Search

Abstract Supercapacitors and water splitting cells have recently played a key role in offering green energy through converting renewable sources into electricity. Perovskite-type electrocatalysts such as BaTiO3, have been well-known for their ability to efficiently split water and serve as supercapacitors due to their high electrocatalytic activity. In this study, BaTiO3, Al-doped BaTiO3, Ce-doped BaTiO3, and Al-Ce co-doped BaTiO3 nanofibers were fabricated via a two-step hydrothermal method, which were then characterized and compared for their electrocatalytic performance. Based on the obtained results, Al-Ce co-doped BaTiO3 electrode exhibited a high capacitance of 224.18 Fg−1 at a scan rate of 10 mVs−1, high durability during over the 1000 CV cycles and 2000 charge–discharge cycles, proving effective energy storage properties. Additionally, the onset potentials for OER and HER processes were 11 and − 174 mV vs. RHE, respectively, demonstrating the high activity of the Al-Ce co-doped BaTiO3 electrode. Moreover, in overall water splitting, the amount of the overpotential was 0.820 mV at 10 mAcm−2, which confirmed the excellent efficiency of the electrode. Hence, the remarkable electrocatalytic performance of the Al-Ce co-doped BaTiO3 electrode make it a promising candidate for renewable energy technologies owing to its high conductivity and fast charge transfer.

Background and Objectives: Among different water treatment methods, photocatalytic process is applied as a new efficient technology with appropriate potential to remove inorganic, organic and microbial contaminants from water. This study aimed to evaluate photocatalytic removal of Escherichia coli and Streptococcus faecalis bacteria as microbial indicators of drinking water using immobilized ZnO nanoparticles on glass plates. Methods: In this study, at first characteristics of ZnO nanoparticles were determined using scanning electron microscope (SEM) equipped with EDX system and X-ray diffraction (XRD), then ZnO nanoparticles were immobilized on glass plates using thermal method. The water samples containing the studied bacteria were irradiated by different intensities of UV-A and the effects of intensity and duration of irradiation, number of bacteria, number of immobilized ZnO nanoparticles layers, and reactor flow on the photocatalytic removal of the bacteria were evaluated.Results: The optimal photocatalytic removal for both Escherichia coli and Streptococcus faecalis bacteria using one layer of immobilized ZnO nanoparticles, under 360 µWs/cm2 UV-A radiation for 2-40 and 2-50 minutes was 10-1000 CFU/100 ml. Photocatalytic process efficiency was promoted by increasing the duration and intensity of radiation intensity up to 360µWs/cm2 and was decreased by increasing the numbers of bacteria. In addition, Streptococcus faecalis bacteria were more resistant to photocatalytic process than Escherichia coli.Conclusion: photocatalytic removal of bacterial contaminations using immobilized ZnO nanoparticles on glass plates is a novel technology and effective process that could be considered for water disinfection.

Organic dyes constitute an integral part of industrial effluents. Advanced oxidation processes are efficient methods for the degradation of organic pollutants, one of the most promising of which is sonocatalysis. In this study, we aimed to immobilize MoS2 nanopetals on honeycomb-like biochar through a one-step hydrothermal method and evaluate its sonocatalytic performance in the degradation of acid blue 7 (AB7). The MoS2-Biochar composite demonstrated enhanced sonocatalytic activity, approved by its larger specific surface area (5.0 m2/g) and narrower bandgap (1.25 eV) compared with those of pure MoS2. Application of 1.5 g/L MoS2-Biochar (10:1) led to a 95 % decolorization of AB7 (20 mg/L) within 40 min of reaction time. Moreover, considerable degradation efficiencies were achieved for various organic pollutants, including hydroxychloroquine (96 %), levofloxacin (81 %), phenazopyridine (80 %), and tilmicosin (67 %) with initial concentration of 20 mg/L within 120 min of treatment. The synergy factor and degradation turnover value of the sonocatalytic process for decolorization of AB7 were calculated to be 4.88 and 27.37 µmol/h.gcat, respectively. Trapping experiments were conducted to determine the roles of various reactive species in the sonocatalytic degradation process, and holes were found to be the dominant species. Furthermore, the generated intermediates were identified using gas chromatography–mass spectrometry (GC–MS) analysis, which suggested a possible mechanism for the degradation process. A stable structure and acceptable reusability with a 16 % reduction in the decolorization efficiency after four consecutive sonocatalytic runs were observed for the 10:1 composite, suggesting a promising perspective for the application of the studied system in the efficient treatment of organic pollutants.

In this work, removal of dissolved oxygen in water through reduction by glucose, which was catalyzed by glucose oxidase – catalase enzyme, was studied. Central composite design (CCD) technique was applied to achieve optimum conditions for dissolved oxygen scavenging. Linear, square and interactions between effective parameters were obtained to develop a second order polynomial equation. The adequacy of the obtained model was evaluated by the residual plots, probability-value, coefficient of determination, and Fisher’s variance ratio test. Optimum conditions for activity of two enzymes in water deoxygenation were obtained as follows: pH=5.6, T=40°C, initial substrate concentration [S] = 65.5 mmol/L and glucose oxidase activity [E] = 252 U/Lat excess amount of catalase. The deoxygenation process during 30 seconds, in the optimal conditions, was predicted 98.2%. Practical deoxygenation in the predicted conditions was achieved to be 95.20% which was close to the model prediction.

Abstract Layered double hydroxides (LDHs), regarding their physical and structural properties, have different and wide applications industry and their increasing use may raise ecological and human health concerns. However, the potential toxicity mechanisms of LDHs in different organisms are still unclear. In the present work, after synthesizing of ZnFe-SO4 LDH and studying of its characterization by XRD, FT-IR, SEM, EDX-mapping, TEM and Raman, its toxicity in Tetradesmus obliquus was evaluated. According to experimental results, the growth of the algae and content of photosynthetic pigments were significantly decreased after treatment with 100 mg/L of ZnFe-SO4 LDH. The high dose exposure to the LDH also inhibited the activity of SOD and POD enzymes, possibly due to the LDH- catalyzed reactive oxygen species production. In addition, lipid peroxidation and the content of phenolic compounds, as no-enzymatic antioxidants were increased by enhancement of the LDH concentration. The rise of phenol, flavonoids and MDA contents could be regarded as some manifestations and responses to the toxic effects of the contaminant in the algae cells. The results provided a better understanding of the undesirable effects and toxicity of LDHs in aquatic organisms.

The health of all living organisms is greatly influenced by the quality of the water. Therefore, developing cost-effective, eco-friendly, and easily accessible methods is desperately needed to meet the high global demand for clean water. Recently, nanozyme-based dye degradation methods have been promising for the remediation of water pollution. In this work, peroxidase-mimic Co3O4/TiO2 nanocomposite was synthesized and characterized for its size, morphology, and crystalline structure. Colorimetric assay results showed that the peroxidase-like activity of the Co3O4/TiO2 nanocomposite was considerably enhanced compared to the pure Co3O4 NPs and TiO2 NPs. Besides excellent enzyme-mimic activity, the higher sonophotocatalytic dye degradation capability of the nanocomposite after immobilization on zeolite (Co3O4/TiO2@Ze) was also demonstrated. Under optimal conditions (pH = 5.0, 25 °C), 0.1 g/L of catalyst was able to degrade 100 % of methylene blue (MB) with 600 μM in the presence of 30 μM H2O2 within 12 min. GC/MS analysis and toxicity studies revealed less toxic metabolite production after treatment of MB with sonophotocatalytic Co3O4/TiO2@Ze. Modeling of MB degradation using artificial neural networks (ANN) with a 5:6:1 topology was successfully performed, and the results confirmed the fitness of theoretical and experimental outputs according to the calculated correlation coefficient values. The prepared nanocomposite could thus be used as a promising and highly effective catalyst for the removal of organic dyes from polluted water.

Summary: Lignin is an abundant polyaromatic polymer with a wide range of potential future uses. However, the conversion of lignin into valuable products comes at a cost, and medium- to high-value applications are thus appropriate. Two examples of these are polymers (e.g., as fibers, plasticizers, or additives) and flow batteries (e.g., as redox species). Both of these areas would benefit from lignin-derived molecules with potentially low molecular weight and high (electro)chemical functionality. A promising route to obtain these molecules is oxidative lignin depolymerization, as it enables the formation of targeted compounds with multiple functionalities. An application with high potential in the production of plastics is the synthesis of new sustainable polymers. Employing organic molecules, such as quinones and heterocycles, would constitute an important step toward the sustainability of aqueous flow batteries, and lignin and its derivatives are emerging as redox species, mainly due to their low cost and renewability.

Abstract Montmorillonite (MMt) is extensively applied as an efficient drug-carrier in designing drug delivery systems (DDS) due to its high specific surface area to load drugs. Modification of MMt via iron (Fe) blending can thus be a desirable method to improve its biocompatibility. Herein, magnetic nano-carriers involving the magnetic MMt (mMMt) core surrounded by chitosan (Chito) as a biopolymer and hyaluronic acid (HA) were prepared. To coat the mMMt fabricated through the coprecipitation of the Fe3+/Fe2+ ions in the presence of MMt, the acquired mMMt as the core was then treated with the Chito/HA solution to induce the cross-linked Chito/HA as the shell (namely, the Chito/HA-mMMt). The transmission electron microscopy (TEM) results accordingly revealed the existence of the mMMt inside the Chito/HA solution. Curcumin (CUR) and ciprofloxacin (CIP) were further employed as two model drugs. The CUR and CIP release from the Chito/HA-mMMt subsequently occurred in a sustained manner and pH-dependently. Additionally, an upsurge in the CUR and CIP release by applying an external magnetic field was observed. Thus, the prepared Chito/HA-mMMt hydrogels promise an outstanding potential performance in terms of expanding novel pH-dependent DDS with a sustained release behavior. The scratch assay of the given hydrogels also confirms their applications for wound healing.