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Removal of pharmaceutically active compounds (PhACs) from real membrane bioreactor (MBR) effluents by photocatalytic degradation using composite Ag2O /P-25 photocatalyst
摘要： Pharmaceutically active compounds (PhACs) are emerging pollutants causing serious challenges to wastewater treatment plants due to poor biodegradability. In this study, the enhanced removal of highly recalcitrant and commonly monitored PhACs, carbamazepine (CBZ) and diclofenac (DCF) by heterogeneous photocatalysis was investigated using 5% Ag2O /P-25 photocatalyst. The photocatalyst was characterized by scanning electron microscope (SEM-EDX), Brunauer-Emmett-Teller (BET), and UV-vis diffuse reflectance spectra (UV-DRS). The effects of catalyst dose, initial pollutants concentration, and mineralization during the photocatalytic degradation of PhACs were investigated. The matrix effect was assessed in deionized water (DW) and real membrane bioreactor effluent (RME). Optimal CBZ and DCF removals of 89.10 % and 93.5 %, respectively for 180 min of UV irradiation were achieved at catalyst dosage of 0.4 g L-1 in DW matrix. However, the optimal catalyst dosages for CBZ and DCF in RME matrix were increased by factor 2 and 1.5, respectively, to achieve the same degree of removal. Declining trends of removal rate were observed when initial concentrations of both the PhACs were increased under optimal catalyst dosages, and kinetics seem to fit the Langmuir-Hinshelwood model. Photo-induced holes and ?OH were the dominant oxidation species involved in the photocatalytic degradation of the PhACs. A plausible reusability of 5% Ag2O /P-25 photocatalyst was observed for both the PhACs. Moreover, various aromatic/aliphatic intermediates generated during the photodegradation CBZ were identified using fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometry, and a possible multi-step degradation pathway was proposed. Overall, the removal of PhACs using 5% Ag2O /P-25 photocatalyst showed promising results in real wastewater.
关键词： PhACs,transformation products,Ag2O/P-25 photocatalysts,matrix effect,photocatalytic degradation
更新于2025-09-23 15:23:52
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Matrix effect impact on measuring hardness of metals bombarded by accelerated ions using laser induced breakdown spectroscopy
摘要： For safety reasons, the need of a fast in situ technique for measuring change in surface hardness of nuclear reactor vessel walls due to ion bombardment has great importance. Material hardness measurement using laser induced breakdown spectroscopy has been demonstrated as a new promising technique. The effect of the material matrix is one of the challenges that this technique for hardness measurement may face. In this work, the plasma excitation temperature Te has been used to measure the relative hardness of some pure Ti and Ti alloy samples with different hardnesses. The hardness of these samples was changed by irradiating the samples with 1 MeV carbon (C) ions with different doses. On studying the average crystallite size of these samples using x-ray diffraction and its relation with hardness, it was found that pure Ti samples and Ti alloys show different behaviors. On the other hand, it was found that although there is a good linear relation between Te and the Vickers hardness, the sample matrices have a strong influence on the measurements, especially for samples with small hardness value differences, irrespective of their average crystallite size.
关键词： titanium,matrix effect,hardness,LIBS
更新于2025-09-19 17:13:59
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Hydrogen isotopic analysis using molecular emission from laser-induced plasma on liquid and frozen water
摘要： The hydrogen isotopes in liquid and frozen water samples were analyzed by laser ablation molecular isotopic spectrometry (LAMIS), which employs the molecular emission from laser-induced plasma for isotope analysis. Molecular emission bands of OH and NH radicals were observed, and their spectral features were characterized in accordance with sample matrix and measurement conditions. The OH and NH bands exhibit different emission behavior, which was attributed to formation kinetics and thermodynamic factors. Under optimized condition, isotopic shift between hydrogenated (OH and NH) and deuterated (OD and ND) species was measured at individual rotational branches. By using these molecular bands, the partial least squares regression (PLSR) structure was established for quantitative analysis of hydrogen isotope and evaluated by cross-validation in terms of accuracy and precision. The PLSR result was good with root mean square error of prediction (RMSEP) of 0.3–0.7% for all species. Particularly, the case using OH/OD emission from liquid water revealed the most accurate result with RMSEP of 0.33%. It was affected by the quality and reproducibility of spectral data determined by utilized species. This study not only supports the behavioral understanding of molecular radicals in laser-induced plasma, but also identifies the feasibility of LAMIS for real-time application to quantitative analysis in various sample matrices.
关键词： Hydrogen isotope,LAMIS,Matrix effect,PLSR,Molecular emission band
更新于2025-09-12 10:27:22