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In this work, solid-surface fluorescence spectra of Rhodamine B (RhB) and fluorescein (FLU), two extensively used fluorophores, were studied and their concentrations were semi-quantitatively determined using the three-dimensional excitation–emission matrix (3D-EEM) data. In order to measure the solid fluorescence spectra, a trace amount of fluorophores was physically adsorbed on a piece of filter paper as a fluorescent paper, and the fluorescence spectra were recorded from the surface of the fluorescent paper instead of the inner parts of the solution. The spectral measurement was performed utilizing a routine spectrofluorimeter designed to measure the fluorescence of solution only by placing the fluorescent paper in a simple handmade holder at an adjusted incident angle of radiation. The results revealed a significant increase in the fluorescence intensity of the fluorescent paper strip compared to the solution phase. Moreover, in the RhB–FLU paper strip the forster resonance energy transfer was observed between FLU and RhB, similar to the observed phenomenon in the solution phase. For quantifying fluorophores, the EEM data were successfully resolved by applying multivariate partial least squares and parallel factor analysis (PARAFAC) modeling, and the results were compared with the univariate method. This study may provide a general guideline in further developing the solid fluorescence measurement of concentrated solutions or solid samples that have fluorescence measurement limitations such as high self-absorption and highly scattered spectra by using a conventional spectrofluorimeter, and also of biological samples where a trace amount of the analyte is available and high sensitivity is required. [ABSTRACT FROM AUTHOR]

Fluorescent sensors with single reading are generally subject to unpredictable disturbs from environmental and artificial factors. In order to overcome this barrier of detection reliability, a paper-based optical sensor with proportional fluorescence was established and further combined with a smartphone for visual, on-site and quantitative detection of Fe3+, which affects the color, smell and taste of water, and endangers the health of plants and animals. The ratio fluorescent probe was fabricated by rhodamine B and carbon quantum dots derived from xylan. The red fluorescence of rhodamine B was inert to Fe3+, which was referred to as background. And blue emitting carbon quantum dots functioned as signal report units, which would be quenched by Fe3+ and make the fluorescence of the ratio probe change from purple to red. The quantitative detection of Fe3+ was conducted by investigating the RGB value of fluorescent images with a smartphone. With the increase of Fe3+ concentration, the R/B (red/blue) value of the fluorescent paper gradually increased. The linear detection range was 10–180 μM, and the limit of detection was 198.2 nM. The application of ratio fluorescent paper with a smartphone provides a facile method for the rapid detection of ions. [ABSTRACT FROM AUTHOR]

The surface-enhanced Raman scattering (SERS) properties of low-dimensional semiconducting MXene nanoflakes have been investigated over the last decade. Despite this fact, the relationship between the surface characteristics and SERSing performance of a MXene layer has yet to be comprehensively investigated and elucidated. This work shows the importance of surface morphology on the overall SERS effect by studying few-layer Ti3C2Tx MXene-based SERS substrates fabricated by vacuum-assisted filtration (VAF) and spray coating on filter paper. The VAF deposition results in a dense MXene layer suitable for SERS with high spot-to-spot and substrate-to-substrate reproducibility, with a significant limit of detection (LoD) of 20 nM for Rhodamine B analyte. The spray-coated MXenes film revealed lower uniformity, with a LoD of 50 nM for drop-casted analytes. Moreover, we concluded that the distribution of the analyte deposited onto the MXene layer is affected by the presence of MXene aggregates created during the deposition of the MXene layer. Accumulation of the analyte molecules in the vicinity of MXene aggregates was observed for drop-casted deposition of the analyte, which affects the resulting SERS enhancement. Ti3C2Tx MXene layers deposited on filter paper by VAF offer great potential as a cost-effective, easy-to-manufacture, yet robust, platform for sensing applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Directly calcined bismuth nitrate derivatives possess significant photocatalytic activity. • ImageJ-led paper microzones method for the first time into the performance evaluation process of photocatalysts. • The accuracy of the results of the PMZs method relative to the spectrophotometric method was up to 91.14%. 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(NO 3) 3 ·5H 2 O powder gradually ruptured and transformed into different bismuth nitrate products and their mixtures, finally into stable α-Bi 2 O 3 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. [ABSTRACT FROM AUTHOR]

A novel platform of a polydiacetylene combined with rhodamine B (PDA-Rho) colorimetric chemosensor array was prepared from a diacetylene monomer and rhodamine B derivative. Rhodamine B derivative as the ion-recognition element was embedded in the polydiacetylene matrix. To fabricate chemosensor, diacetylene monomer connected rhodamine B derivatives (DA-Rho) was coated onto a filter paper surface via drop-casting technique and transformed to polydiacetylene by polymerisation through ultraviolet (UV) irradiation. From the result, PDA-Rhoen exhibited high sensitivity and selectivity for Au3+ and could be monitored directly by naked eyes providing a fast, portable and easy-to-use as a molecular device in the real system. The DFT calculation results showed a stable complex between PDA-Rho and Au3+. We believe that, this method offers a sensitive and accurate process for Au3+ ion detection in real environmental and biological applications. [ABSTRACT FROM AUTHOR]

The textile industry is one of the most important industries in the European Union. The main environmental problems of the textile industry are the high water consumption, the generated pollution, the variety of chemicals used and the high energy demand. Recently, adsorbents with a large specific surface area and low weight, such as aerogels, have attracted great interest as promising materials for removing dyes from polluted water. Cellulose aerogels are inexpensive and non-toxic. Langmuir and Freundlich isotherms were chosen as the best method to describe the performance of the adsorbent. In this study, the adsorption efficiency of Congo red, Naphthol green B, Rhodamine B and Methylene blue were determined by using an adsorbent synthesized from paper and cardboard waste. The total organic carbon concentration was chosen as an indicator of the concentration of the dyes in the solutions. The aerogel capsules had 5% cellulose content. It was found that the adsorption capacity of the aerogel in the solutions of Congo red varied from 0.028 mg/g to 14.483 mg/g; in the solutions of Naphthol green B, from 0.013 mg/g to 7.698 mg/g; in the solutions of Rhodamine B, from 0.020 mg/g to 8.768 mg/g; and in the solutions of Methylene blue, from 0.024 mg/g to 13.538 mg/g. [ABSTRACT FROM AUTHOR]

The surface-enhanced Raman scattering (SERS) properties of low-dimensional semiconducting MXene nanoflakes have been investigated over the last decade. Despite this fact, the relationship between the surface characteristics and SERSing performance of a MXene layer has yet to be comprehensively investigated and elucidated. This work shows the importance of surface morphology on the overall SERS effect by studying few-layer Ti3C2Tx MXene-based SERS substrates fabricated by vacuum-assisted filtration (VAF) and spray coating on filter paper. The VAF deposition results in a dense MXene layer suitable for SERS with high spot-to-spot and substrate-to-substrate reproducibility, with a significant limit of detection (LoD) of 20 nM for Rhodamine B analyte. The spray-coated MXenes film revealed lower uniformity, with a LoD of 50 nM for drop-casted analytes. Moreover, we concluded that the distribution of the analyte deposited onto the MXene layer is affected by the presence of MXene aggregates created during the deposition of the MXene layer. Accumulation of the analyte molecules in the vicinity of MXene aggregates was observed for drop-casted deposition of the analyte, which affects the resulting SERS enhancement. Ti3C2Tx MXene layers deposited on filter paper by VAF offer great potential as a cost-effective, easy-to-manufacture, yet robust, platform for sensing applications.

A novel colorimetric-fluorescent dual-mode sensing sensor JT5 was successfully synthesized, and exhibited red fluorescence enhancement effect and red colorimetric sensing, and excellent applicability through solid-state fluorescent strips and biological imaging experiments on zebrafish to highly sensitive monitoring Sn4+ ions. [Display omitted] • A novel and effective rhdamine B-based sensor JT5 successful development. • JT5 can serve as a fluorescent and colorimetric on-off sensor for Sn4+. • The sensor JT5 was successfully studied using fluorescence and colorimetric of the test strips. • Biomaging experiments for the sensor JT5 were conducted on zebrafish using a confocal microscope. A novel colorimetric-fluorescent dual-mode chemosensor (JT5) based on rhodamine B has been produced for monitoring Sn4+ in the DMSO/H 2 O (4:1, v/v) medium. It has high sensitivity, a low detection limit, a short response time (1 s) and high stability, and can still be maintained after two weeks with the red dual fluorescence/ colorimetric response. Enhancement of red fluorescence (591 nm) and red colorimetric (567 nm) response of JT5 by Sn4+ addition. The electrostatic potential of the sensor JT5 molecule was simulated to speculate on the sensing mechanism, and the IR, mass spectrometry and 1H NMR titration were utilized to further demonstrate that JT5 was coordinated to Sn4+ with a 1:1 type, the rhodamine spironolactam ring of JT5 opens up to form a penta-membered ring with Sn4+, meanwhile, its system may have chelation enhanced fluorescence (CHEF) effect. In addition, theoretical calculations were carried out to give the energy gaps of JT5 and [ JT5 + Sn4+] as well as to simulate the electronic properties of the maximal absorption peaks. Notably, the sensor JT5 was successfully applied to monitoring Sn4+ in zebrafish, and the JT5 -loaded filter paper provided a solid-state platform for detecting Sn4+ by both naked eye and fluorescent methods. In summary, this work contributes to monitoring Sn4+ in organisms and solid-state materials and promotes understanding of Sn4+ functions in biological systems, environments, and solid-state materials. [ABSTRACT FROM AUTHOR]

The crystal violet (CV) staining technique represents a prevalent approach for the development of latent fingerprints, especially on adhesive tape surfaces. Nevertheless, the technique necessitates intricate formulations to augment its performance. In this investigation, an optimized CV staining protocol was developed, characterized by the absence of residual dye on the target substrates and the capability of facilitating fingerprint visualization under ambient light conditions. Four donors, comprising two males and two females, deposited natural fingerprints on various substrates, including glass microscope slides, aluminum foil, and 115 g glossy coated paper, without any specific guidelines. Fingerprints developed using cyanoacrylate fuming served as benchmarks and were contrasted with those generated through alternative methods: CV, ardrox, rhodamine 6G, powdering, and the optimized CV staining protocol. The fingerprint development experiment was replicated at seven distinct time intervals, encompassing 1 day, 1 week, 1, 3, 6, 9, and 12 months, resulting in a dataset of 420 fingerprints. The evaluation of fingerprint identifiability employed a scoring system established by the Home Office Centre for Applied Science and Technology. The results indicated that the optimized CV staining technique demonstrated superior performance, boasting a 92.9% rate of identifiable fingerprint development in contrast to other employed methodologies. Consequently, this optimized CV staining approach is recommended as an efficient, rapid, and straightforward critical dyeing method, applicable to a wide array of substrates in forensic investigations. [ABSTRACT FROM AUTHOR]

The following research paper concerns the analysis and characterisation of commercially available surface-enhanced Raman scattering (SERS) substrates. SERS has long been a potentially very powerful method with a great deal of interest around it; however, there are still many obstacles which do not allow SERS to be easily applied to real-world detection and analysis problems. As such, research around the various types of substrates is ongoing, in the hope of streamlining and improving the Raman enhancement mechanism. Scanning electron microscope images were obtained for each of the three substrates, and their features and scales were described. Enhanced Raman spectra for Rhodamine B were obtained for a range of concentrations using each of the three substrates, and, in addition, surface enhancement maps are presented. Enhancement factors were calculated for the 1358 cm−1 peak of Rhodamine B. Complementing the experimental work, theoretical FEM modelling in COMSOL Multiphysics was performed, with the resulting calculations yielding an enhancement prediction adequately accurate to the real substrates. [ABSTRACT FROM AUTHOR]

This research paper delves into the enhancement of wastewater treatment through the design and synthesis of advanced photocatalytic materials, focusing on the effects of sodium (Na) substitution in Ca1‐xNaxTa0.5Ti0.5O3 perovskites. By employing various analytical techniques such as X‐ray diffraction, Field Emission Scanning Electron Microscopy, Transmission Electron Microscopy and UV‐vis spectroscopy, the study examines the transition of these perovskites from tetragonal to orthorhombic structures and observes a reduction in Ca content with Na substitution, which also favors the cubic phase formation and inhibits secondary phases. Significantly, magnetic property analysis uncovers an unexpected ferromagnetic ordering in these perovskites, including compositions traditionally viewed as non‐magnetic. The photocatalytic tests reveal a significant improvement in degrading Rhodamine B dye under visible light, particularly in samples with higher Na levels, attributed to enhanced light absorption and efficient electron processes. The study highlights the optimal Na substitution level for peak photocatalytic performance, offering valuable insights into the complex interplay between structural, magnetic, and photocatalytic properties of these perovskites, and their potential in various applications, thereby contributing to the advancement of wastewater treatment technologies. [ABSTRACT FROM AUTHOR]

Copper and Mercury ions have vital role to play in biological world as their excess or deficiency can cause different type of diseases in human being as well as biological species including plants and animals. Therefore, their detection at trace level becomes very important in term of biological. The current studies embody the fabrication, structural characterization and recognition behavior of a novel rhodamine B hydrazone formed when hydrazide of rhodamine B was condensed with 5-Allyl-3-methoxy salicylaldehyde (RBMA). RBMA was found to be responsive towards the very trace level of Cu2+ and Hg2+ among other tested cations so far. The sensing procedure is based on the classical opening of the spiroatom ring of rhodamine. The limit of detection (LOD) and binding constant is 5.35 ppm, 2.06 × 104 M−1 and 5.16 ppm, 1.26 × 104 M−1 for Cu2+ and Hg2+ ions respectively. The probable mechanism correlates the specific binding of RBMA with Cu2+ and Hg2+ ions. The 1:1 stoichiometry of RBMA with Cu2+ and Hg2+ ions have been supported by HRMS, FT-IR data, Job's plot, and binding constant data. Reversibility is well exhibited by RBMA by the involvement of CO32− ions via demetallation process. The real time application is well demonstrated by the use of paper strip test. The DFT study also carried out which agrees well with the experimental findings. The results displayed the novelty of this current work towards the trace level analysis of the Cu2+ and Hg2+ of the cations which are play the crucial role in industry. [ABSTRACT FROM AUTHOR]

In this paper, the novel PCN-224/cloisite-30B composite is prepared through the solvothermal method. Cloisite-30B, a natural, nonpoisonous, and inexpensive substance, has been composited with porphyrinic-based-MOF for the first time. The mentioned composite has been characterized by X-ray diffraction analysis, Fourier-transform infrared spectroscopy, thermogravimetric analysis, Brunauer–Emmett–Teller analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Also, the quadratic model for predicting methylene blue (MB) removal efficiency is presented (R2 = 0.9984, R2adj = 0.9954). Moreover, the optimum condition for MB adsorption has been assessed through Design-Expert software (80 initial dye concentration, 20 mg adsorbent, 30 min adsorption time, pH = 7). At the optimum condition, the adsorption capacity of adsorbent toward four other dyes has been studied, including methyl orange (MO), rhodamine B (RhB), congo red (CR), and eriochrome black T (EBT). The adsorption (Langmuir, Freundlich, and Temkin model) and kinetic (first and second order) study were calculated based on non-linear equations. PCN-224/cloisite-30B is an efficient adsorbent in dye removal and acts selectively when it is in contact with anionic and cationic species with close molecular size. Furthermore, the composite is highly recyclable, after ten washing cycles, it has the same efficiency as the first cycle in MB removal. [ABSTRACT FROM AUTHOR]

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This paper introduces an in-line dye tracer experiment to measure the residence time functions in continuous concrete processing. These functions quantify the material-system interdependency and can be used to compare different material-system combinations and for quality and process control. A Rhodamine B solution was used as the tracer material and detected by measuring the color intensity using a digital image processing technique. The experiment was validated on a 3D concrete printing system by comparing the results of impulse, step-up and step-down inputs with different tracer quantities. The results show that a high signal-to-noise ratio can be obtained with low tracer concentrations. For the examined combination of material and system, an impact on the original process was only observed for the step-up inputs at high tracer quantities. It is concluded that the presented method is cost-effective and non-labor-intensive and, therefore, has the potential for wide adoption and integration in automated workflows. [ABSTRACT FROM AUTHOR]

Magnetic separation of photocatalysts holds great promise for water treatment. A magnetic separation method has a positive effect on the recovery of catalysts after degradation. In this paper, an efficient and reusable catalytic system is developed based on coating magnetic Fe3O4 by depositing Fe2+ on the surface of ZnO. The Fe3O4/ZnO nanocomposite exhibits enhanced performance for organic pollutant degradation. The Fe3O4/ZnO system demonstrates a high photocatalytic activity of 100% degradation efficiency in Rhodamine B (RhB) degradation under UV light irradiation for 50 min. The excellent photocatalytic activity is primarily due to the separation of photogenerated electron-hole pairs being facilitated by the strong interaction between Fe3O4 and ZnO. The induction of the magnetic Fe3O4 endows the Fe3O4/ZnO composite with superior magnetic separation capability from water. Experiments with different radical scavengers revealed that the hydroxyl radical (·OH) is the key reactive radical for the effective degradation of RhB. This work innovatively affords a common interfacial dopant deposition strategy for catalytic application in the degradation of organic dye pollutants and catalyst separation from wastewater efficiently. [ABSTRACT FROM AUTHOR]

[Display omitted] • Recyclable silver immobilized chitosan/carboxy methyl chitosan macromolecules as visible light-responsive photocatalyst. • Structural tailoring morphological studies was scrutinized using advanced techniques. • Highly efficient photocatalytic degradation of methyl orange (MO) and rhodamine B (RB) dyes from wastewater. • Optimization of degradation using response surface methodology (RSM). This study explores the potential of modified chitosan (CH) resulting from carboxy methyl (CM) group substitution in the chitosan skeleton, producing carboxy methyl chitosan (CMCH). Silver (Ag) was loaded to chitosan and modified chitosan (carboxy methyl substituted chitosan) supported on cellulose filter paper (FP) to tailor organic–inorganic macromolecule composites "Ag-Chi/CFP and Ag-CMCH/CFP" further applied as substantial composite for the reductive removal of methyl orange (MO) and rhodamine B (RB) dyes from wastewater. The synthesized catalyst was characterized via FTIR, 1H NMR, XRD, and SEM analysis. The degree of substitution was also measured, which was approximately 0.85. The reductive elimination efficiency of Ag-CMCH/CFP and Ag-Chi/CFP for MO dye was 95.31% and 88.85 %. In comparison, the elimination of RB was 98.28 and 94.04 %, respectively, in 16 min time, 0.6 mM Ag concentration, 40 mg/L, dye concentration and 0.3 M NaBH 4 concentration. The synthesized catalysts were recycled three times. The degradation of MO and RB dyes using Ag-CMCH/CFP and Ag-Chi/CFP catalysts can be described by the first-order kinetic model. The determination coefficients (R2) and rate constants (k) values for MO degradation were found to be 0.9934 and 0.1736 s−1 for Ag-CMCH/CFP, and 0.9242 and 0.1001 s−1 for Ag-Chi/CFP, respectively. Similarly, for RB degradation, the R2 values were 0.9866 for Ag-CMCH/CFP and 0.9803 for Ag-Chi/CFP, with corresponding k values of 0.219 s−1 and 0.1548 s−1, respectively. The degradation process was optimized using response surface methodology (RSM) to determine the optimal conditions for maximum dye removal efficiency. The RSM models were statistically significant, as validated by ANOVA and correlation coefficient values. The F values of MO and RB models are significant as they have 2450.15 and 21999.37, respectively. The P value for both was <0.0001. [ABSTRACT FROM AUTHOR]

In this paper, La-doped Ti/SnO2-Sb2O4 electrode was prepared by electrodeposition and used for electrochemical degradation of rhodamine B. The optimum preparation conditions of the electrode were optimized as deposition time of 15 min and calcination at 500 ℃ for 2 h. The water treatment conditions were selected as initial pH 3.0, electrolyte Na2SO4 concentration 0.1 M, current density 30 mA cm−2, and initial rhodamine B concentration 20 mg L−1; the color and TOC removal of RhB reached 99.78% and 82.41% within 30 min. The FESEM, XRD, XPS, CV, LSV, and EIS characterization studies demonstrated that Ti/SnO2-Sb2O4-1%La electrode had a dense structure and the highest oxygen evolution potential (2.14 V) and lowest charge transfer resistance (0.198 Ω cm−2), indicating that doped La has lower energy consumption. Moreover, La doping can expand the specific surface area, active site, performance of pollutant degradation, and service life of the electrode. Especially, the service life of Ti/SnO2-Sb2O4-1%La is increased by three times, and the maximum life span reaches 90 min (1000 mA cm−2, 1 M H2SO4). Free radical quenching experiments show that ·OH plays a major role in the degradation of RhB. The Ti/SnO2-Sb2O4-1%La electrode prepared in this paper and its results will provide data support and reference for the design of efficient electrocatalytic electrode. [ABSTRACT FROM AUTHOR]

Phosphorus, an essential rare element in aquatic ecosystems, plays a key role in maintaining ecosystem balance. However, excess phosphorus leads to eutrophication and algal proliferation. To prevent eutrophication, the pretreatment and measuring of the concentration of total phosphorus (TP) is crucial. Compared to conventional TP pretreatment equipment (autoclave), a lab-on-a-chip detection device fabricated using micro-electromechanical system technology and titania (TiO2) as a photocatalyst is more convenient, efficient, and cost-effective. However, the wide bandgap of TiO2 (3.2 eV) limits photocatalytic activity. To address this problem, this paper describes the preparation of a TiO2/Au nanocomposite film using electron-beam evaporation and atomic-layer deposition, based on the introduction of gold film and TiO2 to a quartz substrate. The photocatalytic degradation properties of TiO2/Au nanocomposite films with thicknesses of 1, 2, 3, and 4 nm were assessed using rhodamine B as a pollutant. The experimental results demonstrate that the deposition of gold films with different thicknesses can enhance photocatalytic degradation efficiency through synergetic reactions in the charge separation process on the surface. The optimal photocatalytic efficiency is achieved when the deposition thickness is 2 nm, and it decreases with further increase in the thickness. When the photocatalytic reaction time is 15 min, the lab-on-a-chip (LOC) device with a 2-nm-thick gold layer and autoclave exhibits a similar TP pretreatment performance. Therefore, the proposed LOC device based on photocatalytic technology can address the limitations of conventional autoclave equipment, such as large volumes, long processing times, and high costs, thereby satisfying the growing demand for on-site evaluation. [ABSTRACT FROM AUTHOR]

In order to improve the hydrophobicity of the composite film on the wood surface, the wettability of the wood surface and its morphology, chemical structure, roughness and free energy changes were investigated in this paper after modification treatments with different volume fractions of octadecyltrichlorosilane (OTS) and polydimethylsiloxane (PDMS). It can be found that the water contact angle and surface roughness of the hydrophobically modified wood increased with the increase in volume fraction, but the overall effect of OTS hydrophobic modification was better than that of PDMS, and a maximum water contact angle of up to 140.8° could be obtained at a volume fraction of 2% of OTS. In addition, the intensity of the stretching vibration peak of -OH was weakened after the modification, while the intensity of the stretching vibration peak of -CH2- was enhanced, resulting in an increase in hydrophobicity. At the same time, it can be found that the surface free energy of the modified wood specimens was reduced, which shows that OTS and PDMS improve the surface hydrophobicity of the wood by increasing the surface roughness and decreasing the surface free energy together. Finally, the hydrophobically modified Bi2O3-doped silica–titanium composite film still possessed high photocatalytic degradation activity for rhodamine B and gas formaldehyde, and the degradation rate could reach more than 90%. [ABSTRACT FROM AUTHOR]

In this paper, coal gangue, a solid waste is used as raw material to provide silicon and aluminum sources for synthesis of zeolite. A coal gangue zeolite based Cu/Fe–X catalyst is successfully prepared by immersion-calcination method, which is used to remove Rhodamine B from aqueous solution. The characterization results show that Cu and Fe have been successfully loaded on zeolite, not damaged its structure, and these nanoparticles are highly dispersed and low crystallinity. This special structure will enhance its catalytic ability to activate H2O2. The experiment showed that hydroxyl radical (·OH) was the main active species for catalytic degradation of Rhodamine B, and the circulation of Cu2+ to Cu1+ and Fe3+ to Fe2+ could synergistically produce ·OH. Furthermore, the redox potential of Cu1+ and Cu2+ is lower than Fe2+ and Fe3+, which can promote Fe3+ circulate to Fe2+, further promote Fe2+ to activate H2O2 to decompose into ·OH, and overcome the speed limiting step of Fenton-Like catalytic reaction. The Cu/Fe–X catalyst can activate H2O2 in wide pH range (1–10). Under optimal conditions, the catalytic degradation rate can reach 99.9%, and the TOC removal rate is as high as 98.5%. Therefore, Cu/Fe–X/H2O2 system can effectively remove organic dyes, and has a high industrial application prospect. [ABSTRACT FROM AUTHOR]

The construction of a heterojunction by coupling two semiconductor photocatalysts with appropriate band positions can effectively reduce the recombination of photogenerated charge carriers, thus improving their catalytic efficiency. Recently, ZnO photocatalysts have been highly sought after in the synthesis of semiconductor heterostructures due to their wide band gap and low conduction band position. Particularly, transition metal-doped ZnO nanoparticles are attractive due to the additional charge separation caused by temporary electron trapping by the dopant ions as well as the improved absorption of visible light. In this paper, we compare the effect of doping ZnO nanoparticles with 3d (Co and Mn) and 4d (Ag) transition metals on the structural and optical properties of ZnO/CdZnS heterostructures and their photocatalytic performance. With the help of scanning electron microscopy, the successful anchoring of doped and undoped ZnO nanoparticles onto CdZnS nanostructures was confirmed. Among the different heterostructures, Ag-doped ZnO/CdZnS exhibited the best visible-light-driven degradation of rhodamine B at a rate of 1.0 × 10−2 min−1. The photocurrent density analysis showed that AgZnO/CdZnS has the highest amount of photogenerated charges, leading to the highest photocatalytic performance. The reduction in the photocatalytic performance in the presence of hole scavengers and hydroxyl radical scavengers confirmed that the availability of photogenerated electrons and holes plays a pivotal role in the degradation of rhodamine B. [ABSTRACT FROM AUTHOR]

• A series of fluorescent probes based on rhodamines B and 6G with tethered sulfur-containing amines and α-amino acids were systematically investigated for Hg2+. • The optimal probe Rho6G-6 containing an L-α- S -methylcysteine methyl ester residue was capable of sensitively (detection limit = 8 nM) and selectively recognizing Hg2+. • The formation of a stoichiometric 1:2 probe:Hg2+ complex was demonstrated to investigate the sensing mechanism. • Test paper strip, live cell and mice imaging applications were performed for Rho6G-6 in presence of Hg2+. Inspired by the suitability of rhodamine spirolactam switching for superresolution imaging and fluorescent probe development, we herein synthesized rhodamine-based probes with sulfur-bearing amine and amino acid moieties and screened their abilities to respond to Hg2+ in the presence of other metal ions. The probe based on S -methylcysteine methyl ester–substituted rhodamine 6G (Rho6G-6) was identified as optimal because of its straightforward synthesis and rapid, selective, and sensitive (detection limit = 8 × 10–9 M) response to Hg2+ manifested by absorption spectrum and emission color changes. The complexation of Hg2+ by Rho6G-6 was examined by absorbance and fluorescence analyses, electrospray ionization–mass spectrometry, and 1H nuclear magnetic resonance (NMR) titration experiments. Furthermore, the practical applicability of the above probe was demonstrated by naked-eye colorimetric Hg2+ detection using paper test strips and the fluorescence-based qualitative mapping of the Hg2+ distribution in living HeLa cells and the organs of live mice. Thus, unlike other probe design strategies, the use of flexible S -methyl amino acids for Hg2+ binding provides new opportunities and strategies for photopromoting the ring switching of the rhodamine spirothiolactam. [ABSTRACT FROM AUTHOR]

Surfactant‐assisted synthesis of photocatalysts for water treatment has received extensive attention from researchers. In this paper, a novel and efficient BiOBr/graphene oxide (BiOBr/GO) photocatalyst assisted by sodium dodecyl sulfate (SDS) was synthesized by a simple solvothermal method. Compared with use of other surfactants, like polyvinylpyrrolidone (PVP) and cetyltrimethylammonium bromide (CTAB), BiOBr/GO (SDS) shows outstanding photocatalytic degradation activity under optimal conditions: The degradation rate constants of BiOBr/GO (SDS) for oxytetracycline (OTC), tetracycline hydrochloride (TCH), brilliant blue (BB), and Rhodamine B (RhB) are 0.073, 0.057, 0.166, and 0.626 min−1, which are 2.8, 1.8, 9, and 1.5 times larger than pure BiOBr, respectively. In addition, after five cycles, BiOBr/GO (SDS) exhibits superior cycling stability. The enhanced photocatalytic performance can benefit from the introduction of SDS and GO. With the assistance of SDS in the preparation process, BiOBr/GO (SDS) nanosheets have good adsorption performance and dispersion effect, which is favorable for raising their specific surface area. Meanwhile, the electron capture effect of GO improves the transfer and separation efficiency of photogenerated carriers. Moreover, the possible degradation pathway for TCH is identified through liquid chromatography–mass spectrometry (LC–MS). This research can become a valuable reference for synthesizing photocatalysts with visible light response to degrading organic pollutants such as antibiotics and dyes. [ABSTRACT FROM AUTHOR]

The availability of fresh water is limited compared to its huge consumption. Conversely, certain industries like dyes, textiles, paper, and tanning not only consume vast quantities of fresh water, but also generate significant amounts of wastewater that poses severe threats to living organisms. The present investigation focuses on the degradation of Rhodamine-B (Rh–B) as a model pollutant by using the nanocomposite based on waste scrap tire-derived activated carbon (AC) and titanium dioxide (TiO 2). These nanostructures were fabricated using wet chemistry techniques. Analysis using scanning electron microscopy (SEM) revealed that the morphology of the structures remained largely unchanged even with a concentration of 6 mg of AC. X-ray diffraction (XRD) results confirmed the successful fabrication of rutile and anatase phases of TiO 2 @AC nanocomposite. The XPS results confirmed the presence of AC and TiO 2 in the composite. Furthermore, the optical band gap of the nanocomposites decreased up to 17.17 % and 34.57 % through direct and indirect methods respectively, owing to the varying quantity of AC used. The narrowing of optical band gap and the increased surface oxygen vacancies were caused by the successive addition of AC during the synthesis of nanocomposites. This resulted in the efficient degradation of Rhodamine-B (Rh–B) using adsorption and photocatalytic oxidation. The findings demonstrate a significant influence of AC on the TiO 2 catalyst in the removal of Rh–B dye. The maximum efficiency of dye removal, reaching up to 99.14 %, was achieved with the highest concentration of AC, thus demonstrating almost complete elimination of Rh–B dye. The findings suggest that the use of waste scrap tires can be effectively applied to design efficient photocatalysts for addressing the wastewater management issues. [ABSTRACT FROM AUTHOR]

A series of inorganic acid post-treated carbon nitride was synthesized to regulate the electronic structure, surface properties and then improve the photocatalytic activity. Carbon nitride displayed a thinner and smaller nanosheet structure after acid post-treatment, which could provide more exposed active sites and improve the charge carrier separation. The electronic band gap structure revealed that the phosphoric acid-treated sample (HP-CN) had a more positive valence band edge, endowing it with a higher oxidation ability. Furthermore, electron spin resonance (EPR) and transient photoinduced voltage (TPV) analyses demonstrated that the acid-treated carbon nitride had a higher electron–hole pair separation and transfer efficiency, thus boosting the photocatalytic performance. HP-CN possessed an optimal removal efficiency of 87.7% towards Reactive Brilliant Red X-3B (RBR X-3B), which was 1.62 times that of g-C3N4. Moreover, HP-CN showed an outstanding stability and satisfactory ability to remove RhB (rhodamine B) and TC (tetracycline), proving its potential application in environmental remediation. The photocatalytic mechanism measurement indicated that photogenerated h+, ˙O2− and ˙OH played critical roles during photocatalytic RBR X-3B decomposition. [ABSTRACT FROM AUTHOR]

BiOCl has garnered considerable attention recently. However, its relatively wide bandgap and poor separation efficiency of charge carriers limit its application in the visible light range. Introducing oxygen vacancies (OVs) and constructing heterojunctions are both considered as viable modification approaches. In this study, oxygen vacancy-rich BiOCl/Bi24O31Cl10 heterojunctions were synthesized using glycine as the fuel by a one-pot self-propagation method. Variations in the amount of fuel led to differences in OV concentration and heterojunction composition in the prepared samples. The XRD pattern, FTIR spectra and EDS confirmed the formation of BiOCl/Bi24O31Cl10 heterojunctions. The XPS and ESR spectra proved the existence of oxygen vacancies. The BET results showed that the sample prepared with an appropriate amount of glycine exhibited a larger specific surface area. The most effective OVs-BiOCl/Bi24O31Cl10 composite demonstrated improvements in degrading rhodamine B (RhB), showing 8.09 and 17.96 times greater efficiency compared to BiOCl and Bi24O31Cl10, respectively. It achieved 93% dye degradation within 30 minutes. [ABSTRACT FROM AUTHOR]

Advanced oxysulfur radical-based advanced oxidation processes (OSR-AOPs) usually use heterogeneous catalysts to activate sulfite to degrade organic pollutants in water. In this study, we report the mechanism of sulfite activation by amorphous Fe1−xNixS to degrade rhodamine B (RhB) in different pH ranges. Compared with FeS, Fe1−xNixS had a wide pH application range and high activity. For Fe1−xNixS, Ni-doping sped up electron transfer inside the catalyst and the reduced S2− promoted the ≡Fe(III)/≡Fe(II) cycle, which together improved the sulfite activation by Fe1−xNixS. The results indicated a pH dependence of RhB degradation in the Fe1−xNixS/sulfite system. The free radical pathway of SO3˙−, SO5˙− and ˙OH generated in the process was dominant under acidic condition, whereas it was mainly a non-free radical pathway of electron transfer between the catalyst and the pollutant under alkaline conditions. Both free radical and non-free radical pathways existed in Fe1−xNixS/sulfite under neutral conditions. The results shed significant light on promoting sulfite-based AOPs to remove pollutants from water. [ABSTRACT FROM AUTHOR]

Abstract\nNovelty statementThis study was aimed at evaluating the removal of different cationic dyes onto phosphoric acid-activated coconut shell carbon. The activated carbon was characterized for surface functional groups, thermal decomposition profiles, surface morphology, and textural properties. The specific area was recorded as 1,221 m2/g with 100% mesoporosity. On molecular basis, the activated carbon adsorbs malachite green, methylene blue, and rhodamine B at maximum capacities of 1.52 mmol/g, 0.80 mmol/g, and 0.58 mmol/g, respectively. It indirectly implies the selectivity of activated carbon toward malachite green, and behaves differently due to steric hindrance of dye molecules. All equilibrium data obeyed Langmuir model, while the kinetic data are closely fitted to pseudo-second order model as concentration increases. To conclude, coconut shell activated carbon is more effective to remove malachite green compared to methylene blue and rhodamine B.This paper is expected to give a further insight into the valorization of coconut shell into activated carbon, and its re-purpose for the remediation of dye-contaminated streams, for which methylene blue, malachite green and rhodamine B were used as model pollutants. This study aims to contribute to the growing body of research on the selective removal of malachite green over the other two dyes onto coconut shell activated carbon, which to the best of our knowledge is still absent in the open literature. [ABSTRACT FROM AUTHOR]

Continuous mode of adsorption using fixed bed column has been widely applied for wastewater treatment. Several dynamic mathematical models were used to analyze the adsorptive properties and breakthrough curve of the column system. This paper aims to highlight the underlying principles and applicability of three commonly used dynamic models, namely Thomas, Bohart-Adams and Yoon Nelson in estimating the behavior of continuous adsorption and its properties. The model equations were analyzed to unlock the root of derivation, and the findings from literature were summarized, compared and discussed. As opposed to the results from literature, it was revealed that the models studied are actually identical with direct relationships among the rate constants; hence, they must provide the same fitting regression. Three dynamic models were applied in a case study on column adsorption of rhodamine B by palm kernel shell activated carbon (surface area = 1775 m2/g), from which the results were presented and discussed by the analysis of breakthrough and fitting of dynamic models. The breakthrough time decreased with increasing initial dye concentration and flow rate, and vice-versa for bed height. The applicability of these dynamic models was demonstrated by the close agreement of qo from the models (33.9 mg/g − 69.3 mg/g) with the experimental ones (36.8 mg/g − 70.9 mg/g) with low percentage error. [ABSTRACT FROM AUTHOR]

The paper examines the xanthene fluorescent dyes questions available to a wide laboratories range in order to detect microplastics with an average particle length of 157 ± 59 μm in soil samples and conduct phytotests using fluorescently labeled microplastics. For the research, soils with a humus content of 1.59 ± 0.15 % (P1) and 6.74 ± 0.11 % (P2) as well as suspension polyvinyl chloride (RusVinyl LLC, 157 ± 59 μm, white) were used. In order to study the possibility of selective staining of microplastics in the presence of soil particles, polyvinyl chloride microparticles, soil P1 and P2, as well as a mixture of soil P1 and polyvinyl chloride (5 % by weight) were stained with rhodamine B, rhodamine G, fluorescein and eosin Y in isopropyl alcohol (dye concentration — 200 mg/L, temperature — 100 °C, staining time — 2 hours with constant stirring on a magnetic stirrer) and washed with distilled water on a paper filter. To study the chemical polyvinyl chloride microparticles structure before and after staining attenuated total reflectance-Fourier transform infrared spectroscopy was used (spectrometer Tensor 37 (Bruker, Germany), attenuated total internal reflection MIRacle Pike attachment with a diamond-coated ZnSe crystal). Spectrophotometry and microphotograph analysis using ImageJ software were used to determine whether dye could be leached from polyvinyl chloride microparticles after repeated washing with water. To conduct the laboratory experiment to detect microplastics in soil a mixture of P1 soil and polyvinyl chloride microparticles (0.1 % by weight) was prepared and stained with rhodamine G. In order to reduce the amount of mineral particles and concentrate polyvinyl chloride microparticles, a separation technique was used due to the difference in density using binary solution of NaCl and Ca(NO3)2. Microphotographs were obtained using an optical microscope with an additional ultraviolet source (λ = 365 nm). Image areas measurements of detected microparticles projections, that are necessary for calculating the approximate mass of the pollutant, were carried out using ImageJ software. The possibility of using fluorescently labeled polyvinyl chloride microparticles for phytotests was established using the seed germination test in contaminated soil and studying seedlings using an optical microscope with an additional ultraviolet source. It was shown that after staining with rhodamine B and rhodamine G, fluorescence is observed in polyvinyl chloride microparticles both separately and in a mixture, since soil particles P1 and P2 do not acquire similar properties. When fluorescein and eosin were used, polyvinyl chloride microparticles and soil practically did not fluoresce. It has been established that coloring does not affect the polyvinyl chloride chemical structure. Dyes are not washed out of polyvinyl chloride microparticles after repeated washing with water. The laboratory experiment showed that it is possible to detect and quantitation polyvinyl chloride microparticles in soil at the 0.1 % concentration by weight with a relative error of about 30 %. It is possible to use fluorescently labeled polyvinyl chloride microparticles with rhodamine B and rhodamine G when conducting phytotests. This research demonstrates for the first time the possibility of selective staining of polyvinyl chloride microparticles with rhodamine B and rhodamine G in a mixture with soil due to the observed fluorescence and their detection in a concentration of 0.1 % by weight. The results obtained expand knowledge in the field of monitoring microplastics in soil and, since today there are no standardized methods for detecting this pollutant, it can be used in their development. Fluorescently labeled polyvinyl chloride microparticles with rhodamine B and rhodamine G are planned to be used in phytotests as part of experiments on the hygienic justification of the maximum permissible concentration of the pollutant in the soil.

Effective adsorption of dye pollutants is essential to preserving human health and life before they are released into the environment. Ionic coordination polymers are considered good candidates for the effective elimination of dye pollutants. In this research, an anionic coordination polymer, {[NH2(CH3)2]2[Cd(μ4-L)]·1.5H2O·0.75DMF}n (1), [L4−: (E)-5,5′-(fumaroylbis(azanediyl))diisophthalate], was prepared and characterized. Structural analysis revealed that each Cd(II) ion was linked to four L4− ligands forming a 3D framework. A 2-fold interpenetrated 3D architecture of the compound was observed with a dia topology due to the large pore of a single framework. Owing to its water stability and anionic skeleton, the removal ability of four dyes with different charges and sizes by the compound was investigated. The compound, maintaining the negative charge density, effectively adsorbed the cationic methylene blue (MB) dye, while the elimination of anionic methyl orange (MO) and Congo red (CR) dyes was not observed owing to electrostatic repulsion. Additionally, the compound displayed size-dependent adsorption as evidenced by its non-adsorption of the cationic rhodamine B (RhB) dye. The compound exhibited a high MB adsorption capacity with a maximum of 689.93 mg g−1. The experimental data agreed well with the Langmuir isotherm model, and the adsorption process could be marked as a pseudo-second-order kinetic model. The MB adsorption of the compound could be attributed to electrostatic interactions due to its anionic framework and weak interactions. [ABSTRACT FROM AUTHOR]

In advanced oxidation processes (AOPs), the degradation of organic pollutants by the oxidation of reactive oxygen species (ROS) generated from the interaction between H2O2 and active species Fe2+/Fe3+ has gained significant attention. The cycle of Fe2+/Fe3+ in the catalytic oxidation plays a key role. Herein, a kind of N-doped carbon encapsulated FeMoxOy nanocrystalline material (FeMo@NC) was fabricated using a precipitation–calcination approach and applied to degrade organic pollutants in AOPs. The composite catalyst presents efficient catalytic activity for removing rhodamine B (RhB), methylene blue (MB), congo red (CR) and methyl orange (MO). The facilitating effect of Mo on the Fe2+/Fe3+ cycle and the phase structure and composition of the catalyst on the degradation was explored. Meanwhile, the recovery and reusability of the catalyst were assessed, proving its excellent stability in the degradation process. Quenching experiments demonstrate that the catalyst can activate H2O2 to generate singlet oxygen (1O2) that serves as the main ROS to degrade RhB, and the degradation pathway and mechanism are then proposed. [ABSTRACT FROM AUTHOR]

Photocatalytic and antibacterial properties of PbS:Ag (PA) and rGO-blended PbS:Ag (rPA) nanoparticles (NPs) have been compared and reported in this paper. Chemical precipitation and one-pot synthesis methods were used to synthesize NPs of PA and rPA. X-ray diffraction (XRD) studies reveal a cubic crystal structure for both samples, with preferential growth along the (200) plane. Crystallite sizes were 55 and 41 nm for PA and rPA, respectively. Scanning electron microscopy (SEM) images of rPA revealed clustered grains. Both samples exhibited Pb–S bands in Fourier-transform infrared spectroscopy (FTIR) studies. Near band edge emissions occurred at 504, 520, 539 and 595 nm for both PA and rPA. The inclusion of rGO into PA led to lattice misfit, crystal growth disorders, and increased grain boundary scattering. This series of structural disruptions contributed to a reduction in the photoluminescence (PL) intensity for the rPA composite. A higher degradation efficiency of 95.4% was achieved for the rPA catalyst against Rhodamine B dye under visible light. The antibacterial activity of PA is increased with rGO inclusion due to increased generation of reactive oxygen species (ROS). [ABSTRACT FROM AUTHOR]

This paper investigates the impact of annealing temperature on the photocatalytic degradation efficiency of rhodamine B (rhB) using a montmorillonite/zinc-oxide (MMT/ZnO) nanocomposite. The MMT/ZnO nanocomposites, synthesized through a chemical method, are annealed for one hour at 300°C, 500°C, and 700°C. The study involves a comprehensive analysis of sample composition, surface morphology, and structure using various analytical methods, including Energy Dispersive X-ray Spectroscopy (EDX), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, and Fourier Transform Infrared Spectroscopy (FTIR). RhB degradation efficiency is assessed by monitoring changes in dye concentration in the solution after exposure to UVC radiation, measured with UV-Vis spectroscopy. By-products resulting from the photocatalysis process are identified through LCMS analysis. The results demonstrate that MMT/ZnO annealed at 500°C (referred to as MZ@500) exhibits the highest capability for rhB decomposition, achieving a remarkable 95.5% degradation efficiency with 10 ppm of rhB and 0.1 g/L of MZ@500. Furthermore, this composite effectively fragments the dye's chromophore structure into smaller, ring-broken compounds. [ABSTRACT FROM AUTHOR]

Photo-Fenton catalysis plays an important role in the degradation of organic pollutants in environmental sewage. In this paper, magnetic 0D/1D ZnFe2O4/ZnCO3 rod-like nanocomposites were fabricated by a simple one-pot solvothermal method, and then the produced magnetic 0D/1D ZnFe2O4/ZnO rod-like nanocomposites were formed via calcination at high temperature. The obtained 0D/1D ZnFe2O4/ZnCO3 has been fully investigated by x-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, x-ray photoelectron spectroscopy, and vibrating sample magnetometry. Furthermore, the photocatalytic Fenton reaction of these two catalysts has been preliminarily evaluated for the degradation performance of organic dyes and antibiotics in wastewater. The results showed that, under visible-light irradiation, the ZnFe2O4/ZnCO3 composite material and its product, ZnFe2O4/ZnO, after high-temperature firing can achieve more than 90% photo-Fenton catalytic degradation of Rhodamine B (RhB) and tetracycline (TC) within 30 min, superior to that of ZnFe2O4, ZnCO3 , and ZnO monomers due to their larger specific surface area and more active sites. The magnetization saturation values of ZnFe2O4/ZnCO3-2 and ZnFe2O4/ZnO-2 were, respectively, around 34.20 emu/g and 15.00 emu/g, indicating that both have good magnetic recovery properties. After five cycles of experiments, the photo-Fenton catalytic properties of ZnFe2O4/ZnCO3-2 and ZnFe2O4/ZnO-2 on TC decreased slightly within 30 min, but the Fenton catalytic properties of RhB still maintained more than 98%, indicating that both have good magnetic recovery properties and strong structural stability. A possible photo-Fenton catalytic mechanism has been proposed based on free radical identification, electrochemical impedance spectra, photocurrent curves, and a Mott–Schottky diagram. This study provided two catalysts with excellent performance for the photo-Fenton catalytic degradation of pollutants in water. [ABSTRACT FROM AUTHOR]

Decatungstate (W10O324−, DT) is a metastable polyoxometalate anion which presents excellent photocatalytic ability. In order to stabilize the DT species, four decatungstate-based coordination polymer compounds with different DT coordination modes, namely [Cu2(3-bpo)2(H2O)2(DMSO)2][W10O32]·14H2O (1), [Cu2(3-bpo)2(DMSO)4][W10O32] (2), [Cu2(4,4′-bipy)4][H2W10O32] (3) and [Cu(4,4′-bipy)3(DMSO)(H2O)][TBA][HW10O32]·H2O (4) (DMSO = dimethyl sulfoxide, 3-bpo = 2,5-bis(3-pyridyl)-1,3,4-oxadiazole, 4,4′-bipy = 4,4′-bipyridine, TBA = tetrabutylammonium) were synthesized under controlled solvothermal conditions in the mixed solvent of DMSO and H2O. The heterogeneous photocatalytic activity of these four compounds in the degradation of rhodamine B was tested and the results show that they possess fairly high photocatalytic activity without leaching of DT during the reaction. The effect of the coordination modes of terminal oxygen (Ot) atoms in DT anions on the activity was investigated. [ABSTRACT FROM AUTHOR]

One of the important research components of photocatalytic research is the development of new photocatalysts, and recent studies have shown the rise of borate‐type photocatalysts. This paper focuses on the photoreduction of potassium dichromate and the photodegradation of rhodamine B by two borate composites under simulated sunlight. A coral‐like borate was obtained by sol‐gel preparation and then assembled by photodeposition with Pt nanoparticles dots or CuO particles to obtain the new composites with excellent performance. The kinetic constants of photocatalytic properties of 2 %Pt/Gd0.85Ce0.15B5O9 and 2.5 %CuO/Gd0.90Ce0.10B5O9 samples in the reduction and degradation reactions are 0.0050 min−1 and 0.0150 min−1, which are 25 and 4.2 times of the intrinsic GdB5O9 sample respectively. The results of the study indicate the research promise of developing new visible photocatalysts based on borates, especially for photocatalytic applications for pollutant removal. [ABSTRACT FROM AUTHOR]

One of the important research components of photocatalytic research is the development of new photocatalysts, and recent studies have shown the rise of borate‐type photocatalysts. This paper focuses on the photoreduction of potassium dichromate and the photodegradation of rhodamine B by two borate composites under simulated sunlight. A coral‐like borate was obtained by sol‐gel preparation and then assembled by photodeposition with Pt nanoparticles dots or CuO particles to obtain the new composites with excellent performance. The kinetic constants of photocatalytic properties of 2 %Pt/Gd0.85Ce0.15B5O9 and 2.5 %CuO/Gd0.90Ce0.10B5O9 samples in the reduction and degradation reactions are 0.0050 min−1 and 0.0150 min−1, which are 25 and 4.2 times of the intrinsic GdB5O9 sample respectively. The results of the study indicate the research promise of developing new visible photocatalysts based on borates, especially for photocatalytic applications for pollutant removal. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C3N4) faces limitations in its photocatalytic applications due to its inherently wide bandgap (2.7 eV), low utilization of visible light, and a high rate of recombination of photogenerated electron–hole pairs. Defect engineering can effectively enhance the ability of g-C3N4 photocatalysts to address environmental pollution. In this paper, g-C3N4 materials with N defects (AA-CN15) were successfully prepared by using urea as a hydrogen bond donor and ammonium acetate as a hydrogen bond acceptor. The catalyst exhibits a broader range of visible light absorption, a lower rate of photogenerated electron–hole recombination, and a larger specific surface area, thanks to the formation of N defects in the N1 (C=N–C) vacancy. The formation of N defects reduces the band gap width of AA-CN15 from 2.85 eV to 1.90 eV compared to U-CN. The degradation rate of AA-CN15 in a 30 mg/L MB solution under visible light irradiation can reach 91.4% within 100 min, which is 7.2 times higher than that of U-CN. This study addresses the limitations and drawbacks of traditional defect introduction methods, offering a novel approach for the synthesis of N defect g-C3N4 materials. [ABSTRACT FROM AUTHOR]

Water pollutants of non-biodegradable toxic aromatic dye including Methylene blue (MB) and Rhodamine (RhB) are extremely carcinogenic thiazines used in various industries such as leather industry, paper industry, and the dyeing industry. The presence of dyes in wastewater causes severe threats to human health that are responsible for various harmful chronic or acute diseases and also shows an adverse impact on the environment as it reduces transparency and is harmful to water microorganisms. To overcome severe issues, many traditional techniques have been used to remove toxic pollutants, but these methods are insufficient to remove chemically stable dyes that remain in the treated wastewater. However, the photocatalytic degradation process is an efficient approach to degrade the dye up to the maximum extent with improved efficiency. Therefore, in this work, a new class of two-dimensional (2D) transition metal carbide of Titanium Carbide (Ti3C2Tx) MXene material was used for the organic dyes degradation such as MB and RhB using a photocatalytic process. A layered structure of hexagonal lattice symmetry of Ti3C2Tx MXene was successfully synthesized from the Titanium Aluminum Carbide of Ti3AlC2 bulk phase using an exfoliation process. Further, the XRD spectrum confirms the transformation of bulk MAX phase having (002) plane at 9.2° to Ti3C2Tx MXene of (002) plane at 8.88° confirms the successful removal of Al layer from MAX phase. A smooth, transparent, thin sheet-like morphology of Ti3C2Tx nanosheet size were found to be in the range of 70 to 150 nm evaluated from TEM images. Also, no holes or damages in the thin sheets were found after the treatment with strong hydrofluoric acid confirms the formation Ti3C2Tx layered sheets. The synthesized Ti3C2Tx MXene possesses excellent photocatalytic activity for the degradation of dyes MB, RhB, and mixtures of MB and RhB dyes. MB dye degraded with a degradation percentage efficiency of 99.32% in 30 min, while RhB dye was degraded upto 98.9% in 30 min. Also, experiments were conducted for degradation of mixture of MB and RhB dyes by UV light, and the degradation percentage efficiency were found to be 98.9% and 99.75% for mixture of MB and RhB dye in 45 min, respectively. Moreover, reaction rate constant (k) was determined for each dye of MB, RhB, and mixtures of MB and RhB and was found to be 0.0215 min−1 and 0.0058 min−1, and for mixtures, it was 0.0020 min−1 and 0.009 min−1, respectively. [ABSTRACT FROM AUTHOR]