Effective Photocatalytic Degradation Research Articles

Synergistic adsorption and photocatalytic degradation of tetracycline using a Z-scheme kaolin/g-C3N4/MoO3 nanocomposite: A sustainable approach for water treatment

This research focuses on the synthesis and application of a novel kaolin-supported g-C3N4/MoO3 nanocomposite for the degradation of tetracycline, an important antibiotic contaminant in water systems. The nanocomposite was prepared through a facile and environmentally friendly approach, leveraging the adsorption and photocatalytic properties of kaolin, g-C3N4 and MoO3 nanoparticles, respectively. Comprehensive characterization of the nanocomposite was conducted using techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and optical spectra. The surface parameters were studied using N2 adsorption-desorption isotherm. The elemental composition was studied using X-ray photoelectron spectroscopy. The efficiency of the developed nanocomposite in tetracycline degradation was evaluated and the results revealed an efficient tetracycline degradation exhibiting the synergistic effects of adsorption and photocatalytic degradation in the removal process. The tetracycline degradation was achieved in 60 min. Kinetic studies and thermodynamic analyses provided insights into the degradation mechanism, suggesting potential applications for the nanocomposite in wastewater treatment. Additionally, the recyclability and stability of the nanocomposite were investigated, demonstrating its potential for sustainable and long-term application in water treatment.

CdS@CS/PVA inverse opal films as photocatalyst

We prepared CdS@CS/PVA inverse opal (IO) films by the colloidal photonic crystal (CPC) template method. The photonic structure of the CdS@CS/PVA IO films consists of three-dimensional periodic macropores interconnected by CS/PVA polymers. The as-prepared CdS@CS/PVA IO films were utilized as photocatalysts for the degradation of methylene blue dyes. The degradation rate of methylene blue by the CdS@CS/PVA IO film catalyst was 92%, while that of the CdS@CS/PVA film catalyst was 55% for 6 h. The photocatalytic degradation effect of the CdS@CS/PVA IO film catalyst on methylene blue is [Formula: see text] 1.7 times higher than that of the CdS@CS/PVA film catalyst, which proves that the introduction of the inverse opal structure into the photocatalyst is beneficial to improve the efficiency of the photocatalyst for degrading dyes.

Effective photocatalytic degradation of antibiotic chloramphenicol and anionic direct violet 51 dye using g-C3N4 embedded NiO nanocomposite

Effective photocatalytic degradation of antibiotic chloramphenicol and anionic direct violet 51 dye using g-C3N4 embedded NiO nanocomposite

MXene/ZnS/chitosan-cellulose composite with Schottky heterostructure for efficient removal of anionic dyes by synergistic effect of adsorption and photocatalytic degradation

Nowadays, dye water pollution is becoming increasingly severe. Composite of MXene, ZnS, and chitosan-cellulose material (MX/ZnS/CC) was developed to remove anionic dyes through the synergistic effect of adsorption and photocatalytic degradation. MXene was introduced as the cocatalyst to form Schottky heterostructure with ZnS for improving the separation efficiency of photocarriers and photocatalytic performance. Chitosan-cellulose material mainly served as the dye adsorbent, while also could improve material stability and assist in generation of free radicals for dye degradation. The physics and chemistry properties of MX/ZnS/CC composite were systematically inspected through various characterizations. MX/ZnS/CC composite exhibited good adsorption ability to anionic dyes with adsorption capacity up to 1.29 g/g, and excellent synergistic effects of adsorption and photodegradation with synergistic removal capacity up to 5.63 g/g. MX/ZnS/CC composite performed higher synergistic removal ability and better optical and electrical properties than pure MXene, ZnS, chitosan-cellulose material, and MXene/ZnS. After compounding, the synergistic removal percentage of dyes increased by a maximum of 309 %. MX/ZnS/CC composite mainly adsorbs anionic dyes through electrostatic interactions and catalyzes the generation of •O2−, h+, and •OH to degrade dyes, which has been successfully used to remove anionic dyes from environmental water, achieving a 100 % removal of 50 mg/L dye.

Rational design of CdS-enwrapped polypyrrole nanoparticles for wastewater treatment: removal of hazardous pollutants in aqueous solutions.

The modern world requires a chemical industry that can run at low production costs while producing high-quality products with minimal environmental impact. The development of environmentally friendly, cost-effective, and efficient wastewater treatment materials remains a majorproblem for the sustainable approach. We prepared nanoscale cadmium sulfide (CdS)-enwrapped polypyrrole (PPy) polymer composites for degradation of organic pollutants. The prepared CdS@PPy nanocomposites were characterized by powder X-ray diffraction, scanning electron microscope (SEM), field emission scanning electron microscope (FESEM), Fourier transform infrared spectroscopy (FTIR), and ultraviolet-visible(UV) absorption spectroscopy, indicating proper intercalation between CdS and PPy. Consequently, the catalytic efficiency of the synthesized hybrid nanocomposites was analyzed through the degradation of methylene blue (MB) and rhodamine B (Rh B) under visible light irradiation. The measured degradation efficiency of the dye solutions under the photolysis process is about 18% and 23% for MB and Rh B dye, respectively. Furthermore, the recycle test result concludes that the CdS@PPy composite exhibits 91% and 89% of MB and Rh B dye degradation efficiency even at the 4th cycle, respectively. The positive synergistic impact of CdS and PPymay be the result of effective photocatalytic degradation of MB and RhB.

Construction of BiOCl/bismuth-based halide perovskite heterojunctions derived from the metal-organic framework CAU-17 for effective photocatalytic degradation

The designed synthesis of an S-scheme heterojunction has possessed a great potential for improving photocatalytic wastewater treatment by demonstrating increased the photoredox capacity and improved the charge separation efficiency. Here, we introduce the fabrication of a heterojunction-based photocatalyst comprising bismuth oxychloride (BiOCl) and bismuth-based halide perovskite (BHP) nanosheets, derived from metal-organic frameworks (MOFs). Our composite photocatalyst is synthesized through a one-pot solvothermal strategy, where a halogenation process is applied to a bismuth-based metal-organic framework (CAU-17) as the precursor for bismuth sourcing. As a result, the rod-like structure of CAU-17 transforms into well-defined plate and nanosheet architectures after 4 and 8 h of solvothermal treatment, respectively. The modulation of the solvothermal reaction time facilitates the establishment of an S-scheme heterojunction, resulting in an increase in the photocatalytic degradation efficiency of rhodamine B (RhB) and sulfamethoxazole (SMX). The optimized BiOCl/BHP composite exhibits superior RhB and SMX degradation rates, achieving 99.8% degradation of RhB in 60 min and 75.1% degradation of SMX in 300 min. Also, the optimized BiOCl/BHP composite (CAU-17-st-8h sample) exhibited the highest rate constant (k = 3.48 × 10−3 min−1), nearly 6 times higher than that of the bare BHP in the photocatalytic degradation process of SMX. The enhanced photocatalytic efficiency can be endorsed to various factors: (i) the in-situ formation of two-components BiOCl/BHP photocatalyst, derived from CAU-17, effectively suppresses the aggregation of pristine BHP and BiOCl particles; (ii) the S-scheme heterostructure establishes a closely-knit interfacial connection, thereby facilitating efficient pathways for charge separation/transfer; and (iii) the BiOCl/BHP heterostructure enhances its capacity to absorb visible light. Our investigation establishes an effective strategy for constructing heterostructured photocatalysts, offering significant potential for application in photocatalytic wastewater treatment.

Modulating of Bi2MoO6-based photocatalyst through manipulation of reactant ratios for enhanced visible light photocatalytic activity

In this work, a novel photocatalyst, comprising of Bi2MoO6 and Bi2O2(OH)(NO3), was successfully synthesized by the one-pot hydrothermal method, thereby illuminating an innovative avenue for structure modulation of Bi2MoO6. The characterizations proved the facile attainability of controllable modifications in the microstructure and morphology of Bi2MoO6. The comprehensive appraisal of the synergistic adsorption-photocatalytic performances of the composites in the context of ciprofloxacin (CIP) was carried out. The findings presented compelling evidence that the amalgamation of Bi2MoO6/Bi2O2(OH)(NO3) exhibited an extraordinary adsorption capacity and photocatalytic activity when compared with the pristine Bi2MoO6 and Bi2O2(OH)(NO3). By virtue of its high surface area and pore volume, the optimized BMO/BON manifested a CIP adsorption capacity that surpassed that of Bi2MoO6 and Bi2O2(OH)(NO3) by approximately 2.4 and 11.2 times, respectively. Furthermore, through the concerted effects of adsorption and photocatalytic degradation, BMO/BON demonstrated an impressive CIP removal efficiency of 99.2 % following a mere 30 min of visible light exposure. The reaction rate constant was found to be approximately 0.124 min−1 for BMO/BON, surpassing that of Bi2MoO6 and Bi2O2(OH)(NO3). The augmentation in the photocatalytic activity of BMO/BON can be ascribed to its diminutive crystalline dimensions, large specific surface area, and narrowed bandgap. Thus, this investigation introduces a practical and ingenious strategy for the tuning of the Bi2MoO6 structure by manipulation of reactant ratios, showcasing significant implications in the realm of catalysis.

Nanotransfer Printing of Functional Nanomaterials on Electrospun Fibers for Wearable Healthcare Applications

AbstractWith the advancement of functional textile technology, there is a growing demand for functional enhancements in textiles from both industrial and societal perspectives. Recently, nanopattern transfer technology has emerged as a potential approach for fabricating functional textiles. However, conventional transfer methods have some limitations such as transfer difficulties on curved fiber surfaces, polymer residues, and delamination of transferred nanopatterns. In this study, an advanced nanopattern transfer method based on surface modification and thermoforming principles is applied to microscale electrospun fibers. This transfer method utilizes covalent bonding and mechanical interlocking between nanopatterns and the fibers without requiring extra adhesives. Various nanopatterns transferred electrospun fibers possess significant potential for diverse wearable healthcare applications. This work introduces two specific application scenarios in the field of wearable healthcare, both of which leverage the light: diagnostics and antimicrobials. Versatile textile with silver nanogap‐pattern detects glucose in sweat, diagnosing hypoglycemia and diabetes by shifting Raman peaks from 1071.0 to 1075.4 cm−1 for 0 to 150 µm glucose. Additionally, a bactericidal mask using visible light to induce the photocatalytic degradation effect of titanium dioxide and silver nanopatterns is developed. Bactericidal efficacy against Escherichia coli and Staphylococcus aureus is 99.9% due to photolysis from visible light irradiation.

Integration of Ag2S QDs in 3D Zn3V2O8 nanoflower for visible light driven effective photocatalytic degradation of rifampicin: Insights into preparation, mechanism and by-product toxicity evaluation

Water contamination is regarded as one of the most important concerns in the last decade and its crucial to develop an efficient and productive technique to remediate organic pollutants from waters. Photocatalytic degradation processesare advanced oxidation procedure and a promising technique for the degradation of organic pollutants. In this study, we fabricated Ag2S/Zn3V2O8 nanocomposite (AS/ZVO NCs) for the degradation of rifampicin (RIF) by ultrasonicated co-precipitation strategy. The NCs was optimally synthesized with varying deposition concentrations, among which 5%-Ag2S/Zn3V2O8 (5%-AS/ZVO) exhibited superior photocatalytic activity (95.5%) under visible light irradiation. Moreover, the experiments were conducted at diverse operational parameters such as different NCs dosage, different concentration of RIF, pH, and ions, to investigate the impact on the photocatalytic degradation of RIF. Notably, XRD and XPS results of used 5%-AS/ZVO NCs demonstrated commendable stability and possess sustained integrity in structure after six consecutive cycle tests. The scavenging study and radical trapping experiments confirmed the formation of •OH and O2•- during photocatalytic reaction. The mechanism of photocatalytic degradation of RIF by 5%-AS/ZVO NCs was proposed and the pathway was predicted based on the GC-MS results. The current study provides a comprehensive understanding for designing efficient photocatalysts for the environmental remediation applications.

Facile green synthesis of SnO2:Zn@g-C3N4 heterojunction nanocomposite using Murraya paniculata leaves extract for effective photocatalytic degradation of organic dye malachite green by sunlight illumination

In this work nanocomposite heterojunction of SnO2:Zn conjugated with g-C3N4 was successfully synthesized by a green synthesis method using Murraya paniculata leaves extract. Materials were characterized by XPS, FTIR, XRD, BET, HRTEM, FESEM, EDAX, and UV–visible spectrophotometer. XRD and HRTEM results revealed the formation of highly crystalline and small sized particles having mean grain size of 4.4 and 4.9 nm for SnO2:Zn and SnO2:Zn@g-C3N4, respectively and interplanar spacing of 0.333 nm. The 2-D sheeted structure of g-C3N4 acts as a translucent layer that captures and provide a considerable extent of self-agglomeration on the underlying sphere shaped SnO2:Zn NPs which results in excellent charge flow which eventually results in enhanced photocatalytic degradation performance of the synthesized heterojunction. The XPS analysis verifies the presence of Sn, Zn, O, C, and N in the synthesized heterojunction SnO2:Zn@g-C3N4. The UV–Visible and photoluminescence spectra helped to demonstrate the effective inhibition of excitons annihilation within the heterojunction nanocomposite. The heterojunction shows an excellent photodegradation efficiency of 93.84 % in the process of photodegradation of dye Malachite green (MG). Effect of pH, catalyst dose on photodegradation and the recyclability were also investigated. The kinetic plots were used to calculate the rate constant which shows the nature of a pseudo first order reaction with a rate constant of 0.299 min−1. Trap experiments were conducted to confirm the role of h+ and O2.− as active species.

Studies on Effective Photo-catalytic Degradation of Rhodamine-B Using Metal-Doped Oxidized-Activated Carbon: Kinetics, Isotherm Models and Degradation Mechanism

Studies on Effective Photo-catalytic Degradation of Rhodamine-B Using Metal-Doped Oxidized-Activated Carbon: Kinetics, Isotherm Models and Degradation Mechanism

Magnetic Fe3O4 nanospheres supported N/S-SnO2 nanorod for highly effective visible light photocatalytic degradation of tetracycline

The global health landscape is increasingly threatened by antimicrobial resistance, prompting a search for pioneering interventions. The current study focused on the construction of non-metal doped SnO2 nanorod decorated with Fe3O4 nanospheres through hydrothermal techniques. The prepared N/S-SnO2@Fe3O4 nano-heterojunction was evaluated by performing photocatalytic degradation of tetracycline (TET) under visible light illumination. Out of various combinations tested, S-SnO2@Fe3O4 nano-heterojunction was found to degrade TET by 98.3% with a TOC removal of 97%. S-SnO2@Fe3O4 nano-heterojunction and its constituents were characterized by using TEM, SEM, XRD, DRS, PL, Raman, XPS, EIS, BET and FTIR. The influence of factors such as pH, ions, S-SnO2@Fe3O4 dosage and TET concentration on photodegradation were investigated. Furthermore, the stability and reusability of S-SnO2@Fe3O4 nano-heterojunction were assessed through six consecutive cycles of TET photodegradation. XPS and XRD analyses characterized the recovered nano-heterojunction, while scavenging assays and ESR analysis identified as •OH is the main reactive oxygen species involved in TET photodegradation. Additionally, GC-MS/MS analysis proposed a photodegradation pathway, and ECOSAR was used to predict the toxicity of intermediates.

Double-layered solar evaporator based on polymeric ionic liquid grafted attapulgite and MXene/PPy for efficient desalination and photodegradation

Solar-driven interfacial evaporation (SIE) is a promising fresh water acquisition technology to address the global water resource shortage. Therefore, solar evaporators with efficient photothermal conversion efficiency and multifunctional purification capabilities are still in high demand. At present, a variety of photothermal conversion materials have been explored, however, there are few studies on integrating interfacial evaporation and photocatalytic capabilities into one solar steam generation system collaboratively. In this work, a new double-layered solar interfacial evaporator (MXene/PPy-ACA) was fabricated by using polymeric ionic liquid grafted attapulgite (ATP-PIL) as the matrix and modified the upper surface by MXene and polypyrrole (PPy). The evaporator can not only carry out seawater desalination efficiently, but also has good photocatalytic degradation effect on organic dyes. The MXene/PPy-ACA achieves an evaporation rate of 1.53 kg m−2 h−1 and corresponding to an efficiency of 92.17 % under irradiation of 1 sun. In addition, duing to the ionic repulsion effect of ATP-PIL, the MXene/PPy-ACA possesses good salt resistance. When tested in 20 wt% high brine, the evaporation rate is measured to be 1.40 kg m−2 h−1. Moreover, owing to the superb photocatalytic properties of MXene and PPy, the MXene/PPy-ACA exhibits remarkable photocatalytic efficiency towards organic dyes, achieving degradation rates of 94.9 %, 67.49 %, and 65.11 % for methyl orange (MO), rhodamine B (RhB), and methylene blue (MB), respectively. The prepared interfacial evaporation system can also run stably in acid and alkali solution, and has a good practical application prospect. This study may offer an alternative approach in achieving clean water via SIE of seawater and complex wastewater.

Synthesis of highly conductive carbon quantum dot-enhanced Z-scheme BiOBr/g-C3N4 heterojunction for effective photocatalytic degradation of tetracycline hydrochloride

BiOBr can effectively mitigate the ecological and environmental problems caused by pollution with antibiotics, and its photocatalytic properties can be improved by utilizing heterojunction structures and cocatalysts. In this study, the Z-scheme heterojunction ternary photocatalyst BiOBr/g-C3N4/CQDs (BCCx) was obtained by using an uncomplicated electrostatic self-assembly process. The incorporation of carbon quantum dots (CQDs) with high conductivity provided a conduit for charge transfer between g-C3N4 and BiOBr. The loading density of CQDs on BiOBr/g-C3N4 could be rapidly adjusted by changing the concentration of the CQDs precursor in solution. The presence of CQDs enhanced the absorption of visible light and inhibited the synthesis of photogenerated charge carriers, thereby resulting in a synergistic effect on the Z-scheme heterojunction and improving the photocatalytic properties under visible light. In particular, BCC50 had the highest catalytic performance, with a tetracycline pollutant degradation efficiency of 100% within 60 min. The degradation efficiency remained above 95% even after repeated use in five cycles. The principles of semiconductor energy bands and internal electrostatic field generation are applied to explain the photocatalytic mechanism responsible for tetracycline degradation using BiOBr/g-C3N4/CQDs.

Effective photo-catalytic degradation of Malachite Green with water stable Cu based aliphatic di-carboxylate MOFs

Four different mesoporous Cu-MOFs named as Cu(Pima), Cu(Suba), Cu(Azla) and Cu(Seba) were prepared from aliphatic di-carboxylate linkers with the dimeric Cu paddle wheels as Secondary Building Units (SBUs). These as-synthesized aliphatic Cu-MOFs were applied as fresh heterogeneous catalysts for the catalytic wet peroxide oxidation of simulated Malachite Green waste-water and characterized using PXRD, FT-IR, Fe-SEM and BET. The results exhibited a better catalytic degradation efficiency of Cu(Seba) and Cu(Azla) (>90% in 200 mins) as compared to Cu(Pima) and Cu(Suba). It was established that degradation efficiency of Cu(seba) was approximately 9.8 times better than the rest of the synthesized Cu(MOFs). It was recognized that increasing the organic linker length can evidently boost the dye degradation process. Under optimum conditions, the degradation efficiency of 98% and 97% for Cu(Seba) and Cu(Azla) were achieved respectively. A optimal condition of 1.0 mL H2O2, 50 °C temperature and 3.5 pH was obtained. A recyclability experiment of four runs was performed for Cu(Seba) and Cu(Azla) which exhibited they maintained an effective degradation efficiency of ∼80% simulated MG solution. These analytical results of the degradation efficiency for Cu(Seba) and Cu(Azla) led us on a conclusion that, as synthesized Cu-MOFs outperformed several other reported MOFs, nanoparticles, adsorbents etc., as heterogeneous catalysts in the field of dye degradation for wastewater treatment.

Gold-Deposited Graphene Nanosheets for Self-Cleaning Graphene Surface-Enhanced Raman Spectroscopy with Superior Charge-Transfer Contribution.

The interaction of graphene with metals initiates charge-transfer interaction-induced chemical enhancements, which critically depend on the doping effect from deposited metallic configurations. In this paper, we have explored the gold nanoparticle-decorated monolayer graphene nanosheets for the large graphene-induced Raman enhancement of adsorbed analytes, indicating the surface-enhanced Raman spectroscopy (SERS) capabilities of metal-doped graphene (G-SERS). Here, the systematically sputtered Au thickness optimization procedure revealed noticeable modifications in the graphene Raman spectra and photoluminescence (PL) background quenching, which indicated favorable charge transfer through n-type doping of chemical vapor deposition-grown graphene nanosheets. The highly consistent, individually distributed morphology of the gold nanoislands over graphene nanosheets depicted a reproducibly uniform G-SERS signal with excellent relative standard deviation values (<5%), resulting in the strongest Raman intensity enhancement factors of ∼108 (MB) (methylene blue) and 107 (DPA) (2,6-pyridinedicarboxylic acid) composed of the weakest PL background. The combined charge-transfer-induced chemical enhancement and electromagnetic enhancement from individual Au nanoislands result in a lowering of detectability down to 10-16 M (MB) and 10-11 M (DPA) concentrations with efficient time-dependent signal stability. Additionally, the GAu demonstrated its effective (∼94.4%) photocatalytic degradation capabilities by decomposing MB dye molecules from a concentration of 1 μM to 2.52 fM within 60 min. Therefore, the prominent charge-transfer contribution through controlled Au decoration over graphene nanosheets provides a potential strategy for fabricating superior SERS sensors and photocatalysts exhibiting adequate signal consistency, stability, and photodegradation efficiency through overcoming the limitations of the traditional sensing platforms.

Two-step growth of alumina nanoparticle decorated graphene oxide surfaces: Effect on photocatalytic activity

As water pollution is increasing due to industrialization, there is a high demand for easy-processing photocatalytic materials to clean wastewater. Here, the improvement in the photocatalytic dye degradation effect of graphene oxide (GO) surfaces, made of ultra-sonication assisted modified Hummer's method, is demonstrated with increasing alumina (Al2O3) concentration in the range of 4–30 wt. %. Scanning electron microscopy and x-ray diffraction results suggest a gradual increment in crystalline Al2O3 nanoparticles (NPs) by reducing GO, in good agreement with the first-principles calculations. Moreover, x-ray photoelectron spectroscopy reveals the appearance of oxygenated functional groups with increasing Al2O3 concentration, leading to the formation of defect-rich GO as demonstrated by Raman spectroscopy. Ultraviolet-visible spectroscopy further reflects a maximum reduction in the optical bandgap from 1.88 to 1.56 eV up to a concentration of 15 wt. % Al2O3. Interestingly, the methylene blue degradation efficiency of GO under ultraviolet irradiation is also found to be improved from 45% to 64% with 15 wt. % Al2O3, whereas the formation of Al2O3 NPs in the range of 100–300 nm with 30 wt. % Al2O3 is found to be detrimental for photocatalytic activity.

Construction of p-n-p nano heterojunction through coupling La2O3, (BiO)2CO3 and Ag3PO4 for effective photocatalytic degradation of doxycycline: Insights into mechanism, pathway and intermediate toxicity evaluation

The present work is centred around the development of La2O3/(BiO)2CO3/Ag3PO4 (LBA), a p-n-p nano-heterojunction to photodegrade doxycycline under visible light irradiation. Here, ultrasonication assisted co-precipitation method was employed to synthesize the photocatalyst. The photocatalyst was characterized using different analysis such as SEM, TEM, elemental mapping, XRD, XPS, FTIR, Raman, BET, DRS, PL and EIS which confirmed the successful fabrication of LBA and their excellent ability to refrain the e−/h+ recombination owing to the construction of the heterojunction. LBA was found to degrade DOX by 91.75 % with the high mineralization of 87.23%. The impact of the reaction parameters influencing the photodegradation process including the concentration of the NCs and DOX, pH and the influence of the commonly present anions were studied. The stability and reusability of the LBA was assessed through subjecting it to four cycles of photodegradation of DOX. In addition, the recovered LBA was characterized through XPS and XRD analysis to confirm the particles stability and reusability. The active participation of the photogenerated charges and the reactive oxygen species were identified through the scavenging assay and ESR analysis. Further, GC-MS/MS analysis was performed to put forward a plausible photodegradation pathway. The toxicity of the end products as well as the intermediates was predicted through ECOSAR software.

CdTe QDs@SiO2 composite material for efficient photocatalytic degradation of tetracycline composites

In the contemporary context, tetracycline is widely utilized as a prevalent antibiotic in various facets of life. However, the excessive use of antibiotics has caused visible environmental consequences. Henceforth, the scientific community has increasingly focused on developing catalysts that exhibit exceptional efficacy in the proficient degradation of tetracycline. In this study, a novel nanomaterial was developed to encapsulate CdTe quantum dots (QDs) with a SiO2 shell. The distinct synthesis approach generated a composite material that showed heterogeneity and considerably increased the contact area with contaminants. Consequently, the transfer of photoelectron to the SiO2 spheres was significantly improved, leading to a more efficient separation during the catalytic process. The study investigated how different factors, such as the loading of the catalyst, the initial concentration of tetracycline, pH levels, and the wight ratio of CdTe QDs (SiO2 + CdTe QDs) affected the effectiveness of photocatalytic tetracycline degradation. The findings indicated that the optimal degradation efficiency was observed at a catalyst concentration of 0.25 g/L and a solution pH of 9, leading to an impressive degradation rate of 96% within a mere 2 h timeframe.

New Y0.045Ni0.045Fe2.91O4 nanowires decorated over mesoporous silica for crystal violet removal: Response surface methodology optimization, kinetics, and isothermal studies

Recently, there has been considerable interest in developing an efficient, easily separable, cost-effective, and environmentally friendly catalyst for treating toxic environmental pollutants. In this study, we successfully designed yttrium–nickel-doped magnetite nanowires (Y0.045Ni0.045Fe2.91O4) and their mesoporous silica (MS)-coated composite (Y0.045Ni0.045Fe2.91O4/MS) using a simple coprecipitation method. The resulting composite demonstrated effective adsorption and photocatalytic degradation of crystal violet (CV) dye under sunlight. Various instrumental characterization techniques were employed to assess the nanowires' morphological, chemical, and surface functional properties and their composite. The existence of metal–oxygen bonds in Y0.045Ni0.045Fe2.91O4 within the 500–800 cm−1 range was verified through FTIR analysis. According to the Brunauer–Emmett–Teller analysis, the composite exhibited a surface area of 285 m2/g, a pore volume of 0.436 cm³/g, and an average pore width of 5 nm. The composite's high surface area and mesoporous nature underscored its porous structure, confirming its enhanced adsorption capacity for contaminants. High resolution XPS spectrum justified the presence of surface silanol groups (Si–OH) which are responsible for adsorption phenomena. Photocatalytic experiments revealed that Y0.045Ni0.045Fe2.91O4 nanowires and their composites achieved 89% and 90% degradation rates for CV dye within 60 and 10 min, respectively. The removal efficiency was assessed under optimized conditions of pH (8), dose (15 mg), time (60 and 10 min), and concentration (10 mg/L). Statistical analysis revealed that pH significantly impacted CV dye removal because functional group activation varied at different pH values. To elucidate the adsorption mechanism and kinetics, the Temkin isotherm model and pseudo-second-order kinetics model (R2 = 1.996 mg min−1) were the best fit for the composite. Furthermore, approximately 99% of the nanowires were magnetically separated from the reaction mixture in an external magnetic field. The demonstrated synergy of efficient adsorption–photocatalysis, coupled with easy recovery, suggests that innovatively designed nanomaterials are optimal for the water remediation of organic pollutants in wastewater.