In Situ Growth of Nitrogen-Doped Carbon Nanotubes Based on Hierarchical Ni@C Microspheres for High Efficiency Bisphenol A Removal through Peroxymonosulfate Activation

Abstract

N-doped carbon nanotubes (NCNTs) are promising metal-free heterogeneous catalysts toward peroxymonosulfate (PMS) activation in advanced oxidation processes for wastewater remediation. However, conventional CNTs always suffer from serious agglomeration and low N content, which renders their design synthesis as an important topic in the related field. With hierarchical Ni@C microspheres as a nutritious platform, we have successfully induced in situ growth of NCNTs on their surface by feeding melamine under high-temperature inert atmospheres. These as-grown NCNTs with a small diameter (ca. 20 nm) are firmly rooted in Ni@C microspheres and present loose accumulation on their surface, and their relative content can be tailored easily by manipulating the mass ratio of melamine to Ni@C microspheres. The investigation on bisphenol A (BPA) removal reveals that the loading amount of NCNTs affects the catalytic performance greatly, and the optimum ratio of melamine to Ni@C microspheres is 5.0 because the corresponding MNC-5.0 possesses sufficient surface N sites and moderate electron transfer, resulting in powerful PMS activation and sufficient utilization of reactive oxidative species (ROS). MNC-5.0 also addresses its advantages as compared with other NCNTs from post treatment and spontaneous growth strategies. The primary ROS responsible for BPA degradation are identified as hydroxyl radical, sulfate radical, superoxide radical, and singlet oxygen through quenching experiments and electron paramagnetic resonance, and the corresponding catalytic mechanism is also put forward based on these results.

MnO2 Nanosheet Nets on Carbon Fiber as Fixed Catalysts for a Highly Efficient, Nonradical Fenton-like Process in Wastewater Refractory Pollutant Treatment

“…X-ray diffraction (XRD) plots (Figure a) showed typical broad diffraction peaks at 25.8° and 42.9°, which can be indexed to the (002) and (101) planes of graphitic carbon of CF . No obvious diffraction peaks of MnO 2 were observed for 3D-MNSN-CF(5), which could be partially attributed to relatively low coating amount of MnO 2 and partially ascribed to the porous structure of CF sheets and round property of CF.…”

“…In the case of 3D-MNSN-CF (5), insufficient growth of the 3D nanosheet net resulted in uniform and dense nanosheets at the bottom, along with some irregular nanosheets on the surface (Figure S1a X-ray diffraction (XRD) plots (Figure 2a) showed typical broad diffraction peaks at 25.8°and 42.9°, which can be indexed to the (002) and (101) planes of graphitic carbon of CF. 32 No obvious diffraction peaks of MnO 2 were observed for 3D-MNSN-CF( 5), which could be partially attributed to relatively low coating amount of MnO 2 and partially ascribed to the porous structure of CF sheets and round property of CF. A typical diffraction peak at 12.3°corresponding to the (110) crystal plane of δ-MnO 2 was observed for the 3D-MNSN-CF(X) (X = 20, 40, and 50), 22 and the intensity was increased along with the increasing amount of KMnO 4 .…”

Bifunctional Solar Evaporator with Co/N-Doped Graphene Oxide for Synergistic Steam Generation and Organic Pollutant Degradation

“…To reveal the mechanism of SMX decomposition by the CNG-800/MF evaporator, a chemical quencher experiment and EPR analysis were conducted to recognize the working ROS involved in the SMX decomposition process. MeOH was commonly used to scavenge • OH/SO 4 •– , TBA was utilized to eliminate • OH, and p-BQ was added to quench O 2 •– . When MeOH, TBA, and p-BQ were put into the evaporation reaction system, the SMX degradation efficiencies decreased to 99.7, 99.8, and 72.4%, and the corresponding k values were 0.059, 0.086, and 0.020 min –1 , respectively.…”

“…•− . 52 When MeOH, TBA, and p-BQ were put into the evaporation reaction system, the SMX degradation efficiencies decreased to 99.7, 99.8, and 72.4%, and the corresponding k values were 0.059, 0.086, and 0.020 min −1 , respectively. Furfuryl •− and DMPO-• OH adducts with a 1:2:2:1 signal were observed, suggesting that the SO 4…”

Recent advances in metal-free catalysts for the remediation of antibiotics, antibiotic resistant bacteria (ARB), and antibiotic resistant genes (ARGs)

“…23–25 In recent decades, the metal-free catalyzed AOPs have caused a research upsurge due to their unique advantages, such as environmental friendliness, minimized operational cost, and flexible and adjustable running processes. 26–28 Nevertheless, although metal-free catalysts can avoid secondary pollution to a great extent, they usually suffer from inherent chemical inertness. Therefore, significant efforts have been made to improve the catalytic activity of metal-free catalysts through diverse modification methods.…”