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Particularities of trichloroethylene photocatalytic degradation over crystalline RbLaTa2O7 nanowire bundles grown by solid-state synthesis route
摘要： This is the first report on synthesis and photocatalytic activity for trichloroethylene (TCE) degradation under simulated solar light over RbLaTa2O7 layered perovskites with predominant nanowire or platelet morphologies. SEM images witnessed that the one step thermal treatment at 1200 °C lead to formation of RbLaTa2O7 nanowires with diameter of 80~320 nm and several microns in length associated in bundles and sharp-edged, merged platelets (minor phase). The two-step annealing at 950 °C and 1200 °C resulted in decrease of wires bundle population and increase in that of platelets merged in facetted particles. The RbLaTa2O7 nanowires are made of by well-aligned atomic rows with preferred orientation toward the c-axis, relatively free of defect. High density of hydroxyl groups on the sample calcined in mild conditions (RbLaTa_01) favors the photo mineralization of TCE. In contrast, the activity of RbLaTa_02 annealed in harsh conditions (950 and 1200 oC), poor in surface hydroxyl groups, remained modest. The weak surface basicity directed the reaction mainly to generation of intermediate chlorinated compounds. Pd and Au were supported on RbLaTa2O7 perovskites as an alternative strategy to boost the removal of chlorinated pollutants by combining photocatalytic (mineralization) and catalytic (hydrodechlorination, HDC) processes. The mineralization of TCE to Cl- was drastically hindered in presence of methanol due to quenching of ?OH radicals by alcohol. The results suggested that the density of RbLaTa2O7 surface hydroxyl groups is essential for photo mineralization of TCE whereas the surface carbonate is beneficial for the formation of intermediate chlorinated product.
关键词： solid state reaction,layered perovskites,trichloroethylene,simulated solar light,photocatalysis
更新于2025-09-23 15:21:21
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Treatment of Trichloroethylene with Photocatalyst-Coated Optical Fiber
摘要： In this present study, we investigated the effect of photocatalyzation on the degradation of trichloroethylene (TCE) in the aqueous phase by a photocatalyst-coated plastic optical fiber (POF). Two light-emitting diodes (LEDs) with low light intensity were used as the light source and TiO2 and ZnO were used as photocatalysts, which were characterized by scanning electron microscope (SEM) and UV-Vis diffuse reflectance spectroscopy (DRS). The para-chlorobenzoic acid (pCBA) was used as the hydroxyl radical probe for kinetic study and for the calculation of hydroxyl radical conversion rate (ROH,UV ). Experimental results show that POF coated with TiO2 exhibited higher degradation efficiency of TCE in basic solution, but POF coated with ZnO performed better in acidic solution. The increase of coating times resulted in the decrease in degradation efficiency of TCE due to increased thickness of the photocatalyst layer. The enhancement of light intensity contributed to the improvement of photocatalytic treatment efficiency. The ROH,UV for TiO2 and ZnO coated POF increased from 2 × 103 to 8 × 103 M s cm2 mJ?1 and from 8 × 102 to 2 × 103 M s cm2 mJ?1, respectively, as the pH increased from 4 to 10.
关键词： trichloroethylene (TCE),optical fiber,photocatalysis,groundwater,hydroxyl radical
更新于2025-09-12 10:27:22