Mineralization Of Dye Research Articles

Boosting the antimicrobial and Azo dye mineralization activities of ZnO ceramics by enhancing the light-harvesting and charge transport properties

Herein, we report the wet-chemical synthesis of a ferromagnetic nickel-doped ZnO (Zn1-xNixO) nanocatalyst as a novel and visible-light-driven photocatalyst. Through X-ray diffraction, UV/Vis absorption, electronic studies, and current-voltage experiments, the effect of the ferromagnetic nickel dopant on the structural, optical, morphological, and electrical properties of the synthesized Zn1-xNixO nanocatalyst was studied. The Ni-doping introduced the structural variation in the Zn1-xNixO nanocatalyst, exhibiting a visible light-triggered optical band gap of 2.96 eV and an excellent current conductivity of 6.3 × 10−4 Sm−1. Moreover, the synthesis of the Zn1-xNixO catalyst at the nanoscale enhanced its surface energy, showing a robust affinity to stick with the dye and pathogenic microbes. The synergistic effects of all the mentioned features enable our Zn1-xNixO nanocatalyst to efficiently generate and transport reactive oxygen species (ROS) under visible light illumination. Regarding antibacterial action, the as-synthesized Zn1-xNixO nanocatalyst showed 1.7% higher activity against E. coli than that of the drug Ciprofloxacin. In addition, doped nanocatalysts mineralize almost 97% of the Allura red dye in just 80 min with a constant rate value of 0.036 min−1. The impedance study and post-application XRD proposed that our Zn1-xNixO nanocatalyst has good conductivity and structural stability. Applications studies show the unusual photocatalytic activity of as-synthesized Zn1-xNixO nanocatalysts, which makes it a suitable candidate for industrial discharge treatment applications at the expense of solar light.

Detoxification of harmful pollutants using highly efficient visible light active Ru/TiO2/PVDF photocatalytic membranes

In this study, the pristine PVDF and x% Ru/TiO2/PVDF (x = 0. 5, 1 & 1. 5 wt.%) photocatalytic composite membranes were cast by the phase inversion method. The prepared photocatalysts and photocatalytic membranes were characterized by various analytical techniques. All the prepared photocatalysts and photocatalytic membranes were evaluated for their photocatalytic activities towards the degradation of two significant hazardous textile dyes, namely methylene blue and crystal violet under visible light illumination. The% decolorization values of MB and CV dyes over 1% Ru/TiO2 photocatalyst & 1% Ru/TiO2/PVDF photocatalytic composite membrane were found to be 99% & 97% and 84% & 83% respectively under visible light irradiation. The photocatalytic decolorization followed the pseudo-first-order reaction, according to the kinetics investigations. The mineralization of MB and CV dyes was determined by TOC analysis and found to be 64% & 61% respectively. The recyclability of 1% Ru/TiO2/PVDF photocatalytic composite membrane test revealed high stability.

Facile synthesis of a ZnO/Fe2O3 heterostructure and its graphene-reinforced composite for boosting the photo-mineralization of crystal violet and phenol

Abstract Herein, a nanostructured ZnO/Fe2O3 heterostructure and its graphene (Gr)-reinforced composite (ZnO/Fe2O3@Gr) have been synthesized via co-precipitation and post-ultrasonication approaches. The formation of heterojunction at the ZnO–Fe2O3 interface reduces the bandgap and keeps the electron-hole pairs apart. The graphene plays multiple roles to boost the dye removal effectively of the ZnO/Fe2O3@Gr composite. The charge transfer aptitude, isolation of charge carriers, and resistance at the ZnO/Fe2O3-Graphene interface were also examined by Mott–Schottky, chronoamperometric, and impedance experiments. The performance of an as-synthesized ZnO/Fe2O3@Gr catalyst was explored for the mineralization of a cationic dye (crystal violet, CV) and phenol in visible-light (λ above 400 nm) for 2 h. The ZnO/Fe2O3@Gr catalyst has mineralized 92.8 % CV dye and 50.86 % phenol after 2 h of visible-light irradiation. Moreover, the mineralization constant (k) comes to be 0.019 min−1, which is 4.2, 2.3, and 1.7 times higher than ZnO, Fe2O3, and ZnO/Fe2O3 catalysts, respectively. Increasing the dosage of the ZnO/Fe2O3@Gr catalyst from 10 mg to 30 mg increased the rate constant from 0.006 min−1 to 0.019 min−1, thereby increasing the efficiency of CV dye mineralization from 58.5 % to 92.8 %. The tuned photocatalytic activity of the ZnO/Fe2O3@Gr is due to the formation of the ZnO–Fe2O3 heterostructure and, preferentially, its conductive graphene. In fact, graphene serves the roles of an efficient electron collector, a transporter, and an effective UV/Vis light absorber, enabling the creation of active species that further boost the photocatalytic performance. According to the results of this study, the easiest and cheapest way to deal with toxic dyes in industrial waste is to make photocatalysts from semiconductive and carbonaceous materials that have integrated properties.

Synthesis of doped and porous CuO with boosted light-harvesting features for the photocatalytic mineralization of azo dyes

Porous Ni-doped copper oxide (NCO) photocatalyst has been produced using chemical activation and metal doping techniques. Structural, optical, morphological, and electrical analyses were performed on copper oxide (CO) and porous NCO photocatalysts. The monoclinic-phased, UV/Vis light-triggered, electrically conductive, and porous-surfaced NCO photocatalyst was successfully synthesized, according to a detailed physicochemical investigation. The photo-decomposition abilities of synthetic porous NCO and counterpart CO photocatalysts were investigated and compared using Allura red (AR). According to the photocatalytic study, the porous NCO photocatalyst outperformed its counterpart (CuO) and eliminated 91.4% (adsorption: 18%; decomposition: 79%) of the AR dye in 48 min. Over the porous NCO photocatalyst, the AR dye disintegrated at a rate of 0.024 min−1, which is more than 1.84 times quicker than the rate of disintegration over the CO photocatalyst. The porous NCO photocatalyst, as synthesized, preserved 88% of its photocatalytic activity after five recyclability tests and had remarkable electron-hole separation activity, according to reusability tests and transient-photocurrent measurements. Also, the radical capture experiment suggested that superoxide and hydroxyl are important for porous NCO's photocatalytic activity. According to the findings of this research, the synthesis of ferromagnetic metal-doped and porous semiconductive materials has a great potential for azo dye breakdown, which makes it an efficient, cost-effective, and environmentally acceptable solution for the clean-up of polluted water.

Polyethylene glycol-modified mesoporous zerovalent iron nanoparticle as potential catalyst for improved reductive degradation of Congo red from wastewater

In this study, bare zero-valent iron nanoparticles (nZVI) have been modified using polyethylene glycol (PEG) of various molecular weight in a facile technique. The synthesized nZVI modified with PEG, M.W. of 600 and 6000 was denoted by nZVI-PEG600 and nZVI-PEG6000, respectively, and compared their catalytic activity towards the reductive degradation of Congo red (CR) using NaBH4.The existence of PEG layer surrounds the nZVI core was confirmed by several characterization tools, such as XRD, FTIR, FESEM and TEM. Herein, both nZVI-PEG600 and nZVI-PEG6000 exhibited remarkable removal efficiencies of 89.6% and 99.2% within 14 min of reaction time. The optimum reaction parameters were found to be as follows: 0.2 g L−1 catalyst dose and initial dye concentration of 2 × 10−5 molL−1 etc. Kinetic studies of dye degradation were investigated which follow pseudo-1st-order kinetics. The TOC analysis confirmed the complete mineralization of CR dye by nZVI-PEG6000 nanocatalyst. GCMS analysis of plausible degraded products was performed to elucidate a probable mechanistic pathway of CR degradation. Further, we have investigated the degradation of two anionic dyes mixture, i.e., CR and methyl orange (MO) using best catalyst, i.e., nZVI-PEG6000.

Synthesis of binary metal doped CeO2 via the subcritical hydrothermal method for photo-mineralizing methyl orange dye

Herein, we adopted subcritical hydrothermal method to synthesize the copper and bismuth co-doped CeO2 (Ce0.92Cu0.04Bi0.04O2) nanostructure for water remediation application. Copper and Bismuth co-doping synergistically improved the current conductivity and light-harvesting capabilities of the co-doped CeO2 that is respectively confirmed through current-voltage and optical studies. The microstructural, compositional and morphological information of the as-synthesized photocatalyst were accessed through powder XRD, and electronics spectroscopic techniques. In terms of practical application, the as-prepared co-doped CeO2-based photocatalyst mineralized the anionic dye (methyl orange, MO) up to 95.79%, at the rate of 0.0314 min−1, in just 50 min of solar irradiation. Statistics show that our Ce0.92Cu0.04Bi0.04O2 photocatalyst is 2.32 times more effective at mineralizing MO dye, and its rate of dye mineralization is 5.5 times faster than a CeO2 photocatalyst. In addition, the Ce0.92Cu0.04Bi0.04O2 photocatalyst possesses exceptional robustness as it fully retains its photocatalytic activity after three consecutive reusability tests. Our doped photocatalyst's excellent dye mineralizing activities come from the way its hybrid nanostructure morphology, good current conductivity, visible-light-supported bandgap, and induced structural defects work together. This gives it a larger surface area, a faster charge transport rate, better light harvesting ability, and lower charge recombination efficiencies. The copper and bismuth co-doping in the CeO2 lattice have a positive effect on its photocatalytic properties, suggesting that it has the potential to be a light-driven catalyst for azo dyes degradation.

Front Cover: Continuous Flow Photooxidative Degradation of Azo Dyes with Biomass‐Derived Carbon Dots (ChemPhotoChem 5/2023)

The Front Cover image illustrates the degradation of water contaminants using carbon dots in continuous flow. The filament inside the light bulb represents the coiled continuous flow photoreactor used for the photooxidative degradation of azo dyes using as catalysts carbon dots derived from the hydrothermal treatment of fish waste in the presence of oxygen (represented by the luminescent dots and trail on the left). The system allowed complete mineralization of azo dyes in only 2 minutes under UV light irradiation. Cover design by Davide Brunelli and Carlotta Campalani. More information can be found in the Research Article by Jean-Christophe M. Monbaliu, Alvise Perosa and co-workers.

Activation of persulfate by TiO2 -Fe3 O4 nanocomposite for reactive red 198 degradation along with modeling and optimization approach

Background: Recently, sulfate radical-based photocatalytic processes have attracted significant interests because of unique advantages in pollutants purification. In this study, TiO2 -Fe3 O4 nanocomposites in the presence of persulfate and under ultraviolet light-emitting diode (UV-LED) irradiation were applied for reactive red 198 removal with a focus on the main operating parameters such as pH, persulfate molar concentration, irradiation time, and catalyst dosages in different initial concentrations. Methods: The nanoparticles were synthesized by co-precipitation technique. The X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) coupled with energy dispersive X-ray (EDX) and Fourier transform infrared spectroscopy (FTIR) analysis were used to evaluate TiO2 - Fe3 O4 nanocomposites. The response surface methodology (RSM) was employed for modeling and optimization. The kinetics and mechanisms of decolorization by sulfate and hydroxyl radicals were investigated. The mineralization of dye was evaluated using total organic carbon (TOC) analysis. Results: Modeling and optimization through RSM showed that the maximum decolorization of reactive red 198 is accursed an initial concentration of 10-50 mg/L was reached under UV-LED irradiation of 62- 85 min, persulfate concentration=0.8-1 mM, 0.19-0.3 g/L TiO2 -Fe3 O4 nanocomposites concentration, and pH=3. The kinetics of process was in agreement with pseudo-first order. The mineralization of reactive red 198 during the optimum conditions was determined at about 61.1% and 49.6%, meanwhile, the decolorization efficiency in the same conditions was approximately 98.1% and 87.6%, respectively. Conclusion: The use of TiO2 -Fe3 O4 nanocomposites under UV-LED irradiation in the presence of persulfate can be used as an efficient and promising method for dye removal from textile wastewater.

Eggshell powder as an efficient recyclable catalyst generates H2O2 prompted radicals for selective oxidative mineralization of crystal violet dye at room temperature

Eggshell powder (ESP) was explored as a selective heterogeneous catalyst for oxidative degradation of crystal violet (CV) dye in aqueous media in presence of H2O2 at room temperature. Natural but throw-away material ESP as a carbonate (CO32−) source facilitated the formation of carbonate anion radicals in presence of H2O2. Carbonate anion radicals (CO3•−), though a weaker oxidant than ∙OH radical, efficiently served as a selective oxidant. Selective degradation of CV dye in aqueous solution was confirmed from the quenching experiments. Synergistic effects of both the radicals (CO3•− and ∙OH) in the dye degradation process was experimentally verified. At a dose of 10 g/L of ESP, 91% removal of CV (initial concentration: 10 mg/L) was achieved in 60 min. The reaction kinetics followed first order rate model. Intermediate products formed during CV degradation and the extent of mineralization were confirmed from MALDI-TOF-MS and TOC analysis, respectively. The turnover number (TON) and turnover frequency (TOF) were obtained as 2.45 × 10−6 mol per g and 6.81 × 10−10 mol per g per second. A promising reusability was achieved up to seven cycles. The ESP catalyst used in this study was characterized by SEM, FTIR, XRD, XPS, BET surface area analysis, UV–visible DRS, XRF, and pHZPC analyses. The present work offers a novel facile but selective route for CV degradation and opens up newer possibilities for eggshell waste utilization as catalyst.

Rare earth and transition metal co-doped LaFeO3 perovskite and its CNTs reinforced nanohybrid for environmental remediation application

Herein, rare earth (Gd) and transition metal (Co) co-doped LaFeO3 [La1-xGdxFe1-yCoyO3, (x = 0.08, y = 0.05), LGFCO] perovskite and its carbon nanotube (CNT) reinforced nanohybrid (LGFCO@C) were prepared for the first time via a wet-chemical and post-ultrasonication method. The well-known physical and electronic studies, i.e., XRD, Raman, FTIR, and EDX, were carried out to confirm the doping and CNT reinforcement. The effects of adopted co-doping and reinforcing approaches on the morphology, surface area, conductivity, and band structure were also investigated via SEM, BET, I–V, and UV–vis studies. Due to its hybrid composition, adequate band gap (2.37 eV), greater surface area (105.6 m2 g−1), and superior electronic conductivity (4.432 × 10−1 Scm−1), the LGFCO@C catalyst has remarkable catalytic capabilities for the mineralization of the anionic dye phenol red (PR). Apart from doping, the CNTs reinforced with LGFCO perovskites greatly improved the nano-hybrid's light harvesting and catalytic activity. After only 1 h of exposure to solar radiation, LGFCO@C mineralized 91.6% PR dye with a constant rate value of 0.04 sec−1. A dose of 20 mg of LGFCO@C effectively mineralizes the PR dye in acidic media (pH = 3), according to an optimization study. Furthermore, scavenging tests validate that photo-generated electrons, holes, superoxide, and hydroxyl radicals form during the photocatalytic reaction and play their role in the PR dye mineralization process. The stability and reusability of the LGFCO@C catalyst were also evaluated for five cycles. Even after five successful reusability tests, the LGFCO@C catalyst lost only 11.4% of its activity. Our study indicates that integrating the maximum number of features into a single catalyst is a promising strategy and can open a new avenue in the field of photocatalysis.

Solar light driven degradation of textile dye contaminants for wastewater treatment – studies of novel polycationic selenide photocatalyst and process optimization by response surface methodology desirability factor

The unplanned anthropogenic activities and raced industrial revolution detrimentally causes serious threat to terrestrial and aquatic life. A high discharge of wastewater from industries using dyes affects living organisms and the environment. This paper presents studies on polycationic selenides (PCS) synthesized by hydrothermal methods for photocatalytic degradation of dyes. The synthesized PCS were confirmed by various characterization techniques such as FTIR, SEM, EDX, UV/Vis, and XRD. The FTIR spectra revealed characteristic band at 843, 548 cm−1, and 417 cm−1 due to the M − Se stretching and intrinsic stretching vibrations, respectively. The optical bandgap of polycationic selenide lies in the visible light region (2.36 eV). The SEM images showed that PCS has a spherical shape with an average crystallite size of 29.23 nm calculated from XRD data using Scherer's equation. The PCS has a point of zero charge (PZC) at pH 7. The efficiency of synthesized PCS photocatalyst was confirmed in terms of its activity towards Eosin (EY) and Crystal violet (CV) dyes mineralization. The photocatalytic degradation for EY and CV dyes at optimum conditions was 99.47% and 99.31% and followed second order reactions kinetics with 1.4314 and 0.551 rate constant, respectively. The polynomial quadratic model is the best-fitted response surface methodology (RSM) model having a maximum desirability factors value and significant terms, with R2 (0.9994) and adj R2 values (1.0).

Synthesis of nanostructured gadolinium doped mixed ferrite: A novel catalyst for the mineralization of textile dyes

Herein, cobalt-nickel mixed ferrite (Co0·5Ni0·5Fe2O4, CNFO) and gadolinium doped cobalt-nickel mixed ferrite (Co0·5Ni0.5Gd0.1Fe1·9O4, G-CNFO) materials have been synthesized at the nanoscale via the microemulsion technique. The physicochemical features of the CNFO and G-CNFO materials were examined by advanced structural (PXRD and FTIR), morphological (FESEM), elemental (EDX), and optical (UV/Vis and transient photocurrent) studies. Under visible light, the catalytic activity of CNFO and G-CNFO materials was compared using Congo red and Aniline blue dyes as model textile pollutants. The G-CNFO material showed better photocatalytic activity than CNFO material, as it eliminated almost 21% more dye than CNFO material under the same experimental conditions. In order to find the optimal parameter for the experiments, the variables affecting the catalytic properties of the G-CNFO material were investigated in considerable detail. These variables included pH, catalyst dosage, dye concentration, temperature, and irradiation time. Scavenging and transient photocurrent experiments were also carried out in order to determine the key reactive oxygen species and the formation of electron-hole pairs. The G-CNFO mineralized the Congo red dye almost three times faster than its counterpart and showed a negligible loss in its catalytic activity even after five successive catalytic cycles. The combined effects of the G-CNFO material's tuned band structure, high light harvesting abilities, reduced electron-hole recombination, and nanostructured morphology resulted in its enhanced photocatalytic activity.

Sun irradiated high efficient photocatalyst ZnO nanoparticles obtained by assisted microwave irradiation

In this research microwave assisted zinc oxide synthesis applied to methylene blue dye mineralization is reported. This technique strongly influences the presence of certain intrinsic defects that is similar to those obtained by techniques where a rich oxygen atmosphere is used. These defects play a strong role in photocatalysis, showing a short time (70 min) at 95.3 % efficiency in methylene blue degradation under direct sunlight irradiation. Through X-ray diffraction, crystallinity, and nanoparticle size (5 nm) were obtained, meanwhile the morphology and elemental composition was observed by Scanning Electron Microscopy and Energy-Dispersive X-ray respectively. Additionally, Ultraviolet–Visible and Photoluminescence methods complete the analysis letting calculate the band gap (3.5 eV) and the presence/contribution of intrinsic defects. Such defects are identified as direct and strong contributors to carrier’s concentration separation and alternatively provoking low recombination levels, which is a characteristic desired in organic materials mineralization.

Photocatalytic Degradation of Crystal Violet Dye under Visible Light by Fe-Doped TiO2 Prepared by Reverse-Micelle Sol-Gel Method.

A reverse-micelle sol-gel method was chosen for the preparation of Fe-doped TiO2 samples that were employed in the photodegradation of the crystal violet dye under visible light irradiation in a batch reactor. The dopant amount was varied to assess the optimal photocatalyst composition towards the target dye degradation. The photocatalysts were characterized through a multi-technique approach, envisaging XRPD and QPA as obtained by Rietveld refinement, FE-SEM analysis, DR UV-vis spectroscopy, N2 adsorption/desorption isotherms measurement at -196 °C, ζ-potential measurement, and XPS analysis. The physical-chemical characterization showed that the adopted synthesis method allows obtaining NPs with uniform shape and size and promotes the introduction of Fe into the titania matrix, finally affecting the relative amounts of the three occurring polymorphs of TiO2 (anatase, rutile and brookite). By increasing the Fe content, the band gap energy decreases from 3.13 eV (with undoped TiO2) to 2.65 eV (with both 2.5 and 3.5 wt.% nominal Fe contents). At higher Fe content, surface Fe oxo-hydroxide species occur, as shown by DR UV-vis and XP spectroscopies. All the Fe-doped TiO2 photocatalysts were active in the degradation and mineralization of the target dye, showing a TOC removal higher than the undoped sample. The photoactivity under visible light was ascribed both to the band-gap reduction (as confirmed by phenol photodegradation) and to dye sensitization of the photocatalyst surface (as confirmed by photocatalytic tests carried out using different visible-emission spectra LEDs). The main reactive species involved in the dye degradation were determined to be positive holes.

Experimental and ab initio studies of Co-doped ZnO nanophotocatalyst thin films for dye mineralization.

Pristine ZnO and Co-doped ZnO photocatalyst thin films were fabricated on a ceramic substrate by spray pyrolysis. The optical, morphological and structural properties of the fabricated nanophotocatalyst thin films were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy and Fourier transform infrared (FTIR) spectroscopy. Operational parameters, including dye concentration, oxidant concentration, irradiation time and pH for dye degradation, were optimized by response surface methodology (RSM). The maximum degradation obtained was 93% under ideal conditions, such as pH 7, 3 h of direct sunlight irradiation, 30 mM concentration of oxidant and 10 ppm concentration of dye (MB). The evaluation of the extent of degradation was done using the UV/visible spectrophotometry technique. The reusability of the fabricated thin film was examined under optimized conditions. Density functional theory (DFT) with the B3LYP/LanL2DZ method was used for the theoretical modelling of the fabricated nanomaterials. The optimized structure, theoretical band gaps, IR spectra and Raman spectra of the fabricated pristine ZnO and Co:ZnO nanophotocatalysts were determined.

Elevating pH and introducing SO42– to promote organic dye mineralization by UV/PDS process under high contents of Cl– conditions

Elevating pH and introducing SO42– to promote organic dye mineralization by UV/PDS process under high contents of Cl– conditions

Photocatalytic Degradation of Dye Acid Orange Seven on Titanium Dioxide Photocatalysts Immobilized on Stainless Steel Coated Layers: Role of Catalyst Loading and Ultrasonic Treatment

Supported titanium dioxide (TiO2) was investigated for potential application in photocatalytic degradation of dye acid Orange 7 in textile wastewater. Two commercial powder photocatalysts, Degussa (P25) and Precheza (AV01), were immobilized on stainless steel plates of dimensions (75 mm × 25 mm) through Electrophoretic Deposition Process (EPD) from aqueous colloidal suspensions of n-TiO2, c=10 g.L-1 produced in methanol. Two sets of coated layers were prepared - using ultrasonically treated TiO2 colloidal suspensions and without ultrasonic treatment. The prepared coated layers were fitted onto a four-hole photocatalytic reactor operating under batch-mode conditions. As a source of UV light, Sylvania LynxS, 11W UV lamps emitting light of wavelength between 320-400 nm with maximum wavelength at λ=355 nm was used. The current study aimed to evaluate the effect of ultrasonic treatment on the catalyst’s colloidal suspension and electrophoretic deposition loading (mg/cm2) on its surface area on the resultant photocatalytic degradation of dye Acid Orange 7. The photocatalytic degradation of the dye was monitored by changes in dye absorbance for 120 minutes at an interval of 30 minutes. Changes in dye concentration were determined by ultraviolet spectrophotometry at λ = 485 nm. The initial concentration of dye Acid Orange 7 used in the experiments was c=1×10-4 mol. L-1. The findings show that 61.1 % of dye mineralization was achieved after 120 minutes of photocatalytic degradation. The optimum catalytic loading for maximum photocatalytic degradation was determined at 0.75 mg/cm2 for the two commercial powder catalysts - TiO2 (P25/AV01) in ultrasonically treated TiO2 (P25) and non-ultrasonically treated TiO2 (AV01). Ultrasonic treatment of TiO2 (P25) colloidal suspensions before immobilisation positively influenced its photocatalytic activity, whereas ultrasonic treatment negatively affected the photoactivity of TiO2 (AV01). Overall, TiO2 (AV01) proved to be more efficient by 28.6%, compared to TiO2 (P25). The results show the potential application of UV-TiO2 treatment model in the remediation of coloured dye Acid Orange textile wastewater.

Solar light-based photocatalytic removal of CV and RhB dyes using Bi and Al doped SrFe12O19 NPs and antibacterial properties

The SrBixAlxFe12-2xO19 (x = 0.0–1.0) nano-hexaferrites were prepared via facile micro-emulsion method and ferroelectric, dielectric, magnetic, photocatalytic and antibacterial properties were investigated based on doping contacts. The XRD analysis confirmed the hexagonal single-phase material with P63/mmc space group. P-E loops indicated the higher polarization and coercivity values for doped materials. VSM results showed that maximum and remnant magnetizations were quite high for undoped material while coercivity was low than doped hexaferrite. Optical band gap was reduced to 1.63 eV from 2 eV (pristine) for highly doped composition. PL intensity showed a sharp decline with doping, which indicated the better inhibition of charge carriers on doping. The photo-catalytic activity of pristine and the doped SrBixAlxFe12-2xO19 was investigated using Crystal Violet and Rhodamine B dyes under solar irradiation. SrAlxBixFe12-2xO19 (x = 1.0) exhibited improved catalytic efficiency and up to 83 and 86 (%) removal of CV and RhB dyes with rate constant of 0.047 and 0.048 (min−1), respectively. Highly doped ferrite also showed enhanced bactericidal action against S. aureus and E. coli strains. Superior mineralization of textile dyes and good antimicrobial activity of Bi and Al doped strontium nano-hexaferrites make such material as crucial candidate for solar light responsive photocatalytic and antimicrobial applications.

Solar-light-driven and magnetically recoverable doped nano-ferrite: An ideal photocatalyst for water purification applications

Semi-conductive photocatalysts have received a lot of interest for water treatment applications. This is due to their high efficiency and cost-effective nature. The challenge for material scientists is to design a semi-conductive material-based photocatalyst capable of protecting the environment and cleaning up hazardous waste water. The current study is centered on developing nanostructured Mn-doped cobalt ferrite as a photocatalytic material that is magnetically recyclable, active in visible light, stable at high temperatures, and has high conductivity. Then, using XRD, EDX, FT-IR, and SEM examination, the crystal structure, chemical composition, chemical functionality, and morphology of the wet-chemically synthesized undoped and Mn-doped ferrite samples were compared. Through the completion of TGA, I-V, UV–Vis, impedance, and transient photocurrent experiments, the requisite characteristics of the as-prepared ferrite materials, such as thermal stability, electrical conductivity, light-harvesting capability, charge transport performance, and charge separation efficiency, were also investigated. We used undoped and Mn-doped cobalt ferrite materials for the visible-light-driven crystal violet (CV) dye mineralization. However, the Mn-doped cobalt ferrite sample did a pretty good job as a photocatalyst and mineralized 95.8% CV dye (10 ppm) in just 40 min at a rate of 0.058 min−1. The doped ferrite sample was completely recovered from the photocatalytic system after each recyclability test due to its magnetic characteristics. Even after the four consecutive cycles, it maintained 97.2% of its original photocatalytic activity. The current work looks into the possibility of combining a semi-conductive catalyst's surface, magnetic, mechanical, and optical functions to clean up wastewater cost-effectively.

Coupling ZnO with CuO for efficient organic pollutant removal.

Fabrication of heterojunction semiconductors for the photodegradation of toxic organic dyes under sunlight exposure has earned significant recognition from researchers nowadays. On that account, we have synthesized and explored a comparative photodegradation study of ZnO/CuO nanocomposite with ZnO and CuO nanoparticles. ZnO and CuO nanoparticles have been synthesized by biosynthesis methods usingFicus benghalensisleaf extract. As-synthesized ZnO and CuO nanoparticles have been further utilized for the synthesis of ZnO/CuO nanocomposite by the mortar pestle crushing/milling method. Both biosynthesis methods and mortar pestle crushing/milling methods are simple, low-cost, and environmentally friendly. Structural, optical, and morphological analysis of all the synthesized nanomaterials havebeen doneby powder X-ray diffraction (PXRD), scanning electron microscopy (SEM),transmission electron microscopy (TEM),Brunauer-Emmett-Teller (BET),field emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDS), fourier transform infrared spectroscopy (FTIR), and UV-visible spectroscopy.PXRD data reveal that synthesized ZnO nanoparticles are in the hexagonal wurtzite phase, CuO nanoparticles in the monoclinic phase, and ZnO/CuO nanocomposite in the hexagonal wurtzite as well as in monoclinic phase. FE-SEM and TEM images of ZnO/CuO nanocomposite reveal the nanorod-shaped morphology along with micro-sized and nano-sized flakes. The BET analysis shows the surface areas 18.128 m2/g for ZnO nanoparticles, 16.653 m2/g for CuO nanoparticles, and 19.580 m2/g for ZnO/CuO nanocomposite, respectively. Theenergyband gap values of ZnO/CuO nanocomposite are obtained 3.13eV for ZnO and 2.76eV for CuO, respectively. The photocatalytic behaviors of all the synthesized nanomaterialsareexamined against aqueous dye solutions of methylene blue (MB), rhodamine B (RhB), and methyl orange (MO) under sunlight irradiation. The results reveal that the photocatalytic degradation efficiency of ZnO/CuO nanocompositehasbeen found higher than with ZnO and CuO nanoparticles for all the dyes. Also, all the synthesized nanomaterialsindicatehigher photocatalytic degradation efficiency for methylene blue dye among allthreedyes. The kinetics of photodegradation of all the dye solutions has also been investigated in the presence of ZnO, CuO, and ZnO/CuO photocatalysts separately. The results exhibit that rate constant values for all the dyes are higher with ZnO/CuOnanocompositethan with ZnO and CuOnanoparticles.ZnO/CuO nanocomposite demonstrates degradation efficiency for MB dye99.13%, for RhB80.21%, and for MO67.22%after 180min of sunlight exposure.ZnO/CuO nanocomposite and ZnO and CuO nanoparticles also show thebestreusability and stability up to three cycles for photocatalytic degradation of MB dyes amongall the dyes.Therefore, green synthesized ZnO/CuO nanocomposite could be used asan efficientphotocatalyst for the degradation of various toxic dyes.The mineralization of different dyes using ZnO/CuO nanocomposite has been examined by FTIR analysis. Furthermore, the mineralizationof MB dye has been done by total organic carbon (TOC)measurements.