Complete Degradation Of Methylene Blue Research Articles

Upcycling waste derived glass into high-performance photocatalytic scaffolds by alkali activation and direct ink writing

Novel and eco-friendly solutions are extensively needed for wastewater treatment. This work capitalizes on the combination of waste vitrification and additive manufacturing to produce an efficient photocatalyst for the specific purpose. Fine powders of waste-derived glass, containing Fe3O4 inclusions, by simple suspension (for a solid loading of 65 wt %) in alkaline solution (5 M NaOH), were transformed into pastes for direct ink writing. 3D-printed reticulated scaffolds were stabilized by the progressive hardening of a zeolite-like gel, formed by glass/solution interaction, at nearly room temperature. The printed scaffolds were successfully tested for the removal of methylene blue, realized by combining the high sorption capacity of the gel with the catalytic activity of magnetite inclusions, under UV light. A complete degradation of methylene blue is achieved by 90 min exposure, comparing favorably with other reported photocatalytic materials, requiring from 60 to 360 min. The photocatalytic activity was tested for several cycles, with no significant degradation. In other words, a waste-derived material can be reused for multiple times, to remediate wastewaters, with evident benefits on waste minimization.

Versatile Application of TiO2@PDA Modified Filter Paper for Oily Wastewater Treatment

Although membrane separation technology has been widely used in the treatment of oily wastewater, the complexity and high cost of the membrane preparation, as well as its poor stability, limit its further development. In this study, via the vacuum-assisted suction filtration method, polydopamine (PDA)-coated TiO2 nanoparticles were tightly attached and embedded on both sides of laboratory filter paper (FP). The resultant FP possessed the typical wettability of high hydrophilicity in the air with the water contact angle (WCA) of 28°, superoleophilicity with the oil contact angle (OCA) close to 0°, underwater superoleophobicity with the underwater OCA greater than 150°, and superhydrophobicity under the water with the underoil WCA over 150° for five kinds of organic solvents (carbon tetrachloride, toluene, n-hexane, n-octane, and iso-octane). The separation efficiency of immiscible oil/water, oil-in-water, and water-in-oil emulsions using the modified FP is higher than 99%. After 17 cycles of emulsion separation, a high separation efficiency of 99% was still maintained for the FP, along with good chemical and mechanical stability. In addition, successful separation and purification were also realized for the oil-in-water emulsion that contained the methylene blue (MB) dye, along with the complete degradation of MB in an aqueous solution under UV irradiation.

Enhancing Visible-Light Photocatalysis with Pd(II) Porphyrin-Based TiO2 Hybrid Nanomaterials: Preparation, Characterization, ROS Generation, and Photocatalytic Activity

Novel hybrid TiO2-based materials were obtained by adsorption of two different porphyrins on the surface of nanoparticles—commercially available 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) and properly modified metalloporphyrin—5,10,15,20-tetrakis(2,6-difluoro-3-sulfophenyl)porphyrin palladium(II) (PdF2POH). The immobilization of porphyrins on the surface of TiO2 was possible due to the presence of sulfonyl groups. To further elevate the adsorption of porphyrin, an anchoring linker—4-hydroxybenzoic acid (PHBA)—was used. The synthesis of hybrid materials was proven by electronic absorption spectroscopy, dynamic light scattering (DLS), and photoelectrochemistry. Results prove the successful photosensitization of TiO2 to visible light by both porphyrins. However, the presence of the palladium ion in the modifier structure played a key role in strong adsorption, enhanced charge separation, and thus effective photosensitization. The incorporation of halogenated metalloporphyrins into TiO2 facilitates the enhancement of the comprehensive characteristics of the investigated materials and enables the evaluation of their performance under visible light. The effectiveness of reactive oxygen species (ROS) generation was also determined. Porphyrin-based materials with the addition of PHBA seemed to generate ROS more effectively than other composites. Interestingly, modifications influenced the generation of singlet oxygen for TPPS but not hydroxyl radical, in contrast to PdF2POH, where singlet oxygen generation was not influenced but hydroxyl radical generation was increased. Palladium (II) porphyrin-modified materials were characterized by higher photostability than TPPS-based nanostructures, as TPPS@PHBA-P25 materials showed the highest singlet oxygen generation and may be oxidized during light exposure. Photocatalytic activity tests with two model pollutants—methylene blue (MB) and the opioid drug tramadol (TRML)—confirmed the light dose-dependent degradation of those two compounds, especially PdF2POH@P25, which led to the virtually complete degradation of MB.

Single-step solvothermal synthesis of sepiolite-CoFe2O4 nanocomposite as a highly efficient heterogeneous catalyst for photo Fenton-like reaction

In present research, a novel sepiolite-CoFe2O4 (Sep-CoFe2O4) catalyst was prepared using a facile solvothermal strategy. The structure, morphology, and photoelectric properties of the synthesized catalyst were explored by the SEM, TEM, VSM, DRS, XRD, XPS and EDX methods. The results showed that CoFe2O4 particles had a spherical shape and was successfully deposited on the fibrous structure of Sep clay. The prepared Sep-CoFe2O4 catalyst was employed in heterogeneous photo-Fenton reaction for methylene blue (MB) degradation. Sep effectively prevented the aggregation of CoFe2O4 and clearly enhanced the efficiency of the heterogeneous catalyst for degradation of MB under visible light irradiation. In photo Fenton-like reaction, complete degradation of MB (C = 10 ppm) was achieved in 150 min at mild pH value. The reusability experiments showed that the suggested catalyst can be reused after five successive cycles. Besides, a possible degradation mechanism using the photo Fenton-like system was presumed. Accounting for the high catalytic capability, low cost, as well as good chemical stability, the Sep-CoFe2O4 has great potential working as a heterogeneous photo-Fenton catalyst for degradation of organic contaminants.

Study of enhancing photocatalytic activity of solvothermal grown MoS2 nanocrystals under visible light irradiation by the influence of hydrogen peroxide

In this article, two-dimensional molybdenum sulfide has been synthesized by simple and conventional solvothermal methods and the combined effect of MoS2 nanocrystals and hydrogen peroxide in photocatalytic degradation of methylene blue (MB) in water has been investigated under visible light. Synthesized MoS2 nanocrystals have been characterised by FEG-TEM, FE-SEM, XRD, Raman, FTIR, UV–Vis absorption, PL and TCSPC studies. FEG-TEM and FE-SEM images confirm nanosheets/nanoflowers like morphology and Raman & XRD patterns confirm the 2H-MoS2 phase. Layer-dependent absorption spectra and its Tauc plot were studied and the calculated band gap are found to be 1.73 eV and 1.43 eV for a few layers, bulk MoS2 respectively. This layer-dependent band gap energy is also verified by calculating electronic band structure for mono-layer, bi-layer and bulk MoS2 through density functional theory (DFT). The calculated average lifetime of in MoS2 is 1.5 ns. The kinetic study of the degradation of MB dye with MoS2 in the presence of H2O2 showed complete degradation of MB within 20 min. Whereas, pure MoS2 and H2O2 showed 28.27 % and 89.2 % degradation of MB within 210 min time intervals respectively. Thus, these results show MoS2 has good photocatalytic activity in the presence of H2O2.

Photocatalytic performance of Ag/TiO2/SiO2 nanocomposite synthesized by eco-friendly pulsed laser ablation technique

Sequestration of organic pollutants using nano-photocatalysts is considered an efficient and cost-effective approach for wastewater treatment. Here, Ag/TiO2/SiO2 nanocomposites containing different loads of Ag (0%, 1% and 3%) were prepared using a laser ablation technique. The Ag nanoparticles were synthesized using A Q-switched laser beam of 1064 nm, 60 mJ pulse energy, and the Ag/TiO2/SiO2 was obtained with a focused laser beam at 355 nm and 120 mJ. The obtained nanostructures were analyzed with TEM, SEM, EDX, XRD, BET surface area, Raman, and UV–Vis spectroscopy. Methylene blue (MB) dye was selected to evaluate the photocatalytic performance of the nanocomposites. Generally, the Ag-decorated nanocomposites offer more effective MB degradation than TiO2/SiO2 under UV-light irradiation. Interestingly, virtually complete degradation of MB was recorded with Ag/TiO2/SiO2 (1%). The superior activity shown by the Ag/TiO2/SiO2 with respect to TiO2/SiO2 could be ascribed to the enhanced separation of photogenerated electron/hole pairs induced by Ag. This study establishes the feasibility of laser ablation in fabricating excellent-performing photocatalytic materials.

Synthesis of tetragonal SnO2 photocatalyst for Micro‐structural analysis and visible light driven Fenton‐like degradation of Methylene Blue

AbstractThe present study reports a simple co‐precipitation followed by solid state method for the synthesis of tetragonal SnO2 nanoparticles.The nanoparticles were characterized by XRD, FTIR, SEM, DLS, UV‐vis, and PL techniques to examine the structural properties, functional group, morphological and electronic properties. As prepared SnO2 NPs has been used for Fenton‐like degradation of Methylene blue(MB) in presence of solar light in aqueous solution.The structural analysis and Rietveld refinement revealed that the tetragonal SnO2 NPs have been well formed. The mean crystallite size of the synthesized nanoparticles was found to be 16.47 nm using the Scherrer formula.The Williamson‐Hall method determines strain throughout the crystal. The effect of various parameters such as catalyst dose, dye concentration, H2O2 concentration, pH and temperature was examined.The complete degradation of MB was obtained at pH=9. The results obtained from kinetics showed that degradation of MB dye follows pseudo‐first order rate with the rate constant k1 is 7.889×10−2 min−1. From Brunauer‐Emmet‐Teller (BET) surface analysis, we have determined the surface area and average pore size of SnO2 NPs. All parameters were measured by Brunauer‐Emmet‐Teller (BET) surface analysis with nitrogen adsorption‐desorption isotherm.The pore volume and pore diameter was calculated by BJH (Barrett‐Joyner‐Halenda) model.

Modification of sludge biochar by MnO2 to degrade methylene blue: Synergistic catalysis and degradation mechanisms

In this study, sludge biochar (SBC) was prepared by pyrolysis method, MnO2 and MnO2@SBCs with different MnO2/SBC mass ratios (3%, 5%, 10% and 20%) were synthesized by co-precipitation method. The catalytic performance was examined by activating peroxymonosulfate (PMS) for methylene blue (MB) degradation. MB can be completely removed within 30 min when the mass ratio of MnO2/SBC is greater than 5% and the degradation kinetics of MB is more in line with the pseudo-first-order kinetic model in the MnO2@SBC/PMS system. Besides, the pseudo-first-order kinetic constants (k) in MnO2@SBC/PMS are significantly higher than that in SBC/PMS and MnO2/PMS, and the largest degradation rate of MB is in 5% MnO2@SBC/PMS system. MnO2@SBC exhibited excellent PMS activation ability in a wide range of pH (5–9) with complete degradation of MB in 30 min. Furthermore, MnO2@SBC has good stability after five usages still activating PMS for complete degradation of MB in 180 min. The quenching experiments and EPR spectrum indicated that both SO4−, OH and 1O2 were the main reactive oxygen species. Finally, the probable MB degradation pathway was proposed in the MnO2/PMS system. This study provides a reliable insight into sludge resource utilization, sludge biochar modification and its catalytic performance improvement.

Photocatalytic degradation of methylene blue using ZnO supported on wood waste-derived activated carbon (ZnO/AC)

This study reports the preparation of ZnO supported on wood waste-derived activated carbon (ZnO/AC) and its activity towards photocatalytic degradation of methylene blue (MB). The removal of MB is imperative owing to its toxic impacts on the receiving water bodies. Thus, finding treatment techniques with criteria of efficient, cost-effective, and environmentally benign is highly needed. ZnO/AC has been synthesized by the incipient wetness impregnation method and was characterized using XRD, FTIR, PL, and UV–Vis-NIR. Characterization analysis revealed the successful impregnation of ZnO onto the AC. The best photocatalytic degradation of MB using ZnO/AC was achieved at 180 min, adsorbent dosage of 3 g/L, and pH 8. Complete MB degradation was attained at lower initial MB concentrations (10 – 50 mg/L) and slightly decreased at higher initial MB concentration (100 mg/L). The experimental data fitted well with the pseudo-first-order Langmuir-Hinshelwood kinetic model with a correlation coefficient (R2) greater than 0.995. The results revealed that the synthesized ZnO/AC exhibited remarkable photocatalytic activity towards the degradation of MB.

Statistical modeling of methylene blue degradation by yeast-bacteria consortium; optimization via agro-industrial waste, immobilization and application in real effluents

The progress in industrialization everyday life has led to the continuous entry of several anthropogenic compounds, including dyes, into surrounding ecosystem causing arduous concerns for human health and biosphere. Therefore, microbial degradation of dyes is considered an eco-efficient and cost-competitive alternative to physicochemical approaches. These degradative biosystems mainly depend on the utilization of nutritive co-substrates such as yeast extract peptone in conjunction with glucose. Herein, a synergestic interaction between strains of mixed-culture consortium consisting of Rhodotorula sp., Raoultella planticola; and Staphylococcus xylosus was recruited in methylene blue (MB) degradation using agro-industrial waste as an economic and nutritive co-substrate. Via statistical means such as Plackett–Burman design and central composite design, the impact of significant nutritional parameters on MB degradation was screened and optimized. Predictive modeling denoted that complete degradation of MB was achieved within 72 h at MB (200 mg/L), NaNO3 (0.525 gm/L), molasses (385 μL/L), pH (7.5) and inoculum size (18%). Assessment of degradative enzymes revealed that intracellular NADH-reductase and DCIP-reductase were key enzymes controlling degradation process by 104.52 ± 1.75 and 274.04 ± 3.37 IU/min/mg protein after 72 h of incubation. In addition, azoreductase, tyrosinase, laccase, nitrate reductase, MnP and LiP also contributed significantly to MB degradation process. Physicochemical monitoring analysis, namely UV−Visible spectrophotometry and FTIR of MB before treatment and degradation byproducts indicated deterioration of azo bond and demethylation. Moreover, the non-toxic nature of degradation byproducts was confirmed by phytotoxicity and cytotoxicity assays. Chlorella vulgaris retained its photosynthetic capability (˃ 85%) as estimated from Chlorophyll-a/b contents compared to ˃ 30% of MB-solution. However, the viability of Wi-38 and Vero cells was estimated to be 90.67% and 99.67%, respectively, upon exposure to MB-metabolites. Furthermore, an eminent employment of consortium either freely-suspended or immobilized in plain distilled water and optimized slurry in a bioaugmentation process was implemented to treat MB in artificially-contaminated municipal wastewater and industrial effluent. The results showed a corporative interaction between the consortium examined and co-existing microbiota; reflecting its compatibility and adaptability with different microbial niches in different effluents with various physicochemical contents.

TiO2@SiO2 nanoparticles for methylene blue removal and photocatalytic degradation under natural sunlight and low-power UV light

We have developed an efficient SiO2-TiO2 nanoparticle system with enhanced photocatalytic degradation under natural sunlight and low-power UV light. The SiO2-TiO2 system was synthesized by adding different mole ratios of SiO2 to TiO2, the ratios of 10:1, 5:1, and 2:1 have been used. SiO2-TiO2 nanoparticles with a 2:1 mole ratio showed enhanced photocatalytic degradation of methylene blue (MB) due to the presence of highly crystalline anatase TiO2 nanoparticles as well as good adsorption capacity due to the highly porous nature of samples. SiO2-TiO2 with a mole ratio of 5:1 showed the highest adsorption capacity of 88.6% after 30 min under dark conditions. Photocatalytic degradation of 90% and 85% was achieved for Si2Ti after 30 min in sunlight and UV light respectively. In addition, almost complete degradation of MB (98%) was obtained after 2 h in sunlight.

Evaluation of the Photocatalytic Activity and Anticorrosion Performance of Electrospun Fibers Doped with Metallic Oxides.

This paper reports the development and characterization of a multifunctional coating that combines anticorrosion and photocatalytic properties, deposited by means of the electrospinning technique. In the first step, a functional electrospun fiber mat composed of poly(acrylic acid) (PAA) and β-cyclodextrin (β-CD) was obtained, showing high water insolubility and great adhesion increased by means of a thermal crosslinking process (denoted as PAA + β-CD). In the second step, the fibers were doped with particles of titanium dioxide (denoted as PAA + β-CD/TiO2) and titanium dioxide plus iron oxide (denoted as PAA + β-CD/TiO2/Fe2O3). The morphology and fiber diameter of the electrospun mats were evaluated by using confocal microscopy, whereas the presence of the metal oxides in the electrospun fibers was corroborated by scanning electron microscopy (SEM) and X-ray fluorescence (XRF), respectively. In addition, electrochemical tests in saline solution revealed that the sample composed of PAA + β-CD/TiO2/Fe2O3 showed the highest corrosion protection efficiency of all the samples, which was directly associated to lower corrosion current density and higher corrosion potential. Furthermore, the paper reports a novel approach to in situ determination of methylene blue (MB) degradation onto the coating. The results revealed complete degradation of MB, which is perfectly appreciated by total discoloration of the film in the irradiated zone (from bluish to a white spot). The main conclusions of this research are the efficiency of the electrospun system PAA + β-CD/TiO2/Fe2O3 for developing photocatalytic activity and corrosion protection and the utility of the dry MB discoloration tests to evaluate photocatalytic activity.

The enhanced photocatalytic activity of ZnO nanorods/CuO nanourchins composite prepared by chemical bath precipitation

In this work, ZnO nanorods (NRs)/CuO nanourchins (NUs) were composed together to achieve the highest efficiency in methylene blue (MB) degradation. The nanocomposites were fabricated via a one-step, facile, and solution-based method named chemical bath precipitation. Crystal structures of hexagonal ZnO NRs and monoclinic CuO NUs phases were detected by X-ray diffraction (XRD) analysis, while field emission scanning electron microscopy (FESEM) confirmed the formation of ZnO NRs and CuO NUs with favorable interconnectivity. The chemical bonding stage of the Cu2+, Zn2+, and O2− were investigated with high-resolution X-ray photoelectron spectroscopy (HRXPS). Brunauer-Emmett-Teller (BET) method depicted a relatively wide pore size distribution for all the samples. Diffuse reflectance spectroscopy (DRS) demonstrated that band gap energy of ZnO NRs further narrowed by raising CuO concentration owing to the formation of the Cu(3d) energy state near the Zn(3d) valance band. Photoluminescence (PL) spectra revealed that the combination of ZnO NRs with CuO NUs significantly increased the lifetime of the photo-excited charge carriers. The ZnO/(10 mol%)CuO nanocomposite with the band gap energy of 2.9 eV and pore volume of 0.0180 cm3/g exhibited the highest efficiency and complete degradation of MB in less than 240 min. The photo-degradation kinetics of the as-prepared nanocatalyst followed a pseudo-first-order reaction model and exhibited about 12 times faster than ZnO. Finally, the photo-degradation mechanisms are proposed based on the role of reactive oxygen species and photo-generated charge carriers.

Cost Effective Solvothermal Method to Synthesize Zn-Doped TiO2 Nanomaterials for Photovoltaic and Photocatalytic Degradation Applications

Titanium dioxide (TiO2) is a commonly used wide bandgap semiconductor material for energy and environmental applications. Although it is a promising candidate for photovoltaic and photocatalytic applications, its overall performance is still limited due to low mobility of porous TiO2 and its limited spectral response. This limitation can be overcome by several ways, one of which is doping that could be used to improve the light harvesting properties of TiO2 by tuning its bandgap. TiO2 doped with elements, such as alkali-earth metals, transition metals, rare-earth elements, and nonmetals, were found to improve its performance in the photovoltaic and photocatalytic applications. Among the doped TiO2 nanomaterials, transition metal doped TiO2 nanomaterials perform efficiently by suppressing the relaxation and recombination of charge carriers and improving the absorption of light in the visible region. This work reports the possibility of enhancing the performance of TiO2 towards Dye Sensitised Solar Cells (DSSCs) and photocatalytic degradation of methylene blue (MB) by employing Zn doping on TiO2 nanomaterials. Zn doping was carried out by varying the mole percentage of Zn on TiO2 by a facile solvothermal method and the synthesized nanomaterials were characterised. The XRD (X-Ray Diffraction) studies confirmed the presence of anatase phase of TiO2 in the synthesized nanomaterials, unaffected by Zn doping. The UV-Visible spectrum of Zn-doped TiO2 showed a red shift which could be attributed to the reduced bandgap resulted by Zn doping. Significant enhancement in Power Conversion Efficiency (PCE) was observed with 1.0 mol% Zn-doped TiO2 based DSSC, which was 35% greater than that of the control device. In addition, it showed complete degradation of MB within 3 h of light illumination and rate constant of 1.5466×10−4s−1 resembling zeroth order reaction. These improvements are attributed to the reduced bandgap energy and the reduced charge recombination by Zn doping on TiO2.

Iron-impregnated spent coffee ground biochar for enhanced degradation of methylene blue during cold plasma application

This study investigates feasibility in the technical convergence of cold plasma and Fe-impregnated biochar to remove slowly-biodegradable methylene blue (MB) as a model contaminant. A problematic biowastes, spent coffee ground, was reused as a renewable source of biochar, and it impregnates Fe to enhance adsorption performance. Results verify that the cold plasma’s advanced oxidation coupled with the biochar increases overall MB removal efficiency and accelerates degradation kinetics. Experimental data regression verifies that the impregnated Fe significantly enhances the kinetic constants for total organic carbon (0.019–0.045min−1) and MB (0.050–0.065min−1). Also, it was confirmed that Fe-impregnation clearly shortens the periods required for almost complete MB degradation to within 1h. In addition, the higher Fe was impregnated, the stronger synergistic effects on MB degradation rates was observed. The analyses of nitrate, nitrite, and sulfate supports that the MB could be lower down to detection limit by the suggested combination. These results provide useful information about the synergistic combination of physicochemical processes as a viable option to effectively manage slowly-biodegradable pollutants.

Multi-applications of new trinuclear Zr-SMI complex

We report on the synthesis route and applications of new solid material Zirconium salicylate methylimidazole. Zirconium based complex was successfully synthesized by a cost-effective, simple stirring method on a hot water bath. The synthesized material arranged in layers with notable properties such as crystalline nature, highly homogeneous topology, and stable oxidation states at room temperature, and large surface area, and thermal stability. As-synthesized zirconium 3D H-bonded complex subjected to multiple applications since it has met desirable characteristics. Zr-SMI electrode has shown rare combination of pseudocapacitor-battery behavior. Supercapacity of 1165 mAhg−1 at 3 Ag−1 was achieved by the Zr-SMI electrode in basic electrolyte. Excellent electrochemical sensing response was found by the Zr-SMI electrode for an organic molecules such as Methylene blue (MB), and L-alanine analytes. In addition, Zr-SMI showed excellent catalytic property towards complete degradation of MB, Methyle orange (MO), and rhodium (RH) dyes. All these results implied the excellent electrochemical and catalytic behavior of Zr-SMI and proved as a promising material for multiple applications.

Efficient degradation and mineralization of methylene blue via continuous-flow electrohydraulic plasma discharge

A continuous-flow electrohydraulic plasma discharge (EHPD) process characteristic of establishing a stable discharge through the conducting channel of in the center orifice of a dielectric plate was developed and investigated to degrade methylene blue (MB) in water. The effect of three operating parameters, i.e., liquid flow rate (37−94 ml/min), air flow rate (1−4 L/min), and initial dye concentration (10−100 mg/L), on the MB degradation efficiency was evaluated. The results indicated that a complete degradation of MB was achieved within 10 min of treatment for all MB concentrations tested. The optimum liquid and air flow rates were 68 mL/min and 3 L/min, respectively, for the process to remove MB in a circular flow operation. The energy efficiency for different operating parameters was in the range of between 0.16 g/kWh and 0.81 g/kWh at 50% conversion. Reaction kinetics and the possible MB degradation pathway was analyzed and proposed. Hydroxyl radicals were found to be the dominant reactive species responsible for the MB degradation. Mineralization of MB was demonstrated by a 92.5% COD removal within10 min treatment for an initial MB concentration of 100 mg/L. The overall results indicated that the novel, continuous-flow EHPD reactor is a robust and highly effective process for degradation and mineralization of MB, a potential technology that can overcome the limitations of advanced oxidation processes for wastewater treatment.

Effect of the urea concentration on the luminescence and photocatalytic properties of Sr2CeO4 powders synthesized by a combustion method

This work presents the effect of urea on the morphological, structural, luminescent and photocatalytic properties of Sr2CeO4 (SCO) phosphors synthesized by a combustion method. Five SCO samples were synthesized using urea concentrations from 0 to 1 mol%. The X-ray diffraction patterns revealed that all the SCO samples presented an orthorhombic phase, while the morphological studies by scanning electron microscopy (SEM) indicated that the SCO powders are formed by coalesced microparticles with irregular shape, which have sizes of 0.5–1.5 μm and are decorated by smaller nanoparticles with sizes in the range of 30−250 nm. The Photoluminescence measurements revealed that all samples presented a broad blue emission band centered at 460 nm, which is produced by the Ce4+-O−2 charge transfer transition and the emission band at 517 nm was produced by the excitation of oxygen vacancies. Moreover, the photocatalytic activity of the SCO phosphors was evaluated by monitoring the degradation of methylene blue (MB) dye under solar light and UV irradiation. We found that only the sample synthesized with 1 mol% of urea produced a complete degradation of MB after 210 min and 540 min when it is irradiated with solar and UV light, respectively. In fact, the degradation of MB was 61 % faster under solar light. Furthermore, experiments for the detection of reactive oxygen species were achieved by using as scavengers benzoquinone, isopropyl alcohol and potassium iodide. From here, we determined that O2- is the dominant oxidizing agent for the degradation of MB. Thus, the results presented here demonstrate that SCO phosphors are efficient to remove dye contaminants from water, which of environmental interest.

Hydrothermal in situ preparation of phthalocyanine–TiO2 nanocomposites for photocatalytic activity under visible light irradiation

In this study, phthalocyanine (Pc)–TiO2 nanocomposites were prepared via in situ hydrothermal method. The metal-free, zinc(II), cobalt(II), nickel(II) and copper(II) Pc compounds were used for formation of nanocomposites. A total of 5 different Pc–TiO2 nanocomposites was successfully prepared by hydrothermal method. The prepared nanocomposites were also characterized by FT-IR, XRD, FEG-SEM, EDX, UV-DRS and BET techniques. All prepared nanocomposites were tested for their photocatalytic activity to be used as photocatalyst. For this purpose, photocatalytic activities of Pc–TiO2 nanocomposites were evaluated for the degradation efficiency of methylene blue (MB) under visible light irradiation by monitoring the UV–Vis absorption spectra. Based on the conducted studies, it was observed that Pc–TiO2 photocatalysts have significant photocatalytic activities on degradation of MB under visible light irradiation, resulting in complete degradation of MB in 100–130 min for full degradation (100%). Furthermore, the reusability studies revealed that photocatalysts show 76% activity even after 5 uses. In this study, we prepared and characterized TiO2 nanocomposites using peripherally tetra-substituted metal-free, Zn(II), Co(II), Ni(II) and Cu(II) phthalocyanine complexes. The phthalocyanine–TiO2 nanocomposites showed significant photocatalytic activities for cleaning a common organic pollutant under the visible light irradiation.

Elbaite catalyze peroxymonosulfate for advanced oxidation of organic pollutants: Hydroxyl groups induced generation of reactive oxygen species

In this work, the abundant, low−cost, innocuous, and chemically stable elbaite (a type of tourmaline) was employed to catalyze peroxymonosulfate (PMS) for wastewater purification by using methylene blue (MB) as one of the target pollutants. The results revealed that PMS could be catalyzed by elbaite within broad pH range (i.e., 2.9–10.7) and with low activation energy (i.e., 18.6 kJ/mol). Complete MB degradation was obtained within 15 min under the optimized conditions: [elbaite]0 = 1.00 g/L, [PMS]0 = 0.50 g/L, initial solution pH = 2.9. MB degradation (%) sustained 99.9 % after five successive catalytic reactions, indicating good durability and long−term stability. In addition, the complete degradation of doxycycline hydrochloride (DOX) and bisphenol A (BPA) further confirmed the degradation activity of the PMS/elbaite system. PMS interacted with elbaite via replacing the surface−bonded and structural OH groups of elbaite with its OH groups to bond with YLiYAlYR and YLiZAlZR cations (R = Al, Li, Fe, Mg, Mn, Cr, V), which offered channels for electron transfer from negatively charged elbaite to PMS, leading to the activation of PMS. Thus, elbaite is found to be promising for catalyzing PMS to treat organic wastewater.