Enhanced Oxidation of p-Toluidine Using Supported Zeolite Nanoparticles.

Supported nanomaterials are becoming increasingly important in many industrial processes because of the need to improve both the efficiency and environmental acceptability of industrial processes. The unique properties of supported nanomaterials have attracted researchers to develop efficient catalytic materials in nanoscale. The extremely small size of the particles maximizes the surface area exposed to the reactant, allowing more reactions to occur. The environmental hazards resulting from the conventional manufacturing procedures for organic fine chemicals and intermediates by classical oxidation catalysis using mineral acids have forced chemical industries to seek less polluting processes. The present study aimed to oxidize p-toluidine by hydrogen peroxide in the presence of magnetite supported on nanocrystalline titanium silicalite-1 (M/NTS) zeolite at ambient temperature. The products detected are 4,4'-dimethylazobenzene as major product and 4,4'-dimethylazoxybenzene as minor product. Good selectivity, low cost, low wastage of materials and enhanced environmental friendliness of heterogeneous magnetite nanoparticle supported zeolite catalysts were observed. The effect of various reaction parameters such as mole ratio, catalyst weight and reusability of catalyst were studied. At the optimum reaction conditions, the oxidation activity of M/NTS catalyst was compared with M/NS catalyst, and it was found that titanium in the framework of M/NTS provided higher activity and selectivity.

Synthesis of Iron Oxide@Pt Core-Shell Nanoparticles for Reductive Conversion of Cr(VI) to Cr(III) and Antibacterial Studies.

Herein, we report the facile synthesis of Iron oxide@Pt core-shell nanoparticles (NPs) by facile two step synthesis process. The first step follows the growth of iron oxide nanoparticle by thermal decomposition process while the second step deals with the formation of iron oxide@Pt core-shell nanoparticles by the chemical reduction method. The synthesized core-shell nanoparticles were characterized by several techniques and used for the catalytic reductive translation of Cr(VI) to Cr(III) in the presence of formic acid by a UV-vis spectrophotometer. The UV photo-spectrometer analysis confirmed the conversion efficiency from 12% to as high as 98.8% at the end of 30 minutes. Thus, the presence of Iron oxide @Pt core-shell nanoparticles (NPs) can be effectively used as a catalyst for the reducion of Cr(VI) to Cr(III) ions. Additionally, antibacterial studies were performed for the prepared core-shell nanoparticles against two bacterial strains, i.e., gram (+ve) Staphylococcus Aureus (S. Aureus) and gram (-ve) Escherichia Coli (E. Coli).

Selective Monoacylation of Mesitylene Using Hierarchical Nanocrystalline ZSM-5 Catalyst.

Monoacylated mesitylene is an important precursor used in fine chemical industries In the present work, acylation of mesitylene was carried out using hierarchical ZSM-5 catalyst to prepare 2',4',6'-trimethyl acetophenone (monoacylated Mesitylene). The catalyst hierarchical ZSM-5 possessing three generations of micro-, meso-, and macroporosities was fabricated through a dual-template approach using tetrapropylammonium hydroxide (TPAOH) and poly(methyl methacrylate) (PMMA) latex particles as micropore and macropore templates, respectively. The catalyst is well characterized by XRD, FTIR and SEM. The liquid phase reactions were carried out in the temperature range of 30-50 #x00B0;C. The effect of various parameters such as mole ratio of reactants, catalyst loading, and temperature on the rates of reaction has been investigated. The result shows that the present process gives 100% selective towards the desired product, that is, 2',4',6'-trimethyl acetophenone, because hierarchical ZSM-5 allows faster diffusion of the products out of the catalyst provide an important increase in the activity and selectivity.

Cu-Doped SnO2 Nanoparticles: Synthesis and Properties.

In this work, a simple, co-precipitation technique was used to prepare un-doped, pure tin oxide (SnO2). As synthesized SnO2 nanoparticles were doped with Cu2+ ions. Detailed characterization was carried out to observe the crystalline phase, morphological features and chemical constituents with opto-electrical and magnetic properties of the synthesized nanoparticles (NPs). X-ray diffraction analysis showed the existence of crystalline, tetragonal structure of SnO2. Both the sample synthesized here showed different crystalline morphology. The band gap energy (Eg) of the synthesized sample was estimated and it was found to decrease from 3.60 to 3.26 eV. The band gap energy reduced due to increase in Cu2+ dopant amount inside the SnO2 lattice. Optical properties were analyzed using absorption spectra and Photoluminescence (PL) spectra. It was observed that Cu2+ ions incorporated SnO2 NPs exhibited more degradation efficiencies for Rhodamine B (RhB) dye compared to un-doped sample under UV-Visible irradiation. The dielectric characteristics of un-doped, pure and Cu2+ incorporated SnO2 nanoparticles were studied at different frequency region under different temperatures. The ac conductivity and impedance analysis of pure and Cu2+ incorporated SnO2 nanoparticles was also studied. The magnetic properties of the synthesized samples were analysed. Both the sample showed ferromagnetic properties. The research indicated that the Cu2+ ions doping can make the sample a promising candidate for using in the field of optoelectronics, magneto electronics, and microwave devices.

Enhanced Photocatalytic Behavior of (GO/Cu2O) Composite with Cu2O Being Synthesized Through Green Route.

Graphene oxide/Cuprous oxide (GO/Cu2O) composite is a visible light photocatalyst for the degradation of dyes. A simple and efficient approach for preparing GO/Cu2O composite adopted in this study involves reducing cuprous oxide precursors in the presence of graphene oxide using an aqueous solution of pulp derived from banana fruit. The GO/Cu2O composite was characterized by Fourier transform infrared spectroscopy (FT-IR), Diffused reflectance Ultraviolet visible spectroscopy (DRS UV-Vis), Raman spectroscopy and Field Emission Scanning electron microscopy (FE-SEM). Cu2O particles were distributed randomly on the graphene oxide sheets due to the template effect of GO. The results showed higher photocatalytic activity for the composite (band gap 2.13 eV), for the degradation of the organic dyes (Methylene blue and Rhodamine-B). The enhanced photocatalytic activity is due to effective charge transfer from GO to Cu2O, and high specific surface area which improves the effective separation of the generated electron-hole pairs. Our present study is inspired by a facile, low cost, green production of (GO/Cu2O) composite whose photocatalytic activity can be extended to degradation of all other water-born textile dyes.

Recent Advances and Perspectives of Carbon-Based Nanostructures as Anode Materials for Li-ion Batteries.

Rechargeable batteries are attractive power storage equipment for a broad diversity of applications. Lithium-ion (Li-ion) batteries are widely used the superior rechargeable battery in portable electronics. The increasing needs in portable electronic devices require improved Li-ion batteries with excellent results over many discharge-recharge cycles. One important approach to ensure the electrodes' integrity is by increasing the storage capacity of cathode and anode materials. This could be achieved using nanoscale-sized electrode materials. In the article, we review the recent advances and perspectives of carbon nanomaterials as anode material for Lithium-ion battery applications. The first section of the review presents the general introduction, industrial use, and working principles of Li-ion batteries. It also demonstrates the advantages and disadvantages of nanomaterials and challenges to utilize nanomaterials for Li-ion battery applications. The second section of the review describes the utilization of various carbon-based nanomaterials as anode materials for Li-ion battery applications. The last section presents the conclusion and future directions.

Transformation of Commercial TiO2 into Anatase with Improved Activity of Fe, Cu and Cu-Fe Oxides Loaded TiO2.

In the present study copper and iron oxides loaded TiO2 catalysts are prepared by the deposition-precipitation method (DP) and the photocatalytic efficiency of these catalysts are tested for the degradation of Rose Bengal dye (Acid Red 94) under sunlight. The catalysts are characterized by XRD, TEM and UV-vis diffuse reflectance spectral analysis. It is interesting to note that the rutile form of commercial TiO2 is competently converted into anatase after loading oxides of Cu, Fe and Cu-Fe on TiO2 as evident from XRD analysis. This result is consistence with the result obtained in UV-vis diffuse reflectance spectra. TEM analysis confirms the nano particles of Cu and Fe deposited on TiO2. Photocatalytic studies were performed in a batch reactor under solar radiation. Preliminary studies are performed to understand the photocatalytic degradability of the dye and optimization of catalyst weight and dye concentration. Kinetic studies were done at different dye concentrations and it was found that the rate equation followed first order kinetics and obeyed Langmuir-Hinshelwood model. The comparison of the activity of blank TiO2, copper or/and iron oxides loaded TiO2 catalysts showed that the Cu and Fe oxide loaded catalysts are more active than pure TiO2 and also the Cu-Fe oxides co-loaded TiO2 catalysts showed much best activity. The order of activity of the catalysts is in the following order: Cu-Fe/TiO2 > Fe/TiO2 > Cu/TiO2 > TiO2. The enhanced activity of metal oxide loaded TiO2 is attributed to the presence of TiO2 in anatase form after loading, which enhanced the charge transfer from the TiO2 to adsorbed molecules for reaction.

Advances in Screening, Detection and Enumeration of Escherichia coli Using Nanotechnology-Based Methods: A Review.

Amongst the various microorganisms found as contaminants in food and water samples, Escherichia coli (E. coli) is one of the most predominant bacteria observed. The presence of the various strains of E. coli, pathogenic or non-pathogenic, in either food or water samples serves as an indicator of faecal contamination and helps to determine the hygienic condition, potability and safety of a given water or food sample for consumption. Although several conventional microbial analytical methods and the more advanced biochemical and molecular biology based methods exist for detection of E. coli, these are laden with several limitations. Nanotechnology offers cheaper, more reliable, quicker and more sensitive detection platforms for screening and/or enumerating the load of E. coli in a given sample. The present review outlines in brief the conventional methods available for E. coli detection enlisting the drawbacks of the same. Against this background, nanotechnology-based sensing systems developed for detection and capturing of E. coli so far have been highlighted. The most commonly developed nanosensors employ gold or silver nanoparticles with magnetic nanobeads also being currently employed for sensor development. Further, the evolution of green nanoparticle technology and its application in E. coli sensing has been explored with various examples of carbon dots, graphitic carbon nitride, glycopolymers and rice husk ash being cited. Furthermore, the development of nanosensors for E. coli using bimetallic nanoparticles has also been reviewed. These nanobased sensors have proved to exhibit high sensitivities and low detection limits for E. coli. However, approaches to enhance the sensitivity to detection even further lower limits and provide nanosensors as multifunctionalized detection tools for multiple pathogenic strains are underway.

Nanocrystalline Hierarchical ZSM-5: An Efficient Catalyst for the Alkylation of Phenol with Cyclohexene.

In this paper, authors report the synthesis of nanocrystalline hierarchical zeolite ZSM-5 and its application as a heterogeneous catalyst in the alkylation of phenol with cyclohexene. The catalyst was synthesized by vacuum-concentration coupled hydrothermal technique in the presence of two templates. This synthetic route could successfully introduce pores of higher hierarchy in the zeolite ZSM-5 structure. Hierarchical ZSM-5 could catalyse effectively the industrially important reaction of cyclohexene with phenol. We ascribe the high efficiency of the catalyst to its conducive structural features such as nanoscale size, high surface area, presence of hierarchy of pores and existence of Lewis sites along with Brønsted acid sites. The effect of various reaction parameters like duration, catalyst amount, reactant mole ratio and temperature were assessed. Under optimum reaction conditions, the catalyst showed up to 65% selectivity towards the major product, cyclohexyl phenyl ether. There was no discernible decline in percent conversion or selectivity even when the catalyst was re-used for up to four runs. Kinetic studies were done through regression analysis and a mechanistic route based on LHHW model was suggested.

Nanocrystals of Zeolite ZSM-5 as Catalysts for the Liquid Phase Benzylation of Anisole with Benzyl Alcohol.

The current paper reports the application of nanocrystalline form of zeolite ZSM-5 in lieu of Friedel Crafts catalysts in the benzylation of anisole using benzyl alcohol. There are many problems associated with the use and disposal of conventional catalysts due to their toxicity, corrosiveness and non-recyclability. Nanocrystalline zeolites can be a less polluting alternative to the conventional Friedel Crafts catalysts. Nanocrystalline ZSM-5 was synthesized by a facile method and was characterized using SEM, XRD and FTIR. The prepared nanocrystalline zeolite was then evaluated for its efficiency and selectivity in liquid phase benzylation of anisole. Optimum conditions of reaction time, temperature, quantity of catalyst and mole ratio of reactants were obtained. Kinetic studies were done to propose a mechanistic model for the catalyzed reaction. Results of this study suggest that the synthesized nanocrystals of zeolites are efficient, selective, stable, consistent and reusable catalysts. This catalyst thus holds the possibility of being a better alternative to homogeneous catalysts, from environmental and economic perspectives.

Enhanced Activity of Nanocrystalline Beta Zeolite for Acylation of Veratrole with Acetic Anhydride.

Friedel-Craft acylation of veratrole using homogeneous acid catalysts such as AlCl3, FeCl3, ZnCl2, and HF etc. produces acetoveratrone, (3',4'-dimethoxyacetophenone), which is the intermediate for synthesis of papavarine alkaloids. The problems associated with these homogeneous catalysts can be overcome by using heterogeneous solid catalysts. Since acetoveratrone is a larger molecule, large pore Beta zeolites with smaller particle sizes are beneficial for the liquid-phase acylation of veratrole, for easy diffusion of reactants and products. The present study aims in the acylation of veratrole with acetic anhydride using nanocrystalline Beta Zeolite catalyst. A systematic investigation of the effects of various reaction parameters was done. The catalysts were characterized for their structural features by using XRD, TEM and DLS analyses. The catalytic activity of nanocrystalline Beta zeolite was compared with commercial Beta zeolite for the acylation and was found that nanocrystalline Beta zeolite possessed superior activity.

Photocatalytic oxidation of phenolic pollutants and hydrophobic organic compounds in industrial wastewater using modified nonosize titanium silicate-1 thin film technology.

Nanocrystalline Titanium Silicate-1 (TS-1) with attractive physical and chemical properties is being explored for the degradation of phenol. A fully dispersible nanocrystalline zeolite TS-1 was prepared. The catalyst was characterized by DLS, XRD, TEM and BET analyses. XRD analysis confirmed that the diffraction pattern of the NPs (CP-0) was very similar to that of amorphous silica and the aged concentrated precursor sample CP-48 showed peaks characteristic of MFI. TEM analysis confirmed that the size of the crystal is about 30 nm. The photocatalytic oxidation of phenol was studied over nanocrystalline Titanium silicate-1 thin film flow reactor. The experimental parameters such as aeration, flow rate, solution pH and phenol concentration were optimized. The degradation efficiency of choro-substituted phenols are compared at optimum conditions. In addition, photocatalytic degradation efficiency of simulated phenolic waste water was studied. The results are significant, as the method adopted here can be extended for the treatment and purification of waste water and air using nanocrystalline Titanium silicate-1 thin film flow reactor.

Some observations on the synthesis of fully-dispersible nanocrystalline zeolite ZSM-5.

A facile method for the rapid synthesis of fully-dispersible ZSM-5 (Si/Al = 100) of about 30 nm size in high yield (about 91%) is described. The method comprises three steps, viz., concentration of an initial clear solution, low-temperature (80 degrees C) ageing of concentrated sol, and high-temperature (175 degrees C) hydrothermal treatment or microwave heating (175 degrees C) of aged concentrated sol. A simple vacuum-concentration method was used for the extraction of pure NPs of ZSM-5 in solution. XRD, FT-IR, TGA and ASAP characterizations showed that the NPs were partially crystalline. The concentration step accelerated the aggregation of primary units, which helps in the production of a large number of nucleation centers protected by TPA+ ions against aggregation. During low-temperature ageing, the number of critical sized nuclei increases, growing into zeolite. The high-temperature heating results in the complete growth of unreacted silica, giving high yields. A key factor for generating small non-aggregated zeolite crystals is the amount of water in the synthesis sol. The three-step method presented here produces a target material of small and uniform sized, non-aggregated ZSM-5 of about 30 nm in a short reaction time. The results are significant, as the synthesis method adopted here produces much uniform, non-aggregated nanocrystalline ZSM-5 in a shorter time with high yield.

Hierarchical zeolite beta: an efficient and eco-friendly nanocatalyst for the Friedel-Crafts acylation of toluene.

P-Methyacetophenone, the acylated product of toluene finds a wide range of applications in the flavors and fragrance industry. It is typically produced on an industrial scale by Friedel-Crafts acylation of toluene with acetic anhydride using homogeneous, corrosive and polluting acid catalysts such as aluminium chloride. The pollution problems related to this process such as the disposal of catalyst and treatment of acidic effluent needs to be replaced by a green process. The current work reports on the activity of hierarchical zeolite Beta in the liquid phase acylation of toluene with acetic anhydride. The liquid phase reactions were carried out in the temperature range of 60-140 degrees C in an autoclave. The effect of various reaction parameters such as time-on-stream (TOS), mole ratio of reactants, catalyst loading, and reaction temperature on the rates of reaction has been investigated. Under the optimum reaction conditions the performance of hierarchical zeolite Beta was compared with nanocrystalline zeolite Beta. It was found that hierarchical zeolite Beta catalyst exhibit higher activity, which is due to the hierarchical porosity and to the nano size of the Beta zeolite catalyst particles allows faster diffusion of the products out of the catalyst.

Rapid synthesis of MFI zeolite nanocrystals.

A rapid synthesis procedure for nonagglomerated silicalite nanocrystals has been developed. This was achieved by concentrating the precursor sol before 10-12 h of aging at 80 degrees C, followed by hydrothermal synthesis at 175 degrees C for 90 min. The high silica concentration in the concentrated sol accelerated the aggregation of primary units that were present early in the system. Thus, little silica nutrients were left for growth when the secondary particles were converted to zeolite during hydrothermal reaction. As a result, fully dispersible nanocrystals were obtained within a day instead of weeks as reported previously. The aggregation of primary units during the 80 degrees C aging process as well as the conversion of these aggregates into zeolite has been followed by DLS, XRD, and FTIR. In light of the new results, the nucleation and growth mechanisms of MFI zeolite that have been under debate in the literature were reexamined.