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24 Biosynthesis of Nanoparticles Using Agriculture and Horticulture Waste

Biosynthesis of nanoparticles using agro-wastes such as Cocos nucifera coir [2],

corn cob [3], fruit seeds and peels [4], wheat bran [5], rice bran [6], and nut shells

[7] is reported in the literature. Plant-based resources are rich in tannins, steroids,

saponins, flavonoids, alkaloids, and other nutritional compounds [8]. These com-

pounds are responsible for reduction of metal ions into metal nanoparticles. They

are also present in various parts of plants such as stems, leaves, roots, barks, flow-

ers, shoots, and seeds. Plant extracts having these compounds are responsible for

reduction of metal ions and are capped on the surface of nanoparticles. Biosynthe-

sis of metal and metal oxide nanoparticles of required size and morphology has the

potential importance due to the size-dependent properties for various applications.

24.2

Agricultural and Horticultural Waste

Agriculture waste generated from various farming activities comprises of basic func-

tional moieties. These can be explored for the biosynthesis of nanoparticles. The agri-

cultural waste includes rice (straw, husk), corn (leaves, stalks, cobs, husks), coconut

(coir, pith, leaf), sugarcane (bagasse, leaf), banana (leaves, trunk, peels), pineap-

ple (pulp, core, plant, peel, crown), coffee pulp, mango (pulp, peel, rejects), tobacco

(reject leaves, midribs), abaca leaves, cocoa (core, pods), cassava (washings, peel,

leaves, trunk), peanut (reject beans, pods, plant), mung bean (reject beans, pods,

plant), areca nut (leaf, coir, shell), husk of rice, ragi, corn, cereals.

According to the International Society of Horticultural Sciences (ISHS), horticul-

ture includes the olericulture, cultivation of medicinal and aromatic plants, growing

fruits, floriculture, and arboriculture. Horticulture activity generates waste materials

such as stem, leaf, flower, peel, seeds, shells, pods of flowering plants, rejected flow-

ers, dried leaves, and vegetables. These wastes contain bioactive compounds such

as tocopherols, sterols, carotenoids, anthocyanins, flavonoids, cinnamic acids, and

phenolic acids [9]. Hence, horticulture waste has the potential to be channelized for

biosynthesis of nanoparticles.

24.3

Biosynthesis of Nanoparticle

To synthesize nanoparticles, dry form is more suitable, since it can be stored for

a long period of time. General steps involved in processing of waste, preparation of

metal salt solution, and biosynthesis of nanoparticles are highlighted with a practical

approach and examples (Figure 24.1).

24.3.1

Processing of Agriculture and Horticulture Waste

Agriculture and horticulture waste will either be in wet or dry form. Prior to using

it for nanoparticle synthesis, processing is an essential step. For long-term storage,

drying, powdering, and sieving are considered to be a suitable option. For the imme-

diate use of wet waste material, removing surface water is recommended. During the