Due to the serious threat of excessive copper and magnesium ions to human health, it is crucial to detect copper and magnesium ions in aquatic environments. In this study, we propose a colorimetric strategy – gold nanoparticles (AuNPs) modified by 5-(3-aminophenyl)-1H-tetrazole (TA@AuNPs) for the rapid and portable identification of copper and magnesium ions in water. As the concentration of the target metal ions increases, the colorimetric principle (TA@AuNPs) causes the aggregation of the AuNPs system, shifts of the surface plasma resonance (SPR) absorption peak, and a change of system colors (wine-red to gray-blue). The advantages of this work: 1) the detection process is simple without complex pretreatment; 2) the concentration of the target ions could be quickly detected within 3 min by Standard Color Cards; 3) it can selectively detect two kinds of metal ions (Cu 2+ and Mg 2+ ) with high specificity in the presence of other interfering ions; 4) It eliminates the interference of calcium ions in the detection of magnesium ions; 5) It has excellent linearity and low detection limit (for Cu 2+ : R 2 = 0.94, LOD = 30.0 μM by the naked eye and 0.229 μM through ultraviolet–visible spectroscopy; for Mg 2+ : R 2 = 0.96, LOD = 300 μM by the naked eye and 0.653 μM through ultraviolet–visible spectroscopy). Furthermore, the colorimetric mechanism of the present work has been comprehensively demonstrated through DLS, TEM, zeta potential analysis, FT-IR, UV–vis and Gaussian calculations.
Contamination with β-blockers such as propranolol (PRO) poses a potential threat to human health and ecological system. The present study investigated the kinetics and mechanisms of PRO degradation by UV-activated persulfate (UV/PS) oxidation. Here, the experimental results showed that the degradation of PRO followed pseudo-first-order reaction kinetics, the degradation rate constant ( k obs ) was increased dramatically with increasing PS dosage or decreasing initial PRO concentration. And increasing the initial solution pH could also enhance the degradation efficiency of PRO. Radical scavenging experiments demonstrated that the main radical species was sulfate radicals (SO 4 •− ), with hydroxyl radicals (HO·) playing a less important role. Meanwhile, the second-order rate constants of PRO degradation with SO 4 •− and HO· were determined to be 1.94 × 10 10 M −1 s −1 and 6.77 × 10 9 M −1 s −1 , respectively. In addition, the presence of natural organic matter (NOM) and nitrate anion (NO 3 − ) showed inhibitory effect on PRO degradation, whereas bicarbonate anion (HCO 3 − ) and chlorine anion (Cl − ) greatly enhanced the degradation of PRO. Moreover, the transformation products of PRO were identified by applying ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS) technique. Molecular orbital calculations were used to estimate the reaction site of PRO with radicals, simultaneously. Hence, the transformation pathways including hydroxylation, dehydration, naphthalene ring opening, and the cleavage of aldehyde groups were proposed. This work enriches the mechanism of PRO degradation under UV/PS system on the basis of results obtained by experimental characterization and Gaussian theoretical calculation.
Given the pressing need to treat wastewater contaminated with antibiotics, particularly ciprofloxacin (CIP), a novel 2D MXene/flower-like C-SnS 2 Schottky junction photocatalyst was developed for the CIP degradation using a peroxymonosulfate (PMS)-assisted photocatalytic system. Under visible light irradiation, the 10-MXene/C-SnS 2 /PMS system achieved a CIP degradation efficiency of 98.2 % (rate constant: 0.07068 min⁻¹) within 60 min, representing 5.51-fold and 4.52-fold enhancements compared to C-SnS 2 and MXene/C-SnS 2 , respectively. These results demonstrated the synergistic effect between photocatalysis and PMS activation, as well as the critical role of MXene in enhancing the reaction efficiency. Density functional theory (DFT) calculations, combined with experimental data, elucidated the catalytic reaction mechanism. Moreover, Gaussian calculations identified key degradation intermediates. This study provides new insights into the construction of Schottky heterojunction photocatalysts combined with PMS catalytic systems for the degradation of organic pollutants.
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