Rhodamine B Solution Research Articles

Microwave-assisted synthesis of carbonized polymer dots/CdS quantum dots/Bi2WO6 Z-scheme heterojunctions: Enhancing photocatalytic environmental remediation via dual-quantum dot heterostructures.

The fabrication of dual-quantum dot heterostructures offers a promising strategy to enhance the environmental remediation performance of photocatalysts. Herein, a Bi2WO6-based Z-scheme heterojunction was constructed by incorporating carbonized polymer dots (CPDs) and CdS quantum dots (QDs) via a microwave-assisted solvothermal method. The 1wt% CPDs/CdS QDs/Bi2WO6 (CCBW-1) composite achieved optimal Cr(VI) removal, reaching 97.7% within 30min under 10W LED light, with rate constants 4.4, 2.8, and 10.1 times higher than those of pristine Bi2WO6, CdS QDs/Bi2WO6, and 3% CPDs/Bi2WO6, respectively. Notably, the composite also demonstrated 96.9% Cr(VI) and 98.1% Rhodamine B (RhB) removal within 30min in a mixed Cr(VI) and RhB solution. The formation of strong BiS and WOCd bonds at the Bi2WO6CdS QD interface facilitates intimate interfacial contacts and creates atomic-scale "highways" that accelerate charge transfer. Additionally, the electron-donating effects of the NH2 and OH functional groups on the CPDs further enhance carrier transfer efficiency. The Z-scheme electron transport pathway enables CCBW-1 to capitalize on the deep reduction potentials and extended light absorption of the dual-QDs, allowing them to act synergistically as active centers. By integrating experimental data with theoretical calculations, the photocatalytic mechanism, potential intermediates, photodegradation pathway, and biological toxicity were comprehensively elucidated.

Solvent-modified carbon nitride integrated with SiO2 for enhanced photocatalytic activity: Microstructural modification and catalytic mechanisms

The photocatalytic activity of carbon nitride (CN) materials is primarily limited by low photogenerated carrier separation and mobility. The solvothermal method can regulate the molecular structure of materials to enhance charge separation and transport. In this study, we used ethanol (EtOH), DMF, and deionized water (H2O) as solvents to customize the microstructure of CN through a one-step solvothermal method and loaded SiO2 onto CN, ultimately synthesizing SiO2/CN composites (SiCNX, where X = E, D, H) with significantly improved photocatalytic efficiency. The modification with these three solvents led to noticeable changes in the basic structure of CN, reflected in the number of carbon vacancies, the integrity of the tri-s-triazine ring framework, the degree of polymerization, and the presence of C–C/CC bonds. The SiCNE composite, synthesized with ethanol modification, stood out by demonstrating exceptional photocatalytic degradation ability for Rhodamine B (RhB), achieving 99 % decolorization of a high-concentration RhB solution (300 mg/L) in 35 min. Additionally, the performance of SiCNE is 6.24 times that of CN and 224 times that of SiO2. This study not only exhibits the potential of solvent-modified SiCNX in constructing efficient electron transfer pathways but also highlights its capability in remarkably improving photocatalytic performance, providing a promising avenue for the development of future photocatalytic materials.

Fabrication and application of a dual drug-loaded nanoniosomes encapsulating rutin and berberine: optimization, in vitro and ex vivo evaluation

Rutin and berberine are naturally occurring polyphenols but their usefulness is restricted by their low bioavailability and poor solubility. Thus, by delivering rutin–berberine in the form of niosomes simultaneously and hoped to enhance the permeability through nasal route for the treatment of depression. Thin-film hydration approach was used to generate dual drug-loaded niosomes (rutin–berberine) encapsulating rutin and berberine. Various analytical techniques were used to characterize the morphology, size, compatibility, and leakage of the particles. These techniques included transmission electron microscopy, dynamic light scattering, UV spectrophotometry, and differential scanning calorimetry. The optimized formulation (rutin–berberine optimized niosomal formulation) was subjected to additional characterization for drug release, ex-vivo penetration investigation, confocal laser scanning microscopy, and 2,2-diphenyl-1-picrylhydrazyl assay. The rutin–berberine optimized niosomal formulation analysis showed that the drug release was 76.66 ± 1.24% at 24 hours, the entrapment efficiency was 74.8 ± 2.13% (rutin), and 79.0 ± 3.47% (berberine) and the vesicle size was 72.6 nm with a polydispersion index of 0.208. The antioxidant activity showed 73.67 ± 2.5% which is close to regular ascorbic acid. Studies on permeation ex-vivo revealed that rutin–berberine optimized niosomal formulation had considerably higher permeation (84.89 ± 3.15%) compared to rutin–berberine suspension (37.28 ± 2.33%). Furthermore, rhodamine B-loaded rutin–berberine optimized niosomal formulation appeared to have higher penetration than the control (rhodamine B-solution) according to the confocal laser scanning microscope results of the nasal mucosa. Based on all the experimental data, rutin–berberine optimized niosomal formulations were determined to be a viable and successful intranasal delivery formulation.

Application of Box-Behnken design for the optimization of Khellin-loaded ethosomes formulation for the management of psoriasis in mice

The objective of the present study was to develop and optimize Khellin-loaded ethosomes formulation to enhance the topical delivery of Khellin for the management of psoriasis. Based on vesicle size, polydispersity (PdI) and encapsulation efficiency, the formulation was optimized using the "3-factor 3-level", Box-Behnken design (BBD). Antioxidant, Anti-inflammatory and Anti-psoriatic activity were further assessed for the optimized formulation. The optimized formulation carried vesicles with a size of 214.64 ± 0.04 nm, PdI 0.387 ± 0.001 and an encapsulation efficiency of 68.38 ± 0.01%. Rhodamine-B loaded formulation was applied to mice skin, and the penetration depth was measured using confocal laser scanning microscopy (CLSM). It was found that the Rhodamine-B solution penetrated mice’s skin to a depth of 20.0 µm. However, the Rhodamine-B loaded ethosomes formulation penetrated mice’s skin to a depth of 55.0 µm. Further, the Khellin-loaded ethosomes formulation possessed strong antioxidant activity, presented a good reduction in paw edema, and showed good anti-inflammatory activity. In addition, the prepared Khellin-loaded ethosomes formulation exhibited considerable effects against psoriasis.

A Reactor based on P‐N Heterojunction of Polypyrrole and Porous Silicon for Photocatalytic and Electro‐assisted Photocatalytic Performance

AbstractIn this work, a photoelectrochemical reactor with an anode based on hybrid structure between conducting polymer polypyrrole (PPy) and porous silicon (PSi) was fabricated and utilized to evaluate the photocatalysis and electro‐assisted photocatalysis for degradation of rhodamine B (RhB) solution. The PSi was made of n‐type silicon single‐crystal wafer by the metal‐assisted chemical etching (MACE). The anode PPy/PSi formed following a polymerization of the PPy on the PSi from the vapour‐phase route using oxidant FeCl3. Typical material characterizations of the PPy, PSi and PPy/PSi were investigated via scanning electron microscope (SEM), and spectroscopies of Fourier‐transform infrared (FTIR), Raman scattering and UV‐vis. Under visible light radiation (halogen light with the wavelength region of 400–700 nm), photocatalytic and electro‐assisted photocatalytic processes of the reactor were conducted by degradation of the RhB solution. A heterojunction (p‐n) of the PPy/PSi was proposed to explain the efficient catalytic performance of the reactor.

Surprising Effects of Al2O3 Coating on Tribocatalytic Degradation of Organic Dyes by CdS Nanoparticles

With a band gap of 2.4 eV, CdS has been extensively explored for photocatalytic applications under visible light irradiation. In this study, CdS nanoparticles have been investigated for the tribocatalytic degradation of concentrated Rhodamine B (RhB) and methyl orange (MO) solutions. For CdS nanoparticles in a glass beaker, 78.9% of 50 mg/L RhB and 69.8% of 20 mg/L MO solutions were degraded after 8 h and 24 h of magnetic stirring using Teflon magnetic rotary disks, respectively. While for CdS nanoparticles in a beaker with Al2O3 coated on its bottom, 99.8% of the RhB solution was degraded after 8 h of magnetic stirring and 95.6% of the MO solution was degraded after 12 h of magnetic stirring. Moreover, another contrast was observed between the two beaker bottoms—a new peak at 250 nm in UV–visible absorption spectra was only observed for the MO degradation by CdS in the as-received glass beaker, which indicates that MO molecules were only broken into smaller organic molecules in that case. These findings are meaningful for expanding the catalytic applications of CdS and for achieving a better understanding of tribocatalysis as well.

Morphology-Dependent Photocatalytic Activity of Nanostructured Titanium Dioxide Coatings with Silver Nanoparticles.

This study aims to improve the photocatalytic properties of titanium dioxide nanorods (TNRs) and other related nanostructures (dense nanorods, needle-like nanorods, nanoballs, and nanoflowers) by modifying them with silver nanoparticles (AgNPs). This preparation is carried out using a two-step method: sol-gel dip-coating deposition combined with hydrothermal crystal growth. Further modification with AgNPs was achieved through the photoreduction of Ag+ ions under UV illumination. The investigation explores the impact of different growth factors on the morphological development of TiO2 nanostructures by modulating (i) the chemical composition, the water:acid ratio, (ii) the precursor concentration involved in the hydrothermal process, and (iii) the duration of the hydrothermal reaction. Morphological characteristics, including the length, diameter, and nanorod density of the nanostructures, were analyzed using scanning electron microscope (SEM). The chemical states were determined through use of the X-ray photoelectron spectroscopy (XPS) technique, while phase composition and crystalline structure analysis was performed using the Grazing Incidence X-ray Diffraction (GIXRD) method. The results indicate that various nanostructures (dense nanorods, needle-like nanorods, nanoballs, and nanoflowers) can be obtained by modifying these parameters. The photocatalytic efficiency of these nanostructures and Ag-coated nanostructures was assessed by measuring the degradation of the organic dye rhodamine B (RhB) under both ultraviolet (UV) irradiation and visible light. The results clearly show that UV light causes the RhB solution to lose its color, whereas under visible light RhB changes into rhodamine 110, indicating a successful photocatalytic transformation. The nanoball-like structures' modification with the active metal silver (TNRs 4 Ag) exhibited high photocatalytic efficiency under both ultraviolet (UV) and visible light for different chemical composition parameters. The nanorod structure (TNRs 2 Ag) is more efficient under UV, but under visible-light photocatalyst, the TNRs 6 Ag (dense nanorods) sample is more effective.

Designing Zn-MOF/AgCl composites for the photocatalytic degradation of rhodamine B dye and tetracycline antibiotic

The agglomeration tendency of AgCl, as a photocatalyst, hampers its advancement and practical application. In this paper, a simple composite method is designed based on the precipitation characteristics of AgCl. Ag+ ions introduced from outside combines with Cl− anions in complex [Zn(L)Cl]n (M1) [L = 2-(1-(carboxymethyl)-1H-benzo [d] imidazol-3-ium-3-yl)acetate)] to directly form Zn-MOF/AgCl composites (ZA-x, x = 0.5, 1 and 2), which may effectively prevent agglomeration of AgCl. The morphology and structure analysis displays a remarkable dispersity of AgCl. Further characterization and analysis of PL, UV–Vis, EIS, and TPC reveal that the composites have potential as excellent photocatalysts. The subsequent visible light catalytic degradation of Rhodamine B (RhB) and tetracycline hydrochloride (TC) has shown that the optimal composite ZA-0.5 with M1 to AgCl ratio of 1:0.5 exhibits the highest degradation efficiency in the 20 mg/L solution of RhB or TC, achieving 99.1 % for RhB within 20 min and 81.9 % for TC within 50 min. The free radical trapping test shows that ⋅O2− is the main catalytic species in the degradation process. In addition, the possible degradation mechanism was analyzed by VB-XPS and LC-MS. In a word, the in-situ combination of Cl− in M1 with Ag+ improves the dispersity of AgCl, enhances the interaction between M1 and AgCl, and leads to the effetive separation of electrons and holes, therefore improving the photocatalytic performance.

Construction of Ternary Heterostructured NaNbO<sub>3</sub>/Bi<sub>2</sub>S<sub>3</sub>/ Ag Nanorods with Synergistic Pyroelectric and Photocatalytic Effects for Enhanced Catalytic Performance

The removal of dyes and pathogens from contaminated water remains a significant challenge. In the present study, NaNbO3 and NaNbO3/Bi2S3 powders were prepared by a simple hydrothermal method, and then the noble metal Ag was successfully deposited on NaNbO3/Bi2S3 by photoreduction to constitute the NaNbO3/Bi2S3/Ag ternary nanorods heterostructure. With continuous visible light irradiation and controlled temperature variation (25-55 °C), the monomeric NaNbO3 could degrade 73.3% of Rhodamine B (RhB) and inactivated 46% of Salmonella while the ternary complex NaNbO3/Bi2S3/Ag showed a higher RhB degradation efficiency of 94.9% as well as an higher sterilization efficiency of 82%. In addition, after four replicate experiments, NaNbO3/Bi2S3/Ag still had a high degradation efficiency. Compared with NaNbO3 monomer, NaNbO3/Bi2S3/Ag possessed stronger catalytic ability. The improvement of catalytic activity could be attributed to the efficient separation of pyroelectric and photocatalytic electrons and holes through the formation of NaNbO3/Bi2S3/Ag heterostructural nanorod. Keywords: Ternary heterostructures; Nanocomposites; Pyroelectricity; RhB solution degradation; Salmonella sterilization

Surprising Effects of Ti and Al2O3 Coatings on Tribocatalytic Degradation of Organic Dyes by GaN Nanoparticles.

GaN is more stable than most metal oxide semiconductors for the photocatalytic degradation of organic pollutants in harsh conditions, while its catalytic efficiency has been difficult to be substantially improved. In this study, the tribocatalytic degradation of organic dyes by GaN nanoparticles has been investigated. Stimulated through magnetic stirring using homemade Teflon magnetic rotary disks in glass beakers, the GaN nanoparticles were found to induce negligible degradation in rhodamine B (RhB) and methyl orange (MO) solutions. Surprisingly, the degradation was greatly enhanced in beakers with Ti and Al2O3 coatings on their bottoms: 99.2% and 99.8% of the 20 mg/L RhB solutions were degraded in 3 h for the Ti and Al2O3 coatings, respectively, and 56% and 60.2% of the 20 mg/L MO solutions were degraded in 24 h for the Ti and Al2O3 coatings, respectively. Moreover, the MO molecules were only broken into smaller organic molecules for the Ti coating, while they were completely degraded for the Al2O3 coating. These findings are important for the catalytic degradation of organic pollutants by GaN in harsh environments and for achieving a better understanding of tribocatalysis as well.

Facile construction of copper-doped metal organic framework as a novel visible light-responsive photocatalyst for contaminant degradation

ABSTRACT Metal–organic frameworks (MOFs) with photocatalytic activity have garnered significant attentions in environmental remediation. Herein, copper-doped zeolitic imidazolate framework-7 (Cu-doped ZIF-7) was synthesized rapidly and easily using a microwave-assisted technique. Various analytical and spectroscopic methods were employed to access the framework, morphology, light absorption, photo-electrochemical and photocatalytic performance of the synthesized materials. Compared to ZIF-7, Cu/ZIF-7 (molar ratio of Cu2+ to Zn2+ is 1:1) demonstrates superior visible light absorption ability, narrower band gap, enhanced charge separation capability, and reduced electron–hole recombination performance. Under visible light irradiation, Cu/ZIF-7 serves as a Fenton-like catalyst and demonstrates exceptional activity for contaminant degradation, while virgin ZIF-7 remains inactive. With the addition of 9.8 mmol H2O2 and exposure to visible light for 30 min, 10 mg of Cu/ZIF-7 can completely decompose RhB solution (10 mg/L, 50 mL). The synergistic effect of the Cu/ZIF-7/H2O2/visible light system is attributed to visible light photocatalysis and Fenton-like reactions. Cu/ZIF-7 demonstrates excellent catalytic performance stability, with only a slight decrease in degradation efficiency from an initial 97.0% to 95.4% over four cycles. Additionally, spin-trapping ESR measurements and active species trapping experiments revealed that h+ and ·OH occupied a significant position for Rhodamine B (RhB) degradation. Degradation intermediate products of Rhodamine B have been identified using UPLC-MS, and the degradation pathways have been proposed and discussed. This work offers a facile and efficient technique for developing MOF-based visible light photocatalysts for water purification.

Enhancing photocatalytic degradation of rhodamine B with visible-light-driven HCl-assisted Bi2O3 photocatalysts: Activity, mechanism, and pathways

This study utilized X-diffraction, BET, photoluminescence, UV–vis DRS, FTIR, SEM, XPS, TOC analysis, EPR, electrochemical measurements, and LC-MS to characterize the structural characteristics, morphology, optical properties, photocatalytic activity, surface electronic states, active compounds, and potential photodegradation pathways of rhodamine B (RhB) over as-prepared Bi2O3. The as-prepared Bi2O3 photocatalyst exhibited a narrow bandgap, which enabled efficient absorption of visible light, thereby contributing to its enhanced photocatalytic activity. Additionally, Bi2O3 exhibited a high degradation efficiency for RhB. with up to 96.8 % of RhB removed within 120 min at pH 3.0. The excellent photocatalytic performance of Bi2O3 can be attributed to the formation of the heterogeneous Bi2O3/BiOCl structure on the Bi2O3 surface in the presence of HCl. Moreover, the TOC analysis revealed that over 58.1 % of the carbon in the RhB solution was mineralized into CO2 after 120 min of irradiation. The effect of catalyst content, RhB concentration, initial pH, and inorganic anions on the photocatalytic degradation of RhB over Bi2O3 was examined. Furthermore, the active compounds and potential photocatalytic mechanism of the Bi2O3/BiOCl heterogeneous structure toward RhB were evaluated. The intermediates formed during RhB degradation were identified, and the corresponding degradation pathway was deduced via LC-MS.

Construction of Rod-Like Bi4O5I2/NaYF4:Yb,Tm Composite and its Improved Photocatalytic Degradation Performance Under Near-Infrared Light

Photocatalytic technology exhibits promising prospects in environmental remediation owing to its sustainable and environmentally friendly advantages. Among the bismuth-rich halide oxides, Bi4O5I2 has demonstrated remarkable efficacy in dye degradation due to its favorable valence band and conduction band positions. In this study, we successfully synthesized Bi4O5I2/NaYF4:Yb,Tm composites through a solvothermal method. When exposed to visible light, the Bi4O5I2/NaYF4:Yb,Tm composite achieved an impressive degradation rate of 86.7% for RhB solution after 60[Formula: see text]min of light-induced reaction. Moreover, the incorporation of NaYF4:Yb,Tm into Bi4O5I2 extended the utilization of near-infrared (NIR) spectroscopy. Under 980[Formula: see text]nm NIR light irradiation, the degradation rate of Rhodamine B (RhB) solution by the Bi4O5I2/NaYF4:Yb,Tm composite reached 43.0% after 240[Formula: see text]min of light reaction. Free radical capture experiments confirmed that h[Formula: see text] and •[Formula: see text] O[Formula: see text] played a significant role as the primary active species in the degradation process of RhB by the Bi4O5I2/NaYF4:Yb,Tm composites. Furthermore, we explored the mechanism behind the photocatalytic degradation of RhB solution using the Bi4O5I2/NaYF4:Yb,Tm composites. Bi4O5I2/NaYF4:Yb,Tm holds great potential as a promising candidate for utilization of NIR light for photocatalytic reactions.

Evaluation on photocatalytic activity of bismuth nitrate derived materials at different calcination temperatures using paper microzones method

Our work reveals for the first time that directly calcined bismuth nitrate derivatives (BNDs) possess significant photocatalytic activity towards rhodamine B (RhB). As the calcination temperature increased, the Bi(NO3)3·5H2O powder gradually ruptured and transformed into different bismuth nitrate products and their mixtures, finally into stable α-Bi2O3 at 500 °C. Among them, BNDs-100 could achieve 100 % photocatalytic degradation of 10 mg/L RhB solution under UV irradiation for 6 min. The ImageJ-led paper microzones (PMZs) method is introduced for the first time into the performance evaluation process of photocatalysts, which can achieve the green chemistry pathway and the rapid evaluation of different catalysts. The accuracy of the results of the PMZs method relative to the spectrophotometric method was up to 91.14 %, which has a better reliability and is suitable for qualitative analysis, and a certain ability when used for quantitative analysis. The results showed that the PMZs method was used to assess the photocatalytic degradation of rhodamine B by bismuth nitrate-derived materials at different calcination temperatures with well reliability, and the preparation of BNDs by direct calcination was a simple and effective strategy.

Automatic Localization of Soybean Seedlings Based on Crop Signaling and Multi-View Imaging.

Soybean is grown worldwide for its high protein and oil content. Weeds compete fiercely for resources, which affects soybean yields. Because of the progressive enhancement of weed resistance to herbicides and the quickly increasing cost of manual weeding, mechanical weed control is becoming the preferred method of weed control. Mechanical weed control finds it difficult to remove intra-row weeds due to the lack of rapid and precise weed/soybean detection and location technology. Rhodamine B (Rh-B) is a systemic crop compound that can be absorbed by soybeans which fluoresces under a specific excitation light. The purpose of this study is to combine systemic crop compounds and computer vision technology for the identification and localization of soybeans in the field. The fluorescence distribution properties of systemic crop compounds in soybeans and their effects on plant growth were explored. The fluorescence was mainly concentrated in soybean cotyledons treated with Rh-B. After a comparison of soybean seedlings treated with nine groups of rhodamine B solutions at different concentrations ranging from 0 to 1440 ppm, the soybeans treated with 180 ppm Rh-B for 24 h received the recommended dosage, resulting in significant fluorescence that did not affect crop growth. Increasing the Rh-B solutions reduced crop biomass, while prolonged treatment times reduced seed germination. The fluorescence produced lasted for 20 days, ensuring a stable signal in the early stages of growth. Additionally, a precise inter-row soybean plant location system based on a fluorescence imaging system with a 96.7% identification accuracy, determined on 300 datasets, was proposed. This article further confirms the potential of crop signaling technology to assist machines in achieving crop identification and localization in the field.

Boosting tribo-catalytic degradation of organic pollutants by BaTiO3 nanoparticles through metallic coatings

Recently, tribo-catalysis has emerged as an appealing technology to harvest mechanical energy for environmental remediation. While most investigations have focused on catalyst optimization to enhance tribo-catalytic degradation, here we studied the effects of some metal disks placed on beaker bottoms (named coatings) on the tribo-catalytic degradation by BaTiO3 (BTO) nanoparticles under magnetic stirring. For 20 mg/L Rhodamine B (RhB) solution, Cr, Cu, and Ti coatings improved the kinetic constants of BTO nanoparticles by 3.1, 3.4, 5.2 folds, respectively. Ti coating was further found to result in 99 % degradation in just 3 h for 50 mg/L RhB solution, and elevate the kinetic constants by 19.1 and 16.6 folds for 20 mg/L methyl orange (MO) and 20 mg/L methylene blue (MB) solutions, respectively. EPR, FL and UV–vis spectroscopy verified that modifying vessel bottom with Ti coating enabled BTO nanoparticles to generate more active species. First-principles calculations of the work functions of Cr, Cu, and Ti surfaces, and the energy-band structure of BTO revealed a decreased electron-hole recombination rate due to the transfer of excited electrons to metallic coatings. These results suggest that modifying vessel bottoms with suitable metallic coatings is a simple, eco-friendly and efficient strategy to boost tribo-catalysis for environmental remediation.

Fabrication of WO3-Ag3PO4 heterojunction on carbon cloth for efficient visible-light degradation of rhodamine B

The WO3-Ag3PO4 heterojunction on carbon cloth (CC@WO3-Ag3PO4) was prepared through a facile two step approach. The photocatalysts are evaluated in the degradation of rhodamine B (RhB) under visible light irradiation; CC@WO3-Ag3PO4 exhibited enhanced photocatalytic RhB efficiency. The calculated k for the degradation of RhB over CC@WO3@Ag3PO4 is 0.03097 min−1, which is higher than those for reactions over CC@Ag3PO4 (0.01254 min−1) and CC@WO3 (0.00935 min−1). The photocatalytic efficiency is significantly enhanced after formation of the CC@WO3-Ag3PO4 heterojunction. This could be mainly attributed to improved photogenerated electron-hole pairs separation ability after formation of the CC@WO3-Ag3PO4 heterojunction. Furthermore, the carbon cloth serving as support for photocatalyst can enhance the contact area of the photocatalyst with RhB solution and visible light due to its large specific surface area. Additionally, CC@WO3-Ag3PO4 photocatalyst can be quickly and completely recycled, effectively avoiding recontamination.

Synthesis and photocatalytic activity of montmorillonite/TiO2 nanocomposites for rhodamine B degradation under UVC irradiation

Abstract The increasing contamination of water by organic dyes causes water pollution in the enviroment. Factories discharge untreated effluents into nearby water courses adding to the existing water pollution; this poses a significant environmental challenge. Hence there is a pressing demand to develop efficient technology for wastewater treatment, and photocatalysis has emerged as an advanced oxidation process with a green chemical approach for such treatment. This study aims to synthesize montmorillonite/TiO2 (Mnt/TiO2) photocatalysts and clarify the effect of montmorillonite content on the photodegradation of the organic dye rhodamine B (RhB). Mnt/TiO2 was prepared by a chemical method with various mass ratios of mMnt:mTiO2 based on the cation exchange capacity (CEC) of Mnt. The physicochemical properties of the samples prepared were determined by the following methods: energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The photocatalytic degradation efficiency of the RhB solution of Mnt/TiO2 was investigated by UV-Vis spectroscopy under UVC irradiation. Liquid chromatography-mass spectrometry (LCMS) was used to identify the photocatalytic by-products. The results showed that the structure of the nanocomposites has a ‘house-of-cards’ form with TiO2 nanoparticles randomly distributed on the surface and sheets of clay minerals. The best mass ratio of mMnt:mTiO2 is 10:1, corresponding to a 10 ppm RhB solution decolorization efficiency of 91.5% in 210 min. In this study, Mnt/TiO2 successfully cleaved the dye chromophore structure and broke the RhB rings into small and broken-ring compounds.

Na2Ti3O7@RF@Ag Heterostructures as Efficient Substrates for SERS and Photocatalytic Applications.

A multi-step procedure was effectively employed to synthesize innovative three-dimensional (3D) heterostructures encompassing sodium titanate (Na2Ti3O7) nanowire cores, an intermediate resorcinol-formaldehyde (RF) layer, and outer silver (Ag) nanoparticle sheaths, referred to as Na2Ti3O7@RF@Ag heterostructures. Initially, a one-step hydrothermal technique facilitated the direct growth of single-crystal Na2Ti3O7 nanowires onto a flexible Ti foil. Subsequently, a two-step wet chemical process facilitated the sequential deposition of an RF layer and Ag nanoparticles onto the Na2Ti3O7 nanowires at a low reaction temperature. Optimal concentrations of silver nitrate and L-ascorbic acid can lead to the cultivation of Na2Ti3O7@RF@Ag heterostructures exhibiting heightened surface-enhanced Raman scattering (SERS), which is particularly beneficial for the detection of rhodamine B (RhB) molecules. This phenomenon can be ascribed to the distinctive geometry of the Na2Ti3O7@RF@Ag heterostructures, which offer an increased number of hot spots and surface-active sites, thereby showcasing notable SERS enhancement, commendable reproducibility, and enduring stability over the long term. Furthermore, the Na2Ti3O7@RF@Ag heterostructures demonstrate remarkable follow-up as first-order chemical kinetic and recyclable photocatalysts for the photodecomposition of an RhB solution under UV light irradiation. This result can be attributed to the enhanced inhibition of electron-hole pair recombination and increased surface-active sites.

Natural bamboo powder and coffee ground as low-cost green adsorbents for the removal of rhodamine B and their recycling performance

Bamboo and coffee, which are abundant and inexpensive, have been used as green adsorbents for the adsorption of industrial dye rhodamine B (RB). Bamboo and coffee are natural sources of cellulose, hemicellulose, and lignin, making them promising green materials for industrial dye removal. The effects of various adsorption conditions, such as contact time, temperature, dose of bamboo powder (BP), coffee ground (CG), initial concentration of RB, and pH values of RB solution, were measured. Consequently, the kinetics of RB adsorption onto bamboo and coffee was in accordance with the pseudo-second-order model, with an activation energy of 29.51 kJ mol−1 for bamboo and 27.46 kJ mol−1 for coffee. The Langmuir model is well fitted to the whole adsorption period at different temperatures, in which the increase in the tested temperature has improved the adsorption capacity (i.e., BP: 6.76 mg g−1/30 °C, 6.96 mg g−1/40 °C, 7.64 mg g−1/50 °C and CG: 6.53 mg g−1/30 °C, 6.80 mg g−1/40 °C, 7.51 mg g−1/50 °C). Moreover, the spontaneous nature of the adsorption was based on the negative Gibbs free energy values obtained (i.e., from − 11.09 to − 14.30 kJ mol−1 [BP] and from − 10.34 to − 13.07 kJ mol−1 [CG]). These revealed that RB adsorption occurred at physical and chemical adsorption states. In addition, the recycling capability of adsorbents was determined in five cycles. Therefore, these materials are promising candidates for low-cost adsorbents.