Cationic Rhodamine Research Articles

Membrane-free Electrolysis Production of Hydrogen Peroxide on Low-cost Metal-free Electrocatalysts for Dye Degradation.

The efficient production of hydrogen peroxide (H2O2) solution was achieved by combining cathodic two-electron oxygen reduction (2e- ORR) and anodic two-electron water oxidation (2e- WOR) in two half-reaction cells. h-BN loaded on carbon fibers (h-BN@C) is prepared and employed as an anode material to catalyze 2e- WOR, while sulfonated commercial BP-2000 carbons (BP-2000-SO3H) were prepared as the cathode materials for 2e- ORR. In a 2 M KHCO3 solution, an overall Faradaic efficiency of 97 % and a total H2O2 production rate of 1872 mmol g-1 h-1 over metal-free electrodes were accomplished in a membrane-free flow cell. The dilute H2O2 solution could be directly used to degrade cationic Rhodamine B or methyl blue and anionic methylene orange dyes in water. This work proved low-cost production of dilute H2O2 solution in simple membrane-free flow cells with single electrolyte and on-site utilization for efficient dye degradation.

Synthesis of zinc oxide semiconductor nanoparticles using natural extract: a systematic evaluation of cationic dye photodegradation influenced by extract concentration, catalyst dose, and pH.

This work obtained zinc oxide nanoparticles (ZnO NPs) using organic components extracted from Waltheria americana at different concentrations. ZnO materials were subsequently applied in the photodegradation of two cationic dyes, Rhodamine B (RB) and methylene blue (MB), at different doses of catalyst and pH. The crystallinity and hexagonal Wurtzite structure of ZnO were established through XRD analysis. The Zn-O bond in the ZnO NPs was confirmed in the FTIR, with the characteristic signals observed in the fingerprint region at ~ 400cm-1. SEM and TEM revealed the formation of quasi-spherical particles with an average size ranging from 2 to 12nm, depending on extract concentrations during synthesis. UV-Vis studies indicated the optical bandgap of ZnO, with values below 3eV, also dependent on extract concentration. PL analysis revealed the recombination of free excitons and defects in ZnO. Photocatalytic studies of ZnO materials demonstrated excellent degradation efficiency of RB and MB dyes, which was influenced by the extract concentration of NPs, while the degradation of MB was enhanced with a 1:1 dye-to-catalyst ratio under acidic conditions. In contrast, due to RB more complex structure, an increased ratio of 1:1 to 1:3 and acidic pH conditions improved its degradation. Green-synthesized ZnO NPs using photocatalysis techniques exhibit significant potential as eco-friendly alternatives for removing contaminants from water.

Ligand modulated charge transfers in Z-scheme configured Ni-MOF/g-C3N4 nanocomposites for photocatalytic remediation of dye-polluted water

The development of photocatalysts must be meticulous, especially when they are designed to degrade hazardous dyes that cause mutagenesis and carcinogenesis. In this meticulous approach, Ni-based metal–organic frameworks with different ligands, including terephthalic acid (NTP), 2-aminoterephthalic acid (NATP), and their composite with g-C3N4 (NTP/GCN, and NATP/GCN) have been synthesized using hydrothermal method. Structural analysis by XRD and ATR-IR revealed synergistic properties due to robust chemical interactions between the NATP-MOFs and GCN systems. A flower-like morphology was observed for both NTP and NATP, while their composites showed mixed-particulate structures mimicking the morphology of GCN. Optical analyses indicated visible-light driven properties with modulated recombination resistance in the system. Among the synthesized bare and composite systems, NATP/GCN exhibited the highest photocatalytic degradation efficiency for the cationic rhodamine B dye (~ 93% in 120 min), while it was relatively less efficient for the anionic Congo red dye, (~ 64% in 120 min). The insights gained from the fundamental characterizations including Mott–Schottky, scavenger, and electrochemical impedance analysis revealed that the amino-groups in NATP/GCN composite offered the band edge potentials suitable for the effective generation of energetic radical species with the improved carrier delocalization, recombination resistance, and charge transfer properties in the composite system through Z-scheme formation. Parametric investigations by varying the concentration of catalyst, dye, and pH along with recycle studies, demonstrated the excellent stability of the developed composites for sustainable photocatalytic applications.

Freezing Conformers for Gas-Phase Förster Resonance Energy Transfer.

Various techniques are available to illuminate geometric structures of molecular ions in gas phase, such as Förster Resonance Energy Transfer (FRET) informing on distances between two dyes covalently attached to a molecule. Typically, cationic rhodamines, which absorb and emit visible light, are used for labeling. Extensive work has revealed that the transition energy of a rhodamine is intricately linked to its nearby microenvironment, with nearby charges causing Stark-shifted emission. This occurs because the inter-dye Coulomb interaction is weaker in the excited state (S1) than in the ground state (S0) due to the increase in polarizability upon excitation. Therefore, absorption and emission spectra, along with FRET efficiencies, provide insights into structural motifs. At room temperature, multiple conformers often co-exist, leading to overlapping absorption bands among different conformers and broad spectra. To study specific conformers, it is necessary to isolate them, for example, using ion-mobility spectrometry. Another approach is to reduce temperature, which results in spectral narrowing and distinct absorption bands, allowing for the selection of specific conformers through selective excitation. Here, we describe the instrumentation used for cryogenically cold FRET experiments and discuss recent results for small model systems, as well as future directions for a technique still in its infancy.

A sustainable strategy to improve photocatalytic degradation properties of CuO and CuO-rGO nanocomposite using Eucalyptus leaf extract

In this study, Copper oxide (CuO) nanoparticles were synthesized using a sustainable approach. The process comprised Eucalyptus leaf extract as both a biological capping agent and a reducing agent. The synthesis process used a one-pot hydrothermal technique to efficiently combine CuO nanoparticles with reduced graphene oxide (rGO). Analytical methods were utilized to investigate the prepared nanocomposite's structural, crystalline, morphological, functional, optical, and thermal characteristics. The prepared sample was analyzed using X-ray diffraction, which revealed that CuO nanoparticles have a monoclinic crystal structure, and no impurity peaks were observed. Field emission scanning microscopes displayed the uniform dispersion of spherical CuO nanoparticles with layered and non-agglomerated, resembling a sponge-like structure of rGO. The microstructural analysis also confirmed the dispersion of copper inside reduced graphene oxide (rGO) sheets. The optical properties, including light absorption and bandgap width, were investigated using UV–visible spectroscopy using bandgap energies of 2.5 and 2.8 eV. In addition, the nanocomposite's ability to degrade cationic Rhodamine 6G and anionic Rose Bengal dyes by photocatalysis was evaluated. The degradation of RB and Rh6G dyes was characterized by nanocatalysis using UV–visible spectroscopy and a pseudo-first-order kinetics model. The pseudo-first-order degradation kinetic rate of Rhodamine 6G was determined to be 2.55 x 10−2 min−1, indicating that the nanocomposite effectively initiates this dye's degradation. The results showed that dye degradation was effective even at reduced catalyst concentrations.

Enhanced photocatalytic degradation of organic dyes by dual heterojunction of ZnO/NiWO4/V2C MXene

Multiphase composite catalysts can be designed for efficient photocatalytic treatment of organic pollutants in wastewater. Herein, the multiphase ZnO/NiWO4/V2C composite catalysts with dual heterojunction and hierarchically assembled nanoflower structures were constructed via a facile two-step hydrothermal and electrostatic self-assembly method. Utilizing NiWO4 and V2C as co-catalysts, these catalysts effectively degraded cationic dyes, methylene blue (MB) and rhodamine B (RhB) under visible light irradiation. The ZnO/NiWO4/V2C catalyst exhibited higher photocatalytic activity than ZnO in the degradation of MB and RhB, with rate constants of 0.0194 min−1 (a 7.43-fold enhancement) and 0.0176 min−1 (a 3.13-fold enhancement). The higher activity can be attributed to the construction of the double heterojunction using NiWO4 and V2C, which can facilitate efficient electron transport, improve charge separation efficiency, and provide more active sites. After four cycles, the ZnO/NiWO4/V2C catalyst still maintained good stability. Consequently, this work can offer a promising approach for environmental pollution treatment.

Ti3C2TX MXene/loofah-derived carbon aerogel for high-efficiency adsorption of organic pollutants in wastewater

The contamination of wastewater by organic pollutants significantly impacts human health and the environment due to their carcinogenic nature and various adverse effects. To address this issue, this study offers a high-efficiency and low-cost biomass-based carbon aerogel adsorbent, which was prepared through the hydrothermal carbonization of loofah, followed by Ti3C2TX MXene impregnation. The aerogel features a porous three-dimensional network structure and a substantial specific surface area, facilitating broad-spectrum adsorption capabilities for various dyes and drugs. The aerogel achieved impressive adsorption capacities of 175.29 and 75.73 mg/g for cationic methylene blue and Rhodamine B dyes, and 106.33 and 93.29 mg/g for anionic methyl orange and Congo red dyes, as well as 86.25 mg/g for tetracycline hydrochloride, surpassing other reported biomass-based aerogels. Furthermore, it demonstrated effective decolorization ability for wastewater containing mixed dyes. Notably, it exhibited excellent recycling and regeneration properties, maintaining a high removal rate after multiple cycles of adsorption–desorption. The adsorption process of dye/drug by the aerogel followed Langmuir’s monomolecular layer adsorption model, exhibiting spontaneous, endothermic, and disorder-increasing behavior in alignment with the pseudo-second-order kinetic model. This study presents an efficient biomass-based aerogel for the removal of organic pollutants from wastewater.

Recycling Organic Dyes within the Metal-Organic Framework for Photothermal Conversion.

The pursuit of a straightforward method to recycle organic dyes from effluents and repurpose them into valuable materials represents a highly sought-after yet huge challenge within the realms of chemistry, environment, and materials science. In this context, we employ a host-guest strategy that leverages the recycling of the rhodamine B molecule within the porous structure of a metal-organic framework to facilitate photothermal conversion. This achievement is realized through the electrostatic interaction, which then gives rise to remarkable selectivity and unparalleled uptake capacity for the cationic rhodamine B molecule. Capitalizing on this approach, the application of a columnar device and membrane technology for efficiently trapping rhodamine B molecules becomes feasible. On account of the aggregation effect resulting from the confined pore structure of the host matrix, the fluorescence emission of the encapsulated RhB molecules is significantly reduced, which consequently enhances the photothermal performance of the hybrid material through nonradiative transition. Moreover, the photothermal conversion achieved showcases a myriad of high-performance applications, including bacterial inhibition against Escherichia coli and seawater desalination.

Aerosol-assisted fabrication of mesoporous CeO2 nanoparticles for cargo controlled delivery application

This study presents a spray pyrolysis technique for fabricating mesoporous cerium oxide nanoparticles (MCNs) with tunable properties. The MCNs were extensively characterized by their morphology, crystallinity, optical properties, and surface area through transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Raman spectroscopy, UV−vis spectroscopy, and BET adsorption isotherms. We manipulated synthesis parameters to tailor these characteristics, and subsequently evaluated the ability of MCNs to load and release the cationic probe Rhodamine 6G, demonstrating their responsiveness to pH variations. The particles showed high entrapment efficiency (up to 40 %), pH-responsive release, and pore-size-dependent release performance. Additionally, the biocompatibility of MCNs was confirmed by assessing their impact on the viability of HEK293 cells. The findings indicate that the fabricated MCNs hold promise for targeted nano-therapeutic applications, particularly within acidic microenvironments such as tumor sites.

Adsorption of Rhodamine B, methyl Orange, and phenol separately in aqueous systems by magnetic activated carbon: Optimization by central composite design

In the current study, a novel magnetic activated carbon was synthesized for efficient removal of both anionic methyl orange, cationic Rhodamine B and Phenol fromcontaminatedwater. The adsorbent was characterized by different technique. The investigation of the adsorption properties of magnetic activated carbon was studied by central composite design (CCD) coupled with response surface methodology (RSM). The optimal conditions were established as follows: dye concentration of Coat 30 mg/L, dosage at 0.8 g/L, and pH of the adsorbate solution adjusted to 4.5. The different kinetic and isotherm models were applied to fit the experimental results, and it was observed that the Pseudo-second-order kinetics and Langmuir adsorption isotherm were the best-fitted models. The maximal monolayer adsorption capacities of the adsorbent were found to be 101, 218 and 135 mg/g for phenol, methyl orange, and rhodamine B, respectively. The synthesized MAC had outstanding durability and reusability, as seen by the removal rate that persisted over 80 % following four adsorption-oxidation cycles.The advantages of facile synthesis, cost-effectiveness, non-toxicity, strong adsorption capabilities for methyl orange, Rhodamine B and Phenol, and easy separability with an external magnetic field make magnetic activated carbon novel.

Accessing the Potential of Bismuth Oxide Nanosheets for an incredible revelation in the removal of contamination in water bodies

<p>Water contamination is a pressing global issue with far-reaching environmental, health, and socio-economic consequences. As the demand for clean water intensifies, researchers are exploring innovative nanomaterials to develop efficient and sustainable water treatment technologies. The Bismuth oxide (Bi2O3) nanosheets were synthesized using a sustainable approach comprising Moringa oleifera seed extract as a biological capping and reducing agent. Analytical techniques were utilized to inspect the prepared nanosheets' crystalline, morphological, and optical characteristics. The optical properties, including light absorption and bandgap width, were investigated using UV-visible spectroscopy using a bandgap energy of 4.65 eV. In addition, the nanosheet's ability to degrade cationic malachite green and Rhodamine 6G dye and anionic eosin yellow and reactive black dyes by photocatalysis was evaluated. The degradation of cationic and anionic dyes was characterized by nanocatalysis using UV-visible spectroscopy and a pseudo-first-order kinetics model. The pseudo-first-order degradation kinetic rate of malachite green and Rhodamine 6G was determined to be 3.46 and 3.20 X 10-2 min-1, indicating that the prepared nanosheets effectively initiate this dye's degradation. The results showed dye degradation was more effective at cationic dyes than anionic dyes.</p>

One‐Step Synthesis of Thiol‐Functional Mesoporous Silica Nanospheres and Selective Removal of Cationic Dyes

AbstractThe surface characteristics of nanoparticles have a huge impact on adsorption effects. In this paper, thiol‐functional mesoporous silica nanospheres (MSNs−SH) are successfully prepared through simple one‐step hydrolysis and co‐condensation of tetraethyl orthosilicate and (3‐mercaptopropyl) triethoxysilane with hexadecyltrimethylammonium bromide and sulfobetaine 12 as dual‐template. The obtained MSNs−SH have high surface area (1260 m2 g−1), accessible mesopores (2.2 nm), great pore volume (1.7 cm3 g−1), and uniform adjustable diameter (90 nm). Furthermore, the diameter and pore‐size of MSNs−SH can be controlled via adjusting the ethanol content in the synthesis system. MSNs−SH exhibit a fast adsorption kinetics, marked adsorption capacity of cationic rhodamine B (RB 534.2 mg g−1), and remarkable selective adsorption for cationic dyes. Theoretical analysis reveals the adsorption behavior of RB on MSNs−SH follows the Langmuir isotherm models and pseudo‐second‐order kinetic. Additionally, the thermodynamic results indicate that the adsorption process is a spontaneous process driven by temperature. The results demonstrate that MSNs−SH are greatly potential for effectively removing cationic dyes from wastewater, with the advantages of simple preparation, high adsorption performance and perfect selectivity.

Carbon encapsulated ZnO nanoplates for efficient removal of organic dyes from aqueous medium by adsorption: Role of organic ligand and calcination temperature

Water pollution by organic dyes poses great challenge to the environment as well as living organisms. Herein, we have fabricated nanoplates of ZnO in carbon matrix by controlled calcination of zinc-metal organic frameworks (Zn-MOFs) and used as adsorbents for efficient removal of organic dyes from water. Zn-MOF of phthalic acid and 5-nitrophthalic acid produced nanoplates of ZnO (ZnO-C and ZnO-NC) in carbon matrix without and with nitrogen doping. The fabricated hybrid nanostructures were characterized using PXRD, FTIR, BET, TGA, HR-SEM, HR-TEM and XPS analysis. Both ZnO-C and ZnO-NC showed high adsorption of cationic dyes (crystal violet (CV), methylene blue (MB) and Rhodamine B (Rh B)) compared to anionic dyes (methyl orange (MO) and Eosin yellow (EY)). Nitrogen doped ZnO-NC exhibited relatively higher percentage of dyes removal (99 %) compared to ZnO-C. Interestingly, ZnO-NC showed high adsorption of MB dye across the pH range from acidic (pH = 3.0) to alkaline (pH = 11.0). The zero-point charge indicated the negative surface charge for ZnO-NC/ZnO-C that facilitated electrostatic interactions between dyes and adsorbents. Adsorption kinetics suggested a pseudo second order model and adsorption isotherm fitted well with the Freundlich model, suggesting heterogenous adsorption with multilayer coverage of dye molecules. The reusability of ZnO-NC showed only slight reduction of adsorption in three successive cycles. Further, ZnO-NC was used as column packing materials for the successful removal of both cationic as well as anionic dyes upon filtration. Thus, the present studies provided insight on the organic ligand structure and calcination temperature of MOFs for transforming them into effective organic dye adsorbent.

Magnetic Magnetite-Graphene Oxide (Fe3O4-GO) Nanocomposites for Removal of Dyes from Aqueous Solution

Magnetic magnetite-graphene oxide (Fe3O4-GO) was synthesized using an in-situ precipitation technique and applied in the adsorption of cationic rhodamine B (RhB) and anionic methyl orange (MO) dyes from aqueous solution. The nanocomposite was characterized by different techniques including FTIR, XRD, Raman, XPS, PPMS, BET, SEM and TEM techniques. Batch adsorption studies were conducted to investigate the effect of solution pH, initial metal ion concentration, adsorbent dosage and contact time. The synthesized Fe3O4-GO exhibited characteristic magnetic properties (saturation magnetization of 34 emu/g) and it separated from aqueous solution with ease through the application of an external magnetic field. The adsorption equilibrium time on the adsorption of RhB and MO onto Fe3O4-GO showed best removal of 99.12% for RhB after 60 min, while MO was removed efficiently after 120 min with a removal efficiency of 97.60%. The adsorption of the azo dyes followed the pseudo-second-order kinetics model with high correlation coefficients (0.99995) for RhB and (0.99925) for MO. Maximum removal of the dye pollutants by occurred at pH 8 for RhB and pH 4 for MO, while the optimal adsorbent dosage was 30 mg. The results showed that adsorption equilibrium data were fitted to Langmuir isotherm model and maximum monolayer adsorption capacities for RhB and MO at 70.64 and 15.94 mgg−1, respectively. The magnetic adsorbents were reused for a maximum of 7 cycles and showed reasonable stability and reproducibility. Furthermore, the results showed that Fe3O4-GO nanocomposite can be used as an effective material in the removal of dyes from wastewater.

A multi-scale computational investigation of cationic dye interaction with rutile TiO2: An interconnected simulation approach

Metal oxides have increasingly been employed for water pollution remediation. In the present investigation, the adsorptive characteristics of three cationic dyes, rhodamine B (RB), safranin O (SO), and methylene blue (MB), on the (110) surface of rutile titanium dioxide in an aqueous milieu were scrutinized. Utilizing Density Functional Theory (DFT), the reactivity of these organic compounds was evaluated by computing parameters such as molecular frontier orbital energies, energy gap (ΔEgap), electronegativity (χ), chemical hardness (η), chemical softness (σ), electrophilicity (ω), nucleophilicity, electron transfer fraction (ΔN), and Fukui indices. Findings demonstrated that RB exhibited superior reactivity and adsorptive capacity in comparison to MB and SO. Self-Consistent Charge Density-Functional Tight-Binding (SCC-DFTB) simulations revealed that RB engaged in the most potent interactions with the TiO2(110) surface, with interaction energies following the sequence RB (−1.12 eV) > MB (−1.07 eV) > SO (−1.01 eV). Furthermore, the most energetically favorable adsorption configurations for these dyes were elucidated through Molecular Dynamics (MD) simulations. Adsorption energies calculated via MD simulations corroborated that the TiO2 (110) surface possessed high adsorptive capabilities for these cationic dyes, particularly a stronger affinity for RB. The study provides comprehensive insights into the molecular-level interactions between cationic dyes and rutile TiO2, thereby contributing valuable information for the optimization of metal oxide-based water pollution treatment technologies.

Preparation of self-standing ultra-thin three-dimensional covalent organic frameworks by interfacial polymerization for dye separation

Three-dimensional covalent organic frameworks (3D COFs) have garnered considerable attention in the adsorption of small molecules owing to their unique 3D pore structure and easily modifiable functional group sites. However, most 3D COFs exhibit lattice interpenetration, making the membrane fabrication process difficult. Most 3D COFs are prepared as powders using solvothermal methods, which severely limits their application in material separation. Therefore, self-supporting 3D COFs membranes were fabricated using room-temperature interfacial polymerization, a low-energy method. Traditional alkane/water interfacial polymerization methods have disadvantages such as poor water solubility of the monomer, volatile solvents, and low crystallinity. Herein, an imine-linked, self-standing, 3D COFs membrane with an ultrathin layer was engineered at the alkane/ionic liquid interface. Owing to the improved crystalline structure, which exposed a large number of imine-linked sites within a 3D pore channel, the constructed 3D COFs membrane exhibited a high Brunauer–Emmett–Teller surface area of 1061.4 m2·g−1 and high water flux of approximately 76 L·m−2 h−1 bar−1 and demonstrated excellent rejection rates of 97.76% and 95.36% for two cationic dyes, rhodamine B and methylene blue, respectively. The membrane exhibited high rejection rates after seven testing cycles. This study reveals the great potential of self-standing 3D COFs membranes as dye separation.

Charge-Selective Photocatalytic Degradation of Organic Dyes Driven by Naturally Occurring Halloysite Nanotubes

This study explores the use of Halloysite NanoTubes (HNTs) as photocatalysts capable of decomposing organic dyes under exposure to visible or ultraviolet light. Through a systematic series of photocatalytic experiments, we unveil that the photodegradation of Rhodamine B, used as a model cationic dye, is significantly accelerated in the presence of HNTs. We observe that the extent of RhB photocatalytic degradation in 100 min in the presence of the HNTs is ~four times higher compared to that of bare RhB. Moreover, under optimized conditions, the as-extracted photodegradation rate of RhB (~0.0022 min−1) is comparable to that of the previously reported work on the photodegradation of RhB in the presence of tubular nanostructures. A parallel effect is observed for anionic Coumarin photodegradation, albeit less efficiently. Our analysis attributes this discrepancy to the distinct charge states of the two dyes, influencing their attachment sites on HNTs. Cationic Rhodamine B molecules preferentially attach to the outer surface of HNTs, while anionic Coumarin molecules tend to attach to the inner surface. By leveraging the unique properties of HNTs, a family of naturally occurring nanotube structures, this research offers valuable insights for optimizing photocatalytic systems in the pursuit of effective and eco-friendly solutions for environmental remediation.

Rhodamine B Hazardous Dye Removal via Adsorption Using Hg(II) Coordination Polymer

Herein, we have reported the Hg(II) coordination polymer ,(Hg-CP), formulated {[Hg(L)](Cl2)](CH3CN)2}n, behaved as adsorbent against Rhodamine B dye stuff. UV-Vis absorption spectroscopy was used to conduct dye adsorption investigations on coordination polymers. Adsorption experiments were carried out in acidic (pH=3) and neutral (pH=6) media and the results showed that the compound removed the cationic Rhodamine B from water. In acidic media, the adsorption capacity of the Hg-CP was more than neutral media. Also, Hg-CP could selectively adsorb Rhodamine B dye from the Rhodamine B/Methyl orange dye mixture. The colour of the Hg-CP was white before adsorption, whereas it changed after adsorption as Rhodamine B adhered to the surface of Hg-CP.

Sonochemical fabrication of S-scheme Bi2O2CO3/g-C3N4 heterojunction for enhanced photocatalytic destruction of rhodamine B and tetracycline pollutants under natural solar radiations

Photocatalysis is a promising low cost green technology to efficiently mineralize refractory contaminants from wastewater. In this novel research, S-scheme Bi2O2CO3/g-C3N4 heterojunctions containing (0-25) wt % Bi2O2CO3 were sonochemically fabricated for mitigation of hazardous rhodamine B dye and tetracycline antibiotic under sunlight radiations of 900 W power. The physicochemical properties of the solid specimen were explored by photoluminescence [PL], diffuse reflectance spectrum [DRS], X-ray diffraction [XRD], Mapping, high resolution transmission electron microscope [HRTEM], selected area electron diffraction [SAED], N2–adsorption–desorption isotherms and X–ray photoelectron spectroscopy [XPS] techniques. As elucidated by HRTEM analysis, 15 wt% of spherical Bi2O2CO3 nanoparticles of 12 nm size were deposited on g-C3N4 of 40 m2/g surface area at nearly equidistant from each other. The point of zero charge of g-C3N4 sheets was shifted from pHPZC 6.2 to pHPZC 4.8 with incorporation of 15 wt % Bi2O2CO3 revealing the production of negatively charged surface that strongly destructed cationic rhodamine B dye. The rate of photocatalytic degradation of rhodamine B dye for heterojunction containing 15 wt% Bi2O2CO3 was 0.0168 min−1 which is three fold higher than that of pristine g-C3N4 nanosheets. The radical scavengers experimental results revealed that superoxide radicals and positive holes are the main reactive species in the degradation process. The exceptional photocatalytic reactivity emerged from construction of S-scheme heterojunction with auspicious electron-hole pair separation and transportation electron-hole pairs and significant redox power.

Assessment of water purification by IRMOF-1 based on rGO as a new nanoengineered adsorbent: Insights from adsorption mechanism

The main challenge in the use of synthetic dyes and microplastics is their release into water resources, which has adverse effects on human health and the ecosystem. Hence, adsorption removal has been considered an efficient treatment method for pollution remediation from wastewater and industrial effluents. Metal-organic framework/graphene oxide composites can be effectively used for wastewater treatment. In the present study, the uptake mechanism of the cationic dyes, Methylene Blue (MB) and Rhodamine B (RhB), as well as Polyurethane (PU) microplastic by IRMOF-1 based on reduced graphene oxide (IRMOF-1/rGO) nanocomposite was comprehensively evaluated using molecular dynamics (MD) simulation. The contaminant molecules can be adsorbed on the designed nanocomposite to some extent, and which adsorbent exhibits an obvious preference for removing MB over RhB/PU and selectivity. In the case of cationic dyes, the accumulation of textile molecules is observed near the surface of reduced graphene oxide, whereas the metal-organic framework component illustrates a significant uptake capacity for PU microplastic. The tendency of PU microplastics to form a self-organized pattern is noticed in the PU@IRMOF-1/rGO system, but this tendency is less with the coexistence of MB in the mixed system. Increasing the dispersion of microplastic in the mixed system leads to an enhancement in the solvent-accessible surface area of PU from 40.60 nm2 in the individual system to 46.50 nm2 in the mixed system, respectively. It is found that the π-π conjugation, pore-filling effect, van der Waals, and electrostatic interactions govern the water purification mechanism by designed nanocomposite. This work gives a more detailed insight into the use of IRMOF-1@rGO nanocomposite as an effective technology for the decontamination of toxic dyes and microplastics from wastewater.