Abstract
Highly ordered pure MCM-41 and In-MCM-41 mesoporous adsorbents (with Si/In = 95 (IM0.05) and Si/In = 90 (IM0.1)) were synthesized using the hydrothermal-assisted method. The structural, morphological and texture characteristics were investigated by XRD, N2 adsorption–desorption, SEM-EDX, TEM, diffuse reflectance (DR) and FTIR. The broadening XRD diffraction peaks as well as the shifts to higher and lower 2-theta in IM0.05 and IM0.1, respectively, confirmed the incorporation of indium atoms in the MCM-41 structure. SEM-EXD and TEM images showed that pure MCM-41 and IM0.05 preserve a highly long-range well-ordered hexagonal pore structure, on the other hand, high loading of indium (IM0.1) resulted in partially irregular pore-ordering and morphological defects related to a partial dissolution of MCM-41 structure. The infrared spectra of In-incorporated samples showed a decrease in the transmittance intensity of MCM-41 characteristic peaks with little shifts relative to the pure MCM-41 sample. The potential of pure MCM-41 and In-MCM-41 samples for adsorption of dyes was preliminarily investigated. The removal efficiency of both methylene blue and basic yellow-28 (BY28) was enhanced by the incorporation of indium in the MCM-41. The adsorption equilibrium data of BY28 dye on pure, IM0.05 and IM0.1 samples fitted well with Langmuir adsorption model with adsorption capacity of 123.46, 156.99 and 158.48 mg g−1 respectively. The calculated free adsorption energy obtained from D–R isotherm was found to be 26.7 kJ mol−1 referring to that the adsorption of BY28 on IM0.05 adsorbent is chemical. The adsorption kinetic of BY28 on IM0.05 sample followed the pseudo-second-order model. The adsorption experiments revealed that the prepared samples can be used as effective adsorbents for the removal of dyes in aqueous solutions with good recovery and recyclability.Graphical
Highlights
Several tons of commercial dye wastewaters are produced annually by a wide variety of industrial sources, such as printing, textiles and food processing [1,2,3]
The pure MCM-41 sample showed a set of five prominent peaks referring to a well-formed MCM-41 structure
Some variances could be noted comparing XRD spectra of pure MCM-41 and indium-doped samples; as a general trend, there is a broadening of the diffraction peaks accompanied by shifts to higher or lower 2theta degrees
Summary
Several tons of commercial dye wastewaters are produced annually by a wide variety of industrial sources, such as printing, textiles and food processing [1,2,3]. The release of such materials generates unpleasant colored water as the existence of less than 1 ppm of these dyes in water is highly perceptible. Biological and physical techniques such as coagulation, flocculation, membrane separation and adsorption have been progressively investigated to remove color and hazardous materials from contaminated water [6,7,8,9,10,11]. Abundant research has been dedicated to study dye’s adsorption mechanism and to search for a suitable adsorbent [12, 13]
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