Adsorptive Removal of Direct Azo Dyes from Textile Wastewaters Using Weakly Basic Anion Exchange Resin

Abstract

Direct dyes are still widely used for coloring a variety of materials due to their ease of use and the wide range of colors available at a moderate cost of production. In the aquatic environment, some direct dyes, especially the azo type and their biotransformation products, are toxic, carcinogenic and mutagenic. Hence the need for their careful removal from industrial effluents. It was proposed adsorptive retention of C.I. Direct Red 23 (DR23), C.I. Direct Orange 26 (DO26) and C.I. Direct Black 22 (DB22) from effluents using anion exchange resin of tertiary amine functionalities Amberlyst A21 (A21). Applying the Langmuir isotherm model, the monolayer capacities were calculated as 285.6 mg/g for DO26 and 271.1 mg/g for DO23. The Freundlich isotherm model seems to be the better one for the description of DB22 uptake by A21, and the isotherm constant was found to be 0.609 mg1−1/n L1/n/g. The kinetic parameters revealed that the pseudo-second-order model could be used for the description of experimental data rather than the pseudo-first-order model or intraparticle diffusion model. The dye adsorption decreased in the presence of anionic and non-ionic surfactants, while their uptake was enhanced in the presence of Na2SO4 and Na2CO3. Regeneration of the A21 resin was difficult; a slight increase in its efficiency was observed using 1M HCl, 1 M NaOH and 1 M NaCl solutions in 50% v/v methanol.

Handling heat‐stable salts in post‐combustion CO2 capture: A detailed survey

“…Several studies have been successful in removing different anions from waste water solutions using ion exchange procedures, e.g. chloride 123–126 . nitrate, 127–132 sulfate, 133–135 phosphate, 136–138 and acetate 123,139 .…”

“…[123][124][125][126] nitrate, [127][128][129][130][131][132] sulfate, [133][134][135] phosphate, [136][137][138] and acetate. 123,139 Ion exchange procedures present a chemically facile approach for alkanolamine reclamation, and its performance is deemed satisfactory for HSS removal with regards to its less chemical involvement, low energy requirement, and significantly suppressed solution foaming. 122,140 That notwithstanding, many drawbacks are still associated with the procedure.…”

Preparation of cellulose-based composite hydrogels for the removal of methylene blue

“…2 For example, it is estimated that 2%-20% of textile dyes are directly discharged as aqueous effluents, representing approximately 5000-10,000 tons of dyes per year. 3 One of the most used dyes in the textile industry to dye wool, cotton, and silk is methylene blue (MB). Methylene blue (Figure 1(a)) is a cationic and primary thiazine dye, which was first synthesized in 1800 by Heinrich Caro.…”

“…2 For example, it is estimated that 2%–20% of textile dyes are directly discharged as aqueous effluents, representing approximately 5000-10,000 tons of dyes per year. 3…”