Dye removal by immobilised fungi.

Dyes used in the coloration of textiles, paper, and other products are highly visible, sometimes toxic, and sometimes resistant to biological breakdown; thus it is important to minimize their release into aqueous environments. This review article considers how biosorption of dyes onto cellulose-related materials has the potential to address such concerns. Numerous publications have described how a variety of biomass-derived substrates can be used to absorb different classes of dyestuff from dilute aqueous solutions. Progress also has been achieved in understanding the thermodynamics, kinetics, and chemical factors that control the uptake of dyes. Important questions remain to be more fully investigated, such as those involving the full life-cycle of cellulosic substrates that are used for the collection of dyes. Also, more work needs to be done in order to establish whether biosorption should be implemented as a separate unit operation, or whether it ought to be integrated with other water treatment technologies, including the enzymatic breakdown of chromophores.

https://ojs.cnr.ncsu.edu/index.php/BioRes/article/download/BioRes_06_2_2161_Hubbe_HD_Removal_Pollutants_Review_Pt1_Metals/1901

Cellulosic substrates for removal of pollutants from aqueous systems: a review. 1. metals

Decolourization of reactive black 5 by laccase: Optimization by response surface methodology

Production of laccase enzyme for their potential application to decolorize fungal pigments on aging paper and parchment

Decolourization potential of white-rot fungus Phanerochaete chrysosporium on synthetic dye bath effluent containing Amido black 10B

Although a non-sterile, undiluted carpet dye effluent (containing two anthraquinone dyes) did not support growth of Trametes versicolor, the pre-grown fungus removed 95% of its color in shake-flasks after 10 h of incubation. After decoloration, the COD of the cell-free supernatant increased and the toxicity was unchanged as determined by the Microtox assay using Vibrio fischeri. Decoloration rates decreased when either glucose alone or Mn2+ and glucose were added. T. versicolor, immobilized on jute twine in a rotating biological contacting reactor, also decolorized four successive batches of the effluent. There was no decoloration in any of the uninoculated, non-sterile controls.

Decoloration of a carpet dye effluent using Trametes versicolor.

Plasma electrolytic oxidation (PEO) is a surface-treatment process extensively used to protect the surfaces of light metals such as Mg, Al, and Ti. Here, we report an environmentally friendly PEO process that uses nitrogen-containing electrolytes and low voltages (120 V) to form ~ 12 micron thick, uniform, adherent and porous oxide coatings on T1 titanium alloy surfaces. We evaluated the influence of nitrogenation by comparing the coatings to alloys treated in PEO baths without nitrogen-containing compounds. Both sets of samples exhibited basalt-like morphologies with distinct variation in the pore structures. The composition analyses showed that the coatings were primarily composites of titanium oxides and silicates. The T1 Ti alloys treated with nitrogen-containing electrolytes also contained TiC and TiN. This is the first ever report of producing TixOy, Ti-Si-O, TiC, and TiN composite coatings using a single PEO bath without carbide/nitride nanoparticles. The bandgaps of the coatings suggested visible light functionality. The use of nitrogen-based compounds in the PEO baths improved the hardness of the oxide layers but introduced stress-induced cracking which are potentially responsible for the reduction in corrosion resistance of the nitride and carbide containing coatings. 

/pdf/low-voltage-environmentally-friendly-plasma-electrolytic-3gcanuev.pdf

Low voltage environmentally friendly plasma electrolytic oxidation process for titanium alloys

/pdf/low-voltage-environmentally-friendly-plasma-electrolytic-33vcs9vq.pdf

Low-density metals such as Mg and Al (and their alloys) are of high interest for lightweight engineering applications in various industries. Moisture sensitivity, poor tribology, and corrosion susceptibility limit the direct application of these light metals. Plasma electrolytic oxidation (PEO) is extensively used to passivate light metals against corrosion and enhance their mechanical properties. PEO processes in current use are often energy-intensive and use toxic electrolytes. Incorporating composite characteristics to PEO-treated surfaces typically requires modification of electrolytes with nanoparticle addition. Some applications also need post-treatment of oxidized coatings to ensure functionality. We report a versatile, environmentally friendly PEO process that uses organo-silicate electrolytes enriched with nitrogen-containing solutions. The single-step process produces ∼6 μm thick, uniform, adherent, and porous oxide coatings on AZ80 and Al6061 surfaces in 15 min. We evaluated the influence and effectiveness of in situ nitridation by comparing the coating properties with those on alloys treated in PEO electrolytes without nitrogen-containing chemicals. The two sets of coatings were porous with multilayered basalt-like topographies and were composed of metal oxides and metal silicates. Alloys treated in nitrogen-containing electrolytes exhibited the presence of oxynitrides. The use of nitrogen-containing PEO electrolytes resulted in coatings with enhanced mechanical behavior. We found that the corrosion resistance of coatings prepared using low voltages in this study was comparable to the traditional PEO-treated coatings reported in the literature. Nitridation of the coatings, however, appears to have a slightly negative influence on the coatings’ corrosion resistance. Our future work will focus on improving the corrosion resistance of the mechanically resilient, nitride-containing PEO-treated coatings.

Chris Goode

Papers

Decoloration of a carpet dye effluent using Trametes versicolor.

Low voltage environmentally friendly plasma electrolytic oxidation process for titanium alloys

Low voltage environmentally friendly plasma electrolytic oxidation process for titanium alloys

Protecting Light Metal Alloys Using a Sustainable Plasma Electrolytic Oxidation Process