Rhodamine B Dye Research Articles

Photocatalytic degradation of Rhodamine B dye using low‐cost pyrofabricated titanium dioxide quantum dots‐kaolinite nanocomposite

In this study, we report a simple technique for the pyrofabrication of a novel photocatalyst of titanium dioxide quantum dots‐kaolinite nanocomposite (TiO2‐QDs‐Kao) used for rhodamine B (RhB) dye degradation. The photocatalyst was characterized by using different analytical techniques, including XRD, XRF, XPS, FTIR, DTA/TGA, SEM–EDX, TEM, BET, BJH, ZP and UV–Vis DRS. The photocatalytic degradation of RhB was performed in aqueous solutions using the sustainable sunlight energy under atmospheric conditions and fixed neutral medium (pH = 7). The produced photocatalyst exhibited optical band gap energy of 2.85 eV, an improved large specific surface area of 107.724 m2/g with pore radius of 1.45 nm and total pore volume of 0.123 cm3/g. The study indicated a maximum 91% degradation efficiency of RhB after 120 min using the optimum dose 1,400 mg/l of the TiO2‐QDs‐Kao photocatalyst. The degradation of RhB dye fitted the Langmuir first‐order kinetics with rate constant 0.0151 min−1. The radical trapping experiments based on scavengers confirmed that the mechanism of photocatalytic degradation activity was potentially based on electron (e−) and hole (h+) conduction band. The potential energy of the valence and conduction bands EVB and ECB were calculated 2.73 and −0.12 eV, respectively. A triple reusability study confirmed a high stability of TiO2‐QDs‐Kao photocatalyst with detected degradation efficiencies of 91.0, 89.9, 88.8 and 87.5%, respectively.

CuO decorated graphene TiO2 derived MIL-125 nanocomposite with enhanced photo-response as a highly efficient indirect sunlight driven photocatalyst

Advanced Oxidation Processes (AOPs) are utilized to remove a large range of pollution in water by heterogeneous photocatalysis with production of electron-hole pairs by light. Herein, we showed the preparation of GO/MIL-125 by a simple solvothermal method and then the addition CuO by a simple wet impregnation method. MIL-125 and their derived have attracted considerable attraction due to high earth’s crust abundance, low toxicity, unique photo redox property and photocatalytic application. The photocatalyst, 5CuO/10GO/MIl-125 which was calcined at 600 ◦C (CuTG-600), with a bandgap of 2.82 eV, was utilized to degrade Rhodamine B (RhB) dye which is oxidized to CO2 and H2O. The characterization of different samples was investigated using FT-IR, XRD, XPS, SEM, EDX mapping, UV–vis spectroscopy, Linear sweep voltammetry, photocurrent response, electrochemical impedance spectroscopy (EIS) and Mott-Schottky plots. The combination of GO and CuO increases the degradation activity of RhB dye under irradiation of visible light (λ = 380–780), (blue LED lamp (λ = 450 nm) and red LED lamp (λ = 610 nm)) and the higher results were showed by 5CuTG-600. Photodegradation kinetics were explained by various parameters such as calcination, catalyst type, pH, dye concentration, catalyst dose, different lamps with different wavelengths, different scavengers and reusability. Furthermore, The Photoelectrochemical test results were noticed that the activity of 5CuTG-600 is higher than that of TG-600 and T-600 due to higher donor concentration (ND), and lower recombination process of the charge carrier. Finally, we obtain 5CuTG-600 which acts as an important photocatalyst and is used in environmental and electrochemical applications.

Characterization of self-dyed silk yarn with Rhodamine B dye for fashion applications

PurposeThe textile industry has consumed large quantities of water and discharged large volumes of wastewater in the dyeing process. The study aims to characterize self-dyed silk with Rhodamine B (RhB) for fashion applications to reduce textile hazards to the environment and increase the added value of silk.Design/methodology/approachBombyx mori was fed with RhB-colored mulberry leaves (1500 ppm). The effects of self-dyeing were investigated via color strength K/S, Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscope, X-ray diffraction, tensile strength, color fastness to washing, rubbing, perspiration and light.FindingsSelf-dyed silk possesses effective coloration and impressive color fastness (4–5/5), higher crystalline index (CrI) (73.26 ± 2.28%), less thermal stability and tenacity, slight change in amino acid composition compared with the pristine and no existence of harmful aromatic azo amines and arylamine salts.Practical implicationsThe application of self-dyed silk with RhB dye has expanded new technology into fashion industry, contributing partly to economic growth and adding value to silk in the global supply chain. Besides, the self-dyeing will yield practical values in the reduction of dyeing discharge in textile industry.Originality/valueSelf-dyed silk was characterized for textile applications in comparison with pristine silk in terms of color strength and fastness as well as determined its polymeric properties relating to crystallinity, morphology, chemical composition, tensile properties and thermal stability which have not been investigated before.

Photocatalytic activity of the novel triazine-based magnetic core–shell Cu nanocomposite for degradation of RhB and MB via air oxidation and Cr(VI) reduction

This study examines the degradation of methylene blue (MB) and Rhodamine B (RhB) and also reduction of Cr(VI) from water via novel thiol-functionalized magnetic core–shell Fe3O4/MPTMS/Ligand and Fe3O4/MPTM/Ligand-Cu nanoparticles as recyclable photocatalysts. The structure and morphology of the synthesized compounds were confirmed by different techniques. Nanospherical particles were identified through FE-SEM, TEM and HR-TEM analysis. The oxidation states and also bonding type of different elements of nano compounds were recognized by XPS spectra. According to the PL spectra, the electron/hole recombination of Fe3O4/MPTMS/Ligand-Cu decreased in comparison with Fe3O4/MPTMS/Ligand. The investigation of the optical properties of the synthesized samples showed that optical band gap value decreased at each stage and was about 2.09 eV for Fe3O4/MPTMS/Ligand-Cu nanoparticles, which sufficiently absorbed visible light. The Fe3O4/MPTMS/Ligand and Fe3O4/MPTMS/Ligand-Cu nanoparticles were used to degrade MB and RhB dyes under sun and visible light irradiation without using external oxidation agent. According to the TOC results, more than 80 percent of dyes were decomposed to CO2. Based on the results of the scavenger tests, the hydroxyl radical could play a significant part in MB and RhB photocatalytic degradation and also reduction of Cr(VI) by Fe3O4/MPTMS/Ligand-Cu and Fe3O4/MPTMS/Ligand nanoparticles under visible and sun light irradiation. The excellent photoelectrochemical properties of Fe3O4/MPTMS/Ligand-Cu compared with Fe3O4/MPTMS/Ligand are in agreement with its higher photocatalytic activity for RhB and MB degradation and Cr(VI) reduction. Generally, the advantage of Fe3O4/MPTMS/Ligand-Cu and Fe3O4/MPTMS/Ligand nanoparticles is that they can be separated using an external magnet and used for subsequent reactions.

Lignocellulose biomatrix zero-valent cobalt nanoparticles: a dip-catalyst for organic pollutants degradation

Pollutant removal based on natural materials got comprehensive spread utilization because of their high efficiency in degrading toxic organic pollutants in an aqueous medium. In this work, a redox dip-nanocatalyst based on cobalt nanoparticles (Co NPs) at a size of approximately 100 nm anchored on lignocellulose biomatrix via wet impregnation was used for the degradation of model pollutants. The cobalt ions immobilized on rice husk (RH) biomass fibers were reduced to their respective zero-valent state by treatment with sodium borohydride (NaBH4). The as prepared catalyst was named as RH@Co NPs. Various analytical characterization techniques viz. Fourier transforms infrared (FTIR) spectroscopy, Field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), X-Ray photoemission spectroscopy (XPS), and X-ray diffraction analysis (XRD) were used to examine functional group analysis, morphological characteristics, stability, elemental composition, and crystalline nature of the as-prepared RH@Co nanocatalyst respectively. The catalytic properties of the RH@Co NPs were tested using different nitrophenols viz. 2-nitrophenol (2-NP), 3-nitrophenol (3-NP), 4-nitrophenol (4-NP), and dyes viz. congo red (CR), methyl orange (MO), methylene blue (MB), and rhodamine B (RB). It was found that kinetic data followed zeroth order kinetics for the degradation of model pollutants. The RH@Co showed good catalytic activity for 2-NP, 3-NP, and 4-NP with apparent rate constants (kapp) of 0.019 min−1, 0.029 min−1, and 0.0416 min−1, respectively. Similarly, in the case of CR, MO, RB, and MB dyes, the kapp was 0.067 min−1, 0.12 min−1, 0.16 min−1, and 0.085 min−1, respectively. These results present the potential application of RH@Co as a sustainable and retrievable nanocatalyst for the remediation of pollutants. Furthermore, the results are general and can be used for the reduction of other organic pollutants.

Characterization, catalytic, and recyclability studies of nano-sized spherical palladium particles synthesized using aqueous poly-extract (turmeric, neem, and tulasi)

Green synthesis of noble metal nanoparticles (NPs) has gained immense significance compared to other metal ions owing to their unique properties. Among them, palladium ‘Pd’ has been in the spotlight for its stable and superior catalytic activity. This work focuses on the synthesis of Pd NPs using the combined aqueous extract (poly-extract) of turmeric (rhizome), neem (leaves), and tulasi (leaves). The bio-synthesized Pd NPs were characterized to study its physicochemical and morphological features using several analytical techniques. Role of Pd NPs as nano-catalysts in the degradation of dyes (1 mg/2 mL stock solution) was evaluated in the presence of a strong reducing agent (sodium borohydride; SBH). In the presence of Pd NPs and SBH, maximum reduction of methylene blue (MB), methyl orange (MO), and rhodamine-B (Rh–B) dyes was observed under 20nullmin (96.55 ± 2.11%), 36nullmin (96.96 ± 2.24%), and 27nullmin (98.12 ± 1.33%), with degradation rate of 0.1789 ± 0.0273 min−1, 0.0926 ± 0.0102 min−1, and 0.1557 ± 0.0200 min−1, respectively. In combination of dyes (MB + MO + Rh–B), maximum degradation was observed under 50nullmin (95.49 ± 2.56%) with degradation rate of 0.0694 ± 0.0087 min−1. It was observed that degradation was following pseudo-first order reaction kinetics. Furthermore, Pd NPs showed good recyclability up to cycle 5 (72.88 ± 2.32%), cycle 9 (69.11 ± 2.19%) and cycle 6 (66.21 ± 2.72%) for MB, MO and Rh–B dyes, respectively. Whereas, up to cycle 4 (74.67 ± 0.66%) during combination of dyes. As Pd NPs showed good recyclability, they can be used for several cycles thus influencing the overall economics of the process.

Green synthesis of Zinc oxide nanoparticles using lemon extract for waste water treatment

The present work represents the study of effects on the photocatalytic activity of green synthesized Zinc oxide nanoparticles by using Zinc nitrate as a precursor with lemon juice extract for various temperatures (50˚C, 60˚C, 70˚C, 80˚C). XRD studies confirms the crystalline structure of green synthesized nanoparticles. The characteristic absorption peak of zinc oxide nanoparticles had been verified using UV–Visible and FTIR spectrum. The morphological study of the nanoparticles had been investigated by Scanning electron microscope (SEM). The Photodegradation of ZnO nanoparticles on Rhodamine-B(RhB) dye had been studied.

Comparative Evaluation of Flexural Strength, Modulus of Elasticity, and Microleakage of Three Different Glass Ionomer Restorative Materials in Class V Preparations – An In vitro Study

Aims: Flexural strength, modulus of elasticity, and microleakage evaluation of three glass ionomer restorative materials in class V preparations. Materials and Methods: Twenty bar-shaped specimens each of Type-II glass-ionomer cement (GIC), Zirconomer and Type-IX GIC were prepared by inserting freshly mixed cements into 25 mm × 2 mm × 2 mm polyvinylacetate moulds followed by storage in artificial saliva for 24 h at 37°C. Samples were then rinsed, polished, and tested in autograph universal testing machine for flexural strength and modulus of elasticity using three-point bending test. Standardized Class V cavities in 60 extracted human premolars of dimensions 3 mm × 2 mm × 1.5 mm were prepared, divided at random into three groups of twenty each and restorations were done using Type-IX GIC, Type-II GIC, and Zirconomer. Teeth were immersed in 1%wt Rhodamine-B dye after thermocycling for 24 h, split bucco-lingually in longitudinal section and evaluated for microleakage under a stereomicroscope. Results: Flexural strength evaluation showed that Zirconomer had the highest and Type-II GIC had the lowest flexural strengths that was statistically significant (P < 0.05; analysis of variance [ANOVA]-Tukey Honestly Significant Difference [HSD]). Analysis of modulus of elasticity revealed that Type-IX GIC had the highest and Type-II GIC had the lowest modulus and the difference was significant statistically (P < 0.05; ANOVA-Tukey HSD). Occlusal microleakage was the highest in samples restored with Zirconomer (50% of the teeth), whereas samples restored with Type IX GIC showed no microleakage. At the gingival margins, 60% of both Type-IX GIC and Zirconomer restored samples exhibited no microleakage and 55% of Type-II GIC restored samples showed no microleakage. Conclusion: Within the limitations of this study, Type IX GIC exhibited good flexural strength, low modulus of elasticity, and least microleakage followed by Type II GIC and Zirconomer.

Exploring ZnO/Montmorillonite photocatalysts for the removal of hazardous RhB Dye: A combined study using molecular dynamics simulations and experiments

Photocatalytic degradation of pollutants by nanocomposites is one of the most interesting methods used around the world. However, it is difficult for photocatalysts to provide excellent absorption of the photons of light, and at the same time recombination of the photogenerated electron-hole and agglomeration of the nanoparticles is applicable. Therefore, a catalyst is fulfilling these criteria by supporting on clay particles, such as ZnO/Montmorillonite (ZnO/Mt) nanocomposite which is synthesized in the present work by simple co-precipitation approach. Assessing the efficiency of the Rhodamine B (RhB) photocatalytic breakdown process is showed that the ZnO/Mt photocatalyst exhibited better photocatalytic performance in comparison to pure ZnO. The enhanced photocatalytic performance of the ZnO/Mt photocatalyst is attributed to the beneficial interaction between montmorillonite and ZnO nanoparticles. Further, theoretical analysis is conducted to examine the RhB dye adsorption on the ZnO/Mt photocatalyst. At the first, all used compounds are optimized by DFT-D calculations; the HOMO/LUMO and the total energy are also obtained. Then, the molecular dynamic (MD) simulation is used for ZnO adsorption on Montmorillonite (Mt) by using Monte Carlo adsorption locator module. After forming nanocomposite, the adsorption energy of RhB (Ead) on ZnO/Mt is applied, indicating that the adsorption process is a result of negative interaction energy. Additionally, the energy required for RhB to adsorb on ZnO/Mt is found to be greater than the energy required for RhB to adsorb on Mt alone.

Synthesis of bagasse nanocellulose-filled composite polyurethane xerogel for the efficient adsorption of Rhodamine-B dye from aqueous solution: investigation of adsorption parameters.

In this study, polyurethane (PU)-based xerogels were synthesized by using the biobased polyol derived from chaulmoogra seed oil. These polyol was used for the preparation of PU xerogels using methylene diphenyl diisocyanate hard segment and polyethylene glycol (PEG6000) as soft segment with 1,4-diazabicyclo[2, 2, 2]octane as catalyst. Tetrahydrofuran, acetonitrile and dimethyl sulfoxide were used as the solvents. Nanocellulose (5wt %) prepared from bagasse were added as filler, and the obtained composite xerogels were evaluated for chemical stability. The prepared samples were also characterized by using SEM and FTIR. Waste sugarcane bagasse nanocellulose proved as a cheap reinforcer in the xerogel synthesis and for the adsorption of Rhodamine-B dye from the aqueous solution. The factors that affect the adsorption process have been studied including the quantity of the adsorbent (0.02-0.06g), pH (6-12), temperature (30-50) and time (30-90). Central composite design for four variables and three levels with response surface methodology has been used to get second-order polynomial equation for the percentage dye removal. RSM was confirmed by the measurement of analysis of variance. Increase in the pH and quantity of the adsorbent was found to increase the sorption capacities of the xerogel (NC-PUXe) towards rhodamine B, maximum adsorption.

First Experimental Evidence of Anti-Stokes Laser-Induced Fluorescence Emission in Microdroplets and Microfluidic Systems Driven by Low Thermal Conductivity of Fluorocarbon Carrier Oil

With the advent of many optofluidic and droplet microfluidic applications using laser-induced fluorescence (LIF), the need for a better understanding of the heating effect induced by pump laser excitation sources and good monitoring of temperature inside such confined microsystems started to emerge. We developed a broadband highly sensitive optofluidic detection system, which enabled us to show for the first time that Rhodamine-B dye molecules can exhibit standard photoluminescence as well as blue-shifted photoluminescence. We demonstrate that this phenomenon originates from the interaction between the pump laser beam and dye molecules when surrounded by the low thermal conductive fluorocarbon oil, generally used as a carrier medium in droplet microfluidics. We also show that when the temperature is increased, both Stokes and anti-Stokes fluorescence intensities remain practically constant until a temperature transition is reached, above which the fluorescence intensity starts to decrease linearly with a thermal sensitivity of about −0.4%/°C for Stokes emission or −0.2%/°C for anti-Stokes emission. For an excitation power of 3.5 mW, the temperature transition was found to be about 25 °C, whereas for a smaller excitation power (0.5 mW), the transition temperature was found to be about 36 °C.

Construction of heterogeneous structures of MIL-101(Fe)/Ce/g-C3N4 nanocomposites for enhanced photocatalytic activity under visible light

A heterostructured MIL-101(Fe)/Ce/g-C3N4 (MCCN) composite was designed and synthesized by solvothermal method. The composite was characterized by XRD, SEM, EDS, FT-IR, BET, XPS, UV–Vis DRS, PL and EIS. The MCCN photocatalyst exhibits superior photocatalytic performance for the degradation of rhodamine B (RhB) and methylene blue (MB), and the efficiencies are found to be 90.36% and 88.17%, respectively. The kinetic constants k of MCCN-3 against RhB and MB dyes are 0.04094 min−1 and 0.03319 min−1, respectively, under visible light for 75 ​min irradiation. The improved degradation efficiency of MCCN attributed to the enhanced light absorption and the transport channels of electron-hole pairs by forming a heterojunction between MIL-101(Fe) and Ce/g-C3N4 with a favourable band position. Moreover, the possible mechanism of photocatalytic degradation of dyes was proposed though free radical trapping experiments. This work provides an effective way for constructing novel visible-light-driven photocatalyst in the removal of organic molecules from waste water.

π-Electron-Extended Triazine-Based Covalent Organic Framework as Photocatalyst for Organic Pollution Degradation and H2 Production from Water.

Herein, we report the efficient preparation of π-electron-extended triazine-based covalent organic framework (TFP-TPTPh COF) for photocatalysis and adsorption of the rhodamine B (RhB) dye molecule, as well as for photocatalytic hydrogen generation from water. The resultant TFP-TPTPh COF exhibited remarkable porosity, excellent crystallinity, high surface area of 724 m2 g-1, and massive thermal stability with a char yield of 63.41%. The TFP-TPTPh COF demonstrated an excellent removal efficiency of RhB from water in 60 min when used as an adsorbent, and its maximum adsorption capacity (Qm) of 480 mg g-1 is among the highest Qm values for porous polymers ever to be recorded. In addition, the TFP-TPTPh COF showed a remarkable photocatalytic degradation of RhB dye molecules with a reaction rate constant of 4.1 × 10-2 min-1 and an efficiency of 97.02% under ultraviolet-visible light irradiation. Furthermore, without additional co-catalysts, the TFP-TPTPh COF displayed an excellent photocatalytic capacity for reducing water to generate H2 with a hydrogen evolution rate (HER) of 2712 μmol g-1 h-1. This highly active COF-based photocatalyst appears to be a useful material for dye removal from water, as well as solar energy processing and conversion.

Effect of size on physicochemical, antibacterial, and catalytic properties of Neolamarckia cadamba (burflower-tree) synthesized silver/silver chloride nanoparticles.

Aqueous extract of Neolamarchia cadamba leaves were used in the synthesis of silver/silver chloride nanoparticles (Ag/AgCl NPs). Further they were separated based on their using step-wise centrifugation approach at 09,000, 12,000, and 15,000rpm. Thus obtained NPs were characterized for their physicochemical features. NPs showed maximum absorbance at 455nm, 415nm, and 402nm. All the NPs were found to be crystalline in nature with average crystallite size (nm) of 58.31, 23.43, and 09.56. Particle size distribution (nm) of NPs was observed to 435.43, 276.75, and 105.49, Surface charge (-mV) of NPs was observed to be 14.59, 23.90, and 32.17. Ag/AgCl NPs-rpm@15,000 showed antibacterial activity against Escherichia coli, coagulase-negative Staphylococci, and Staphylococcus aureus with zone of inhibition (mm) of 16.65, 13.69, and 14.02 at 50µg per well, respectively. Ag/AgCl NPs-rpm@15,000 showed excellent catalytic activity in degradation of methyl red, methylene blue, rhodamine-B, and methyl orange dyes in the presence of sodium borohydride under 4, 6, 5, and 4min with pseudo-first order rate constant (min-1) of 0.981 (96.4%), 0.666 (97.1%), 0.905 (98.1%), and 1.032 (96.6%), respectively. Furthermore, Ag/AgCl NPs-rpm@15,000 showed good catalytic efficiency even under different dye combinations. Total combination was degraded under 18min.

Adsorption of RhB dye on soy protein isolate-based double network spheres: Compromise between the removal efficiency and the mechanical strength

Soy protein isolate-based double network spheres (SPIDNS) were designed and adopted for the first time for Rhodamine B (RhB) dye removal from wastewater. The SPIDNS were prepared through the aziridine crosslinker and the Ca2+ ionic double crosslinking method with major crosslinking agents of soy protein isolate and sodium alginate, in which aziridine crosslinker was also employed as a modifier to regulate the mechanical strength. The physicochemical properties of the materials were explored by numerous technologies, including SEM NMR, FT-IR, and XPS, which confirmed the chemical and physical crosslinked networks of SPIDNS being established after aziridine crosslinker and Ca2+ ionic crosslinking process. Adsorption performances for RhB removal were investigated under various conditions by using SPIDNS with different dosages of aziridine crosslinker for 0%, 1.8%, 3.6%, 5.3%, 6.9%, and 8.5%. Experimental results demonstrated that the mechanical stability of the adsorbent was enhanced with increasing the amount of aziridine crosslinker from 0% to 8.5%; whereas, the adsorption capacity decreased from 190 to 120 mg/g. Therefore, a compromise between the removal efficiency and the mechanical strength should be taken into account. Studies of adsorption kinetics, isotherms, and thermodynamics displayed that the spontaneous RhB adsorption on SPIDNS was well described by a pseudo-second-order kinetic model and Langmuir isotherm model with monolayer adsorption behavior, for which both the correlation coefficients R2 were higher than 0.99. Moreover, electrostatic interactions between the positively charged RhB molecules and the negatively charged SPIDNS were proposed as the principal adsorption mechanism, which was confirmed by Zeta potential analysis. The good mechanical stability and spherical porous structure make the SPIDNS with reliability and potential for practical application.

Construction of alkalized MXene-supported CoFe2O4/CS composites with super-strong adsorption capacity to remove toxic dyes from aqueous solution

Owing to the unique surface microstructure, plentiful active sites and rich functional groups, two-dimensional transition metal carbide/nitride (MXene) is getting more and more attention in the field of pollutant removal. Now, we design a new magnetic adsorbent with CoFe2O4/chitosan (CS) composite supported onto alkalized MXene (alk-MXene) sheet using a facile hydrothermal and self-assembly technique. The structure and surface properties of the as-synthesized alk-MXene/CoFe2O4/CS composites are characterized by XRD, SEM, FTIR, TGA, BET and XPS. Batch experiments on adsorbing Congo Red (CR), Rhodamine B (RhB) and Malachite Green (MG) dyes are carried out, where the introduction of CoFe2O4/CS into alk-MXene can greatly enhance the adsorption capacity for cationic and anionic dyes. Notably, it is concluded that 24 h is a more suitable etching time to improve the adsorption performance of the composite during the synthesis process. An ultra-high adsorption capacity of S1 achieves up to 2095.9, 1333.9 and 537.6 mg g−1 for CR, RhB and MG dyes, respectively. The influence factors (etching time, pH values, contact time, initiate concentration and temperature) on the adsorption behaviors are discussed, where spontaneous and endothermic adsorption nature is confirmed. Analyses of the adsorption mechanism indicate that the synergistic effects of electrostatic interaction, π-π interaction and hydrogen bonding lead to superior adsorption abilities of the alk-MXene/CoFe2O4/CS composites. In a word, with the specific consideration on the advantages of MXene, CoFe2O4 and CS, this study offers a new track to obtain the MXene-based magnetic adsorbents with the simultaneous and high-efficiency removal of cationic and anionic dyes from the aqueous solutions.

Synthesis of hematite (α-Fe2O3) nanoparticles by a liquid-phase microplasma-assisted electrochemical process for photocatalytic activity

Dye contamination is becoming a more significant environmental challenge with the development of the textile industry. Scientists from all over the world are working hard to create new, more efficient ways to reduce environmental pollution through environmentally friendly synthesis techniques. In this regard, hematite (α-Fe2O3) nanoparticles have been synthesized by the novel, quick, cheap, and environmentally safe microplasma technique for the photodegradation of rhodamine-B under direct Sunlight. Thus, the synthesized α-Fe2O3 nanoparticles were characterized by various characterization techniques such as x-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), and ultraviolet-visible spectroscopy (UV–vis spectroscopy). The structural and optical properties were found to vary with changing precursor concentrations. We measured the photocatalytic decolorization efficiency of synthesized hematite (α-Fe2O3) nanoparticles for rhodamine-B dye under direct Sunlight. It was found that α-Fe2O3 nanoparticles exhibited a decolorization capability with 73.75% decolorization of the dye at the rate of 0.04305 g.mg−1.min−1 after 100 min of irradiation, exhibiting excellent performance to remove organic contaminants from wastewater.

Hierarchically porous MIL-100(Fe) with large mesopores for cationic dye adsorption

Iron-based metal organic framework (MIL-100(Fe) (MIL: Materials of the Institut Lavoisier)) is attractive candidate for adsorption, separation, and catalysis owing to their high surface area and permanent porosity. However, most of MIL-100(Fe)s only possess micropores and small mesopores, which prevent the transportation of large guest molecules and hinder their applications in macromolecules. In addition, corrosive hydrofluoric acid (HF)-free synthesis of MIL-100(Fe) can contribute to large scale production. Thus, constructing hierarchically porous HF-free MIL-100(Fe)s with large mesopores is highly desirable. In this study, six HF-free MIL-100(Fe)s were prepared in pure H2O and DMF using FeCl3, Fe(NO3)3 and Fe2(SO4)3 under hydrothermal/solvothermal conditions. The results indicated that applying FeCl3 as iron source and DMF as solvent can form pure MIL-100(Fe) (i.e., Cl-DMF) with abundant (79 ​vol%) mesopores (22 ​nm) and some macropores. The obtained samples were employed in removal of methylene blue (MB), rhodamine B (RhB) and methyl orange (MO) as dyes and chromium(VI) as metal ion. The Cl-DMF exhibited more excellent adsorption performance toward the macromolecular dye RhB compared to other five products. Adsorption of RhB onto Cl-DMF was obeyed the pseudo-second order and Freundlich isothermal models. Maximum adsorption capacity of RhB was 207 ​mg/g for Cl-DMF, which is considerably higher than other MIL-100(Fe)s reported. The adsorption mechanism investigation indicated that it can be related to a combination of physical adsorption and electrostatic reaction.

Eco-friendly approach for ZnO nanoparticles synthesis and evaluation of its possible antimicrobial, larvicidal and photocatalytic applications

The synthesis of nanoparticles (NPs) from plants is a viable eco-friendly approach with applications in different sectors. Thus, we aim to synthesize and characterize zinc oxide NPs (ZnO NPs) from Ficus racemosa L. leaf extract and to evaluate their larvicidal potential against Aedes albopictus larvae, their efficacy against human clinical pathogenic bacteria (Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, and Escherichia coli). Furthermore, we evaluated its use in photocatalytic rhodamine B (RhB) dye degradation and its possible acute toxicity to a non-target organism (Artemia salina). The biosynthesized ZnO NPs were characterized using UV–Vis, XRD, SEM-EDX, TEM, and FT-IR. UV–vis absorption spectrum indicates that the green synthesized ZnO NPs absorb at the wavelength centered at 365 nm, corresponding to the band gap of 3.2 eV. We reported that A. albopictus mosquito larvae were highly susceptible to ZnO NPs, especially when exposed to 250 μg ZnO NPs/mL. The reduction of acetylcholinesterase (AChE) activity and the carboxylesterases phosphatases evaluated was concentration-dependent, constituting a possible mechanism of larvicidal action of NPs. Biosynthesized ZnO NPs also significantly inhibited the growth of the bacterial species evaluated, suggesting good bactericidal activity. Furthermore, the ZnO NPs efficiently degraded RhB dye in an aqueous solution under UV light irradiation, proving promising in dye remediation in wastewater. Finally, ZnO NPs suspension exhibited lower acute toxicity of A. salina after 48 h of exposure. Therefore, our study pioneeringly demonstrates that biosynthesis of ZnO NPs from F. racemosa leaf extract can be a great approach to developing versatile and environmental products.

Single-Step Synthesis of Graphitic Carbon Nitride Nanomaterials by Directly Calcining the Mixture of Urea and Thiourea: Application for Rhodamine B (RhB) Dye Degradation

Recently, polymeric graphitic carbon nitride (g-C3N4) has been explored as a potential catalytic material for the removal of organic pollutants in wastewater. In this work, graphitic carbon nitride (g-C3N4) photocatalysts were synthesized using mixtures of low-cost, environment-friendly urea and thiourea as precursors by varying calcination temperatures ranging from 500 to 650 °C for 3 h in an air medium. Different analytical methods were used to characterize prepared g-C3N4 samples. The effects of different calcination temperatures on the structural, morphological, optical, and physiochemical properties of g-C3N4 photocatalysts were investigated. The results showed that rhodamine B (RhB) dye removal efficiency of g-C3N4 prepared at a calcination temperature of 600 °C exhibited 94.83% within 180 min visible LED light irradiation. Photocatalytic activity of g-C3N4 was enhanced by calcination at higher temperatures, possibly by increasing crystallinity that ameliorated the separation of photoinduced charge carriers. Thus, controlling the type of precursors and calcination temperatures has a great impact on the photocatalytic performance of g-C3N4 towards the photodegradation of RhB dye. This investigation provides useful information about the synthesis of novel polymeric g-C3N4 photocatalysts using a mixture of two different environmentally benign precursors at high calcination temperatures for the photodegradation of organic pollutants.