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Until now, many efficient catalysts have been reported that are used for the reduction of nitroarenes. However, a catalyst reusability is a challenge that is often faced in practical environment. In this report, we designed a hydrogel composite (CMC-LDH), which act as support and making it possible to address this challenge. In this research work, zinc/aluminum based layered double hydroxides (Zn/Al LDH) have been assembled with carboxymethyl cellulose (CMC) to prepare CMC/LDH hydrogel beads. The CMC/LDH hydrogel beads were prepared by the ionotropic gelation method. For CMC/LDH/Au preparation, the already prepared CMC/LDH beads were kept in gold ion (Au3+) solution, and their subsequent reduction with sodium borohydride (NaBH4). For the characterization of the prepared samples different instrumental techniques, such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy, and scanning electron microscopy (SEM) were adopted. For the catalytic evaluation of CMC/LDH/Au, it was utilized as a catalyst in 4-NP and 4-NA reduction reactions. The continuity of the reaction was monitored by a UV-visible spectrophotometer. Rate constant (kapp) of 0.48474 min-1 and 0.7486 min-1 were obtained for 4-NP and 4-NA reduction, respectively. The hydrogel beads were recycled and reused for up to five successive cycles without significantly changing their catalytic efficiency.
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Carboximetilcelulosa de Sodio , Nanopartículas del Metal , Compuestos de Zinc , Carboximetilcelulosa de Sodio/química , Oro , Nanopartículas del Metal/química , Hidrogeles/química , Zinc , Compuestos Orgánicos , Hidróxidos/químicaRESUMEN
Hydrogen production, catalytic organic synthesis, carbon dioxide reduction, environmental purification, and other major fields have all adopted photocatalytic technologies due to their eco-friendliness, ease of use, and reliance on sunlight as the driving force. Photocatalyst is the key component of photocatalytic technology. Thus, it is of utmost importance to produce highly efficient, stable, visible-light-responsive photocatalysts. CIS stands out among other visible-light-response photocatalysts for its advantageous combination of easy synthesis, non-toxicity, high stability, and suitable band structure. In this study, we took a brief glance at the synthesis techniques for CIS after providing a quick introduction to the fundamental semiconductor features, including the crystal and band structures of CIS. Then, we discussed the ways doping, heterojunction creation, p-n heterojunction, type-II heterojunction, and Z-scheme may be used to modify CIS's performance. Subsequently, the applications of CIS towards pollutant degradation, CO2 reduction, water splitting, and other toxic pollutants remediation are reviewed in detail. Finally, several remaining problems with CIS-based photocatalysts are highlighted, along with future potential for constructing more superior photocatalysts.
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Contaminantes Ambientales , Restauración y Remediación Ambiental , Catálisis , Luz , TecnologíaRESUMEN
In this work, CQDs decorated MnIn2S4/CdS/Bi2S3 heterojunction was prepared successfully by hydrothermal technique for photocatalytic disinfection of Escherichia coli (E. coli) and mineralization of methyl orange (MO) dye. The charge transferal route and mineralization process in CQDs-MnIn2S4/CdS/Bi2S3 heterojunction were comprehensively investigated by advanced spectroscopic techniques. The improved visible-light activity and enhanced photo-generated charge transferal efficacy caused dual Z-scheme CQDs-MnIn2S4/CdS/Bi2S3 heterojunction to achieve boosted photodegradation ability. The catalytic degradation trend was followed as CQDs-MnIn2S4/CdS/Bi2S3 > MnIn2S4 > CdS > Bi2S3. The dye was mineralized within 180 min under visible light irradiation. The effect of reaction parameters, pH effect, catalyst dosage, and H2O2 addition on MO degradation was also investigated. The degradation rate was maximal at pH 4 with a pseudo-first-order rate constant, 0.0438 min-1. The assessment of antibacterial properties revealed that CQDs-MnIn2S4/CdS/Bi2S3 composite effectively inactivated E. coli under visible light. Scavenging experiments, transient photocurrent response, and electron spin resonance spectroscopy suggested that â¢[Formula: see text] and holes were the dominant reactive species. The Z-scheme heterojunction is recyclable up to ten photocatalytic cycles according to recycling experiments. This research indicates the importance of dual Z-scheme CQDs decorated MnIn2S4/CdS/Bi2S3 heterojunction in wastewater remediation.
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Carbono , Puntos Cuánticos , Puntos Cuánticos/química , Escherichia coli , Peróxido de Hidrógeno , Antibacterianos/química , LuzRESUMEN
The potential of nanocomposite membranes (NCMs) prepared by the sodium alginate polymer and embedded with synthesized zeolitic imidazole framework-8 (ZIF-8) as fillers having microporous structure in the application of separation of gaseous mixture generated by the process of methane reforming was assessed. ZIF-8 crystals were created through hydrothermal synthesis, with sizes varying from 50 to 70 nm. NCMs were prepared with a 15% filler loading, i.e., synthesized ZIF-8. NCMs (ZIF-8) having H2 permeability of 28 Barrer and H2/CH4 selectivity of 125 outperformed neat polymer membranes in terms of separation performance at ambient temperature and 4 kg/cm2 pressure. The purity of H2 increased to as high as 95% among the measured values. The NCMs did not, however, outperform a neat polymer membrane in terms of their ability to separate mixtures of gases. Moreover, the combination of ZIF-8 as a filler with sodium alginate was new and had not been reported previously. As a result, it is worthwhile to investigate.
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The development of a sensitive glucose monitoring system is highly important to protect human lives as high blood-glucose level-related diseases continue to rise globally. In this study, a glucose sensor based on polyaniline-bimetallic oxide (PANI-MnBaO2) was reported. PANI-MnBaO2 was electrochemically synthesized on the glassy carbon electrode (GCE) surface. The as-prepared PANI-MnBaO2 was characterized by field emission scanning electron microscopy, Fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. Glucose sensing on PANI-MnBaO2 is based on the electrocatalytic oxidation of glucose to the glucolactone, which gives oxidation current. The oxidation potential for glucose was 0.83 V, with a limit of detection of 0.06 µM in the linear and in the concentration range of 0.05 µM-1.6 mM. The generated current densities displayed excellent stability in terms of repeatability and reproducibility with fast response. The development of a sensitive glucose sensor as obtained in the current study would ensure human health safety and protection through timely and accurate glucose detection and monitoring.
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WBE has been a monitoring system that can give purposeful and inclusive real-time assessments of civic society as well as environmental health. This concept review introduces WBE as a surveillance scheme and initial warning outbreaks of contagious diseases caused by harmful SARS-CoV-2 with pandemic potential. Examining biomarkers of contagious diseases as evidence in polluted water taken from wastewater treatment plants suggests that these systems can be examined to get epidemiological data for checking the transmission of infectious B.1.1.529 to different areas. Thereafter, various benefits of surveillance are provided to analyse health information and pinpoint different problems that may be occurring in the workstation. Surveillance is followed by intervention steps that improved the work environment and prevent further progression of the disease. This information will help to improve early detection strategies, designing a prevention strategy to reduce their spread, infection control and therapies, thus, strengthening our global preparedness to fight future epidemics. In the end, a comprehensive discussion on the remaining challenges and opportunities for epidemiology has been given for future research perspectives.
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COVID-19 , Enfermedades Transmisibles , COVID-19/epidemiología , Monitoreo del Ambiente , Humanos , Pandemias , SARS-CoV-2 , Aguas ResidualesRESUMEN
The mass immunization is the prioritised post-pandemic phase offering preventive countermeasure for COVID-19 pandemic. However, it is crucial to tackle the environmental impact of COVID-19 vaccine waste for sustainable vaccination management because a prolonged immunisation campaign is expected. As the pace of vaccine production, distribution and mass vaccination has been expedited, there is a simultaneous rise in plastic derived vaccine waste including syringes, needles, used/unused vaccine vials, vaccine packaging, and protective gear (surgical facemasks, gloves, face shields, etc). Henceforth, in view of the repercussions of heaping plastic waste in the environment, this article provides a perspective on the usage of synthetic and natural materials as potential substituents for vaccination tools. The biodegradable polymeric gums such as cellulose, gellan, pectin, etc. have been successfully applied for the fabrication of surgical facemasks. The highly suggestive practice is replacement of conventional polypropylene based plastics with bioplastics or paper for vaccine packaging. The usage of biodegradable bio-plastics as packaging material along with environmentally friendly face masks can help to achieve the zero waste approach. The discussion in the article significantly highlights the necessity of opting sustainable solutions of disinfecting and substituting vaccination tools for an environment friendly ongoing vaccination campaign.
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Styrene-butadiene rubber (SBR) is a synthetic polymer primarily used in the tire industry, due to its good collaborative properties with additives and fillers. In the present work, we aim to synthesize an SBR composite reinforced with graphene oxide filler to be made biodegradable. In composite preparation, we fabricated styrene-butadiene rubber/graphene oxide/collagen (SBR/GO/COL) composites by adding a biodegradable biomolecule of elastin collagen fillers at 1.5 wt% and 2.5 wt%. Those prepared SBR/GO/COL composites, along with pure SBR and SBR/GO as control samples, were characterized using advanced analysis techniques, and their biodegradability was also evaluated. From microscopy examination results, the morphology of pure SBR had been improved after the addition of GO for SBR/GO composite by revealing a compact structure with a smoother surface. As for the SBR/GO/1.5COL sample, the 1.5 wt% COL filler was found to be effectively embedded in the SBR/GO matrix. However, the 2.5 wt% COL amount led to the formation of an aggregated structure in the SBR/GO/2.5COL sample due to the unreacted interface between COL filler and SBR/GO. The porosity had also been improved for SBR/GO/1.5COL sample, imparting it with a surface area suitable for tires in the automobile industry. From elemental analysis, the presence of nitrogen was detected for the collagen-filled SBR composite, proving the successful incorporation of collagen fibrils. The physicochemical analysis also detected a trace of graphene oxide and collagen functional groups in the SBR composite. In addition, the thermal analysis revealed those collagen-filled composites had stable heat tolerance behavior, which is suitably used in extreme weather conditions. Moreover, the SBR/GO/1.5COL sample exhibited good characteristics in both mechanical and biodegradable properties. Thus, the product of SBR/GO/1.5COL could be regarded as a promising composite for green tires in the auto industry in the future.
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Styrene butadiene rubber (SBR), is a synthetic polymer and the most abundantly used in the tire industry, which have good collaborative properties with additives and fillers. In present work, we aim to synthesize SBR composite having the properties of graphene oxide filler and made it to be biodegradable. In composite preparation, we fabricated styrene-butadiene rubber/graphene oxide/lignin composites by adding biodegradable biomolecule of lignin fillers at varying 1-3 wt% quantities amount. Those prepared SBR composites were characterized using advanced analysis techniques, and also their biodegradability was. From microscopy examination results, the morphology of pure SBR composite had been improved after the addition of graphene oxide, while the 1 wt% lignin filled SBR sample revealed well-integrated morphology with crest-and-trough-like feature, showcasing the lignin fibrils could strengthen the molecular interaction between graphene oxide nano sheet and SBR rubber. For 2 wt% lignin filled SBR sample, it exhibited large protuberants due to the aggregation effect of lignin fibrils. However, bulky and bundle structure of protuberant was more significantly formed in 3 wt% lignin filled SBR, as a result of poor interface between lignin and SBR rubber. The porosity had also been improved for 1 wt% lignin filled SBR sample, imparting it with great surface area to act as tire in automobile application. The physico-chemical analysis also detected the trace of graphene oxide and lignin functional groups in the SBR composite. In addition, the thermal analysis revealed those lignin-filled composites had stable heat tolerance behavior, which suitably used in extreme weather condition. Moreover, the 1 wt% lignin filled SBR sample exhibited good characteristics in both mechanical and biodegradable properties. Thus, the composite of 1 wt% lignin filled SBR could be regarded as a promising candidate for green tire application in the future.
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Lignina , Goma , Automóviles , Butadienos , Elastómeros , Grafito , Lignina/química , Óxidos/química , Goma/química , Estireno , EstirenosRESUMEN
The appearance of the contagious virus COVID-19, several revelations and environmental health experts punctually predicted the possibly disastrous public health complications of coexisting catching and airborne contamination-arbitrated disease. But much attention has been given on the outdoor-mediated interactions. Almost 3.8 million premature deaths occur every year globally due to the illness from indoor air pollution. Considering the human staying longer span indoors due to restricted human activities or work from home, the indoor air quality (IAQ) might show prominent role for individual health life. Currently, the Environmental Protection Agency (EPA) ensures no regulation of indoor airborne pollution. Herein, the paper underlines the common bases of indoor air pollution, poor IAQ, and impacts of the aerosolized airborne particles on the human health. In order to address these challenges and collective contagion events in indoor environment, several emerging control techniques and preventive sustainable solutions are suggested. By this, more innovations need to be investigated in future to measure the impact of indoor air pollution on individual health.
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Abstract: More than 1 million illnesses and 70,000 deaths were reported due to novel COVID-19 by the end of the first quarter of 2020. In April 2020, the World Health Organization declared COVID-19 a pandemic. The striking resemblance between COVID-19 and its forerunners SARS and MERS, as well as earlier findings on the impact of meteorological conditions on the spread of SARS and MERS, prompted researchers to investigate the relationship between meteorological conditions and the spread of COVID-19. In this work, we statistically studied the effect of different meteorological parameters such as average temperature, humidity, dew point, and wind speed on the spread of COVID-19 pandemic in Egypt and its latitude (Algeria, Egypt, Iran, Saudi Arabia, Turkey). Our findings revealed that there is a correlation between several meteorological parameters and the spread of COVID-19, but that, contrary to popular belief, the virus does not disappear when the temperature rises. Our theory is that either the virus became active in Egypt and its latitude as the temperature rose, or the humidity became unstable when the temperature rose during the summer season. A log-linear quasi-Poisson regression model was used to estimate the relationship between the studied metrological parameters and the spread of COVID-19. The findings of the study will have ramifications for future control and prevention efforts in Egypt and its latitude.
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Green hematite nanoparticles were synthesized using pomegranate peel extract of different concentrations (2 g, 4 g, and 6 g) and in the presence of the peel residuals. The obtained products defined as PP/GNH (I), PP/GNH (II), and PP/GNH (III) referring to the hematite nanoparticles at different concentrations compositing with pomegranate peel residuals. The products were addressed as green adsorbents for methylene blue dye contaminants in water. They exhibit superior adsorption properties with theoretical qmax of 666, 1111, and 909 mg/g for PP/GNH (I), PP/GNH (II), and PP/GNH (III), respectively. The equilibration times were attained after 480 min for the three products. The isotherm and kinetic studies indicate that the adsorption systems for the synthetic materials are of chemisorption type. The adsorption behaviors of these systems can be demonstrated according to Pseudo-second order as well as Elovich kinetic model. Furthermore, the adsorption results reflected a mono-layer uptake form which was more suitable for the Langmuir model than other investigated models. The products also showed high performances when it comes to remove the dyes investigated such as methylene blue Congo red, safranin, methyl orange, and crystal violet. Finally, green fabricated nano hematite/pomegranate peel composites are of high stability and can be reused for five cycles.Communicated by Ramaswamy H. Sarma.
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Granada (Fruta) , Contaminantes Químicos del Agua , Azul de Metileno/química , Cinética , Compuestos Férricos , Colorantes/química , Adsorción , Contaminantes Químicos del Agua/química , Concentración de Iones de HidrógenoRESUMEN
To overcome the key challenges associated with cement dust, such as inhalable size, toxic ions, and the existence of large quantities of useless materials, researchers investigated an innovative and unusual conversion of toxic cement dust into Mayenite nanoparticles. Mayenite is a natural structure that can be used as a filler in a variety of industrial applications. The formation of Mayenite nanoparticles was achieved through a thermal reaction at 1000°C for 2 h between cement dust and aluminum oxide. Different techniques were used to characterize the synthesized Mayenite nanoparticles, revealing the formation of the target phase as well as the reduction of toxic ions present in cement dust. According to Scherrer's equation, the crystallite size of bypass and synthesized Mayenite nanoparticles is 45 and 30 nm, respectively. Also, with the aid of TEM analysis, the particle size distribution of the produced Mayenite nanoparticles was found to be 27±7 nm. The toxic ions, especially chlorides and sulphates, were reduced by 86% and 50%, respectively, according to X-ray fluorescence results. These findings are important for the future use of Mayenite, 12CaO.7Al2O3 (C12A7), nanoparticles formed from toxic cement dust recycling.
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Compuestos de Aluminio/química , Óxido de Aluminio/síntesis química , Compuestos de Calcio/química , Polvo , Minerales/síntesis química , Óxido de Aluminio/química , Cloruros , Calor , Minerales/química , Nanopartículas , Tamaño de la Partícula , Reciclaje , SulfatosRESUMEN
Oxygen vacancy as a typical point defect has incited substantial interest in photocatalysis due to its profound impact on optical absorption response and facile isolation of photocarriers. The presence of oxygen vacancy can introduce the midgap defect states, which promote extended absorption in the visible region. The redistribution of electron density at the surface can stimulate the adsorption and activation kinetics of adsorbates, manifesting optimal photocatalytic performance. Despite such alluring outcomes, the ambiguity in understanding the precise location, appropriate concentration, and oxygen vacancy role is still a long-standing task. The present review article comprehensively outlines the identification of oxygen vacancy defects at bulk or on the surface and its ultimate effect on the photocatalytic degradation of phenolic compounds. Particular emphasis has been drawn to summarize the critical influence of oxygen vacancy on different factors such as crystal structure, bandgap energy, electronic structure, and charge carrier mobility by integrating experimental results and theoretical calculations. We have also explored the reaction pathways and the intermediate chemistry of phenol photodegradation by analyzing the molecular activation (O2, H2O, and sulphate activation) through oxygen vacancy defects. Finally, the review concludes with the various challenges and future perspectives, aiming to provide a firm base for further progressions towards photocatalysis.
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Nanoestructuras , Oxígeno , Fenoles , FotólisisRESUMEN
Conocarpus fiber is a lignocellulosic biomass rich in cellulose potentially used for producing nanocrystalline cellulose (NCC), a biomaterial extensively employed in various application fields. In the present work, different hydrolysis times of 10, 20 and 30 min were applied to chemically pre-treated Conocarpus fiber to produce CPNC1, CPNC2, and CPNC3 particles. With acid hydrolysis treatment, the yield of NCC product was successfully retained at 17-19%. Individual, rod-like shapes of NCC particles could be clearly observed under microscopy examination. From chemical composition analysis, a relatively pure cellulose compartment was produced for all NCC samples with substantial removal of lignin and hemicellulose. The physicochemical analysis proved that each nanoparticle sample possessed strong cellulose crystalline structure. For thermal analyses, the heat resistance of NCCs was gradually enhanced with the increased hydrolysis times. Therefore, the extracted NCC product from Conocarpus fiber could be a green nano-filler for developing nanocomposite material in the future.
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In this work, we report the facile, environmentally friendly, room-temperature (RT) synthesis of porous CuO nanosheets and their application as a photocatalyst to degrade an organic pollutant/food dye using NaBH4 as the reducing agent in an aqueous medium. Ultrahigh-resolution field effect scanning electron microscopy images of CuO displayed a broken nanosheet-like (a length of â¼160 nm, a width of â¼65 nm) morphology, and the lattice strain was estimated to be â¼1.24 × 10-3 using the Williamson-Hall analysis of X-ray diffraction plots. Owing to the strong quantum size confinement effect, CuO nanosheets resulted in an optical energy band gap of â¼1.92 eV, measured using Tauc plots of the ultraviolet-visible (UV-vis) spectrum, resulting in excellent photocatalytic efficiency. The RT synthesized CuO catalyst showed a high Brunauer-Emmet-Teller surface area of 30.88 ± 0.2313 m2/g (a correlation coefficient of 0.99972) with an average Barrett-Joyner-Halenda pore size of â¼20.385 nm. The obtained porous CuO nanosheets exhibited a high crystallinity of 73.5% with a crystallite size of â¼12 nm and was applied as an efficient photocatalyst for degradation of the organic pollutant/food dye, Allura Red AC (AR) dye, as monitored by UV-vis spectrophotometric analysis and evidenced by a color change from red to colorless. From UV-vis spectra, CuO nanosheets exhibited an efficient and ultrafast photocatalytic degradation efficiency of â¼96.99% for the AR dye in an aqueous medium within 6 min at RT. According to the Langmuir-Hinshelwood model, photodegradation reaction kinetics followed a pseudo-first-order reaction with a rate constant of k = 0.524 min-1 and a half-life (t 1/2) of 2.5 min for AR dye degradation in the aqueous medium. The CuO nanosheets showed an outstanding recycling ability for AR degradation and would be highly favorable and an efficient catalyst due to the synergistic effect of high adsorption capability and photodegradation of the food dye.
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Photocatalytic materials for photocatalysis is recently proposed as a promising strategy to address environmental remediation. Metal-free graphitic carbon nitride (g-C3N4), is an emerging photocatalyst in sulfate radical based advanced oxidation processes. The solar-driven electronic excitations in g-C3N4 are capable of peroxo (OâO) bond dissociation in peroxymonosulfate/peroxydisulfate (PMS/PDS) and oxidants to generate reactive free radicals, namely SO4â¢- and OH⢠in addition to O2â¢- radical. The synergistic mechanism of g-C3N4 mediated PMS/PDS photocatalytic activation, could ensure the generation of OH⢠radicals to overcome the low reductive potential of g-C3N4 and fastens the degradation reaction rate. This article reviews recent work on heterojunction formation (type-II heterojunction and direct Z-scheme) to achieve the bandgap for extended visible light absorption and improved charge carrier separation for efficient photocatalytic efficiency. Focus is placed on the fundamental mechanistic routes followed for PMS/PDS photocatalytic activation over g-C3N4-based photocatalysts. A particular emphasis is given to the factors influencing the PMS/PDS photocatalytic activation mechanism and the contribution of SO4â¢- and OH⢠radicals that are not thoroughly investigated and require further studies. Concluding perspectives on the challenges and opportunities to design highly efficient persulfate-activated g-C3N4 based photocatalysts toward environmental remediation are also intensively highlighted.
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The authors wish to make the following corrections to this paper [...].
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Mesoporous silica (MCM-48) was synthesized and used as a catalyst for supporting the nickel oxide photocatalyst. The loading of nickel oxide on MCM-48 results in a considerable reduction in the bandgap energy to 2.4 eV. MCM-48 was used as a catalyst and back-supporter for the nickel oxide to enhance its photocatalytic properties along with adsorption capacity. Therefore, the adsorption capacity of MCM-48/Ni2O3 was enhanced by 17.5% and 32.2% compared to Ni2O3 and MCM-48, respectively. Furthermore, the percentage of photocatalytic degradation was improved by approximately 68.2% relative to the free-standing Ni2O3. The MCM-48/Ni2O3 proved the chemisorption adsorption mechanism that happens in multilayer form through the heterogeneous surface. This through fixing such Ni2O3 particles over the nanoporous topography to provide more exposed hot adsorption and photocatalytic sites for the incident light photons. Therefore, supporting Ni2O3 catalytic particles onto MCM-48 produces a new category of photocatalytic systems with promising active centers for the efficient degradation of Congo red dye molecules.
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Rojo Congo , Níquel , Adsorción , CatálisisRESUMEN
A novel nanocomposite of cellulose based on multiwalled carbon nanotube (MWCNT) was synthesized by a simple solution mixing-evaporation method. The morphology, thermal investigations, electrocatalytic oxidation of amitriptyline were analyzed at multi-walled carbon/cellulose nanocomposite in detail. The amitriptyline (AMT) drug was electrochemically studied in a phosphate buffer at different pH using the MWCNT/cellulose modified glassy carbon electrode (GCE). As per the linear relationship among AMT along with peak current, differential pulse voltammetry technique has been established for their quantitative pharmaceutical's determination. The oxidation potential shifted negatively compared to GCE, showing that the MWCNT/cellulose modified electrode had an excellent catalytic activity for the AMT oxidation. The anodic peak current varied linear response with AMT's concentration in the range of 0.5 to 20.0 µM with a LOD of 0.0845 µM and LOQ of 0.282 µM, respectively. The proposed method was effectively put on the determination of AMT in pharmaceutical and urine samples. This novel methodology is presented here as an example of a complete development methodology for the determination of amitriptyline drug and sensor for use in healthcare fields.