Presence Of NaBH4 Research Articles

Phyto-constructed copper urchin-like nanoflakes to facilitate the catalytic elimination of organic pollutants

In this context, Copper (Cu) nanoparticles were advanced the use of a sustainable technique for the synthesis addressing Morindacitrafolia leaf (MCL) extract. The fabricated of catalyst were technically examined by using TEM, XRD, SEM, EDAX, AFM, UV–Vis spectrophotometer, and FT-IR research were used to evaluate the topological, crystallographic, and structural features. The produced M@Cu Nano catalyst’s catalytic ability was examined for an interaction involving methyl orange dye under the presence of NaBH4 as an inhibiting agent. In an effort to achieve optimal reduced chemical conditions, the implications of the catalytic dosage, pH, and dye initial quantity was examined. The M@Cu Nano trigger, once developed, effectively eliminated 99.9 % of the harmful organic dyesof methyl orange, suggesting it may have utility towards the treatment of debris and polluted water. This investigation demonstrates the inexperienced synthesis of Cu Nanoparticles and its programs in environmental remediation.

Insight to the Catalytic Activity of Atomically Precise Ag4Ni2 Nanoclusters on Silicon Carbide for Nitroarene Reduction.

Atomically precise Ag4Ni2 nanoclusters with 2,4-dimethylbenzenethiol as the ligands were synthesized and characterized as a cocatalyst of SiC for the selective hydrogenation of nitroarenes to arylamine in the presence of NaBH4. The obtained Ag4Ni2/SiC samples exhibited extraordinary catalytic activity, and a self-accelerated catalytic process was observed with the reduction of nitrophenol to aminophenol as the model reaction. Experimental comparison between the Ag4Ni2/SiC samples before and after the catalysis showed that the transformation of Ag4Ni2 clusters to polydisperse Ag particles as well as amorphous NiOx on the surface of SiC in the catalysis was the key to their high activity. AIMD calculations revealed that the transformation of Ag4Ni2 was driven by the presence of multiple hydrides on the cluster, which induced the detachment of the thiol ligand of the nanoclusters.

Enhanced photocatalytic degradation of organic pollutants by green-synthesized gold nanoparticles using polysaccharide for environmental remediation

The recent rise in textile dye wastewater discharge into the environment has detrimental effects on living organisms and human health. The present study reports a facile approach to green-synthesized AuNPs employing sesbania gum for catalytic and photocatalytic degradation of organic pollutants. The obtained AuNPs were characterized by various techniques such as UV–vis, FT-IR, SEM, TEM, AFM, zeta potential, LC-MS, and XPS. The XRD patterns revealed a highly crystalline and face-centered cubic structure. XPS and EDX analysis defined the chemical composition and product purity of SBG-AuNPs. Photocatalytic degradation of hazardous dyes congo red and safranin-O using SBG-AuNPs showed a rapid decomposition rate with 94.69 % under visible light irradiation. The effect of pH, dye concentration, and catalyst dose on photodegradation and recyclability was also studied. The kinetic plots were used to calculate the rate constant, showing a pseudo-first-order reaction. Scavenger trap experiments confirmed the role of h+ and superoxide(.O2−) as active species, and LCMS analysis was used to identify the degradation intermediates. The catalytic reduction of SBG–AuNPs was studied for brilliant green (BG) and methylene blue (MB) in the presence of NaBH4, resulting the degradation efficiency of 90.37 % and 84.52 %, respectively. This study presents an innovative approach for designing highly efficient photocatalysts for environmental remediation and wastewater treatment from textile dyes.

Catalytic Performance in Nitroarene Reduction of Nanocatalyst Based on Noble Metal Nanoparticles Supported on Polymer/s-Layer Protein Hybrids.

We present a novel bionanocatalyst fabricated by the adsorption-reduction of metal ions on a polyurethane/S-layer protein biotemplate. The bioinspired support was obtained by the adsorption of S-layer proteins (isolated from Lentilactobacillus kefiri) on polyurethane particles. Silver and platinum nanoparticles were well-loaded on the surface of the support after the combination with metallic salts and reduction with H2 at room temperature. Transmission electron microscopy analysis revealed the strawberry-like morphology of the bionanocatalysts with a particle size, dn, of 2.39 nm for platinum and 9.60 nm for silver. Both systems catalyzed the hydrogenation of p-nitrophenol to p-aminophenol with high efficiency in water at mild conditions in the presence of NaBH4. Three different amounts of bionanocatalyst were tested, and in all cases, conversions between 97 and 99% were observed. The catalysts displayed excellent recyclability over ten cycles, and no extensive damage in their nanostructure was noted after them. The bionanocatalysts were stable during their production, storage, and use, thanks to the fact that the biosupport provides an effective driving force in the formation and stabilization of the metallic nanoparticles. The successful bioinspired production strategy and the good catalytic ability of the systems are encouraging in the search for nontoxic, simple, clean, and eco-friendly procedures for the synthesis and exploitation of nanostructures.

Reduction of Methylene Blue Using Silica Nanoparticles Obtained from Waste ZrC

AbstractThe study conducted an extraction of pure amorphous nano‐silica (SiO2 NP) from waste product at the ZrC factory. Various techniques such as TEM, SEM‐EDX, ICP, XRD, FTIR, BET, and DLS were utilized to synthesize and characterize the silica nanoparticle. The results showed successful production of pure amorphous silica, with no discernible difference in purity percentage between samples prepared with or without acidic pre‐treatment. It was found that the leaching temperature, process time, and reactant ratio all played a role in the production of nano‐silica. The ideal leaching temperature was determined to be 368 K, with an optimal process time of 2 h. The weight ratio of WPZF/NaOH that yielded the highest percentage of silica extraction was 9 : 10. Additionally, at pH 7, the nano‐silica exhibited the best specific surface area (BET) of 472.51 m2/g. The average size of the spherical nano‐silica, as determined by DLS, was approximately 38 nm. Furthermore, the produced nano‐silica was found to be an effective catalyst for the treatment of methylene blue (MB). MB could be degraded by more than 99 % of the initial concertation (10 mg/L) in the presence of NaBH4 within 16 min and rate constant of the catalytic reduction achieved as 0.134 min−1. These findings demonstrate the potential of amorphous nano‐silica as a valuable resource in various applications.

Schiff Base Functionalized Cellulose: Towards Strong Support-Cobalt Nanoparticles Interactions for High Catalytic Performances.

A new hybrid catalyst consisting of cobalt nanoparticles immobilized onto cellulose was developed. The cellulosic matrix is derived from date palm biomass waste, which was oxidized by sodium periodate to yield dialdehyde and was further derivatized by grafting orthoaminophenol as a metal ion complexing agent. The new hybrid catalyst was characterized by FT-IR, solid-state NMR, XRD, SEM, TEM, ICP, and XPS. The catalytic potential of the nanocatalyst was then evaluated in the catalytic hydrogenation of 4-nitrophenol to 4-aminophenol under mild experimental conditions in aqueous medium in the presence of NaBH4 at room temperature. The reaction achieved complete conversion within a short period of 7 min. The rate constant was calculated to be K = 8.7 × 10-3 s-1. The catalyst was recycled for eight cycles. Furthermore, we explored the application of the same catalyst for the hydrogenation of cinnamaldehyde using dihydrogen under different reaction conditions. The results obtained were highly promising, exhibiting both high conversion and excellent selectivity in cinnamyl alcohol.

Exploring a surface-capping role of carboxymethyl cellulose for the synthesis of silver nanoparticles via the induction period in a catalytic hydrogenation

The present study reported a dual role as a reducing agent and a stabilizer of carboxymethyl cellulose (CMC), a natural origin biopolymer, for the synthesis of silver nanoparticles (AgNPs) via a chemical reduction method. The operating parameters were optimized and established involving pH, reaction time, reaction temperature, AgNO3 molar concentration, CMC/Ag molar ratio. The formation of monodisperse AgNPs in the assistance of a CMC surface-capping agent thanks to an electrostatic stabilization effect was evidenced by ultraviolet-visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and transmission electron microscope (TEM). The aqueous solution consisting of AgNPs in roughly spherical shape with a mean particle size of 24.3 nm was stable in ambient condition at least 2 months. The role of CMC as a surface-capping agent was also explored via the catalytic hydrogenation of methyl orange (MO) towards aromatic amines in the presence of NaBH4 at room temperature, revealing the induction period of 12 min before accelerating reaction rate in the next 18 min. At room temperature, such a catalytic hydrogenation of MO in water obeyed the pseudo first-order kinetic model with a rate constant of 0.2435 min−1 using 2.5 ppm CMC-capped AgNPs catalyst, and the reuse performance was remained in 5 consecutive cycles. To sum up, the present work shed light on a surface-capping role of carboxymethyl cellulose for the synthesis of silver nanoparticles by both physicochemical and catalytic studies.

Polyurethane‐based nanocomposite for catalytic reduction of toxic dyes

AbstractIn this work, we prepared AuNPs loaded polyurethane‐sodium alginate (Au‐PU‐ALg) composite polymers by casting and in‐situ reduction method. Successful fabrication of AuNPs was confirmed by UV–visible, Fourior transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), field emission scanning elcetron microscopy (FESEM), and energy dispersive X‐ray (EDX) analysis along with the change in color of the suspension from yellow to dark purple. Thermo‐gravimetric analysis (TGA) also confirmed the loading of 7.44 % AuNPs of total nanocomposite contents. The catalytic activity of Au‐PU‐ALg nanocomposites was checked by reducing Rhodamine B (RhB) as a model reaction. It was seen that reduction of RhB was successfully done in the presence of NaBH4 and Au‐PU‐ALg nanocomposite in just 8 min with value of kapp found as 0.648 min−1. While the value of kapp for RhB reduction was found as 0.0008, 0.00221, and 0.0008 min−1 in the presence of catalyst, NaBH4 and polymer gel particles, respectively. Thus results show that the value of kapp for the reduction of RhB in the presence of NaBH4 and catalyst was found high as compared to the controlled reactions. Complex mixture of dyes such as RhB, crystal violet (CV), Congo red (CR), and dyes polluted industrial wastewater was become colorless in 10 and 3 min, respectively on mixing with catalyst and reducing agent. It was also observed that reduction of RhB followed pseudo first order kinetic model and Langmuir Hinshelwood mechanism.

A practical approach for reduction 4-nitrophenol to 4-aminophenol using CoMnaOb (a= 2, and b= 4)/MWCNT nanocatalyst

In recent decades, 4-nitrophenol has become one of the most dangerous substances due to its harmful effects on the environment and the human body. Therefore, the reduction of 4-nitrophenol is necessary to reduce health and environmental impacts. This research presented a novel method for preparing CoMnaOb (a= 2, and b= 4)/MWCNT nanocatalyst to reduce 4-nitrophenol in the presence of NaBH4. However, the high electronic conductivity of MWCNT and the active sites of cobalt and manganese in the nanocatalyst surface exhibited a critical role in nanocatalyst activation for the reduction of 4-nitrophenol in the presence of NaBH4. The prepared nanocatalyst has advantages, including easy fabrication, excellent performance, recyclability, and cost-effectiveness, distinguishing it from other nanocatalysts. The fabricated nanocatalyst showed the highest reduction rate of 4-nitrophenol (97.8%) within 10 min. The results displayed that the 4-nitrophenol reduction in the presence of CoMnaOb/MWCNT was better than alone- CoMnaOb, corroborating the synergistic impact of MWCNT with metal oxides. Meanwhile, the nanocatalyst was recycled during five runs to reduce 4-nitrophenol without decreasing catalyst activity. The present research can be an excellent example of the design of nanocatalysts based on metal oxides with carbon materials to reduce 4-nitrophenol to 4-aminophenol.

Biosynthesis, characterization and study of the application of silver nanoparticle for 4-nitrophenol reduction, and antimicrobial activities

Silver nanoparticles (AgNPs) were synthesized from Vigna unguiculata (L) Walp extracted leaves, and characterized. The UV–Visible spectrum showed a peak between 411 and 415 nm at the Plasmon absorbance of the AgNPs. TEM showed that the size of AgNPs ranged from 5 to 13 nm. It was spherical with an average size of 11.08 nm. The size of AgNPs was 7 ± 6 nm and disperse in water. The AgNPs effectively reduced 4-Nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of NaBH4. The AgNPs exhibited a strong antioxidant and antibacterial activity against Gram-negative bacteria: Escherichia coli (E. coli) and Klebsiella pneumonia and Gram-positive: Bacillus pumilus and Staphylococcus aureus. The average zones of inhibition of AgNPs were: 29 mm for Staphylococcus aureus, 23 mm for Bacillus pumilus, 17 mm for Klebsiella pneumonia and 15 mm for Escherichia coli (E. coli). Thus, AgNPs has exhibted good antibacterial activity compared to antibiotics drug and 4-NP reduction.

Nickel doped ZIF-67 catalyst for the catalytic reduction of environmental pollutant, 4-nitrophenol

BackgroundBimetallic synthesis is a promising method to improve the properties of zeolitic imidazole frameworks such as ZIF-67 for catalytic applications. The study aimed to synthesize highly efficient and stable catalyst Ni-doped ZIF-67 by bimetallic facile synthesis of ZIF-67 at room conditions and to use for the catalytic reduction reaction of 4-nitrophenol (4-NP), which is a highly toxic component for the environment, in the presence of NaBH4 as reducing agent. MethodsDifferent amounts of nickel were added during the synthesis of ZIF-67. The structure of catalysts was elucidated using different characterization methods (SEM, FTIR, TGA, N2 adsorption, XRD, and XPS). Significant findingsNi0.3@ZIF-67 exhibited the highest reduction efficiency with excellent stability. The obtained results denoted that the catalytic activity was improved by the increasing amount of nickel and the required complete reduction time was determined as 2 min. The obtained rate constants values of reaction are 0.716 min−1, 1.156 min−1, and 1.945 min−1 according to the pseudo-first-order mechanism for 30°C, 40°C, and 50°C, respectively. Heterogeneous catalyst formed by doping Ni to ZIF-67 can be a promising way for the reduction of 4-NP to 4-AP.

Self-Healing Conjugated Microporous Polyanilines for Effective and Continuous Catalytic Detoxification of 4-Nitrophenol to 4-Aminophenol.

Detoxification of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with high efficiency and dynamic performance is challenging for a polymeric catalyst. Herein, a series of conjugated microporous polyanilines (CMPAs), capable of efficiently catalytically reducing 4-NP, were synthesized based on the Buchwald-Hartwig cross-coupling reaction mechanism. By adjusting the types of linkers and the molar ratios of linker to core, CMPAs with different Brunauer-Emmett-Teller (BET) specific surface areas and reduction degrees were obtained and used as the catalysts in reducing 4-NP. The ultrahigh catalytic reduction efficiency (K = 141.32 s-1 g-1, kapp = 0.00353 s-1) was achieved when using CMPA-3-0.7 as the catalyst (prepared with 4,4'-diaminodiphenylamine as the linker and a 0.7:1 molar ratio of linker to core). The catalytic reduction performance exhibited a strong correlation with the reduction degree and BET specific surface area of CMPAs. Furthermore, they also exhibit excellent cycling stability and dynamic performance. The coexistence of a microporous structure and high BET specific surface area endowed CMPAs with an increased number of catalytic active centers. The reversible redox transformation of CMPAs in the presence of NaBH4 and air enabled self-healing (the oxidation units in CMPAs were reduced to reduction units by NaBH4, and the newly generated reduction unit in CMPAs was subsequently oxidized to its original state by the O2 in the air), leading to the reduction reaction of 4-NP proceeded continuously and stably. The aforementioned factors resulted in the high efficiency of CMPAs for reducing 4-NP to 4-AP, enhancing the practical application prospects of CMPAs in the detoxification of 4-NP wastewater.

Interfacing Ag2S Nanoparticles and MoS2 Nanosheets on Polypyrrole Nanotubes with Enhanced Catalytic Performance.

The tubular architecture with multiple components can bring synergistic effects to improve the enzyme-like activity of molybdenum-based nanomaterials. Here, a facile polypyrrole (PPy)-protected hydrothermal sulfidation process was implemented to engineer MoS2/Ag2S heterointerfaces encapsulated in one-dimensional (1D) PPy nanotubes with MoO3@Ag nanorods as the self-sacrificing precursor. Notably, the sulfidation treatment led to the generation of MoS2 nanosheets (NSs) and Ag2S nanoparticles (NPs) and the creation of a tubular structure with a "kill three birds with one stone" role. The Ag2S/MoS2@PPy nanotubes showed the synergistic combined effects of Ag2S NPs, MoS2 NSs, and the 1D tube-like nanostructure. Based on the synergistic effects from these multiple components and the tubular structure, Ag2S/MoS2@PPy nanocomposites were used as a colorimetric sensing platform for detecting H2O2. Moreover, the reduction of 4-nitrophenol (4-NP) revealed excellent catalytic activity in the presence of NaBH4 and Ag2S/MoS2@PPy nanocomposites. This work highlights the effects of MoS2/Ag2S heterointerfaces and the hierarchical tubular structure in catalysis, thereby providing a new avenue for reducing 4-NP and the enzyme-like catalytic field.

White LED light mediated green photoreduction of nitroarenes to anilines on bimetallic Ni/Ag@resin: In situ SERS monitoring and evaluation of plasmonic effect

Reduction of nitroarenes to anilines, a potentially important organic transformation, is classically performed in harsh conditions, which have long lasting safety issues and wastage of energy. Herein, we report an efficient hot-electron induced reduction of nitroarenes to the corresponding anilines over bimetallic Ni/Ag@resin in presence of NaBH4 under white LED light irradiation. Mechanistically, the hot electrons assisted the dimerization of 4-NTP to cis-4,4′-dimercaptoazobenzene as the active intermediate evidenced by appearance of SERS peaks at 1389 cm−1. Hot electrons having energy content above a threshold can transfer the energy effectively to the LUMOs of the reactant nitroarenes. Overall the present catalyst system constitutes one straightforward and environmentally safe approach to a class of much sought organic transformation.

Metal Organic Framework Derived Cu-Carbon Composite for the Effective Reduction of p-Nitrophenol

A Cu-carbon composite (Cu-C) was prepared via single-step carbonization of a metal-organic framework (MOF) composed of Cu2+ and 1,4-benzene dicarboxylate (BDC) and applied as a catalyst to degrade p-nitrophenol. The composite was characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM)/energy-dispersive X-ray (EDS), Fourier-transform infrared (FTIR) and X-ray photoelectron (XPS) spectroscopies. The characterization affirmed the preservation of MOF-originated CuO and metallic Cu in the carbon network. In presence of NaBH4, the Cu-C composite resulted in a complete reduction of p-nitrophenol within a few min and exhibited much higher removal rate than commercial CuO. The role of NaBH4 concentration in p-nitrophenol reduction was highlighted in the context of relevant catalytic mechanisms. The composite displayed good reusability during four consecutive cycles of p-nitrophenol reduction with only a small loss of its reactivity, signifying its potential as an alternative to noble-metal catalysts.

Rapid Plasma Electrolytic Oxidation Synthesis of Intermetallic PtBi/MgO/Mg Monolithic Catalyst for Efficient Removal of Organic Pollutants.

The intermetallic PtBi/MgO/Mg monolithic catalyst was first prepared using non-equilibrium plasma electrolytic oxidation (PEO) technology. Spherical aberration-corrected transmission electron microscope (ACTEM) observation confirms the successful synthesis of the PtBi intermetallic structure. The efficiency of PtBi/Mg/MgO catalysts in catalyzing the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of NaBH4 was demonstrated. The activity factor for the catalyst is 31.8 s-1 g-1, which is much higher than reported values. In addition, the resultant catalyst also exhibits excellent catalytic activity in the organic pollutant reaction of p-nitrobenzoic acid (p-NBA) and methyl orange (MO). Moreover, benefiting from ordered atomic structures and the half-embedded PtBi nanoparticles (NPs), the catalyst demonstrates excellent stability and reproducibility in the degradation of 4-NP. This study provides an example of a simple method for the preparation of intermetallic structures as catalysts for organic pollutant degradation.

Synthesis of silver nanoparticles using Alchemilla vulgaris and Helichrysum arenarium for methylene blue and 4-nitrophenol degradation and antibacterial applications

AbstractThis study aimed to evaluate the concept of green synthesis of metallic nanoparticles (silver nanoparticles, AgNPs) by plant extracts without using any toxic or hazardous materials. Alchemilla vulgaris (AV) and Helichrysum arenarium (HA) are used as capping and reducing agents to synthesize AgNPs (as coded AV-AgNPs and HA-AgNPs). Both synthesized AgNPs were characterized by UV–visible spectrophotometry, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and transmission electron microscope (TEM). The results of characterization exhibited that AgNPs were successfully synthesized. They are highly well-dispersed, mostly spherical shape with an average size 15–20 nm. Catalytic reduction of methylene blue (MB) and 4-nitrophenol (4-NP) was assessed using synthesized AgNPs as nano-catalysts in the presence of NaBH4. The catalytic activity of the synthesized AgNPs revealed significant results in terms of degradation of MB and 4-NP to 4-AP (4-aminophenol). The reduction reactions of MB and 4-NP happen within 6–7 min using synthesized AV-AgNPs and HA-AgNPs in the presence of NaBH4. According to the reusability analysis, synthesized AgNPs demonstrated excellent degradation performances by the more than 94% removal efficiency maintained after five reuse cycles. In addition, antibacterial activities of AgNPs were investigated against Escherichia coli (E. coli; Gram-negative bacteria) and Staphylococcus aureus (S. aureus; Gram-positive bacteria) by using quantitative well-diffusion method and the inhibition zones were determined using Mueller–Hinton agar (MHA) media. AV-AgNPs and HA-AgNPs showed strong antibacterial activities against E. coli with in inhibition zone diameters 25.5 and 25 mm, respectively. AV-AgNPs and HA-AgNPs were also extremely effective on S. aureus with high inhibition zone values of 22 and 24 mm, respectively. Finally, the fabricated silver nanoparticles could be excellent candidates for the separation of hazardous materials.

An organic-inorganic hybrid based on bicapped Keggin polyoxometalate as a heterogeneous catalyst for MB removal via Fenton-like/photo-Fenton-like degradation or reduction

An organic-inorganic hybrid polyoxometalate (POM) [CuI(phen)2]4[PMoVI8VIV6O42{CuI(phen)}2]•H5O2 (CuPMoV) was explored as heterogeneous Fenton-like catalyst for methylene blue (MB) degradation in the absence/presence of visible light at neutral pH. CuPMoV was characterized by XRD, SEM, FT-IR and UV–vis DRS techniques. The effect of initial pH, the concentrations of H2O2 and dye, and CuPMoV dosage on the degradation was evaluated. The possible mechanism for the Fenton-like/photo-Fenton-like was proposed. Under the optimum conditions, the MB degradation rates were 85.3 % (Fenton-like reaction) and 95.2 % (photo-Fenton-like reaction) in 12 min, respectively. CuPMoV also exhibited excellent catalytic performance for MB reduction in the presence of NaBH4, with the reduction rate of 98.6 % in 90 s. The pseudo-first-order rate constant of the reduction was estimated as 0.0246 s−1. The high reusability and stability of CuPMoV enabled it to undergo five cycles of usage without significant loss of catalytic activity. The multi-metal composition of CuPMoV and the bicapped Keggin unit were the root of its excellent catalytic activities. CuPMoV may be a potential candidate for the practical treatment of MB contaminated wastewater via oxidation or reduction.

Preparation and characterization of CS/PAT/ MWCNT@MgAl-LDHs nanocomposite for Cd2+ removal and 4-nitrophenol reduction.

The present study evaluated the performance of multiwalled carbon nanotube (MWCNT)@MgAl-layered double hydroxide (LDH) nanoparticles loaded on poly-2 aminothiazole (PAT)/chitosan (CS) matrix (CPML) to remove Cd2+ ions from aqueous solution. The removal efficiency of modified CS/PAT with MWCNT@MgAl-LDHs was increased significantly compared to pure CS/PAT. The influence of heavy metal ion concentration, pH, temperature, adsorbent dosage, and contact time on the adsorption was examined. The optimum conditions for the adsorption of Cd2+ ions were 25 0C with the adsorbent dosage of 0.06g and initial concentration for adsorption of the Cd2+ 100mg/L at pH = 8. The maximum adsorption capacity was measured to be 1106.19mg/g. The values of thermodynamic parameters namely Gibbs free energy (ΔG°), entropy change (ΔS°), and enthalpy change (ΔH°) indicated the feasibility, spontaneity and the endothermic nature of the adsorption process, respectively. The pseudo-second-order kinetics and the Langmuir model were selected as the best models for the adsorption process. Also, CPML nanocomposite (NC) was successfully tested for p-nitrophenol (p-NP) reduction in the presence of NaBH4. The reaction was nearly completed in 6min. The fabricated CPML-NC could be reused for three consecutive cycles.

Ag nanoparticles decorated on Co3O4‐C derived from ZIF‐67: a recyclable catalyst for highly efficient reduction of nitrophenols

AbstractSilver‐based nanostructured composites as effective and stable catalysts were successfully designed as the catalyst to reduce the nitrophenols in aqueous solution at room temperature in the presence of NaBH4. The Co3O4‐C composites with regular morphology and adjustable components derived from ZIF‐67 in an air atmosphere at various temperatures (270, 300, and 350 °C) were chosen as a favorable platform to support silver nanoparticles. The acquired silver‐based nanocatalyst (Ag/Co3O4‐C) exhibited excellent catalytic performance towards the hydrogenation of nitrophenols (2‐NP, 3‐NP, and 4‐NP). The calculated rate constant (Kapp) towards the reduction of 4‐NP followed the order: Ag/Co3O4‐C‐300 (0.70 min−1)>Ag/Co3O4‐C‐270 (0.58 min−1)>Ag/Co3O4‐C‐350 (0.46 min−1). Ag/Co3O4‐C‐300 possessed the highest catalytic activity with no induction time during the reaction. What is more, Ag/Co3O4‐C‐300 could reduce 2‐NP and 3‐NP with the rate constant of 0.936 min−1 and 0.391 min−1, respectively. The catalytic activity was higher that many other metal‐based nanocomposites. The excellent catalytic performance was mainly attributed to the abundant active sites on the surface, and the interfacial synergistic effect between Ag and Co3O4‐C, which had a potential driving force for the hydrogenation reaction. In addition, the catalyst remained active even after recirculation experiments. The Ag‐based nanocomposites can be expected to be applied in industrial applications.