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.
Research in nanotechnology involves the development of new materials at the nanometric scale, especially in the case of nanoparticles, where the use of metals and semiconductors has been the object of intense research. In this work, we have reported the synthesis of novel nanomaterials based on bimetallic particles of rare earths, which opens a new field of application for lanthanides in nanophotonics, nanoelectronics, and nanomedicine. We report the synthesis of Eu-Au nanoparticles by bioreduction methods and the corresponding structural characterization by using high-resolution electron microscopy. Eu-Au nanoparticles were synthesized at different pH values, and all the nanoparticles were studied for their characteristics. Among the nanoparticles obtained at different pH values, pH ) 8 was found to be optimal for obtaining the smallest clusters on the basis of the size distribution and other characteristics. The structures of these bimetallic clusters are comparable to the main metal clusters, which were reported earlier.LA0340495
The development of a highly reusable, non-toxic catalyst for the effective removal of 4-nitrophenol (4-NP) from marine water is a key challenge due to its diverse effects on living organisms. Herein, in situ green fabricated pyridinic N anchored Ag2O/Au decorated porous silica (CG-Ag2O/Au-SiO2) using spent coffee grounds (CG) powder is introduced as a reusable catalyst to mitigate 4-NP, Methylene blue (MB), Rhodamine 6G (R6G) and their mixture in the spiked deionized, river and marine water samples. Exceptionally high structural activity and excellent reusability of catalysts up to 15 cycles have been demonstrated due to the accessibility of a large number of active sites from pyridinic N-anchored Ag2O and Au particle surfaces. CG-Ag2O/Au-SiO2 with the lower Ag and Au contents of 0.59 and 0.11 wt% (ICP-MS) of active catalytic sites exhibit a superior activity parameter of 6000 s−1 g−1 (4-NP), 6357 s−1 g−1 (MB), and 2892 s−1 g−1 (R6G) than chemically synthesized and reported, bare and hybrid structures. Furthermore, the CG-Ag2O/Au-SiO2 shows excellent stability in marine water with promising reusability performance (≈93% after 15 successive cycles). Density functional theory (DFT) studies reveal that the observed high catalytic efficiency originates from the pyridinic N presence on the Ag2O/Au structures.
As biodiesel (BD)/Fatty Acid Alkyl Esters (FAAE) is derived from vegetable oils and animal fats, it is a cost-effective alternative fuel that could complement diesel. The BD is processed from different catalytic routes of esterification and transesterification through homogeneous (alkaline and acid), heterogeneous and enzymatic catalysis. However, heterogeneous catalysts and biocatalysts play an essential role towards a sustainable alternative to homogeneous catalysts applied in biodiesel production. The main drawback is the supporting material. To overcome this, currently, Metal-Organic Frameworks (MOFs) have gained significant interest as supports for catalysts due to their extremely high surface area and numerous binding sites. This review focuses on the advantages of using various MOFs structures as supports for heterogeneous catalysts and biocatalysts for the eco-friendly biodiesel production process. The characteristics of these materials and their fabrication synthesis are briefly discussed. Moreover, we address in a general way basic items ranging from biodiesel synthesis to applied catalysts, giving great importance to the enzymatic part, mainly to the catalytic mechanism in esterification/transesterification reactions. We provide a summary with recommendations based on the limiting factors.
The dry washing method is an alternative to replace water washing, thereby reducing the negative impacts of contamination. However, commercial adsorbents come from industrial processes that, due to their composition, may not be such a sustainable resource in the global biodiesel production process. In this study, the use of organic residues, such as sawdust, coconut fiber, nutshell, rice husk and water hyacinth fiber, were proposed as bioadsorbents for the purification of biodiesel from waste cooking oil (WCO). Quality parameters such as the acid value, water content, and free and total glycerin content were evaluated and compared with those of commercial resins such as Magnesol® and Amberlite™. Promising results were obtained using sawdust during the purification process, achieving a 31.6% reduction in the acid value compared to that of unpurified biodiesel, the reduction was 31.3% more efficient than Amberlite™. Sawdust adsorbed free glycerin at 55.8%, being more efficient than Amberlite™. The total glycerin values were similar between commercial resins and sawdust. A water content values were similar than Amberlite™ and better than that with Magnesol®, at 4.3% and 39.81%, respectively. These results show that sawdust can be used as an alternative bioadsorbent in a dry purification method for biodiesel being a residue with less environmental impact.
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