Maximum Degradation Efficiency Research Articles

Saraca asoca-assisted green synthesise of ZnO nanoplatelets for photocatalytic activity and adsorption kinetics

ABSTRACT ZnO nanoplatelets (ZnO NPLs) have been successfully synthesised using microwave-assisted technique (400 W, 180 sec) with the plant extract Saraca-asoca. The surface morphology analysis confirms ZnO’s plate-like nanostructure, leading to the creation of ZnO NPLs. The results show excellent photocatalytic performance (at 125 W for both UV and visible light) and effectiveness against malachite green (MG), methyl orange (MO) and rhodamine B (RhB). Notably, ZnO NPLs break down malachite green (MG) exceptionally well, reaching a maximum degradation efficiency of 92% in under 30 min (UV light). Moreover, ZnO NPLs have been evaluated for MG adsorption characterised by the pseudo-first-order kinetic model, alongside the Freundlich and Langmuir isotherm models. In the Freundlich model, the maximal adsorption capacity is determined to be 331 mg/g. These new faceted ZnO NPLs have a great potential for use in photocatalytic and adsorption processes that aim to reduce aqueous pollutants.

Enhanced photocatalytic removal of methyl orange dye employing SiO2/Mn2O3 based nanocatalyst under visible light

Surface water contamination by dye pollutants is a global environmental concern. The treatment of effluent from textile waste using metal oxide-based photocatalysts is a widely employed approach owing to its efficacy and simplicity. Herein, the synthesis and fabrication of novel visible radiation receptive manganese oxide and mesoporous silica nanocomposites (Mn2O3/SiO2) is described. Surface morphology of nanocomposites using scanning electron microscopy (SEM) displayed spherical shaped agglomerated structure. The chemical composition of nanocomposites was examined by using energy dispersive x-ray (EDX) analysis respectively indicating the presence of respective elements. Structural analysis was carried out by using XRD spectroscopy, while optical properties were evaluated by employing UV–visible spectroscopy. The photocatalytic activity of pure Mn2O3 and SiO2 nanoparticles as well as their nanocomposites with two different ratios Mn2O3/SiO2 (1:3) and Mn2O3/SiO2 (3:1) were evaluated by using methyl orange (MO) as a model dye. The band gap energy of Mn2O3/SiO2 (1:3) and Mn2O3/SiO2 (3:1) nanocomposite was 2.39 eV and 1.69 eV respectively. The nanocomposites exhibited improved photocatalytic efficiency as compared to pure nanoparticles as a function of pH and mixing ratio. For instance, at pH 7.0, Mn2O3/SiO2 (1:3) nanocomposite has depicted maximum degradation efficiency of 68 % for degradation of MO as compared to Mn3O4/SiO2 (3:1) nanocomposite, Mn3O4 and SiO2 nanoparticles. However, at pH 2.0 Mn2O3/SiO2 (3:1) nanocomposite had shown maximum degradation efficiency of 99 % as compared to Mn2O3/SiO2 (1:3), Mn2O3 and SiO2 nanoparticles. The degradation reaction followed pseudo first order kinetics. At pH 7.0, the rate constant values of nanocomposites i.e. Mn2O3/SiO2(1:3) and Mn2O3/SiO2(3:1) comes out to be 4.68 × 10−3 min−1 and 2.49 × 10−3 min−1 respectively. At pH 2.0, the rate constant values calculated for Mn2O3/SiO2(1:3) nanocomposite and Mn2O3/SiO2(3:1) nanocomposite was 4.91 × 10−3 min−1 and 1.24 × 10−2 min−1 respectively. The easy fabrication of these nanocomposites coupled with facile tuning of their properties make them suitable contenders for efficient dye degradation in wastewater treatment.

Competent CuS QDs@Fe MIL101 heterojunction for Sunlight-driven degradation of pharmaceutical contaminants from wastewater

In this study, we introduce an advanced photocatalyst developed by integrating copper sulfide quantum dots (CuS QDs) with an iron-based metal–organic framework (MOF), specifically Fe MIL101. The resulting CuS QDs@Fe MIL101 photocatalyst is engineered to efficiently degrade meloxicam (MLX) under simulated sunlight. The heterojunctions were generated by incorporating different concentrations of CuS QDs (5 %, 10 %, 15 %, 20 %, and 50 %) into the Fe MIL101 MOF matrix using the microwave-assisted hydrothermal method. The results of the XRD and the TEM studies confirmed the formation of the heterojunctions, which maintain the structural integrity of both CuS QDs and Fe MIL101. The BET measurements indicated a decrease in surface area upon CuS QDs incorporation, attributed to porés blockage and structural modifications. UV–Vis diffuse reflectance spectroscopy (DRS) revealed a redshift in absorption edges as CuS QDs content increased, enhancing visible light absorption. Photoluminescence (PL) investigations revealed that the 15 % CuS QDs@Fe MIL101 heterojunction had an effective charge separation and low recombination rates. The zeta potential analysis revealed a negative surface charge, indicating an overall electronegative characteristic. The photocatalytic performance, assessed through the degradation of MLX, demonstrated that the 15 % CuS QDs@Fe MIL101 heterojunction achieved the maximum degradation efficiency, reaching 96 % after 45 min of irradiation at a dosage of 0.1 g/L. This exceptional performance is attributed to potent charge separation, improving visible light absorption, high surface area and adsorption capacity. Various scavengers were used to investigate the roles of different reactive species, revealing holes as the predominant active species in the photocatalytic degradation process. These results highlight the potential of 15 % CuS QDs@Fe MIL101 heterojunctions as efficient photocatalyst for environmental remediation from pharmaceutical pollutants under simulated sunlight. These findings highlight the potential for application of CuS QDs@Fe MIL101 in real-world wastewater treatment systems, particularly in addressing pharmaceutical contaminants like meloxicam in industrial effluents.

Photocatalytic Degradation of Acetaminophen Using Carbon-TiO2 Nanocatalyst Extracted from Hibiscus Flower under Visible Light

In today’s world pharmaceutical waste in the Environment has become a worldwide issue. These compounds are used in living beings to cure diseases and prevent them. But the disposal of these types of waste was not disposed of properly. In this study, the pharmaceutical compound – “Acetaminophen” (ACT) was degraded using photocatalytic degradation which is one among the pharmaceutical waste. The Compound is much harmful to living beings and causes severe disorders like vomiting and nausea. In this paper, the Acetaminophen is degraded using the carbon-TiO2 nanocatalyst. The Carbon-TiO2 nanocatalyst was synthesized and characterized such as particle size, zeta potential, FTIR, Surface area analyzer, EDX, and SEM images. The Acetaminophen was degraded by using Photocatalytic degradation under transparent condition. The analysis of disintegration was performed by using the UV-vis spectrophotometer. The results obtained indicated the maximum degradation efficiency of around 87% obtained. Hence, C-TiO2 can be utilized under visible light to effectively degrade Acetaminophen.

Dye degradation and antimicrobial efficacy of cesium-doped Y2O3 nanostructures: in silico docking study.

Developing multifunctional nanomaterials is crucial to rising global concerns over environmental contamination caused by dye effluents and antibiotic resistance. This work presents cesium (Cs)-doped Y2O3 nanostructures (NSs) as viable options for catalytic dye degradation and antibacterial action. This study prepared yttrium oxide (Y2O3) and various (2, 4, and 6 wt%) concentrations of Cs-doped Y2O3 NSs via co-precipitation technique. The pure and Cs-doped Y2O3 NSs were used to degrade methylene blue (MB) at different pH levels and assess the antibacterial properties against multidrug-resistant (MDR) Escherichia coli (E. coli). The X-ray diffraction spectra of the pure and Cs-doped Y2O3 revealed the presence of cubic and monoclinic structures. The UV-vis absorption spectra displayed distinct peaks at 274 nm and a reduction in band gap energy (from 4.94 eV to 4.41 eV) upon incorporation of Cs. Maximum degradation efficiency of up to 99% attributed to 6% Cs-doped Y2O3. The bactericidal activity against MDR E. coli exhibited 4.15 mm inhibition zones at higher concentrations of Cs-doped Y2O3. The bactericidal mechanism of Cs-Y2O3 NSs was further investigated by molecular docking studies for β-lactamase and DNA gyrase enzymes.

Captivating 2H-MoS2 nanoflowers for efficient NH3 detection and photocatalytic dye degradation

This research unveils the gas sensing and photocatalytic potential of 2H-MoS2 nanoflowers, offering a promising solution for ammonia sensing and wastewater remediation. The 2H phase of MoS2 nanoflowers is synthesized via a simple one-step hydrothermal method using ammonium heptamolybdate and thiourea. The elemental and morphological study confirms the formation of the 2H phase of MoS2 nanoflowers with an average sheet thickness of 14 nm. The XRD and HR-TEM analysis findings are in good accordance with the interlayer spacing of MoS2, calculated to be 0.64 nm. The 2H-MoS2 nanomaterial based chemiresistive sensor is tested for six different targets (NH3, C2H5OH, C3H6O, C3H7OH, HCHO, and C6H5CH3) and shows good selectivity towards ammonia (NH3) with the highest response of 81 %. The response-recovery time, repeatability, concentration, and humidity-based analysis are conducted for the analysis of the sensor. The fabricated 2H-MoS2 based sensor shows a response time of 8.5 s and a recovery time of 4.3 s. Furthermore, three model water contaminated dyes, MB, MO, and RB, are chosen for the photocatalytic experiment under visible light irradiation. The reusability, relative degradation, and pseudo-first-order analysis are used to evaluate the photocatalytic dye degradation properties of 2H-MoS2 nanoflowers. The reaction rate constant of 2H-MoS2 nanomaterials for MB, MO, and RB dyes is calculated to be (0.05010) min−1, (0.03458) min−1, and (0.02516) min−1, respectively. The maximum degradation efficiency of 2H-MoS2 nanoflowers towards MB, MO, and RB dye is 95 %, 86 %, and 76 %, respectively, under visible light irradiation. These findings suggest that the hydrothermally synthesized 2H-MoS2 nanoflowers have multifunctional applications such as effective NH3 sensors as well as photocatalysts for organic dye degradation, paving the way for more efficient and sustainable gas sensing and wastewater treatment technologies.

Ingenious development of bandgap engineered MIL-101(Fe) core-shell supported on SnO2/ZnO heterojunction and its photocatalytic activity towards azo dye degradation: Process optimization and mechanistic insight

Water pollution is a pressing global concern, exacerbated by industrial effluents containing hazardous azo-dyes such as Trypan blue (TB) and Methyl orange (MO), which contaminate water bodies and threaten ecosystems. The scarcity of pure water intensifies the urgency to develop effective remediation strategies to tackle the toxic dye pollutants. In the present work, an attempt has been made to fabricate and utilize a novel ternary MOF-based SnO2/ZnO@MIL-101(Fe) photocatalyst for the removal of TB and MO dyes from an aqueous medium. The photocatalyst was characterized using various analytical techniques, like XRD, FTIR, UV–vis DRS, PL, SEM, TEM, and XPS, which provide insights into the composites’ crystal structure, morphology, and optical properties, which are crucial for understanding their photocatalytic behavior. The photocatalytic performance of the heterojunction was investigated under various reaction parameters such as catalyst dosage, initial concentration of dyes, and light irradiation time. The results demonstrated the superior performance of the SnO2/ZnO@MIL-101(Fe) composites in degrading the mono-azo and di-azo dyes under visible light irradiation via a photo-fenton process. The maximum degradation efficiency of 97.44 % and 98.8 % were obtained for TB and MO within 30 and 55 min, respectively. Furthermore, the change in the total organic carbon (TOC) was monitored to verify the degree of mineralization of the azo dyes. The extremely high dye degradation activity and TOC removal can be attributed to the formation of a suitable heterojunction interface between the components of the photocatalyst, leading to effective charge carrier transport and the generation of active radicals. Finally, based on the radical scavenging experiments, ESR, and VB-XPS analysis, a plausible mechanism for the photodegradation process was derived. This research contributes to the advancement of sustainable water treatment technologies by providing insights into the design, fabrication, and utilization of novel composites for efficient remediation of dye-contaminated wastewater.

Green synthesis of Silver-iron-zinc oxides nanocomposite via Embelia schimperia leaf extract for photo-degradation of antibiotic drug from pharmaceutical wastewater

The co-precipitation approach is used in the current study to create an environmentally friendly Ag/Fe/ZnO nanocomposites utilizing an aqueous leaf extract of Embelia schimperia. The synthesized nanocomposite was characterized using Fourier-transform infrared, UV, X-ray, UV–vis, DLS, TGA, and SEM to determine its functional group, structure, bandgap energy, size distribution, a mass of loss, and energy gain or loss, and morphological structure, respectively. The bioactive components of Embelia schimperia, synthesized Ag/Fe/ZnO NCs and degradation of Amoxicillin via photocatalyst were assessed. The response surface methodology of central composite design (CCD) was used to examine and optimize the effects of three independent variables on the degradation of Amoxicillin under visible light. According to the experimental findings, the maximum photocatalytic degradation efficiency was achieved at green synthesized Ag/Fe/ZnO NCs dosage of 100 mg, a concentration of Amoxicillin of 30 mg/L and a radiation time of 180 min. Their findings show that Embelia schimperia extract-derived Ag/Fe/ZnO nanocomposites is a promising alternative for degradation of pharmaceuticals contamination of wastewater via photocatalytic under the given conditions.

Hybridized Co, Mn co-doped ZnO@graphite for photocatalytic degradation of orange G dye: Ecotoxicity and phytotoxicity evaluation

This study proposes a novel research investigation into the remediation of orange G dye (acid orange 10) contaminated solution using Co, Mn co-doped ZnO@graphite composite (MC-ZnO/G) material synthesized by a simple hydrothermal route. XRD, FT-IR, EDX, FE-SEM, TEM, BET analysis, UV-Vis DRS spectroscopy and XPS techniques were employed to analyse the physic-chemical characteristics of MC-ZnO/G nanocomposite. MC-ZnO/G shows a higher surface area of 27.4 m2/g than pristine ZnO (12.26 m2/g). Under optimal condition (concentration - 45 ppm, photocatalyst 20 mg and pH - 7), MC-ZnO/G photocatalyst attained a maximum degradation efficiency (MDE) of 97.8 % during 150 min of visible light exposure, whereas pristine ZnO shows a maximum degradation efficiency of 53.5 % only. Furthermore, MC-ZnO/G nanocomposite demonstrated strong stability and reusability, retaining 95.9 % of its stability even after 4 consecutive cycles. The radical studies have been carried out the scavengers, viz., IPA, BQN and EDTA. Under optimal levels, the elimination of OG dye is primarily due to the presence of •OH radicals. The treated effluent was evaluated for its effects on aquatic life, specifically Danio rerio (Zebra fish) by a survival rate of 2 days, and plants, namely Trigonella foenum-graecum (Fenugreek) by a survival rate of 7 days, in order to assess its toxicity.

Rational design of S‒scheme Cd0.5Zn0.5S/CeO2 heterojunction for enhanced photooxidation of antibiotics and photoreduction of Cr(VI)

Current photocatalysts endowed with oxidation and reduction capabilities for pharmaceuticals and heavy metals removal face numerous challenges, such as a lack of sufficient reactive sites, poor electron-hole separation, and limited oxidation and reduction capabilities. In this study, we aimed to overcome these limitations by employing a simple solvothermal method to fabricate a novel S-scheme heterojunction, Cd0.5Zn0.5S/CeO2. The optimal Cd₀.₅Zn₀.₅S/CeO2 heterojunction achieved a maximum ciprofloxacin degradation efficiency of 86 % within 30 min, showing a remarkable improvement of 2.4 and 4.6 times compared to pristine Cd₀.₅Zn₀.₅S and CeO2, respectively. The heterojunction also demonstrated a remarkable 100 % photoreduction efficiency of Cr(VI) within 30 min, which is double the photodegradation performance of the individual materials. The combination of Cd₀.₅Zn₀.₅S with CeO2 to form the Cd₀.₅Zn₀.₅S/CeO2 S-scheme heterojunction effectively enhanced spatial photo-carrier separation and optimized the photo-redox capability, resulting in a substantial improvement in photocatalytic performance and stability. Through radical trapping experiments, the primary reactive species responsible for CIP degradation were identified as h⁺, OH•, and •O₂⁻. Additionally, e⁻ was determined to be the key species responsible for the photoreduction of Cr(VI). Based on these findings, we proposed a plausible photocatalytic reaction pathway for the simultaneous elimination of both CIP and Cr(VI). This study underscores the significant potential of the Cd0.5Zn0.5S/CeO2 S-scheme heterojunction for advanced wastewater treatment applications, highlighting its innovative approach and superior performance.

Ultrasonic assisted synthesis of nanoporous carbon/CeVO4 nanocomposite for supercapacitor and photocatalytic applications

Here, nanoporous carbon (NPC)/CeVO4 nanocomposite synthesized via ultrasonic assisted method for supercapacitor and tartrazine dye degradation application. Transmission electron microscope (TEM) studies confirmed the CeVO4 nanoparticles well embedded on the NPC surface in the NPC/CeVO4 nanocomposite. Spherical shaped CeVO4 nanoparticles are well incorporated on the surface of NPC therefore NPC/CeVO4 nanocomposite which possess a porous-like structure would improve the supercapacitor applications and dye degradation performance. As expected, the specific capacitance (Cs) values (555 F g−1) of NPC/CeVO4 nanocomposite showed enhanced performance as compared to CeVO4 nanoparticles (234 F g−1) at a current density of 1 A g−1 and the capacitance retention of the designed electrode as 95 % after 5000 cycles. The photodegradation of tartrazine dye using pure CeVO4 nanoparticles and NPC/CeVO4 nanocomposite was explored under visible light irradiation. The photocatalytic degradation experiment demonstrated that the NPC/CeVO4 exhibits the maximum degradation efficiency (98.76 %) of the tartrazine with was reached within 120 min. Moreover, the rate constant of NPC/CeVO4 for tartrazine dyes decomposition was 0.0192 min−1 representing that it is two-fold higher than pure CeVO4 (0.0073 min−1). The superior electrochemical and photocatalytic properties of NPC/CeVO4 nanocomposite have been observed due to the well-designed structure and high surface area. Consequently, as-prepared NPC/CeVO4 material could be a promising material for electrochemical supercapacitor and dye degradation of the tartrazine organic pollutant.

Optimizing photocatalytic performance with Ag-doped ZnO nanoparticles: Synthesis and characterization

The development of nanotechnology has significantly impacted the improvement of photocatalytic performance of ZnO NPs. In this study synthesis of pure ZnO and Ag–ZnO nanoparticles via a co-precipitation method at varying Ag concentrations (1 %, 2 %, 3 %, 4 % and 6 %) to enhance their photo catalytic efficacy. X-ray diffraction (XRD) analysis estimates crystallite size which decreased by increasing Ag concentration, ranging from 30.6 nm (Pure ZnO) to 22.5 nm 6 % Ag-doped ZnO. Scanning electron microscopy (SEM) revealed decrease in particle size with increasing Ag content. UV–Vis spectroscopy indicating a narrowed band gap of optimal sample. Photocatalytic activity of the synthesized nanoparticles was evaluated using methylene orange (MO) dye degradation under light irradiation. The MO concentration exhibited a decrease with increasing irradiation time in the presence of photocatalysts. Recombination rate of NPs decreases by increasing the concentration of Ag i.e. 4%Ag dope ZnO NPs have lowest recombination rate and maximum degradation efficiency. FTIR analysis confirms the preparation of Ag-doped ZnO NPs. This improvement can be credited to the synergistic effect of Ag doping, leading to a narrowed band gap and potentially maximum degradation of MO by using Ag-doped ZnO NPs.

Green synthesis of Bi2O3, MnO2 and their nanocomposite (Bi2O3/MnO2) for efficient photodegradation and antimicrobial activity

An eco-friendly green synthesis approach was used to synthesize Bi2O3, MnO2, and Bi2O3/MnO2 nanocomposite in order to comprehend the effect of nanocomposite on the photocatalytic and antibacterial activity. The structural parameters of as prepared samples were confirmed using X-ray diffraction analysis (XRD). Scherrer formula was applied to find out crystallite size, which ranged from 8 nm to 13 nm. XRD confirmed the geometrical structure of Bi2O3, MnO2 and Bi2O3/MnO2 nanocomposite showing monoclinic structure. The FTIR peaks also confirm the successful synthesis of Bi2O3/MnO2 nanocomposite. SEM of Bi2O3/MnO2 nanocomposite revealed that nanoparticles of Bi2O3 are developed on MnO2 granules. In UV–Vis spectroscopy, absorption maxima showed in the range of 200 nm to 400 nm and band gap ranging from 2.4 eV to 3.4 eV. The antibacterial activity of Bi2O3, MnO2, and Bi2O3/MnO2 nanocomposite was investigated against two gram negative-bacteria (Pseudomonas and Escherichia coli) at 10 mg and 20 mg concentration using disk diffusion method. The zone of inhibitions against Escherichia coli at 10 mg and 20mgl were 22 mm and 26 mm while against Pseudomonas were 28 mm and 33 mm for Bi2O3/MnO2 nanocomposite. Bi2O3/MnO2 composite shows better result as compared to Bi2O3 and MnO2. Photocatalytic activity was carried out using Bi2O3, MnO2, and Bi2O3/MnO2 as photocatalyst for the removal of malachite green (MG) and methylene blue (MB). For Malachite Green (MG), the maximum degradation efficiency of Bi2O3, MnO2, and Bi2O3/MnO2 nanocomposite was 96 %, 97 % and 98 % respectively. For methylene blue (MB), the maximum degradation efficiency of Bi2O3, MnO2, and Bi2O3/MnO2 nanocomposite was 95 %, 97 % and 98 % respectively. This work concludes that Bi2O3/MnO2 nanocomposite enhances the degradation efficiency and antibacterial potential.

Optimization of degradation of potassium ethyl xanthate using Fe2O3/TiO2/Flyash nanophotocatalyst using Taguchi statistical approach

Xanthate from mineral processing wastewater is a major threat to the ecosystem. Photocatalysis is emerging as the most effective process with the invention of new nanophotocatalytic materials. The present research focuses on developing the ternary nanocomposite Fe2O3/TiO2/Flyash by a facile hydrothermal method combined with a water bath precipitation method for the efficient degradation of potassium ethyl xanthate (KEX). Taguchi’s experimentation (L16) orthogonal array is used for the optimization of process parameters to get maximum KEX degradation efficiency. The optimized parameters are found to be calcination temperature 400 OC, photocatalyst dosage 0.7 g/L, pH 5, pollutant concentration 10 mg/L, and light intensity 100 W. The percentage contribution of each parameter is obtained through the ANOVA statistical approach as calcination temperature > pH>pollutant concentration > photocatalyst dosage > light intensity. The adsorption mechanism follows the Freundlich isotherm and fits well with pseudo-first-order and second-order kinetics. Material characterization is also done to analyze the crystal structure and morphology of the newly developed nanocomposite to gain a better understanding of the mechanism. This study indicates that the newly developed nanocomposite photocatalyst can effectively degrade potassium ethyl xanthate under light irradiation for 60 min.

Hydrothermally synthesized transition metal doped ZnO nanorods for dye degradation and antibacterial activity

Abstract In this study, Ni-doped ZnO (NZ) and Ni–Mn dual-doped ZnO (NMZ) NPs were synthesized by hydrothermal method. Various analytical techniques, such as XRD, UV–vis, FTIR, PL, SEM, EDAX, and HR-TEM, were employed to investigate the effect of doping transition metal ions in the ZnO lattice. The powder X-ray diffraction (XRD) patterns confirmed a hexagonal structure with average crystallite sizes of 30.66 nm and 27.09 nm for NZ and NMZ nanoparticles, respectively. Tauc’s plot showed that the energy bandgap was redshifted to 2.9 from 2.8 eV by doping transition metal ions in ZnO. The photoluminescence spectrum displayed various peaks, indicating the emission behaviour of the nanomaterials. The photocatalytic performance of the catalysts was tested under visible light sources against Crystal Violet (CV) dye. The degradation efficiency, for NMZ achieved a maximum degradation efficiency of 91.1 %. Antibacterial activity was evaluated against gram-positive (B. subtilis and S. aureus) and gram-negative (E. coli and P. aeruginosa) bacteria. The NMZ exhibited higher photocatalytic and antibacterial activity than NZ.

Harvesting surface (interfacial) energy for tribocatalytic degradation of hazardous dye pollutants using nanostructured materials: A review

AbstractIntroductionTribocatalysis, an emerging cutting‐edge technique that uses frictional mechanical energy to activate the catalytic operation of a reaction or material including nanomaterials has garnered the interest of the research community in recent times.AimThis study aimed to critically review original research works directed toward tribocatalytic degradation of various hazardous dye pollutants. Notably, in this review, various nanomaterials and their composites with outstanding tailored degradation profiles are explored for their tribocatalytic degradation efficiency for various dye pollutants. In addition, the effect of various operating factors that are of importance to engineers, industries, and investors for optimization purposes was pragmatically discussed. Also, the effect of electron trapping and radical scavengers alongside the mechanism of tribocatalytic degradation was empirically analyzed.ResultsFrom this work, it was found that the maximum tribocatalytic degradation efficiency was >80% in most cases at an optimum temperature of 20–40°C, time taken of 0.5‐48 hours, and stirring speed of 500‐1000rmp. It was discovered that magnetic stirring enhances the production of •OH, O2•, and h+ by the nanomaterials that are mechanistically responsible for the degradation of the dye pollutants. Also, it was revealed that expended tribocatalyst can be eluted mostly using H2O and can be reused up to 3–10 times while still sustaining degradation efficiency of >80% in most cases and this suggests the industrial scalability and eco‐friendliness potential of this approach.ConclusionIn the end, challenges and research gaps that can pave the way for method improvement and also serve as future research hotspots for researchers were presented.

Synthesis, characterization and photocatalytic activity of alginate based hybrid material for efficient degradation of organic pollutants under UV light and sunlight irradiation

This study reports the development of alginate based hybrid material (Alg/CuO-gC₃N₄) with copper oxide (CuO) and graphitic carbon nitride (gC₃N₄). The Alg/CuO-gC₃N₄ hydrogel bead was prepared by two step process is as follows: formation of CuO-gC₃N₄ by co-precipitation method and incorporation of CuO-gC₃N₄ in the calcium alginate (Alg) by ionotropic gelation method. The structural and morphological features of the Alg/CuO-gC₃N₄ was characterized using different techniques namely Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Thermogravimetric analysis (TGA), UV Diffuse Reflectance spectroscopy (UV-DRS) and Scanning electron microscopy (SEM). The photocatalytic activity of the Alg/CuO-gC₃N₄ was extensively evaluated by degrading methylene blue (MB) under UV–vis and sunlight irradiation. The influence of various parameters like pollutant type, initial dye concentration, catalyst dosage, effect of pH, light intensity and reusability was investigated. The Alg/CuO-gC₃N₄ achieved a maximum degradation efficiency of 86.26 % and 85.15 % for MB at a dye concentration of 1 × 10−5 M under UV–vis and sunlight irradiation respectively, within 60 min using 0.3 wt% of catalyst dosage. The Alg/CuO-gC₃N₄ exhibited excellent stability and reusability over multiple cycles. Additionally, the incorporation of CuO-gC₃N₄ in alginate facilitates in reducing the bandgap (2.54 to 2.28 eV) for efficient charge separation, further enhancing the overall photocatalytic activity.

Highly Efficient Photocatalytic Degradation of Imidacloprid Based on Iron Metal-Organic Frameworks of Mesoporous NH2-MIL-88b/Graphite Carbon Nitride Nanocomposites by Visible Light Driven in Aqueous Media.

Pesticides that protect crops from insects and other pests are some of the main causes of water pollution. Imidacloprid (IMC) is the most widely used insecticide in the world and should be removed from the environment. This work aims to prepare mesoporous nanocomposites to increase the photodegradation efficiency of IMC. To improve the surface properties and enhance the photocatalytic activity, mesoporous nanocomposites with different weight ratios of graphite carbon nitride (CN = 125, 250, and 500 mg) were prepared by the solvothermal method. Mesoporous NH2-MIL-88b(Fe)/graphite carbon nitride (CN = 250 mg, NH2-MCN-2) nanocomposites showed the best photocatalytic performance. To save the time and cost of the experiments, central composite design (CCD) and response surface methodology (RSM) were used and the results were obtained as the initial concentration of IMC (20 mg L-1), amount of photocatalyst (0.76 g L-1), pH = 5, and degradation time ∼46 min. The maximum photocatalytic degradation efficiency estimated by the model was obtained at 96.31%, which is very close to the actual value of 95.47%. The mesoporous NH2-MCN-2 nanocomposite showed excellent stability and suitable reusability with a maximum degradation of 84.5% after five cycles. Results obtained from kinetic studies indicated a rate constant value of 0.08 min-1, and isotherm models showed that equilibrium data are more consistent with the Langmuir model in photocatalytic degradation. Electrochemical experiments showed significant improvement in the electron transfer rate and photocatalytic activity of the mesoporous NH2-MCN-2 nanocomposite. Different trapping agents were used to investigate the effective active species in IMC photodegradation, and it was determined that the hole (h+) and OH radical (•OH) play the main role. The possible mechanism for IMC photocatalytic degradation was suggested by Mott-Schottky (M-S) electrochemical impedance.

Structural feature, morphology and optical properties of g-C3N4 decorated CuO-Fe3O4 nano composite for electrocatalytic and photocatalytic applications

The present work, novel growth of ternary CuO-Fe3O4/g-C3N4 nanocomposites (NCs) with three different ratio (CuO-Fe3O4:g-C3N4 = 90:10; 75:25 and 50:50), binary CuO-Fe3O4 nanocomposite (NC) and its pristine g-C3N4, CuO and Fe3O4 was synthesized and characterized by XRD, SEM with EDX, TEM, Raman, XPS, UV-DRS and PL. The XRD pattern exhibited the diffraction peaks of g-C3N4 (hexagonal) and CuO (monoclinic) and Fe3O4 (FCC) and the CuO-Fe3O4 mixing of monoclinic and cubic phases along with CuO (−111) direction. The TEM analysis shows the dispersion of CuO-Fe3O4 on g-C3N4 sheets in the CuO-Fe3O4/g-C3N4 (50:50) NC. From the XPS spectra, the oxidation states of Cu2p, Fe2p, O1s, C1s, and N1s, as well as their orbital bonding, are analyzed. The bandgap was calculated by photon energy vs ILD and (F(R∞)hv)2 by using UV-DRS spectrum. The catalyst, CuO-Fe3O4/g-C3N4 (50:50)@NF had a low overpotential of 69 mV at the current density of 10 mA cm2, close to the value of 20 % Pt (45 mV). A chronoamperometry test demonstrated that CuO-Fe3O4/g-C3N4 (50:50)@NF works efficiently for more than 30 h at a high current density of 15 mA cm−2 indicating the strong stability of CuO-Fe3O4/g-C3N4 (50:50)@NF. The maximum photocatalytic degradation efficiency against Rhodamine-B was found to be 99.51 % and crystal violet degradation efficiency is 98.02 % by using CuO-Fe3O4/g-C3N4 (50:50).

Highly efficient electrocatalytic degradation of methylparaben using BiOx-doped Ti/β-PbO2 anode: Comprehensive electrochemical study and degradation mechanism

Electrochemical degradation of methylparaben (MPB) was successfully performed using Ti/β-PbO2-BiOx anode. The structure of the fabricated electrode was characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), thermal gravimetric analysis (TGA), X-ray diffraction (XRD), and mapping techniques. The results confirmed the successful preparation of the electrode with favorable morphological and structural properties. This research includes optimization of operating parameters such as solution pH, applied current density, initial MPB concentration and electrolysis time. The results indicate that the prepared electrode has high electrochemical performance and thermal stability. Under optimal conditions, current density of 4.8 mA/cm2, pH = 5 and initial concentration of 0.5 mM, the maximum degradation efficiency of 98.9 % was obtained. In this work, also, based on the data obtained from LC-MS analysis, a detailed mechanism for the degradation of MPB was proposed. In another section of this research, the electrochemical behavior of MPB on glassy carbon electrode was comprehensively studied using cyclic voltammetry at different pH values. The data obtained from this study provide significant insight into the electrochemical behavior of MPB, its pH-dependent properties and adsorption activities. The results of this section can also be used to better optimize the conditions of MPB degradation.