Study of colloidal properties of natural and Al-pillared smectite and removal of copper ions from an aqueous solution

In this study, an Al-pillared smectite was synthesized and changes in its colloidal properties were investigated. The pillaring solution was prepared by mixing 0.4 mol L ⁻¹ NaOH and 0.2 mol L ⁻¹ AlCl ₃.6H ₂O solutions. Intercalated clays were heated to obtain the pillared clay, and X-ray diffractome...

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Bibliographic Details
Published in:Environmental technology 2015-03, Vol.36 (6), p.786-795
Main Authors: Sartor, Lucas Resmini, de Azevedo, Antonio Carlos, Andrade, Gabriel Ramatis Pugliese
Format: Article
Language:English
Subjects:
adsorbents
Adsorption
aluminum
Aluminum - chemistry
aqueous solutions
clay
colloidal properties
Colloids
copper
Copper - isolation & purification
desorption
environmental technology
fluorescence
Fourier transform infrared spectroscopy
heavy metal
mixing
montmorillonite
pillared clays
polyhydroxyaluminium
Porosity
Silicates - chemistry
smectite
sodium hydroxide
sorption isotherms
Spectrophotometry, Infrared
surface area
surface reactivity
Thermodynamics
Water Pollutants, Chemical - isolation & purification
X-radiation
X-Ray Diffraction
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Summary:In this study, an Al-pillared smectite was synthesized and changes in its colloidal properties were investigated. The pillaring solution was prepared by mixing 0.4 mol L ⁻¹ NaOH and 0.2 mol L ⁻¹ AlCl ₃.6H ₂O solutions. Intercalated clays were heated to obtain the pillared clay, and X-ray diffractometry (XRD), X-ray fluorescence (XRF), Fourier transform infrared (FTIR) spectroscopy and N ₂ sorption/desorption isotherms analysis were done to characterize the changes in clay properties. Moreover, adsorption experiments were carried out in order to evaluate the capacity of the pillared clays to remove Cu ²⁺ from an aqueous solution and to characterize the interaction between adsorbent and adsorbate. The results indicate that the natural clay has a basal spacing of 1.26 nm, whereas the pillared clays reached 1.78 nm (500°C) and 1.80 nm (350°C) after calcination. XRF analysis revealed an increase in the Al ³⁺ in the pillared clay as compared to the natural clay. The surface area and pore volume (micro and mesoporous) were higher for the pillared clays. Experimental data from the adsorption experiment were fit to Langmuir and Freundlich and Temkin adsorption models, and the former one was the best fit (highest r ² value) for all the clays and lower standard deviation (Δ g %) for the natural clay. On the other hand, the Temkin model exhibited Δ g % value lower for the pillared clays. Thermodynamics parameters demonstrate that the Cu ²⁺ adsorption process is spontaneous for all the clays, but with higher values for the pillared materials. In addition, application of the Dubinin–Radushkevich model revealed that the bond between the metal and the clay are weak, characterizing a physisorption.
ISSN:1479-487X
0959-3330
1479-487X
DOI:10.1080/09593330.2014.961564