Nelson Durán

Bio: Nelson Durán is an academic researcher from State University of Campinas. The author has contributed to research in topics: Silver nanoparticle & Effluent. The author has an hindex of 76, co-authored 547 publications receiving 24748 citations. Previous affiliations of Nelson Durán include Valparaiso University & Universidade de Mogi das Cruzes.

Mechanistic aspects of biosynthesis of silver nanoparticles by several Fusarium oxysporum strains.

Abstract: Extracellular production of metal nanoparticles by several strains of the fungus Fusarium oxysporum was carried out It was found that aqueous silver ions when exposed to several Fusarium oxysporum strains are reduced in solution, thereby leading to the formation of silver hydrosol The silver nanoparticles were in the range of 20–50 nm in dimensions The reduction of the metal ions occurs by a nitrate-dependent reductase and a shuttle quinone extracellular process The potentialities of this nanotechnological design based in fugal biosynthesis of nanoparticles for several technical applications are important, including their high potential as antibacterial material

Potential applications of oxidative enzymes and phenoloxidase-like compounds in wastewater and soil treatment: a review

Abstract: A number of oxidative enzymes from bacteria, fungi and plants have been reported to play an important role in numerous waste treatment applications. Peroxidases and/or phenoloxidases can act on specific recalcitrant pollutants by precipitation or transforming to other products and permitting a better final treatment of the waste. Improvement in the useful life and thereby a reduction in treatment cost has been accomplished through enzyme immobilization. Horseradish peroxidase, lignin peroxidase and manganese peroxidase mineralize a variety of recalcitrant aromatic compounds. Immobilization of these enzymes on porous ceramic supports or resins did not adversely affect their stability and showed a good potential for degradation of environment persistent aromatics. Tyrosinase, which catalyzes the hydroxylation of phenols and dehydrogenation of o-diphenols, in an immobilized form exerted an excellent phenol removal. Laccase is capable of eliminating the phenols through polymerization process, however, the presence of mediator such as ABTS and HBT degraded phenol by oxidative process. Many applications with oxidative enzymes and plant materials in effluent as in soil remediation will be discussed.

Antibacterial Effect of Silver Nanoparticles Produced by Fungal Process on Textile Fabrics and Their Effluent Treatment

Abstract: Microorganisms play an important role in toxic metal remediation through reduction of metal ions. Studies demonstrated that silver ions may be reduced extracellularly using Fusarium oxysporum to generate stable gold or silver nanoparticles in water. These particles can be incorporated in several kinds of materials such as cloths. These cloths with silver nanoparticles are sterile and can be useful in hospitals to prevent or to minimize infection with pathogenic bacteria such as Staphylococcus aureus. In this work, the extracellular production of silver nanoparticles by F. oxysporum and its antimicrobial effect when incorporated in cotton fabrics against S. aureus were studied. In addition, all effluent was bioremediated using treatment with C. violaceum. The results showed that cotton fabrics incorporated with silver nanoparticles displayed a significant antibacterial activity against S. aureus. The effluent derived from the process was treated with C. violaceum and exhibited an efficient reduction in the silver nanoparticles concentration. In conclusion, it was demonstrated the application of biological synthesis to silver nanoparticles production and its incorporation in cloths, providing them sterile properties. Moreover, to avoid any damage to the environment the effluent containing silver nanoparticles can be treated with cyanogenic bacterial strains.

TiO2-assisted photocatalytic degradation of azo dyes in aqueous solution: kinetic and mechanistic investigations A review

Abstract: The photocatalytic degradation of azo dyes containing different functionalities has been reviewed using TiO2 as photocatalyst in aqueous solution under solar and UV irradiation. The mechanism of the photodegradation depends on the radiation used. Charge injection mechanism takes place under visible radiation whereas charge separation occurred under UV light radiation. The process is monitored by following either the decolorization rate and the formation of its end-products. Kinetic analyses indicate that the photodegradation rates of azo dyes can usually be approximated as pseudo-first-order kinetics for both degradation mechanisms, according to the Langmuir–Hinshelwood model. The degradation of dyes depend on several parameters such as pH, catalyst concentration, substrate concentration and the presence of electron acceptors such as hydrogen peroxide and ammonium persulphate besides molecular oxygen. The presence of other substances such as inorganic ions, humic acids and solvents commonly found in textile effluents is also discussed. The photocatalyzed degradation of pesticides does not occur instantaneously to form carbon dioxide, but through the formation of long-lived intermediate species. Thus, the study focuses also on the determination of the nature of the principal organic intermediates and the evolution of the mineralization as well as on the degradation pathways followed during the process. Major identified intermediates are hydroxylated derivatives, aromatic amines, naphthoquinone, phenolic compounds and several organic acids. By-products evaluation and toxicity measurements are the key-actions in order to assess the overall process.