Papers by Keyword: Terephthalic Acid

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Authors: Wei Ling Zhang, Jian Fei Zhang, Zheng Li, Ji Xian Gong, Hui Ping Yang, Ke Ke Shang
Abstract: Biomodification of polyester film is a new field which can improve the surface property of material whithout environmental pollution and high energy consumption. Bacillus B-F which was isolated from waste water could biodegrade terephthalic acid. It was fermented and the broth was concentrated and used for surface process of polyester film. The modification lasted for 20 days. The surface property of the original and modified polyester film were tested. Contact angle examination showed that the hydrophilicity and surface free energy of the film was increased; XPS tests revealed the content of oxygen increased; FTIR showed that a small quantity of phenolic hydroxyl group appeared on the surface of the film; an oxygenase catalysed action might react at the surface of the film according to the degradation pathway of the simulacrum terephthalic acid.
Authors: Fa Xin Xiao, Yan Song Li, Xin Yang Xu, Xiao Ni Shen, Yong Peng Ren, Xiang Jun Zhang
Abstract: The 0.5 wt.% Pd/C catalysts used for purification of terephthalic acid(TA) were prepared, and the effects of dodecyltrimethylammonium bromide(DTAB) concentration on activity and microstructure of catalysts were investigated by means of SEM, TEM, XRD,HPLC,specific surface area(BET) and porosity test. The results show that DTAB can increase the activity of Pd/C catalysts, and the catalytic activity increases with the increase in DTAB concentration and nearly remains constant with further increase after it exceeds 0.5 wt.%.. DTAB can clean the surface of activated carbon and diminish the palladium size of Pd/C catalysts. The addition of DTAB has effects in crystal structure of nano Pd/C catalysts, and the Pd crystal planes of (111) and (200) was replaced by a broad reflections after DTAB added. DTAB tends to form various meta-stable structures(spherical or cylindrical)at the solid-liquid interface that helps finer grain for mation and hinders subsequent coarsening of the palladium particles.
Authors: Fa Xin Xiao, Yan Song Li, Xin Yang Xu, Yong Peng Ren, Xiao Ni Shen
Abstract: The traditional method of preparing 0.5 wt.% nano Pd/C catalysts used for pure terephthalic acid(PTA) refining is the precipitate-reduction method, and this paper proposed the sol-gel method, in which the palladium colloid was firstly prepared, and followed by the load process onto the activated carbon. The activity and microstructure of catalysts were investigated by means of SEM, TEM, EDS,XRD and HPLC. It was found that the activity of catalyst with the sol-gel method was much higher than that with precipitate-reduction method. The preparation technology has less effects on the micostructure of Pd/C catalysts, while the palladium particles of catalyst obtained with sol-gel method are much finer and the relatively palladium content is much higher.These two factors contribute to the higher activity of Pd/C catalyst.
Authors: Wen Sheng Linghu, Run Pu Shen
Abstract: Adsorption-catalytic oxidation of terephthalic acid (TA) from waster water using modified diatomite adsorbent was studied in this paper. Two diatomites were chosen for adsorbents and TA was used as a model compound. The process consists of physic adsorption of TA and catalytic oxidation of TA. The concentration of TA was determined by UV spectrometry. The results indicate that adsorption capacity of diatomite increased with the decrease of pH value of waster water. The equilibrium adsorbed amount of modified diatomite increased with the increase of metal content in the initial metal content range from 0 to 5% for both of Ni, Fe and Cu modified diatomite, and then the equilibrium adsorbed amount decreased after 5% metal content for Ni modified diatomite and in general kept constant for Fe and Cu modified diatomite. The maximum amount of TA adsorbed at the equilibrium stage was 4.40mg/g for Ni-5/RD. The adsorption capacity of raw and modified diatomite decreased obviously with the increase of cycle number in the initial first-fourth of cycle and then decreased very slowly in the 5th-10th of cycle. The Qe of Ni-5/RD, Fe-5/RD, Cu-5/RD and RD in the 10th cycle were 3.12, 2.44, 1.87 and 0.12mg/g, respectively. The result indicated that the modified could be repeatedly used and maintained the adsorption/regeneration performance stably through many batches of operation.
Authors: V. Lakshmi Narayanan, M.J. Umapathy
Abstract: 1,4-Bis (dimethyl) benzyl octyl ethylene diammonium bromide chloride has been synthesized, characterized and applied as new phase transfer catalyst in the alkaline hydrolysis of PET leading to depolymerisation. The new phase transfer catalyst has been compared with the alkaline hydrolysis of PET using zinc sulfate as catalyst in the depolymerization. It was found that the newly synthesized phase transfer catalyst exhibited excellent conversion than the alkaline hydrolysis of PET using zinc sulfate as catalyst.
Authors: Li Ping Wang, Gong Ying Wang, Fan Wang, Pin Hua Wang
Abstract: Metal-organic framework based on Zn2+ and terephthalic acid (TPA) was prepared and characterized by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. It was then used as the catalyst for the transesterification between diphenyl carbonate (DPC) and 1, 6-hexandiol (1,6-HD) to polycarbonate diol (PCDL). Compared to Mg-Al layered double hydroxide, triethylenediamine, sodium ethoxide and sodium methoxide, it exhibits the highest catalytic activity for the synthesis of PCDL. Under optimal reaction conditions(n(1,6-HD)/n(DPC) = 1.2, w(catalyst) = 0.03%, 198 °C), the yield of phenol is up to 90.1% in the transesterification process, and PCDL with higher Mn and lower hydroxyl value can be synthesized
Authors: Ning Ning Wu, Can Xiong Guo, Gui An Wu, Zhao Cai, Wan Hong He
Abstract: A novel one-dimensional metal-organic coordination polymer, [Zn (NH3)2(BDC)]n (BDC=1,4-benzenedicaboxylate), has been synthesized by solvent evaporation method through self-assembly of Zn (II) salts with terephthalic acid ligand in ammonia aqueous solution. Single crystal X-ray diffraction analysis indicated that each Zn (II) was coordinated by two nitrogen donors from two NH3 and two oxygen counter donors from terephthalic acid ligand. The adjacent zigzag chains are arranged in a parallel fashion and linked by interchain hydrogen bonding interaction and π-π stacking interactions into higher-dimensional framework. The compound has also been characterized by CHN elemental analyses, Single crystal X-ray diffraction analysis, powder X-ray diffraction (PXRD) analysis, Fourier transform infrared (FT-IR) spectra, Thermalgravimetric-differential scanning calorimetric (TG-DSC) and Solid-state nuclear magnetic resonance (NMR), etc. Results showed that the framework of compound was stable at the temperature up to 246°C. The desolvated product [Zn (BDC)]n, which was obtained by removal of molecular NH3 from [Zn (NH3)2(BDC)]n, can be transferred to the different skeleton structures through coordinating different small hydrogen-bond-forming molecules.
Authors: Urška Lavrenčič Štangar, Marko Kete, Urh Černigoj, Vilma Ducman
Abstract: Due to relatively successful application of TiO2 photocatalysis in the field of self-cleaning surfaces, a reliable and appropriate quantitative method for determining the self-cleaning efficiency of the products (photocatalyst films on different supports) should be widely recognized and established. Currently, the two standard methods are based on photobleaching of methylene blue aqueous solution in contact with thin solid catalyst layer, and on photodegradation of a solid fatty deposit (e.g. stearic acid) over catalyst layer followed indirectly by water contact angle (CA) measurements. Another method proposed recently is based on the entrapment of an organic dye in a solid polymer matrix deposited over the photocatalyst layer. Upon illumination, the dye (e.g. resazurin) is reduced by the photogenerated electrons to the form of a different colour or to the bleached form. Recently, a new method for determination of self-cleaning activity of photocatalytic surfaces was developed in our laboratory. It is based on the deposition of a transparent solid layer comprising terephthalic acid over the photocatalytic surface. When such a system is irradiated, among the other degradation products also a hydroxyterephthalic acid is formed due to a reaction between photoexcited TiO2 and terephthalic acid. Hydroxyterephthalic acid is a highly fluorescent molecule and can be easily detected by HPLC-FLD or spectrofluorimeter. Many different samples were tested using this method and using the standard method based on photodegradation of a solid fatty deposit over the catalyst layer. Regarding the sample (substrate) type, the focus was given to the self-cleaning ceramic tiles coated with TiO2-SiO2 thin films that were produced in cooperation with the major manufacturer of floor ceramic tiles in Slovenia, Martex d.o.o.. In case of self-cleaning ceramics and some other sample types, the advantages of the new method over standard methods were highlighted and critically evaluated.
Authors: Wei Ling Zhang, Jian Fei Zhang, Zheng Li, Ji Xian Gong
Abstract: Terephthalic acid is one of the main contaminations released by PET processing and it's toxic to environment and animals. Useful microbe must be found out to biodegrade it. Bacillus came from waste water may be powerful to biodegrade it, so the waste water were used as the sources of bacillus. The microbe was enriched in enrichment medium first and then isolated on selective medium containing terephthalic acid as the only carbon source to get the microbe suitable for degradation. The purified microbe was used to biodegrade terephthalic acid at different temperature to find out its suitable living and degradation condition. The microbe was identified with molecule biological identification and biolog express identification. The fermentation condition of the purified microbe was studied. The enzyme activity, growth condition and degradation condition was studied. The results showed that the isolated microbe was a kind of bacillus named comamonas testosteroni. It's powerful to degrade terephthalic acid at 37 °C with the rotational speed of 200 rpm. The pH of the medium would increase during degradation of substrate. The degradation would consumed a lot of oxygen. A degradation path may be deduced.
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