https://www.ircwash.org/sites/default/files/341.0-97DY-15639.PDF

Dye removal using low cost adsorbents

Adsorption of hazardous dye crystal violet from wastewater by waste materials.

Color, which contributes so much to the beauty of Nature, is essential to the attractiveness and acceptability of most products used by modern society [1]. As long ago as the 25th century BC man colored his surroundings and clothes using a limited range of natural colorants of both animal and vegetable origin. Alizarin (18)1 extracted as the glycoside rubierythric acid from madder, was used by the ancient Egyptians and Persians, the use of indigo (16) obtained from Indigofera dates back to 3000 BC, and Tyrian Purple (6,6′-dibromoindigo), prepared from the sea snail Murex brandaris, has been used since the Roman era. However, the preparation in 1856 of the first synthetic dyestuff, mauveine (12), by Perkin gave birth to the development of many other important sectors of the modern chemical industry. Compared with natural dyestuffs, synthetic colorants are better able to meet the increasingly rigorous technical demands of the present day in terms of stability, fastness, etc. Color can add not only aesthetic appeal, but frequently provides an almost irreplaceable safety feature (traffic lights and signs, drug identification, control systems) [2].

Organic Dyes and Pigments

In the electrocoagulation of Drimarene Discharge X-3LG® (R12S) and Samaron Yellow 4® (D05H), the effects of sacrificial anodes, initial pH, rate of stirring and concentrations of dyes on the fraction of decolourization were tested. The experimental results revealed that the colour of dyes in the aqueous phase was effectively removed when iron and aluminium were used as sacrificial anodes and the concentration of the dyes was less than 100 p.p.m. When the concentration of R12S exceeded 300 p.p.m. iron was a more suitable sacrificial anode for electrocoagulation of R12S than aluminium. For the electrocoagulation of D05H in aqueous solution aluminium as a sacrificial anode was superior to iron when the concentration of D05H exceeded 300 p.p.m. Using iron as sacrificial anode, the residual concentration fraction of R12S was decreased below 10% when the initial concentration of R12S and charge passed were 500 p.p.m. and 120C, respectively. The decolourization fraction of D05H was 99% when aluminium was used as sacrificial anode.

Decolourization of dye-containing solutions by electrocoagulation

In this study, the adsorption of an industrial dye Supranol Yellow 4GL onto Cetyltrimethylammonium-bentonite (CTAB-bentonite) is investigated. The organobentonite is synthesised by exchanging cetyltrimethylammonium cations (CTAB) with inorganic ions on the surface of bentonite. The adsorption of Supranol Yellow 4GL onto organobentonite is found to be maximum when the concentration of CTAB exchanged is 100% according to the cation exchange capacity of the clay (CEC). The modification of organobentonite is examined using XRD and FTIR techniques.

Adsorption study of an industrial dye by an organic clay

The paper considers the use of water and chemicals in the textile industry and the volume, nature and composition of process effluents, the effect they have on the environment and the limitations they pose on the reuse of water.



An outline is given of the methods available for treatment of waste waters from the industry, on site or at a Water Authority's works and the effects that chemical constituents of the effluents have on the treatment processes and on disposal of water and sludge.



The assessment and significance of biodegradability and the extent of present-day knowledge on the biodegradability of the main classes of chemicals used in textile processing are discussed.



The paper concludes with a section dealing with the removal of colour from waste waters.

Deirdre K. Gardiner

Papers

Textile Waste Waters: Treatment and Environmental Effects