Green Synthesis of Ag-Au Bimetallic Nanocomposites Using Waste Tea Leaves Extract for Degradation Congo Red and 4-Nitrophenol
17 Mar 2021-Sustainability (Multidisciplinary Digital Publishing Institute)-Vol. 13, Iss: 6, pp 3318
TL;DR: In this article, the authors report eco-friendly and facile technology to synthesize Ag-Au bimetallic nanocomposites, which can efficiently degrade Congo red and 4-nitrophenol in water and in the presence of sodium borohydride.
Abstract: A sustainable supply of pure water is a great challenge in most developing and third-world countries. Nanomaterial-based technology offers technological development for wastewater purification. Nanocatalysis hydrogenation of nitroarene and dye molecules is a hot model in many research fields. Herein, we report eco-friendly and facile technology to synthesize Ag-Au bimetallic nanocomposites. The synthesized nanocomposites are characterized by ultraviolet–visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy and high-resolution transmission electron microscopy. The synthesized nanocomposite can efficiently degrade Congo red and 4-nitrophenol in water and in the presence of sodium borohydride. The results show that it degrades Congo red and 4-nitrophenol entirely within 6 and 7 min, respectively. These results could be useful for the green synthesis of Ag-Au bimetallic nanocomposites and help to remove organic dye molecules and nitroaromatics from wastewater.
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TL;DR: In this paper , the basic perceptions of the green synthesis of metal nanoparticles and their supported-catalyst-based reduction of 4-nitrophenol (4-NP) to 4-aminophenol(4-AP) are discussed.
Abstract: Noble metal (silver (Ag), gold (Au), platinum (Pt), and palladium (Pd)) nanoparticles have gained increasing attention due to their importance in several research fields such as environmental and medical research. This review focuses on the basic perceptions of the green synthesis of metal nanoparticles and their supported-catalyst-based reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The mechanisms for the formation of these nanoparticles and the catalytic reduction of 4-NP are discussed. Furthermore, the parameters that need to be considered in the catalytic efficiency calculations and perspectives for future studies are also discussed.
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TL;DR: In this paper , a simple, green, and efficient approach is described to produce novel bentonite/Ag nanocomposite wherein the preparation of Ag nanoparticles (Ag NPs) deployed the laser ablation method in air; Ag NPs are deposited on the bentonite via the magnetic stirring method.
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TL;DR: In this paper , a versatile process for the fabrication of a microporous heterogeneous palladium nanocatalyst on a novel spherical, biodegradable, and chemically/physically resistant catalyst support consisting of chitosan (CS) and cigarette waste-derived activated carbon (CAC).
Abstract: This study reports a versatile process for the fabrication of a microporous heterogeneous palladium nanocatalyst on a novel spherical, biodegradable, and chemically/physically resistant catalyst support consisting of chitosan (CS) and cigarette waste-derived activated carbon (CAC). The physicochemical properties of the microporous Pd-CS-CAC nanocatalyst developed were successfully determined by FTIR, XRD, FE-SEM, TEM, BET, and EDS techniques. TEM studies showed that the average particle size of the synthesized Pd NPs was about 30 nm. The catalytic prowess of microporous Pd-CS-CAC was evaluated in the reduction/decolorization of various nitroarenes (2-nitroaniline (2-NA), 4-nitroaniline (4-NA), 4-nitrophenol (4-NP), and 4-nitro-o-phenylenediamine (4-NPD)) and organic dyes (methyl red (MR), methyl orange (MO), methylene blue (MB), congo red (CR), and rhodamine B (RhB)) in an aqueous medium in the presence of NaBH4 as the reducing agent at room temperature. The catalytic activities were studied by UV-Vis absorption spectroscopy of the supernatant at regular time intervals. The short reaction times, mild reaction conditions, high efficiency (100% conversion), easy separation, and excellent chemical stability of the catalyst due to its heterogeneity and reusability are the advantages of this method. The results of the tests showed that reduction/decolorization reactions were successfully carried out within 10-140 s due to the good catalytic ability of Pd-CS-CAC. Moreover, Pd-CS-CAC was reused for 5 consecutive times with no loss of the initial shape, size, and morphology, confirming that it was a sustainable and robust nanocatalyst.
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TL;DR: In this article, an integrated approach for utilization of microalga Scenedesmus sp. for fabrication of catalytic and antimicrobial silver nanoparticle composite was demonstrated, where the algal biomass was harvested from an open raceway pond of 30,000 L scale used for CO2 sequestration.
Abstract: In this study, we have demonstrated an integrated approach for utilization of microalga Scenedesmus sp. for fabrication of catalytic and antimicrobial silver nanoparticle composite. The algal biomass was harvested from an open raceway pond of 30,000 L scale used for CO2 sequestration. The dried biomass served as a green, nontoxic, reducing and immobilizing agent for synthesis of silver nanoparticles, producing biomass-silver nanoparticle composite. ICP-OES was used to monitor the uptake of silver ions by biomass and subsequent formation of nanoparticles. The composite was calcined at 400 °C to fix the nanoparticles and prevent fouling. The calcined biomass-silver nanoparticle (CB-AgNP) composite was characterized using FESEM-EDAX, XRD and TGA. The CB-AgNP composite was used for the first time, as a heterogenous catalyst for reduction of a prominent industrial pollutant, p-nitrophenol. The reduction was carried out in the presence of NaBH4 in aqueous medium under ambient conditions. Batch experiments were conducted to evaluate the effect of calcination temperature, load of material and its reusability, on the catalytic efficiency of material. It was found that as low as 5 mg mL−1 CB-AgNP material reduced more than 80% and 95% of p-nitrophenol within 1 min and 15 min of exposure, respectively. Rate of PNP reduction was 0.60 mg L−1 min−1. The composite was easily recovered and reused for continuous batches of p-nitrophenol reduction. The efficiency of catalysis decreased with ten cycles of reuse; however, with an intermittent overnight water wash, the material regained its catalytic activity. Furthermore, the CB-AgNP composite also possessed excellent antimicrobial activity against pathogenic microbes. Two strains each of gram + ve and gram − ve bacteria and three strains of pathogenic fungi were used in the antimicrobial studies using well diffusion method and it was found to be active against all the microbes. The CB-AgNP composite is a potential candidate for a reusable heterogenous catalyst for designing continuous flow system for remediation of industrial effluents rich in p-nitrophenol. Its efficacy against common pathogenic bacteria and fungi can be harnessed for simultaneous antimicrobial treatment of the water. Moreover, this antimicrobial property will further inhibit the biofouling and eventual clogging of the material used in a packed column when used for water treatment.
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TL;DR: This review provides an overview of the synthesis of both man-made and biogenic nitroaromatic compounds, the bacteria that have been identified to grow on and completely mineralize nitrobiotic compounds, and the pathways that are present in these strains.
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654 citations
TL;DR: In this paper, the basic concepts and recent developments and advances of gold nanoparticle (AuNP)-catalyzed 4-nitrophenol (4-NP) reduction to 4-aminophenol by sodium borohydride, including the catalytic mechanism, the variety of stabilizers, and dendritic, natural and heterogeneous AuNP supports are presented.
632 citations
TL;DR: The results suggest that the reduction of metal ions and stabilization of the resultant particles in the first two solutions involved the same class of biomolecules, including flavonoids, which were present in comparable amounts in both the tea leaf broth and ethyl acetate extract, but are absent in the CH(2)Cl( 2) extract of tea leaves.
494 citations