Formaldehyde, as a common pollutant in industrial exhaust gases, poses a serious threat to human health due to its highly toxic nature. Therefore, the development of efficient catalysts for formaldehyde removal is of great environmental significance. The accumulation of by-salts in the desulfurization waste stream of coking industry has become a major challenge in environmental protection. This paper used the by-salt ammonium thiocyanate as a precursor to prepare Cu-based g-C 3 N 4 (CN) by impregnation pyrolysis method, and applied it to the efficient catalytic oxidation of formaldehyde. The results showed that CN/Cu-10 %-a exhibited the best catalytic performance, with its specific surface area increasing 2.07 times compared to pure CN. The formaldehyde removal rate reached 98 %, which is 7.38 times higher than before modification, and it decreased by only 7.91 % after six cycles, demonstrating excellent cyclic stability. The improved photocatalytic performance is due to Cu doping, which increases the number of active sites, boosts visible light absorption, and facilitates the separation and transfer of photogenerated carriers. The secondary calcination further optimized the close contact between the metal Cu ions and the semiconductor interface, enhanced the specific surface area and the electron transfer efficiency to the metal Cu ions, and suppressed the charge carrier recombination. This study provides a new strategy and theoretical basis for the resourceful utilization of desulfurization waste liquid and the efficient degradation of formaldehyde.
Accurate and low-cost onsite assay of residual antibiotics in food and agriculture-related matrixes (e.g., milk) is of significant importance for evaluating and controlling food pollution risk. Herein, we employed hybrid Cu-doped-g-C 3 N 4 nanozyme to engineer smartphone-assisted onsite visual sensor for reliable and precise reporting the levels of tetracycline (TC) residues in milk through π-π stacking-triggered blocking effect. Benefiting from the synergetic effects of Cu 2+ and g-C 3 N 4 nanosheet, Cu-doped-g-C 3 N 4 nanocomposite exhibited an improved peroxidase-like activity, which could effectively catalyze H 2 O 2 to oxidate colorless TMB into steel-blue product oxTMB. Interestingly, owing to the blocking effect caused by the π-π stacking interaction between TC tetraphenyl skeleton and Cu-doped-g-C 3 N 4 nanozyme, the affinity of Cu-doped-g-C 3 N 4 nanocomposite toward the catalytic substrates was remarkably blocked, resulting in a TC concentration-dependent fading of solution color. Using smartphone-assisted detection a simple, low-cost, reliable, and sensitive portable colorimetric sensor-based nanozyme for onsite visual monitoring the residual TC in milk was successfully developed with a detection limit of 86.27 nM. Of particular mention is that this detection limit is comparable to most other reported colorimetric methods and below most official allowable residue thresholds in milk matrixes. This work gave a novel insight to integrate two-dimensional (2D) artificial nanozymes-based π-π stacking-triggered blocking effect with smartphone-assisted detection for developing efficient and low-cost colorimetric point-of-care testing of the risk factors in food and agriculture-related matrixes. Graphical abstract
A large variety of pharmaceuticals and personal care products (PPCPs) have been detected in water which makes it imperative to explore new materials for their efficient removal. In this study, the photo-Fenton degradation of pharmaceuticals has been investigated systematically via in situ synthesized Cu-doped g-C 3 N 4 . Detailed photoelectrochemical measurements confirm that the adsorption edges of modified g-C 3 N 4 show a remarkable shift (Band gaps decreased from 2.79 eV to 2.17 eV), indicating the advantages of solar light absorption . Three major reactive radicals were identified, including •OH, 1 O 2 , and - ∙O 2 . The sulfadimethoxine (SMT) was degraded completely (> 99 %) at a wide pH range from 4 to 8. A total of 16 micropollutants , including anti-inflammatory, quinolone, and macrolide, were spiked with low concentration (100 μg/L) in simulated water, which can be removed rapidly within only 3 min. To make separating and reusing easy, the powder was successfully loaded onto a PTFE (Poly tetra fluoroethylene) support (0.22 µm) with a loading amount of 1.29 mg/cm 2 . The pharmaceutical can be effectively degraded without obviously losing the active properties under simulated solar irradiation.
危险品化学品经营许可证（带存储）