Synthesis of Nanoparticles Using Different Biogenic Wastes

Nanoscience is a rapidly emerging scientific discipline that has generated significant attention among global scientists over the last several decades due to its multidisciplinary character and wide range of applications. The phrase ‘Nano’ is derived from a Greek word meaning dwarf, referring to materials or systems with minimal size ranges. Nanoscience explores the various unique features of the materials formed at the nanometer scale, whereas nanotechnology involves the creation, characterization, and use of nanoscale materials. Because of their enormous surface area and distinctive electronic properties, diverse nanostructures are useful for various applications, including optoelectronics, electronics, automobiles, and biomedical applications. These properties of the nanoscale materials largely depend on synthetic techniques. Two procedures, top-down and bottom-up techniques are generally utilized for the synthesis of nanoscale materials. Top-down procedures entail reducing the size of bulk materials to nanoscale utilizing various processes such as laser pyrolysis, electronic irradiation, mechanical exfoliation, evaporation/condensation, and so on. Bottom-up approaches involve the synthesis of nanomaterials from atomic-scale precursors via different reactions including hydrolysis, thermolysis, sol-gel method, hydrothermal method, and so on. In all circumstances, a suitable capping agent is required to avoid the aggregation of nanostructures and control the shape of the structures. These synthesis processes frequently yield undesirable by-products and pollutants, which cause environmental pollution and other biological dangers, limiting their use in a variety of clinical and biomedical settings. As a result, ecologically benign and biologically safe synthesis processes are very desirable. Green synthesis of various nanostructures is critical in addressing these concerns. Green synthesis of nanomaterials encourages creative synthetic procedures that minimize or eliminate the usage or creation of dangerous toxic substances throughout the synthetic operation. Green synthesis of metallic and nonmetallic nanoparticles with nontoxic biomolecules derived from natural resources such as plants, algae, fungi, yeast, and microorganisms is favorable in this regard. Different alkaloids, steroids, and tannins derived from plant barks, seeds, leaves, roots, and other parts can be employed as reducing and stabilizing agents for bioreduction in the manufacture of various metal and metal oxide nanoparticles. However, there are various commercially valued plants, and the utilization of these plant products for nanoparticle synthesis lowers the efficiency of the biosynthetic process. An alternative option is the use of biogenic waste resources generated through the processing of agricultural wastes, food waste, vegetable scraps, etc. Plant wastes and biomass have poor nutritional quality and contribute to environmental contamination, but they are rich in flavonoids and hence can be employed as effective bioreductants during the green synthesis of various nanoparticles. Therefore, mostly used toxic chemicals like hydrazine hydrate (N 2 H 4 , H 2 O), sodium borohydride (NaBH 4 ), and dimethylformamides utilized for the reduction of metal ions may be replaced by greener alternatives of biogenic wastes. Biogenic waste is utilized as a stabilizing and reducing agent. Therefore, green synthesis of different nanostructures offers a great deal for their potential applications in different fields. However, most of the synthetic strategies are in the development stage. For practical applications of these processes, protocols need to be further modified and further research is required for the large-scale production of nanomaterials. This book chapter summarizes the benefits and drawbacks of biowaste-mediated nanoparticles and suggests potential advancements in the synthesis of metal and metal oxide nanoparticles.