الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Waste substances varying from domestic to industrial residues cause detrimental toxins on the surrounding environment and human health. The volume of waste and recyclables generated from the residences during the COVID Virus outbreak has increased and is a major issue in all scientific agendas. Many wastes are rich in carboxylic acids, polyphenols, alkaloids, glycosides, flavonoids, etc. They can effectively be used for metal ion reduction. Green nanoparticles exhibited a plethora of promising candidates for different applications. As a result, waste can be used as a utility resource to create valuated products. Thre review of thesis explores recent trends in valorizing costless, large amount-based wastes for the green production of silver nanoparticles and their diverse applications. The promising roles of rich-active component biowaste for promoting AgNPs synthesis are discussed. The antimicrobial potency of different microbes was reviewed combined with biomedical applications, and the toxicity of Ag was explored. Besides, the review emphasizes how green synthesized AgNPs can be effectively used as a supercapacitor. The challenge and future vision should manage the solid waste, especially during the COVID outbreak, to exhibit safe applications of various nanoparticles for environmental, medical, and energy storage applications.
The first part of thesis summarized in : Plasmonic silver nanoparticle, AgNPs, (" ~ "14.1 nm) having an absorption peak at 421 nm was fabricated via a biogenic, rapid, and costless technique using Banana Waste Peduncles (BWP) as new disposals instead of plant extracts. Then, Degussa (P25) has been in-situ added in one-step to AgNPs using the microwave synthesis to produce solar-light activation. HR-TEM images showed incorporation of P25 over plasmonic AgNPs grown by spherical shape. Based on the photocatalytic process, methylene blue (MB) was fully degraded and 16 min was sufficient for chromium (IV) reduction. AgNPs/Degussa nanocomposite is photochemical stable even after eight cycles. Besides, the antimicrobial activity indicated the capability of the nanocomposite, as an efficient antimicrobial agent for killing and prevent the diffusion of the nominated microbes; S. aureus, E. coli, C. albicans and A. niger due to the synergistic effect of AgNPs. The cell viability showed up to 94.85% reliable cell migration, particularly at higher concentrations. The significant improvement of photoactivity and stability of the as-synthesized photocatalysts might be relevant for their reusability in practical applications.
While, the second part summarized : is well known that biogenic synthesis, as compared to other processes, has proven to be highly effective in the fabrication of silver nanoparticles (AgNPs). Thus, our current study focused on synthesizing AgNPs using coffee waste extract (CWE), which acted as a reductant and stabilizing agent. CWE contains many compounds identified by HPLC, which reduce, cap, and stabilize AgNPs in its solution. The as-synthesized AgNPs were produced with a monodispersed small size around 20 nm and formed in-plane dipole plasmon resonances of hexagonal nanoplates. characterizations affirm the creation of AgNPs by creating specific bands and peaks directly close to the hexagonal AgNPs. It was also proved that the as-prepared AgNPs (12 mg) could degrade the phenol compounds (20 mL) with removal percent (94.6%) in a short time in the presence of citric acid. Additionally, the second promising application of AgNPs was the tendency to remove the hazard 2, 4 dinitroaniline (2,4DNA) with a percent more than 97% while using only 7 mg of AgNPs. Moreover, the green synthesized AgNPs are superior in inhibiting bacterial growth and killing most infected microbes such as B. subtilis, P. aeruginosa, S. aureus, and E. coli. The electrochemical characteristics of the AgNPs were evaluated using a three-electrode system. The calculated specific capacitance was 280 F g-1 at 0.56 A g-1. Furthermore, after 1000 cycles at 2.2 A g-1, the AgNPs electrode demonstrates an excellent cycling stability behavior with 94.8 % capacitance retention. Based on the previous promising results, it can be concluded that CWE is an environmentally benign extract to prepare AgNPs with no cost and no time as well to be easily used for many a great domain in photocatalytic, phenol compound removals and production of functional nanodevices.