MB Molecules Research Articles

Characteristics and Methylene Blue Adsorption Capacity of Pyrochar Derived from Lemongrass Residue

In this study, the lemongrass essential oil distillation residue (LR) was the first pyrolyzed under air-controlled conditions at 500 °C for 1 hour (B500), followed by activation through alkali treatment under ultrasonic conditions at 70-80 °C for 3 hours (B5KOH). B5KOH displayed a porous architecture with heightened surface area, 79.90 m2/g, twice the specific surface of B500 material; and carbon content elevated to 87.99%. The material contained some organic functional groups such as C=O, C=C, and C-O-C. The B5KOH sample exhibited the most effective MB uptake at pH 8, achieving adsorption equilibrium within a brief timeframe of approximately 30 – 50 minutes across a concentration spectrum of MB ranging from 5 to 500 mg/L at material loadings of 1-10 g/L, qm is 74.44 mg/g. The material demonstrated substantial recyclability, maintaining nearly consistent adsorption efficiency through the fifth cycle (decreasing marginally from 96.69% to 95.13%). Experimental adsorption conformed to the Freundlich isotherm adsorption model and proceeds via a second-order kinetic model. The adsorption phenomenon was spontaneous, primarily driven by physical interactions between the B5KOH and MB molecules. Overall, lemongrass-derived pyrochar exhibited considerable promise as an adsorbent material for mitigating MB pollution.

Porphyrin like porous fullerene functionalized with Ga as an effective adsorbent for the removal of methylene blue from wastewater effluent

Removal of dyes is a significant aspect of environmental remediation to ensure clean water and atmosphere. In this study, we report Ga decorated porphyrin like porous fullerene (Ga@C24N24) for effective removal of cationic dye (methylene blue) using density functional theory calculations. The calculations show that the Ga are strongly anchored at the surface of the C24N24 system with stronger binding energies and larger positive charges. The molecular dynamics simulations evince that the Ga@C24N24 are thermally stable and withstand high temperatures as 500K. The application of Ga@C24N24 as adsorbent for the removal of MB dye shows that the dye could strongly adsorbed over the Ga@C24N24 surface with stronger electrostatic covalent bonds and larger adsorption energies (-2.71 and -1.89 eV for MB@Ga-C24N24 from N site and S site) compared to bare C24N24 system. The electron density difference, partial density of states, and atom in molecule analysis give evidence of the presence of stronger electrostatic covalent bonds between the Ga@C24N24 and MB. This stronger bonding leads to the chemisorption of MB over the Ga@C24N24 surface. The maximum uptake capacity analysis shows that the studied adsorbent can successfully adsorbed 6MB molecules. The solvation effect decreases the desorption time of the MB molecules from Ga@C24N24. These results show that this study will help the experimentalists to explore the Ga@C24N24 system as a new metalloid doped adsorbent for the removal of toxic pollutants from wastewater.

A self-powered photoelectrochemical aptasensor based on target response and Ag-CdIn2S4 photosensitive material for ultrasensitive detection of prostate-specific antigen

In this study, Ag-CdIn2S4 was selected as a photosensitive material and combined with the zeolite imidazole frame-90 encapsulated methylene blue (ZIF-90@MB) to establish a controlled release system. On that basis, a self-powered photoelectrochemical (PEC) aptasensor was constructed based on target responses to realize the highly sensitive detection of prostate-specific antigen (PSA). The self-powered sensing method was employed to effectively avoid interference from other oxidizing/reducing substances in the system and improve the accuracy of the detection method. The band gap of CdIn2S4 was adjusted by Ag doping, and the visible light absorption capacity and photoelectric conversion efficiency of the material were improved by the local surface plasmon resonance (LSPR) effect of metal Ag. The ZIF-90 porous material was used as a carrier, the MB photosensitizer as a signal molecule was loaded in the ZIF-90 pore channel. The PSA aptamer (PApt) was attached to the ZIF-90@MB surface to form a simple biological gate. In the presence of the PSA, the recognition interaction between PApt and PSA made the biological gate open, then many MB molecules were released from ZIF-90 and enhanced the photocurrent signal. Under the optimal experimental conditions, the linear range of the sensor was 0.005 ∼ 50 ng mL−1, and the detection limit was 2.35 pg mL−1. The accurate determination of PSA in human serum was achieved, which provided a novel sensing strategy for the early diagnosis of clinical biomarkers.

Fabrication of used-tea embedded alginate beads for cationic dye remediation: Synergistic effect of surface adsorption and intraparticle diffusion

Water pollution has become a major concern due to high industrialization and poor waste management policies. Recently, organic contaminants such as dyes are severely influencing environmental conditions and therefore, it must be employed to efficient treatment processes before discarding in waterbodies. In this work, used-tea embedded alginate beads were fabricated as a novel adsorbent for removing a cationic dye (methylene blue, MB). The physical properties of fabricated beads were investigated and also characterized using field emission scanning electron microscope (FESEM), energy dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The highest MB removal efficiency of about 97.38 ± 1.84% was obtained at optimized pH 7 and 25 °C. The adsorption capacity (qe) increased with MB concentration and the pseudo-second-order model exhibited excellent fit. MB adsorption comprises rapid surface adsorption (initial 5 min) and slow inter-particle diffusion (after 5 min). Supporting the Langmuir isotherm indicated the formation of a monolayer of MB on the surface of the beads and the calculated maximum adsorption capacity (qm) was 421.94 mg/g. Negative ΔG (-7.25 kJ/mol) and ΔH (-52.67 kJ/mol) reveal MB removal as a spontaneous and exothermic process. Positive entropy change of ΔS (152.05 J/mol) states increased randomness, facilitating promoted affinity of beads for free MB molecules. A removal efficiency of about 90.40 ± 2.91% was obtained up to 3rd cycle of its reuse, which further decreased to 67.11 ± 1.72% during 5th cycle. The MB adsorption mechanism was investigated by comparing the physiochemical and morphological characteristics of beads before and after MB removal.

Superior Drug Delivery Performance of Multifunctional Bilosomes: Innovative Strategy to Kill Skin Cancer Cells for Nanomedicine Application.

Numerous failures in melanoma treatment as a highly aggressive form of skin cancer with an unfavorable prognosis and excessive resistance to conventional therapies are prompting an urgent search for more effective therapeutic tools. Consequently, to increase the treatment efficiency and to reduce the side effects of traditional administration ways, herein, it has become crucial to combine photodynamic therapy as a promising therapeutic approach with the selectivity and biocompatibility of a novel colloidal transdermal nanoplatform for effective delivery of hybrid cargo with synergistic effects on melanoma cells. The self-assembled bilosomes, co-stabilized with L-α-phosphatidylcholine, sodium cholate, Pluronic® P123, and cholesterol, were designated, and the stability of colloidal vesicles was studied using dynamic and electrophoretic light scattering, also provided in cell culture medium (Dulbecco's Modified Eagle's Medium). The hybrid compounds - a classical photosensitizer (Methylene Blue) along with a complementary natural polyphenolic agent (curcumin), were successfully co-loaded, as confirmed by UV-Vis, ATR-FTIR, and fluorescent spectroscopies. The biocompatibility and usefulness of the polymer functionalized bilosome with loaded double cargo were demonstrated in vitro cyto- and phototoxicity experiments using normal keratinocytes and melanoma cancer cells. Thein vitrobioimaging and immunofluorescence study upon human skin epithelial (A375) and malignant (Me45) melanoma cell lines established the protective effect of the PEGylated bilosome surface. This effect was confirmed in cytotoxicity experiments, also determined on human cutaneous (HaCaT) keratinocytes. The flow cytometry experiments indicated the enhanced uptake of the encapsulated hybrid cargo compared to the non-loaded MB and CUR molecules, as well as a selectivity of the obtained nanocarriers upon tumor cell lines. The phyto-photodynamic action provided 24h-post irradiation revealed a more significant influence of the nanoplatform on Me45 cells in contrast to the A375 cell line, causing the cell viability rate below 20% of the control. As a result, we established an innovative and effective strategy for potential metastatic melanoma treatment through the synergism of phyto-photodynamic therapy and novel bilosomal-origin nanophotosensitizers.

A highly sensitive ratiometric electrochemical aptasensor for prostate specific antigen detection based on toehold-mediated strand displacement reaction

In this work, a novel ratiometric electrochemical aptasensor was designed for prostate specific antigen (PSA) detection based on toehold-mediated strand displacement reaction (TMSDR). For PSA detection, PSA could bind with the aptamer sequence in hairpin probe 1 (HP1), and HP1/PSA complex was obtained. Then, in the presence of S3 DNA, HP1/PSA could trigger two TMSDR processes by hybridizing with Fc-S2/S1 double-stranded DNA, which would generate a large amount of Fc-S2 and recycle HP1/PSA. This enabled the hybridization of Fc-S2 with methylene blue labeled thiolated hairpin probe 2 (MB-HP2) immobilized on the electrode surface, causing MB molecules away from the electrode and Fc close to the electrode. Thus, with the increasing PSA concentrations, the current of MB (IMB) decreased and the current of Fc (IFc) increased. The ratio of IFc/IMB was shown to be linear with the logarithm of PSA concentration from 1 pg mL−1 to 100 ng mL−1, with a detection limit of 0.28 pg mL−1. In addition, the aptasensor had good specificity, reproducibility, repeatability, and stability for PSA detection, and was successfully applied to spiked diluted human serum samples.

Electrochemiluminescence Analysis of Multiple Glycans on Single Living Cell with a Closed Bipolar Electrode Array Chip.

The profiling of multiple glycans on a single cell is important for elucidating glycosylation mechanisms and accurately identifying disease states. Herein, we developed a closed bipolar electrode (BPE) array chip for live single-cell trapping and in situ galactose and sialic acid detection with the electrochemiluminescence (ECL) method. Methylene blue-DNA (MB-DNA) as well as biotin-DNA (Bio-DNA) codecorated AuNPs were prepared as nanoprobes, which were selectively labeled on the cell surface through chemoselective labeling techniques. The individual cell was captured and labeled in the microtrap of the cathodic chamber, under an appropriate potential, MB molecules on the cellular membrane underwent oxidation, triggering the reduction of [Ru(bpy)3]2+/TPA and consequently generating ECL signals in the anodic chamber. The abundance of MB groups on the single cell enabled selective monitoring of both sialic acid and galactosyl groups with high sensitivity using ECL. The sialic acid and galactosyl content per HepG2 cell were detected to be 0.66 and 0.82 fmol, respectively. Through comprehensive evaluation of these two types of glycans on a single cell, tumor cells, and normal cells could be effectively discriminated and the accuracy of single-cell heterogeneous analysis was improved. Additionally, dynamic monitoring of variations in galactosyl groups on the surface of the single cell was also achieved. This work introduced a straightforward and convenient approach for heterogeneity analysis among single cells.

Simultaneous removal of anionic and cationic dyes on quaternary mixtures by adsorption onto banana, orange and pomegranate peels

Disposal of untreated wastewater released by industries using dyes, causes serious damage to aquatic life and to the ecosystem in general. Both physical and chemical methods have been used for the removal of these dyes from wastewater; among them, adsorption has been found to be a very efficient technique. In this study, the ability to simultaneously remove cationic (MB) and anionic dyes (RR120, RB5 and RBBR) from a quaternary mixture solution by using zero-cost materials as banana, orange and pomegranate peels, was investigated. The optimal removal rates were achieved at pH 2.0 and a dose of 6.0 g/L. The comparative results of natural adsorbents on dye removal, separately and simultaneously in solution showed that MB adsorption on banana and orange peels was augmented from 89 to 96 and 43 to 87%, respectively, in the presence of anionic dyes (synergistic effect). On the other hand, a competitive effect was determined, mainly between anionic dyes, resulting in a decrease in their respective percentage. Banana peels were selected as the adsorbent material for further study in a quaternary dye mixture containing all dyes. Parameters affecting dye adsorption such as pH solution, initial concentration of dyes, contact time and temperature were examined. Based on the experimental results, two mechanisms for interactions were proposed: (a) the cationic MB molecules are connected to the negatively charged anionic dyes or (b) electrostatic attractions occurred among cationic MB molecules and negatively charged anionic dyes in the solution enhancing the adsorption efficiency. Kinetic experiments showed that equilibrium for anionic dyes reached at around 180 min (3 h), and for MB was reached much faster, at 30 min; 87% of 20 mg/L was found to be removed in just 5 min. Langmuir isotherm model and pseudo-second-order kinetic model were best fitted to the experimental results. According to thermodynamics the spontaneous nature of their adsorption was confirmed.

Electronic Structure and Chemical Bonding of the First-, Second-, and Third-Row-Transition-Metal Monoborides: The Formation of Quadruple Bonds in RhB, RuB, and TcB.

Boron presents an important role in chemistry, biology, and materials science. Diatomic transition-metal borides (MBs) are the building blocks of many complexes and materials, and they present unique electronic structures with interesting and peculiar properties and a variety of bonding schemes which are analyzed here. In the first part of this paper, we present a review on the available experimental and theoretical studies on the first-row-transition-metal borides, i.e., ScB, TiB, VB, CrB, MnB, FeB, CoB, NiB, CuB, and ZnB; the second-row-transition-metal borides, i.e., YB, ZrB, NbB, MoB, TcB, RuB, RhB, PdB, AgB, and CdB; and the third-row-transition-metal borides, i.e., LaB, HfB, TaB, WB, ReB, OsB, IrB, PtB, AuB, and HgB. Consequently, in the second part, the second- and third-row MBs are studied via DFT calculations using the B3LYP, TPSSh, and MN15 functionals and, in some cases, via multi-reference methods, MRCISD+Q, in conjunction with the aug-cc-pVQZ-PPM/aug-cc-pVQZB basis sets. Specifically, bond distances, dissociation energies, frequencies, dipole moments, and natural NPA charges are reported. Comparisons between MB molecules along the three rows are presented, and their differences and similarities are analyzed. The bonding of the diatomic borides is also described; it is found that, apart from RhB(X1Σ+), which was just recently found to form quadruple bonds, RuB(X2Δ) and TcB(X3Σ-) also form quadruple σ2σ2π2π2 bonds in their X states. Moreover, to fill the gap existing in the current literature, here, we calculate the TcB molecule.

Exploring the impact of incubation times and concentrations of self-assembled monolayers on electron transfer in biosensing

This study investigates the impact of different incubation times and concentrations of a self-assembled monolayer (SAMs) of 3-mercaptopropionic acid (MPA) on the rate of electron transfer in redox processes. The aim is to understand how these parameters can affect the sensitivity and efficiency of biosensors based on direct electron transfer in redox proteins. Through a series of experiments, different incubation times and concentrations of MPA were examined to determine their impact on the electron-transfer rate. Using methylene blue MB molecules as a model system and employing the EC-SPR technique, the reflectance differences (ΔR) between the reduced and oxidized states of MB were analyzed, serving as an indicator of the electron transfer rate. The results revealed significant variations in the rate depending on the incubation times and concentrations of the MPA. It was determined that a combination of 1 mM MPA concentration and 6-hour incubation time provided optimal conditions for maintaining a significant (ΔR). These findings have important implications for optimizing sensor surfaces in biosensors based on direct electron transfer in redox proteins.

Flexible structural regulation of montmorillonite through intercalation by zwitterionic surfactants for effective removal of methylene blue

Herein, the structural evolution of organo-montmorillonite (organo-Mt) after the intercalation of zwitterionic surfactants with different alkyl chains was investigated and linked the adsorption behavior of cationic dye (methylene blue, MB). The zeta potential of Mt before and after intercalation showed very small change. While the modification had a significant effect on hydrophilicity of Mt owing to introducing the alkyl chains. The interlayer spacing of Mt was determined by X-ray diffraction, which was used to analyze the arrangement patterns of zwitterionic surfactants in the interlayer according to the molecules size. The relationship between the structural characteristic of organo-Mt and adsorption changes indicated that the paraffin-type arrangement of zwitterionic surfactants and overlong alkyl chain were unfavorable to adsorption. The introduction of appropriate hydrophobic structure endowed high dye adsorption capacity, evidencing the importance of structure regulation of Mt in adsorption. The adsorption of MB by organo-Mt was a spontaneous exothermic process, in which MB molecules were covered on organo-Mt in a monolayer. Compared with Na-Mt, the adsorption capacity of 0.6CEC BS-10/Mt (lateral monolayer arrangement of BS-10 in the interlayer of Mt) could be increased by about 20%. Overall, this work provided valuable guidance for the modification (more types of modifiers) and utilization (adsorbents, nanomaterials, etc.) of Mt in different fields.

Highly sensitive detection of cationic pollutants on molybdenum carbide (MXene)/Fe2O3/Ag as a SERS substrate

Recent studies reported that the two-dimensional transition-metal carbides (MXenes) present promising results for surface-enhanced Raman spectroscopy (SERS) application, permitting sensitive detection of analyte molecules thanks to rich surface chemistries, surface plasmon resonances, and electrical features. However, Mxene materials, especially Mo-based ones, still suffer from low concentrated sensing activity and lack specific sensing suited to surface chemistries. To overcome those issues, for the first time, we propose a simple and scalable approach to fabricate Mo2CTx/Fe2O3/Ag (MFA) hybrid nanostructure via the hydrothermal treatment of MXene and Fe2O3, and subsequent in-situ decorated of Ag NPs via seed-mediated growth processes. As-prepared MFA presents a 1 × 10−9 M detection limit with a 1.46 × 106 enhancement factor for cationic MB molecules. Here, in addition to the contribution of the electromagnetic enhancement mechanism due to the presence of Ag, the chemical enhancement mechanism also comes into play as a result of the specific binding of the cationic molecule, MB, to the negatively charged MXene surface. This result is also observed for harmful cationic molecules found in wastewater such as CTAC and arsenic. MFA exhibits a low detection limit for CTAB, where a very low concentration of 0.075 M was achieved probably owing to its cationic character. Last but not least, the MFA hybrid nanostructure shows promising results for arsenic detection in tap water with 10 μg/L. Overall, an as-prepared MFA is a promising option for creating a SERS-active surface that can be customized for particular uses, due to its adjustable surface chemistries and elevated charge carrier densities, while also being low-cost and simple to manufacture.

Immobilization of ZnO:Ga nanocrystals in a polystyrene/cellulose matrix: A novel hybrid nanocomposite photocatalyst for future photo energy application

This article reports a portable, flexible gallium doped zinc oxide/polystyrene/cellulose (GZO/PSC) nanocomposite and the development of a hybrid material for various applications primarily in water treatment and renewable energy. With respect to a green technology, our nanocomposite can be easily eliminated from the pollution mixture, after using. A complete morphological, structural, mechanical, chemical, and optical characterization was made using different analysis techniques. Secondly, catalytic activities for photocatalytic and sonocatalytic degradation were evaluated by decolorizing methylene blue/orange in an aqueous solution under dark, light, and ultrasonic exposure. The synthesized GZO NPs and GZO/PSC hybrid nanocomposite showed a high decolorization efficiency in a short time. These samples destroyed the MB dye molecule (98 and 96 ± 1%) in just 10 and 45 min respectively, under UVA irradiation. Just 7 min simultaneous irradiation of both UVA light/ultrasonic resulted in 95% destruction of MB molecules for GZO NPs (neat fillers). Our results show that the GZO/PS and GZO/PSC hybrid films (Ga:ZnO@PCS) can be easily used in both the field of flexible luminescent devices and water treatment, respectively. At the same time, no photocatalyst remained in the reaction system after wastewater treatment. This simple approach can be upscaled for industrial use.

Enhanced photocatalytic and SERS performance of Ag nanoparticles functionalized MoS2 nanoflakes

We report the preparation of Ag nanoparticles functionalized MoS2 nanoflakes by using the chemical reduction method followed by the hydrothermal method. Field emission scanning electron microscopy and elemental mapping reveals the uniform functionalization of Ag nanoparticles with MoS2 nanoflakes. High density of Ag plasmonic nanoparticles onto MoS2 nanoflakes demonstrates tremendously improved charge separation behavior in Ag–MoS2 nanohybrids. Photodecomposition capability of plasmonic Ag–MoS2 nanohybrids was explored by the decomposition of industrial pollutant molecules, showing a direct correlation between the Ag content over the MoS2 surface with their photodecomposition ability. The SERS-based detection profiles of the plasmonic were investigated by the ultra-low detection of MB molecules.The Ag–MoS2 nanohybrids SERS substrate manifests the detection of MB molecules solution up to a concentration of 10−9 M with an enhancement factor of 107. In the current study, we proposed and elucidated the probable efficient charge transfer mechanism for improved photocatalytic behavior and SERS-based sensing performance.

Protective action of graphene oxide against singlet oxygen generation by cosmetic dye methylene blue

Nanohybrid methylene blue/graphene oxide (MB/GO) was prepared via non-covalent functionalization with the focus on spectroscopic characterization of MB molecules adsorbed on GO. Fluorescence was not detected for the MB/GO hybrid which indicates that other competitive fast singlet excited state deactivation process must take place. It was demonstrated by measuring singlet oxygen (1O2) phosphorescence at 1270 nm that MB functionalized with GO does not generate 1O2. Nanosecond transient absorption spectroscopy experiments pointed to a lack of population of triplet state by MB/GO hybrid material. Femtosecond pump–probe experiments revealed much faster dynamics of the singlet excited state of MB/GO in comparison to free MB, which was attributed to the photoinduced electron transfer from MB to GO. Suppressing of the singlet oxygen quantum efficiency by MB upon functionalization to GO might be useful for designing graphene-based dye additives to color cosmetics with a reduced risk of the 1O2 generation on the skin.

Laser-textured Pd-Au hierarchical superhydrophobic micro-arrays for ultralow SERS detection

Ultra-trace identification of the limited quantity of diluted analyte solutions requires the condensation of target analytes utilizing the superhydrophobic analyte enrichment effect and are extremely desirable for improving the detection sensitivity. Herein, the identification of ultra-trace analyte concentrations employing laser-textured palladium-gold (Pd-Au) hierarchical superhydrophobic micro-arrays as surface-enhanced Raman sensors (SMA-SERS) is reported. The double ns-laser fast scanning strategy produces hierarchically arranged micro-strip and micro-pyramidal arrays over the large surface areas composed of nano-scale inter-particle gaps, enabling the numerous three-dimensional plasmonic hot-spots due to the uniform formation of Au nanoparticles' aggregates/clusters. Under the optimized fabrication parameters, the resultant hybrid SMA-SERS sensors exhibit periodic micro-pyramidal arrays with excellent inherent superhydrophobicity (Contact angle, CA∼171°) and consequently superior SERS performance with uniform (RSD∼10%) signal detectability down to the ∼34.2 fM (3.42×10−14 M) MB molecules utilizing analyte enrichment effect. The accumulation of analytes within the smaller dried spots (Contact diameter, CD∼1.13 mm) results in increased spatial density of analytes and subsequently enables the ultra-low detectability of MGO, DTTCI, PA, AN, adenine, and l-tryp molecules down to ∼3.57 pM, 0.34 fM, 0.31 nM, 0.44 µM, 0.25 nM, and 97.7 nM concentrations, respectively. The multiplexed identification of target (AN and adenine) analytes is explored utilizing serial-deposition of analytes and depict the simultaneous detection of target analytes down to ∼10−7 M (AN) and 10−9 M (adenine) concentrations. The double ns-laser fast scanning strategy provides dual-scale surface roughness in the SMA-SERS substrates and offers ultrahigh sensitivity for the identification of the low amount of analytes utilizing the superhydrophobicity-induced analyte enrichment effect.

A mechanism study of methylene blue adsorption on seaweed biomass derived carbon: From macroscopic to microscopic scale

Biomass based active adsorbent can be prepared by activation process to adsorb dyes. In this study, using macroalgae as raw material, the biomass based activated carbon material was prepared by NaOH activation method to adsorb methylene blue. The activated adsorbent with high specific surface area (1238.491 m2 g−1) was characterized by BET, XRD, FTIR and XPS. The effects of impregnation ratio, amount of adsorbent, pH and contact time on the adsorption activity of biochar on MB were evaluated. The adsorption kinetics, molecular dynamics and density functional theory were discussed. The maximum MB removal efficiency of SWAC reached 98.56 % at 30 °C and pH= 5 which is due to its large specific surface area and mesoporous slit structure. MD simulation shows that MB molecules were adsorbed on carbon layer through face-to-face stacking. DFT calculation and subsequent electron structure analysis suggested that a synergistic effect of π-π stacking, cation-π interaction, and electrostatic interaction could help stabilize adsorbed MB molecules. And an excellent adsorption capacity SWAC is due to its graphitic N sites for high electronegativity.

Role of reduced graphene oxide-co-double-doped Fe3O4 nanocomposites for photocatalytic and supercapacitor applications

The present work describes the preparation of Fe3O4 nanoparticles, reduced graphene oxide-doped Fe3O4 nanocomposites and reduced graphene oxide-cobalt double-doped Fe3O4 nanocomposites via a facile co-precipitation technique. The incorporation of reduced graphene oxide and cobalt play a crucial role in the tuning of structural, optical and morphological parameters of Fe3O4 nanoparticles. The supercapacitor performance of the prepared materials is investigated in symmetric two-electrode configuration. The symmetric supercapacitor device fabricated using Fe3O4 nanoparticles, G/F-NCs, and G/Co/F-NCs-based electrodes exhibit specific capacitance values of 94, 168, and 184 F/g at 1 Ag−1. Further, the efficiency of Fe3O4 nanoparticles, reduced graphene oxide-doped Fe3O4 nanocomposites, and reduced graphene oxide-cobalt double doped Fe3O4 nanocomposites as photocatalysts are studied on methylene blue dye. The study reveals that reduced graphene oxide-cobalt double doped Fe3O4 nanocomposites exhibits the highest photocatalytic activity due to their enlarged active sites for the adsorption of MB molecules.

Chitosan-induced self-assembly of montmorillonite nanosheets along the end-face for methylene blue removal from water

In this study, chitosan-induced self-assembly of montmorillonite nanosheets (MMTNS) along the end-face to form the layered and porous structured composite with high adsorption capacity towards MB dye wastewater was investigated. The self-assembly process was driven by the hydrogen-bond interaction among –OH groups distributed along the end-face of MMTNS and –NH2 groups on chitosan (CS) chain, which finally formed the infinite two-dimensional lamellae. This technology remained the exposed adsorption sites on MMTNS surface, and solved the separation issue of spent MMTNS from water, making MMTNS/CS an excellent adsorption material for macromolecular MB dye. The maximum adsorption capacity of MMTNS/CS towards MB reached 243 mg/g, which was achieved via the Na+- exchange, hydrogen-bond and n-π stacking interactions with MB molecules. This work aimed at breaking through the bottleneck of small adsorption capacity of traditional MMT adsorbents, solving the problem of solid-liquid separation of nanosheets, and effectively reducing the adsorption cost, which might guide an important direction for adsorption material design and development in the future.

A novel octamolybdate‐based organic–inorganic hybrid as photo‐Fenton‐like catalyst for degradation of methylene blue

A γ‐Mo8O26‐based organic–inorganic hybrid [Cu2(L)2(γ‐Mo8O26)0.5(H2O)]•H2O (CuLMo8) [L = 5‐(pyrimidyl)tetrazolate] was hydrothermally synthesized and fully characterized by various spectral techniques. In the crystal structure of CuLMo8, the μ2‐bridging γ‐Mo8 anion coordinates with Cu ions to extend into a 2D network. CuLMo8 displayed excellent photo‐Fenton‐like catalyst properties for MB degradation under UV light irradiation. Complete decolorization of MB solution was finished in 5 min, and the degradation rate reached 97.9% in 7 min. The degradation rate of the present system was much higher than that of similar systems in the literature. The synergistic effect of CuLMo8 and H2O2 was the fundamental reason for the high degradation rate. Initial pH value and concentration of MB solution, catalyst dosage, and concentration of H2O2 were the main factors to affect the degradation rate. Hydroxyl (•OH) and superoxide (•O2H/O2•‐) radicals were the major reactive species to degrade MB molecules. Moreover, the total organic carbon (TOC) removal was about 37.5% in 3 h, indicating mineralization and decolorization did not take place at the same time. The possible MB degradation pathway was deduced depending on the data gained. In view of the high catalytic efficiency, repeated use, and no need to adjust the pH value of MB solution, this heterogeneous catalyst might have potential to deal with practical wastewater.