Biotechnology for Zero Waste – Emerging Waste Management Techniques (Chaudhery Mustansar Hussain (editor) etc.)

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24 Biosynthesis of Nanoparticles Using Agriculture and Horticulture Waste

Table 24.1

Waste material used in the biosynthesis of nanoparticles.

Waste material

Speciﬁcation

Operation

Storage

References

Cocoa pod shell

Has high moisture Material need to

be cut to small

pieces, dried

under sunlight,

powdered and

sieved

At 4 ^∘C

[10]

Leaves

Washing and

drying

Can be powdered

or made to small

pieces

Room

temperature in

airtight containers

[11]

Flowers

Washing and

drying

Diced into pieces

and drying under

appropriate

sunlight

Stored in airtight

containers

[11]

Fruit peel

Washing and

drying

Cut into small

pieces and either

shade dried or

sunlight

Stored in airtight

containers

[12]

preparation of the extract, the waste needs to be powdered, transferred to distilled

water, boiled, and filtered. Table 24.1 specifies the waste material that can be used

in the biosynthesis of nanoparticles and its various features necessary to be followed

when used for any experimental purpose. General procedure of preparing metal salt

solution, extract from waste material, and storage is mentioned in Table 24.2.

24.3.2

Synthesis of Nanoparticles

Metal salt solutions of known concentration are mixed with extract obtained from

the waste sources and heated in a water bath or kept in a shaker at room temperature

till the color changes. During the heating process, the metal ions and its respective

functional moieties will have interaction in a short period of time. Also a change in

color is an indicator of nanoparticle synthesis. For the synthesis of nanoparticles at

room temperature, metal salt solution should be mixed with the extract and is kept

under vortex in an orbital shaker for a long period of time. This enhances the inter-

action between metal ions and functional moieties present in the solution triggering

reduction of metal ions. Periodically, surface plasmon resonance (SPR) is recorded

using UV spectrophotometer that is essential in monitoring the SPR values. Vortex

of the extract with salt solution leads to the reduction of metal ions. As the SPR

value increases, the reduction reaction of ions will reduce accordingly indicating

the completion of the process.

24.3.3

Separation of Nanoparticles

The separation of nanoparticles is followed with centrifugation with a suitable rpm

maintained at a fixed temperature. The supernatant is discarded, and the pellet is