Papers by Keyword: Phenol

Abstract: The aim of this work is to investigate phenol removal by immobilized peroxidase extracted from cauliflower stem. Peroxidase was partially purified by membrane filtration and diafiltration. Almost four-fold increase in the measured activity of partially purified peroxidase was obtained. The enzyme was then immobilized on to the surface of regenerated cellulose ultrafiltration membrane (molecular weight cut-off 30 kDa) using a dead-end filtration unit. Three different immobilization methods (physical adsorption, cross-linking and covalent-bonding using glutaraldehyde as a membrane activator) were tested. The immobilization and enzymatic reaction efficiency were evaluated in terms of the immobilization yield, the enzyme leakage from the system, the phenol removal and the permeate flux. Results showed that the immobilization methods did not much affect the permeate flux of the membrane. The peroxidase immobilization by covalent-bonding on regenerated cellulose membrane produced the highest immobilization yield and the lowest enzyme leakage. The immobilized enzymatic reaction efficiency on phenol removal was 100% at operational time 60 min and reduced to 96.4% at 600 min.

Abstract: Fe-SBA-15 materials with different Fe content have been prepared using tetraethyl orthosilicate (TEOS) and iron nitrate (Fe (NO₃)_3·H₂O as precursors and Pluronic P123 as structure directing agent through evaporation-induced self-assembly (EISA) method. The materials were characterized by nitrogen sorption, powder X-ray diffraction and TEM. All the Fe-SBA-15 samples appeared ordered 2D hexagonal mesostructure. The BET surface area and pore diameter were about 500 m²/g and 4 nm respectively. In the reaction of phenol hydroxylation to dihydroxybenzenes, the Fe-SBA-15 materials showed good catalytic activity, giving 20.2% of phenol conversion, 58.2% of selectivity for o-dihydroxy benzene and 41.8% of selectivity for p-dihydroxy benzene. After five cycles, the product yield was 25.2%, while selectivities of o-dihydroxy benzene and p-dihydroxy benzene were 58.2% and 41.8%, respectively. All these findings indicated the potential of Fe-SBA-15-10 could be used as a cost-effective, environment-friendly catalyst.

Abstract: β-Cyclodextrin polymer were prepared by inverse-phase suspension polymerization using epichlorohydrin (EPI) as crosslinker. The architecture has been characterized by Fourier transform infrared spectra (FT-IR) and thermogravimetric analysis (TGA), which confirmed that cyclodextrin polymer have been synthesized successfully. β-Cyclodextrin polymer (EPI-CD) can interact with a variety of hydrophobic compounds to form inclusion complexes, such as phenol. Experimental results indicated that the adsorption reached to 58.51umol/g under the initial concentration of 120mg/L at 298K. The adsorption isotherm was fitted to the Langmuir and Freundlich models. From the experimental data, it may be inferred that EPI-CD polymer was an effective adsorbent for the removal of phenol in wastewater treatment.

Abstract: This article presents the results of experimental obtaining together with tests of modifications of the granulated sorption aluminosilicate-based material. The chemical composition, structure and morphology of a surface of the obtained modifications of sorbents from clay have been explored. Through a complex of modern physical methods it is established that porosity and a specific surface of clay-based sorbents increased as a result of modification. Pilot studies have shown higher efficiency of new aluminosilicate-based sorbents in comparison with absorbent carbon during sorption of such model pollutants as methylene blue, phenol and ions of heavy metals. Modifications of sorbent which can be effectively used for post treatment of wastewater are revealed.

Abstract: The photocatalytic oxidation of phenol on the composite copper oxide (II) modified titania photocatalyst (CuO/TiO₂) with sunlight irradiation at high oxygen pressure are studied. The photocatalyst characterized by Scanning electron microscopy (SEM), UV-Visible Diffuse Reflectance spectroscopy (UV-DRS), Surface area analysis, and X-ray diffractometry (XRD). The composite photocatalyst based on the anatase includes 3% copper oxide (II). The CuO/TiO₂ photocatalytic activity was investigated of phenol oxidation with sunlight irradiation at high oxygen pressure. The photocatalytic oxidation of phenol described Langmuir-Hinshelwood equation and calculated its parameters. With the increasing, the oxygen pressure the rate of phenol photocatalytic oxidation also increases. The quantum yield of the photocatalytic phenol oxidation at high oxygen pressure on the CuO/TiO₂ composite photocatalyst are obtained.

Abstract: Phenol and phenolic compounds in wastewater from various industries were toxic to water livings and human even in ppm concentration. A number of photocatalysts and adsorbents were applied for the low cost and good efficiency wastewater management to reduce phenol concentration in water. In this work titanium dioxide, one of high efficiency photocatalysts which is widely used in water treatement, was coated on the fabricated adsorbent composite substrate. The composite substrate composed of activated carbon and NaA zeolite presents high phenol adsorption because of high porosity and good ion exchange properties resulting in good adsorption property. Accordingly, the absorption could promote the photocatalytic activity of TiO₂ catalyst. As the specimens were easily disposed after water treatment process, therefore, it was a good choice for lower energy consumption. The composite substrate was easily fabricated by simple extrusion and fired under non oxidation atmosphere at 650°C for 3 hours. Then polyurethane foam was inserted into the composite substrate to make it be able to float and be swirled by wind near water surface to get more UV excitation than deeper water. Phenol concentration was investigated by the UV absorbance at 270 nm using UV-Vis spectrophotometer. The XRD and SEM were used to study phase crystal structure and morphology of the composite.

Abstract: Classification of simple supramolecular structures (for example molecular complexes), which has been introduced and described by Mulliken [1], is based on types of molecular orbitals of the components. In the paper [2], disadvantages of such classification are shown, which motivate us to return to the re-examination properties of molecular complexes. By this reason, there is a need to research the molecular complexes of one electron acceptor with a wide range of electron donor molecules. This paper have continued work (Part I [3]) on the chloranil complexes by studying the spectral properties complexes of N- and O-unsubstituting anilines and phenols. The present work aimed at analyzing linear relation the energies of charge-transfer bands of molecular complexes are related to ionization potentials of the donor components. All complexes conform to linear relations like involving both adiabatic and vertical ionization potentials of donor components. Mulliken [1] has been proposed to apply the vertical ionization potentials of donor components only. The development of photoelectron spectroscopy has led to the measurement of adiabatic and vertical ionization energies for thousands of molecules, which allow theirs to the present analysis of spectral properties molecular complexes.

Abstract: Impure BiFeO₃ as a visible light photocatalyst for phenol degradation was synthezied via solid state method. The calcined temperatures of catalysts were studied. The characteristics of the catalysts were determined by XRD, SEM/EDS and BET. The catalysts were mainly composed of rhombohedral distorted perovskite-type BiFeO₃ phase with impurity phases (B₂Fe₄O₉, Bi₂₅FeO₄₀ and Bi₂O₃). Photocatalytic activity of phenol (5 mg/l) was studied in the impure BiFeO₃ illuminated with 200 w fluorescence lamps. The catalyst amount and initial pH value of phenol solution on the photocatalytic effiency have been also investigated. In the present experiments, the catalyst calcined at 800°C shows the highest activity. The optimum loading of impure BiFeO₃ and pH value were obtained to be 0.5 g/l and 6, respectively.

Abstract: Photocatalysis has been proven effective in controlling various environmental problems originated by pollutions both in liquid and gaseous phases. Titanium dioxide (TiO₂) is well known the most practical photocatalyst as it has high photocatalytic efficiency, low band gap energy, and no toxicity. Various chemical methods have been tried to produce TiO₂ photocatalyst powder with high activity. In this study, sol-gel method has been employed to produce nanosized TiO₂ photocatalyst particles and its physical properties and photocatalytic activity in phenol degradation test were compared with the commercial TiO₂ powder, Degussa P25. The synthesis process was carried out through hydrolysis of titanium tetraisopropoxide (TPT) and methanol where the molar ratio of water to TPT was monitored to control the hydrolysis rate. From X-Ray Diffraction (XRD) analysis, the sol-gel TiO₂ powder obtained was fully in anatase structure with high crystallinity. Scanning Electron Microscope (SEM) measurement showed that the powder was in nanoto sub-micron size, spherical in shape, and tightly agglomerated. Thermal analysis confirmed that sol-gel derived amorphous TiO₂ powder transformed to anatase phase after 400°C calcination. The test on photocatalytic performance conducted using aqueous solution of phenol as the representative of water pollutant examined in this study showed that the sol-gel TiO₂ powder is more efficient in degrading phenol compared to one of the most active photocatalysts commercially available, Degussa P25.

Abstract: Fe₂O₃/γ-Al₂O₃ catalysts were prepared by the method of wet impregnation and were characterized by X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), N₂ adsorption and Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES), respectively. The activity of Fe₂O₃/γ-Al₂O₃ for catalytic wet peroxide oxidation (CWPO) of phenol was tested. The effects of the initial pH of the phenolic aqueous solutions and the iron content of Fe₂O₃/γ-Al₂O₃ on phenol degradation have been studied. The results indicated that almost total removal of phenol and considerably high reduction of COD for the initial phenol concentration of 100-1000 mg/L were achieved under mild conditions. The leached iron from the catalyst was negligible.