Wenying Lv

Quantifying interactions between propranolol and dissolved organic matter (DOM) from different sources using fluorescence spectroscopy

Beta blockers are widely used pharmaceuticals that have been detected in the environment. Interactions between beta blockers and dissolved organic matter (DOM) may mutually alter their environmental behaviors. To assess this potential, propranolol (PRO) was used as a model beta blocker to quantify the complexation with DOM from different sources using the fluorescence quenching titration method. The sources of studied DOM samples were identified by excitation–emission matrix spectroscopy (EEMs) combined with fluorescence regional integration analysis. The results show that PRO intrinsic fluorescence was statically quenched by DOM addition. The resulting binding constants (log Koc) ranged from 3.90 to 5.20, with the surface-water-filtered DOM samples claiming the lower log Koc and HA having the highest log Koc. Log Koc is negatively correlated with the fluorescence index, biological index, and the percent fluorescence response (Pi,n) of protein-like region (PI,n) and the Pi,n of microbial byproduct-like region (PII,n) of DOM EEMs, while it is correlated positively with humification index and the Pi,n of UVC humic-like region (PIII,n). These results indicate that DOM samples from allochthonous materials rich in aromatic and humic-like components would strongly bind PRO in aquatic systems, and autochthonous DOM containing high protein-like components would bind PRO more weakly.

Decoration of TiO2/g-C3N4 Z-scheme by carbon dots as a novel photocatalyst with improved visible-light photocatalytic performance for the degradation of enrofloxacin

A novel visible-light-driven carbon dot (CDs)/TiO2/g-C3N4 photocatalyst was successfully synthesized by doping CDs in TiO2 nanoparticles and the surface of g-C3N4 nanosheets via a facile hydrothermal process and was confirmed by characterization methods. UV-vis diffuse reflectance spectra (DRS) revealed that CDs/TiO2/g-C3N4 showed obvious additional absorption in the 370–450 nm region. DMPO spin-trapping ESR spectra demonstrated the existence of O2˙− and ·OH. The photocatalytic activity of the CDs (1.0 wt%)/TiO2/g-C3N4 was remarkably enhanced as compared to that of the single components (TiO2 and g-C3N4) and double component (TiO2/g-C3N4) towards the degradation of enrofloxacin (ENX) under visible-light irradiation. About 91.6% of ENX was decomposed by CDs (1.0 wt%)/TiO2/g-C3N4 in 1 h, which is nearly 3.95 times, 4.82 times, and 1.69 times that for TiO2, g-C3N4, and TiO2 (90.0 wt%)/g-C3N4, respectively. Scavenging experiments revealed that O2˙− and ·OH played key roles during the photocatalytic degradation of ENX. This study provides a simple and convenient method to modify materials with enhanced photocatalytic performance, and the CDs/TiO2/g-C3N4 catalyst is efficient, stable, and reusable for environmental practical applications.

A novel spectrophotometric method for the determination of aminophylline with boric acid in pharmaceutical and mixed serum samples

This paper firstly describes a novel method to determine aminophylline (Ami) with boric acid (BA) by spectrophotometry. The study indicates that at pH 12.00 the absorbance of Ami decreases when BA is added. A simple, rapid, sensitive and reliable novel method based on the product of Ami and BA is obtained. Beers law is obeyed in the range of Ami concentrations of 0.20-200 microg ml(-1). The equation of linear regression is A=-2.57309x10(-4)-0.00355C (microg ml(-1)), with a linear correlation coefficient of 0.9969 and RSD 0.28%. The method is successfully applied to the determination of Ami in pharmaceutical samples and mixed serum samples, and average recoveries were in the range of 97.1-105.9%.

A sulfate radical based ferrous–peroxydisulfate oxidative system for indomethacin degradation in aqueous solutions

The degradation of indomethacin (IM) by ferrous ion-activated potassium peroxydisulfate (Fe2+/PDS) was investigated. We aimed to determine the optimal conditions for the removal of IM under different concentrations of Fe2+and PDS, evaluate the effects of operational parameters (solution pH, humic acid (HA), N2 bubbling and persulfate species), and propose the degradation mechanism of IM by the Fe2+/PDS system. The sequential addition of Fe2+ led to an improvement in the IM degradation and TOC removal efficiency. When the molar ratio of IM/PDS/Fe2+ was 1 : 1.5 : 2, the IM was almost completely degraded. Restrictions to the degradation efficiency of IM were caused by increasing the solution pH, bubbling with nitrogen, or through the addition of HA. A low concentration of Cl− had no effect on the reaction, while a high concentration led to a dramatic inhibitory effect. In addition, quenching experiments revealed that SO4˙− was the major active radical for the degradation of IM by ferrous ion-activated peroxydisulfate. Based on the identification of transformation products by liquid chromatography-mass spectrometry (LC-MS/MS), the pathways of the ferrous–peroxydisulfate oxidative system for the degradation of IM were tentatively proposed.

Impact of Humin on Soil Adsorption and Remediation of Cd(II), Pb(II), and Cu(II)

ABSTRACT In situ immobilization constitutes a promising technology for the mitigation of contaminants, through the reduction of metal bioavailability and mobility. This study investigated the adsorption isotherms and kinetic characteristics of humin extracted from peat soils. We also studied the influences of the pH, ionic strengths, and soluble organic matter concentrations of soil solutions on the adsorptive properties of humin, and compared its ability to detoxify potentially toxic metals in both actual and simulated soil solutions. The study results indicated that humin contains a massive population of oxygen-containing functional groups. Its adsorption capacity for Pb(II) was greater than that for Cu(II), which exceeded that for Cd(II). The adsorption of humin for Pb(II) conformed to the Freundlich model, while the adsorption of humin for Cd(II) and Cu(II) followed the Langmuir model. The adsorption kinetics of humin with respect to potentially toxic metals aligned well with second-order kinetics equations. As the pH was elevated, the potentially toxic metal adsorption by humin increased rapidly. Electrolyte ions and tartaric acids in solution both inhibited the adsorption of potentially toxic metals by humin, and its ability to inactivate potentially toxic metals. This was shown to be improved in actual field soil solutions in contrast to simulated soil solutions.

Insights into the synergetic mechanism of a combined vis-RGO/TiO2/peroxodisulfate system for the degradation of PPCPs: Kinetics, environmental factors and products

In recent years, how to effectively remove emerging organic pollutants in water bodies has been studied extensively, especially in the actual complex water environment. In the present study, an effective wastewater treatment system that combined photocatalysis and an oxidizing agent was investigated. Specifically, visible-light driven reduced graphene oxide (RGO)/TiO2 composites were prepared, and peroxodisulfate (PDS) was used as electron acceptor to accelerate the photocatalytic activity of this material. The vis-RGO/TiO2/PDS system exhibited outstanding properties in the degradation of diclofenac (DCF), which was also facilitated by acidic conditions and Cl-. Lake water, tap water, river water and HCO3- decreased the DCF degradation rate, while NO3- affected the system only slightly. Low concentrations of fulvic acid (FA) promoted the degradation of DCF via the generation of excited states, whereas a high concentration of FA inhibited the degradation, which was likely due to the light screening effect. The photocatalytic mechanism revealed that PDS served as an electron acceptor for the promotion of electron-hole pair separation and the generation of additional reactive oxygen species, while the RGO served as an electric conductor. The active substances, h+, OH, 1O2, SO4- and O2- were generated in this system, O2- and h+ played significant roles in the degradation of DCF based electron spin resonance tests and radical quenching results. According to the mass spectrometry results, the amide bond cleavage, dechlorination reaction, hydroxyl addition reaction, and decarboxylation reaction were the primary transformative pathways.

Sulfate radical-induced transformation of trimethoprim with CuFe2O4/MWCNTs as a heterogeneous catalyst of peroxymonosulfate: mechanisms and reaction pathways

Trimethoprim (TMP), a typical antibiotic pharmaceutical, has received extensive attention due to its potential biotoxicity. In this study, CuFe2O4, which was used to decorate MWCNTs via a sol–gel combustion synthesis method, was introduced to generate powerful radicals from peroxymonosulfate (PMS) for TMP degradation in an aqueous solution. The results showed that almost 90% of TMP was degraded within 24 min with the addition of 0.6 mM PMS and 0.2 g L−1 CuFe2O4/MWCNTs. The degradation rate was enhanced with the increase in initial PMS doses, catalyst loading and pH. A fairly low leaching of Cu and Fe was observed during the reaction, indicating the high potential recyclability and stability of CuFe2O4/MWCNTs. Electron paramagnetic resonance analysis confirmed that the CuFe2O4/MWCNT-PMS system had the capacity to generate ·OH and SO4˙−, whereas quenching experiments further confirmed that the catalytic reaction was dominated by SO4˙−. A total of 11 intermediate products of TMP was detected via mass spectrometry, and different transformation pathways were further proposed. Overall, this study showed a systematic evaluation regarding the degradation process of TMP by the CuFe2O4/MWCNT-PMS system.

Thermo-activated peroxydisulfate oxidation of indomethacin: Kinetics study and influences of co-existing substances

The widespread occurrence of non-steroidal anti-inflammatory drugs (NSAIDs) (e.g., Indomethacin) in the ambient environment has attracted growing concerns due to their potential threats to ecosystems and human health. Herein, we investigated the degradation of indomethacin (IM) by thermo-activated peroxydisulfate (PDS). The pseudo first-order rate constant (kobs) of degradation of IM was increased significantly with higher temperatures and PDS doses. Moreover, when the initial pH value was raised from 5 to 9 the IM degradation was initially decreased and then increased. Basic conditions were favorable for the removal of IM in the thermo-activated peroxydisulfate system. A response surface methodology based on the Box-Behnken design (BBD) was successfully employed for the optimization of the thermo-activated peroxydisulfate (PDS) system. The presence of chlorine ions manifested a dual effect on the degradation of IM, while bicarbonate and SRFA (as a NOM model) reduced it. Radical scavenging tests and electron spin resonance (ESR) revealed that the dominant oxidizing species were SO4- and OH at pH 9. Furthermore, the TOC removal efficiency attained 28.8% and the release of Cl-was 38.5% at 60 °C within 24min, while the mineralization rate of IM were 85.5% with the PDS concentration up to 20  mM at 2 h oxidation. To summarize, thermo-activated PDS oxidation is a promising technique for the remediation of IM-contaminated water.

The Dechlorination of 2,4-Dichlorophenol by Zero-Valent Iron

During the dechlorination of 2,4-dechlorophenol(2,4-DCP) by zero-valent iron(ZVI), pH was one of the important factors affecting the dechlorination. The adsorption of chlorophenol by ZVI and the dechlorination rate were influenced by pH. The dechlorination of 2,4-DCP by ZVI was pseudo-first-order reaction, the pseudo-first-order reaction rate constant (ΚSA) were respectively 0.1773 h-1, 0.2943 h-1, 0.062 h-1and 0.0525h-1 when pH were 2.5, 4.2, 5.8, and 10.0 . According to GC/MS, it was concluded that the process of 2,4-DCPs dechlorination via ZVI was: 2，4-DCP → 2-CP or 4-CP → phenol. The mechanism of dechlorination of 2,4-DCP by ZVI could be direct reduction on the surface of iron or reduction by atomic hydrogen or the conjunct action of them.