scholarly journals Shape-Dependent Catalytic Activity of Gold and Bimetallic Nanoparticles in the Reduction of Methylene Blue by Sodium Borohydride

Catalysts ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1442
Author(s):  
Heike Lisa Kerstin Stephanie Stolle ◽  
Jonas Jakobus Kluitmann ◽  
Andrea Csáki ◽  
Johann Michael Köhler ◽  
Wolfgang Fritzsche
Keyword(s):  
Methylene Blue ◽  
Gold Nanoparticles ◽  
Catalytic Activity ◽  
Surface Area ◽  
Sodium Borohydride ◽  
Bimetallic Nanoparticles ◽  
Pure Gold ◽  
Gold Nanoprisms ◽  
Bimetallic Nanorods ◽  
The Impact

In this study the catalytic activity of different gold and bimetallic nanoparticle solutions towards the reduction of methylene blue by sodium borohydride as a model reaction is investigated. By utilizing differently shaped gold nanoparticles, i.e., spheres, cubes, prisms and rods as well as bimetallic gold–palladium and gold–platinum core-shell nanorods, we evaluate the effect of the catalyst surface area as available gold surface area, the shape of the nanoparticles and the impact of added secondary metals in case of bimetallic nanorods. We track the reaction by UV/Vis measurements in the range of 190–850 nm every 60 s. It is assumed that the gold nanoparticles do not only act as a unit transferring electrons from sodium borohydride towards methylene blue but can promote the electron transfer upon plasmonic excitation. By testing different particle shapes, we could indeed demonstrate an effect of the particle shape by excluding the impact of surface area and/or surface ligands. All nanoparticle solutions showed a higher methylene blue turnover than their reference, whereby gold nanoprisms exhibited 100% turnover as no further methylene blue absorption peak was detected. The reaction rate constant k was also determined and revealed overall quicker reactions when gold or bimetallic nanoparticles were added as a catalyst, and again these were highest for nanoprisms. Furthermore, when comparing gold and bimetallic nanorods, it could be shown that through the addition of the catalytically active second metal platinum or palladium, the dye turnover was accelerated and degradation rate constants were higher compared to those of pure gold nanorods. The results explore the catalytic activity of nanoparticles, and assist in exploring further catalytic applications.

Gold Nanoparticles Grafted Mesoporous Silica: A Highly Efficient and Recyclable Heterogeneous Catalyst for Reduction of 4-Nitrophenol

NANO ◽  
2016 ◽  
Vol 11 (09) ◽  
pp. 1650104 ◽  
Author(s):  
Akansha Mehta ◽  
Manu Sharma ◽  
Ashish Kumar ◽  
Soumen Basu
Keyword(s):  
Gold Nanoparticles ◽  
Catalytic Activity ◽  
Mesoporous Silica ◽  
Surface Area ◽  
Heterogeneous Catalysts ◽  
High Surface ◽  
High Surface Area ◽  
Trisodium Citrate ◽  
Pure Gold ◽  
Nitrophenol Reduction

Synthesis of gold nanoparticles dispersed uniformly on mesoporous silica (mAu/SiO2) by homogeneous deposition–precipitation (HDP) method is used as an effective catalyst for reduction of 4-nitrophenol to 4-aminophenol. Silica provides support and surface area to increase the catalytic activity of gold. X-ray photon spectroscopy revealed binding energy of Au 4[Formula: see text] ([Formula: see text]84.0[Formula: see text]eV) and Au 4[Formula: see text] ([Formula: see text]87.7[Formula: see text]eV) which support the formation of Au0 on SiO2 surface. Au/SiO2 showed Langmuir type-IV isotherms which are the characteristic features of mesoporous materials furthermore, pore size decreases with incorporation of Au NP’s on SiO2 surface. The enhancement is due to the strong interaction of Au0 with silica support. The catalytic conversion was studied by UV-Visible spectroscopy and high performance liquid chromatography (HPLC) quantification method, which shows conversion of nitro group into amino group. In addition, the catalyst was easily separated and reused. The reusability of the catalyst exhibited better reduction of the 4-nitrophenol to 4-aminophenol even after 10 consecutive cycles. In comparison to trisodium citrate capped pure gold nanoparticles mAu/SiO2 catalysts showed very good catalytic activity toward nitrophenol reduction. Here we conclude that embedment of metal catalysts like Au into high surface area support like silica is a positive step toward development of novel heterogeneous catalysts.

scholarly journals Influence of Pluronic® P123 Addition in the Synthesis of Bulk Ni Promoted MoS2 Catalyst. Application to the Selective Hydrodesulfurization of Sulfur Model Molecules Representative of FCC Gasoline

Catalysts ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 793 ◽  
Author(s):  
Valentin Hetier ◽  
Diego Pena ◽  
Alexandre Carvalho ◽  
Laurence Courthéoux ◽  
Valérie Flaud ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Intrinsic Activity ◽  
Strong Increase ◽  
Similar Amount ◽  
X Ray ◽  
Mos2 Catalysts ◽  
The Impact

A way to improve hydrotreatment processes is to enhance the intrinsic activity of Ni or Co promoted MoS2 catalysts that are commonly used in such reactions. The aim of this work was to investigate the impact of the presence of Pluronic® P123 as a structuring agent during the synthesis of Ni promoted MoS2 catalysts (named NiMoS) in water at room temperature. A series of analyses, i.e., X-ray diffraction (XRD), chemical analysis, inductively coupled plasma mass spectrometry (ICP-MS), nitrogen adsorption-desorption isotherms, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), helped in characterizing the NiMoS-P123 and NiMoS catalysts, the latter being prepared in the absence of polymer. Both compounds contained MoS2 phase (~85 atomic% considering Mo atoms), a similar amount of mixed Ni-Mo-S phase (40–50% considering Ni) and some amount of NiS and Ni-oxidized impurity phases. The main differences between the two catalysts were a much larger specific surface area (126 m2·g−1 instead of 31 m²·g−1) and a better dispersion of the active phase as shown by the lower slab stacking (2.7 instead of 4.8) for NiMoS-P123, and the presence of C in NiMoS-P123 (9.4 wt.% instead of 0.6 wt.%), indicating an incomplete decomposition of the polymer during thermal treatment. Thanks to its larger specific surface area and lower slab stacking and therefore modification of active Mo site properties, the compound prepared in the presence of Pluronic® P123 exhibits a strong increase of the catalytic activity expressed per Mo atom for the transformation of 3-methylthiophene. Such improvement in catalytic activity was not observed for the transformation of benzothiophene likely due to poisonous residual carbon which results from the presence of Pluronic® P123 during the synthesis.

Application of Fibrous TiO2 as a Photocatalyst in Aqueous Media

2006 ◽  
Vol 45 ◽  
pp. 951-956
Author(s):  
Hidekazu Tanaka ◽  
Ikuyo Higashio ◽  
Keiichi Watanabe ◽  
Yoko Suyama
Keyword(s):  
Methylene Blue ◽  
Photocatalytic Activity ◽  
Catalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Uv Irradiation ◽  
Anatase Phase ◽  
Aqueous Media ◽  
Rutile Phase ◽  
High Photocatalytic Activity

Fibrous TiO2 with ca. 0.16 mm in width and 5 - 6 cm in length was prepared by drying a suspension of monodispersed anatase particles at 363 K in air. The TiO2 fibers thus obtained were thermally treated at the temperatures ranging from 363 to 1273 K for 1 h in air. Elevating the treating temperature increases the crystallinity of anatase phase and reduces the specific surface area from 98 to 5 m2/g due to the sintering of particles. The rutile phase appears at 1273 K by transformation of anatase phase. A photocatalytic activity of the fibers was examined by decomposition of methylene blue (MB) in water under UV irradiation centered at 365 nm. The fibers decomposed the MB in aqueous media under UV irradiation, indicating that the fibers possess a high photocatalytic activity. The catalytic activity is considered to be enhanced on increasing the crystallinity of anatase phase, nevertheless, that decreased with generation of rutile phase.

scholarly journals Green Method for Synthesis of Gold Nanoparticles Using Polyscias scutellaria Leaf Extract under UV Light and Their Catalytic Activity to Reduce Methylene Blue

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Yoki Yulizar ◽  
Tresye Utari ◽  
Harits Atika Ariyanta ◽  
Digha Maulina
Keyword(s):  
Methylene Blue ◽  
Gold Nanoparticles ◽  
Catalytic Activity ◽  
Leaf Extract ◽  
Uv Light ◽  
Reduction Rate ◽  
Hydroxyl Groups ◽  
Face Centered Cubic ◽  
Pseudo First Order Reaction ◽  
Aqueous Fraction

The aqueous fraction of Polyscias scutellaria leaf extract (PSE) has been used as a reducing agent and stabilizer in the green synthesis of gold nanoparticles (AuNPs). UV-Vis spectrophotometry, particle size analyzer (PSA), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy-selected area electron diffraction (TEM-SAED), and X-ray diffraction (XRD) were used to characterize AuNPs. The AuNPs have a size of 5–20 nm and have a face centered cubic (fcc) crystal structure and are stable for 21 days. Phenolic compounds, which are secondary metabolites of PSE, act as an active compound to reduce Au3+ ion to Au0, as well as stabilize the AuNPs through their surface interaction with carbonyl and hydroxyl groups of phenols. AuNPs exhibit excellent catalytic activity for the reduction of methylene blue with NaBH4. The reduction of methylene blue using AuNPs catalysts is a pseudo-first-order reaction with a reduction rate constant (kobs) of 0.0223 min−1.

scholarly journals Peroxidase-Like Activity of Ferrihydrite and Hematite Nanoparticles for the Degradation of Methylene Blue

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Nicolaza Pariona ◽  
M. Herrera-Trejo ◽  
J. Oliva ◽  
A. I. Martinez
Keyword(s):  
Methylene Blue ◽  
Catalytic Activity ◽  
Surface Area ◽  
Catalytic Properties ◽  
High Surface ◽  
High Surface Area ◽  
Catalytic Process ◽  
Hematite Nanoparticles ◽  
High Crystallinity ◽  
Average Size

The peroxidase-like catalytic properties of 2-line ferrihydrite (2LFh) and hematite nanoparticles (NPs) for the degradation of methylene blue (MB) were studied. It is highlighted that the hematite NPs were prepared from the transformation of the metastable 2LFh NPs. It was found that the 2LFh NPs exhibited poor crystallinity with an average size of 5 nm, while the hematite NPs exhibited high crystallinity with an average size ofca. 100 nm. It was found that the total degradation of MB occurred for hematite NPs, while only a maximum degradation of 69% was possible for the 2LFh NPs. The Michaelis–Menten parameters indicated that the hematite NPs present higher catalytic activity than the 2LFh NPs at basic pH. It was found that the ordered surface of the hematite NPs has a stronger effect for the degradation of MB than its low surface area. It was concluded that the crystal planes of the hematite NPs affect the catalytic process more significantly than the high surface area of 2LFh NPs.

scholarly journals Porous Wood Decorated with Gold Nanoparticles as Flow-through Membrane Reactor for Catalytic Hydrogenation of Methylene Blue and 4-Nitrophenol

2021 ◽  
Author(s):  
Yuanyuan Yu ◽  
Qingtong Zhang ◽  
Mingchao Chi ◽  
Hongrui Jiang ◽  
Xi Liu ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Gold Nanoparticles ◽  
Catalytic Activity ◽  
Catalytic Hydrogenation ◽  
Organic Contaminants ◽  
Low Cost ◽  
Three Dimensional ◽  
Wood Chip ◽  
Flow Process ◽  
Au Nps

Abstract In this study, gold nanoparticles (Au NPs) were decorated into Paulownia Sieb. et Zucc. chip. Lignin, as one main component of wood, contains the reducing groups e.g. hydroxyl, carbonyl and aldehyde groups. Under sunlight irradiation, Au (III) diffused into wood was in situ reduced by lignin to form gold nanoparticles. Therefore, the Au NPs/Wood was successfully fabricated by this facile and green procedure. Meanwhile, the three-dimensional interpenetrating network of wood prevented the aggregation of Au NPs which retained its catalytic activity. Methylene blue and 4-nitrophenol were adopted as model organic contaminants to evaluate the catalytic hydrogenation ability of the Au NPs/Wood. The analyses of XRD, SEM, ICP-MS and XPS indicated that Au NPs were successfully immobilized in wood chip. The degradation results revealed that the Au NPs/Wood has excellent catalytic activity for methylene blue and 4-nitrophenol hydrogenation under batchwise and continuous flow process. Meanwhile, the Au NPs/Wood also exhibited excellent recyclability. The hydrogenation efficiency of MB and 4-NP still reaches more than 90% after 8 cycles. This study provides a new solution for green and low-cost fabrication of Au NPs/Wood which has broad application prospects in wastewater treatment.

scholarly journals Synthesis and catalytic activity of pluronic stabilized silver–gold bimetallic nanoparticles

RSC Advances ◽  
2014 ◽  
Vol 4 (94) ◽  
pp. 52279-52288 ◽  
Author(s):  
Megan S. Holden ◽  
Kevin E. Nick ◽  
Mia Hall ◽  
Jamie R. Milligan ◽  
Qiao Chen ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Sodium Borohydride ◽  
Bimetallic Nanoparticles ◽  
Galvanic Replacement ◽  
Galvanic Replacement Reaction ◽  
Replacement Reaction ◽  
Silver Nps ◽  
Mediated Reduction

Silver–gold BNPs with enhanced catalytic activity in the sodium borohydride mediated reduction of 4-nitrophenol were synthesized using a modified galvanic replacement reaction between F127 stabilized silver NPs and HAuCl4.

Evaluation of Nanotechniques and Conventional Techniques for the Removal of Dioxins

2018 ◽  
Vol 9 (1) ◽  
pp. 79-84
Author(s):  
Vaishali V. Shahare ◽  
Rajni Grover ◽  
Suman Meena
Keyword(s):  
Soil Sample ◽  
Human Health ◽  
Surface Area ◽  
Contaminated Soil ◽  
Conventional Treatment ◽  
Volume Ratio ◽  
Soil Samples ◽  
Dioxins And Furans ◽  
Palladized Iron ◽  
The Impact

Background: The persistent dioxins/furans has caused a worldwide concern as they influence the human health. Recent research indicates that nonmaterial may prove effective in the degradation of Dioxins/furans. The nanomaterials are very reactive owing to their large surface area to volume ratio and large number of reactive sites. However, nanotechnology applications face both the challenges and the opportunities to influence the area of environmental protection. Objective: i) To study the impact of oil mediated UV-irradiations on the removal of 2,3,7,8-TCDD, 2,3,7,8-TCDF, OCDD and OCDF in simulated soil samples. ii) To compare the conventional treatment methods with the modern available nanotechniques for the removal of selected Dioxins/furans from soil samples. Methods: The present work has investigated an opportunity of the degradation of tetra and octachlorinated dioxins and furans by using oil mediated UV radiations with subsequent extraction of respective dioxins/furans from soils. The results have been compared with the available nanotechniques. Results: The dioxin congeners in the simulated soil sample showed decrease in concentration with the increase in the exposure time and intensity of UV radiations. The dechlorination of PCDD/Fs using palladized iron has been found to be effective. Conclusion: Both the conventional methods and nanotechnology have a dramatic impact on the removal of Dioxins/furans in contaminated soil. However, the nanotechniques are comparatively costlier and despite the relatively high rates of PCDDs dechlorination by Pd/nFe, small fraction of the dioxins are recalcitrant to degradation over considerable exposure times.

Preparation of Strong Acid Catalysts by Sulfate Treatment of Calcined Boehmite

1992 ◽  
Vol 57 (11) ◽  
pp. 2241-2247 ◽  
Author(s):  
Tomáš Hochmann ◽  
Karel Setínek
Keyword(s):  
Catalytic Activity ◽  
Surface Area ◽  
Aluminum Sulfate ◽  
Solid Acid ◽  
Strong Acid ◽  
Acid Strength ◽  
Solid Acid Catalysts ◽  
Acid Catalysts ◽  
Preparation Methods ◽  
Indicator Method

Solid acid catalysts with acid strength of -14.52 < H0 < -8.2 were prepared by sulfate treatment of the samples of boehmite calcined at 105-800 °C. Two preparation methods were used: impregnation of the calcined boehmite with 3.5 M H2SO4 or mixing of the boehmite samples with anhydrous aluminum sulfate, in both cases followed by calcination in nitrogen at 650 °C. The catalysts were characterized by measurements of surface area, adsorption of pyridine and benzene, acid strength measurements by the indicator method and by catalytic activity tests in the isomerization of cyclohexene, p-xylene and n-hexane. Properties of the catalysts prepared by both methods were comparable.

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