Electronic Structure Optimization and Proton-Transfer Enhancement on Titanium Oxide-Supported Copper Nanoparticles for Enhanced Nitrogen Recycling from Nitrate-Contaminated Water.

Electrocatalytic reduction of nitrate to NH3 (NO3RR) on Cu offers sustainable NH3 production and nitrogen recycling from nitrate-contaminated water. However, Cu affords limited NO3RR activity owing to its unfavorable electronic state and the slow proton transfer on its surface, especially in neutral/alkaline media. Furthermore, although a synchronous "NO3RR and NH3 collection" system has been developed for nitrogen recycling from nitrate-laden water, no system is designed for natural water that generally contains low-concentration nitrate. Herein, we demonstrate that depositing Cu nanoparticles on a TiO2 support enables the formation of electron-deficient Cuδ+ species (0 < δ ≤ 2), which are more active than Cu0 in NO3RR. Furthermore, TiO2-Cu coupling induces local electric-field enhancement that intensifies water adsorption/dissociation at the interface, accelerating proton transfer for NO3RR on Cu. With the dual enhancements, TiO2-Cu delivers an NH3-N selectivity of 90.5%, mass activity of 41.4 mg-N h gCu-1, specific activity of 377.8 mg-N h-1 m-2, and minimal Cu leaching (<25.4 µg L-1) when treating 22.5 mg L-1 of NO3--N at -0.40 V, outperforming most of the reported Cu-based catalysts. A sequential NO3RR and NH3 collection system based on TiO2-Cu was then proposed, which could recycle nitrogen from nitrate-contaminated water under a wide concentration window of 22.5-112.5 mg L-1 at a rate of 209-630 mgN m-2 h-1. We also demonstrated this system could collect 83.9% of nitrogen from NO3--N (19.3 mg L-1) in natural lake water.

Near-infrared spectroscopy as a potential tool with radial basis function for measurement of residual acrylamide in organic polymer.

Poly(acrylamide-co-diallyldimethylammonium chloride) (PDA), which is usually prepared by free radical polymerization of acrylamide monomer (AM) onto the cationic monomer dimethyl diallyl ammonium chloride (DMDAAC), has been widely applied to wastewater treatment; however, the free-radical polymerization is always incomplete with residual AM remaining in the PDA. The residual AM affects the PDA's performance while also posing as a potential threat to human health; therefore, during preparation of the PDA, the rapid detection of the residual AM plays an important role in controlling the residual AM while improving the PDA's performance. The objective of this study was to explore the possibilities for applying near-infrared (NIR) spectroscopy as a potential tool for detecting the residual AM in combination with a statistical tool. In this study, the radial basis function (RBF) network model as the statistical tool was combined with NIR spectroscopy for detection of the residual AM. The experimental results showed that five wavelengths in the NIR spectroscopy were the most important characteristic adsorption peaks, particular at 971.95 and 1077 nm. The simulation of the RBF model presented higher performance with R2-value greater than 0.98, RMSEC and RMSEP less than 7.22 x 10(-5) and coefficient of variation (CV) of the predicted residual AM less than 10%, which demonstrated the feasibility of the NIR spectroscopy being a rapid detection tool for prediction of the residual AM using the RBF model. Wavelet de-nosing was used for removing the interference/noise in the NIR spectroscopy and improved the generalization ability of the RBF model.

Degradation of Bisphenol A by CeCu Oxide Catalyst in Catalytic Wet Peroxide Oxidation: Efficiency, Stability, and Mechanism.

The CeCu oxide catalyst CC450 was prepared by citric acid complex method and the catalytic wet peroxide oxidation (CWPO) reaction system was established with bisphenol A (BPA) as the target pollutant. By means of characterization, this research investigated the phase structure, surface morphology, reducibility, surface element composition, and valence of the catalyst before and after reuse. The effects of catalyst dosage and pH on the removal efficiency of BPA were also investigated. Five reuse experiments were carried out to investigate the reusability of the catalyst. In addition, this research delved into the changes of pH value, hydroxyl radical concentration, and ultraviolet-visible spectra of BPA in CWPO reaction system. The possible intermediate products were analyzed by gas chromatography-mass spectrometry (GC-MS). The catalytic mechanism and degradation pathway were also discussed. The results showed that after reaction of 65 min, the removal of BPA and total organic carbon (TOC) could reach 87.6% and 77.9%, respectively. The catalyst showed strong pH adaptability and had high removal efficiency of BPA in the range of pH 1.6-7.9. After five reuses, the removal of BPA remained above 86.7%, with the structure of the catalyst remaining stable to a large extent. With the reaction proceeding, the pH value of the reaction solution increased, the concentration of OH radicals decreased, and the ultraviolet-visible spectrum of BPA shifted to the short wavelength direction, that is, the blue shift direction. The catalysts degraded BPA rapidly in CWPO reaction system and the C-C bond or O-H bond in BPA could be destroyed in a very short time. Also, there may have been two main degradation paths of phenol and ketone.