Facile fabrication of mpg-C3N4/Ag/ZnO nanowires/Zn photocatalyst plates for photodegradation of dye pollutant

Degradation of organic Pollutant by Using of BiVO4-NiFe2O4 Heterostructure Photocatalyst under Visible Light Irradiation: Assessment of Detoxicity Study Using Cirrhinus mrigala

The current study mainly concentrates on the photocatalytic activity of composite nanomaterial of BiVO4 (BVO), NiFe2O4 (NFO), and BiVO4-NiFe2O4 (BVO-NFO) under visible light. Among these, BVO-NFO composite degrades crystal violet dye within 60 min with a percentage degradation of 95.65% under visible light illumination. The BVO-NFO composite exhibits better photodegradation performance, which can be attributed to the effective light absorption and reduced recombination of the photoexcited charge carriers. Additionally, by applying a magnetic field, the BVO-NFO composite can be magnetically recovered by using the magnet for subsequent recycling. The synthesized composite was characterized using optical techniques like X-ray diffraction, ultraviolet diffuse reflectance spectroscopy, scanning electron microscopy, Brunauer-Emmett-Teller, and energy dispersive X-ray analysis. The effect of dye, before and after degradation, on vital organs of fish species was examined such as fish gill (pulmonary-toxicity), fish liver (hepato-toxicity), fish kidney (renal toxicity), fish brain (neural toxicity), and fish muscle (myopathy). This work offers a clear and practical method for designing a highly crystalline semiconductor photocatalyst for dye degradation and the remediation of industrial wastewater.

Metal-Free C60-Doped Mesoporous Carbon Nitride Drives Red-Light Photocatalysis

The pursuit of novel strategies for synthesizing high-performance nanostructures of graphitic carbon nitride (g-C3N4) has garnered increasing scholarly attention in the field of photocatalysis. Herein, we have successfully designed a metal-free photocatalyst by integrating mesoporous carbon nitride (mpg-C3N4) and C60 through a straightforward and innovative method, marking the first instance of such an achievement. Under red light, the C60/mpg-C3N4 composite exhibited a significantly accelerated rhodamine B (RhB) photodecomposition rate, surpassing bulk g-C3N4 by more than 25.8 times and outperforming pure mpg-C3N4 by 7.8 times. The synergistic effect of C60 and the mesoporous structure significantly enhanced the photocatalytic performance of g-C3N4 by adjusting its electronic structure, broadening the light absorption range, increasing the active sites, and reducing the recombination of photogenerated carriers. This work presents a promising avenue for harnessing a metal-free, stable, efficient photocatalyst driven by red light, with potential for enhancing solar energy utilization in environmental remediation.

Facile synthesis of efficient MoS2-coupled graphitic carbon nitride Z-scheme heterojunction nanocomposites: photocatalytic removal of methylene blue dye under solar light irradiation

Among different types of semiconductor photocatalysts, MoS2 hybridized with graphitic carbon heterojunction has developed the most promising "celebrity" due to its static chemical properties, suitable band structure, and facile synthesis. Physiochemical and surface characterizations were revealed with structural, electronic, and optical analysis. Diffused reflectance spectroscopy evidenced the energy band gap tailoring from 2.62 eV for pure g-C3N4 and 1.68 eV for MoS2 to 2.12 eV for the hybridized heterojunction nanocomposite. Effective electron/hole pair separation, rise in redox species, and great utilization of solar range because of band gap modifying leading to greater degradation efficacy of g-C3N4/MoS2 heterojunction. The photocatalytic degradation with MoS2/g-C3N4 heterojunction catalyst to remove methylene blue dye was remarkably enriched and much higher than g-C3N4. By carefully examining the stimulus aspects, a probable mechanism is suggested, assuming that the concurring influence of MoS2 and g-C3N4, the lesser crystallite size, and more solubility in aquatic solution furnish the efficient e--h+ pair separation and tremendous photocatalytic degradation activity. This work delivers a novel idea to improve the efficient MoS2/g-C3N4 heterojunction for improved photocatalytic degradation in environmental refinement.

Silver-infused TiO2 nanowires and unveiling their potential for superior wastewater dye remediations

Silver infused ultrathin TiO2 nanowires (NWs) were synthesized via a single step solvothermal approach. The crystallinity, structure, and morphology were determined to understand the physicochemical nature of the nanocomposites. The catalytic efficiency of the newly synthesized nanocatalysts was tested for the textile waste treatment taking methylene blue (MB) as model pollutant under solar light irradiations. Nearly 96% photodegradation efficiency for MB was achieved within 20 min. Furthermore, the recyclability of the photocatalyst was also studied, and the material remained stable and effective up to four consecutive runs. RESEARCH HIGHLIGHTS: Precise size-controlled synthesis of Ag-incorporated titania nanowires (ATNWs) Controlled aspect ratios, with tunable lengths and diameters (100-3 nm) via precursor and surfactant optimization Demonstrated ATNWs' efficiency in degrading toxic dye, methylene blue (MB) 96% photodegradation efficiency for MB achieved within 20 min using 3 nm thick annealed TiO2 NWs Recyclability efficiency of photocatalyst, which remained stable and effective for up to four consecutive runs.

In Situ Growth of CuBi2O4/Bi2O3 Z-Scheme Heterostructures for Bifunctional Photocatalytic Applications

In this study, we present an in situ solvothermal approach for synthesizing a highly efficient bifunctional CuBi2O4/Bi2O3 composite catalyst for applications in H2 production and the removal of organic pollutants. Various characterization techniques, including XRD, UV-vis DRS, SEM, TEM, and EIS, were used to characterize the prepared catalyst. Density functional theory calculations confirmed a Z-scheme mechanism, revealing the charge transfer mechanism from the Bi2O3 surface to the CuBi2O4 surface. The composite exhibited a photocurrent of 2.83 × 104 A/cm2 and a hydrogen production rate of 526 μmolg-1h-1 under natural sunlight. Moreover, the catalyst demonstrated efficient degradation of RhB up to 58% in 120 min under 50 W LED illumination. Additionally, multiple recycling tests confirmed its high stability and recyclability, making it a promising candidate for various applications in the field of photocatalysis.

Synthesis, magnetic properties, biotoxicity and potential mechanism of modified nano zero-valent iron for decolorization of dye wastewater

SiO2-coated nano zero-valent iron (nZVI) has emerged as a fine material for the treatment of dye wastewater due to its large specific surface area, high surface activity, and strong reducibility. However, the magnetic properties based on which SiO2-coated nZVI (SiO2-nZVI) could effectively separate and recover from treated wastewater, and the biotoxicity analysis of degradation products of the dye wastewater treated by SiO2-nZVI remain unclear. In this study, SiO2-nZVI was synthesized using a modified one-step synthesis method. The SiO2-nZVI nanoparticles were characterized using Transmission electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, Fully automatic specific surface and porosity analyzer, Vibrating sample magnetometer, and Zeta potential analyzer. The removal rate of methyl orange (MO) by SiO2-nZVI composite reached 98.35% when the degradation performance of SiO2-nZVI treating MO was optimized. Since SiO2-nZVI analysed by magnetic hysteresis loops had large saturation magnetization and strong magnetic properties, SiO2-nZVI exhibited excellent ferromagnetic behaviour. The analysis of the degradation products showed that the MO treated by SiO2-nZVI was converted into a series of intermediates, resulting in reducing the toxicity of MO. The potential mechanism of MO degradated by SiO2-nZVI was speculated through degradation process and degradation kinetics analysis. Overall, the SiO2-nZVI composite may be regarded as a promising catalyst for decolorization of dye wastewater.

High-Efficiency Ag-Modified ZnO/g-C3N4 Photocatalyst with 1D-0D-2D Morphology for Methylene Blue Degradation

Photocatalysts with different molar ratios of Ag-modified ZnO to g-C3N4 were prepared through an electrostatic self-assembly method and characterized through techniques such as X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. The resulting Ag-ZnO/g-C3N4 photocatalysts exhibited a unique 1D-0D-2D morphology and Z-type heterojunction. Moreover, g-C3N4 nanosheets with large layer spacing were prepared using acid treatment and thermal stripping methods. The Z-type heterostructure and localized surface plasmon resonance effect of Ag nanowires enabled high-speed electron transfer between the materials, while retaining large amounts of active substances, and broadened the light response range. Because of these features, the response current of the materials improved, and their impedance and photoluminescence reduced. Among the synthesized photocatalysts, 0.05Ag-ZnO/g-C3N4 (molar ratio of g-C3N4/ZnO: 0.05) exhibited the highest photocatalytic performance under UV-visible light. It degraded 98% of methylene blue in just 30 min, outperforming both g-C3N4 (21% degradation in 30 min) and Ag-ZnO (84% degradation in 30 min). In addition, 0.05Ag-ZnO/g-C3N4 demonstrated high cycling stability.

Preparation and characterization of sulphur and zinc oxide Co-doped graphitic carbon nitride for photo-assisted removal of Safranin-O dye

Recently, there has been significant interest in photocatalytic reactions involving graphitic carbon nitride (g-C3N4) due to its sp2-hybridized carbon and nitrogen content and it is an ideal candidate for blending with other materials to enhance performance. Here, we have synthesized and analyzed both doped and undoped g-C3N4 nanoparticles. Specifically, we co-doped sulfur (S) into g-C3N4, integrated it with ZnO particles, and investigated the photocatalytic potential of these nanocomposites to remove Safranin-O dye. The initial step involved the preparation of pure g-C3N4 through calcination of urea. Subsequently, S-g-C3N4 was synthesized by calcining a mixture of urea and thiourea with a 3 : 1 ratio. Finally, the ZnO-S-g-C3N4 composite was synthesized using the liquid exfoliation technique, with distilled water serving as the exfoliating solvent. These samples were characterized by advanced techniques, including UV-Vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR), X-ray Diffraction (XRD), energy dispersive X-ray (EDX) and scanning electron microscopy (SEM), to assess their crystallinity, morphology, optical properties, and phase purity. Subsequently, these nanocomposites were employed in catalytic and photocatalytic processes to remove the Safranin-O dye (SO). The results highlighted the formation of Z-scheme junction responsible for ZnO-S-g-C3N4's significant performance improvement. The comparison of results demonstrated that S-g-C3N4 and ZnO-S-g-C3N4 composites revealed an effective removal of Safranin-O dye in the presence of UV-light as compared to pure g-C3N4, as it was attributed to the phenomenon of improved separation of photogenerated charge carriers as a result of heterojunction formation between S-g-C3N4 and ZnO interfaces. In addition to improving photocatalytic performance, this study presents a facile route for producing ZnO-S-g-C3N4 composite with superior adsorption capabilities and selectivity.

The Synthesis of carbon dots//zincoxide (CDs/ZnO-H400) by using hydrothermal methods for degradation of ofloxacin antibiotics and reactive red azo dye (RR141)

The development of photocatalytic powders to remove contaminants from air solutions is an important field of research in the field of environmental conservation. CD/ZnO-H400, a heterogeneous photocatalytic production, is utilized to degrade the reactive red dye and the antibiotic ofloxacin found in wastewater. This study explains the synthesis of carbon dots (CDs) derived from coconut air and zinc oxide (ZnO) using a hydrothermal method at a temperature of 180 °C with a duration of 4 h and subsequently calcinated at a 400 °C temperature for 4 h. This shows a significant improvement in photocatalytic performance due to improved delivery efficiency at the interface. The cost-efficient use of solar energy allows the comprehensive elimination of harmful pollutants through detoxification. The removal of the contaminant takes place through the first-order reaction, with RR141 showing the highest constant rate at 0.03 min-1, while ofloxacin has a constant speed at 0.01 min-1. The photocatalytic stability is measured after five cycles. The study also tested the impact of sunlight on degradation, showing a degrading rate of 98% for RR141 and 96% for ofloxacin. This study displays a new catalyst powder synthesized from carbon dots derived from the air, coconut and ZnO, showing remarkable photoactivity to completely remove harmful dyes and antibiotics from the surrounding environment.

Ultrasonic processing of WO3 nanosheets integrated Ti3C2 MXene 2D-2D based heterojunctions with synergistic effects for enhanced water splitting and environmental remediation

This article describes a straightforward chemical procedure that involves hydrothermal and ultrasonic treatments to create a new 2D/2D ultrathin WO3/Ti3C2 heterojunctions. The features of the fabricated heterojunctions were characterized and examined by field emission electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), optical absorption spectroscopy (UV-Vis). By photodegrading an organic dye under the influence of visible light, the photocatalytic degradation capabilities of the heterojunctions were also investigated. The performance of WO3/Ti3C2 was superior to that of bare WO3, with a removal rate of 94% and a kinetic rate constant (k) that was approximately 3 times that of WO3. The creation of 2D/2D heterojunction was observed to encourage the spatial charge separation and increase the surface reactive sites, to result with the increased photocatalytic activity in WO3/Ti3C2 heterojunction. The photocurrent values discovered through photoelectrochemical studies further indicated Ti3C2's active function in enhancing water-splitting performance. The impedance analysis examined by an electrochemical method revealed that heterojunctions might be helpful in accelerating the migration of charges quickly to get the outcomes seen.

Hydrothermal synthesis of V2O5/TiO2 decorated graphitic carbon nitride nanocomposite for biomolecule oxidation inhibition and dye degradation applications

Oxides of vanadium, titanium and graphitic carbon nitride (g-C3N4) are well known for their catalytic activities. In order to achieve synergic catalytic effects, a novel nanocomposite (NC) i.e. V2O5/TiO2/g-C3N4 has been synthesized by a very simple, ecofriendly and nonhazardous hydrothermal method. The fabricated NC was characterized employing UV-Visible, FTIR, SEM, and XRD techniques. UV-Visible and FTIR analysis indicated the formation of the nanocomposite and XRD analysis confirmed the association of V2O5 and TiO2 with g-C3N4 in nanocomposite. SEM study indicated the hetero-structure of NC having size ranging from 50 to 80 nm and it was found having hexagonal crystallite structure. The synthesized nanocomposite exhibited excellent scavenging of free radicals DPPH● (91%) and ABTS●+ (64%) that are responsible for the oxidation of biomolecules. Therefore, NC can be claimed having biomolecule oxidation protective potential. In addition, photocatalytic ability for the degradation of methylene blue (MB) and methyl orange (MO) was also achieved up to 94% and 89% respectively. The synthesized novel nanocomposite exhibited excellent potential to remove free radicals and dyes from aqueous medium which can be further used for the environmental remediation.

Visible light enhanced photocatalytic degradation of organic pollutants with SiO2/g-C3N4 nanocomposite for environmental applications

The development of eco-friendly photocatalysts is gaining attention as an effective approach for degrading organic pollutants. In the present study, the composite materials are composed of various components with varying structures that combine to enhance their characteristics and widen their applications. This work uses the hydrothermal method for the fabrication of a novel and steady SiO2/g-C3N4 photocatalyst. The amount of SiO2 was fixed, and graphitic carbon nitride (g-C3N4) was varied in the ratio (1:x, where x = 1, 2, 3) and abbreviated as SCN1, SCN2, and SCN3. The optical properties, surface morphology, and structural analysis of the prepared nanocomposites were studied using various techniques such as FTIR, TGA, X-ray diffraction, and ultraviolet-visible spectroscopy. The results show that SCN2 nanocomposites significantly improved the photocatalytic activity, with a degradation efficiency of 70% for auramine O and 84.6% for xylenol orange dye under visible light irradiation, which is a result of their large surface area and efficient electron-hole separation rate.

Facile and Sustainable Synthesis of ZnO Nanoparticles: Effect of Gelling Agents on ZnO Shapes and Their Photocatalytic Performance

The present work involves investigating an unexplored soft-chemical method for synthesizing nanostructured ZnO through biopolymer gelation. Our objective was to exploit (i) the difference in the gelation mechanism of four tested biopolymers, namely, alginate, chitosan, carboxymethylcellulose (CMC), and pectin and (ii) numerous experimental parameters that govern this process in order to allow the control of the growth of nanostructured ZnO, with a view to using the prepared oxides as photocatalysts for the oxidation of the Orange G dye. So, the effect of biopolymer's nature on the microstructural, morphological, and textural properties was examined by thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field-emission gun-scanning electron microscopy-high resolution (FEG-SEM) with energy-dispersive spectrometry (SEM-EDS), ultraviolet-visible (UV-vis) spectroscopy, and N₂ adsorption/desorption. As-prepared oxides were crystallized in a hexagonal wurtzite structure, with a clear difference in their morphologies. The sample prepared by using chitosan has a specific surface area of around 36.8 m²/g in the form of aggregated and agglomerated nanostructured minirods and thus shows the best photocatalytic performance with 99.3% degradation of the Orange G dye in 180 min.

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 using Ficus benghalensis leaf 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 have been done by 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. The energy band gap values of ZnO/CuO nanocomposite are obtained 3.13 eV for ZnO and 2.76 eV for CuO, respectively. The photocatalytic behaviors of all the synthesized nanomaterials are examined 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 nanocomposite has been found higher than with ZnO and CuO nanoparticles for all the dyes. Also, all the synthesized nanomaterials indicate higher photocatalytic degradation efficiency for methylene blue dye among all three dyes. 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/CuO nanocomposite than with ZnO and CuO nanoparticles. ZnO/CuO nanocomposite demonstrates degradation efficiency for MB dye 99.13%, for RhB 80.21%, and for MO 67.22% after 180 min of sunlight exposure. ZnO/CuO nanocomposite and ZnO and CuO nanoparticles also show the best reusability and stability up to three cycles for photocatalytic degradation of MB dyes among all the dyes. Therefore, green synthesized ZnO/CuO nanocomposite could be used as an efficient photocatalyst for the degradation of various toxic dyes. The mineralization of different dyes using ZnO/CuO nanocomposite has been examined by FTIR analysis. Furthermore, the mineralization of MB dye has been done by total organic carbon (TOC) measurements.

Photocatalytic Degradation of Methylene Blue Using N-Doped ZnO/Carbon Dot (N-ZnO/CD) Nanocomposites Derived from Organic Soybean

This study reports on successful synthesis of carbon dots (CDs), nitrogen-doped zinc oxide (N-ZnO), and N-ZnO/CD nanocomposites as photocatalysts for degradation of methylene blue. The first part was the synthesis of CDs utilizing a precursor from soybean and ethylenediamine as a dopant by a hydrothermal method. The second part was the synthesis of N-ZnO with urea as the nitrogen dopant carried out by a calcination method in a furnace at 500 °C for 2 h in an N2 atmosphere (5 °C min-1). The third part was the synthesis of N-ZnO/CD nanocomposites. The characteristics of CDs, N-ZnO, and N-ZnO/CD nanocomposites were analyzed through Fourier transform infrared (FTIR), UV-vis absorbance, photoluminescence (PL), high-resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), thermal gravimetry analysis (TGA), field-emission scanning electron microscopy energy-dispersive spectroscopy (FESEM EDS), X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET) analysis. Based on the HR-TEM analysis, the CDs had a spherical shape with an average particle size of 4.249 nm. Meanwhile, based on the XRD and HR-TEM characterization, the N-ZnO and N-ZnO/CD nanocomposites have wurtzite hexagonal structures. The materials of N-ZnO and N-ZnO/CD show increased adsorption in the visible light region and low energy gap E g. The E g values of N-ZnO and N-ZnO/CDs were found to be 2.95 and 2.81 eV, respectively, whereas the surface area (S BET) values 3.827 m2 g-1 (N-ZnO) and 3.757 m2 g-1(N-ZnO/CDs) belonged to the microporous structure. In the last part, the photocatalysts of CDs, N-ZnO, and N-ZnO/CD nanocomposites were used for degradation of MB (10 ppm) under UV-B light irradiation pH = 7.04 (neutral) for 60 min at room temperature. The N-ZnO/CD nanocomposites showed a photodegradation efficiency of 83.4% with a kinetic rate of 0.0299 min-1 higher than N-ZnO and CDs. The XRD analysis and FESEM EDS of the N-ZnO/CDs before and after three cycles confirm the stability of the photocatalyst with an MB degradation of 58.2%. These results have clearly shown that the N-ZnO/CD nanocomposites could be used as an ideal photocatalytic material for the decolorization of organic compounds in wastewater.

Control of particle growth and enhancement of photoluminescence, adsorption efficiency, and photocatalytic activity for zinc sulfide and cadmium sulfide using CoAl-layered double hydroxide system

The fabrication of zinc sulfide (ZnS) and cadmium sulfide (CdS) hybrids was carried out by the sulfidization of Zn(II) or Cd(II) adsorbed in dodecylsulfate modified CoAl-layered double hydroxide through solid-liquid reaction. The TEM images showed the nanocrystals of ZnS (2.61 nm) or CdS (3.29 nm) orderly distributed on the nanosheets. The BET surface area of ZnS (1.13 m²/g) and CdS (0.78 m²/g) was largely improved by intercalating in the interlayer space of CoAl-layered double hydroxide system (15-20 m²/g). The spectroscopic observations further confirmed the formation of ZnS or CdS nanoparticles in the hybrid as the evidence of the blue-shifted absorption onset (39-44 nm), and the increase of the photoluminescence intensity (3-4 times) relative to those of bare ZnS and CdS. The nanohybrids could be applicable as the adsorbent and photocatalyst on purifying wastewater contaminated with Congo red dye. By the adsorptive removal, the hybrids exhibited the maximum adsorption capacity of 216-234 mg/g, resulting from the effect of CoAl-layered double hydroxide. In addition, the photocatalytic degradation was completely conducted by using CdS hybrid with the rate constant of 0.0115 min^-1, because the host-guest and/or guest-guest interactions promoted the greater optical performance, and adsorption and photocatalytic efficiencies.

Construction of Waste Chalk Powder into mpg-C3N4-CaSO4 as an Efficient Photocatalyst for Dye Degradation under UV-Vis Light and Sunlight

In this article, we present the synthesis of calcium sulfate nanoparticles (CaSO₄ NPs) from waste chalk powder by the calcination method. These CaSO₄ NPs were utilized for the construction of a mesoporous graphitic carbon nitride-calcium sulfate (mpg-C₃N₄-CaSO₄) photocatalyst. Synthesized materials were confirmed by several characterization techniques. The photocatalytic performance of the synthesized samples was tested by the degradation of methylene blue (MB) in the presence of both UV-vis light and sunlight. The efficiency of photocatalytic degradation of MB dye using the optimized mpg-C₃N₄-CaSO₄-2 composite reached 91% within 90 min in the presence of UV-vis light with superb photostability and recyclability after five runs compared to individual mpg-C₃N₄ and CaSO₄ NPs and reached 95% within 120 min under sunlight. Histotoxicological studies on fish liver and ovary indicated that the dye containing the solution damaged the structure of the liver and ovary tissues, whereas the photodegraded solution of MB was found to be less toxic and caused negligible alterations in their typical structure similar to the control group.

Solar light-based advanced oxidation processes for degradation of methylene blue dye using novel Zn-modified CeO2@biochar

Herein, a novel nanocomposite, namely, Zn-modified CeO₂@biochar (Zn/CeO₂@BC), is synthesized via facile one-step sol-precipitation to study its photocatalytic activity towards the removal of methylene blue dye. Firstly, Zn/Ce(OH)₄@biochar was precipitated by adding sodium hydroxide to cerium salt precursor; then, the composite was calcined in a muffle furnace to convert Ce(OH)₄ into CeO₂. The crystallite structure, topographical and morphological properties, chemical compositions, and specific surface area of the synthesized nanocomposite are characterized by XRD, SEM, TEM, XPS, EDS, and BET analysis. The nearly spherical Zn/CeO₂@BC nanocomposite has an average particle size of 27.05 nm and a specific surface area of 141.59 m²/g. All the tests showed the agglomeration of Zn nanoparticles over the CeO₂@biochar matrix. The synthesized nanocomposite showed remarkable photocatalytic activity towards removing methylene blue, an organic dye commonly found in industrial effluents. The kinetics and mechanism of Fenton-activated dye degradation were studied. The nanocomposite exhibited the highest degradation efficiency of 98.24% under direct solar irradiation of 90 min, at an optimum dosage of 0.2 g l^-1 catalyst and 10 ppm dye concentration, in the presence of 25% (V/V) 0.2 ml (4 µl/ml) hydrogen peroxide. The hydroxyl radical generated from H₂O₂ during the photo-Fenton reaction process was attributed to the nanocomposite's improved photodegradation performance. The degradation process followed pseudo-first-order kinetics having a rate constant (k) value of 0.0274 min^-1.

Selective Adsorption of Direct Group Anionic Dyes on Layered Double Hydroxide-Chitosan Composites

In this research, the potential of M2+/Al intercalated chitosan has been evaluated and good ability to reduce dyes in an aqueous solution. M2+/Al intercalated chitosan was prepared by anion exchange method and coprecipitation in a nitrogen atmosphere. Selectivity adsorption was studied to maintain the ability of M2+/Al intercalated chitosan for particle size of direct dyes (direct green, direct red, and direct yellow). To evaluate the adsorption process, M2+/Al intercalated chitosan was conducted with kinetic, isotherm, and thermodynamic parameters. The kinetic data fitted well by pseudo-second order and isotherm fitted Langmuir isotherm with qmax obtained 294.11 and 322.58 mg/g for Zn/Al-chitosan and Mg/Al-chitosan, respectively. Copyright © 2023 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

Potassium Poly(heptazine imide) Coupled with Ti3C2 MXene-Derived TiO2 as a Composite Photocatalyst for Efficient Pollutant Degradation

The photocatalytic degradation of pollutants is an effective and sustainable way to solve environmental problems, and the key is to develop an efficient, low-cost, and stable photocatalyst. Polymeric potassium poly(heptazine imide) (K-PHI), as a new member of the carbon nitride family, is a promising candidate but is characterized by a high charge recombination rate. To solve this problem, K-PHI was in-situ composited with MXene Ti₃C₂-derived TiO₂ to construct a type-II heterojunction. The morphology and structure of composite K-PHI/TiO₂ photocatalysts were characterized via different technologies, including TEM, XRD, FT-IR, XPS, and UV-vis reflectance spectra. Robust heterostructures and tight interactions between the two components of the composite were verified. Furthermore, the K-PHI/TiO₂ photocatalyst showed excellent activity for Rhodamine 6G removal under visible light illumination. When the weight percent of K-PHI in the original mixture of K-PHI and Ti₃C₂ was set to 10%, the prepared K-PHI/TiO₂ composite photocatalyst shows the highest photocatalytic degradation efficiency as high as 96.3%. The electron paramagnetic resonance characterization indicated that the^·OH radical is the active species accounting for the degradation of Rhodamine 6G.

Heterogeneous photocatalytic activation of electrogenerated chlorine for the production of reactive oxygen and chlorine species: A new approach for Bisphenol A degradation in saline wastewater

UV-E-chlorination/hematite nanoparticles (UV/E-Cl/HNs) as a heterogeneous photocatalytic activation of electrogenerated chlorine was assessed for the degradation of bisphenol A (BPA) as a new approach based on the generation of reactive chlorine and oxygen species. The prepared sample was characterized using multiple techniques, such as XRD, FTIR, FESEM, EDS, and BET-BJH. An excellent decontamination efficiency of 99.4% was achieved within 40 min of electrolysis under optimum conditions (pH of 5, HNs dosage 100 mg/L, current density of 20 mA/cm², and NaCl concentration of 50 mM). The HOCl content was reduced more swiftly in the presence of ultraviolet (UV) irradiation and hematite, resulting in the production of oxidative radicals (i.e., ^•OH, Cl^•, and Cl₂^•-). The scavenging experiments also verified the vital role of these radicals in oxidative treatment. The UV/E-Cl/HNs process is readily supplied with hydroxyl radicals through several mechanisms. Bicarbonate ions showed a noticeable inhibitory impact, whereas nitrate and sulfate anions only slightly affected BPA degradation. The HNs were a recoverable and stable catalyst for six cycles. Furthermore, the ECOSAR program predicted that the UV/E-Cl/HNs can be labeled as an environmental-friendly process. Eventually, reasonable degradation pathways were proposed based on the identified by-products through experimental and theoretical approaches.

Photocatalytic degradation of chlorazol yellow dye under sunlight irradiation using Ce, Bi, and N co-doped TiO2 photocatalyst in neutral medium

Chlorazol yellow (CY) is a commonly used anionic, toxic, mutagenic, and potentially carcinogenic azo dye, which is menacing to the environment, aquatic system, food chain, and human health as well. To remove CY dye molecules from an aqueous medium, a series of Ce, Bi, and N co-doped TiO₂ photocatalysts were prepared by varying the composition of the dopants. Under sunlight irradiation, the resultant 5 wt% (Ce-Bi-N) co-doped TiO₂ composite catalyst was found to show the best catalytic activity. Hence, the required characterization of this catalyst was performed systematically using energy-dispersive X-ray spectroscopy (EDX), scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) techniques. From the thorough investigation, it is revealed that the CY molecules reached adsorption-desorption equilibrium onto the surface of the catalyst within 30 min following second-order kinetics. Herein, the catalyst attained 97% degradation when exposed to sunlight at neutral (pH ~ 7, [CY] = 5 mg L^-1) medium. The developed catalyst can destruct CY molecules with a maximum rate of 23.1 µg CY g^-1 min^-1 and the photodegradation kinetics follows first-order kinetics below 23.5 mg L^-1, a fractional order between 23.5 and 35.0 mg L^-1, and a zeroth order above 35.0 mg L^-1 of CY concentration. Finding from scavenging effect implies that [Formula: see text] and [Formula: see text] radicals have significant influence on the degradation. A suitable mechanism has been proposed with excellent stability and verified reusability of the proposed photocatalyst.

Cefotaxime degradation by the coupled binary CdS-PbS: characterization and the photocatalytic process kinetics

Increased water pollution due to discharging industrial/urban/hospital wastewater has been adopted to introduce/develop novel removal techniques/catalyst/adsorbent. The hexagonal (wurtzite) CdS and the cubic PbS nanoparticles (NPs) were synthesized, coupled, and supported onto clinoptilolite NPs (CNP). Then, the sample was characterized by X-ray powder diffraction (XRD), diffuse reflectance spectroscopy (DRS), Fourier transform infrared (FTIR), and a scanning electron microscope equipped with an energy dispersive X-ray analyzer (SEM-EDX) techniques. The average crystallite size for CdS NPs, PbS NPs, CNP, and CdS-PbS/CNP samples was obtained at about 24, 36, 27, and 14 nm using the Scherrer formula value of nanometer, by the W-H formula, 31, 17, 39, and 51, respectively. Only a detectable slope can be observed from the DRS spectra for CdS NPs at 591 nm corresponding to an Eg value of 2.1 eV. PbS NPs have a broad abruption peak that begins from the visible region and extends to the IR region of the light. A boosted photocatalytic activity of the supported binary catalysts towards cefotaxime (CT) was reached. An apparent first kinetic model was reached with a k-value of 0.021 min^-1 corresponding to the t_1/2 value of 33 min. A decreased COD trend for the photodegraded CT solutions was reached, and the chemical oxygen demand (COD) results in the Hinshelwood model showed a k-value of 0.016 min^-1, corresponding to a t_1/2 value of 43 min.

Highly efficient visible light active doped metal oxide photocatalyst and SERS substrate for water treatment

The development of efficient nanomaterials with promising optical and surface properties for multifunctional applications has always been a subject of novel research. In this work, the study of highly efficient TiO₂ nanorods (NRs) and Ta-doped TiO₂ NRs (Ta-TiO₂ NRs) synthesized by alkaline hydrothermal treatment followed by soaking treatment has been reported. NRs were investigated for their potential applications as recyclable/reproducible visible light active photocatalysts and surface-enhanced Raman scattering (SERS) substrates in wastewater treatment. NRs were characterized by various microscopic (scanning and transmission electron microscopy), spectroscopic (X-ray diffraction, X-ray photoelectron, UV-visible, photoluminescence, and Raman spectroscopy), and surface (Brunauer-Emmett-Teller) techniques. The NRs exhibited promising optical properties with a band gap of 2.95 eV (TiO₂ NRs) and 2.58 eV (Ta-TiO₂ NRs) showing excellent photo-degradation activities for methylene blue (MB) dye molecules under natural sunlight. Particularly, Ta-TiO₂ NRs showed enhanced response as visible light active photocatalysts in normal sunlight and also as SERS substrate attributed to the additional defects introduced by Ta doping. It could be explained by the combined effect of doping-induced enhanced visible light absorption and charge transfer (CT) properties of Ta-TiO₂ NRs. Furthermore, Ta-TiO₂ NRs were investigated for their long-term stability, reproducibility of the data, and recyclability in view of their potential applications in water treatment.

Advanced oxidation process: a sustainable technology for treating refractory organic compounds present in industrial wastewater

The world faces tremendous challenges and environmental crises due to the rising strength of wastewater. The conventional technologies fail to achieve the quality water that can be reused after treatment means "zero effluent" discharge of the industrial effluent. Therefore, now the key challenge is to develop improved technologies which will have no contribution to secondary pollution and at the same time more efficient for the socio-economic growth of the environment. Sustainable technologies are needed for wastewater treatment, reducing footprint by recycling, reusing, and recovering resources. Advanced oxidation process (AOP) is one of the sustainable emerging technologies for treating refractory organic contaminants present in different industrial wastewaters like textile, paper and pulp, pharmaceuticals, petrochemicals, and refineries. This critical review emerges details of advanced oxidation processes (AOPs), mentioning all possible permutations and combinations of components like ozone, UV, the catalyst used in the process. Non-conventional AOP systems, microwave, ultrasound, and plasma pulse assisted are the future of the oxidation process. This review aims to enlighten the role of AOPs for the mineralization of refractory organic contaminants (ROC) to readily biodegradable organics that cannot be either possible by conventional treatment. The integrated AOPs can improve the biodegradability of recalcitrant organic compounds and reduce the toxicity of wastewater, making them suitable for further biological treatment.

Anti-inflammatory and collagenation effects of zinc oxide-based nanocomposites biosynthesised with Mentha longifolia leaf extract

OBJECTIVE

The integration of nanomaterials and herbal medicine has led to the design of new nanocomposites, which are therapeutically more effective. The purpose of this study was to prepare different zinc oxide (ZnO)-based nanoparticles (NPs) via Mentha longifolia extract based on gauze linen fibre and study its effects on wound healing.

METHODS

The textural properties, morphology, thermal stability, purity, spectroscopic and phase structure of nanoparticles were investigated. Subsequently, male Wistar rats were subjected to wounds in six different treatment groups: Group I: control; group II: ZnO/W prepared in water (W); group III: ZnO/M synthesised with Mentha longifolia (M) extract; group IV: ZnO/copper(II) oxide (CuO)/M nanocomposite synthesised with M extract; group IV: treated with ZnO/silver (Ag)/M nanocomposite; group V: treated with ZnO/Ag/M nanocomposite; and finally, group VI: treated with ZnO/CuO/Ag/M nanocomposite. In all groups, the wounds were treated for 21 days with prepared samples. Every seven days, after measuring the decreasing rate of the wound size, tissue samples from each group were taken for histopathological analysis. The prepared tissue sections were assessed by haematoxylin and eosin staining for the formation of the epidermis, dermis and muscular tissue, and Masson's Trichrome staining for the formation of collagen fibres.

RESULTS

The results showed that the ZnO/CuO/Ag/M nanocomposite was a significantly more effective wound healing material in comparison with other samples (p<0.05).

CONCLUSION

In this study, the integration of ZnO/CuO/Ag nanocomposites with secondary metabolites of Mentha longifolia gave rise to a superior combination, which could support different phases of wound healing via the regulation of cytokines and growth factors in the course of healing.

The boosted photocatalytic effects of a zeolite supported CdS towards an antibiotic model pollutant: a brief kinetics study

In recent decades, increased world population and industrial activities explosively polluted our environment, especially the aquatic resources. This requires introducing/developing novel methods to decrease the pollution extent of such resources. Here, the hexagonal (wurtzite) CdS nanoparticles (NPs) were synthesized and supported onto ball-mill prepared clinoptilolite NPs (CNP). Samples were briefly characterized by X-ray powder diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscope equipped with an energy dispersive X-ray analyzer (SEM-EDX), and diffuse reflectance spectroscopy (DRS) techniques. The average crystallite size for CdS NPs and CdS-CNP samples was estimated to be about 9.0 nm and 12.3 nm (from the Scherrer formula) and about 19.7 and 17.5 nm (from the Williamson-Hall model), respectively. From the DRS spectra, the absorption wavelengths of 595 and 546 nm correspond to band gap energies of 2.08, and 2.27 eV was obtained for CdS NPs and CdS-CNP samples. The samples were then used in the photodegradation of cefotaxime (CT), and the results showed a boosted photocatalytic activity for CdS-CNP rather than CdS NPs. The photodegradation process obeyed the pseudo-first-order kinetic model, and the CdS and CdS-CNP catalysts obtained the k-values of 0.013 min^-1 and 0.023 min^-1. When the photodegraded CT solutions were used in COD experiments, the k-values changed to 0.011 min^-1 and 0.029 min^-1, respectively. The zeolite support is an eco-friendly natural zeolite with abundant deposits in Iran that yields a cost-effective method.

Synthesis of NiFe2O4/SiO2/NiO Magnetic and Application for the Photocatalytic Degradation of Methyl Orange Dye under UV Irradiation

NiFe2O4/SiO2/NiO magnetic was successfully synthesized using NiFe2O4, SiO2, and NiO as the core, interlayer, and shell, respectively. NiFe2O4/SiO2/NiO under UV light irradiation was used for photocatalytic degradation of methyl orange dye with different pH, catalyst dose, and initial dye concentration. This composite was characterized by X-ray Diffraction (XRD), Fourier Transform Infra-Red (FTIR), Scanning Electron Microscopy-Electron Dispersive X-ray Spectroscopy (SEM-EDs), Vibrating Sample Magnetometer (VSM), UV-Vis Diffuse Reflectance Spectroscopy (UV-Vis DRS), and Point of Zero Charge (pHpzc). The results showed that the composite is a superparamagnetic material with a saturation magnetization value of 44.13 emu/g. It also has a band gap of 2.67 eV with a pHpzc of 6.33. The optimum conditions for photocatalytic degradation were at pH of 4; 0.50 g/L catalyst dose, and 10 mg/L initial concentration. NiFe2O4/SiO2/NiO degradation efficiency to methyl orange dye was 95.76%. The photocatalytic degradation in different concentrations follows the pseudo-first-order, where the greater the concentration, the smaller the constant rate (k). After five cycles of repeated usage, NiFe2O4/SiO2/NiO has good catalytic performance as well as efficient and favourable of a recyclable photocatalyst. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

Comparative Study of Sonophotocatalytic, Photocatalytic, and Catalytic Activities of Magnesium and Chitosan-Doped Tin Oxide Quantum Dots

The present study demonstrates the hydrothermal synthesis of SnO₂ quantum dots (QDs) doped with different concentrations (2, 4 wt %) of magnesium (Mg) and a fixed amount of chitosan (CS). The obtained samples were investigated through a number of characterizations for optical analysis, elemental composition, crystal structure, functional group presence, interlayer spacing, and surface morphology. The XRD spectrum revealed the tetragonal structure of SnO₂ with no significant variations occurring upon the addition of CS and Mg. The crystallite size of QDs was reduced by incorporation of dopants. The optical absorption spectra revealed a red shift, assigned to the reduction of the band gap energy upon doping. TEM analysis proved that the few nanorod-like structures of CS overlapped with SnO₂ QDs, and agglomeration was observed upon Mg doping. The incorporation of dopants little enhanced the d-spacing of SnO₂ QDs. Moreover, the synthesized nanocatalyst was utilized to calculate the degradation percentage of methylene blue (MB) dye. Afterward, a comparative analysis of catalytic activity, photocatalytic activity, and sonophotocatalytic activity was carried out. Notably, 4% Mg/CS-doped QDs showed maximum sonophotocatalytic degradation of MB in basic medium compared to other activities. Lastly, the prepared nanocatalyst was found to be efficient for dye degradation in any environment and inexpensive.

Boosted photocatalytic effect of binary AgI/Ag2WO4 nanocatalyst: characterization and kinetics study towards ceftriaxone photodegradation

In modern chemistry, great interest has been paid to introducing outstanding photocatalysts for degrading organic pollutants. Herein, a highly efficient binary AgI/Ag₂WO₄ photocatalyst was prepared from AgI and Ag₂WO₄ nanoparticles (NPs) and characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), electrochemical impedance spectroscopy (EIS), and Fourier transform infrared (FT-IR) techniques. In the Scherrer model, the average crystallite sizes of 34.9, 42.0, and 24.1 nm were estimated for the AgI, Ag₂WO₄, and the binary catalyst, while the values were 91, 13, and 85 nm by the Williamson-Hall model. FTIR confirmed the presence of W-O-W, O-W-O, Ag-I, and O-Ag-O bonds in the coupled material. DRS results showed absorption edge wavelengths of 451, 462, and 495 nm (corresponding to the band gap values of 2.75, 2.68, and 2.51 eV) for Ag₂WO₄, AgI, and AgI/Ag₂WO₄ catalyst, respectively. Synergistic photocatalytic activity of the coupled system was achieved towards ceftriaxone (CTX) in an aqueous solution (about 33% 10 ppm CTX solution was degraded without any optimization in the initial conditions of catal dose 0.3 g/L (Ag₂WO₄:AgI with mole ratio 1:2 and 30 min abrasion time), and irrad. time 45 min, C_CTX). This boosted effect depended on the AgI:Ag₂WO₄ mole ratio and grinding time for the mechanical preparation of the binary catalyst (optimums: mole ratio of 4:1 and time 30 min). The photodegradation kinetics obeyed the Hinshelwood model with the apparent first-order rate constant (k) of 0.013 min^-1 (t_1/2 = 53.30 min). Performing the COD on the photodegraded CTX solutions got a Hinshelwood plot with a slope of 0.019 min^-1 (t_1/2 = 36.5 min).

Ag-Modified ZnO for Degradation of Oxytetracycline Antibiotic and Reactive Red Azo Dye

It is known that low electron-hole separation efficiency is the major disadvantage influencing low photoactivity of the UV-active ZnO photocatalyst. To solve this drawback, the excellent fabrication technique has been used to disperse silver metal on ZnO surface. In this study, an addition of silver content up to 15 wt% was carried out. The 5Ag-ZnO sample, comprising 5 wt% of silver metal, displayed a hexagonal wurtzite structure, and a band gap of 3.00 eV, with high sunlight-active photocatalytic performance of 99-100% and low photo-corrosion problem. The complete degradation of oxytetracycline (OTC) antibiotic and reactive red dye 141 (RR141) dye under natural sunlight was achieved. The highest rate constant of 0.061 min-1 was detected. The enhancement of the performance is mainly due to lowering of the electron-hole recombination rate. Dispersion of silver on ZnO causes the generation of the Schottky barrier at the interface between Ag and ZnO, so that improvement of quantum efficiency and enhancement of the resultant photoactivity could be expected. Furthermore, good distribution of metallic silver also causes a red shift in absorption of light toward the visible spectrum. This is strongly attributed to the surface plasmon resonance effect, which occurred after successful decoration of the noble metal on ZnO. The photocatalyst, with great structural stability, still maintains high photocatalytic efficiency even after five times of use, implying its excellent cycling ability. The present finding offers a new road to generate a silver decorated ZnO photocatalyst for the complete removal of dye and antibiotics contaminated in the environment.

Valorization of Waste Tungsten Filament into mpg-C3N4-WO3 Photocatalyst: A Sustainable e-Waste Management and Wastewater Treatment

The waste of tungsten filament materials in the environment is one of the reasons for environmental pollution, and it is very dangerous to animals and plants. To date, not much attention has been given to its utility or recyclability. Herein, the present work reported the synthesis of tungsten trioxide nanoparticles (WO₃ NPs) by the utilization of cost-free waste tungsten filament by a simple calcination method. A mesoporous graphitic carbon nitride-tungsten trioxide (mpg-C₃N₄-WO₃) composite designed from the WO₃ NPs produced from tungsten filament waste and thiourea as a carbon and nitrogen precursor by a one-step calcination method. The synthesized samples were characterized and confirmed by different characterization techniques. The photocatalytic behavior of the synthesized mpg-C₃N₄-WO₃ composite was assessed, with respect to the effect of initial pH, amount of photocatalyst, dye concentration, and reaction time, as well for the degradation of Methylene Blue (MB) dye under sunlight. The best photocatalytic performance (92%) was achieved using mpg-C₃N₄-WO₃ with experimental condition ([photocatalyst] = 100 mg/L, [MB]₀ = 10 mg/L, pH 8, and time = 120 min) under sunlight irradiation with excellent photostability than that of isolated mpg-C₃N₄ and WO₃ NPs. The histotoxicological studies also showed that the photodegraded products of MB were found to be nontoxic and did not structurally changes in the gill architecture as well as brain tissues of freshwater fish Labeo rohita.

NiFe2O4/g-C3N4 heterostructure with an enhanced ability for photocatalytic degradation of tetracycline hydrochloride and antibacterial performance

In this work, NiFe₂O₄/g-C₃N₄ heterostructure was prepared and used for the photocatalytic decomposition of tetracycline hydrochloride antibiotic and for inactivation of E. coli bacteria. The fabricated NiFe₂O₄/g-C₃N₄ composite displayed enhanced ability for photodegradation of organic pollutants and disinfection activities compared to the bare samples, because of the enhancement of visible light absorbance, heterojunction formation and photo-Fenton process. The optimized sample 10%-NiFe₂O₄/g-C₃N₄ has photodegraded 94.5% of tetracycline hydrochloride in 80 min. The active species trapping experiments revels that ·O₂^-, h⁺ and •OH are key decomposing species participated in the antibiotic degradation. It is hoped that the present study will provide a better understanding to fabricate efficient photocatalysts for the decomposition of organic pollutants and disinfection of bacteria.

A Z-scheme CdS/BiVO4 photocatalysis towards Eriochrome black T: An experimental design and mechanism study

The synergistic photocatalytic activity was obtained when CdS and BiVO₄ nanoparticles (NPs) were coupled. The samples were characterized by XRD, FTIR, SEM-EDX, and UV-DRS techniques, and their pHpzc was also estimated. The crystallite size of the coupled sample was estimated at 37.3 and 12.5 nm by the Scherrer and Williamson-Hall equations, respectively. The band gaps and the potential positions of VB and CB levels of the semiconductors used were determined. The highest boosted photocatalytic activity was obtained when the CdS: BiVO₄ mole ratio was 1:1. RSM studied the simultaneous interactions between the selected variables, and the model F-value of 110.61> F_{0.05, 14, 13} = 2.4 accompanied by the LOF F-value of 5.20 < F_{0.05, 10, 3} = 8.79 confirm the model significance. The correlation coefficients of R² = 0.9861, the adjusted R² = 0.9710, and the predicted R² = 0.9417, also establish a satisfactory model for processing the experimental data. In the scavenging agent study, photodegradation mechanisms were suggested; among them, the direct Z-scheme mechanism is more favorable for illustrating the EBT-photodegradation by the binary CdS-BiVO₄ photocatalyst. The proposed system, especially the direct Z-scheme mechanism, is suitable as a potential hydrogen production system.

Effective adsorption of crystal violet onto aromatic polyimides: Kinetics and isotherm studies

The motive of this work is to synthesis aromatic polyimides by a two-step poly condensation process and the prepared aromatic polyamides (APIs) is been used as an effective functionalized adsorbent for the removal of carcinogenic crystal violet (CV) from aqueous medium. The adsorption efficiency of the APIs was enhanced by incorporation different functional moieties (varying aromatic dianhydrides with -O-, -(CF₃)₂-, -(CH₃)₂-) in the polymer structure. The initial and final concentration of CV was measured using UV-Vis spectrometer. The adsorption process was optimized by varying the parameters such as the effect of solution pH, contact time, initial dye concentration, and adsorbent dosage. Kinetics and isotherms of the adsorption system were appraised using data obtained from effect of contact time and initial dye concentration with corresponding empirical modelling techniques respectively. The evaluated results of the adsorption kinetic studies confirmed that the adsorption of API onto CV is followed a pseudo-second-order kinetic model. The adsorption behaviour and their interactions between APIs and CV are well established. The experimental results of this research output could be confirmed that APIs is a very effective adsorbent for the removal of cationic dye from aqueous.

Nanomaterials photocatalytic activities for waste water treatment: a review

Water is necessary for the survival of life on Earth. A wide range of pollutants has contaminated water resources in the last few decades. The presence of contaminants incredibly different dyes in waste, potable, and surface water is hazardous to environmental and human health. Different types of dyes are the principal contaminants in water that need sudden attention because of their widespread domestic and industrial use. The toxic effects of these dyes and their ability to resist traditional water treatment procedures have inspired the researcher to develop an eco-friendly method that could effectively and efficiently degrade these toxic contaminants. Here, in this review, we explored the effective and economical methods of metal-based nanomaterials photocatalytic degradation for successfully removing dyes from wastewater. This study provides a tool for protecting the environment and human health. In addition, the insights into the transformation of solar energy for photocatalytic reduction of toxic metal ions and photocatalytic degradation of dyes contaminated wastewater will open a gate for water treatment research. The mechanism of photocatalytic degradation and the parameters that affect the photocatalytic activities of various photocatalysts have also been reported.

Enhanced photocatalytic degradation of malachite green dye by highly stable visible-light-responsive Fe-based tri-composite photocatalysts

A novel visible-light-sensitive ZnVFeO₄ photocatalyst has been fabricated by the precipitation method at different pH values for the enhanced photocatalytic degradation of malachite green (MG) dye as a representative pollutant under visible light irradiation at neutral pH conditions. The structure and optical characteristics of the prepared photocatalysts were investigated by XRD, FTIR, N2 adsorption-desorption, TEM, diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) analyses. In addition, the photocatalytic activity of ZnVFeO₄ photocatalysts superior the efficiency to be more than that of the mono and bi-metal oxides of iron and iron zinc oxides, respectively. The best sample, ZnVFeO₄ at pH 3, significantly enhances the degradation rate under visible light to be 12.7 × 10^-3 min^-1 and can retain a stable photodegradation efficiency of 90.1% after five cycles. The effect of the catalyst dose and the initial dye concentration on the photodegradation process were studied. This promising behavior under visible light may be attributed to the low bandgap and the decreased electron-hole recombination rate of the ZnVFeO₄ heterostructures. The scavenger experiment confirmed that the hydroxyl radicals induced the MG photodegradation process effectively. Hence, the ZnVFeO₄ is a reliable visible-light-responsive heterostructure photocatalyst with excellent potential for the photodegradation of organic pollutants in wastewater treatment.

Se substituted 2D-gC3N4 modified disposable screen-printed carbon electrode substrate: A bifunctional nano-catalyst for electrochemical and absorption study of hazardous fungicide

The indispensable usage of pesticides for the control and prevention of pests is probable and includes several types based on the problems in the crops. Among them, fungicides, are one problem-solving agent curing fungal developments. the disproportionate use of fungicides will lead to environmental deterioration and several health issues. The assessment of such fungicides is highly motivated to be detected. Under the class of two-dimensional materials, graphitic carbon nitride (GCN) with high surface area and high electrocatalytic activity was chosen as electrode material. The efficiency of GCN was improved with the subsequent substitution of selenium (Se) into the triazine ring as Se-GCN. The structural and surface analysis was done and the layered structure was proved. The electrochemical detection of CBM showed a lower detection limit at 6 nM with a linear range 0.099 μM-346.9 μM while, the absorption studies showed a LOD of 20 nM with a linear range of 0.099 μM-182.09 μM. The orange juice and vegetable extract samples had good recovery with CBM at Se-GCN modified disposable screen-printed electrode. The developed disposable electrode was more sensitive with 6.45 μAμM^-1cm² sensitivity and highly reactive with CBM. Moreover, the developed sensor will be more effective in sensing applications to avoid the menace generated by several agents.

Oxalate regulate the redox cycle of iron in heterogeneous UV-Fenton system with Fe3O4 nanoparticles as catalyst: Critical role of homogeneous reaction

The redox cycle of iron is a well-known rate-determining step for hydroxyl radical generation in photo-Fenton system. In this study, oxalate was employed as regulator to enhance the degradation of Orange II in Fe₃O₄ magnetic nanoparticles (NPs)-catalyzed heterogeneous UV-Fenton system. Results showed that the oxalate could interact with the surface ≡Fe^III species of catalyst, which weakened the bond of ≡Fe^III-O and promoted the leaching of iron ions. Then the redox cycle of iron and generation of HO· would be accelerated via the homogeneous UV-Fenton reaction. The degradation rate constant of Orange II reached 0.220 min^-1 when additional oxalate concentration was 0.4 mM, which was 2.5 times as high as that without oxalate in heterogeneous UV-Fenton system. In this case, the removal efficiencies of color and TOC were 99.3% and 92.0% after 30 and 120 min treatment, respectively. In addition, based on the results of XRD and XPS characterization, it could be deduced that the crystal structure and elemental configuration of Fe₃O₄ magnetic nanoparticles could be maintained after reaction. Besides, the results of FTIR and magnetization characterization indicated that the C₂O₄^2- on surface of catalyst could be degraded and the catalyst could be easily separated from aqueous by applying an external magnetic field. The Fe₃O₄ magnetic nanoparticles showed high catalytic stability and reusability under the regulation of oxalate due to the fact that the leached iron ions could be re-adsorbed on the catalyst after treatment.

Photocatalytic Degradation of Polyethylene Microplastics and Disinfection of E. coli in Water over Fe- and Ag-Modified TiO2 Nanotubes

In this study, Fe- and Ag-modified TiO2 nanotubes were synthesized via an anodization method as photocatalysts for degradation of polyethylene microplastics and disinfection of Escherichia coli (E. coli). The anodization voltage, as well as the Fe3+ or Ag+ concentrations on TiO2 nanotubes were evaluated and correlated to their corresponding photocatalytic properties. TiO2 nanotubes were firstly synthesized by anodization of Ti plates in a glycerol-based electrolyte, followed by incorporation of either Fe or Ag via a Successive Ionic Layer Adsorption and Reaction (SILAR) method with Fe(NO3)3 and AgNO3 as Fe and Ag precursors, respectively. UV-Vis DRS shows that the addition of Fe or Ag on TiO2 nanotubes causes a redshift in the absorption spectra. The X-ray diffractograms indicate that, in the case of Fe-modified samples, Fe3+ was successfully incorporated into TiO2 lattice, while Ag scatters around the surface of the tubes as Ag and Ag2O nanoparticles. A microplastic degradation test was carried out for 90 mins inside a photoreactor with UVC illumination. TiO2 nanotubes that are anodized with a voltage of 30 V exhibit the best degradation results with 17.33% microplastic weight loss in 90 mins. Among the modified TiO2 nanotubes, 0.03 M Ag-TiO2 was the only one that surpassed the unmodified TiO2 in terms of microplastic degradation in the water, offering up to 18% microplastic weight loss in 90 min. In terms of E. coli disinfection, 0.03M Ag-TiO2 exhibit better performance than its unmodified counterpart, revealing 99.999% bactericidal activities in 10 mins. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

The boosted activity of AgI/BiOI nanocatalyst: a RSM study towards Eriochrome Black T photodegradation

Nowadays, critical environmental pollution needs some novel, simple, effective, and cost-effective catalysts with high efficiency in the visible region of the light. Thus, the AgI/BiOI coupled nanocatalyst sample (CS) was prepared and briefly characterized. The pH_pzc values of 6.2, 5.4, and 4.5 were estimated for AgI, BiOI, and AgI/BiOI samples. Based on the PXRD results, average crystallite sizes of 35.2, 34.7, and 34.1 nm were obtained for AgI, BiOI, and AgI/BiOI samples from the Scherrer formula and 38.3, 25.6, and 25.6 nm by the Williamson-Hall formula. SEM image confirmed a sheet-like BiOI morphology covered by AgI nanoparticles. The simultaneous interactions of the influencing variables on the boosted photocatalytic activity of CS sample towards Eriochrome Black T (EBT) were evaluated by response surface methodology (RSM) (under 100-W tungsten lamp irradiation with 230 mW/m².nm irradiance). The goodness of the model was confirmed by the significance of the model (F value of 65.68 > F_{0.05, 14, 13} = 2.55) and a non-significant LOF (F value of 0.97 < F_{0.05, 10, 3} = 8.79) at a 95% confidence interval obtained in ANOVA analysis of the results. The center point runs have the following conditions: catalyst dose: 0.68 g/L; pH: 7.5; C_EBT: 7.25 mg/L; and irradiation time: 53.5 min, while the optimal run included the following conditions: catalyst dose: 1.0 g/L; pH: 4; C_EBT: 10 mg/L; and irradiation time: 80 min. About 95% of EBT molecules were degraded in the optimal conditions.

Adsorptive and photocatalytic remediation of hazardous organic chemical pollutants in aqueous medium: A review

The provision of clean water is still a major challenge in developing parts of the world, as emphasized by the United Nation Sustainable Development Goals (SDG 6), and has remained a subject of extensive research globally. Advancements in science and industry have resulted in a massive surge in the amount of industrial chemicals produced within the last few decades. Persistent and emerging organic pollutants are detected in aquatic environments, and conventional wastewater treatment plants have ineffectively handled these trace, bioaccumulative and toxic compounds. Therefore, we have conducted an extensive bibliometric analysis of different materials utilized to combat organic pollutants via adsorption and photocatalysis. The classes of pollutants, material synthesis, mechanisms of interaction, merits, and challenges were comprehensively discussed. The paper highlights the advantages of various materials used in the removal of hazardous pollutants from wastewater with activated carbon having the highest adsorption capacity. Dyes, pharmaceuticals, endocrine-disrupting chemicals, pesticides and other recalcitrant organic pollutants have been successfully removed at high degradation efficiencies through the photocatalytic process. The photocatalytic degradation and adsorption processes were compared by considering factors such as cost, efficiency, ease of application and reusability. This review will be good resource material for water treatment professionals/scientists, who may be interested in adsorptive and photocatalytic remediation of organic chemicals pollutants.

Recent progress on ultrasound-assisted electrochemical processes: A review on mechanism, reactor strategies, and applications for wastewater treatment

The electrochemical advanced oxidation processes (EAOPs) have received significant attention among the many other water and wastewater treatment technologies. However, achieving a desirable removal effect with a single technique is frequently difficult. Therefore, the integration of ultrasound technique with other processes such as electrocoagulation, electro-Fenton, and electrooxidation is a critical way to achieve effective organic pollutants decomposition from wastewater. This review paper is focused on ultrasound-assisted electrochemical (US/electrochemical) processes, so-called sonoelectrochemical processes of various organic pollutants. Emphasis was given to recently published articles for discussing the results and trends in this research area. The use of ultrasound and integration with electrochemical processes has a synergistic impact owing to the physical and chemical consequences of cavitation, resulting in enhancing the mineralization of organic pollutants. Various types of sonoelectrochemical reactors (batch and continuous) employed in the US/electrochemical processes were reviewed. In addition, the strategies to avoid passivation, enhanced generation of reactive oxygen species, and mixing effect are reviewed. Finally, concluding remarks and future perspectives on this research topic are also explored and recommended.