Terephtalic Acid Research Articles

First principles investigation of manganese catalyst structure and coordination in the p-xylene oxidation process

The oxidation of p-xylene to terephtalic acid is important for the production of polyethylene terephthalate (PET). This work investigates the coordination of the Mn catalyst species under operating conditions.

Preparation of a new green magnetic Fe3O4 @TiO2-P25 photocatalyst for solar advanced oxidation processes in water

A novel green method has been investigated to obtain a magnetic recoverable photocatalyst. Fe3O4 particles formed in situ by aerial oxidative precipitation of aqueous Fe(II) in the presence of terephthalate were bonded to TiO2-P25 nanoparticles, giving rise to a coupled semiconductor heterostructure with superparamagnetic behavior at room temperature (Fe3O4 @TiO2-P25). The synthesis method is carried out in water at room temperature with almost full recovery and recycling of terephtalic acid. The prepared samples were fully characterized by XRD, TGA-DTA-MS, ATR-FTIR, WDXRF, TEM, SEM/EDX, N2 adsorption-desorption, elemental analysis, XPS, DRS, PL spectroscopy and SQUID. Photo-stability tests showed that Fe3O4 @TiO2-P25 does not undergo photodissolution under simulated solar radiation. The photocatalytic performance of Fe3O4 @TiO2-P25 was examined based on its ability to degrade aqueous metoprolol under UV–vis radiation in the presence of O2 and O3/O2. Also, the catalyst was successfully reused in six solar photocatalytic ozonation runs with negligible loss of photocatalytic activity.

Determinants for an Efficient Enzymatic Catalysis in Poly(Ethylene Terephthalate) Degradation

The enzymatic degradation of the recalcitrant poly(ethylene terephthalate) (PET) has been an important biotechnological goal. The present review focuses on the state of the art in enzymatic degradation of PET, and the challenges ahead. This review covers (i) enzymes acting on PET, (ii) protein improvements through selection or engineering, (iii) strategies to improve biocatalyst–polymer interaction and monomer yields. Finally, this review discusses critical points on PET degradation, and their related experimental aspects, that include the control of physicochemical parameters. The search for, and engineering of, PET hydrolases, have been widely studied to achieve this, and several examples are discussed here. Many enzymes, from various microbial sources, have been studied and engineered, but recently true PET hydrolases (PETases), active at moderate temperatures, were reported. For a circular economy process, terephtalic acid (TPA) production is critical. Some thermophilic cutinases and engineered PETases have been reported to release terephthalic acid in significant amounts. Some bottlenecks in enzyme performance are discussed, including enzyme activity, thermal stability, substrate accessibility, PET microstructures, high crystallinity, molecular mass, mass transfer, and efficient conversion into reusable fragments.

Modification of bimetal Zn/ Mg MOF with nanoparticles Fe3O4 and Fe3O4@SiO2, investigation of the peroxidase-like activity of these compounds by calorimetry and fluorimetry methods

In this article; the bimetal metal-organic framework Zn/Mg (Zn/Mg MOF) is synthesized.Then Zn/Mg MOF bimetal was combined with Fe3O4 and Fe3O4@SiO2, and composites of Fe3O4@ SiO2/MOF/Dextrin, Fe3O4@SiO2/MOF, Fe3O4@MOF/Dextrin and Fe3O4@MOF made. The peroxidase-like activity of these compounds was investigated and compared by calorimetric Resazurin (Rz) and O-phenylenediamine (OPD); (Rz-H2O2, OPD-H2O2) and fluorimetric Rz and terephtalic acid (TA); (Rz-H2O2, TA-H2O2). The Fe3O4@ MOF/Dextrin composite has the highest peroxidase-like activity. The effect factors (amount of pH (6), the values of TA (1.37 mM), H2O2 (0.025 mM), reaction time (8.15 min), and amount of Composite (116.67 mg)) to increase the catalytic activity of Fe3O4@ MOF/Dextrin measured by chemometrics method. The most suitable linear range of the calibration curve by the TA-H2O2 -Composite fluorimetric method is 1–600 μg L−1, and the detection limit is 2.27 μg L−1. The relative standard deviation (RSD%) for measuring concentration atropine 1 μg L−1 (n = 6) is 1.18%. Finally, from this system for measuring atropine extracted by the Liquid-liquid extraction (LLE) method in two types of plants, D. Innoxia north and west and D. stramonium north and west of Iran (118.25 μg L−1, 79.80 μg L−1) and (18.477 μg L−1, 9.27 μg L−1) used, respectively.

Seawater activated TiO2 photocatalyst for degradation of organic compounds

The world's oceans are polluted by a continuous inflow of plastic. Plastic fragments finally into microplastic, which can be taken up, for example by plankton, and subsequently by the entire ocean food web. An approach to reduce plastic pollution constitutes the accelerated microplastic degradation in marine environments. TiO2 (anatase) is commonly used as an oxidative photocatalyst and well known to catalyze the degradation of organic compounds upon UV irradiation.In this study, a selective activation of TiO2 (anatase) particles encapsulated by Ca- or Sr-polyphosphate is presented. The TiO2 polyphosphate core-shell particles are envisaged as additives in plastic products. The highly concentrated cations from seawater, viz. Na+ and Mg2+, displace the Ca2+ or Sr2+ cations from the polyphosphate shell. As a result, the polyphosphate coating dissolves and thus the photocatalytically active TiO2 core is released. The stability of the TiO2 polyphosphate particles in potable water and the seawater activated disintegration of methylene blue, methyl methacrylate, terephtalic acid, and poly(vinyl alcohol) was shown. It has been demonstrated, that the sweetwater stable polyphosphate coating degrades in the presence of seawater, which could be monitored by the activation of the TiO2 (anatase) photocatalyst.

A Novel Class of Cost Effective and High Performance Composites Based on Terephthalate Salts Reinforced Polyether Ether Ketone.

Poly(ether ether ketone) (PEEK)-based nanocomposites have been realized with incorporation (0–30 wt %) of anhydrous calcium terephthalate salts (CATAS), synthetized by reaction of terephtalic acid with the metal (Ca) oxide, by means of a melt processing. Their structure, morphology, thermal, and mechanical properties have been investigated. Scanning electron microscopy observations confirmed homogeneous dispersion of nanometer-sized fillers and a toughened fracture morphology even at the higher content, while thermal characterization confirmed an unvaried thermal stability and unmodified crystalline structure of the reference PEEK matrix. A negligible nucleating effect was evidenced, while a blocking effect of the amorphous phase fraction provide composites with increased stiffness, confirmed by enhanced values of G’ and shifts of glass transition peak to higher temperatures, for restriction in chain mobility imposed by CATAS. The proposed solutions aimed to enlarge the application range of high performance costly PEEK-based composites, by using thermally stable nanofillers with limited costs and easily controllable synthesis phase.

Hydroxyl radicals and oxidative stress: the dark side of Fe corrosion

Fe-based materials are considered for the manufacture of temporary implants that degrade through the corrosion of Fe by oxygen. Here we document the generation of hydroxyl radicals (HO) during this corrosion process, and their deleterious impacts on human endothelial (ECs) and smooth muscle cells (SMCs) in vitro. The generation of HO was documented by two independent acellular assays, terephtalic acid hydroxylation (fluorescence) and spin trapping technique coupled with electron paramagnetic resonance spectroscopy. All Fe-based materials tested exhibited a strong potential to generate HO. The addition of catalase prevented the formation of HO. Cellular responses were assessed in two ECs and SMCs lines using different cytotoxicity assays (WST-1 and CellTiter-Glo). Cells were exposed directly to Fe powder in the presence/absence of catalase, or to extracts obtained from the corrosion of Fe. Cell viability was dose-dependently affected by the direct contact with Fe materials, but not in the presence of catalase or after indirect exposure to cell extracts. The deleterious effect of HO on ECs and SMCs was confirmed by the dose-dependent increase of the transcripts of the oxidative stress gene heme oxygenase-1 4 h or 6 h after direct exposure to the particles, but not in presence of catalase or after indirect exposure. The demonstration of HO production during corrosion and consequent oxidative stress on human ECs and SMCs newly reveals a deleterious consequence of Fe-corrosion that should be integrated in the assessment of the biocompatibility of Fe-based alloys.

GENERATION OF RADICALS IN FERROUS-PERSULFATE SYSTEM USING KRCL EXCILAMP

Generation of sulfate radical anion (SО4•–) and hydroxyl radical (•OH) in the ferrous-persulfate system (UV/PS/Fe2+), activated with KrCl excilamp (222 nm) radiation, was studied. To detect radicals and evaluate levels of their action, degradation experiments were conducted using the probe compounds, which trap the target radicals – terephtalic acid (TPA) and p-chlorobenzoic acid (pCBA). Deionized water (DW), natural water (NW) and wastewater (WW), containing a probe compound, were sequentially treated by direct UV, UV/PS and UV/PS/Fe2+ systems. The ferrous-persulfate system was shown to be the most efficient in terms of radical generation within the same water matrix: UV/PS/Fe2+ > UV/PS > UV. Comparing different water matrices, the lowest radical generation was observed in WW. Since TPA and pCBA were unsuitable compounds to assess the contributions of SО4•– and •OH by comparison of degradation degree with and without methanol and tert-buthanol, herbicide atrazine (ATZ) was taken as a model organic pollutant with comparable reaction rate constants with SО4•– and •OH. Scavenging experiments with ATZ and alcohols showed a major contribution of SO4•– during UV/PS/Fe2+ treatment of DW (79%) and NW (60%), whereas SO4•– and •OH contributed equally in WW. Direct UV irradiation (without persulfate and Fe2+) indicated the •OH production in WW, presumably, due to high photoreactivity of dissolved organic substance (DOM).

Reactive oxygen species produced by the corrosion of Fe-based materials induce endothelial dysfunction

Based on their good mechanical properties, bioresorbable Fe-based materials have been proposed during the last decade as candidate alloys for coronary stents. Previous investigations on the biocompatibility of metallic materials often overlooked the complexity of the biodegradation phenomenon. We document, for the first time, the generation of reactive oxygen species (ROS) during Fe-based materials corrosion and their deleterious impacts on endothelial function. ROS generation was evaluated by the terephtalic acid (TA) hydroxylation assay. The endothelium of rat aortic rings was directly exposed (6 h) by inserting an iron wire into the lumen in the presence/absence of catalase. Indirect exposure to iron wire was included to assess the potential role of solubilized iron ions. Nitric oxide (NO) production by rings was measured by EPR spin-trapping, and endothelium-dependent relaxation was assessed with the organ-bath method. Induction of oxidative stress in rings was assessed via the mRNA expression of the oxidative stress response gene heme oxygenase-1 (HO-1). Iron exhibited a strong potential to generate ROS in the TA assay. ROS generation, but not corrosion, was inhibited by catalase. Direct contact with iron significantly impaired endothelium-dependent relaxation of aortic rings. Direct contact with the material in the presence of catalase, or indirect contact did not affect endothelium function. NO production by isolated rat aortic rings was inhibited by ROS generated by the corrosion of iron, as indicated by the protective role of catalase. Expression of HO-1 was increased after direct exposure to iron, not to indirect exposure or in the presence of catalase. The demonstration of ROS production during corrosion, induction of oxidative stress, inhibition of NO production and consequent endothelium dysfunction raise concern about the biocompatibility of biodegradable Fe-based alloys for vascular implants.

Long-Persistent Circularly Polarized Phosphorescence from Chiral Organic Ionic Crystals.

Long-persistent circularly polarized phosphorescence (LPCPP) is achieved for the first time in chiral organic ionic crystals at room temperature. The co-crystal composed of terephtalic acid (TPA) and chiral α-phenylethyamines (PEAs) gave rise to LPCPP with lifetimes up to 862 ms and large dissymmetric factor (glum ). The hybridization of TPA with chiral PEAs allows circular polarization of the generated long-persistent phosphorescence. The observed mirror-image twisted molecular structures in the rigid lattices were responsible for the chiroptical activation of the generated long-persistent phosphorescence.

Assembly of Robust Holmium-Directed 2D Metal-Organic Coordination Complexes and Networks on the Ag(100) Surface.

We describe the formation of lanthanide-organic coordination networks and complexes under ultra-high-vacuum conditions on a clean Ag(100) surface. The structures comprise single Ho atoms as coordination centers and 1,4-benzenedicarboxylate (from terephtalic acid, TPA) as molecular linkers. Using low-temperature scanning tunneling microscopy, we find two different chiral phases of surface-supported metal-organic structures incorporating Ho atoms. Density functional theory calculations can explain the structure of both binding motifs and give possible reasons for their varying formation under the respective Ho/TPA ratios, as well as deposition and annealing temperatures. Metal-ligand interactions drive the formation of cloverleaf-shaped mononuclear Ho-TPA4 complexes establishing supramolecular arrays stabilized through hydrogen bonding. A 2D lanthanide-organic reticulation is observed when changing the stoichiometry between the two building blocks. The combined insights from scanning tunneling microscopy and density functional theory reveal the relative stability, charge transfer, and bonding environment of both motifs.

Depolymerization and Assimilation of Poly (Ethylene Terephthalate) By Whole-Cell Bioprocess

Now, biofunctionalization of synthetic polymers can be achieved through biocatalysts. Uniquely among the great enzyme, whole-cell biocatalysts provide a promising alternative for bioprocess. The bioprocess of depolymerization and assimilation of polyethylene terephthalate (PET) was investigated with whole-cell from aeromonas as biocatalyst in this investigation. The engineered aeromonas strain, which can grow with PET particle as sole carbon source and major energy, was employed as biocatalysts. The main products, such as terephtalic acid (TA), bis (2-hydroxyethyl terephthalate) (BHET) and benzoic acid (BA), muconic acid (MA), were recognized in whole-cell bioprocess of PET depolymerization. It showed that variation of these products was more complex than that in case of enzyme treatment, for the interaction of solid insoluble substrate, microbe cell and enzymes secreted by cells in this heterogeneous process. The result demonstrated that not only the ester bonds can be cleaved, but also the benzene ring can be decomposed in the process of whole-cell catalysis. And some of the intermediate products, which have inhibiting effect in enzyme catalysis process, can be utilized and further degraded in whole-cell bioprocess. Furthermore, assays by DSC showed that as degradation of PET progressed, crystallinity of PET granular increased by 1.81% due to preferential degradation of amorphous regions.

Phosphinic Acid Based Linkers: Building Blocks in Metal-Organic Framework Chemistry.

Metal-organic frameworks (MOFs) are a chemically and topologically diverse family of materials composed of inorganic nodes and organic linkers bound together by coordination bonds. Presented here are two significant innovations in this field. The first is the use of a new coordination group, phenylene-1,4-bis(methylphosphinic acid) (PBPA), a phosphinic acid analogue of the commonly used terephtalic acid. Use of this new linker group leads to the formation of a hydrothermally stable and permanently porous MOF structure. The second innovation is the application of electron-diffraction tomography, coupled with dynamic refinement of the EDT data, to the elucidation of the structure of the new material, including the localization of hydrogen atoms.

Phosphinic Acid Based Linkers: Building Blocks in Metal–Organic Framework Chemistry

AbstractMetal–organic frameworks (MOFs) are a chemically and topologically diverse family of materials composed of inorganic nodes and organic linkers bound together by coordination bonds. Presented here are two significant innovations in this field. The first is the use of a new coordination group, phenylene‐1,4‐bis(methylphosphinic acid) (PBPA), a phosphinic acid analogue of the commonly used terephtalic acid. Use of this new linker group leads to the formation of a hydrothermally stable and permanently porous MOF structure. The second innovation is the application of electron‐diffraction tomography, coupled with dynamic refinement of the EDT data, to the elucidation of the structure of the new material, including the localization of hydrogen atoms.

Synthesis and Characterization of Terephthalic Acid Based Cr3+, Sb3+, In3+ and V3+ Metal-Organic Frameworks

The metal organic frameworks (MOFs) were synthesized by the reaction of the benzene-1,4-dicarboxylic acid (terephtalic acid (TPA)) ligand with the corresponding metal salts such as CrCl3, SbCl3, In2(SO4)3, and VCl3 in 1:2 molar ratio. These complexes were characterized by the BET measurement, scanning electron microscopy, thermogravimetric analyzer (TGA), magnetic susceptibility measurements, FT-IR and electronic spectral studies. The thermal stability and the magnetic sussepcibility of the MOFs were also studied by TGA analyses and Gouy method. These studies show that all the MOFs have octahedral arrangement around the metal ions except vanadium cxcomplex which is distorted square pyramidal geometry. Zeta potential of TPA, TPA–Cr, and TPA–Sb MOFs were shown that formulations have neutral, TPA–In and TPA–V MOFs positive and negative surface charges.

Sol-gel synthesis of Tb-doped hydroxyapatite with high performance as photocatalyst for 2, 4 dichlorophenoxyacetic acid mineralization

BACKGROUND Tb3+doped hydroxyapatite was synthetized by the sol–gel technique, using amounts of the dopant source ranging from 2 to 12 wt%, with respect to the calcium former material. The solids were analyzed using several techniques in order to determine their structural, textural and optical properties. The photoactivity of the materials was tested in the degradation of 2,4-dichlorophenoxyacetic acid, under UV irradiation. RESULTS The analysis of the samples by X-ray diffraction, energy-dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy indicates the formation of hydroxyapatite with calcium deficiency, with a stoichiometry close to the ideal in the sample doped with 10 wt% of terbium. The highest photoluminescence emission, production of •OH radicals under UV in the terephtalic acid reaction, as well as photocatalytic activity in the photodegradation of 2,4-dichlorophenoxyacetic acid (2,4-D) was found in the sample doped with 10 wt% of terbium, reaching almost total degradation and 95% of mineralization of the organic molecule, after 240 min irradiation. CONCLUSION Terbium doping during the synthesis of hydroxyapatite significantly improves its efficiency as photocatalyst. © 2017 Society of Chemical Industry

Correlations between photocatalytic activity and chemical structure of Cu-modified TiO2–SiO2 nanoparticle composites

Copper-modified TiO2–SiO2 photocatalysts were prepared by sol–gel method based on organic copper, silicon and titanium precursors. Copper concentration varied from 0.1 to 3.0mol%. A widely applied model reaction of photocatalytic oxidation of terephtalic acid (TPA) in water solution was used in order to evaluate the catalytic activities of elaborated samples. The crystal structures of the titania components of all tested titania–silica species were studied using XRD analysis. The influence of Cu2+ cation incorporation on the crystal structure of titania, as well as the chemical states and the neighbouring structures of copper cations, have been examined by means of Cu K-edge EXAFS and XANES analysis. The experimental data show that there is a ten times increase in photocatalytic activity when TiO2–SiO2 matrix is modified with 0.1mol% of Cu. It can be supposed that an enhancement of photocatalytic activity of low-concentrated copper-modified titania–silica nanocomposites is probably due to a close attachment of Cu2+ cations to the surfaces of photocatalytically active TiO2 nanoparticles. In this case, Cu2+ cations may possibly act as free electron traps reducing the intensity of recombination between opposite free charge carriers (electrons, holes) available at the photocatalyst’s surface.

Photomineralization of aqueous salicylic acids. Photoproducts characterization and formation of light induced secondary OH precursors (LIS-OH)

The photolysis of aqueous 5-chlorosalicylic acid (ClSA) and dihydroxybenzoic acid (DHBA), its main photoproduct, was studied to determine the extent of degradation caused by simulated solar light. Photoproducts identification was achieved using high resolution LC-MS and GC-MS. About 40 photoproducts from C19 to C1 were characterized, including a dihydroxycyclopentadienic acid, a ring contraction photoproduct, and numerous carbonyls and carboxylic acid derivatives that were detected thanks to derivatization. UV–visible spectral monitoring of the reactions revealed that ClSA and DHBA underwent photobleaching after developing a temporarily featureless absorbance between 300 and 500 nm. Measurement of OH radicals using terephtalic acid as a probe showed that OH radicals were generated with an average rate of 7 × 10−9 M s−1 and a total cumulated concentration of 10−3 M, corresponding to ∼ 5-fold the initial concentration of DHBA. Furthermore, TOC analysis indicated that significant mineralization (51–90%) occurred. These findings are consistent with the formation of light induced secondary OH (LIS-OH) precursors such as featureless long wavelength absorbing compounds as well as non-absorbing hydroperoxides. The formation of LIS-OH illustrated here may also take place in the aqueous photodegradation of other substituted phenols likely present in dissolved organic matter and humic substructures, it deserves to be studied in more details.

Non-metal doped TiO2 nanotube arrays for high efficiency photocatalytic decomposition of organic species in water

Titanium dioxide is a well-known photoactive semiconductor with a variety of possible applications. The procedure of pollutant degradation is mainly performed using TiO2 powder suspension. It can also be exploited an immobilized catalyst on a solid support. Morphology and chemical doping have a great influence on TiO2 activity under illumination. Here we compare photoactivity of titania nanotube arrays doped with non-metal atoms: nitrogen, iodine and boron applied for photodegradation of organic dye - methylene blue and terephtalic acid. The doped samples act as a much better photocatalyst in the degradation process of methylene blue and lead to the formation of much higher amount of hydroxyl radicals (•OH) than undoped TiO2 nanotube arrays. The use of a catalyst active under solar light illumination in the form of thin films on a stable substrate can be scaled up for an industrial application.

Application of sequential expanded granular sludge bed reactors for biodegradation of acetate, benzoate, terephtalate and p-toluate in purified terephtalic acid production wastewater

ABSTRACTThe anaerobic degradation of four major constituents from purified terephtalic acid production wastewater in sequential two expanded granular sludge bed (EGSB) reactors was studied. The performance of the system was evaluated in terms of chemical oxygen demand (COD) removal efficiencies, methane production, stability, granular sludge adaptability as well as reversion of bacterial inhibition. With volumetric loading rates of 1.9–25 kg-COD m−3 d−1 and terephtalate and p-toluate of 584–821 mg L−1, average removal efficiencies of 97.6% and 75.2% were achieved in the EGSB reactors, respectively. In these conditions, gas production reached a total methane production rate of 0.33 L g-COD−1 in the two-stage EGSB reactor system. The disturbance of the EGSB reactors was observed at a feed concentration above around 6.9 g-COD L−1 because of higher influent COD concentration compared to other experiments.