Sulphonated phthalocyanines as effective oxidation photocatalysts for visible and UV light regions

Exploring the viability of a floating photocatalyst in a continuous stirred tank reactor system for continuous water treatment

The use of photocatalysts in continuous stirred tank reactor (CSTR) systems allows for efficient and continuous water treatment, thus meeting the demand for scalable technology and comparative data in large-scale implementations. Hence, this study aims to explore the feasibility of a floating photocatalyst within a CSTR system for continuous water treatment. An expanded polystyrene (EPS)-TiO2 composite was synthesized following established methodologies, and their efficacy in removing the water pollutant methylene blue (MB) was compared for both batch and CSTR systems. A nonlinear first-order model was identified as the most suitable approach to accurately simulate MB degradation under experimental conditions, and the calculated pseudo-first-order degradation rate constant (k') for the CSTR system (0.0126-0.0172/min) was found to be superior to that observed for the batch system (0.0113/min). In addition, an increase in the flow rate reduced the retention time, leading to lower MB removal efficiency for the CSTR system. In addition, the EPS-TiO2/UV system with a CSTR configuration was found to efficiently use light and energy based on the calculated quantum yield (Φ = 2.86 × 10-4) and electrical energy per order (EEO = 857.46 kWh/m3/order). The findings of this study contribute to the development of sustainable and efficient water treatment strategies, offering valuable insight into the implementation of practical water treatment processes.

Chemical and Electronic Structure Characterization of Electrochemically Deposited Nickel Tetraamino-phthalocyanine: A Step toward More Efficient Deposition Techniques for Organic Electronics Application

Phthalocyanines (Pc), with or without metal ligands, are still of high research interest, mainly for the application in organic electronics. Because of rather low solubility, Pc-based films are commonly deposited applying various advanced and demanding vacuum techniques, like physical vapor deposition (PVD). In this work, an alternative straightforward approach of NiPc layer formation is proposed in which NH₂-side groups of nickel(II) tetraamino-phthalocyanine (AmNiPc) are engaged in the process of electrochemical deposition of (AmNiPc)_layer on indium-tin oxide (ITO) substrates. The resulting layer is widely investigated by cyclic voltammetry, atomic force microscopy, UV-vis, and ATR-IR spectroscopies, X-ray diffraction, and photoemission techniques: X-ray and UV-photoelectron spectroscopies. The chemical and electronic structure of (AmNiPc)_layer is characterized. It is shown that the electronic properties of the formed (AmNiPc)_layer/ITO hybrid correspond to the ones previously reported for PVD-NiPc films.

Iron phthalocyanine-sensitized magnetic catalysts for BPA photodegradation

The catalytic behavior of iron phthalocyanine (FePc)-sensitized magnetic nanocatalysts was evaluated for their application in the oxidative treatment of Bisphenol A (BPA) under mild environmental conditions. Two types of FePc (Fe(II)Pc and Fe(III)Pc), which are highly photosensitive compounds, were immobilized on the surface of functionalized magnetite. The nanomaterials were characterized by high resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analyses (TGA). The generation of singlet oxygen by nanomaterials was also investigated. In the presence of UVA light exposure (365 nm) and 15 mM H₂O₂, the M@Fe(III)Pc photocatalyst gave the best results; for a catalyst concentration of 2.0 g L ^− 1, around 60% BPA was removed after 120 min of reaction. These experimental conditions were further tested under natural solar light exposure, for which also M@Fe(III)Pc exhibited enhanced oxidative catalytic activity, being able to remove 83% of BPA in solution. The water samples were less cytotoxic after treatment, this being confirmed by the MCF-7 cell viability assay.

Photophysical and nonlinear optical study of benzothiazole substituted phthalocyanines in solution and thin films

In this study, the photophysical, nonlinear absorption and nonlinear optical limiting properties of zinc and gallium phthalocyanine complexes: tetrakis[(benzo[d]thiazol-2-yl phenoxy)phthalocyaninato]zinc(II) (3), tetrakis[(benzo[d]thiazol-2-yl phenoxy)phthalocyaninato] gallium(III) chloride (4), tetrakis[(benzo[d]thiazol-2-ylthio)phthalocyaninato] zinc(II) (5), tetrakis[(benzo[d]thiazol-2-ylthio)phthalocyaninato] gallium(III) chloride (6), were investigated both in solution and when embedded in polystyrene thin films using 532 nm laser excitation at 10 ns pulses. It was also observed that complexes that have higher triplet state absorption also possessed enhanced nonlinear and optical limiting behavior. Superior optical performance was observed when the complexes were embedded in thin films compared to when they are in solution. Complex 6 in thin films gave the highest imaginary third-order susceptibility (I[Formula: see text][X[Formula: see text]]) and hyperpolarizability ([Formula: see text] at 4.61 × 10[Formula: see text] esu and 3.44 × 10[Formula: see text] esu, respectively, with a low I[Formula: see text] value of 0.06 J.cm[Formula: see text]

A review of iron species for visible-light photocatalytic water purification

Iron species are one of the least toxic and least expensive substances that are photocatalytic in the visible region of the spectrum. Therefore, this article focuses on iron-based photocatalysts sensitive to visible light. Photo-Fenton reactions are considered with respect to those assisted by and involve the in situ production of H₂O₂. The possible role that photoactive iron species play by interacting with natural organic matter in water purification in the natural environment is considered. The review also considered photosensitization by phthalocyanines and the potential role that layered double hydroxides may have not only as catalyst supports but also as photosensitizers themselves. Finally, photocatalytic disinfection of water is discussed, and the desirability of standardized metrics and experimental conditions to assist in the comparative evaluation of photocatalysts is highlighted.

Mesopolymer modified with palladium phthalocyaninesulfonate as a versatile photocatalyst for phenol and bisphenol A degradation under visible light irradiation

A novel versatile photocatalyst, FDU-PdPcS, was prepared by immobilizing palladium phthalocyaninesulfonate (PdPcS) onto the FDU-15 mesopolymer via multi-step chemical modification processes involving chloromethylation of the FDU-15 mesopolymer first with chloromethyl methyl ether, a subsequent amination reaction with ethylenediamine, and finally modification with palladium phthalocyaninesulfonate via ionic interaction. The obtained FDU-PdPcS photocatalyst was characterized by the X-ray diffraction (XRD), UV-Vis spectrosopy and inductively coupled plasma (ICP) techniques. This photocatalyst not only affords a high dispersion of monomeric PdPcS molecules, which may further be stabilized by the pi-electron of benzene rings of FDU-15, but also provides a number of diamino groups inside the mesopores, which could be advantageous for the photodegradation of phenolic pollutants. In photodegradation studies of phenolic pollutants, the FDU-PdPcS catalyst exhibited excellent visible light photocatalytic activity and reusability. The photodegradation products of phenol and bisphenol A were investigated by the gas chromatoghraphy-mass spectrometry (GC-MS) technique. The results showed that the photodegradation products were composed of carboxylic acids and CO2. Isopropanol, sodium azide and benzoquinone were used as hydroxyl radical (OH*), singlet oxygen (1O2) and superoxide radical (O2*-) scavengers, respectively. The results suggested that 1O2 and O2*- were the prominent active species during the photodegradation process. A possible mechanism for the photodegradation of phenol was also discussed.

Catalytic Activity of Tetranitro-Copper Phthalocyanine Supported on Carbon Nanotubes towards Oxygen Reduction Reaction

Acid-functionalized multiwalled carbon nanotube (AF-MWCNT)-supported tetranitro-copper phthalocyanine (TNCuPc) assemblies were prepared by solid phase synthesis method. The products were characterized by infrared spectroscopy, scanning electron microscopy and XRD. The electrocatalytic activity of the obtained AF-MWCNT-supported TNCuPc assemblies was measured by cyclic voltammetry (CV) and rotating disk electrode (RDE) techniques in an oxygen-saturated 0.1 M KOH. The results showed that the catalytic activity of TNCuPc/AF-MWCNTs towards oxygen reduction was a two-step, two-electron process for oxygen reduction.

Efficient removal of dyes in water using chitosan microsphere supported cobalt (II) tetrasulfophthalocyanine with H2O2

A new efficient catalyst, CoTSPc@chitosan, was developed by immobilizing water soluble cobalt (II) tetrasulfophthalocyanine onto adsorbent chitosan microspheres covalently for the heterogeneous catalytic oxidation of C. I. Acid Red 73 with H(2)O(2). The result indicated that the COD removal and discoloration of C. I. Acid Red 73 made 55 and 95% respectively in the presence of CoTSPc@chitosan with H(2)O(2) in 4h. In addition, CoTSPc@chitosan-H(2)O(2) system could proceed efficiently in a relatively wide pH range and remain high catalytic activity after 6 reuse cycles. Furthermore, the adsorption study of CoTSPc@chitosan confirmed that chitosan was an outstanding support which contributed a lot to the removal reaction. In conclusion, the combination of adsorption process and catalytic oxidation made the CoTSPc@chitosan-H(2)O(2) system achieve a simple, efficiently and environmentally friendly water treatment.

Preparation of magnetic silica nanoparticle-supported iron tetra-carboxyl phthalocyanine catalyst and its photocatalytic properties

Iron tetra-carboxyl phthalocyanine (TCFePc) was covalently immobilized to the surface of core-shell magnetite silica nanoparticles (NPs) as facilely separated supported catalyst, namely P-M SiO(2) NPs, for catalyzing the degradation of organic pollutants in aqueous solution under visible light irradiation. X-ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy (SEM), superconducting quantum interference device (SQUID), and ultraviolet-visible (UV-Vis) spectroscopy were used to characterize the sample. The photocatalytic activity of P-M SiO(2) NPs was determined using rhodamine B (RhB) and methyl orange (MO) as the objective decomposition substances. The results revealed that the novel supported catalyst exhibited good catalytic activity over a wide pH range, and the degradation rate of RhB and MO is up to 90% during 120 min of reaction. Moreover, it is noteworthy that the catalyst can be easily separated using an external magnetic field and employed directly for the next round of reaction.

Sulphonated cobalt phthalocyanine-MCM-41: an active photocatalyst for degradation of 2,4-dichlorophenol

The photocatalytic activity of sulphonated cobalt phthalocyanine immobilized onto MCM-41 was investigated for decomposition of 2,4-dichlorophenol (2,4-DCP) in aqueous solutions. Immobilization of anion sulpho-cobalt phthalocyanine to the walls of MCM-41 was performed by pre-anchorage of 3-(aminopropyl)-triethoxysilane (APTES) onto MCM-41 via post-synthesis method. X-ray diffraction, nitrogen physisorption, diffuse reflectance spectroscopy, energy-dispersive X-ray and FT-IR methods were used to characterize the product. Photocatalytic efficiency of the prepared catalyst for degradation of 2,4-DCP was tested under illumination of UV-A and visible light. The results obtained reveal that the photocatalyst is very active in degradation of 2,4-DCP. The photodegradation process is completed within 3h using a dose of 0.6g/L of the catalyst under UV irradiation. The reactions follow a pseudo-first-order kinetics and the observed rate constant values change with 2,4-DCP concentrations. The reproducibility of the catalyst was tested. The reaction intermediates were identified by gas chromatoghraphy-mass spectrometry (GC-MS) technique.

Photophysical properties and photodynamic activity of octacationic oxotitanium(IV) phthalocyanines

The photophysical and photosensitizing properties of two octacationic oxotitanium phthalocyanines (TiOPcs), bearing pyridiniomethyl or cholinyl substituents, have been studied in aqueous and alcohol solutions. In water, both compounds were monomeric with the high quantum yields of fluorescence (Phi(F) = 0.17-0.19) and singlet oxygen formation (Phi(Delta) = 0.4-0.5). The Phi(F) and Phi(Delta) of both phthalocyanines decreased with the increase of solvent hydrophobicity from water to ethanol. This effect was much stronger in alcohol solutions of the pyridiniomethyl-substituted phthalocyanine and probably results from aggregation of TiOPc molecules caused by association of chloride anions with phthalocyanine cationic groups. Evidence is presented that under illumination aqueous TiOPc solutions also produce hydroxyl radicals, which probably appear owing to photocleavage of water molecules. The quantum yield of OH formation was (3-5) x 10(-5) after argon purging and twice as much in the presence of air. It is shown that irradiation of TiOPc solutions causes photobleaching of TiOPcs. The photobleaching quantum yield in water was found to be about 1 x 10(-4). The data suggest that photobleaching occurs owing to the reactivity of hydroxyl radicals, though singlet oxygen is generated by TiOPcs much more efficiently. The phototoxicity of the tested TiOPcs toward bacteria has been revealed. It is proposed that both OH and (1)O(2) might be responsible for the observed bactericidal effects.

Low-temperature preparation and characterization of iron-ion doped titania thin films

Iron-ion doped titania thin films with an anatase phase were successfully synthesized in this study using the high-pressure crystallization (HPC) process. The crystallization temperature of Fe(3+)-doped TiO(2) thin films was markedly reduced to be as low as 125 degrees C. The films prepared via the HPC process have a more uniform microstructure and smaller grain sizes than the films prepared via the atmospheric-pressure annealing process. The films prepared via both processes were found to have photocatalytic properties under visible light. The films prepared via the HPC process exhibited enhanced photocatalytic activities in comparison with the films annealed via the conventional process. Increasing the annealing temperature in the HPC process resulted in an improvement in the photocatalytic properties because of an increase in the crystallinity of the prepared films. The HPC process was demonstrated to be a potential method for synthesizing visible-light driven titania thin films with enhanced photocatalytic activities at low temperatures.