when the concentration of phenol increased in the solution. Also, the highe s t occupied molecular orbital (HOMO), lowe s t unoccupied molecular orbital (LUMO), and Gibbs free energy (ΔG) are s tudied and calculated. In this s tudy, EHOMO=4.92eV, ELUMO=0.32eV, and ΔG=-4.17 were considered. The drinking water samples from Latakia city were analyzed based on NiO-NCQD adsorbent using the MCPE method (NiO-NCQD/MCPE). The phenol concentration in the drinking water sample in Latakia was achieved less than the quantitative detection limit (LOQ), and the proposed procedure was validated by spiking samples.

Herein, we critically present theoretical modeling of toxic molecular compounds from biomass pyrolysis using the density functional theory formalism at the B3LYP level of theory coupled to 3-21G basis set. Detailed molecular modeling – geometry optimization, global hardness, and chemical potentials of the selected phenols and furans are reported. The thermal energy changes and reactivity are estimated from Gaussian’09 and Chemissian computational platforms. The formation of phenol and cresols are attributed to the thermally induced fragmentation of tyrosine via the rapture of the C-C bond (β-fission) which occurs via an endethermicity of +231.58 kJ/mol. The decarboxylation of tyrosine proceeds exothermally following an energy release of -14.36 kJ/mol. Subsequently, furans were formed from radical recombination during the thermal fragmentation of monomeric cellulose and tyrosine. The mechanistic formation of toxic molecular species from the thermal degradation of representative biomass materials has been proposed. From the global hardness data, it was noted that p-cresol was more reactive compared to phenol whereas alkylated benzofurans were more reactive than benzofuran because of their lower HOMO-LUMO energy gaps.

The exaggerated release of industrial wastes especially those containing phenol into the environment led to the contamination of both surface and groundwater supplies. In the present work a synergistic and combined system technique between three operations, adsorption of phenol via (rice husk or granular activated carbon GAC as adsorbents) together with stripping by airflow and advance oxidation via hydrogen peroxide as the oxidation agent, to evaluate the possibility of using a proposed new design for internal airlift loop reactor for removing the phenol from wastewater. The experiments were set up in a cylindrical Perspex column consisting of a transparent outer column having a 15 cm inside diameter and 150 cm height that included an internal draught tube of 7.5 cm and extending vertically to 120 cm top contains a bed having a dimension (7.5 x 30 cm) filled with adsorbent materials (rice husk, granular activated carbon GAC) and a volume capacity 25 liters. The experiments were conducted under the influence of both of the following variables air flow rate (2-20) (L/min), treatment time (5-60 min), the molar ratio of hydrogen peroxide to phenol,(1:10, 1:15, and 1:20)). The results showed the success of the proposed design with obtaining a removal efficiency (83%),( 81%)when using GAC and the rice husk as adsorbent materials respectively, with a minimum remediation time 60 minutes, airflow rate of 18 L/min, and molar ratio(20) hydrogen peroxide to phenol. This study demonstrated that the proposed synergistic system could be utilized for the remediation of contaminated aqueous systems.

This study was conducted to test the impact of flush number, mushroom size and cap openness on phenolic and flavonoid contents and antioxidant properties of button mushroom (Agaricus bisporus). Results showed that all tested facrors had a significant effect on dry matter and antioxidant properties of mushroom. The first flush had the highest dry matter in comparison with second and third flushs. Antioxiant activity and flavonoid content of mushrooms in second flush was significantly more than others but for phenol content, the first flush was the best. Surprisingly, the lowest antioxidant activity, phenol, and flavonoid contents were obseved in third flush. The highest antioxidant activity, phenol, and flavonoid content were recorded in large size, medium size, and small size of mushrooms, respectively. Cap of the mushroom showed significantly more antioxidant properties and flavanoid content, however, the phenol in stipe part was more than the cap part. Closed-cap mushrooms had significantly more dry matter and total phenol content, while no significant difference was seen in antioxidant activity and flavonoid compounds. In summary, mushrooms produced in third flush have lower dietary quality than first and second flushes, cap part of button mushroom was better than stipe and total antioxidant capacity was not affected by cap opening.

In the present research, Lacunary Keggin-type heteropolyoxometalate, (K7PMo2W9O39) supported on ZnO nanoparticles was prepared by the impregnation method. Nanoparticle characteristics and the remaining Keggin structure in the nanocomposites were confirmed by FT-IR and XRD analyses. The photocatalytic activity of prepared K7PMo2W9O39/ZnO for degradation of phenol under UV light was investigated.  H2O2 was used as an oxidant in the photocatalytic degradation process of phenol. The results indicated that synthesized nano photocatalyst could be considered an appropriate heterogonous photocatalyst in the removal of organic pollutants from aqueous solutions and heterogenization of Lacunary Keggin-type heteropolyoxometalate on ZnO nanoparticles resulted in the improved light absorption intensity and decreased band gap of nanocomposites. Degradation of phenol in the presence of the K7PMo2W9O39/ZnO could lead to the disappearance of approximately 93% of phenol after 60 min. But degradation for the same experiment performed in the presence of the K7PMo2W9O39 or /ZnO was less than 60% at the same time.

The wet peroxide oxidation (CWPO) of phenol in the polluted water on Mg-Al nano mixed oxide was investigated and the optimization and kinetic of the process were studied. The nanocatalyst was characterized by XRD, FESEM, EDS and BET. The average crystallite size of 25 nm was estimated using Scherrer formula.FESEM images approved the catalyst comprised of spherical nanoparticles in the range of 94-130 nm. BET results indicated the mesoporous nanocatalyst (dpore=21 nm) has a specific surface area of 86.3 m2.g-1. The optimized conditions of the process resulted at initial concentration of phenol, reaction temperature, reaction time and hydrogen peroxide volume of 100 ppm, 60ºC, 55 min and 3 mL, respectively. The phenol degradation under the optimal conditions reached 85%. The result of the kinetic study indicated that the oxidation of phenol over Mg-Al nano mixed oxide follows the pseudo-first-order kinetics with a correlation factor of 0.94. The activation energy of phenol oxidation over the catalyst was determined to be 19.07 kJ.mol-1. The Mg-Al mixed oxide is a cheap and green catalyst and could be prove to promising for the CWPO process.

The applicability of Mn-doped Fe2O4 nanoparticles loaded on activated carbon for removing Phenol from aqueous solutions has been reported. This novel material was characterized by different techniques such as FT-IR, XRD and SEM. The influence of nanoparticle dosage, pH of the sample solution, individual Phenol concentration, contact time between the sample and the adsorbent, temperature, and ionic strength of the sample solution were studied by performing a batch adsorption technique. The maximum removal of 5-25 mg L-1 of individual Phenol from an aqueous sample solution at pH 6.0 for Phenol was achieved within 30 min when an adsorbent amount of 0.1 g was used. It was shown that the adsorption of Phenol follows the Langmuir isotherm model best described the experimental adsorption data with maximum adsorption capacities of 4.27 mg/g. The kinetic data were best described by the pseudo-second order model (R2 = 0.9997) explains equilibrium data. Isotherms had also been used to obtain the thermodynamic parameters such as free energy (ΔG0), enthalpy (ΔH0) and entropy (ΔS0) of adsorption. The negative value of (ΔGo, ΔHo and ΔSo) confirmed the sorption process was endothermic reflects the affinity of Mn-doped Fe2O4 nanoparticles loaded on activated carbon functionalized towards Phenol. These results indicate that the pretreatment of Mn-doped Fe2O4 nanoparticles loaded on activated carbon can optimize the removal of Phenol from aqueous solution.

Since phenol is toxic and yet its biologic reduction and removal is so difficult, strict limits are applied for the discharge of phenol-containing substances in the environment. Discharge of phenol-containing industries, sewages into natural waters is a serious threat to human health. In this study, the main objective is to consider the possibility of removing phenol with high initial concentration using a Heterogeneous Photocatalytic process. First, the absorbent SBA-15 and Graphene oxide(GO), which are the most efficient absorbents among others for phenol removal, and then, nanocomposites Titanium dioxide(TiO2)/SBA-15 and TiO2/GO were synthesized. Then, the structural and physical properties of nanocomposites were identified through X-Ray Diffraction (XRD), Brunauer–Emmett–Teller (BET), Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM) analysis. Considering the results of the Response Surface Method (RSM) for phenol removal in the initial study, nanocomposites TiO2 / SBA-15 and TiO2 / GO were used to remove the same amount of phenol from aqueous solutions.

In the present study, hollow fiber liquid-phase microextraction (HF-LPME) method was used to preconcentrate trace amount of phenol prior to its spectrophotometric determination. Phenol reacted with 4-aminoantipyrine (4-AAP) reagent in presence of potassium hexacyanoferrate (III) and then was extracted into the octanol extractant inserted into the lumen and pores of hollow fibers. Some factors such as concentrations of 4-aminoantipyrine, potassium hexacyanoferrate (III) and ammonium chloride, the rate of stirring, and extraction time were optimized using response surface method based on the central composite design (CCD). Under the optimum conditions, the limit of detection (LOD) and limit of quantification (LOQ) were obtained as 1.5 and 5 μg L-1, respectively. Also, the relative standard deviation (RSD %) and enrichment factor (EF) were obtained as 4.9 % and 174, respectively. In addition, the suggested method was implemented to measure of phenol concentration in some real samples, including wastewater of wood and textile factories, as well as the extracts of mint, and green tea. The accuracy was investigated by the recovery of phenol from real samples in the range of 82.3 – 112%. The results showed that the proposed method is simple, rapid, eco-friendly, and accurate for preconcentration and analysis of phenol.

A novel bio electrode containing bacteria immobilized on clay mixed carbon paste electrode (Bactria-clay-CPE) is developed for detection and degradation of the phenolic solutions based on electrochemical techniques such cyclic voltammetry, square wave voltammetry, electroctrochemical impedence spectroscopy. The results obtained showed that bacteria-clay-CPE exhibited excellent electro-catalytic activity towards phenol. The recorded cyclic voltammogram shows that the oxidation of phenol is manifested by the appearance of four oxidation peaks

Here, the electrochemical carbon sensor modified with titanium oxide (TiO2) nanoparticles and 5-Chloro, 2, 4-dihydroxyphenyl imidazo [4,5-d] [1,3] thiazin 7(3H)-one, an imidazole derivative, (CHIT) was fabricated for hydroxylamine (HX) determination. After optimization, some kinetic parameters related to CHIT were obtained. The observations revealed that using CHIT with TiO2 nanoparticle affected in lowering value of oxidation potential and increasing of oxidation peak currents, which provides higher sensitivity. According to these results CHIT-TiO2-CPE sensor possess the linear range (0.5–850 μM) (0.5-40 and 40-850 μM) and a low detection limit (DL) 0.08 μM according to 3sb/m. Also CHIT-TiO2-CPE was used for determination of phenol in the range of 90 μM to 800 μM in the presence of various concentration of HX. Also, the CHIT-TiO2-CPE was used in water samples, successfully.

This study demonstrates removal of phenol from aqueous solution using the carbons prepared from the natural sources, i.e. olive-pit, date-pit, and pomegranate-kernel in a batch system. For comparison purpose, the adsorption tests were also carried out on a commercial activated carbon. Influences of effective parameters such as pH, adsorbent dosage, contact time, phenol initial concentration and temperature on the removal of phenol from water were investigated. The optimum conditions for maximum adsorption were determined. In this work, the Langmuir and Freundlich models were chosen to evaluate the adsorption isotherms of phenol. The experimental isotherms showed that Freundlich isotherm fit adequately the experimental data for all adsorbents used. The adsorption data followed closely the pseudo-second-order. In addition, thermodynamic analysis was carried out for phenol adsorption. In this work, the two conventional analysis techniques, Fourier transform infrared (FTIR), and scanning electron microscopy (SEM), were used to investigate the structural and morphological properties of the adsorbents surface.