Manli Guo

A magnetic CoFeAl-layered double hydroxide (LDH) material was synthesized via a hydrothermal method, followed by sulfidation treatment with sodium sulfide, and the obtained S/CoFeAl-LDH nanocomposite was used as a peroxymonosulfate (PMS) activator for efficient degradation of antibiotics in water by using norfloxacin (NOR) as a model. Through sulfidation modification, the proportion of low-valent metal ions in the composites was increased. Therefore, the S/CoFeAl-LDH displayed a higher performance of NOR degradation via the activation of PMS than the CoFeAl-LDH. Within 6 min, 0.10 g per L S/CoFeAl-LDH and 0.20 g per L PMS could degrade 98.3% NOR (20 mg L⁻¹). S/CoFeAl-LDH, as a heterogeneous catalyst, could efficiently activate PMS and degrade NOR in the pH range of 4–9. Since the synthesized material was a composite of magnetic CoFe₂O₄ and LDH, it could be recycled by magnetism after the reaction. After 4 cycles, the NOR degradation rate still reached 84.3%, indicating the good stability of the catalyst. During the degradation of NOR by S/CoFeAl-LDH/PMS, both free radical pathway and non-free radical pathway played a role, among which SO₄˙⁻, O₂˙⁻ and ¹O₂ were the main active species. The Co²⁺ and Fe²⁺ in the composites reacted with PMS to generate active species. The synergistic effect of metals and the reducibility of sulfur further promoted the cyclic regeneration of Co²⁺ and Fe²⁺, which was conducive to the activation of PMS to generate free radicals. In addition, the intermediate products of the degradation reaction were analyzed by LC-MS, and the possible degradation paths were put forward. This study revealed that the S/CoFeAl-LDH was a heterogeneous catalyst with good application prospect, which provides a new method for removing antibiotics from water.

Pharmaceuticals and personal care products (PPCPs) are currently drawing significant attention due to their environmental impact. Electro‐Fenton, one of the advanced oxidation processes (AOPs), is an efficient and comprehensive technology to degrade all kinds of organic pollutants, but the degradation efficiency relies on cathode material. In this work, phosphorus‐doped porous carbon material coated graphite felt (P‐GF) was prepared by adopting phytic acid as a phosphorus source through high temperature solid‐state method. The microstructure and the elements composition of this fabricated material were investigated by SEM, BET and XPS. With phosphorus doping and plenty of carbon porous structures, the hydrophilicity and infiltrating property of the P‐GF had been greatly improved. The prepared P‐GF material enhanced the electrochemical reduction of O₂ and could significantly enhance the yield of H₂O₂. It was used as a cathode to degrade pollutants under a constant potential, and methylparaben (MePa) was chosen as a research model for optimizing the experimental conditions and analyzing the possible degradation pathway. The P‐GF cathode achieved an excellent ability of degrading nearly 100 % of methylparaben within 3 h. The simultaneous removal ability of the P‐GF to four parabens was impressed. Additionally, the P‐GF material exhibited outstanding reusability.

In this work, nitrogen-doped magnetic porous carbon material (N-MPC) was prepared through the high-temperature calcination of low-cost [Fe(CN)₆]³⁻-loaded anion-exchange resin, which was experimentally demonstrated to have significant adsorption performance for tetracycline (TC) in water. The N-MPC adsorbent with a large specific surface area (781.1 m² g⁻¹) was able to maintain excellent performance in a wide pH range from 4 to 10 or in high ionic strength solution. The adsorption of TC on N-MPC was found to be more consistent with the pseudo-second-order model and Langmuir adsorption model, and the maximum adsorption capacity (q_{m, cal}) was calculated to be 603.4 mg g⁻¹. As a recoverable magnetic adsorbent, the N-MPC remained a TC removal rate higher than 70% after four adsorption cycles. The adsorption mechanism was speculated on the basis of characterizations, where pore filling, hydrogen bonding interaction, and π-π electron donor–acceptor (EDA) interaction were crucial adsorption mechanisms. A variety of antibiotics were selected for adsorption, and excellent performance was found especially for TCs, indicating that the N-MPC can be used for the efficient removal of TCs from water.

An ultrasensitive electrochemical sensing platform based on three-dimensional (3D) graphene-like carbon architecture (3D-HPG) and polythionine (PTH) modified glassy carbon electrode (GCE) was developed for the determination of metronidazole. The 3D-HPG/PTH interface possesses 3D porous structure, large electro-active surface area and excellent electrical conductivity. Electrochemical behavior of metronidazole at the 3D-HPG/PTH/GCE was investigated by cyclic voltammetry (CV), and it has been found that the 3D-HPG/PTH nanocomposite exhibited synergistic electro-catalytic property for the reduction of metronidazole. Under the optimized conditions, metronidazole was determined by CV and differential pulse voltammetry (DPV). DPV was found to be more effective for detecting low concentrations of metronidazole. Two linear ranges of 0.05−70 μM and 70−500 μM were obtained, with a detection limit of 1 nM (S/N = 3). The 3D-HPG/PTH/GCE exhibits high sensitivity, good selectivity, satisfactory reusability and reproducibility. It was applied for the determination of metronidazole in real water samples, with satisfactory recoveries ranging from 92.8% to 103%, and was successfully applied for the analysis of pharmaceutical dosage form.

A novel, sensitive, nonenzymatic amperometric sensor for the reliable detection of extracellular H₂O₂ released from living cells was fabricated based on Fe₃O₄/reduced graphene oxide (Fe₃O₄/rGO) nanocomposites, which were prepared using a simple and cost-effective one-pot approach. Electrochemical performances of the Fe₃O₄/rGO nanocomposites modified glassy carbon electrode (GCE) were studied. The results demonstrated that this H₂O₂ sensor exhibited excellent electrocatalytic performance towards the reduction of H₂O₂ at a potential of −0.3 V in the wide linear concentration range from 0.001 to 20 mM with a high sensitivity of 387.6 μA mM⁻¹ cm⁻² and a detection limit as low as 0.17 μM (S/N = 3), which was lower than certain enzymes and noble metal nanomaterials-based biosensors. Moreover, good anti-interference property, reproducibility, and long-term stability of the enzymeless sensor were achieved. Because of these remarkable analytical advantages, a novel, effective approach for the detection of extracellular H₂O₂ released from HeLa cells stimulated by CdTe quantum dots (QDs) was established by the constructed sensor. Since H₂O₂ is a byproduct of several oxidative biological reactions, this work could be applied to study the downstream biological effects of various stimuli in pathophysiology, and may expand the application of Fe₃O₄-based nanomaterials in the field of electrochemical sensing and bioanalysis.