4-nitrophenol In Water Research Articles

Electron transfer enhanced catalytic activity of nitrogen doped reduced graphene oxide supported CuCo2O4 towards the fast reduction of 4-nitrophenol in water

There has been a growing interest in the design and development of graphene based composite materials with superior performances for environmental catalytic applications. But in most of the studies the synthesis conditions require elevated temperatures and expensive working setups (high temperature furnaces, autoclaves, inert atmosphere conditions etc.). In this reported work, the nitrogen doped reduced graphene oxide supported CuCo2O4 (NG/CuCo2O4) composites were prepared through a simple one pot synthesis method under mild conditions (∼95 °C and air atmosphere) and successfully employed as catalysts for the reduction of toxic 4-nitrophenol (4NP). The characterization results revealed the successful formation of NG/CuCo2O4 composites with a possible charge transfer interaction between nitrogen doped reduced graphene oxide support of CuCo2O4. The NG/CuCo2O4 hybrids exhibited robust catalytic activity in 4NP reduction with an activity factor of 261.5 min−1 g−1. A 4NP conversion percentage which is as high as 99.5% was achieved within 11 min using the NG/CuCo2O4 catalyst. The detailed kinetic analysis confirmed the Langmuir-Hinshelwood model for the NG/CuCo2O4 catalysed 4NP reduction. The nitrogen doped reduced graphene oxide support modified the electronic levels of CuCo2O4 nanoparticles through electron transfer interactions and enhanced the catalytic activity of CuCo2O4 in NG/CuCo2O4 through improved adsorption of reactant ions and effective generation of active hydrogen species. The good reusability and stability along with profound activity of NG/CuCo2O4 catalyst makes it a promising material for wide scale catalytic applications.

Highly Robust Alginate-based Magnetic Nanosorbents of Pd Catalysts for the 4-Nitrophenol Reduction

This work presents the synthesis of alginate-coated magnetite nanoparticle (MNP) containing amino-enriched moieties for the immobilization of palladium (Pd), and its use as a recyclable catalyst for the reduction of 4-nitrophenol (4NP) in water. The alginate grafted onto the surface of MNP contained carboxylate anions that served as coordination sites for Pd. Additionally, the incorporation of amino-enriched components, such as poly(vinyl amine) (PVAm) and 2-(dimethyl amino)ethyl methacrylate (DMAEMA), onto the alginate-coated MNPs resulted in additional interactions, including the formation of carboxylate-ammonium salts. In this study, the influence of these amino groups on the efficiency of Pd immobilization, catalytic activity and reusability of nanosorbents for 4NP reduction was investigated. The existence of Pd in the nanosorbents was detected by inductively coupled plasma atomic emission spectroscopy, transmission electron microscopy, and energy-dispersive X-ray techniques. The average size of MNPs was approximately 12.3 ± 2.9 nm, and for Pd, it was about 3.9 ± 0.8 nm. It was found that the incorporation of these amino-enriched moieties into the particles significantly enhanced the catalytic activity of the nanosorbents. Notably, MNP containing extended DMAEMA units exhibited excellent tolerance to 4NP reduction, with an insignificant loss of catalytic performance even after 20 consecutive reuses, maintaining a conversion of over 98 %. HIGHLIGHTS Synthesis of alginate-based magnetite nanoparticle for the immobilization of Pd and its use as a catalyst for the reduction of 4-nitrophenol in water were presented The carboxylate groups in alginate provided the coordinating sites for Pd immobilization and improved the particle dispersibility in water The incorporation of amino-enriched components to the particle reduced the degree of Pd aggregation on the particle surface The catalysts had high catalytic performance for the reduction of 4-nitrophenol in water and exhibited highly robust properties with excellent reusability for up to 20 cycles with insignificant changes in their performance GRAPHICAL ABSTRACT

Metal oxide-biochar supported recyclable catalysts: A feasible solution for the reduction of 4-nitrophenol in water

MOx-biochar (Mox = Cu, Co, Mn or Ni oxides) supported materials were prepared, characterised and tested in the reduction of 4-nitrophenol to 4-aminophenol employing sodium borohydride as reducing agent. The catalyst/reducing agent optimal ratio was determined for the copper oxide-based catalysts obtained by wet impregnation (BC1CuOx) and by an alkaline method followed by a hydrothermal treatment (BC2CuOx), as they proved to be the most active ones. The total reduction of 4NP was reached at 2.1 and 0.80 min for BC1CuOx and BC2CuOx, respectively. BC2CuOx could be reused up to five times in consecutive runs without any treatment between the cycles.

Binuclear Mn(III) and Fe(III) porphyrin nanostructured materials in catalytic reduction of 4-nitrophenol

Biomimetic reduction reactions may disclose alternatives to the use of noble metals or transition metals of late series that are expensive, toxic, or scarcer. In this work, binary nanostructured materials carrying positive and negative iron (III) and manganese (III) porphyrins were prepared by ionic self-assembly, in a simple and eco-sustainable way, and characterized by SEM, XRD, UV–vis and XPS. The materials were evaluated as catalysts in the reduction of 4-nitrophenol in water, using NaBH4 as a reductant. The effect of the crystallite structures, of the nature of the dual metal ion centers and of solar light, in the catalyst activity were also evaluated. The highest activity was observed for a heterobimetallic [Mn/Fe] material carrying Fe(III) and Mn(III) porphyrins as positive and negative tectons, respectively, leading to complete conversion of the 4-nitrophenol in 3 min under simulated solar light, and the results evidence a synergy between the two metal centers. This material was reused in successive catalytic cycles until the 7th cycle.

Carboxymethyl cellulose/polyamidoamine hydrogel loaded with nano-Ag particles as recoverable efficient catalyst for reduction of 4-nitrophenol in water

Carboxymethyl cellulose/polyamidoamine hydrogel loaded with nano-Ag particles as recoverable efficient catalyst for reduction of 4-nitrophenol in water

Yolk-shell structured molybdenum disulfide nanospheres as highly enhanced electrocatalyst for electrochemical sensing of hazardous 4-nitrophenol in water

Nanoscale materials are of great interest with functional improvement to develop prominent sensors with high sensitivity and analytical beneficial output signals, which could help emerging environmental pollutants detection in daily life. Transition metal dichalcogenide (TMD)-based electrode materials are of significant interest for environmentally hazardous 4-nitrophenol (4-NP) detection that holds the achievable advantages with low-cost effect for the efficient sensing display on electrochemical method. Herein, we report a hydrothermal approach for yolk-shell structured molybdenum disulfide nanospheres (MoS2 NS) preparation and utilized as a highly active and stable electrode material towards the environmentally hazardous 4-NP detection in tap and river water. The developed sensor results reveal that yolk-shell MoS2 NS modified GCE holds a low limit-of-detection (LOD, 2.9 nM) and an exceptional sensitivity (1.2704 µA µM−1. cm−2) with good selectivity and cycle stability. Additionally, the developed sensor holds good sensing ability in real-time applicability in tap and river water individuals with satisfying outcomes. It is revealing that the yolk-shell MoS2 NS can implement for hazardous environmental pollutants monitoring.

Synthesis and Investigation of Biological Activity of New Oxazinoazepines: Application of Fe3O4/CuO/ZnO@MWCNT Magnetic Nanocomposite in Reduction of 4-Nitrophenol in Water

In this study, oxazinoazepine derivatives were synthesized in high yields using multicomponent reactions of aniline, oxalylchloride, alkyl bromides, activated acetylenic compounds, ethyl glycinate, and methyl epoxide in the presence of Fe3O4/CuO/ZnO@MWCNT as a high-performance catalyst in water at room temperature. The Fe3O4/CuO/ZnO@MWCNT was synthesized using Petasites hybridus rhizome water extract as a green media and moderate base. Also, the catalytic activity of the green synthesized Fe3O4/CuO/ZnO@MWCNT magnetic nanocomposits (MNCs) was evaluated in the reduction of organic pollutants such as 4-nitrophenol (4-NP) in water at mild conditions. The results indicated that the biosynthesized NCs have very high and effective catalytic activity for organic pollutants within few seconds. Investigation of antioxidant ability of synthesized compounds using radical trapping of diphenyl-picrylhydrazine (DPPH) and ferric reduction power experiment is another purpose in this research. Also, the antimicrobial activity of some synthesized compounds was proved by employing the disk diffusion test on Gram-positive and Gram-negative bacteria. This procedure has some benefits such as short reaction time, product with excellent yields, simple catalyst, and products separation.

Selective recovery of gold from e-waste with 3D hierarchical porous amidoximated fabrics and its application in the reduction of 4-nitrophenol

Recycling gold from waste provides an alternative path to meet the increasing global gold consumption, and gold catalysts account for a considerable portion of this recycling effort. In this study, amidoximated fabrics (AO-NWF) were fabricated with pre-irradiation graft polymerization method. Afterwards, we used an Intel Pentium CPU as a gold source and employed an integrated strategy for the in-situ fabrication and stabilization of gold nanoparticles (AuNPs) on 3D hierarchical porous amidoxime fabrics (Au@AO-NWF) to catalyze the reduction of 4-nitrophenol in water. Au@AO-NWF showed remarkable and stable catalytic performance, recording a maximum reaction rate constant of 0.5994 min−1. Finally, the recovered gold could be further used in electronic equipment. Thus, a green, closed-loop utilization of gold was accomplished, which could help reduce electronic waste (e-waste) pollution, superfluous sources, and energy consumption to protect the environment. As a candidate for gold adsorption, the ability of AO-NWF to extract gold from water was also evaluated in detail.

Sensitive Detection of 4-Nitrophenol in Water Based on Functionalized Pyridine Diketopyrrolopyrrole-Graphene Oxide Electrochemical Sensor

Sensitive Detection of 4-Nitrophenol in Water Based on Functionalized Pyridine Diketopyrrolopyrrole-Graphene Oxide Electrochemical Sensor

Nanoparticles-Encapsulation Poly(Ionic Liquid) Hydrogel as Super-Tough, Highly Active and Recyclable Catalyst Carrier in Reduction of 4-Nitrophenol in Water

Nanoparticles-Encapsulation Poly(Ionic Liquid) Hydrogel as Super-Tough, Highly Active and Recyclable Catalyst Carrier in Reduction of 4-Nitrophenol in Water

Thermal-switchable sensor based on palladium-graphene composite and poly(N-isopropylacrylamide) for electrochemical detection of 4-nitrophenol

Improving dispersion of metal nanoparticles on graphene sheet still faces great challenges in fabrication of metal-graphene composite. The study reports one way for synthesis of palladium-graphene composite with histidine-functionalized graphene quantum dot (His-GQD) as linker and semiconductor. The resulting composite offers a three-dimensional architecture. Small Pd nanoparticles are uniformly dispersed on graphene sheets. The intimate contacts of His-GQD with graphene and Pd nanoparticle create the Schottky heterojunction and leads to an improved catalytic activity. Thermal-switchable sensor based on the Pd-His-GQD-G and poly(N-isopropylacrylamide) (PNIPAM) exhibits better sensitivity, selectivity and long-term stability for electrochemical detection of 4-nitrophenol compared with the reported sensors. The differential pulse voltammetric current linearly increases with the increase of 4-nitrophenol in the range of 0.5–250 μM with detection limit is 0.10 μΜ (S/N = 3). The proposed analytical method has been successfully applied in detection of 4-nitrophenol in water.

Green Synthesis of Ag-Au Bimetallic Nanocomposites Using Waste Tea Leaves Extract for Degradation Congo Red and 4-Nitrophenol

A sustainable supply of pure water is a great challenge in most developing and third-world countries. Nanomaterial-based technology offers technological development for wastewater purification. Nanocatalysis hydrogenation of nitroarene and dye molecules is a hot model in many research fields. Herein, we report eco-friendly and facile technology to synthesize Ag-Au bimetallic nanocomposites. The synthesized nanocomposites are characterized by ultraviolet–visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy and high-resolution transmission electron microscopy. The synthesized nanocomposite can efficiently degrade Congo red and 4-nitrophenol in water and in the presence of sodium borohydride. The results show that it degrades Congo red and 4-nitrophenol entirely within 6 and 7 min, respectively. These results could be useful for the green synthesis of Ag-Au bimetallic nanocomposites and help to remove organic dye molecules and nitroaromatics from wastewater.

Efficient photocatalytic generation of hydrogen by twin Zn0.5Cd0.5S nanorods decorated with noble metal-free co-catalyst and reduction of 4-nitrophenol in water

The development of heterostructure photocatalysts composed of homo- or hetero-junction is a favorable approach for efficient visible-light-assisted photocatalytic conversion of solar energy into clean fuel, H2. Further, for large-scale production of hydrogen, the use of cost-effective earth-abundant photocatalysts is highly desirable. Consequently, herein we report the synthesis of heterostructure photocatalysts composed of twin Zn0.5Cd0.5S nanorods (NRs) decorated with noble-metal-free co-catalyst, Ni(OH)2 nanoparticles (NPs) for efficient visible-light-assisted H2 generation from water. Remarkably, the optimized heterostructure, Zn0.5Cd0.5S/7wt%Ni(OH)2 (CN-7) showed excellent catalytic activity with an H2 generation rate of 139 mmol g-1 h−1 which was found to be about 1.5 and 9.4 times higher than those of pristine Zn0.5Cd0.5S NRs (C-1) and CdS/7wt%Ni(OH)2, respectively. Moreover, the photocatalyst is recyclable for several cycles and can work in both acidic and basic conditions. A probable mechanism of the H2 generation by Zn0.5Cd0.5S/Ni(OH)2 heterojunction has also been discussed. Interestingly, the photocatalytic activity was extended for efficient reduction of 4-nitrophenol from water using the in situ generated hydrogen as a reducing agent. Overall, this is a unique demonstration wherein water a green solvent is utilized as a source of reducing agent for visible-light-driven reduction of the environmental pollutants from water.

The construction of a novel luminescent lanthanide framework for the selective sensing of Cu2+ and 4-nitrophenol in water.

It is challenging to develop highly stable lanthanide luminescent sensors for detecting heavy metal ions and nitroaromatics in view of the human health and environmental security. To this end, two water stable Ln-MOFs with the chemical constitution of {[Ln(HL)]·3DMF·3H2O}n (Ln = Eu, LZG-Eu and Ln = Tb, LZG-Tb) have been developed solvothermally using a multidentate ligand (H4L) with the central phenyl backbone bisubstituted by 2,6-pyridine-dicarboxylic acid at the para-position, H4L = 1,4-bis(2',2'',6',6''-tetracarboxy-1,4':4,4''-pyridyl)benzene. Single crystal analysis demonstrates that two novel Ln-MOFs feature 4,4,4-connected nets with an unprecedented topology symbol of {42·6·83}2{42·62·82}{42·84} and contain two kinds of one-dimensional channels. Powder X-ray diffraction as well as the luminescence determination results indicate that they retain their crystallinity and structural integrity in harsh acidic and basic conditions with pH in the range of 4-11. Moreover, they are highly luminescent, which makes them excellent chemical sensors for detecting Cu2+ and 4-NP (4-nitrophenol) with high selectivity and sensitivity in aqueous media such as deionized water, tap water, and river water based on distinct quenching effects. To the best of our knowledge, their detection limits are lower than those documented so far. In addition, the quenching efficiency of 4-NP was retained in the presence of interfering ions even after the compounds were used for five cycles, which makes them attractive, reliable, visual, and recyclable luminescent Ln-MOF sensor materials for 4-NP. The recognition mechanism for Cu2+ could be attributed to the dissociation of the main framework induced by Cu2+ and the subsequent formation of a Cu2+ coordination species and that for 4-NP is considered to be multi-quenching mechanisms dominated by competition absorption.

Alginate modified magnetic nanoparticles to immobilization of gold nanoparticles as an efficient magnetic nanocatalyst for reduction of 4-nitrophenol in water

This article displays synthesis of gold nanoparticles (Au NPs) decorated on sodium alginate (Alg) covered magnetite (Fe3O4@Alg-AuNPs) nanocomposite. Sodium alginate shell as a natural anionic polysaccharide on Fe3O4 microparticles core acted as a stabilizing agent for immobilization of Au NPs. Its catalytic performance was tested in the reduction of 4-nitrophenol to 4-aminophenol. The structural features of the synthesized nanocatalyst were investigated by Fourier-transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Transmission electron microscopy (TEM), Energy Dispersive X-Ray Analysis (EDX), and Vibrating-sample magnetometer (VSM) studies. The catalytic activity of the material in the reduction process was quantitatively monitored using Ultraviolet–visible (UV–Vis) spectroscopy and it resulted excellent yields (99%) at short reaction time (1.5–4 min) in aqueous media at room temperature using very low catalyst load (1–3 mg). The kinetics study was also performed which afforded a good rate constant. Additionally, the catalyst showed high reproducibility as was easily retrievable and recoverable without noticeable loss in its catalytic activity.

Preparation of PdNPs doped chitosan-based composite hydrogels as highly efficient catalysts for reduction of 4-nitrophenol

The development of functional hydrogel materials for applications in catalysis has attracted great research interest, especially in aqueous phase catalysis. However, preparation of new structural hydrogel catalysts with enhanced catalytic activity still remains a challenge. In this study, a series of Pd nanoparticles (PdNPs) doped chitosan (CS)-based composite hydrogels were successfully prepared by adding graphene oxide (GO), carbon nanotubes (CNTs) and layered double hydrotalcites (LDHs) to CS hydrogel with glutaraldehyde as a cross-linking agent and in situ growing PdNPs. The structure and morphology analysis indicated that chitosan-based composite hydrogels could be used as carriers to load PdNPs and effectively prevent the agglomeration of PdNPs. Subsequently, 4-nitrophenol (4-NP) catalytic reaction was used as a typical model to evaluate catalytic performances of chitosan (CS)-based composite hydrogel catalysts. The obtained chitosan-based composite hydrogel catalysts exhibited better catalytic activity than that of PdNPs doped CS hydrogel catalyst (CS-PdNPs) and reusability for the reduction of 4-nitrophenol in water. The catalytic process conformed to the pseudo-first-order kinetic equation. Moreover, chitosan-based composite hydrogel catalysts containing CNTs had the best catalytic performance since the particle size of PdNPs was the smallest among three kinds of chitosan-based composite hydrogel catalysts. This work provides new ideas for the preparation of stable and efficient precious metal nanoparticle catalysts for applications in aqueous phase catalysis.

A novel strategy to construct supported silver nanocomposite as an ultra-high efficient catalyst

While supported-Ag nanocomposites play a pivotal role in heterogeneous catalytic reactions, the synthesis of small-sized (＜10 nm), uniformly distributed supported-Ag catalysts by environmentally friendly methods remains a challenging task. In this work, we first introduced –SO3Ag groups on macroporous resin (MR) surface via sulfonation, neutralization and ion-exchange reactions, and prepared the small-sized and evenly distributed Ag nanoparticles at gas/solid interface by reduction in gaseous vanillin atmosphere. The mild reaction conditions are favorable for the formation of atomic step-rich Ag nanostructure, which are beneficial to the catalytic activity of Ag/MR. Simultaneously, the ion-exchange functional group plays an important role in tuning the chemical environment of the silver catalyst. As a trusted model reaction, the reduction of 4-nitrophenol in water was used to test the catalytic activity. Ag/MR exhibits ultra-high catalytic activities, and its turnover frequency is orders of magnitude higher than those reported in literature. The pull-push catalytic mechanism ascribed to SO3− groups was first presented. This work presents a powerful and general strategy for the creation of highly efficient supported metal nanocatalysts.

Electrocatalytic Reduction and Detection of 4-Nitrophenol in Water at Free-Standing Cu Nanowire Electrode

Electrocatalytic Reduction and Detection of 4-Nitrophenol in Water at Free-Standing Cu Nanowire Electrode

Gold nanoparticles supported on mesostructured oxides for the enhanced catalytic reduction of 4-nitrophenol in water

In this work, Au nanoparticles supported on aluminum oxide (Au/ANT) and titanate (Au/TNT) nanotubes were synthesized for their use as catalysts in the reduction of 4-nitrophenol to produce 4-aminophenol with NaBH4 as the reducing agent. The catalysts were prepared with a 0.5 % metal loading employing the nanotube supports modified with 3-aminopropyl-trimethoxysilane (APTMS) to provide plentiful anchoring sites to trap the Au nanoparticles and prevent their agglomeration. All materials were characterized using a range of analytical techniques, and it was found that Au zero-valent nanoparticles were homogenously supported on the inner/outer surfaces of the nanotubular-structured carriers. Both catalytic systems were highly active and selective in the reduction of 4-nitrophenol, giving TOF values of 20,561 and 19,560 h−1 for Au/TNT and Au/ANT, respectively. The excellent catalytic activity was attributed to the highly dispersed Au clusters on the support surfaces through enhanced functionalization with APTMS, and the confinement effect of the nanotubular carriers. Furthermore, Au/TNT exhibited a high operational stability for the reduction of 4-nitrophenol reaching 10 catalytic cycles with only a moderate decrease in the conversion level after the seventh cycle, which was attributed to a degree of metal leaching. Finally, the catalytic reduction performance of the Au/TNT catalyst was tested in different nitroarene-substituted pharmaceuticals, and revealed a high activity (>99 % after 60 min of reaction) and selectivity toward production of the desired substituted anilines, thereby highlighting the potential of this catalyst for application in these processes.

Copper hexacyanoferrate nanocrystal as a highly efficient non-noble metal catalyst for reduction of 4-nitrophenol in water

As Prussian Blue analogues (PBAs) represent one of the most classical families of coordination compounds and exhibit versatile catalytic activities, PBAs have been considered as useful heterogeneous catalysts for reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). Nevertheless, while Cu has been a well-proven transition metal for 4-NP reduction, especially, due to their ability to attain pronounced conversions of reactants under mild conditions, environmental friendliness and great stability. Nevertheless, while Cu has been a well-proven transition metal for 4-NP reduction, Cu-based PBA has never been developed and thoroughly investigated for 4-NP reduction. Thus, in this study, copper hexacyanoferrate, CuII3[Fe(CN)6]2 (CuFeCN) is particularly synthesized and proposed for the first time as a catalyst for reduction of 4-NP in the presence of NaBH4. CuFeCN exhibits a very high catalytic activity towards reduction of 4-NP to 4-AP with 100% conversion within 4 min. The activity factor (AF) at room temperature, 8057.14 s−1 g−1, is between 1 and 2 orders higher than all other MFeCN Prussian blue analogues (M = Co, Fe, Ni, Zn, and Mn). In addition, CuFeCN shows excellent reusability to achieve 100% conversion of 4-NP to 4-AP with highly stable rate constants over successive 7 cycles. The activation energy (Ea) and turn over frequency (TOF) for the reduction of 4-NP to 4-AP catalyzed by CuFeCN system are determined as 24.6 kJ mol−1 and 36.93 min−1, respectively, which are both significantly more superior than most of reported catalysts in literatures. These advantageous properties make CuFeCN ideal to be developed into a promising catalyst for elimination of nitroaromatic contaminants in water.