Highly efficient activation of peroxymonosulfate by ZIF-67 anchored cotton derived for ciprofloxacin degradation.

Metal-organic framework (MOF) and MOF-derived materials have attracted extensive research interest as environmental catalysts. In this study, a composite material (ZIF-67/CCot-8) was successfully prepared using cotton fiber as a substrate and growing ZIF-67 in situ. This material exhibited excellent catalytic performance and significantly improved the efficiency of antibiotics degradation. ZIF-67/CCot-8 at a concentration of 0.05 g/L, combined with 0.2 mM peroxymonosulfate (PMS), removed approximately 97% of ciprofloxacin (CIP) and 99% of tetracycline and sulfamethoxazole within 15 min. The high catalytic efficiency of this catalyst is mainly attributed to the uniform distribution of ZIF-67-derived nanoparticles on the surface of the cotton fibers, providing abundant active sites and thereby significantly enhancing the efficiency of antibiotics degradation. Radical quenching experiments and electron paramagnetic resonance (EPR) analyses revealed that sulfate radicals (SO4•-) and singlet oxygen (1O2) were the main active species. Mass spectrometry (MS) was used to elucidate the CIP degradation pathway. The growth of the roots and stems of soybean sprouts in different water environments (tap water, treated water, and untreated water) was also observed. The results demonstrated a significant improvement in the inhibition of plant growth in the post-degradation CIP solution, indicating a substantial reduction in the toxicity of the degraded aqueous solution. To validate the practicality of the ZIF-67/CCot-8/PMS system, a continuous-flow water-treatment device was designed. This system removed 98% of the CIP solution within 180 min, demonstrating its excellent durability. This study presents a potential pathway for effective antibiotics removal using MOF-derived materials.

Enhanced peroxymonosulfate activation over heterogeneous catalyst Cu0.76Co2.24O4/SBA-15 for efficient degradation of sulfapyridine antibiotic.

The largest source of resistant bacteria or viruses is the overuse and misuse of antibiotics in humans and animals. These resistant bacteria or viruses may evolve into superbacteria or superviruses, which causes global plague. Therefore, it is significant to find a highly efficiency and low-cost method to eliminate antibiotics in water environment from inappropriate discharge. Here, a highly active and highly stable heterogeneous catalyst, Cu0.76Co2.24O4/SBA-15 (CCS) was prepared for peroxymonosulfate (PMS) activation in aim of decomposing persistent sulfapyridine (SPD). The reaction mechanism was thoroughly investigated via in situ quenching test and in situ electron paramagnetic resonance. Four reactive species, SO4·-, O2·-, 1O2 and ·OH were generated in Cu0.76Co2.24O4/SBA-15/PMS (CCSP) system. The SO4·- and O2·- were dominant active species responsible for SPD degradation. Co(Ⅱ)↔Co(Ⅲ)↔Co(Ⅱ) redox reaction cycle was constructed due to the different redox potential of Co(Ⅱ)/Co(Ⅲ), HSO5-/SO4∙-, and HSO5-/SO5∙-. Interestingly, Cu(Ⅰ) could urge the redox reaction cycle for PMS activation to be more thermodynamically feasible. Therefore, CCS possessed a highly catalytic activity and excellent stability. Meanwhile, the anions interference test indicated Cl-, NO3-, HCO3-, and H2PO4- had almost no inhibitory effect on SPD degradation over this catalytic system. We sincerely expected that this catalyst system would be applied extensively into antibiotics degradation in real water bodies.

Electrochemically-deposited PANI on iron mesh-based metal-organic framework with enhanced visible-light response towards elimination of thiamphenicol and E. coli.

Metal-organic frameworks (MOFs) are emerging class of porous materials that attracted tremendous attention as eco-friendly photocatalysts. However, poor charge separation in most MOFs largely thwarts their photocatalytic performance. In this work, Materials of Institut Lavoisier-100(Fe) (MIL-100 (Fe)) based on iron mesh was successfully fabricated by in situ growth. MIL-100(Fe) doped with polyaniline, namely MIL-100(Fe)/PANI, were then fabricated by galvanostatic deposition followed by annealing. Compared to pure MIL-100(Fe), MIL-100(Fe)/PANI composites exhibited excellent photocatalytic performances towards Thiamphenicol (TAP) degradation and Escherichia coli (E. Coli.) inactivation. The apparent rate constant, k, for TAP elimination of the MIL-100(Fe)/PANI composites with H2O2 is approximately 3 times as high as that of pure MIL-100(Fe). The electrochemical studies showed enhanced photocatalytic performances, which can be attributed to the electronic conductivity of PANI polymers. Quenching experiments, fluorescent tests and electron paramagnetic resonance (EPR) all suggested ⋅O2-, e-, ⋅OH and h+ as reactive oxidizing species (ROSs) involved in the photocatalytic process, where ⋅OH played the predominant ROSs. The transformation products of TAP were also isolated and characterized by high-resolution mass spectrometry, and transformation pathways of TAP under Vis/MIL-100(Fe)/PANI/H2O2 were tentatively clarified based on involved intermediates. Herein, MOFs conjugated conductive polymers nanocomposites look promising as efficient photocatalysts for organic pollutants degradation and bacteria inactivation. This work could offer novel strategies for the development of heterojunction composites with enhanced photocatalytic performances for better environmental remediation.

Oxidation of propyl paraben by ferrate(VI): Kinetics, products, and toxicity assessment.

Propyl paraben (propyl 4-hydroxybenzoate, PPB), one of the typically used paraben species in various pharmaceutical and personal care products, has been found in different aquatic environment, which could affect the water quality and human health. In this paper, the degradation of PPB by aqueous ferrate (Fe(VI)) was investigated in different water matrix and reaction kinetics as a function of pH was determined. Intermediate products of the degradation process were isolated and characterized by the high performance liquid chromatography/mass spectrometry/mass spectrometry techniques. Acute and chronic toxicities during water treatment of PPB using Fe(VI) were calculated using the ECOSAR program at three trophic levels. The obtained apparent second-order rate constant (kapp) for PPB reaction with Fe(VI) ranged from 99.6 ± 0.4 M-1 s-1 to 15.0 ± 0.1 M-1 s-1 with the half-life (t1/2) ranging from 154 s to 1026 s at pH 6.5-10.0 for an Fe(VI) concentration of 600 µM. The proposed pathway for the oxidation of PPB by Fe(VI) involves one electron transfer of phenoxyl radical and breaking of the ether bond. In general, the oxidation of PPB by ferrate resulted in a significant decrease in toxicity at three trophic levels.

Advanced oxidation kinetics and mechanism of preservative propylparaben degradation in aqueous suspension of TiO2 and risk assessment of its degradation products.

The absolute kinetic rate constants of propylparaben (PPB) in water with different free radicals were investigated, and it was found that both hydroxyl radicals (HO(•)) and hydrated electrons could rapidly react with PPB. The advanced oxidation kinetics and mechanisms of PPB were investigated using photocatalytic process as a model technology, and the degradation was found to be a pseudo-first-order model. Oxidative species, particularly HO(•), were the most important reactive oxygen species mediating photocatalytic degradation of PPB, and PPB degradation was found to be significantly affected by pH because it was controlled by the radical reaction mechanism and was postulated to occur primarily via HO(•)-addition or H-abstraction reactions on the basis of pulse radiolysis measurements and observed reaction products. To investigate potential risk of PPB to humans and aqueous organisms, the estrogenic assays and bioassays were performed using 100 µM PPB solution degraded by photocatalysis at specific intervals. The estrogenic activity decreased as PPB was degraded, while the acute toxicity at three trophic levels first increased slowly and then decreased rapidly as the total organic carbon decreased during photocatalytic degradation.

Indirect photochemical transformations of acyclovir and penciclovir in aquatic environments increase ecological risk.

Acyclovir and penciclovir, 2 antiviral drugs, are increasingly detected in aquatic environments. The present study explores the natural photochemical transformation mechanisms and fate of these drugs, examining direct and indirect photochemical transformation under simulated sunlight irradiation. The 2 antiviral drugs are photostable under certain conditions but significantly degrade in the presence of chromophoric dissolved organic matter (DOM). The degradation rate associated with the drugs' indirect photochemical transformation scaled with chromophoric DOM concentration. Quenchers and sensitizers were used to identify indirect photochemical transformation mechanism. Results suggested that both pharmaceuticals could be transformed by reacting with (1)O2, (•)OH, and excited chromophoric DOM. The (1)O2 played an important role in indirect photochemical transformation. Furthermore, the reaction kinetics between their substructural molecules, guanine, isocytosine, and imidazole, with different reactive oxygen species were evaluated to determine which substrate functionalities were most susceptible to singlet oxygenation. Imidazole was identified as the reaction site for (1)O2, and preliminary (1)O2 oxidation mechanisms were further evaluated based on liquid chromatographic-tandem mass spectrometric results. Finally, aquatic ecotoxicity assessment of phototransformed solutions revealed that the degradation of acyclovir and penciclovir may not ultimately diminish environmental risk because of either formation of more toxic intermediates than parent pharmaceuticals or some synergistic effects existing between the intermediates.

Photocatalytic degradation kinetics and mechanism of antivirus drug-lamivudine in TiO2 dispersion.

Photocatalytic degradation kinetics of antivirus drug-lamivudine in aqueous TiO(2) dispersions was systematically optimized by both single-variable-at-a-time and central composite design based on the response surface methodology. Three variables, TiO(2) content, initial pH and lamivudine concentration, were selected to determine the dependence of degradation efficiencies of lamivudine on independent variables. Response surface methodology modeling results indicated that degradation efficiencies of lamivudine were highly affected by TiO(2) content and initial lamivudine concentration. The highest degradation efficiency was achieved at suitable amount of TiO(2) and with maintaining initial lamivudine concentration to a minimum. In addition, the contribution experiments of various primary reactive species produced during the photocatalysis were investigated with the addition of different scavengers and found that hydroxyl radicals was the major reactive species involved in lamivudine degradation in aqueous TiO(2). Six degradation intermediates were identified using HPLC/MS/MS, and photocatalytic degradation mechanism of lamivudine was proposed by utilizing collective information from both experimental results of HPLC/MS/MS, ion chromatography as well as total organic carbon and theoretical data of frontier electron densities and point charges.