Magnetic hydrochar grafted-chitosan for enhanced efficient adsorption of malachite green dye from aqueous solutions: Modeling, adsorption behavior, and mechanism analysis.

Water pollution by organic dyes is one of the most serious environmental problems worldwide. Malachite green (MG) is considered as one the serious organic dyes which is discharged in wastewater by leather and textile manufacturing plants. MG dye can cause severe hazards to the environment and human health. Therefore, the removal of MG dye from wastewater is very important and essential. This study aims to synthesize a new magnetic hydrochar grafted to chitosan (MWSHC@CS) for the removal of MG dye from the aqueous solutions. Transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area, and Zeta potential analysis were used to characterize the synthesized MWSHC@CS. Batch experiments were conducted to optimize MG dye adsorption conditions, including adsorbent mass, pH, temperature, initial concentration, and contact time. The results revealed that MWSHC@CS had an excellent removal efficiency (96.47 %) for MG dye at the optimum condition (at m: 20 mg, pH: 7.5, t: 420 min, and T: 298 K). Adsorption isotherms outcomes revealed the MG adsorption data were best fit by the Langmuir model with a maximum adsorption capacity (420.02 mg/g). Adsorption kinetics outcomes exhibited that the adsorption process of MG dye fitted well to the Elovich model. The thermodynamic results revealed that the adsorption process was physical, exothermic, and spontaneous. The adsorption mechanisms of MG onto MWSHC@CS were hydrogen bonding, electrostatic interaction, and π-π interactions. Furthermore, MWSHC@CS showed excellent reusability for the removal of MG over five cycles of adsorption-desorption (83.76 %). In conclusion, the study provides a new, low-cost, and effective magnetic nanocomposite based on chitosan as a promising adsorbent for the high-performance removal of MG dye from aqueous solutions.

Ce-doped ZnO nanostructures: A promising platform for NO2 gas sensing.

In this comprehensive study, Ce-doped ZnO nanostructures were hydrothermally synthesized with varying Ce concentrations (0.5%, 1.0%, 1.5%, and 2.0%) to explore their gas-sensing capabilities, particularly towards NO2. Structural characterization revealed that as Ce doping increased, crystal size exhibited a slight increment while band gap energies decreased. Notably, the 0.5% Ce-doped ZnO nanostructure demonstrated the highest NO2 gas response of 8.6, underscoring the significance of a delicate balance between crystal size and band gap energy for optimal sensing performance. The selectivity of the 0.5% Ce-doped ZnO nanostructures to NO2 over other gases like H2, acetone, NH3, and CO at a concentration of 100 ppm and an optimized temperature of 250 °C was exceptional, highlighting its discriminatory prowess even in the presence of potential interfering gases. Furthermore, the sensor displayed reliability and reversibility during five consecutive tests, showcasing consistent performance. Long-term stability testing over 30 days revealed that the gas response remained almost constant, indicating the sensor's remarkable durability. In addition to its robustness against humidity variations, maintaining effectiveness even at 41% humidity, the sensor exhibited impressive response and recovery times. While the response time was swift at 11.8 s, the recovery time was slightly prolonged at 56.3 s due to the strong adsorption of NO2 molecules onto the sensing material hindering the desorption process. The study revealed the intricate connection between Ce-doping levels, structure, and gas-sensing. It highlighted the 0.5% Ce-doped ZnO nanostructure as a highly selective, reliable, and durable NO2 gas sensor, with implications for future environmental monitoring and safety.

Unveiling the potential of PANI@MnO2@rGO ternary nanocomposite in energy storage and gas sensing.

The development of advanced materials for energy storage and gas sensing applications has gained significant attention in recent years. In this study, we synthesized and characterized PANI@MnO2@rGO ternary nanocomposites (NCs) to explore their potential in supercapacitors and gas sensing devices. The ternary NCs were synthesized through a multi-step process involving the hydrothermal synthesis of MnO2 nanoparticles, preparation of PANI@rGO composites and the assembly to the ternary PANI@MnO2@rGO ternary NCs. The structural, morphological, and compositional characteristics of the materials were thoroughly analyzed using techniques such as XRD, FESEM, TEM, FTIR, and Raman spectroscopy. In the realm of gas sensing, the ternary NCs exhibited excellent performance as NH3 gas sensors. The optimized operating temperature of 100 °C yielded a peak response of 15.56 towards 50 ppm NH3. The nanocomposites demonstrated fast response and recovery times of 6 s and 10 s, respectively, and displayed remarkable selectivity for NH3 gas over other tested gases. For supercapacitor applications, the electrochemical performance of the ternary NCs was evaluated using cyclic voltammetry and galvanostatic charge-discharge techniques. The composites exhibited pseudocapacitive behavior, with the capacitance reaching up to 185 F/g at 1 A/g and excellent capacitance retention of approximately 88.54% over 4000 charge-discharge cycles. The unique combination of rGO, PANI, and MnO2 nanoparticles in these ternary NCs offer synergistic advantages, showcasing their potential to address challenges in energy storage and gas sensing technologies.

Colorimetric Detection of Cu2+ and Ag+ Ions Using Multi-Responsive Schiff Base Chemosensor: A Versatile Approach for Environmental Monitoring.

In this study, we have synthesized a novel Schiff base-centered chemosensor, designated as SB, with the chemical name ((E)-1-(((6-methylbenzo[d]thiazol-2-yl) imino)methyl)naphthalen-2-ol). This chemosensor was structurally characterized by FT-IR, 1H NMR, UV-Vis and fluorescence spectroscopy. After structural characterization the chemosensor SB was subsequently employed for the detection of Cu2+ and Ag+, using fluorescence spectroscopy. The chemosensor SB showed excellent ability to recognize the target metal ions, leading to fluorescence enhancement and color change from yellow to yellowish orange for Cu2+ and yellow to radish for Ag+ ions. The detection capabilities of this chemosensor were impressive, showing excellent selectivity and an exceptionally low detection limit of 0.0016 µM for Cu2+ and 0.00389 µM for Ag+. Most notably, our approach enables the quantitative detection both metal ions in different water and soil samples at trace level. This achievement holds great promise for analytical applications and offers significant contributions to the field of chemical sensing and environmental protection.

Iron-modified biochar improves plant physiology, soil nutritional status and mitigates Pb and Cd-hazard in wheat (Triticum aestivum L.).

Environmental quality and food safety is threatened by contamination of lead (Pb) and cadmium (Cd) heavy metals in agricultural soils. Therefore, it is necessary to develop effective techniques for remediation of such soils. In this study, we prepared iron-modified biochar (Fe-BC) which combines the unique characteristics of pristine biochar (BC) and iron. The current study investigated the effect of pristine and iron modified biochar (Fe-BC) on the nutritional values of soil and on the reduction of Pb and Cd toxicity in wheat plants (Triticum aestivum L.). The findings of present study exhibited that 2% Fe-BC treatments significantly increased the dry weights of roots, shoots, husk and grains by 148.2, 53.2, 64.2 and 148%, respectively compared to control plants. The 2% Fe-BC treatment also enhanced photosynthesis rate, transpiration rate, stomatal conductance, intercellular CO2, chlorophyll a and b contents, by 43.2, 88.4, 24.9, 32.5, 21.4, and 26.7%, respectively. Moreover, 2% Fe-BC treatment suppressed the oxidative stress in wheat plants by increasing superoxide dismutase (SOD) and catalase (CAT) by 62.4 and 69.2%, respectively. The results showed that 2% Fe-BC treatment significantly lowered Cd levels in wheat roots, shoots, husk, and grains by 23.7, 44.5, 33.2, and 76.3%. Whereas, Pb concentrations in wheat roots, shoots, husk, and grains decreased by 46.4, 49.4, 53.6, and 68.3%, respectively. Post-harvest soil analysis showed that soil treatment with 2% Fe-BC increased soil urease, CAT and acid phosphatase enzyme activities by 48.4, 74.4 and 117.3%, respectively. Similarly, 2% Fe-BC treatment significantly improved nutrients availability in the soil as the available N, P, K, and Fe contents increased by 22, 25, 7.3, and 13.3%, respectively. Fe-BC is a viable solution for the remediation of hazardous Cd and Pb contaminated soils, and improvement of soil fertility status.

Polyethylene glycol embedded reduced graphene oxide supramolecular assemblies for enhanced room-temperature gas sensors.

Herein, we present the gas-dependent electrical properties of a reduced graphene oxide nanocomposite. The reduced graphene oxide (rGO) was synthesized by reducing GO with sodium borohydride (NaBH4). As-synthesized rGO was dispersed in DI water containing 1, 2, 3, 4, and 5 wt% polyethylene glycol (PEG) to prepare PEG-rGO supramolecular assemblies. The successful preparation of supramolecular assemblies was verified by their characterization using XRD, FESEM, EDS, TEM, FTIR, and Raman spectroscopy. At room temperature, the gas-dependent electrical properties of these supramolecular assemblies were investigated. The results showed that sensors composed of PEG-rGO supramolecular assemblies performed better against benzene and methanol at 3% and 4% PEG, respectively. However, high selectivity and a wide range of activation energies (∼1.64-1.91 eV) were observed for H2 gas for 4% PEG-modified supramolecular assemblies. The PEG-rGO supramolecular assemblies may be an excellent candidate for constructing ultrahigh-performance gas sensors for a variety of applications due to their high sensitivity and selectivity.

Production of Ceramics/Metal Oxide Nanofibers via Electrospinning: New Insights into the Photocatalytic and Bactericidal Mechanisms.

Environmental pollution is steadily rising and is having a negative influence on all living things, especially human beings. The advancement of nanoscience in recent decades has provided potential to address this issue. Functional metal oxide nanoparticles/nanofibers have been having a pull-on effect in the biological and environmental domains of nanobiotechnology. Current work, for the first time, is focusing on the electrospinning production of Zr0.5Sn0.5TiO3/SnO2 ceramic nanofibers that may be utilized to battle lethal infections swiftly and inexpensively. By using characterizations like XRD, FT-IR, FESEM, TEM, PL, and UV-Vis-DRS, the composition, structure, morphology, and optical absorption of samples were determined. The minimum inhibitory concentration (MIC) approach was used to investigate the antibacterial activity. Notably, this research indicated that nanofibers exert antibacterial action against both Gram-positive and Gram-negative bacteria with a MIC of 25 µg/mL. Furthermore, negatively charged E. coli was drawn to positively charged metal ions of Zr0.5Sn0.5TiO3/SnO2, which showed a robust inhibitory effect against E. coli. It was interesting to discover that, compared to pure TiO2, Zr0.5Sn0.5TiO3/SnO2 nanofibers revealed increased photocatalytic activity and exceptional cyclability to the photodegradation of Rhodamine B. The composite completely degrades dye in 30 min with 100% efficacy and excellent (97%) reusability. The synergetic effects of Zr0.5Sn0.5TiO3 and SnO2 may be responsible for increased photocatalytic and bactericidal activity.

Bismuth Vanadate Decked Polyaniline Polymeric Nanocomposites: The Robust Photocatalytic Destruction of Microbial and Chemical Toxicants.

Functional materials have long been studied for a variety of environmental applications, resource rescue, and many other conceivable applications. The present study reports on the synthesis of bismuth vanadate (BiVO4) integrated polyaniline (PANI) using the hydrothermal method. The topology of BiVO4 decked PANI catalysts was investigated by SEM and TEM. XRD, EDX, FT-IR, and antibacterial testing were used to examine the physicochemical and antibacterial properties of the samples, respectively. Microscopic images revealed that BiVO4@PANI are comprised of BiVO4 hollow cages made up of nanobeads that are uniformly dispersed across PANI tubes. The PL results confirm that the composite has the lowest electron-hole recombination compared to others samples. BiVO4@PANI composite photocatalysts demonstrated the maximum degradation efficiency compared to pure BiVO4 and PANI for rhodamine B dye. The probable antimicrobial and photocatalytic mechanisms of the BiVO4@PANI photocatalyst were proposed. The enhanced antibacterial and photocatalytic activity could be attributed to the high surface area and combined impact of PANI and BiVO4, which promoted the migration efficiency of photo-generated electron holes. These findings open up ways for the potential use of BiVO4@PANI in industries, environmental remediation, pharmaceutical and medical sectors. Nevertheless, biocompatibility for human tissues should be thoroughly examined to lead to future improvements in photocatalytic performance and increase antibacterial efficacy.

A Review on Thiazole Based Colorimetric and Fluorimetric Chemosensors for the Detection of Heavy Metal Ions.

Thiazole and its derivatives play an important role in biological and non-biological fields due to several structural and electronic behaviors associated with it. Thiazole derivatives act as chemosensors because they formed metal complexes upon interacting with various heavy metal ions like Cd2+, Co2+, Cr3+, Fe3+, Ag+, Al3+, Cu2+, Pd2+, Hg2+, Ni2+, Ga3+, In3+, Sn4+, Pb2+, Zn2+ as well as other cations. These metal ions are of prime importance from the environmental point of view with high. This review article focuses on the thiazole-based colorimetric as well as fluorometric sensor for the recognition of different heavy metal cations in various specimens like agricultural, biological, and environmental. It also summarizes the binding stoichiometry, detection limit, pH, structure, and practical application of the reported thiazole-based chemosensors. Further, the sensing performances, have been discussed and compared with some reported organic sensors.

Nanotextured CeO2-SnO2 Composite: Efficient Photocatalytic, Antibacterial, and Energy Storage Fibers.

Bacterial infections remain a serious and pervasive threat to human health. Bacterial antibiotic resistance, in particular, lowers treatment efficacy and increases mortality. The development of nanomaterials has made it possible to address issues in the biomedical, energy storage, and environmental fields. This paper reports the successful synthesis of CeO2-SnO2 composite nanofibers via an electrospinning method using polyacrylonitrile polymer. Scanning and transmission electron microscopy assessments showed that the average diameter of CeO2-SnO2 nanofibers was 170 nm. The result of photocatalytic degradation for methylene blue dye displayed enhanced efficiency of the CeO2-SnO2 composite. The addition of SnO2 to CeO2 resulted in the enhancement of the light absorption property and enriched charge transmission of photoinduced electron-hole duos, which conspicuously contributed to momentous photoactivity augmentation. Composite nanofibers exhibited higher specific capacitance which may be accredited to the synergism between CeO2 and SnO2 particles in nanofibers. Furthermore, antibacterial activity was screened against Escherichia coli and CeO2-SnO2 composite nanofibers depicted excellent activity. The findings of this work point to new possibilities as an electrode material in energy storage systems and as a visible-light-active photocatalyst for the purification of chemical and biological contaminants, which would substantially benefit environmental remediation processes.

A sustainable approach to the degradation of dyes by fungal species isolated from industrial wastewaters: Performance, parametric optimization, kinetics and degradation mechanism.

Fungal abetted processes are among the finest approaches for the transformation or degradation and decolorization of dyes in effluents. In this piece of research; biodegradation and metabolic pathways of two toxic dyes Congo Red (CR) and Reactive black 5 (RB5) by two strains of Aspergillus sp. fungus in batch experiments has been investigated. Morphological characteristics of the isolates were observed with both light and electron microscopies. Based on molecular characterization the isolates were identified as Aspergillus flavus and Aspergillus niger. The degradation was also optimized via. operational parameters such as pH, temperature, incubation time, inoculums size, dye concentration, carbon sources and nitrogen sources. Degradation measurements revealed that the isolates effectively degraded 90% and 96% of CR and RB5 respectively. Metabolites were identified with Liquid chromatography-mass spectrometry (LCMS) and degradation pathways of the dyes were proposed. Toxicity assay Phaseolus mungo seeds showed that pure CR and RB5 dyes exhibits significant toxicity whereas fungal treated dye solution resulted in an abatement of the toxicity and cell viability was increased. The results stipulated in this article clearly showed the effectiveness of the isolates on detoxification of CR and RB5 dyes.

Label-Free Myoglobin Biosensor Based on Pure and Copper-Doped Titanium Dioxide Nanomaterials.

In this study, using pure and copper-doped titanium dioxide (Cu-TiO2) nanostructures as the base matrix, enzyme-less label free myoglobin detection to identify acute myocardial infarction was performed and presented. The Cu-TiO2 nanomaterials were prepared using facile sol-gel method. In order to comprehend the morphologies, compositions, structural, optical, and electrochemical characteristics, the pure and Cu-TiO2 nanomaterials were investigated by several techniques which clearly revealed good crystallinity and high purity. To fabricate the enzyme-less label free biosensor, thick films of synthesized nanomaterials were applied to the surface of a pre-fabricated gold screen-printed electrode (Au-SPE), which serves as a working electrode to construct the myoglobin (Mb) biosensors. The interference study of the fabricated biosensor was also carried out with human serum albumin (HSA) and cytochrome c (cyt-c). Interestingly, the Cu-doped TiO2 nanomaterial-based Mb biosensor displayed a higher sensitivity of 61.51 µAcm-2/nM and a lower detection limit of 14 pM with a response time of less than 10 ms.

Highly Sensitive and Selective Eco-Toxic 4-Nitrophenol Chemical Sensor Based on Ag-Doped ZnO Nanoflowers Decorated with Nanosheets.

Herein, we have developed a novel sensing electrode to detect the eco-toxic 4-nitrophenol (4-NP). Ag-doped-ZnO nanoflowers were synthesized by facile hydrothermal method and examined by several characterization techniques in order to understand the morphology, crystal structure, composition, and surface properties. Morphological results were confirmed by the formation of Ag-doped ZnO nanoflowers decorated with nanosheets. Ag-doped ZnO/glassy carbon electrode (GCE) electrode-material-matrix was used for electrochemical sensing of toxic 4-NP. Under optimized conditions, Ag-doped ZnO/GCE modified electrode exhibits high-sensitivity and selectivity compared to the bare GCE electrode. The Ag-doped ZnO/GCE modified electrode exhibits high electrocatalytic oxidation towards 4-NP. Anodic peak current of 4-NP is increased linearly by increasing the concentration of nitrophenol. Additionally, Ag-doped ZnO/GCE shows a wide range of sensitivity from 10 µM to 500 µM, and a linear calibration plot with a good detection limit of 3 µM (S/N = 3). The proposed Ag-doped ZnO/GCE modified electrode showed high sensing stability. In addition, the oxidation mechanism was studied. The obtained results revealed that the Ag-ZnO/GCE electrode could be the promising sensing electrode for 4-NP sensing.