With excellent electrical and thermal conductivities, carbon nano-onions (CNOs), a type of carbon nanostructure, have a variety of uses in biomedicine, bioimaging, energy conversion, and electronics.
However, the traditional methods for producing them are very complex, toxic, and energy-intensive.
Fortunately, using microwave pulses and waste fish scales, scientists have now discovered a practical and environmentally friendly way to recreate high-quality CNOs.
This innovative strategy might pave the way for CNO adaptation in the next technologies.
Free amino acids, like taurine and creatine, which are frequently used to make sports drinks, food supplements, infant formula, and medications, can also be found in fish waste.
Carbon-based nanomaterial created in fish waste
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Admittedly, there are some significant disadvantages to using traditional methods to make CNOs.
Some also demand a significant amount of effort while some call for difficult synthesis conditions like high temperatures or vacuum, as per ScienceDaily.
Some methods can overcome these restrictions, but they necessitate sophisticated catalysts, pricey carbon sources, or hazardous acidic or basic environments. This severely restricts CNOs' potential.
A group of researchers from Japan's Nagoya Institute of Technology discovered an easy and practical method to convert fish waste into incredibly high-quality CNOs.
The group, which also included Associate Professor Takashi Shirai, Master's student Kai Odachi, and Assistant Professor Yunzi Xin, created a method of synthesis in which fish scales, which are removed from fish waste after cleaning, are quickly transformed into CNOs by microwave pyrolysis.
The CNOs produced by this synthesis process have very high crystallinity. This is incredibly challenging to accomplish in processes that start with biomass waste.
The CNOs' surfaces are also thoroughly and selectively functionalized with (COOH) and (OH) groups during synthesis.
Comparing this to the conventionally prepared CNOs, where the surface is typically bare and needs to be functionalized through extra actions.
The team showed how their CNOs were used in LEDs and thin films that emit blue light as examples of one of the numerous practical uses for their CNOs.
Both inside solid devices and when distributed in a variety of solvents, such as water, ethanol, and isopropanol, the CNOs formed a highly stable emission.
Additionally, the suggested synthesis method offers an easy way to transform fish waste into infinitely more beneficial materials while also being environmentally friendly.
Skin, head, fins, frames, and viscera are among the FPH derived from fish waste material. In general, fatty fish, which have dark meat, have been compared to lean fish in use for FPH. Dark meat's capacity to oxidize lipids has a detrimental effect (Chalamaiah et al., 2012), as per ScienceDirect.
The preparation of FPH from the waste product of fish skin accounted for a large portion of the work. The protein hydrolysate from various species of fish skin has been the subject of several studies.
Giannetto et al. (2020) examined the molecular weight distribution of the protein hydrolysate made from Engraulis encrasicolus waste and found that it helps to reduce mediator protein expression while also protecting against inflammation.
To assess the functional (water holding capacity, emulsion capacity, and oil binding properties) and rheological properties of the protein hydrolysate, Yin et al. (2010) prepared the hydrolysate from the catfish skin.
They concluded that the treatment of various enzymes increased the protein hydrolysate of catfish skin's viscoelastic properties, yield color characteristics (light yellow), and proximate composition (protein, ash, and moisture).
According to Sampath Kumar et al. (2011), skin from croaker (O. ruber) and horse mackerel (M. cordyla) was used to make protein hydrolysate while pepsin and trypsin were present.
In 2013, Nazeer and Deeptha looked at the enzymatic hydrolysis of protein hydrolysate from the skin of ribbon fish and sheela fish (S. barracuda) (L. savala). They discussed the hydrolysates' ability to fight free radicals and their amino acid composition.
The functional and antioxidative qualities of the protein hydrolysate extracted from the skin of striped catfish were reported by anuja et al. in 2014. (P. hypophthalmus).
Alcalase enzyme managed to improve the degree of hydrolysis of the developed protein hydrolysate and is crucial for boosting the antioxidant and functional properties.
