| Autor: |
Barakat MA; Department of Environmental Sciences, Faculty of Meteorology, Environment and Arid Land Agriculture, King Abdulaziz University, Jeddah 21589, Saudi Arabia.; Central Metallurgical R & D Institute, Cairo 11421, Egypt., Selim AQ; Faculty of Earth Science, Beni-Suef University, Beni Suef 62511, Egypt., Mobarak M; Physics Department, Faculty of Science, Beni-Suef University, Beni Suef 62511, Egypt., Kumar R; Department of Environmental Sciences, Faculty of Meteorology, Environment and Arid Land Agriculture, King Abdulaziz University, Jeddah 21589, Saudi Arabia., Anastopoulos I; Department of Chemistry, University of Cyprus, P.O. Box 20537, Nicosia Cy-1678, Cyprus., Giannakoudakis D; Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland., Bonilla-Petriciolet A; Departamento de Ingeniería Química, Instituto Tecnológico de Aguascalientes, Aguascalientes 20256, Mexico., Mohamed EA; Faculty of Earth Science, Beni-Suef University, Beni Suef 62511, Egypt., Seliem MK; Faculty of Earth Science, Beni-Suef University, Beni Suef 62511, Egypt., Komarneni S; Department of Ecosystem Science and Management and Materials Research Institute, 204 Energy and the Environment Laboratory, The Pennsylvania State University, University Park, PA 16802, USA. |
| Abstrakt: |
Manganese-containing mica (Mn-mica) was synthesized at 200 °C/96 h using Mn-carbonate, Al-nitrate, silicic acid, and high KOH concentration under hydrothermal conditions. Mn-mica was characterized and tested as a new adsorbent for the removal of methyl orange (MO) dye from aqueous solutions. Compared to naturally occurring mica, the Mn-mica with manganese in the octahedral sheet resulted in enhanced MO uptake by four times at pH 3.0 and 25 °C. The pseudo-second order equation for kinetics and Freundlich equation for adsorption isotherm fitted well to the experimental data at all adsorption temperatures (i.e., 25, 40 and 55 °C). The decrease of Langmuir uptake capacity from 107.3 to 92.76 mg·g -1 within the temperature range of 25-55 °C suggested that MO adsorption is an exothermic process. The role of manganese in MO selectivity and the adsorption mechanism was analyzed via the physicochemical parameters of a multilayer adsorption model. The aggregated number of MO ions per Mn-mica active site ( n ) was superior to unity at all temperatures signifying a vertical geometry and a mechanism of multi-interactions. The active sites number ( D M ) of Mn-mica and the total removed MO layers ( N t ) slightly changed with temperature. The decrease in the MO adsorption capacities ( Q sat = n·D M · N t ) from 190.44 to 140.33 mg·g -1 in the temperature range of 25-55 °C was mainly controlled by the n parameter. The results of adsorption energies revealed that MO uptake was an exothermic (i.e., negative Δ E values) and a physisorption process (Δ E < 40 kJ mol -1 ). Accordingly, the adsorption of MO onto Mn-mica was governed by the number of active sites and the adsorption energy. This study offers insights into the manganese control of the interactions between MO ions and Mn-mica active sites. |
