Degradation of Bisphenol A using peroxymonosulfate activated by one-step prepared sulfur-doped carbon nitride as a metal-free heterogeneous catalyst
TL;DR: In this article, a one-step prepared sulfur-doped carbon nitride (CNS) was employed as a non-metal and easy-to-prepare catalyst to activate peroxymonosulfate (PMS) to generate sulfate radicals for BPA degradation.
About: This article is published in Chemical Engineering Journal.The article was published on 2017-04-01. It has received 236 citations till now.
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TL;DR: In this article, a critical review on the recent practical and theoretical development in graphene and carbon nanotubes (CNTs)-based materials as carbocatalysts for the activation of peroxymonosulfate (PMS) and peroxydisulfate(PDS).
398 citations
TL;DR: In this article, different photo-activated Sulfate radical (SO4 −)-based advanced oxidation process (SR-AOP) under light irradiation (ultraviolet (UV) light, visible light or simulated solar light) is considered as a prospective method for refractory organic pollutants degradation.
345 citations
TL;DR: In this paper, a series of nitrogen-doped carbon nanotubes (NCNTFs) with distinguishable nitrogen content and graphitization degree have been successfully prepared through in situ transformation of ZIF-67 under N2/H2 atmosphere at different pyrolysis temperature.
310 citations
TL;DR: In this paper, a metal organic framework (ZIF-8)-derived nitrogen doped carbon modified g-C3N4 heterostructured composite was synthesized through a facile thermal treatment method.
Abstract: Designing metal-free g-C3N4 based photocatalytic system with efficient photocatalytic activity has received enormous attention in the field of environmental remediation because of its great potential for removing refractory contaminants. Herein, a novel metal organic framework (ZIF-8)-derived nitrogen doped carbon (ZIF-NC) modified g-C3N4 heterostructured composite was synthesized through a facile thermal treatment method. Benefiting from the hierarchical porosity, conductive network, and abundant exposed active sites for peroxymonosulfate (PMS) activation of MOF-derived nitrogen doped carbon, the introduction of MOF-derived nitrogen doped carbon into g-C3N4 not only facilitates the charge separation of g-C3N4 but also greatly accelerates PMS activation to yield high active SO4 − radical. The energy band diagrams derived from Mott-Schottky, valence band X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy studies indicate that the formed heterojunction between g-C3N4 and ZIF-NC is Schottky type. The ZIF-NC with lower Fermi level energy can serve as an excellent electron accepter to enable fast electron transfer from the conduction band of g-C3N4 to ZIF-NC and boost the charge separation of g-C3N4. Photoelectrochemical tests combined with multiple spectroscopic techniques further confirm the enhanced charge carrier separation performance of composite. As a result, the as-prepared hybrids displayed remarkably improved photocatalytic activities toward bisphenol A (BPA) degradation in the presence of PMS under visible light irradiation. The apparent rate constant, k, for BPA degradation of the ZIF-NC/g-C3N4 composites with PMS is approximately 8.6 times as high as that of bare g-C3N4. This work provides a promising approach on the rational design of high-performance, cost-effective photocatalysts for environmental remediation.
302 citations
TL;DR: In this article, porous nitrogen-doped carbon (PNC) microspheres derived from Zn-Co Prussian blue analogues (ZnCo PBAs) are employed as heterogeneous catalysts in peroxymonosulfate (PMS) activation.
Abstract: Nitrogen-doped carbon materials are becoming a new type of metal-free heterogeneous catalysts in advanced oxidation processes (AOPs) for wastewater treatment and environmental remediation. In this study, porous nitrogen-doped carbon (PNC) microspheres derived from Zn–Co Prussian blue analogues (Zn–Co PBAs) are employed as heterogeneous catalysts in peroxymonosulfate (PMS) activation. The unique configuration of the metal centers/clusters bound by cyanide groups (–CN) of Zn–Co PBAs offers the PNC microspheres abundant porosity, a high graphitization degree, and rich nitrogen substitution, which lead to improvements in the catalytic performance. PNC-800 (pyrolyzed at 800 °C) exhibits better performance than other common carbon materials and homologous nitrogen-doped carbocatalysts derived from ZIF-8/ZIF-67. Based on radical quenching and trapping experiments, a non-radical pathway is proposed to dominate methylene blue (MB) degradation; and the high graphitization degree and rich surface graphitic N sites of PNC-800 are two key factors that induce the non-radical pathway. Several influential factors, including catalyst dosage, PMS concentration, pH value and reaction temperature, are investigated in detail. Notably, MB degradation over PNC-800 is almost completely insusceptible to common ions and natural organic matter, and maintains its catalytic efficiency under the background conditions of several real water samples. More interestingly, this non-radical pathway and the good catalytic performance of the PNC-800/PMS system are universal in the degradation of other typical organic pollutants. We believe that these PNC microspheres may be a promising green heterogeneous catalyst for the degradation of organic pollutants, and this study can be used for the design of high-performance carbocatalysts in non-radical systems in the future.
232 citations
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TL;DR: The homogeneous substitution of sulfur for lattice nitrogen and a concomitant quantum confinement effect are identified as the cause of this unique electronic structure and the excellent photoreactivity of C(3)N(4-x)S(x), which may shed light on general doping strategies for designing potentially efficient photocatalysts.
Abstract: Electronic structure intrinsically controls the light absorbance, redox potential, charge-carrier mobility, and consequently, photoreactivity of semiconductor photocatalysts. The conventional approach of modifying the electronic structure of a semiconductor photocatalyst for a wider absorption range by anion doping operates at the cost of reduced redox potentials and/or charge-carrier mobility, so that its photoreactivity is usually limited and some important reactions may not occur at all. Here, we report sulfur-doped graphitic C(3)N(4) (C(3)N(4-x)S(x)) with a unique electronic structure that displays an increased valence bandwidth in combination with an elevated conduction band minimum and a slightly reduced absorbance. The C(3)N(4-x)S(x) shows a photoreactivity of H(2) evolution 7.2 and 8.0 times higher than C(3)N(4) under lambda > 300 and 420 nm, respectively. More strikingly, the complete oxidation process of phenol under lambda > 400 nm can occur for sulfur-doped C(3)N(4), which is impossible for C(3)N(4) even under lambda > 300 nm. The homogeneous substitution of sulfur for lattice nitrogen and a concomitant quantum confinement effect are identified as the cause of this unique electronic structure and, consequently, the excellent photoreactivity of C(3)N(4-x)S(x). The results acquired may shed light on general doping strategies for designing potentially efficient photocatalysts.
1,762 citations
TL;DR: The photodegradation mechanisms for two typical dyes, rhodamine B (Rh B) and methyl orange (MO), are proposed based on comparison experiments and the electron paramagnetic resonance was used to detect the active species for the photodegrading reaction over g-C(3)N(4).
Abstract: Graphitic carbon nitride (g-C3N4) and boron-doped g-C3N4 were prepared by heating melamine and the mixture of melamine and boron oxide, respectively. X-ray diffraction, X-ray photoelectron spectroscopy, and UV−vis spectra were used to describe the properties of as-prepared samples. The electron paramagnetic resonance was used to detect the active species for the photodegradation reaction over g-C3N4. The photodegradation mechanisms for two typical dyes, rhodamine B (Rh B) and methyl orange (MO), are proposed based on our comparison experiments. In the g-C3N4 photocatalysis system, the photodegradation of Rh B and MO is attributed to the direct hole oxidation and overall reaction, respectively; however, for the MO photodegradation the reduction process initiated by photogenerated electrons is a major photocatalytic process compared with the oxidation process induced by photogenerated holes. Boron doping for g-C3N4 can promote photodegradation of Rh B because the boron doping improves the dye adsorption and...
1,495 citations
TL;DR: Graphitic carbon nitride (g-C3N4) was produced on a large scale by pyrolysis of urea under ambient pressure without additive assistance as mentioned in this paper.
Abstract: Graphitic carbon nitride (g-C3N4) was produced on a large scale by the pyrolysis of urea under ambient pressure without additive assistance. The retainable pyrolysis-generated self-supporting atmosphere and the reaction temperature are two necessary conditions. This g-C3N4 as photocatalyst shows recyclable adsorption and photocatalytic activity under visible light.
1,343 citations
TL;DR: In this article, the degradation of polychlorinated biphenyls (PCBs) using sulfate radical-based advanced oxidation processes (SR-AOPs) was investigated.
Abstract: Polychlorinated biphenyls (PCBs) in the environment pose long-term risk to public health because of their persistent and toxic nature. This study investigates the degradation of PCBs using sulfate radical-based advanced oxidation processes (SR-AOPs). These processes are based on the generation of sulfate radicals through iron (Fe(II), Fe(III)) mediated activation of peroxymonosulfate (KHSO 5 , PMS) or persulfate (Na 2 S 2 O 8 , PS). This study is the first instance for coupling of Fe(II)/Fe(III) with PMS for PCB degradation in aqueous and sediment systems. The high oxidation efficiencies of the free radicals (SO 4 − ), in combination with the slow rate of consumption of the oxidants, make these processes very effective for the degradation of recalcitrant organic compounds. The effectiveness of the process was evaluated based on the degradation of a model polychlorinated biphenyl, 2-chlorobiphenyl and total organic carbon (TOC) removal. The kinetics of 2-chlorobiphenyl degradation along with the effect of oxidant and catalyst concentrations on the degradation efficiency was studied. Near complete removal of 2-chlorobiphenyl was observed when Fe(II) was used with PMS or PS. Fe(II) acts as a sulfate radical scavenger at higher concentrations indicating that there is an optimum concentration of Fe(II) that leads to most effective degradation of the target contaminant. A chelating agent, sodium citrate, was used to control the quantity of iron in the solution for activation of the oxidant. For the first time, we studied the feasibility of the activation of PMS using iron citrate complexes for PCB degradation. In the presence of sodium citrate, increase in degradation efficiency was observed up to a metal:ligand ratio of 1:2, after which the increase in citrate concentration led to a decrease in removal efficiency. Fe(II)/PMS systems were found to be very effective in degrading PCB in a sediment-slurry system with more than 90% PCB removal being observed within 24 h.
943 citations
TL;DR: This study presents a novel metal-free catalyst for green remediation of organic pollutants in water that can effectively break the inertness of carbon systems, activate the sp(2) -hybridized carbon lattice and facilitate the electron transfer from covalent graphene sheets for PMS activation.
Abstract: S ulfur and nitrogen co-doped reduced graphene oxide (rGO) is synthesized by a facile method and demonstrated remarkably enhanced activities in metal-free activation of peroxymonosulfate (PMS) for catalytic oxidation of phenol. Based on fi rst-order kinetic model, S‐N co-doped rGO (SNG) presents an apparent reaction rate constant of 0.043 ± 0.002 min −1 , which is 86.6, 22.8, 19.7, and 4.5-fold as high as that over graphene oxide (GO), rGO, S-doped rGO (S-rGO), and N-doped rGO (N-rGO), respectively. A variety of characterization techniques and density functional theory calculations are employed to investigate the synergistic effect of sulfur and nitrogen co-doping. Co-doping of rGO at an optimal sulfur loading can effectively break the inertness of carbon systems, activate the sp 2 -hybridized carbon lattice and facilitate the electron transfer from covalent graphene sheets for PMS activation. Moreover, both electron paramagnetic resonance (EPR) spectroscopy and classical quenching tests are employed to investigate the generation and evolution of reactive radicals on the SNG sample for phenol catalytic oxidation. This study presents a novel metal-free catalyst for green remediation of organic pollutants in water.
537 citations