Catalytic Activation Of Persulfate Research Articles

Catalytic activation of persulfate by nanoscale zero-valent iron-derived supported boron-doped porous carbon for bisphenol A degradation.

In this study, boron-doped porous carbon materials (BCs) with high surface areas were synthesized employing coffee grounds as carbon source and sodium bicarbonate and boric acid as precursors; afterward, nanoscale zero-valent iron (nZVI) and BCs composites (denoted as nZVI@BCs) were further prepared through reduction of FeSO4 by NaBH4 along with stirring. The performance of the nZVI@BCs for activating persulfate (PS) was evaluated for the degradation of bisphenol A (BPA). In comparison with nZVI@Cs/PS, nZVI@BCs/PS could greatly promote the degradation and mineralization of BPA via both radical and non-radical pathways. On the one hand, electron spin resonance and radical quenching studies represented that •OH, SO4•-, and O2•- were mainly produced in the nZVI@BCs/PS system for BPA degradation. On the other hand, the open circuit voltages of nZVI@BCs and nZVI@Cs in different systems indicated that non-radical pathway still existed in our system. PS could grab the unstable unpaired electron on nZVI@BCs to form a carbon material surface-confined complex ([nZVI@BCs]*) with a high redox potential, then accelerate BPA removal efficiency via direct electron transfer. Furthermore, the performances and mechanisms for BPA degradation were examined by PS activation with nZVI@BC composites at various conditions including dosages of nZVI@BCs, BPA and PS, initially pH value, temperature, common anions, and humid acid. Therefore, this study provides a novel insight for development of high-performance carbon catalysts toward environmental remediation.

Catalytic activation of persulfate by 3D Cd(II) coordination polymers based on a flexible cyclotriphosphazene-functionalized ligand

Dye removal in wastewater can be done by catalytic reaction with coordination polymers. Herein, Two 3D Cd(II) coordination polymers, namely, {[Cd3(L)(H2O)4].(H2O)(DMF)}n (GTU-1) and {[Cd3(L)(4,4-bpy))(H2O)2].(H2O)}n (GTU-2), were prepared with a novel hexapod-shaped molecular building block, hexakis(methyl-2-(4-phenoxyphenyl)acetatebenzene) cyclotriphosphazene (H6L), by solvothermal reactions in dimethylformamide with nitric acid as the modulator. Cd(II) coordination polymers were characterized by Fourier transform infrared spectroscopy, thermal analysis, scanning electron microscopy, powder X-ray diffraction analysis and single crystal X-ray diffraction technique. GTU-1 represents a 3D pillared-layered coordination polymer structure containing 2D Cd-carboxylate (Cd(COO)n)-based inorganic building unit (IBU) whereas GTU-2 is a 3D coordination polymer derived from 1D IBU bridged together by deprotonated L6- and judiciously chosen ancillary linker 4,4-bipyridine (4,4-bpy). In both complexes, the flexible multisite cyclotriphosphazene bridging ligand (H6L) is completely deprotonated. GTU-2 exhibited relatively good catalytic activity towards rhodamine B (RhB), Methylen Blue (MB) and Acid Red 17 (AR-17) removal in aqueous solution.

Catalytic activation of persulfate by mechanically-treated natural pyrite: Revisit on the dominant role of sulfur vacancies and size effect

Mechanical treatment has been widely used to modify the surface properties of nature pyrite minerals and improve their catalytic performances; however, the mechanistic relationship still keeps unclear. In this study, we have systematically investigated the effect of milling speed treatment on the surface characteristics of commercial natural pyrite and evaluated the activation ability of persulfate (PDS) for the degradation of sulfamethoxazole (SMX). The results demonstrated that increase in the milling speed of 200–600 rpm could dramatically enhance the degradation and mineralization of SMX, while lower speed (≤200 rpm) exhibited marginal effect. The high milling speeds could reduce the content of sulfate and S(-II) in the pyrite and lead to the occurrence of sulfur vacancies (SVs) for promotional activation of PDS. Nevertheless, the SVs content was not in accordance with increased speed and size effect would mainly contribute to the efficient degradation of SMX. The milling pyrite/PDS system could efficiently treat a molasses-processed wastewater with COD removal of 770 mg/L, suggesting slow-release function of pretreated pyrite and it broaden application potential. In addition, based on the novel conclusion of the mechanism, this study provided a green, efficient and economical pyrite mechanical activation method and its application.

Catalytic Activation of Persulfate by Mechanically-Treated Natural Pyrite: Revisit on the Dominant Role of Sulfur Vacancies and Size Effect

Catalytic Activation of Persulfate by Mechanically-Treated Natural Pyrite: Revisit on the Dominant Role of Sulfur Vacancies and Size Effect

High performance of the A-Mn2O3 nanocatalyst for persulfate activation: Degradation process of organic contaminants via singlet oxygen

In this study, the catalytic activation of persulfate (PS) via metal oxides was investigated, and the A-Mn2O3 nanocatalyst was found to have the highest efficiency among other PS activators for the degradation of organic contaminants. Additionally, A-Mn2O3 exhibited a remarkable efficiency in activating PS for the degradation of phenol compared to both B-Mn2O3 and C-Mn2O3. This was attributed to the longer bonds between edge-sharing MnO6 octahedra, the unique structure, the high content surface –OH groups, and the average oxidation states. This indicated that all these properties played an important role in an efficient PS activation. Electron paramagnetic resonance (EPR) spectroscopy, scavenger tests, and chemical probes were conducted to investigate the reactive oxygen species (ROS). Singlet oxygen (1O2) was determined to be the main ROS generated from PS activation. A plausible mechanism study was proposed, which involved inner-sphere interactions. An electron transfer of the Mn species facilitated the decomposition of PS to generate HO2•/O2• − radicals, which were utilized as a precursor for 1O2 generation via direct oxidation or the recombination of HO2•/O2• −. Finally, the phenol and Sulfachloropyridazine (SCP) degradation pathways were proposed by 1O2 over the A-Mn2O3/PS system according to HPLC and LC-MS results.

Catalytic degradation of tetracycline hydrochloride by persulfate activated with nano Fe0 immobilized mesoporous carbon

In this study, mesoporous carbon (MC) supported nano Fe0 was prepared from polyvinyl alcohol (PVA) using MnCO3 as template, which was used as the catalyst to activate persulfate (PS) for the removal of tetracycline hydrochloride (TC) from aqueous solution. The nano Fe0 was immobilized on MC by liquid phase reduction to overcome the drawbacks of nano Fe0 for persulfate (PS) activation, including being easily aggregated and oxidized. The experimental results showed that the nano Fe0/MC + PS system achieved 92.1% of TC removal, while the MC + PS system and nano Fe0 + PS systems showed 78.5% and 33.7% of TC removal, respectively. High removal efficiency in the nano Fe0/MC + PS system could be attributed to the superior PS activation capability due to the synergistic effects of nano Fe0 and MC. In order to better understand the removal mechanism, the effects of nano Fe0 loading amount (c), dosage (m), PS/TC mole ratio (Rm) and initial pH on TC removal were evaluated in the nano Fe0/MC + PS system. The results showed that the removal efficiency of TC was enhanced with the increase of nano Fe0 loading amount and dosage, while slightly decrease with the increase of PS/TC mole ratio. The maximum removal of TC was 97.7% under the optimal conditions: c = 20%, m = 0.8 g/L, Rm = 50/1 and pH = 5. According to the results of radical scavengers’ studies and intermediates analysis, SO4−, which was produced from catalytic activation of PS by nano Fe0 and Fe2+ on the surface of Fe0/MC, plays a significant role for TC degradation in the nano Fe0/MC + PS system. The Fe0/MC + PS system exhibited a superior oxidation process for the removal of TC from aqueous solution with excellent stability and reusability of Fe0/MC.

Synergic mechanism of adsorption and metal-free catalysis for phenol degradation by N-doped graphene aerogel

3D porous N-doped reduced graphene oxide (N-rGO) aerogels were synthesized by a hydrothermal reduction of graphene oxide (GO) with urea and following freeze-drying process. N-rGO aerogels have a high BET surface of 499.70 m2/g and a high N doping content (5.93–7.46 at%) including three kinds of N (graphitic, pyridinic and pyrrolic). Their high catalytic performance for phenol oxidation in aqueous solution was investigated by catalytic activation of persulfate (PS). We have demonstrated that N-rGO aerogels are promising metal-free catalysts for phenol removal. Kinetics studies indicate that phenol degradation follows first-order reaction kinetics with the reaction rate constant of 0.16799 min−1 for N-rGO-A(1:30). Interestingly, the comparison of direct catalytic oxidation with adsorption-catalytic oxidation experiments indicates that adsorption plays an important role in the catalytic oxidation of phenol by decreasing the phenol degradation time. Spin density and adsorption modeling demonstrates that graphitic N in N-rGO plays the most important role for the catalytic performance by inducing high positive charge densities to adjacent carbon atoms and facilitating phenol adsorption on these carbon sites. Furthermore, the activation mechanism of persulfate (PS) on N-rGO was first investigated by DFT method and PS can be activated to generate strongly oxidative radical (SO4·-) by transferring electrons to N-rGO.