I am trying to synthesize metal (Fe, Cu, Zn) oxide nanoparticles by aqueous extraction of fruit peels (watermelon, orange, etc.) and coffee grounds.
When synthesizing the nanoparticles, I found that pH is an important factor, so I decided to use a I have been mixing fruit peel, coffee extract with the metal solution, adjusting the pH to 7-12 and heating, stirring in an evaporator (for simple stirring, not for solvent concentration), but the results have been disappointing.
In particular, copper oxide particles do not seem to form properly.
My questions are several
1. is adjusting the pH correct for green synthesis (using HCl, NaOH)? I have already experienced that if I don't adjust the pH, nothing is formed, what should I do in this case?
2. is it appropriate to use fruit peel extract? I have seen many papers using mainly leaf extract.
3. what is the absorption spectrum of the green synthesized copper oxide nanoparticles in UV-vis?
I am asking these questions because there is no researcher around me who has done the same experiment. I look forward to your valuable answers.
Sincerely
The three foremost conditions for the synthesis of nanoparticles are the selection of green or environment-friendly solvent, a good reducing agent, and a harmless material for stabilization. For the synthesis of nanoparticles, extensive synthetic routes have been applied in which physical, chemical, and biosynthetic routes are very common. Generally, the chemical methods used are too expensive and incorporate the uses of hazardous and toxic chemicals answerable for various risks to the environment (Nath and Banerjee 2013). The biosynthetic route is a safe, biocompatible, environment-friendly green approach to synthesize nanoparticles using plants and microorganisms for biomedical applications (Razavi et al. 2015). This synthesis can be carried out with fungi, algae, bacteria, and plants, etc. Some parts of plants such as leaves, fruits, roots, stem, seeds have been used for the synthesis of various nanoparticles due to the presence of phytochemicals in its extract which acts like stabilization and reducing agent (Narayanan and Sakthivel 2011). For nanoparticle synthesis, numerous biological and physicochemical pathways fall under two discrete classes: a bottom-up and top-down approach.
Temesgen Geremew I would like to comment on 'Generally, the chemical methods used are too expensive and incorporate the uses of hazardous and toxic chemicals answerable for various risks to the environment', a statement I feel is somewhat misleading. In the production of metal colloids the most dangerous or toxic item is the metal precursor itself - chloroplatinic acid, cuprammonium compounds, silver nitrate and so on. Many reduction routes involve inexpensive reagents e.g. H2 (product is water), hydrazine hydrate (products are water and nitrogen). Silver salts can be reduced by light alone (e.g. photography), while most gold compounds easily reduce at room temperature under a variety of scenarios.
Hj Kam In terms of natural products then the key concern is the presence of an appropriate reducing agent or agents. This reduction process is invariably pH dependent, as you say. The amount, type, and quality of the reducing agent(s) almost certainly will vary with season and the type of 'natural product' selected. Note that 'natural' does not necessarily mean 'healthy' - belladonna and snake venom being 2 trivial examples. Both are natural products but certainly not healthy!
Thank you Alan F Rawle and Temesgen Geremew for the this wonderful explanations.
Hi Hj Kam
Various types of green synthesis process have been reported till date but the phase pure synthesis is very tuff. The 1st collected materials are generally more amorphous in nature (obtained from the XRD analysis). The phase pure green synthesis of nanoparticles is also a great challenge as far my concern.
Regards
Hello, you must try many trials by adjusting the conditions including concentration, pH, temperature to successfully green synthesis Nps. The green synthesis is not standard protocol but differ by the nature of natural sources
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