Degradation Of P-nitrophenol Research Articles

The enhanced peroxymonosulfate activation ability and mechanism on low-coordinated Fe-N3 single sites for organic pollutant degradation in wastewater

For boosting the intrinsic peroxymonosulfate (PMS) catalytic activity of single atom catalysts (SACs), we fabricate zeolitic imidazolate framework (ZIF)-derived Fe SAC with different nitrogen coordination numbers (denoted as Fe-Nx/C) to boost organic pollutant oxidation. X-ray absorption fine structure (XAFS) spectroscopy was undertaken to determine the coordination configuration of Fe–N path. As expected, the resultant Fe-N3/C exhibited more excellent PMS catalysis activity with a p-nitrophenol (4-NP) degradation kinetic rate constant (kobs) of 0.061 min−1 that is 2.4-fold enhancement relative to the Fe-N4/C. Electron paramagnetic resonance (EPR) measurements and quenching tests confirmed the 1O play the main role associated with high-valent Fe–oxo and a small amount of OH and SO4− species. Density functional calculations revealed that low coordinated Fe–N3 sites prefer to form a bridge coordination bond structure of O-Fe-O with the adsorption sites of O2 and O1 in PMS molecule, exhibiting stronger interaction with the oxidant and better electron donating capability to enhance PMS activation comparing to common Fe-N4 structure based on charge deformation density, electron localization function (ELF) and projected density of state (PDOS) analysis. These findings indicate that microstructure modulation is a useful avenue to prepare a high-performance Fenton-like SACs.

Rapid degradation of p-nitrophenol with O3 in the presence of Co2(OH)3Cl as a catalyst

A Co2(OH)3Cl catalyst was prepared by deep eutectic solvent and applied to decompose p-nitrophenol (4-NP) by O3. Within 30 min, the removal efficiency of Co2(OH)3Cl catalyst for 4-NP reached 92.9%, which is much higher than that of Co(OH)2 or Co3O4 catalyst. In a wide pH range (3–11), the catalyst showed good catalytic performance for 4-NP removal. The production of highly active free radicals such as 1O2 and O2− is conducive to efficient degradation. Furthermore, the catalyst showed good stability and recoverability.

Graphene oxide-coated Ag-TiO2 hybrid nanocomposites for superior photocatalytic activity.

Graphene oxide (GO) has now emerged as one of the most promising materials in different areas such as photocatalysis, adsorption, and energy storage due to its high surface area, unique layered structure, etc. Among various types of precursors, anthracite coal has attracted a lot of attention nowadays as it affords GO a high concentration of sp2 carbons resulting in high conductivity and superior absorbance in the visible region. In this report, we have prepared GO-TiO2 nanocomposites as it is supposed to possess high photocatalytic activity owing to facile electron transmission from the conduction band of TiO2 to the GO surface resulting in a much lower degree of electron-hole pair recombination. To boost the photocatalytic activity further, TiO2 was coated with Ag nanoparticles as well. These hybrid structures were characterized by different analytical techniques, for example, XRD, HR-TEM, SEM, and Raman spectroscopy. The XRD pattern of these composites consists of characteristic peaks corresponding to GO, TiO2, and Ag. The HR-TEM studies confirm the presence of GO layers, cube-shaped TiO2, and spherical Ag nanoparticles. Phenol and 4-nitrophenol have been used as model pollutants to evaluate the photooxidation efficiencies under both UV and visible light irradiation. Under UV irradiation, the GO/Ag-TiO2 ternary nanocomposite shows better photooxidation efficiency (62%) compared to Ag-TiO2 (38%), GO-TiO2 (9%), GO (17%), and TiO2 (8%) toward phenol degradation. The GO/Ag-TiO2 is also having the highest photocatalytic activity toward the removal of phenol under visible light irradiation (34%). The ternary heterostructure (85%) also possesses superior photooxidation activity compared to Ag-TiO2 (44%) and GO-TiO2 (71%) toward the degradation of p-nitrophenol under UV light radiation for 60 min. The above observation reveals that the cooperative effect of Ag, TiO2, and GO is playing a crucial role to result in the high photooxidation activity of the GO/Ag-TiO2 hetero-nanocomposites.

The degradation of p-nitrophenol by biochar is dominated by its electron donating capacity

The typical aromatic and phenolic pollutant, p-nitrophenol (PNP), is extensively used in the industry and can seriously threaten the environmental health. Biochar, as a solid carbon-rich material, can directly degrade PNP. It has been reported that the PNP degradation by biochar is closely related to the electron exchange capacity of biochar (the sum of electron donating and accepting capacities). However, the roles of electron donating and accepting capacity of biochar in PNP degradation have not been distinguished before. In this study, the biochar samples were chemically modified to manipulate the electron donating and accepting capacities of biochar samples. Compared with pristine biochar (3.67 %), modified biochar had higher degradation efficiencies of PNP (>7.81 %). The strictly positive correlation between the electron donating capacities and the PNP degradation rates of biochar samples (r = 0.98, p < 0.05) indicated that the PNP degradation process by biochar is dominated by the reduction process. Although both the oxidation and reduction degradation products were found in the degradation system, the quenching experiment of OH, a key radical in the process of oxidation degradation, further proved that the oxidation process just played a minor role (<10 %) in the PNP degradation by biochar. This study shed light on the degradation mechanism of PNP by biochar and could promote the application of biochar in the pollution remediation.

Simple preparation of monolithic N-doped electrode for efficient EF remediation of petrochemical wastewater: Performance, degradation pathways, and mechanism of different N-doped positions

Developing metal-free N-doped electrode for efficient electro-Fenton (EF) application is significant for petrochemical wastewater treatment considering the serious water pollution problem that caused by petrochemical industry. Herein, a robust monolithic N-doped electrode was fabricated by simple physical mixing and heating methods using accessible raw materials, and applied in EF system for wastewater treatment. The prepared 3D NC-650 electrode was used as cathode, showing excellent catalytic activity and stability for degradation of typical p-nitrophenol (PNP) pollutant and remediation of petrochemical wastewater. During the EF process, the PNP was completely decomposed via the substitution, oxidation, and ring-opening reactions under the attack of ·OH. The degradation pathways of organics in real wastewater matrix were also revealed based on liquid chromatography-mass spectrometry and three-dimensional fluorescence analysis. According to the degradation experiments, microstructure analysis, and theoretical calculation (molecular electrostatic potential, bond length, and adsorption energy), the possible mechanism of different N-doped positions on the monolithic 3D NC-650 electrode was revealed, in which the graphitic N, edge pyridinic N, and edge pyrrolic N all contribute to enhance the EF activity by accelerating the O2 adsorption, facilitating the H2O2 formation by promotion of *–OOH bond breaking, and promoting the adsorption of organics on electrode surface, respectively. This work illustrates insights into the EF reaction mechanism with the monolithic N-doped electrode, and thus accelerates its application for actual wastewater remediation.

Visible light photo-Fenton catalytic properties of starch functionalized α-FeOOH/β-FeOOH/Cu2O p-n-p heterojunction nanostructures

Photocatalysts with p-n-p heterojunctions can result in efficient charge separation. This idea motivated the synthesis of starch functionalized α-FeOOH/β-FeOOH/Cu2O heterojunction nanocomposites. All components in the composite have visible range band gaps. In a step-wise procedure, Cu2O nanostructures were precipitated on starch functionalized α-FeOOH/β-FeOOH nanocomposites. Mott Schottky plots confirmed p-n-p heterojunction formation. It enhanced charge separation and slowed down recombination resulting in efficient visible-light photocatalytic activity. The activity of this photocatalyst was evaluated for the photo-Fenton degradation of p-nitrophenol (PNP) and methyl orange (MO). Both degradation reactions follow zero-order kinetics. The photocatalyst remained stable during the organic pollutant degradation process even after repeated use.

N-doped carbon nanoflakes coordinate with amorphous Fe to activate ozone for degradation of p-nitrophenol

Due to their high catalytic performance, metal nitrogen-doped carbon materials are widely used in the field of environmental restoration of polluted water but there is limited research on metal nitrogen doped carbon composite materials as ozone catalysts. Herein, we report the preparation of amorphous iron-coordinated nitrogen-doped carbon nanosheets as a catalyst for ozone by the coordination of Fe-metal ions at the end of phenol chain in the lignin network. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy (Raman), powder X-ray diffraction (XRD) and element mapping were used to characterize the Fe/D-NC composite material and investigate its morphology and composition. Highly uniform distribution of iron species was found through characterization. By exploring the degradation performance of composite materials of Fe/D-NC-T (700，800，900 ℃) prepared at different temperatures, it was found that the optimal Fe/D-NC-800 could effectively degrade p-nitrophenol (PNP) within 30 min. Quenching experiments and ESR analysis showed that both free and non-free radicals (•OH, O2•− and 1O2) and intrinsic Lewis acid sites (LAS) of the composite material Fe/D-NC-800 were involved and responsible for the degradation of PNP. This work not only offers new platforms for catalytic ozonation and may drive the development of metal-lignin-based catalytic ozonation for effective water treatment but also opens new avenues toward lignin valorization and biomass economy.

Enhanced microbial degradation mediated by pyrogenic carbon toward p-nitrophenol: Role of carbon structures and iron minerals

Pyrogenic carbon (PC) including black carbons and engineered carbons can mediate the extracellular electron transfer to facilitate the biogeochemical reaction with organic pollutants. Yet, the role of carbon structures and iron minerals on PC-mediated microbial degradation is still lacking of understanding. Herein, we studied the electrochemical properties of PCs produced from varied feedstock with regards to the mediated degradation of p-nitrophenol (PNP) by Shewanella putrefaciens CN32 in anoxic system. Mediated degradation by PCs was enhanced by facilitating extracellular electron transfer through oxygenated group and graphitic structure. Graphitic crystallites improved the electron-accepting capacity (as suggested by ID/IG and EAC) and diminished the electrochemical impedance (as suggested by Rct), contributing to PNP degradation under the anoxic system. Furthermore, more interfacial adsorption was conducive to the mediated reduction by the graphitic structure on PCs of high-temperature. In the presence of iron minerals, both hematite and goethite significantly facilitated PC-mediated degradation, which could be ascribed to the enhancement of the electron-donating capacity of microorganism and the accumulation of the reductive-state PCs by the interaction with generated Fe(II). This work paves a feasible way to the technical design on the remediation of phenolic contaminants by PC-mediated microbial degradation in environment.

The Modification Mechanism of Lanthanum Doping in Ti/Sb-SnO2Electrode and its Electrocatalytic Behavior of Degradation of p-nitrophenol

The Modification Mechanism of Lanthanum Doping in Ti/Sb-SnO2Electrode and its Electrocatalytic Behavior of Degradation of p-nitrophenol

Degradation of p-Nitrophenol by activated persulfate with carbon-based materials

The removal of p-nitrophenol (PNP) from wastewater was evaluated by the activated persulfate process using different materials – carbon xerogels (XG), carbon nanotubes (CNT), and activated carbon (AC) –, and also using such materials doped with nitrogen (XGM, CNTM and ACM). These carbon materials were impregnated with 2 wt.% of iron and tested in the oxidative process to assess the influence of their textural and surface chemical properties. The carbon-based materials' properties influence the efficiencies of the adsorption and oxidative processes; in adsorption, the materials with higher specific surface areas (SBET), i.e. AC (824 m2/g) and Fe/AC (807 m2/g), have shown to be the most promising (having achieved a PNP removal of about 20%); on the other hand, in the activated persulfate process the carbon or iron-containing carbon materials with the highest mesoporous areas (Smeso) were the preferential ones – XG and Fe/XG, respectively – reaching removals of 47.3% and 75.7% for PNP and 44.9 and 63.3% for TOC, respectively. Moreover, the presence of nitrogen groups on the samples’ surface benefits both processes, being found that PNP degradation and mineralization increase with the nitrogen content. The stability of the best materials (XGM and Fe/XGM) was evaluated during four cycles, being noticed that while XGM lost catalytic activity, the Fe/XGM sample remained stable without leaching of iron. The quantification of intermediate compounds formed during persulfate oxidation was performed, and only oxalic acid was detected, in addition to PNP, being that their contribution to the TOC measured was higher than 99%. Experiments carried out in the presence of radical scavengers proved that only the sulfate radical is present under the acidic conditions used. Complete PNP oxidation and TOC removal of ∼96% were reached for the activated persulfate process, proving to be more attractive than the Fenton one.

Ultrasonic-electrodeposition construction of high hydrophobic Ce-PDMS-PbO2/SS electrode for p-nitrophenol degradation: Catalytic, kinetics and mechanism

In this work, a novel hydrophobic microsphere Ce-PDMS-PbO2 structure on stainless steel (SS) was prepared via ultrasonic-electrodeposition as an efficient anodic electrocatalyst for p-nitrophenol (PNP) degradation. Compared to PbO2/SS, such Ce-PDMS-PbO2/SS electrode exhibits obviously lower activation energy (19.20 kJ mol−1) and charge transfer resistance (3.268 Ω cm−2), tolerable stability, higher exchange current density (1.171 ×10−5 A cm−2) and electrochemical active area (202.0 cm2). The as-synthesized Ce-PDMS-PbO2/SS anode achieved drastically enhanced PNP removal efficiency of 96.9% in 120 min, and the degradation reaction-order was calculated to be 0.9123 conformed to the quasi-first-order reaction kinetics. The GC-MS results reveal the possible PNP degradation pathway under the action of both anodic and cathodic reactions. Furthermore, the DFT calculation results show that Ce doping can decrease the activation energy barrier of ·OH and promote the ·OH generation. Overall, this work offers a new strategy and comprehension to construct a high-efficiency electrode for PNP pollutants degradation.

Permanganate activation by glucose-derived carbonaceous materials for highly efficient degradation of phenol and p-nitrophenol: Formation of hydroxyl radicals and multiple roles of carbonaceous materials

Owing to its inertness toward refractory organic pollutants and the release of Mn2+, the use of permanganate was limited in soil and groundwater remediation. The present study proposed an improvement strategy based on glucose-derived carbonaceous materials, which enhanced the potential of permanganate degrading organic pollutants. The glucose-derived carbonaceous material with 1000 °C charring temperature was named C1000, which was exploited in activating KMnO4 for the elimination of refractory organic contaminants. The addition of C1000 in the KMnO4 system triggered the degradation of refractory p-nitrophenol and quicken phenol degradation. Unlike the detection of Mn(III) species in a solo KMnO4 system, the presence of C1000 facilitated the formation of •OH in the KMnO4 system, which was confirmed by the use of quenchers such as methanol, benzoic acid, tertiary butanol, and carbonate. Additionally, the glucose-derived carbonaceous material played multiple roles in improving the performance of permanganate, including the enrichment of organic pollutants, donation of electrons to permanganate, and acting as an electron shuttle to facilitate the oxidation of organic pollutants by permanganate. The study's novel findings have the potential to expand the use of permanganate in the remediation of organic pollutants.

Enhanced Decomposition of H2O2 Using Metallic Silver Nanoparticles under UV/Visible Light for the Removal of p-Nitrophenol from Water

Three Ag nanoparticle (NP) colloids are produced from borohydride reduction of silver nitrate in water by varying the amount of sodium citrate. These nanoparticles are used as photocatalysts with H2O2 to degrade a p-nitrophenol (PNP) solution. X-ray diffraction patterns have shown the production of metallic silver nanoparticles, whatever the concentration of citrate. The transmission electron microscope images of these NPs highlighted the evolution from spherical NPs to hexagonal/rod-like NPs with broader distribution when the citrate amount increases. Aggregate size in solution has also shown the same tendency. Indeed, the citrate, which is both a capping and a reducing agent, modifies the resulting shape and size of the Ag NPs. When its concentration is low, the pH is higher, and it stabilizes the formation of uniform spherical Ag NPs. However, when its concentration increases, the pH decreases, and the Ag reduction is less controlled, leading to broader distribution and bigger rod-like Ag NPs. This results in the production of three different samples: one with more uniform spherical 20 nm Ag NPs, one intermediate with 30 nm Ag NPs with spherical and rod-like NPs, and one with 50 nm rod-like Ag NPs with broad distribution. These three Ag NPs mixed with H2O2 in water enhanced the degradation of PNP under UV/visible irradiation. Indeed, metallic Ag NPs produce localized surface plasmon resonance under illumination, which photogenerates electrons and holes able to accelerate the production of hydroxyl radicals when in contact with H2O2. The intermediate morphology sample presents the best activity, doubling the PNP degradation compared to the irradiated experiment with H2O2 alone. This better result can be attributed to the small size of the NPs (30 nm) but also to the presence of more defects in this intermediate structure that allows a longer lifetime of the photogenerated species. Recycling experiments on the best photocatalyst sample showed a constant activity of up to 40 h of illumination for a very low concentration of photocatalyst compared to the literature.

Enhanced heterogeneous Fenton degradation of p-nitrophenol by Fe3O4 nanoparticles decorated cellulose aerogel from banana stem

Fe3O4 nanoparticles decorated on cellulose aerogel (CA) from banana stems (Fe3O4@CA) were synthesized for application in the Fenton degradation of p-nitrophenol (PNP). Cellulose aerogel extracted from raw banana stems was synthesized with kymene as a crosslinking agent and freeze-dried method. The Fe3O4@CA samples were characterized by X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDS), Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM), X-ray photoelectron spectroscopy (XPS). The samples with different contents of Fe3O4 on cellulose aerogel were investigated for the degradation yield of PNP in water. The affect of the loaded content of Fe3O4 and H2O2 concentration on the PNP treatment efficiency were also investigated to suggest suitable values including the Fe3O4 catalyst content loaded on CA of 0.40 g/g and the H2O2 concentration of 5.0 g/L. As the results, Fe3O4@CA reached the removal efficiency of 87.92% in 100 mins to obey the pseudo-first kinetic model with a reaction rate constant of 0.0301 min−1. This study’s finding provides a method for creating environmentally friendly catalytic material, which might be used in green chemical engineering.

Enhanced photocatalytic activity of p-nitrophenol degradation by Fe–In2S3 material driven by visible light

The Fe–In2S3 nanoparticles were synthesized by an improved reflux method and characterized with kinds of analytical and spectral techniques to confirm their compositional surface morphology, crystal structure, optical and photocatalytic properties. Compared with pure In2S3, Fe-doped In2S3 displayed higher photocatalytic performance in the degradation of p-nitrophenol (PNP) under visible light. The photocatalytic degradation effect came to the best when the molar mass ratio of In:Fe was 95:5 (the degradation efficiency of PNP was 98.86% within 100 min under illumination conditions) and its reaction rate was about 25 times that of pure In2S3. Meanwhile, the mechanism of enhanced photocatalytic activity by doping photocatalysts was explored. The enhanced photocatalytic activity of Fe–In2S3 was attributed to the absorption edge red-shift, the narrowing of the bandgap, and the photolysis behavior of iron complexes. Finally, possible active species and mechanisms were discussed in detail according to the above experimental results.

Bifunctional technology involving RuO2-IrO2/Ti electrode decorated with reduced graphene oxide aerogel with Pd nanoparticles: Electrochemical oxidative decomposition and detection of p-nitrophenol

In this study, a nanocomposite containing a reduced-graphene-oxide aerogel decorated with Pd nanoparticles (rGO-A/Pd-NP), an rGO-A/Pd-NP sensor, and a RuO2–IrO2–rGO-A/Pd-NP composite electrode were prepared to electrochemically detect p-nitrophenol and elucidate the mechanism underlying electrochemical oxidative p-nitrophenol degradation. The composite electrode exhibited an outstanding electrolytic p-nitrophenol removal efficiency (96.1%) in addition to a noteworthy chemical oxygen demand and total-organic-carbon removal efficiency (88.4% and 70.2%, respectively). Optimal p-nitrophenol decomposition was achieved using an initial p-nitrophenol concentration of 50 mg mL−1, a pH of 3, and a current density of 40 mA cm−2. p-Nitrophenol was found to decompose via electrochemical oxidation by hydroxyl radicals generated on the anode surface, with the reaction following pseudo-first-order kinetics. The rGO-A/Pd-NP sensor showed excellent reduction-based p-nitrophenol sensing performance (linear range, 0.1–20 mg L−1 [R2 = 0.9919]; detection limit, 0.052 mg L−1). Overall, an organic contaminant in natural water was rapidly detected using a sensor electrodeposited with the rGO-A/Pd-NP nanocomposite, and the electrolytic p-nitrophenol removal efficiency was improved by incorporating functional rGO-A/Pd-NP particles into a Ti/RuO2–IrO2 electrode. The convergent technology reported herein for detecting and removing harmful substances will open a new avenue for nanocomposite catalyst applications in electroanalytical chemistry.

Construction of carbon nitride-based heterojunction as photocatalyst for peroxymonosulfate activation: Important role of carbon dots in enhancing photocatalytic activity

Strategic combination of carbon dots (CDs) and carbon nitride (CN) has provided an appealing strategy to synthesize metal-free carbonaceous catalyst for environmental-concerned photocatalytic applications. However, there still exists an ambiguous cognition on the relationship between functional structures of CDs and enhanced photocatalytic activity of CDs/CN composites. Herein, different types of functionalized CDs were physically integrated with CN matrix to construct CDs/CN heterojunctions. By systematically investigating the efficiency of CDs/CN-catalyzed peroxymonosulfate (PMS) in p-nitrophenol degradation, we revealed that the CDs enriched with carboxyl groups or doped by pyrrolic-N inclined to attract photogenerated electrons from CN host, and thus contributed to the photocarriers separation. As such, these CDs-imparted active sites can dramatically facilitate PMS activation, and further p-nitrophenol degradation by photogenerated holes and multiple reactive oxygen radicals. Nonetheless, the CDs mainly doped by electron-donating graphitic-N could form electron-rich regions at the interface of CN host upon forming heterojunction, thus making barriers against charge separation in the PMS-mediated oxidation process. Taken together, this study will shed light on the rational design of CDs/CN heterojunctions with high photocatalytic activity.

Polymeric multi-composites with a tailored nickel microenvironment as catalytic flow-through membrane reactors for efficient p-nitrophenol degradation

The catalytic degradation of environmental pollutants like p-nitrophenol is a promising approach for wastewater treatment. For this, it would be very beneficial to increase the catalytic efficiency of abundant non-noble metals and to fabricate materials that enable a continuous water treatment. In this work, a polymer-based membrane platform was established in a novel approach to immobilize nickel nanoparticles next to an adjustable multi-composite environment that improves the nickel activity for the catalytic hydrogenation of p-nitrophenol using borohydride. An optimized film casting and phase separation method with polyethersulfone as matrix polymer enabled the one-step fabrication of membranes with high loadings (53 wt%) of nickel nanoparticles, carbon nanoparticles and cationic ionomer, as well as high porosity (75%). The addition of carbon and ionomer optimized the nickel microenvironment in the porous membranes and doubled the p-nitrophenol turnover frequency in batch reaction. This is likely due to the utilization of in situ formed hydrogen by the carbon nanoparticles and the function of the cationic ionomer to bind p-nitrophenol and borohydride next to active sites. Combining these synergies between the functional additives with flow through the porous catalytic membrane reactors led to up to 10 times higher turnover frequencies and to an increase of reaction rate constants normalized to the nickel mass from 0.5 s−1 g−1 for dispersed nanoparticles to 140 s−1 g−1 for the best membrane. The multi-composite membranes also exhibit exceptional stability which enabled a continuous water treatment in flow-through for high p-nitrophenol concentration (50 mM or 7 g/L).

A novel pigeon waste based biochar composite for the removal of heavy metal and organic compound: Performance, products and mechanism

Recently, a large number of agricultural wastes have been extensively converted into biochar based materials, these biochar materials have been popularly employed in the removal of various pollutants from environment. Herein, a novel pigeon waste based biochar composite (FeBC) was firstly synthesized and applied for hexavalent chromium (Cr(VI)) and p-nitrophenol (PNP) adsorption in water. The most relevant findings showed that FeBC exhibited a superior performance on Cr(VI) and PNP adsorption compared with pristine biochar. The Cr(VI) monolayer adsorption onto FeBC might be dominant, and Cr(VI) adsorption by FeBC was an endothermic process. Both Cr(VI) and PNP adsorption behavior were well fitted with the pseudo-second-order kinetic model, Elovich, intra-particle diffusion (IPD), liquid film diffusion kinetic (LFD) and chemical reaction models. Both the pathway of PNP degradation and mechanism for Cr(VI) and PNP adsorption over FeBC were proposed. Almost half of Cr(VI) was reduced into Cr2O3 and Cr(OH)3, both reduction and precipitation reactions might be dominant in Cr(VI) adsorption. O2•−, 1 O2 and •OH were involved in PNP removal reaction, but the contribution of •OH was small. The oxidation, π-π interaction and hydrogen bonds interactions might be involved in this PNP removal process, and PNP was oxidized to form several intermediates via hydroxylation and ring cleavage reactions. This study could provide a novel treatment strategy for the simultaneous decontamination of effluents combined with heavy metals and organic compounds in realistic remediation application.

Fe-embedded ZIF-derived N-doped carbon nanoparticles for enhanced selective reduction of p-nitrophenol

The selective catalytic reduction of nitroaromatics towards aromatic amines under mild reaction condition is an important approach to reduce the toxicity of waste effluents from industry and afterwards utilize the product as important fine organic chemical raw materials. P-nitrophenol (PNP) is chosen as the probe molecule of nitroaromatics in this study. A Fe-embedded N-doped Carbon (Fe-N-C) catalyst prepared using ZIF-8 has been identified as a highly active, selective and stable catalyst in the selective catalytic reduction of PNP. The Fe-N-C catalyst is for the first time applied in PNP reduction and found to present 100% conversion and 100% product selectivity. A mechanism investigation has been carried out to conclude that in the PNP reduction on Fe-N-C, water acts as the main hydrogen provider and sodium borohydride is the electron donator. Furthermore, the Fe-N-C catalyst works well when it is applied in PNP degradation in real water samples, which further indicates its applicability in industrial wastewater treatment. This work offers a simple and useful strategy to design robust catalysts for the selective catalytic reduction of nitroaromatics.