Stirring-ageing technique to develop zirconium-pillared bentonite clay along with its surface profiling using various spectroscopic techniques
The pillared clays are getting wide attention due to the easiness in tailoring their surface for customized applications. In our laboratory, we have adopted a novel synthetic route to pillar zirconium species within intercalation spaces of bentonite clay through stirring-ageing technique and prepared the zirconium-pillared bentonite clay (ZPBC). A series of experiments conducted to optimize the stirring-ageing time span revealed that 2–4 h span is sufficient for getting a good yield of ZPBC. The synthesized ZPBC was characterized using certain well-developed sophisticated techniques to obtain their physical, structural and morphological properties. The high surface area 109 m2 g−1 noticed for ZPBC is suitable in retaining the chemical moieties of special interest during pollutant removal processes. X-ray fluorescence studies revealed that there is an increase in wt% of Zr (4.76%) in pillared clay compared to Na-bentonite which indicates that Zr has been successfully loaded on the surface of parent clay during pillarization. The mineralogical composition and the gradual changes in the interlayer spacing of parent and pillared clay are well established using X-ray diffraction technique. The Raman spectrum identifies changes in the lattice vibration modes of ZPBC as pillaring takes place. The surface topographical changes that occurred in clay after modification were revealed from the scanning electron microscopy images. The prepared ZPBC were tested successfully for the removal of phosphate from aqueous solution and obtained a maximum adsorption capacity 58.83 mg g−1 at 30 °C.
KeywordsZirconium pillaring X-ray fluorescence Raman spectroscopy Bentonite clay Phosphate adsorption
We are thankful to Dr. N. Purnachandra Rao, Director, NCESS, for providing laboratory and knowledge resource facilities. The instrumental facilities in NCESS under SWQM (Sea Water Quality Monitoring) programme funded by ICMAM, Ministry of Earth Sciences and Central Chemical Laboratory (CCL), is also acknowledged. The Raman spectra provided by the Geo Fluids Research Laboratory (GFRL) in NCESS is highly appreciated. The authors are also thankful to the X-RF, X-RD and SEM–EDS laboratories in NCESS for providing the respective spectral data. The particle size and surface area analysis was carried out in Particle Size Analysis Laboratory, NCESS, and their service is also acknowledged.
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