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Equilibrium and Kinetics of Color Removal from Dye Solutions with Bentonite and Polyaluminum Hydroxide
Author(s) -
Kacha S.,
Derriche Z.
Publication year - 2003
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143003x140782
Subject(s) - bentonite , adsorption , chemistry , hydroxide , wastewater , precipitation , kinetics , sodium hydroxide , flocculation , chemical engineering , inorganic chemistry , environmental engineering , organic chemistry , environmental science , physics , quantum mechanics , meteorology , engineering
Wastewater from the textile industry contains soluble dyes that are toxic and particularly difficult to remove. A promising low‐cost treatment, however, is use of polyaluminum hydroxide associated with bentonite. At suitable conditions, this process is able to efficiently remove color from solutions containing mixtures of soluble acid azo dyes and produce easily settleable sludge. The removal mechanism, which is believed to involve adsorption or precipitation and weak pH variations, is not well understood. With the overall reaction being second order, two elementary first‐order reactions could be assumed. The equilibrium removal is a decreasing function of the temperature. However, this effect is weak and decreases when the dye concentration increases. At usual values of concentration in textile wastewater, this effect can be neglected. The resulting solid compound is particularly resistant to mechanical stress. Moreover, color was significantly released at pH greater than 8. Sodium ions have no influence on the compound stability, which reinforces the assumption of the involvement of an adsorption process.