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Correction: Elias, M.; et al. 2015. Land Conversion Dynamics in the Borana Rangelands of Southern Ethiopia: An Integrated Assessment Using Remote Sensing Techniques and Field Survey Data. Environments 2015, 2, 1–31
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Environments 2015, 2(3), 388-398;

Comparative Sorption of Methylene Blue onto Hydrophobic Clays

Science Department, Borough of Manhattan Community College, The City University of New York, New York, NY 10007, USA
Bergen County Academies, Hackensack, NJ 07601, USA
Chemistry Department, College of Arts and Science, New York University, New York, NY 10003, USA
Author to whom correspondence should be addressed.
Academic Editor: Yu-Pin Lin
Received: 28 May 2015 / Revised: 27 July 2015 / Accepted: 28 July 2015 / Published: 5 August 2015
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Chemical modifications of clay to remove methylene blue (MB) from aqueous solutions at room temperature were compared. Natural bentonite (NC) was modified by cation exchange with hexadecyltrimethylammonium chloride (HC), bencyltriethylammonium chloride (BC), and tetramethylammonium chloride (TC) to reverse the surface polarity of the hydrophilic bentonite. The adsorption of MB was studied and fitted by the adsorption theories of Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin. Equilibrium parameters were calculated, indicating that chemical modification did not improve the adsorption, due to the electrostatic adsorption mechanism. Specific surface area was determined, reporting the following trend: NC > TC > BC > HC. Isotherms show that TC is the best modified clay for the adsorption of MB with a capacity of 217 mg/g. Adsorbents were characterized by SEM and the determination of their point zero charge, indicating a charge reversal at pH 9.5 and a heterogeneous surface that is optimum for the adsorption of molecules and ions onto their surfaces. View Full-Text
Keywords: adsorption; isotherm; methylene blue; modified clay; point zero charge adsorption; isotherm; methylene blue; modified clay; point zero charge

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Sponza, A.D.; Fernandez, N.J.; Yang, D.; Ortiz, K.A.; Navarro, A.E. Comparative Sorption of Methylene Blue onto Hydrophobic Clays. Environments 2015, 2, 388-398.

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