Recovery of noble metal by photocatalytic reduction using layered TiO2 on mesoporous SiO2
Date Issued
2011
Date
2011
Author(s)
Liu, Hsuan-Hao
Abstract
The main purpose of this study is to enhance the metal adsorption efficiency by fabricating nTi/SBA-15 and nTi/KIT-6. A series of titania modified mesoporous silicate (SBA-15、KIT-6) samples with variable reflux times have been synthesized from Pluronic 123. The nano-materials were characterized by scanning electron microscopy/energy-dispersive X-ray spectrometer (SEM/EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), and nitrogen adsorption-desorption surface area analysis (BET). The BET surface area, pore diameter, and the pore volume of SBA-15 exhibits 751 m2/g, 6.80 nm, and 0.60 cm3/g.nm, respectively. Meanwhile KIT-6 exhibits 794 m2/g, 5.23 nm, and 1.04 cm3/g.nm. Different experimental conditions such as initial palladium concentration, reflux times of materials, pH value, and illumination time were controlled to analyze the kinetic of metal recovery by photodeposition with catalyst of monolayered TiO2 coating on mesoporous SiO2. The Pd separation rate of SBA-15, Ti/SBA-15, 2Ti/SBA-15 and 3Ti/SBA-15 were 0, 31.51, 48.37 and 13.42%. However KIT-6, Ti/KIT-6, 2Ti/KIT-6, 3Ti/KIT-6 were 0, 46.21, 55.52, 44.82%, respectively.
As we expected, monolayered TiO2 on mesoporous SiO2 performed well recovery ability of noble metal. The optimum operating values of material reflux times, initial palladium concentration, illumination time, and pH value for maximizing the recovery of noble metal have been determined to be twice(2Ti/SBA-15, 2Ti/KIT-6), 25-50 mg/L, 60 mins, 1-3. This research can apply on the increasing demands of noble metals, and maintain sustainable use in the future.
Subjects
mesoporous SiO2
photodeposition
noble metal
monolayered TiO2
recovery
Type
thesis
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