Search

Iron (II) phthalocyanine (FePc) supported on electrospun polyester/poly-4-vinylpyridine nanofibers (PET/P4VP NFs) was prepared by stirring in tetrahydrofuran. The resulting product was confirmed and characterized by ultraviolet-visible diffuse reflectance spectroscopy, attenuated total reflection Fourier transform infrared spectra, X-ray photoelectron spectroscopy, gas chromatography/mass spectrometry, and ultra-performance liquid chromatography. More than 95% of sulfaquinoxalinum (SQX) could be removed by the activation of hydrogen peroxide in the presence of FePc-P4VP/PET with a PET and P4VP mass ratio of 1:1. This system exhibited a high catalytic activity across a wide pH and temperature range. The degradation rates of SQX achieved 100, 95, and 78% at a pH of 3, 7, and 9, respectively, and the degradation rates of SQX are more than 80% at the temperature ranging from 35 to 65 °C. DMSO2 could be detected by gas chromatography/mass spectrometry after the addition of DMSO, suggesting the formation of the high-valent iron intermediates in this catalytic system. In addition, the electron paramagnetic resonance experiments proved that free radicals did not dominate the reaction in our system. Therefore, the high-valent iron intermediates were proposed to the main active species in the FePc-P4VP/PET/hydrogen peroxide system. In summary, the heterogeneous catalytic processes with non-radical catalytic mechanism might have better catalytic performance for the removal of organic pollutants, which can potentially be used in wastewater treatment. [ABSTRACT FROM AUTHOR]

In the field of environmental catalysis, the construction of highly efficient and stable catalytic oxidation processes has raised considerable attention. In this study, a novel solar-initiated photocatalytic oxidation system, FePcCl 16 /PMS/Sunlight, was established by iron hexadecachlorophthalocyanine (FePcCl 16 ) with peroxymonosulfate (PMS) in the presence of sunlight excitation. Under sunlight irradiation, the phthalocyanine ring of the FePcCl 16 is motivated to FePcCl 16 ∗ in the excited state, which activates PMS to generate free radicals or high–valent iron(IV)-oxo intermediates (Fe(IV) = O) to oxidize carbamazepine (CBZ). The system could degrade CBZ effectively and total-organic-carbon removal from solution reached nearly 80% within 90 min. FePcCl 16 catalytic activity was almost without loss and without iron leaching after twenty recycles, indicating that the FePcCl 16 /PMS/Sunlight was a stable and efficient photocatalytic oxidation system. Electron paramagnetic resonance, gas chromatography-mass spectrometry and photocatalytic-activity-experiment analysis shows that Fe(IV) = O species, singlet oxygen ( 1 O 2 ), hydroxyl and sulfate radicals ( OH, SO 4 − ) are the main active species in the catalytic oxidation of CBZ. Density functional theory (DFT) calculations exhibits that the electronic cloud for excited state FePcCl 16 ∗ is transferred from the porphyrazine ring and peripheral substituents to the central Fe atom and its axial position. The main degradation intermediates and possible degradation pathway of CBZ were proposed by ultra-performance liquid chromatography and high-resolution mass spectrometry (UPLC Synapt G2-S HDMS). This study provides efficient catalytic oxidation support for wastewater treatment. [ABSTRACT FROM AUTHOR]

Ordered mesoporous carbon (OMC) materials have received attention for use as supports in highly efficient catalytic systems because of their excellent properties. We used epoxy compound 2,3-epoxypropyl trimethylammonium chloride (EPTAC) to modify cobalt tetraaminophthalocyanine (CoTAPc) and obtained a novel catalyst (OMC-CoTAPc-EPTAC) based on OMC-bonded CoTAPc-EPTAC that could oxidize Acid Red 1 (AR1) dyes by hydrogen peroxide (H2O2) activation under neutral conditions. OMC enhanced the catalytic performance of OMC-CoTAPc-EPTAC, which resulted in the combined high catalytic activity and high stability. Because of its large surface area and tunable pore texture, OMC has high substrate accessibility, and the modification of the catalyst with EPTAC could promote adsorption of the target substrate into OMC, which achieved the aim of in situ catalytic oxidation with enrichment of the target substrate and improved the catalytic efficiency significantly. Electron paramagnetic resonance spin-trap experiments confirmed that the OMC-CoTAPc-EPTAC/H2O2 system had a nonradical catalytic mechanism, and the high-valent cobalt-oxo intermediates and generated holes were speculated to act as dominant oxidation species for the catalytic degradation of AR1. These results demonstrated a new strategy for the elimination of low-concentration organic pollutants. [ABSTRACT FROM AUTHOR]

Cobalt tetraaminophthalocyanine was anchored covalently on carbon fiber using an easy and moderate one-step deamination method to obtain a supported heterogeneous catalyst (CoPc-CF). Studies were conducted to understand the CoPc-CF electrode's electrochemical activity, and some typical organic contaminants including dyes, phenols, and carbamazepine could be removed efficiently in this system. This system exhibited a relatively high electrochemical activity over a wide pH range, and provided a nonradical pathway, which was completely different from the traditional electro-Fenton system. The CoPc-CF electrode has a high electrocatalytic activity over a wide reactant concentration range. Repetitive tests showed that CoPc-CF could maintain a high electrocatalytic activity over several cycles. The content of electrogenerated HO during the electrocatalysis process was determined using a photometric method in which N,N-diethyl-phenylenediamine was oxidized by a peroxidase-catalyzed reaction. The possible reaction mechanism was proposed from an electron paramagnetic resonance spin-trap technique. These results show that the CoPc-CF electrode has potential application in wastewater treatment. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The selective elimination of recalcitrant organic pollutants in high backgrounds of complex constituents has proven a significant challenge. Inspired by the naturally occurring oxidation reactions catalyzed by metalloporphyrin-based enzymes, where the target substrates can be oxidized selectively due to the specific enzyme environment and the axial fifth ligands of metalloporphyrins, we developed a bioinspired catalytic system based on cellulosic fiber-boned cobalt phthalocyanine for capturing and oxidizing dyes by H 2 O 2 activation in the presence of high additive concentrations. In this system, the cellulosic fibers provided the amorphous regions, functioning as cavities in the same manner as the protein backbones of enzymes for the selective accessibility of dyes; cobalt phthalocyanine was introduced as the catalytic entity; and linear alkylbenzene sulfonate (one of the most widespread surfactants in industrial and domestic wastewater) was employed as the fifth ligand to help generate high-valent cobalt-oxo intermediates by the heterolytic cleavage of the peroxide O O bond. According to detailed density functional theory calculations, the spin populations are predominantly located around the cobalt-oxo center, achieving an electrophilic attack on the electron-rich azo bond and the aromatic ring of the target model dyes. [ABSTRACT FROM AUTHOR]

As an almost inexhaustible material with unique and outstanding properties, cellulose presents promising potential in the practical issues. In this study, the cellulose fibers-supported cobalt tetra(2,4-dichloro-1,3,5-triazine)aminophthalocyanine(denoted as Co-TDTAPc-F) catalyst and HO system was introduced for removing organic dyes from aqueous solution with large amounts of dyeing auxiliaries. The model dye (acid red 1, AR1) in a relatively low concentration was removed efficiently with a hydroxyl radical (·OH)-involved mechanism. Due to the inherently excellent performance of cellulose fibers (CFs) such as the controllable surface potential and unique swelling ability in aqueous solution, the catalytic oxidation of AR1 was evidently enhanced in the presence of typical dyeing additives (NaCl and urea). Furthermore, CFs have significantly reduced the alcohol inhibition in traditional ·OH-involved reactions by forming hydrogen bonds with hydroxyl group-containing compounds, just like isopropanol. Consequently, such innately wonderful properties of cellulose carriers allowed Co-TDTAPc-F to be a promising catalyst for removing highly hazardous target pollutants in actual wastewater with large amounts of organic and inorganic compounds. The finding serves as an example of well used excellent performance of cellulose support for better reactions, further leading to a comprehensive understanding and application of cellulose. [ABSTRACT FROM AUTHOR]

Abstract: A nanomaterial-based metallophthalocyanine catalyst (CoTAPc-MWCNTs) was prepared by covalently immobilizing cobalt tetraaminophthalocyanine (CoTAPc) on multiwalled carbon nanotubes (MWCNTs). The decomposition reaction of H2O2 was chosen to investigate the coupled catalytic performance. The results of electron paramagnetic resonance and online electrochemical experiments indicated that the catalytic mechanism of CoTAPc-MWCNTs is different from that of cobalt phthalocyanine molecular catalysts. The catalytic pathway of CoTAPc-MWCNTs involves the following steps: first, electron transfer from CoTAPc to H2O2 occurs through the coordination between the central cobalt ion and H2O2, reducing H2O2 to H2O; second, electrons are transferred from MWCNTs to the oxidized CoTAPc, forming hole-doped MWCNTs; finally, hole-doped MWCNTs accept electrons from H2O2, oxidizing H2O2 to O2. When using N,N-diethyl-1,4-phenylenediamine as a chromogenic substance, one obtained a quantitative estimate of holes injected in MWCNTs, corresponding to 1 hole for about 55 carbon atoms. Furthermore, CoTAPc-MWCNTs exhibit very unusual characteristics of controlled catalysis due to the special hydrophobic surface of the MWCNTs, and can be used as an interfacial catalyst for the determination of H2O2 concentration. [Copyright &y& Elsevier]

Abstract: Thermosensitive polymers with metallophthalocyanine were prepared by immobilizing cobalt tetra(2,4-dichloro-1,3,5-triazine)aminophthalocyanine (Co-TDTAPc) on poly(N-isopropylacrylamide) (PNIPA) and copolymers of N-isopropylacrylamide (NIPA) with acrylamide (AM) (P(NIPA-co-AM)) to obtain Co-TDTAPc–PNIPA and Co-TDTAPc–P(NIPA-co-AM). Examination of the thermosensitive behavior of these polymers showed that the proportion of AM in Co-TDTAPc–P(NIPA-co-AM) had a significant effect on the low critical solution temperature (LCST) in aqueous solution. The LCST of Co-TDTAPc–P(NIPA-co-AM) was adjustable from 34.5°C to 90.0°C by changing the AM molar fraction from 0% to 40%. The copolymers showed a high level of catalytic activity on the oxidation of 2-mercaptoethanol in the homogeneous phase when the reaction temperature was below the LCST, and the copolymers could be precipitated and recovered by heterogeneous separation when the temperature was above the LCST. Compared to Co-TDTAPc–PNIPA, the catalytic system with Co-TDTAPc–P(NIPA-co-AM) is able to maintain homogeneity at a higher temperature due to the higher LCST of the copolymers. In addition, strong salting-out salts, such as NaCl and Na2SO4, can decrease the LCST of the copolymers dramatically and obviate the need for more heat to drive the catalytic reaction system to achieve heterogeneous separation. Co-TDTAPc–P(NIPA-co-AM) was stable and remained efficient during repetitive test cycles with no obvious decrease of catalytic activity. [Copyright &y& Elsevier]

Abstract: Multiwalled carbon nanotubes (MWCNTs) used to support a metallophthalocyanine catalyst (CoTAPc–MWCNTs) were prepared using covalent immobilization of cobalt tetraaminophthalocyanine (CoTAPc) on them, and characterized by X-ray photoelectron spectroscopy, attenuated total reflection Fourier transform infrared spectra and thermogravimetric analysis. The oxidative decoloration of rhodamine 6G (Rh6G) in the presence of CoTAPc–MWCNTs and H2O2 was investigated by examination of UV–Vis absorption spectra. The results showed that Rh6G was oxidized efficiently in the CoTAPc–MWCNTs/H2O2 system. The introduction of MWCNTs resulted in a marked enhanced catalytic activity that CoTAPc does not have. Electron paramagnetic resonance spin-trap experiments indicated that CoTAPc–MWCNTs have a novel non-radical pathway, which is different from common CoTAPc catalytic systems. Furthermore, the result of online electrochemical measurement in the CoTAPc–MWCNTs/H2O2 system suggested that MWCNTs might participate directly in the electron transfer process in the catalytic oxidation of this conjugated dye. In this catalytic system, MWCNTs provide strong adsorption to conjugated Rh6G due to their special sp2-hybridized surface, and are able to rapidly oxidize the conjugated dye by a special electron transfer pathway. [Copyright &y& Elsevier]

Abstract: We have developed a novel heterogeneous metallophthalocyanine catalyst, Co-TDTAPc–ACF, by immobilizing cobalt tetra(2,4-dichloro-1,3,5-triazine)aminophthalocyanine (Co-TDTAPc) on activated carbon fiber (ACF) covalently. The oxidative removal of 4-nitrophenol (4-NP) in the Co-TDTAPc–ACF/H2O2 system, based on phase transfer catalytic oxidation, was investigated in aqueous solution by ultra-performance liquid chromatography (UPLC). The results indicated that 4-NP could be removed efficiently by catalytic oxidation in the presence of Co-TDTAPc–ACF and H2O2. In addition, the removal of total organic carbon of 4-NP accounted for about 90% in 300min of reaction. Gas chromatography/mass spectrometry (GC–MS) analysis showed that the residue products were mainly small molecular compounds such as maleic acid and succinic acid, etc. This system exhibited high catalytic activity across a wide pH and temperature range. Importantly, compared with homogeneous Co-TDTAPc used alone, the introduction of ACF contributed specifically to the activity enhancement of Co-TDTAPc. Controlled experiments showed that the presence of 2-propanol, as hydroxyl radicals scavenger, has little influence on 4-NP oxidation. The further result of electron paramagnetic resonance (EPR) spin-trap experiments indicated that free radicals did not dominate the reaction in our system. This paper discusses a possible catalytic oxidation mechanism of the Co-TDTAPc–ACF/H2O2 system. Repetitive tests showed that Co-TDTAPc–ACF can maintain high catalytic activity over several cycles, and it has a better regeneration capability under mild conditions. We conclude that phase transfer catalytic oxidation has proven itself to be a feasible approach which may be potentially applied to the elimination of widely existing pollutants. [Copyright &y& Elsevier]

Recently, peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs) have received increasing attention because of their capability and adaptability in decontamination. The couple of solar light and PMS activation is an environmentally friendly and efficient strategy for environmental remediation. Herein, the iron hexadecachlorophthalocyanine (FePcCl 16 ) was used to coordinate with graphitic carbon nitride (g-C 3 N 4 ), which was functionalized by pyridine-based ligand isonicotinic acid (INA) to prepare a distinctive catalyst, g-C 3 N 4 -INA-FePcCl 16 . The experimental results revealed that g-C 3 N 4 -INA-FePcCl 16 can activate PMS efficiently for the elimination of carbamazepine (CBZ) under visible light irradiation over a wide pH range. Upon irradiation with visible light, CBZ was destroyed by the solider g-C 3 N 4 with generated sulfate (SO 4 − ) and hydroxyl ( OH) radicals, on the other hand, high-valent iron (Fe (IV) = O) species accompanied by SO 4 − and OH radicals were produced by excited-state FePcCl 16 (*FePcCl 16 ) during oxidation, which is different from a traditional PMS activation system. The axial pyridine-based ligand was protected under the FePcCl 16 macrocyclic structure shield. Noteworthy, in the absence of visible light, g-C 3 N 4 -INA-FePcCl 16 showed a higher catalytic performance than pure g-C 3 N 4 , FePcCl 16 and a mechanical mixture of the two. This study allows for the construction of an effective and environmental catalytic system, which can be applied to purify water that contains refractory pollutants. [ABSTRACT FROM AUTHOR]

Iron (II) phthalocyanine (FePc) molecules were isolated in polyacrylonitrile (PAN) nanofibers by electrospinning to prevent the formation of dimers and oligomers. Carbamazepine (CBZ) and Rhodamine B (RhB) degradation was investigated during a Fenton-like process with FePc/PAN nanofibers. Classical quenching tests with isopropanol and electron paramagnetic resonance tests with 5,5-dimethyl-pyrroline-oxide as spin-trapping agent were performed to determine the formation of active species during hydrogen peroxide (H 2 O 2 ) decomposition by FePc/PAN nanofibers. After eight recycles for CBZ degradation over the FePc/PAN nanofibers/H 2 O 2 system, the removal ratios of CBZ remained at 99%. Seven by-products of RhB and twelve intermediates of CBZ were identified using ultra-performance liquid chromatography and high-resolution mass spectrometry. Pathways of CBZ and RhB degradation were proposed based on the identified intermediates. As the reaction proceeded, all CBZ and RhB aromatic nucleus intermediates decreased and were transformed to small acids, but also to potentially toxic epoxide-containing intermediates and acridine, because of the powerful oxidation ability of • OH in the catalytic system. [ABSTRACT FROM AUTHOR]

Two different nanomaterial-based metallophthalocyanine catalysts were synthesized by immobilizing iron trinitrophthalocyanine with amino (FeMATNPc) covalently on multi-walled carbon nanotubes (MWCNTs) by deamination-synthesized MWCNTs-FeTNPc and on oxidized MWCNTs by amidation-synthesized MWCNTs–CONH–FeTNPc. The resulting hybrid structure was confirmed and characterized by X-ray photoelectron spectroscopy and attenuated total reflection Fourier transform infrared spectra. Catalytic activity tests showed that the introduction of MWCNTs resulted in a marked enhanced catalytic activity of FeMATNPc. A series of designed experiments proved that large amounts of hydroxyl radicals accompanied by some peroxy radicals and seldom by high-valent iron intermediates were formed in a MWCNTs-FeTNPc/H 2 O 2 system. In a MWCNTs–CONH–FeTNPc/H 2 O 2 system, much more high-valent iron intermediates with fewer hydroxyl radicals were formed. Conduction electron spin resonance and cyclic voltammetry was used to investigate the intrinsic difference between the two catalysts. More conducting electrons fill MWCNTs and electron transfer between MWCNTs and iron phthalocyanine is faster than that for MWCNTs–CONH–FeTNPc. This special electronic property may influence the formation of active species. [ABSTRACT FROM AUTHOR]

The design of catalytic oxidation processes with high efficiency has attracted considerable attention for a long while in environmental catalysis. In this work, a novel oxidation system, CFs-CoPc/PMS, was developed by coupling cellulosic fibers-bonded cobalt phthalocyanine (CFs-CoPc) with peroxymonosulfate (PMS). CFs-CoPc/PMS system could effectively decolorize azo dyes such as Acid Red 1 (AR1) with almost 100% decolorization efficiency in 35 min, suggesting that the CFs-CoPc/PMS system was a highly efficient oxidation process. In addition, bicarbonate ion (HCO 3 − ) was further introduced to CFs-CoPc/PMS to construct a combined system, CFs-CoPc/PMS/HCO 3 − . Remarkably, this system turned the negative effect of HCO 3 − observed in most reported Co/PMS systems into a positive one, which enhanced the AR1 decolorization with over 2-fold increase of the rate constant. The main factor responsible for the enhancement was high-valent cobalt-oxo intermediates (PcCo IV = O), which was presumably generated via the heterolytic cleavage of the PMS OO bond by CoPc-HCO 3 − complex. It is noteworthy that high-valent cobalt-oxo intermediates as the major active species is different from most reported mechanisms in Co/PMS systems, in which hydroxyl and sulfate radicals are recognized as the dominant active species. This study paves an avenue for developing highly efficient catalytic oxidation technology for wastewater remediation. [ABSTRACT FROM AUTHOR]

Abstract: Zinc phthalocyanine (ZnPc) modified by cyanuric chloride was supported on TiO2–SiO2 microparticles (ZnPc–SiO2–TiO2) by covalent bonds to produce a novel photosensitizer, ZnPc–SiO2–TiO2. ZnPc sensitized TiO2 to light in the visible range, while the TiO2 acted as an acceptor of electrons generated by the photon irradiation; thus, this material can absorb low-energy photons to emit photons of higher energy. The as-prepared ZnPc–SiO2–TiO2 was characterized using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and UV–vis diffuse reflectance spectroscopy (DRS). The results of photodecomposing methylene blue (MB) revealed that ZnPc–SiO2–TiO2 had great photocatalytic activity under visible-light irradiation (λ>400nm). By analyzing electron paramagnetic resonance (EPR) spectra, we proposed a possible mechanism for the photodecomposition of MB by ZnPc–SiO2–TiO2. [Copyright &y& Elsevier]

Abstract: Zinc tetraaminophthalocyanine (Zn-TAPc) modified by cyanuric chloride was immobilized on silk fibers by covalent bond to obtain a supported photocatalyst (Zn-TDTAPc-SF). The photocatalytic degradation of acid orange II based on Zn-TDTAPc-SF/O2 system was investigated under visible light irradiation (λ ≥ 400 nm). The results indicated that Zn-TDTAPc-SF exhibited excellent photocatalytic performance in the presence of O2 under visible light irradiation. In 6 h, more than 93% of acid orange II (AO2) in Zn-TDTAPc-SF/O2 system was eliminated at initial pH 5 under visible light irradiation, and Zn-TDTAPc-SF still remained effective in repetitive fives cycles. Furthermore, NaCl played a positive role in the catalytic reaction, different from the negative one observed in homogeneous catalysis, and the reaction can proceed in a more wide pH range from acidic to alkaline. Based on the analysis of FT-IR and Gas Chromatography/Mass Spectrometry (GC–MS), AO2 was mainly converted into some small molecular biodegradable aliphatic carboxylic compounds such as maleic acid, fumaric acid, succinic acid, etc. The photodegradation mechanism for the evolution of AO2 was proposed by Electron Paramagnetic Resonance (EPR) spectra. [Copyright &y& Elsevier]