Water pollution control is presently one of the major thrust areas of scientific research. While coloured organic compounds generally impart only a minor fraction of the organic load to wastewaters, their colour renders them aesthetically unacceptable. Stringent regulating measures are coaxing industries to treat their waste effluents to increasingly high standards. Colour removal, in particular, has recently become an area of major scientific interest as indicated by the multitude of related research reports. During the past two decades, several decolourization techniques have been reported, few of which have been accepted by some industries. There is a need to find alternative treatments that are effective in removing dyes and colourants from large volume of effluents, which are cost-effective, like the biological or integrated systems. This article reviews some of the widely used and most promising industrial wastewater decolourization methods. Data on decolourizing efficiencies of different causative agents, obtained by means of different physical, chemical and biological methods are discussed. Further a critical review is made on the various treatment methodologies and emerging technologies with a note on their advantages and disadvantages.

Decolourization of industrial effluents - available methods and emerging technologies - a review

In this article an effort has been made to review literature based on the role of peroxidases in the treatment and decolorization of a wide spectrum aromatic dyes from polluted water. Peroxidases can catalyze degradation/transformation of aromatic dyes either by precipitation or by opening the aromatic ring structure. Peroxidases from plant sources; horseradish, turnip, tomato, soybean, bitter gourd, white radish and Saccharum uvarum and microbial sources; lignin peroxidases, manganese peroxidases, vanadium haloperoxidases, versatile peroxidases, dye decolorizing peroxidases have been employed for the remediation of commercial dyes. Soluble and immobilized peroxidases have been successfully exploited in batch as well as in continuous processes for the treatment of synthetic dyes with complex aromatic molecular structures present in industrial effluents at large scale. However, recalcitrant dyes were also decolorized by the action of peroxidases in the presence of redox mediators.

Peroxidase mediated decolorization and remediation of wastewater containing industrial dyes: a review

Adhesive properties of polypropylene (PP) and polyethylene terephthalate (PET) film surfaces treated by DC glow discharge plasma

In the present work, Poly (ethylene terephthalate) films have been exposed to glow discharge air plasma to improve their surface properties for technical applications. Surface energy values have been estimated using contact angle value for different exposure times and different test liquids. Surface composition and morphology of the films were analyzed by XPS and AFM. Crystallinity of the plasma treated samples were studied by XRD analysis. The improvement in adhesive strength was studied by measuring T-peel strength and lap shear strength tests. It was found that the plasma treatment modified the surfaces both in chemical composition and morphology. Change of chemical composition made the polymer surfaces to be highly hydrophilic, which mainly depends on the increase in oxygen-containing groups. The AFM and XRD observation showed that the surface roughness and crystallinity of the PET film increased due to plasma treatment.

The effect of glow discharge plasma on the surface properties of Poly (ethylene terephthalate) (PET) film

Non-thermal plasma treatment for hydrophilicity improvement of grey cotton fabrics

A comparison between characteristics of various laser-based denim fading processes

Removal of the indigo color by laser beam–denim interaction

We proved in our experiments that the laser fading process removes efficiently indigo-dye from denim support. Differentlaser pulse parameters were used in order to obtain laser power density and fluence to start the ablation process. Thepurpose of this work is to determine the change of denim diffuse reflectivity spectra during laser irradiation with differentwavelength and different power density. The change of diffuse reflectivity coefficient was up to 17% at 450 nm wavelength(from 8% reflectivity for unirradiated denim). We use the beams from Nd:YAG laser (1064 nm and its second harmonic 532 nm) and CO2 lasers.Keywords: Ablation, Nd:YAG laser, CO2 laser, indigo-dyed denim. 1. INTRODUCTION The production of the discoloured jeans using conventional technologies has as the byproducts polluted water in largequantities.The alternate technologies in this field is the laser technology of fading dyed denim. The laser action on the colored denimfibers is mainly with the indigo color, by thermal effect.The process itself is based on the laser marking technology for textile material. A pair of high-speed computer controlledmirrors moves the laser beam on the denim material. The results are a uniform fading or a text or fading graphical image.The change between these types of fading is easy to do because the mirrors are controlled by computer. Also the computercontrols the laser beam parameters, adapting them to the various changes which appear during production process'. Variouslevels of color removal with little or no damage to the denim material are achieved by using different laser parameters.Advantages of laser-based finishing technology over other conventional processing techniques are: no pollution of theenvironment by reduction of chemical agents and water consumption; process flexibility allows replication of existingstonewash designs or creation of new finish styles; the finishing process can be applied on parts or assembled garments, oron uncut material as it is; by using the automated control of laser faded technology the manufacturers can change the finishstyle to another without retooling; micrographics cam be applied on the garment; special logos or characters can be appliedto denim products.In this paper we investigated the basic interaction of laser beam with indigo colored denim textile. The paper presents thechanges, which appear on the irradiated surface, evaluated by the measurement of diffuse reflectivity. We find the relationsbetween laser irradiation fluence, laser power density and the fading level.

Isaac Compean

Papers

A comparison between characteristics of various laser-based denim fading processes

Removal of the indigo color by laser beam–denim interaction

Removal of the indigo color by laser beam-denim interaction