Alenka Majcen Le Marechal

Comparison of H2O2/UV, H2O2/O3 and H2O2/Fe2+ processes for the decolorisation of vinylsulphone reactive dyes

Six vinylsulphone reactive dyes were decolorised using three oxidation processes (H2O2/UV, H2O2/O3 and H2O2/Fe2+). The efficiency of decolorisation was measured by decolorisation time, absorbance, COD and TOC and the three methods of decolorisation are compared.

The use of experimental design for the evaluation of the influence of variables on the H2O2/UV treatment of model textile waste water

The evaluation of the influence of variables (NaOH, NaCl, urea, intensity of UV irradiation, concentration of H2O2 and decoloration time) on the H2O2/UV treatment of textile waste waters by the use of experimental design is described. Experimental design is used to establish which variables influence in the positive or negative sense the efficiency of the decoloration process. A model waste water, polluted with a reactive vinylsulphone dye with C.I. Reactive Black 5 and dye-bath additives was used for the decoloration. Influences were determined by the measurement of absorbance, COD and TOC.

The use of artificial neural network (ANN) for modeling of the H2O2/UV decoloration process: part I

Abstract A brief introduction into artificial neural networks (ANNs) is given, with emphasis on counter-propagation learning strategy, as well as their use for the purpose of modeling and optimization of H 2 O 2 /UV decoloration process. The use of Plackett–Burman partial factorial design for seven variables on three different levels, for the selection of experiments, needed to calculate the significance of variables, is described. Results of learning with Kohonen ANN are described, and the best prediction assembly suggested.

The study of the effects of the variables on H2O2/UV decoloration of vinylsulphone dye: part II

Abstract As a continuation of part I [Dyes and Pigments 42 (1999), 123] where modeling of H2O2/UV decoloration of monochlorotriazine azo dye C.I. Reactive Red 120 was discussed, this part deals with the study of the effects of the variables on H2O2/UV decoloration of reactive vinylsulpone dye C.I. Reactive Blue 19. Influence of chemicals (NaOH, NaCl, urea), added to the dye-bath for dyeing with stated colorant, as well as the influence of reaction conditions (intensity of UV irradiation, concentration of hydrogen peroxide and decoloration time) is described. Influences were determined by the measurement of ecological parameters: absorbance, COD, TOC and TIC.

Textile Finishing Industry as an Important Source of Organic Pollutants

The textile finishing industry is, among all industries in Europe, the greatest consumer of high quality fresh water per kg of treated material and with the natures of their production processes significantly contributing to pollution. Wastewater from the textile industry is also a significant environmental pollution source of persistent organic pollutants. Not only textile wastewater but also textile products often contain chemicals such as formaldehyde, azo-dyes, dioxins, pesticides and heavy metals, that might pose a risk to humans and the environment. Some of these chemicals found in finished products are there as residues from the production of dyes and auxiliary chemicals (the synthesis of dyes involves a large variety of chemicals with complex synthesis paths, during which toxic, carcinogenic and persistent organic compounds can be formed, such as dioxins, and traces can be found in commercial dyes), others are added to give certain characteristics to the products (colour, flame retardancy, anti wrinkling properties etc.) (Križanec & Majcen Le Marechal, 2006), or are already present in the raw textile material. The mentioned compounds have been found in wastewater after home washing, in organic solvent after dry-cleaning and also in the atmosphere after incineration. Possible sources of organic pollutants are also wastewater treatment methods and the incineration of textile materials. The formation of dioxins can occur via dyeing and textile finishing processes with conditions favourable for their generation (high temperature, alkaline conditions, ultraviolet (UV) radiation, and other radical initiators). Textile dyes are designed to be resistant to microbial, chemical, thermal and photolytic degradation. After the dyeing process, a lot of non-bonded dyes are released into the wastewater, which can also be treated by Advanced Oxidation Processes (AOPs) in order to destroy the dye molecule and to decolourise the wastewater and reduce organic pollution. It is well-known that under the experimental conditions of such methods, which can be very useful because of the short-time of treatment, hazardous compounds can be formed due to very powerful oxidizing agents such as hydroxyl radicals (OH). In line with the improvement of people’s living standard and the growing awareness and need to preserve the environment several regulations were introduced also in the textile industry in order to control the use of chemicals in textile processes. Under REACH regulation (REACH regulation controlled the quality of fabric, apparels, and shoes

Novel N-chlorinated derivatives of 2H-1-benzopyran-2-imines

A series of new N-chlorobenzopyran-2-imines were prepared in moderate to good yields, by reacting sodium hypochlorite in an acidic medium with benzopyran-2-imines obtained via the Knoevenagel condensation. Some of the N-chlorobenzopyran-2-imines obtained are potential antiproliferating agents.

Reaction of dicyano epoxides with thiocyanate ion: route to α-thiocyanato derivatives or to 2-acetylimino-1,3-oxathioles and X-ray crystal structure of 2-acetylimino-4-(4-tolyl)-1, 3-oxathiole-5-carbonitrile

β-Aryl dicyano epoxides reacted as synthetic equivalents of ketene dications with KSCN in aq. dimethyl sulfoxide or EtOH, or with NH4SCN in acetonitrile, to give α-thiocyanato derivatives. When Ac2O was used as a solvent, the 1,3-oxathiolane intermediates were trapped as 2-acylimino-1,3-oxathioles. This new synthetic route to 1,3-oxathioles was extended to 1,3-oxaselenoles by using KSeCN as the reactant in Ac2O. The crystal structure of an important intermediate compound, 2-acetylimino-4-(4-tolyl)-1,3-oxathiole-5-carbonitrile, was determined by means of X-ray diffraction.

Feasibility study of ultrasound as water disinfection technology

AbstractThis article presents a section of project work related to the use of ultrasound technology as an eco-friendly water disinfection process. Scientific and economical evaluations are presented for two different ultrasound systems. The effects of ultrasound frequencies (20, 279 and 817 kHz), amplitude (acoustic power) and the treatment time for bacteria survival were studied. Experiments performed on a laboratory scale using two biological indicator micro-organisms Bacillus subtilis and Escherichia coli indicated that disinfection efficiency is affected by bacteria morphology, ultrasound frequencies and energy densities entering the system. As the spore-forming bacteria B. subtilis seemed less vulnerable to ultrasound exposure, a significant E. coli inhibition of 2.97 ± 0.58 log was achieved in 5 min treatment time at 817 kHz.

First stable α-diols and hemiketals from the α-halo pyruvamide series

Abstract The addition of water or alcohol to 3-halopyruvamides, having a special interest in enzymology, permitted us to isolate stable α-diols and hemiketals, until then detected only by spectroscopic means. The reaction is not diastereoselective, but selective precipitation of only one diastereoisomer shifts the equilibrium between the two isomers. Isolated compounds were fully characterised and results discussed.

Free Formaldehyde Determination Using HPLC

Release of formaldehyde from durable press treated fabrics is a problem for human health and safety because formaldehyde is suspected to be carcinogen. The accuracy of the standard test method for the free formaldehyde determination, Japan Law 112, depends on the formaldehyde content of the sample. The formaldehyde contents below 20 μg/g cannot be shown to be caused by formaldehyde. The detection of low formaldehyde contents is important particularly in some fields, like children clothing, so the High Performance Liquid Chromatography was used. With different crosslinking reagents finished textile substrates were extracted with water to detect the free formaldehyde by an acetylacetone method. The results obtained by the standard test method, Japan Law 112, where UV/VIS spectrometer was used, were compared with the results obtained by HPLC method where separation was performed on RP C 18 column with water: MeOH as a mobile phase. It was shown that the detection limit and limit of quantification were improved using HPLC method. Concentration range obtained by HPLC method is from 0.3 μg/g to 3000 μg/g.