Factors influencing the photocatalytic degradation of Rhodamine B by TiO2-coated non-woven paper

Recent trends and advancement in metal oxide nanoparticles for the degradation of dyes: synthesis, mechanism, types and its application

Synthetic dyes play a crucial role in our daily lives, especially in clothing, leather accessories, and furniture manufacturing. Unfortunately, these potentially carcinogenic substances are significantly impacting our water systems due to their widespread use. Dyes from various sources pose a serious environmental threat owing to their persistence and toxicity. Regulations underscore the urgency in addressing this problem. In response to this challenge, metal oxide nanoparticles such as titanium dioxide (TiO2), zinc oxide (ZnO), and iron oxide (Fe3O4) have emerged as intriguing options for dye degradation due to their unique characteristics and production methods. This paper aims to explore the types of nanoparticles suitable for dye degradation, various synthesis methods, and the properties of nanoparticles. The study elaborates on the photocatalytic and adsorption-desorption activities of metal oxide nanoparticles, elucidating their role in dye degradation and their application potential. Factors influencing degradation, including nanoparticle properties and environmental conditions, are discussed. Furthermore, the paper provides relevant case studies, practical applications in water treatment, and effluent treatment specifically in the textile sector. Challenges such as agglomeration, toxicity concerns, and cost-effectiveness are acknowledged. Future advancements in nanomaterial synthesis, their integration with other materials, and their impact on environmental regulations are potential areas for development. In conclusion, metal oxide nanoparticles possess immense potential in reducing dye pollution, and further research and development are essential to define their role in long-term environmental management.

Janus Micromotors for Photophoretic Motion and Photon Upconversion Applications Using a Single Near-Infrared Wavelength

External stimuli can trigger changes in temperature, concentration, and momentum between micromotors and the medium, causing their propulsion and enabling them to perform different tasks with improved kinetic efficiencies. Light-activated micromotors are attractive systems that achieve improved motion and have the potential for high spatiotemporal control. Photophoretic swarming motion represents an attractive means to induce micromotor movement through the generation of temperature gradients in the medium, enabling the micromotors to move from cold to hot regions. The micromotors studied herein are assembled with Fe3O4 nanoparticles, and NaGdF4:Yb3+,Er3+/NaGdF4:Yb3+ and LiYF4:Yb3+,Tm3+ upconverting nanoparticles. The Fe3O4 nanoparticles were localized to one hemisphere to produce a Janus architecture that facilitates improved upconversion luminescence with the upconverting nanoparticles distributed throughout. Under 976 nm excitation, Fe3O4 nanoparticles generate the temperature gradient, while the upconverting nanoparticles produce visible light that is used for micromotor motion tracking and triggering of reactive oxygen species generation. As such, the motion and application of the micromotors are achieved using a single excitation wavelength. To demonstrate the practicality of this system, curcumin was adsorbed to the micromotor surface and degradation of Rhodamine B was achieved with kinetic rates that were over twice as fast as the static micromotors. The upconversion luminescence was also used to track the motion of the micromotors from a single image frame, providing a convenient means to understand the trajectory of these systems. Together, this system provides a versatile approach to achieving light-driven motion while taking advantage of the potential applications of upconversion luminescence such as tracking and detection, sensing, nanothermometry, particle velocimetry, photodynamic therapy, and pollutant degradation.

Sustainable approaches for removing Rhodamine B dye using agricultural waste adsorbents: A review

Rhodamine B (RhB) is among the toxic dyes due to the carcinogenic, neurotoxic effects and ability to cause several diseases for humans. The adsorption with agricultural waste adsorbent recorded high performance for the RhB removal. The current review aimed to explore the efficiency of different adsorbents which have been used in the few last years for removing RhB dye from wastewater. The data of adsorption of RhB using agricultural wastes were collected from the Scopus database in the period between 2015 and 2021. The use of agricultural wastes and adsorbents as a replacement for the activated has received high attention among researchers. The RhB removal methods by microbial enzymes and biomass occurred between 76 and 90.1%. In comparison, the adsorption with agricultural wastes such as activated carbon white sugar reached 98% within 12 min. The adsorption process has a wide range of pH (3-10) due to the zwitterionic forms of RhB. Gmelina aborea leaf activated carbon is among the agriculture wastes absorbents that exhibited 1000 mg g^-1 of the adsorption capacity. It appeared that the agricultural wastes adsorbents have a high potential for removing RhB from the wastewater.

Photocatalytic degradation of Rhodamine-B by visible light assisted peroxymonosulfate activation using Z-scheme MIL-100(Fe)/Bi2S3 composite: a combined experimental and theoretical approach

The photocatalytic efficiency of binary MIL-100(Fe)/Bi2S3 (MIL-BS) composite was utilized towards visible light assisted peroxymonosulfate (PMS) activation and degradation of Rhodamine-B (RhB) dye. The binary catalyst, with 10wt% Bi2S3 (MIL-BS(10)),...

Ti2O3/TiO2-Assisted Solar Photocatalytic Degradation of 4-tert-Butylphenol in Water

Colored Ti2O3 and Ti2O3/TiO2 (mTiO) catalysts were prepared by the thermal treatment method. The effects of treatment temperature on the structure, surface area, morphology and optical properties of the as-prepared samples were investigated by XRD, BET, SEM, TEM, Raman and UV–VIS spectroscopies. Phase transformation from Ti2O3 to TiO2 rutile and TiO2 anatase to TiO2 rutile increased with increasing treatment temperatures. The photocatalytic activities of thermally treated Ti2O3 and mTiO were evaluated in the photodegradation of 4-tert-butylphenol (4-t-BP) under solar light irradiation. mTiO heated at 650 °C exhibited the highest photocatalytic activity for the degradation and mineralization of 4-t-BP, being approximately 89.8% and 52.4%, respectively, after 150 min of irradiation. The effects of various water constituents, including anions (CO32−, NO3, Cl and HCO3−) and humic acid (HA), on the photocatalytic activity of mTiO-650 were evaluated. The results showed that the presence of carbonate and nitrate ions inhibited 4-t-BP photodegradation, while chloride and bicarbonate ions enhanced the photodegradation of 4-t-BP. As for HA, its effect on the degradation of 4-t-BP was dependent on the concentration. A low concentration of HA (1 mg/L) promoted the degradation of 4-t-BP from 89.8% to 92.4% by mTiO-650, but higher concentrations of HA (5 mg/L and 10 mg/L) had a negative effect.

Metal Oxide-Based Photocatalytic Paper: A Green Alternative for Environmental Remediation

The interest in advanced photocatalytic technologies with metal oxide-based nanomaterials has been growing exponentially over the years due to their green and sustainable characteristics. Photocatalysis has been employed in several applications ranging from the degradation of pollutants to water splitting, CO2 and N2 reductions, and microorganism inactivation. However, to maintain its eco-friendly aspect, new solutions must be identified to ensure sustainability. One alternative is creating an enhanced photocatalytic paper by introducing cellulose-based materials to the process. Paper can participate as a substrate for the metal oxides, but it can also form composites or membranes, and it adds a valuable contribution as it is environmentally friendly, low-cost, flexible, recyclable, lightweight, and earth abundant. In term of photocatalysts, the use of metal oxides is widely spread, mostly since these materials display enhanced photocatalytic activities, allied to their chemical stability, non-toxicity, and earth abundance, despite being inexpensive and compatible with low-cost wet-chemical synthesis routes. This manuscript extensively reviews the recent developments of using photocatalytic papers with nanostructured metal oxides for environmental remediation. It focuses on titanium dioxide (TiO2) and zinc oxide (ZnO) in the form of nanostructures or thin films. It discusses the main characteristics of metal oxides and correlates them to their photocatalytic activity. The role of cellulose-based materials on the systems’ photocatalytic performance is extensively discussed, and the future perspective for photocatalytic papers is highlighted.

Transforming micelles into mixed micelles: a promising approach to tune the catalytic performance of imidazolium-based surface active ionic liquids toward degradation of rhodamine B

Herein, we demonstrate that the catalytic performance of imidazolium-based surface-active ionic liquid (SAIL) micelles can be significantly enhanced through the addition of an appropriate type and amount of intelligently conceived amphiphile to form mixed micelles. Specifically, we show that the catalytic performance of 1-dodecyl-3-methyl imidazolium chloride (DDMIMCl) micelles toward the reductive degradation of rhodamine B (RhB), a carcinogenic dye extensively used in multiple industrial applications, can be appreciably boosted through addition of Brij56, a nonionic surfactant. Detailed kinetic investigations on the catalytic performance of pre- and post-micellar concentrations of DDMIMCl and its mixed micelles with Brij56 over various mole fractions, toward the reductive degradation of RhB, are presented. The data analyzed in light of Berezin's kinetic model suggest that the addition of Brij56 to DDMIMCl micelles significantly enhances their catalytic performance. The catalytic activity exhibited by the DDMIMCl-Brij56 (X_Brij56 = 0.2) mixed micellar system is better than that reported for many state-of-the-art nanoparticle/homogenous catalysts. The results explained in light of Berezin's kinetic model are well supported by physico-chemical studies like conductometry, fluorimetry and dynamic light scattering. The presented results anticipate stimulation of extensive research activity for exploiting the mixed micellization approach as a novel avenue for modulating the catalytic performance of SAILs.

Anti-algal activity of Fe2O3-TiO2 photocatalyst on Chlorella vulgaris species under visible light irradiation

Many industries located in coastal areas use a large amount of seawater. Algal biofouling can be a major problem that hinders the efficiency of these industrial facilities. In most cases, seawater requires algal removal pre-treatment to avoid or mitigate biofilm formation. To remediate green microalgae, Fe₂O₃-TiO₂ nanoparticles with 2.5% w/w Fe₂O₃ were applied as a visible light driven photocatalyst. The anti-algal activity of the photocatalytic pre-treatment using green microalgae, Chlorella vulgaris was tested. The experiments were carried out in freshwater, artificial seawater, and real seawater. Effect of photocatalyst dosage, visible light intensity, and water salinity on the removal of microalgae was investigated. The highest inactivation efficiency of Chlorella vulgaris was achieved under 55 W/m² visible light irradiation when 0.25 g/L of Fe₂O₃-TiO₂ photocatalyst was used. The photocatalytic removal kinetics of Chlorella vulgaris followed the pseudo first order Langmuir-Hinshelwood model. The results revealed that the efficiency of photocatalytic removal of algae decreased with increasing of seawater salinity. The anti-algal activity of Fe₂O₃-TiO₂ nanoparticles was attributed to the generation of reactive oxygen species (ROS) through the photocatalytic process. H⁺ radical was shown to be the most important ROS that nanoparticles produced in the aqueous media. Using Fe₂O₃-TiO₂ nanoparticles in photocatalytic pre-treatment could be an efficient environmental-friendly method for micro-algal remediation in seawater under visible light.

Influence of Mg, Cu, and Ni Dopants on Amorphous TiO2 Thin Films Photocatalytic Activity

The present study investigates Mg (0 ÷ 17.5 wt %), Cu (0 ÷ 21 wt %) and Ni (0 ÷ 20.2 wt %) dopants (M-doped) influence on photocatalytic activity of amorphous TiO₂ thin films. Magnetron sputtering was used for the deposition of M-doped TiO₂ thin films. According to SEM/EDS surface analysis, the magnetron sputtering technique allows making M-doped TiO₂ thin films with high uniformity and high dopant dispersion. Photocatalysis efficiency analysis was set in oxalic acid under UV irradiation. In accordance with the TOC (total organic carbon) measurements followed by the apparent rate constant (k_app) results, the dopants’ concentration peak value was dopant-dependent; for Mg/TiO₂, it is 0.9% (k_app—0.01866 cm⁻¹), for Cu/TiO₂, it is 0.6% (k_app—0.02221 cm⁻¹), and for Ni/TiO₂, it is 0.5% (k_app—0.01317 cm⁻¹). The obtained results clearly state that a concentration of dopants in TiO₂ between 0.1% and 0.9% results in optimal photocatalytic activity.

Photocatalytic degradation and kinetic modeling of azo dye using bimetallic photocatalysts: effect of synthesis and operational parameters

Industrial wastewaters are the major source polluting the surface and ground water resources. Pollutants released along with the untreated textile industry wastewaters are responsible for the great damage to the natural resources like water. Considering the hazardous effects of the azo dyes (textile coloring agents) and their byproducts, there is a need to develop cost-effective and efficient treatment method for the textile wastewaters as such dyes have been reported as toxic, mutagenic, and carcinogenic and can cause direct demolition of aquatic communities. One of the possible and effective treatment methods is the use of TiO₂ photocatalysis due to its chemical stability, low cost, and non-toxic nature. The present study explored the photocatalytic potential of anatase-type of bimetallic Cu-Ni/TiO₂ photocatalysts under visible light irradiation for possible photocatalytic degradation and mineralization of Methyl Orange (MO), as model azo dye. The focus was to correlate the synthesis (different calcination temperatures, phase composition of TiO₂ either anatase or rutile, and metal ion loading in terms of concentration and composition (Cu:Ni)) and operational parameters (photocatalyst loading, pollutant concentration, and irradiation time) that were believed responsible for the enhanced photocatalytic performance. Blank experiments were carried out to check the effect of metal loading in comparison to bare TiO₂ and effect of absence or presence of light and photocatalysts on MO photodegradation. Results obtained using bimetallic photocatalysts are promising as compared to bare TiO₂ as 100% MO removal and ~ 90% %COD removal were obtained in 90 min of irradiation, obeying a pseudo-first-order kinetics with photocatalytic reaction via the Langmuir-Hinshelwood mechanism with a good linear fit. Photocatalysts synthesized using anatase TiO₂ were reported with improved performance compared to rutile phase. It is evident that synthesis parameters influence photocatalyst performance directly. The higher rate constant (> 1) that proves the excellent adsorption capacity of the tested photocatalysts for tested pollutants on the surface may have a great prospective for photocatalytic water purification at neutral pH.

Sunlight assisted degradation of a pollutant dye in water by a WO3@g-C3N4 nanocomposite catalyst

A series of WO₃@g-C₃N₄ nanocomposites were prepared by following a facile, cost-effective chemical rote and characterized by different techniques. They are promising photocatalyst with high potential for solar light harvesting and environmental remediation.

Production of iron oxide and nickel oxide nanostructural particles, investigation of the supercapacitor and photocatalytic properties

In this study, iron oxide, nickel oxide, and nickel-iron oxide nanostructured particles were produced by the hydrothermal method. X-ray diffraction (XRD) and SEM measurements were performed to investigate the physical properties of these nanostructured particles. According to the XRD results, the crystal properties of these particles were determined. From the SEM images, these particles understood to be nano-structured. The electrodes were examined for electrochemical properties by using these nanostructured particles. Electrochemical measurements of the produced electrodes were performed, and capacitance values and impedance spectra of the electrodes were determined. The specific capacitance values of the iron oxide, nickel-iron oxide, and nickel oxide nanostructured particles, respectively are 30 F/g, 55 F/g, and 67 F/g. Also, the photocatalytic activities of nanostructured particles were investigated. This examination methylene blue (MB) was used and made under a xenon lamp. In light of our findings, it was observed that high photocatalytic degradation rate. Nickel-iron oxide nanostructured particles, the degradation of MB were found to be about 87%.

Piezoelectric Material-Polymer Composite Porous Foam for Efficient Dye Degradation via the Piezo-Catalytic Effect

Piezoelectric nanomaterials have been utilized to realize effective charge separation for degrading organic pollutants in water under the action of mechanical vibrations. However, in particulate form, the nanostructured piezoelectric catalysts can flow into the aqueous pollutant and limit its recyclability and reuse. Here, we report a new method of using a barium titanate (BaTiO₃, BTO)-polydimethylsiloxane composite porous foam catalyst to address the challenge of secondary pollution and reusable limits. Piezo-catalytic dye degradation activity of the porous foam can degrade a Rhodamine B (RhB) dye solution by ∼94%, and the composite material exhibits excellent stability after repeated decomposition of 12 cycles. It is suggested that under ultrasonic vibrations, the piezoelectric BTO materials create separated electron-hole pairs that react with hydroxyl ions and oxygen molecules to generate superoxide (^•O₂^-) and hydroxyl (^•OH) radicals for organic dye degradation. The degradation efficiency of RhB is associated with the piezoelectric constant, the specific surface area, and the shape of the material.

Recent Advances and Applications of Semiconductor Photocatalytic Technology

Along with the development of industry and the improvement of people’s living standards, peoples’ demand on resources has greatly increased, causing energy crises and environmental pollution. In recent years, photocatalytic technology has shown great potential as a low-cost, environmentally-friendly, and sustainable technology, and it has become a hot research topic. However, current photocatalytic technology cannot meet industrial requirements. The biggest challenge in the industrialization of photocatalyst technology is the development of an ideal photocatalyst, which should possess four features, including a high photocatalytic efficiency, a large specific surface area, a full utilization of sunlight, and recyclability. In this review, starting from the photocatalytic reaction mechanism and the preparation of the photocatalyst, we review the classification of current photocatalysts and the methods for improving photocatalytic performance; we also further discuss the potential industrial usage of photocatalytic technology. This review also aims to provide basic and comprehensive information on the industrialization of photocatalysis technology.

Strong vibration-catalysis of ZnO nanorods for dye wastewater decolorization via piezo-electro-chemical coupling

A novel vibration-catalytic performance based on piezo-electro-chemical coupling of zinc oxide (ZnO) nanorods for wastewater decolorization was characterized through the product of piezoelectric performance and electrochemical process. The vibration-catalytic decolorization ratio for acid orange 7 (AO7) solution (5 μM) was up to ∼ 80%. The oxidizing hydroxyl radical (OH) of the intermediates of the vibration-catalytic reactions is observed, indicating the production of piezoelectrically-induced electric charges. The dependence of ZnO addition mass, initial dye concentration and the recycling utilization times of ZnO on dye decolorization ratio were systematically studied. The vibration-catalysis mediated by ZnO, with the advantages of high efficiency and recycling utilization, is potential for dye wastewater decolorization treatment.

Construction of highly efficient and stable ternary AgBr/Ag/PbBiO2Br Z-scheme photocatalyst under visible light irradiation: Performance and mechanism insight

In this work, the novel ternary AgBr/Ag/PbBiO₂Br Z-scheme photocatalysts were synthesized via a CTAB-assisted calcination process. The AgBr/Ag/PbBiO₂Br composites were employed for the degradation of rhodamine B (RhB) and antibiotic bisphenol A (BPA) under visible light irradiation. Results showed that the obtained AgBr/Ag-3/PbBiO₂Br displayed optimal photocatalytic performance, which could remove almost all RhB within 25 min and effectively decompose 82.3% of BPA in 120 min. Three-dimensional excitation-emission matrix fluorescence spectra (3D EEMs) were utilized for the purposes of fully grasping the behaviors of RhB molecules during the reaction process. Meanwhile, the effects of initial RhB concentration and co-existent electrolytes were investigated from the viewpoint of practical application. In addition, there was no obvious loss in degradation efficiency even after four cycles. The enhanced photocatalytic performances of AgBr/Ag/PbBiO₂Br could be credited to the accelerated interfacial charge transfer process and the improved separation of the photogenerated electron-hole pairs. The existence of a small amount of metallic Ag played a significant role in preventing AgBr from being further photocorroded, resulting in the formation of a stable Z-scheme photocatalyst system. This study demonstrated that using metallic Ag as an electron mediator to construct Z-scheme photocatalytic system provided a feasible strategy in promoting the stability of Ag-based semiconductors.

Synthesis of Pt@TiO2@CNTs Hierarchical Structure Catalyst by Atomic Layer Deposition and Their Photocatalytic and Photoelectrochemical Activity

Pt@TiO₂@CNTs hierarchical structures were prepared by first functionalizing carbon nanotubes (CNTs) with nitric acid at 140 °C. Coating of TiO₂ particles on the CNTs at 300 °C was then conducted by atomic layer deposition (ALD). After the TiO₂@CNTs structure was fabricated, Pt particles were deposited on the TiO₂ surface as co-catalyst by plasma-enhanced ALD. The saturated deposition rates of TiO₂ on a-CNTs were 1.5 Å/cycle and 0.4 Å/cycle for substrate-enhanced process and linear process, respectively. The saturated deposition rate of Pt on TiO₂ was 0.39 Å/cycle. The photocatalytic activities of Pt@TiO₂@CNTs hierarchical structures were higher than those without Pt co-catalyst. The particle size of Pt on TiO₂@CNTs was a key factor to determine the efficiency of methylene blue (MB) degradation. The Pt@TiO₂@CNTs of 2.41 ± 0.27 nm exhibited the best efficiency of MB degradation.

Enhanced photocatalytic activities of single-crystalline ZnGa2O4 nanoprisms by the coexposed {111} and {110} facets

Facet-control has been a fascinating method for preparation of highly active photocatalysts. Herein, we report the hydrothermal preparation of single-crystalline ZnGa₂O₄ nanoprisms with the {111} and {110} facets coexposed. Studies of their photocatalytic performance have revealed that the as-formed nanoprisms exhibit significantly enhanced photocatalytic activities compared with ZnGa₂O₄ nanocubes with only the {100} facets exposed and nanosheets with the {110} facets exposed for H₂ evolution and contaminant degradation. Theoretical calculations combined with valence band XPS results indicate the formation of a surface heterojunction by the coexposed {111} and {110} facets, which promotes the photogenerated electron and hole migration to the {110} and {111} facets, respectively, and enhances the photocatalytic performance.

Application of Fenton oxidation to reduce the toxicity of mixed parabens

The aims of the present work were to assess the application of a chemical process to degrade a mixture of parabens and determine the influence of a natural river water matrix on toxicity. Model effluents containing either a single compound, namely methylparaben, ethylparaben, propylparaben, butylparaben, benzylparaben or p-hydroxybenzoic acid, or to mimic realistic conditions a mixture of the six compounds was used. Fenton process was applied to reduce the organic charge and toxic properties of the model effluents. The efficiency of the decontamination has been investigated using a chemical as well as a toxicological approach. The potential reduction of the effluents' toxicity after Fenton treatment was evaluated by assessing (i) Vibrio fischeri luminescence inhibition, (ii) lethal effects amongst freshwater Asian clams (Corbicula fluminea), and (iii) the impact on mammalian neuronal activity using brain slices. From the environmental point of view such a broad toxicity analysis has been performed for the first time. The results indicate that Fenton reaction is an effective method for the reduction of chemical oxygen demand of a mixture of parabens and their toxicity to V. fischeri and C. fluminea. However, no important differences were found between raw and treated samples in regard to mammalian neuronal activity.

Strong pyro-catalysis of pyroelectric BiFeO3 nanoparticles under a room-temperature cold-hot alternation

A strong pyro-catalytic dye degradation with an ultrahigh degradation efficiency (>99%) in hydrothermally synthesized pyroelectric BiFeO3 nanoparticles was achieved under a room-temperature cold-hot alternating excitation (between 27 °C to 38 °C). The pyro-catalysis originated from a combination of the pyroelectric effect and the electrochemical oxidation-reduction reaction. The intermediate products (hydroxyl radicals and superoxide radicals) of pyro-electro-catalysis were observed. Pyro-catalysis provides a highly efficient and reusable dye wastewater decomposition technology through utilizing environmental day-night temperature variation.

Synthesis of TiO2-loaded silicate-1 monoliths and their application for degradation rhodamine B

TiO₂-loaded silicate-1 monoliths, with TiO₂ (Degussa P25) nanoparticles loaded in silicate-1 crystal, were directly synthesized by combining sol–gel method and hydrothermal method.

Design of a Metal Oxide-Organic Framework (MoOF) Foam Microreactor: Solar-Induced Direct Pollutant Degradation and Hydrogen Generation

A macroporous carbon network combined with mesoporous catalyst immobilization by a template method gives a metal-oxide-organic framework (MoOF) foam microreactor that readily soaks up pollutants and localizes solar energy in itself, leading to effective degradation of water pollutants (e.g., methyl orange (MO) and also hydrogen generation. The cleaned-up water can be removed from the microreactor simply by compression, and the microreactor used repeatedly.

Studies on adsorption, reaction mechanisms and kinetics for photocatalytic degradation of CHD, a pharmaceutical waste

The photocatalytic degradation of chlorhexidine digluconate (CHD), a disinfectant and topical antiseptic and adsorption of CHD catalyst surface in dark condition has been studied. Moreover, the value of kinetic parameters has been measured and the effect of adsorption on photocatalysis has been investigated here. Substantial removal was observed during the photocatalysis process, whereas 40% removal was possible through the adsorption route on TiO2 surface. The parametric variation has shown that alkaline pH, ambient temperature, low initial substrate concentration, high TiO2 loading were favourable, though at a certain concentration of TiO2 loading, photocatalytic degradation efficiency was found to be maximum. The adsorption study has shown good confirmation with Langmuir isotherm and during the reaction at initial stage, it followed pseudo-first-order reaction, after that Langmuir Hinshelwood model was found to be appropriate in describing the system. The present study also confirmed that there is a significant effect of adsorption on photocatalytic degradation. The possible mechanism for adsorption and photocatalysis has been shown here and process controlling step has been identified. The influences of pH and temperature have been explained with the help of surface charge distribution of reacting particles and thermodynamic point of view respectively.

Adsorption-assisted photocatalytic activity of nitrogen and sulfur codoped TiO2 under visible light irradiation

Herein, we synthesized the N- and S-codoped TiO₂ (NSTs) with an anatase phase using a simple solvothermal treatment and investigated their visible light photocatalytic activity associated with the thermal behavior of dopants in NSTs.

Metal oxide nanostructures incorporated/immobilized paper matrices and their applications: a review

A comprehensive review on the metal oxide nanostructures incorporated/immobilized paper matrices byex situandin situmethods for various applications.

Characterization and photocatalytic performance evaluation of various metal ion-doped microstructured TiO2 under UV and visible light

Commercially available microcrystalline TiO2 was doped with silver, ferrous and ferric ion (1.0 mol %) using silver nitrate, ferrous sulfate and ferric nitrate solutions following the liquid impregnation technology. The catalysts prepared were characterised by FESEM, XRD, FTIR, DRS, particle size and micropore analysis. The photocatalytic activity of the prepared catalysts was tested on the degradation of two model dyes, methylene blue (3,7-bis (Dimethylamino)-phenothiazin-5-ium chloride, a cationic thiazine dye) and methyl blue (disodium;4-[4-[[4-(4-sulfonatoanilino)phenyl]-[4-(4-sulfonatophenyl)azaniumylidenecyclohexa-2,5-dien-1-ylidene]methyl]anilino]benzene sulfonate, an anionic triphenyl methane dye) under irradiation by UV and visible light in a batch reactor. The efficiency of the photocatalysts under UV and visible light was compared to ascertain the light range for effective utilization. The catalysts were found to have the anatase crystalline structure and their particle size is in a range of 140-250 nm. In the case of Fe(2+) doped TiO2 and Fe(3+) doped TiO2, there was a greater shift in the optical absorption towards the visible range. Under UV light, Ag(+) doped TiO2 was the most efficient catalyst and the corresponding decolorization was more than 99% for both the dyes. Under visible light, Fe(3+) doped TiO2 was the most efficient photocatalyst with more than 96% and 90% decolorization for methylene blue and methyl blue, respectively. The kinetics of the reaction under both UV and visible light was investigated using the Langmuir-Hinshelwood pseudo-first-order kinetic model. Kinetic measurements confirmed that, Ag(+) doped TiO2 was most efficient in the UV range, while Fe(3+) doped TiO2 was most efficient in the visible range.

An inhibitory effect of self-assembled soft systems on Fenton driven degradation of xanthene dye Rhodamine B

Rhodamine B (RhB) is known to be a common organic pollutant despite having various technical applications. Treatment of effluents containing such compounds is important so as to minimize their effect on environment. Advanced Oxidation Processes (Fenton and Fenton like reactions) are such methods that can oxidize the contaminants powerfully and non-selectively. This work investigates the oxidation kinetics of dye RhB by hydroxyl radical (OH) generated via Fenton reaction in presence of surfactant assemblies of varying architectures using spectrophotometric, spectrofluorometic and tensiometric methods. The presence of surfactants viz. cationics, non-ionics and some binary mixtures in the pre-micellar and post micellar concentration ranges were found to inhibit the degradation of RhB to a varying degree. However, the reaction was totally inhibited in anionic surfactant. The experimental data was fitted to a pseudo first order kinetic model and the kinetic parameters obtained thereof were explained on the basis of the nature and type of interaction between the cationic form of RhB and the surfactants of varying architectures. The work has a critical significance in view of the fact that degradation studied in presence of surfactant assemblies is more representative than studied in aqueous solution because such conditions compare well with the conditions prevailing in the environment.