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Open AccessArticle

Adsorptive Removal of Reactive Black 5 from Wastewater Using Bentonite Clay: Isotherms, Kinetics and Thermodynamics

Alamoudi Water Research Chair, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia
Author to whom correspondence should be addressed.
Academic Editor: Vincenzo Torretta
Sustainability 2015, 7(11), 15302-15318;
Received: 16 September 2015 / Revised: 2 November 2015 / Accepted: 13 November 2015 / Published: 18 November 2015
(This article belongs to the Section Sustainable Use of the Environment and Resources)
The studies of the kinetics and isotherms adsorption of the Reactive Black 5 (RB5) onto bentonite clay were explored in a batch study in a laboratory. The maximum RB5 adsorption conditions of bentonite clay were optimized such as shaking speed (100 rpm), temperature (323 K), pH (10), contact time (40 min), initial dye concentration (170 mg·L−1), and particle size (177 µm). The adsorbent surface was characterized using Fourier Transform Infrared Spectroscopy spectroscopy. The mechanisms and characteristic parameters of the adsorption process were analyzed using two parameter isotherm models which revealed the following order (based on the coefficient of determination): Harkin-Jura (0.9989) > Freundlich (0.9986) and Halsey (0.9986) > Langmuir (0.9915) > Temkin (0.9818) > Dubinin–Radushkevich (0.9678). This result suggests the heterogeneous nature of bentonite clay. Moreover, the adsorption process was chemisorption in nature because it follows the pseudo-second order reaction model with R2 value of 0.9998, 0.9933 and 0.9891 at 25, 75 and 100 mg·L−1 RB5 dye in the solution, respectively. Moreover, based on the values of standard enthalpy, Gibbs free energy change, and entropy, bentonite clay showed dual nature of exothermic and endothermic, spontaneous and non-spontaneous as well as increased and decreased randomness at solid–liquid interface at 303–313 K and 313–323 K temperature, respectively. View Full-Text
Keywords: bentonite clay; isotherms; kinetics; textile dye; Thermodynamics bentonite clay; isotherms; kinetics; textile dye; Thermodynamics
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Amin, M.T.; Alazba, A.A.; Shafiq, M. Adsorptive Removal of Reactive Black 5 from Wastewater Using Bentonite Clay: Isotherms, Kinetics and Thermodynamics. Sustainability 2015, 7, 15302-15318.

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