Fungal production: Nanobiocomposite for pollution control

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Ezine

  • Published: Oct 1, 2011
  • Author: David Bradley
  • Channels: UV/Vis Spectroscopy
thumbnail image: Fungal production: Nanobiocomposite for pollution control

Reduction, reduction

A whole raft of techniques, including UV-Vis spectroscopy has been used to characterise systematically biological composites containing silver-nanocrystals produced by the fungus Cylindrocladium floridanum in a novel, environmentally benign biological process. The biocomposite can rapidly degrade the widespread toxic pollutant nitrophenol.

Kannan Badri Narayanan and Natarajan Sakthivel of the Department of Biotechnology, at Pondicherry University, in Puducherry, India, explain how nitroaromatic compounds, such as nitrophenol, are among the largest and most important class of industrial chemicals. They find use in dye manufacture, as plasticizers, in pesticides and fungicides and as explosives. As such, they are widespread in the environment through deliberate and inadvertent release.

4-Nitrophenol (4-NP), which is highly stable and soluble in water, is one of the most critical of nitroaromatic compounds in this regard, especially as it is listed by the US Environmental Protection Agency as "priority pollutant". The ingestion of 4-NP leads to physiological problems because of the nitro group causing several blood disorders, hormonal imbalance, central nervous system poisoning, kidney and liver damage, the team adds. The compound is also a significant carcinogen and mutagen. 4-NP is also cytotoxic and can cause serious harm to the unborn fetus. As such, finding a straightforward and inexpensive, as well as efficient method of reducing or degrading this persistent material to less harmful substances for remediation of brownfield sites, water courses and ecosystems is needed urgently.

Degradation, that's the name of the game

Researchers have investigated oxidation, ozonylation, photocatalysis, sonication, ultraviolet and other means of breaking down 4-NP efficiently and effectively. Bioremediation with 4-NP metabolising microbes has also been studied.

Now, the Pondicherry team has devised a way to brew up a silver-nanoparticle biocompisite using Cy. floridanum that can heterogeneously catalyse the reduction of 4-NP, in the presence of the well-known reducing agent sodium borohydride, to the much less worrisome 4-aminophenol. The team used UV-Vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX) to study the particles. UV-Vis was used to monitor progress. TEM analysis of the fungal mycelia revealed the presence of the desired silver nanoparticles after culturing in an aqueous solution of silver nitrate at 30 Celsius for a week.

The UV-Vis spectra also allowed the team to extract the catalytic reaction kinetics in the reduction of 4-NP to 4-AP. "The reduction of organic pollutant, 4-NP followed pseudo-first-order kinetic model," the team concludes.


The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

 Structure built with ChemSpider - A whole raft of techniques, including UV-Vis spectroscopy has been used to characterise systematically biological composites containing silver-nanocrystals produced by the fungus Cylindrocladium floridanum in a novel, environmentally benign biological process. The biocomposite can rapidly degrade the widespread toxic pollutant nitrophenol.

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