Methylene Blue Solution Research Articles

The production of bacterial cellulose from coconut water and its application as a green photocatalyst composite membrane

AbstractIn this research work, bacterial cellulose was produced from the fermentation of coconut water and incubated for 4, 5, and 6 days. The bacterial cellulose membrane was utilized as immobilized silver nanoparticles (AgNPs). A green photocatalyst membrane was prepared by reducing silver ions in the bacterial cellulose matrix structure using local fruit extracts, tomatoes, Citrus hystrix fruit, and mangosteen peel as a reducing agent. The composite was dried in the oven to obtain a more durable fixed structure. The properties of produced bacterial cellulose were determined by measuring the thickness, water retention capacity (WRC), cellulose content, and swelling. The functional group and crystallinity index of bacterial cellulose were observed by FTIR and XRD instrument analysis. The SEM EDX analysis confirms that the silver ions were successfully reduced in the BC matrix, and the UV–Vis spectrum showed that the composite membrane has the ability to degrade the methylene blue solution under sunlight irradiation. The maximum degradation efficiency of the composite membrane against 5 ppm methylene blue solution was achieved by the composite membrane reduced by tomatoes, with a value of 93%. This result proved that the composite membrane produced in this research has excellent capabilities as a green photocatalyst for degrading wastewater containing dye pollutants.

Preparation of poly(methyl methacrylate)-zinc oxide hybrid nanoparticles via miniemulsion polymerization

The encapsulation of zinc oxide (ZnO) nanoparticles with poly(methyl methacrylate) in the presence of triethylene glycol dimethacrylate (TEGDMA) as a crosslinking agent was synthesized by the miniemulsion polymerization technique. The ZnO as a catalyze was varied from 1 wt% - 7 wt%. Several techniques were used to analyze the PMMA/TEGDMA/ZnO hybrid. The morphology and particle size distribution of the PMMA hybrid was observed using a field emission scanning electron microscope (FE-SEM). The diameter of the PMMA/TEGDMA/ZnO hybrid was in the range of 57 nm to 115 nm. The morphology of the PMMA/ZnO hybrids was sphere-shaped with a narrow particle size distribution and no agglomeration of the hybrids occurred. The encapsulation and crystalline structure of the PMMA ZnO hybrid were determined using a high-resolution transmission electron microscope (HR-TEM). The HR-TEM image demonstrated that the ZnO was encapsulated in the PMMA hybrid. In addition, the high magnification of the TEM image demonstrated the lattice spacing of ZnO and the diffraction mode image presented the crystalline structure of ZnO. Therefore, the photocatalytic properties of the PMMA/ZnO hybrid were examined via the degradation of methylene blue (MB) solution under dark and UV-A irradiation. It was found that the photocatalytic activities of the PMMA/ZnO hybrid increased when the ZnO content increased up to 7 wt%. The maximum MB degradation for PMMA/TEGDMA/ZnO 7 wt% and PMMA/ZnO 7 wt% were 80.1 % and 77.6 %, respectively. Thus, the photocatalytic efficiency of the PMMA/ZnO increased in the presence of TEGDMA as a crosslinking agent.

Comparative Evaluation of Luting Efficacy Between a Dual-Cure and Light-Cure Resin Cement on Its Application on Root Surface Indirect Restorations: An In Vitro Study.

Aim The aim is to evaluate the degree of dye penetration between a dual-cure and conventional resin cement on its application on the root surface indirect restorations to provide a reference for clinical choice. Materials and methods Ten freshly extracted human maxillary central anteriors were selected and randomly divided into twogroups of five each. Teeth were prepared for veneer restoration, andveneers were luted using two groups of cementsCalibra veneer cement and Fusion Ultra D/C cement. Afterthey were immersed in methylene blue dye solution for 24 h, the specimens were then sectioned buccolingual into three halves in a parallel vertical planeand measured dye penetration using a stereomicroscope (Zeiss). The data collected was recorded by the dye penetration index (0-4) and statistically analyzed using the IBM SPSS Statistics for Windows, Version 24(Released 2016; IBM Corp., Armonk, New York, United States). Results It is evident that group 1 (Calibra veneer cement) showed the lowest mean score of 0.43 mmand group 2 (Fusion Ultra D/C) showed a highest mean score of 0.72 mm. Overall, when the two groups were compared for microleakage using SPSS, there was a significant difference among the groups. Conclusion It was determined that both the resin cements evaluated in this study showed microleakage to some level given the limits of the investigation and the findings. To evaluate the dye penetration of microleakage, the Calibra veneer resin cement showed a better marginal adaptability for veneer restoration.Further investigations withbroader methodology and more clinical simulation are needed to evaluate other resin cements available for root surface indirect restorations to be analyzed for prospective clinical outcomes.

Evaluation of kinetic constants uncertainty for the metrologically sound comparison of photodegradation efficiency using TiO2 catalysts

The comparison of the efficiency of a pair of catalysts for the photodegradation of a compound in the same irradiation conditions is affected by many independent and correlated random and systematic effects. These comparisons become objective and indisputable if the efficiency difference is estimated with uncertainty, producing an interval encompassing the “true” difference value with a known probability. This work presents a tool for the detailed evaluation of the uncertainty of estimated kinetic constant values and differences by the Monte Carlo Method simulation of all relevant uncertainty components. First-order kinetics were quantified from regression of the concentrations of studied compounds over various degradation times. The efficiency of methylene blue (MB) and sulfamethazine (SMZ) photodegradation using various solid-state catalysts was quantified and compared. Synthesised TiO2 nanoparticles are more efficient than the purchased TiO2 for MB degradation. For SMZ degradation, ruthenium-doped titanate nanowires and ruthenium-doped titanate nanotubes are equally efficient and more efficient than pristine titanate nanowires. The efficiency equivalence can be challenged by quantifying larger and/or less uncertain SMZ concentrations. First-order kinetics was tested by taking the simulated confidence limits of the intercept of the linear regression used to describe this kinetic order. Kinetic constants with asymmetric distribution and a relative expanded uncertainty for a 95 % confidence level between 3.6% and 17% were quantified. Three successively more uncertain procedures for preparing calibrators for the quantification of MB by UV/Vis spectroscopy were tested, concluding that since the same calibration curve is used to quantify all MB solutions, kinetic quantification is not proportionally or significantly affected by this uncertainty component.

Guiding role of esophageal variceal diameter in treatment of endoscopic ligation: an animal experimental study

In this study, according to the Location, Diameter, Risk factor (LDRf) classification principle, the influence and effect of esophageal varices diameter on the degree of complete ligation of multicyclic ligator were investigated. Methods. The esophageal veins of healthy piglets were filled with methylene blue solution, and the in vitro pig esophageal varices model was made, which were divided into three groups according to the diameter of esophageal varices: D1, 0.4–1.0 cm; D2, 1.1–1.5 cm; and D3, 1.6–2.0 cm. Finally, the ligation effect of each group was analyzed statistically. A total of 407 ligations were performed on the simulated esophageal variceal model. There were 103 ligations in the D1 group and 98 were complete (95.15%, 98/103); 151 ligations in the D2 group and 47 were complete (31.13%, 47/151); and 153 ligations in the D3 group but none were complete (0%, 0/153). There was significant difference in the degree of complete ligation between the two groups (χ2 = 38.0014, P ≤ 0.001). In the varicose ligation model, the complete ligation effect was the most complete and robust when the varicose diameter was 0.4–1.0 cm. This study showed that the varicose vein diameter in LDRf classification was reasonable and feasible to guide endoscopic varicose vein ligation.

Synthesize of heterostructure TiO2 by simultaneous doping of double silver and phosphate to degradation of methylene blue under visible light

Photocatalysts show great potential as compounds for restoring contaminated water and wastewater resources. The study aims to synthesize a composite with high photocatalytic potential under visible light to photodegrade the organic pollutants. Ag/Ag3PO4@ TiO2 were synthesized by doping Ag and Ag3PO4 on TiO2. The composite was characterized using X-ray diffraction analysis (XRD), diffuse reflectance spectroscopy, Field emission scanning electron microscopy, and Energy-dispersive X-ray spectroscopy analyses, and its photodegradation ability was investigated by methylene blue. Utilization of pure TiO2 yielded a removal efficiency that was merely half of the efficiency achieved when using modified particles, owing to the reduction of TiO2 s band gap from 3.2 to 1.94 eV. In addition to its enhanced photocatalytic performance under visible light, the synthesized Ag/Ag3PO4@TiO2 photocatalyst demonstrated remarkable efficiency in removing dyes such as methylene blue from aqueous solutions. The removal efficiency at pH less than 7 in 50 ppm methylene blue solution using 3 g/l photocatalyst over 45 min visible light irradiation was approximately 90 percent. Under sunlight, photocatalytic reactions exhibited an efficiency of over 95 percent within 45 min. It can be concluded that the simultaneous introduction of metallic (Ag) and nonmetallic (PO43−) dopants significantly increases the efficiency of electron–hole recombination suppression in the photocatalyst and also decreases the band gap.

Study of the photocatalytic activity of clay supported TiO2 nanoparticles for methylene blue degradation.

The photocatalytic degradation of a methylene blue (MB) solution was studied using a formulation of TiO2 nanoparticles (NPs) suspended in a commercial antibacterial paint, and supported on clay strips. All experiments were carried out in a batch reactor containing a UV-C light source and the MB solution under stirring. Parameters such as catalyst mass loading, MB concentration, as well as catalyst properties were considered for the experimental procedure. The effect of the mass loading on the photocatalytic activity of the TiO2 formulations immobilized on the clay supports was evaluated using 100, 200, and 500 mg of TiO2 on 40 mL of paint, sampling the MB solution under degradation at 0, 2, 5, 10, 20, 50, 100 and 200 min. The aliquots were analyzed by optical spectroscopy in the 400-1000 range to determine the absorbance, calculate the concentration with the Beer-Lambert equation, and obtain the amount of MB degradation. The maximum photocatalytic degradation of MB for the supported photocatalyst was 52%, 55%, and 60%, respectively. For comparison, suspended TiO2 nanoparticles lead to ca. 95% of MB photodegradation in ca. 60 min. The supported photocatalysts were tested in three consecutive cycles of 200 min to study the mechanical and photocatalytic stability. The activity of the photocatalysts with mass loading of 100 and 200 mg TiO2 decreased to ca. 35% after the three cycles, while the formulation with 500 mg TiO2 remained stable for three cycles. The final samples of each cycle were characterized by XRF, discarding erosion of the material from the support.

Comparison of coronal sealing of flowable composite, resin-modified glass ionomer, and mineral trioxide aggregate in endodontically treated teeth: An in-vitro study

Background: Coronal seal is one of the essential factors that affects the success of endodontic treatment and reinforces the apical seal. The intra-orifice barrier is an efficient alternative approach to decrease coronal leakage in endodontically treated teeth and various materials have been used for this purpose. This study aimed to compare the coronal sealing of flowable composite, resin-modified glass ionomer (RMGI), and mineral trioxide aggregate (MTA) in endodontically treated teeth. Materials and Methods: In this in vitro study, 35 single-canal canine teeth were divided into five groups, including flowable composite, RMGI, MTA, positive control, and negative control groups. The teeth were filled with restorative materials according to the factory's instructions. Afterward, the samples were immersed in 2% methylene blue dye solution for 1 week at 37°C and 100% humidity condition. Finally, the teeth were sectioned longitudinally and dye penetration was measured using a stereomicroscope with ×10. Data were analyzed with Kolmogorov–Smirnov and Kruskal–Wallis tests (α = 0.05). Results: The positive control group showed the highest amount of dye penetration compared to other groups (12.34 ± 0.46). Dye penetration in the MTA group was significantly lower (4.25 ± 0.31) compared to the RMGI group (5.94 ± 0.24) (P = 0.02). Moreover, while the dye penetration in the MTA group was lower than in the flowable composite group (5.65 ± 0.26), the difference was not statistically significant (P = 0.12). Conclusion: MTA reduces the coronal leakage and provides an acceptable coronal seal in endodontically treated teeth, especially compared to RMGI, and therefore, using MTA as an intra-orifice barrier increases the endodontic treatment success rate.

Photocatalytic degradation of methylene blue by efficient TiO2‐partially reduced graphene oxide composites

The effect of graphene oxide with different reduction degrees on the photocatalytic efficiency of titanium dioxide‐graphene (TiO2‐G) composites has not been systematically studied. In this paper, titanium dioxide‐partially reduced graphene oxide (TiO2‐PRGO) nanocomposites were prepared by a modified one‐step solvent‐thermal method and further reduced with ascorbic acid to obtain TiO2‐PRGO(xh) with a higher degree of reduction (ascorbic acid 80° reduced TiO2‐PRGO x h, x = 1, 2, 3, 4). The composites were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT‐IR), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), and ultraviolet–visible diffuse reflectance spectroscopy (DRS). The transient photocurrent response and electrochemical impedance results show that TiO2‐PRGO has the most outstanding photoelectrochemical properties. Compared with pure TiO2 and other samples, the TiO2‐PRGO nanocomposites exhibited excellent photocatalytic properties, and their photocatalytic efficiencies for the degradation of methylene blue (MB) were up to seven times higher than those of the pure TiO2 nanomaterials, and twice that of TiO2‐PRGO(4h). The photodegradation of methylene blue by the composites decreased as the degree of PRGO reduction increased. The efficient photocatalytic performance of TiO2‐PRGO can be attributed to the high TiO2 loading and good electrical conductivity. Notably, TiO2‐PRGO photocatalysis for 90 min resulted in 100% degradation of MB. Meanwhile, TiO2‐PRGO has good reusability, and the degradation rate of TiO2‐PRGO remained at 95% after four times of degradation in MB solution.

Degradation of Methylene Blue by Sol-Gel One-Step Method with B-W Co-doped TiO2

In this work, B-W co-doped TiO2 photocatalysts were synthesized by a sol-gel method using ammonium metatungstate and boric acid as W and B sources, respectively. The effects of W/Ti and B/Ti ratios on the photocatalytic activities were investigated. When W/Ti = 3.5/100 and B/Ti = 5/100, the degradation rate of a 40 mg/L methylene blue solution reached 82.45% within 120 min and the quasi-first-order kinetic constants were 12.39 times and 1.89 times of the quasi-first-order kinetic constants of pure TiO2 and 3.5%W-TiO2, respectively. The characterization results showed that the modified TiO2 crystal type obtained by W and B co-doping was anatase, and the gel was calcined to produce substituted W doping and interstitial B doping (Ti-O-B-Ti). W and B doping can form impurity energy levels below the conduction band and above the valence band, respectively; under their synergistic effect, the bandgap of 5%B-3.5%W-TiO2 was reduced to 2.65 eV, which lowered the the compounding efficiency of the hole-electron pairs and improved the photocatalytic performance.

Evaluation of Sealing Ability of New Composite Filling Material

This study was conducted to investigate the sealing ability (microleakage) of new composite restorative materials at tooth/composite interface.Thirty non carious, extracted human premolars teeth were mounted in acrylic resin, the teeth were randomly divided into three groups (n=10) according to the type of composite (tetric T-Econom, Evo ceram,IPS Empress). A standardize class V (5×3×2) mm dimensions cavity was prepared on the facial surface of each tooth (each group with corresponding bur type). After the specimens were filled with three types of composite restoration. They stored for one month in 37ºc distilled water, thermo cycled for 500 cycles between (5ºc & 55ºc) and immersed in 2% methylene blue solution for 24h., and then sectioned longitudinally. For both occlusal and gingival margins, dye penetration at the tooth/composite interfaces were scored from 0-3 under stereomicroscope at a magnification x10. Data were analyzed using unpaired T-test, ANOVA, and Duncan’s multiple rang test at 5% significant level.Kruskal-wallis test show that there was a significant difference in microleakage between the three types of composite it represent that there was less microleakage in group filled with IPS Empress while tetric T-Econom show the highest leakage.There was no significant difference in microleakage between IPS Empress and Evo ceram composite filling.AS Conclusions; Within the limitations of this in vitro study the results show that there was less microleakage in the cavities filled with IPS Empress composite and EVO ceram composite as compared with Tetric T-Econom composite.

Enhanced Photocatalysis of Electrically Polarized Titania Nanosheets.

Titania (TiO2) nanosheets are crystals with controlled, highly ordered structures that improve the functionality of conventional TiO2 nanoparticles. Various surface modification methods have been studied to enhance the effectiveness of these materials as photocatalysts. Surface modifications using electrical polarization have attracted considerable attention in recent years because they can improve the function of titania without changing its composition. However, the combination of facet engineering and electrical polarization has not been shown to improve the functionality of TiO2 nanosheets. In the present study, the dye-degradation performance of polarized TiO2 nanosheets was evaluated. TiO2 nanosheets with a F/Ti ratio of 0.3 were synthesized via a hydrothermal method. The crystal morphology and structure were evaluated using transmission electron microscopy and X-ray diffraction. Then, electrical polarization was performed under a DC electric field of 300 V at 300 °C. The polarized material was evaluated using thermally stimulated current measurements. A dye-degradation assay was performed using a methylene blue solution under ultraviolet irradiation. The polarized TiO2 nanosheets exhibited a dense surface charge and accelerated decolorization. These results indicate that electrical polarization can be used to enhance the photocatalytic activity of TiO2.

Laser-Driven Rapid Synthesis of Metal-Organic Frameworks and Investigation of UV-NIR Optical Absorption, Luminescence, Photocatalytic Degradation, and Gas and Ion Adsorption Properties.

In this study, we designed a platform based on a laser-driven approach for fast, efficient, and controllable MOF synthesis. The laser irradiation method was performed for the first time to synthesize Zn-based MOFs in record production time (approximately one hour) compared to all known MOF production methods with comparable morphology. In addition to well-known structural properties, we revealed that the obtained ZnMOFs have a novel optical response, including photoluminescence behavior in the visible range with nanosecond relaxation time, which is also supported by first-principles calculations. Additionally, photocatalytic degradation of methylene blue with ZnMOF was achieved, degrading the 10 ppm methylene blue (MB) solution 83% during 1 min of irradiation time. The application of laser technology can inspire the development of a novel and competent platform for a fast MOF fabrication process and extend the possible applications of MOFs to miniaturized optoelectronic and photonic devices.

Synergetic Adsorption of Dyes in Water by Three-Dimensional Graphene and Manganese Dioxide (PU@RGO@MnO2) Structures for Efficient Wastewater Purification

The improper discharge of industrial wastewater causes severe environmental pollution and the textile industry’s dye usage contributes significantly to industrial wastewater pollution. Hence, an effective method for removing the harmful substance methylene blue (MB) from dye wastewater is proposed. This method adopts a three-dimensional graphene composite material based on manganese dioxide (MnO2), named polyurethane@ reduced graphene oxide@ MnO2 (PU@RGO@MnO2). First, graphene is prepared with hydrazine hydrate as a reducing agent and polyurethane as a framework. MnO2 nanoparticles are synthesized by the reaction of potassium permanganate (KMnO4) with carbon. These nanoparticles are then loaded onto the three-dimensional framework to create the composite material. Finally, adsorption and removal experiments for MB are conducted to compare the performance of the composite material. The results indicate that the graphene based on the polyurethane framework exhibits favorable mechanical properties. The unique three-dimensional lattice structure provides abundant active sites for loading MnO2 nanoparticles, significantly increasing the contact area between the adsorbent and MB solution and thus improving the adsorbent utilization rate (reaching 94%). The nanoparticles synthesized through the reaction of KMnO4 with carbon effectively suppress the agglomeration phenomenon. Additionally, the introduction of dynamic adsorption and dynamic removal modes, aided by a water pump, substantially enhances the adsorption and removal rates, showcasing excellent performance. The research on a multi-porous three-dimensional structure holds significant practical value in water treatment, offering a new research direction for dye wastewater treatment.

Fabrication of conductive ceramic composite for electrothermal-assisted photocatalytic degradation of frozen organic pollutants and indoor climate control

Photocatalytic applications for frozen organic pollutants are limited by their poor de-icing performance. Herein, we develop a conductive ceramic (CC) composite with excellent electrothermal and photocatalytic performance for degradation of frozen organic pollutants. The introduction of carbonized graphite and multi-walled carbon nanotube (MWCNT) endows the composite with excellent electrothermal performance, which can quickly raise to 400 °C within 300 s at a voltage of 12 V. Furthermore, ZnO nanoparticles (NPs) endows the composite with outstanding photocatalytic performance. The catalytic ability of the composite increased as increasing the applied voltages. The obtained composite could reach a high degradation rate (95.8%) for methylene blue (MB) after 120 min under a 12 V power supply. The obtained composite exhibited an excellent photocatalytic performance for frozen MB solution, which could melt the solution quickly and then degrade the organic pollutant. The heat generated by the composite can effectively melt the frozen MB solution and promote its photocatalytic performance, thus considerably broadening the photocatalytic applications in cold region or in winter.

Preparation and characterization of cellulose-based activated carbon by cesium chloride chemical method

Carbon adsorbent material with a specific surface area as high as 436 m2/g was prepared by chemical activation method using cellulose as raw material and cesium chloride as activator, and its structure was characterized. Its adsorption performance on methylene blue solution was investigated, and the adsorption thermodynamics of crystalline violet dye at different temperatures was studied. The results showed that the surface of the prepared activated carbon material was smooth with abundant pores. The methylene blue adsorption value was as high as 176 mg/g, and it could adsorb methylene blue solution quickly and efficiently. It had good adsorption effect on crystal violet solution, the saturated adsorption amount reaches 281 mg/g at 40 °C, and the removal reached 92%, which indicated a self-heating adsorption reaction. Thus, CsCl could be used as an activator of wood raw material for the preparation of activated carbon samples.

Preparation and characterization of polyvinyl chloride based carbon materials with high specific surface area

Using PVC as raw material and KOH as activator, the carbon adsorption material with ultra-high specific surface area up to 5677.2 m2/g was prepared by chemical activation method, and its structure was characterized to study its adsorption performance on methylene blue solution; the activated mixture was analyzed for chlorine element and the recovery of chlorine element was calculated. The results show that the surface of the obtained activated carbon material is in the shape of smooth lotus root flakes with well-developed pore structure; the adsorption value of methylene blue adsorption can reach 765.0 mg/g, which can adsorb methylene blue solution quickly and efficiently; the elemental chlorine can be recovered efficiently with a recovery rate of 95.33 %, which can effectively reduce the toxic hydrogen chloride gas produced in the process of PVC pyrolysis. Excellent adsorption capacity of H2, CO2 and CH4. This experiment can provide an effective method for the harmless treatment of PVC.

Facile construction of robust superhydrophobic ZIF‐8@pulp/cellulose nanofiber (CNF) membrane for multifunctional applications

Given the increasing contamination of freshwater supplies, it is essential to effectively treat industrial wastewater. However, treating industrial wastewater using a single method is challenging due to the presence of complex contaminants like petroleum, organic dyes, bacteria, and other complex contaminants. In this study, we present a straightforward and scalable approach to prepare multifunctional nanocellulose-based membranes (NM) that exhibit superhydrophobicity, self-cleaning, oil/water separation, photocatalysis, and anti-bioadhesion properties. To begin with, we created NM by extruding fiber slurry onto a stencil and drying it. Next, we built a polyurethane (PU)/ZIF‐8/1H, 1H, 2H, 2H‐perfluorooctyltriethoxysilane (POTS)-based superhydrophobic layer by spraying it over the NM's surface. By employing the aforementioned processes, we successfully integrated multiple functions into a single superhydrophobic NM. Our results demonstrate that the NM-PU/ZIF-8/POTS membrane exhibits superior hydrophobicity performance, with a high-water contact angle (166.8 ± 0.8°) and a low rolling angle (5 ± 0.3°). Moreover, these samples retain high-water contact angles and low rolling angles even in harsh environments such as acid and alkali solutions, high temperatures, abrasion resistance, UV aging resistance, bending and folding, tape peeling, and self-cleaning. The NM-PU/ZIF-8/POTS membrane also exhibits high and stable oil-water separation performance, with a separation efficiency of 94.6% and a relatively high separation flux (133.2 L·m−2·h−1). At the same time, the NM-PU/ZIF-8/POTS membrane exhibits water-in-oil emulsion separation ability. The membrane’s stability, effectiveness, and reusability were demonstrated through ten repetitions of degradation experiments using aqueous methylene blue solution, with the NM-PU/ZIF-8/POTS membrane exhibiting an excellent degradation rate (>94%). Finally, the bioadhesion resistance test indicated a reduction of 69.1% in the adhesion rate of the NM-PU/ZIF-8/POTS membrane. Overall, the creation of the NM-PU/ZIF-8/POTS membrane serves as a useful inspiration for the practical application of superhydrophobic NM in multifunctional integration, while also broadening the scope of membrane applications.

Correlations between the anti-corrosion properties and the photocatalytic behavior of epoxy coatings incorporating modified graphene oxide deposited on a zinc substrate.

This research aimed to create a substrate-coating system based on zinc and an epoxy resin incorporating modified graphene oxide, which possesses two key characteristics: effective resistance against corrosion and the ability to harness photocatalytic properties. Furthermore, correlations between the anti-corrosion properties and the photocatalytic behaviour of the coatings were made. Thin epoxy (EP) layers embedding 0.1 wt% graphene oxide (GO), reduced graphene oxide (rGO), and modified graphene oxide with (3-aminopropyl)-triethoxysilane (APTES) or poly(amidoamine) (PAMAM) dendrimer were applied on a zinc (Zn) substrate using the dip-coating method. Anti-corrosion properties of coated Zn samples were investigated through electrochemical impedance spectroscopy (EIS) measurements. They showed that the corrosion protection effect is more prominent for EP containing functionalized GO, the highest in the case of GO-PAMAM. The results of the EIS measurements indicated also that the corrosion protection provided by EP-rGO is smaller than that of EP. The photocatalytic properties of the coatings were studied by exposure of the samples to Methylene Blue (MB) solution followed by monitoring the model dye degradation through UV-Vis measurements. To determine the changes in the anti-corrosion properties due to photocatalysis, the coated Zn samples were put through additional EIS measurements. The same coatings applied to a glass substrate lacked photocatalytic properties, indicating that the Zn substrate is accountable for the degradation of MB. Furthermore, the incorporation of GO or functionalized GO into the coating amplifies this effect. From EIS spectra, it was determined that the protective properties loss observed after 3 days is due to coating delamination during exposure to MB solution, the EP-GO-APTES retaining the best adhesion of the coating, 98% remaining on Zn after a cross-hatch test. The corrosion measurements were complemented by examining the morphology and structure of the coatings and the modified GO particles. All things considered, the Zn/EP-GO-APTES system shows the best ability to break down organic pollutants, keeping a good anti-corrosive property and adhesion.

High-efficiency and conveniently recyclable g-C3N4/diatomite/calcium alginate composite gel bead photocatalysts

Graphitic carbon nitride (g-C3N4) is considered an encouraging photocatalyst with visible light activity. However, the utilization of g-C3N4 nanosheets in powdered form in wastewater treatment presents difficulties in the recovery and recycling of photocatalysts. Consequently, supported g-C3N4 photocatalysts have been developed for practical applications. In the present work, a novel, conveniently recyclable composite gel bead photocatalyst, comprised of g-C3N4/diatomite/calcium alginate, has been fabricated using a dropwise addition strategy. The systematic investigation of photocatalytic activity and photochemical stability of the composite gel beads was conducted through the degradation of methylene blue (MB) under visible light exposure (λ > 420 nm). As a result, g-C3N4/diatomite/calcium alginate gel beads show a high photocatalytic effectiveness of 95% when MB solution is disintegrated at 120 minutes.