Applied Nanoscience (v.5, #3)

Influence of carbon nanotubes support on the morphology of Fe3O4 nanoparticles by F. Zabihi; F. Taleshi; A. Salmani; A. Pahlavan; N. Dehghan-niarostami; M. M. Vadadi (267-272).
In this paper, the effects of carbon nanotubes as a support to the morphology and size of Fe3O4 magnetic nanoparticles have been investigated. The synthesis of Fe3O4/CNTs nanocomposite powder was performed by the direct precipitation method through ferric chloride (II) and (III) at room temperature. The prepared samples were analyzed by X-ray diffraction spectra, Fourier transform infrared spectroscopy, scanning electron microscopy and transmission electron microscopy. The results demonstrated considerable changes in the Fe3O4 nanoparticle size, also the morphology of Fe3O4/CNTs nanocomposite powder from agglomerative into rode shape.
Keywords: Carbon nanotube; Magnetic nanoparticles; Morphology; Nanocomposite; Direct precipitation

Linear and non-linear optical properties of GaAs nanowires by Satyendra Singh; Pankaj Srivastava (273-279).
The linear and non-linear optical properties of different geometrical structures of gallium arsenide (GaAs) nanowires have been studied by employing ab initio method. We have calculated the optical response of four different GaAs nanowires, viz., two-atom linear wire, two-atom zigzag wire, four-atom square wire and six-atom hexagonal wire. We have investigated imaginary part of the zz component of the linear dielectric tensor and second-order susceptibility for different structures along with bulk material. We revealed that the strongest absorption occurs for four-atom square nanowire configuration.
Keywords: GaAs nanowires; Linear optical properties; Non-linear optical properties

Preparation of cotton linter nanowhiskers by high-pressure homogenization process and its application in thermoplastic starch by N. R. Savadekar; V. S. Karande; N. Vigneshwaran; P. G. Kadam; S. T. Mhaske (281-290).
The present work deals with the preparation of cotton linter nanowhiskers (CLNW) by acid hydrolysis and subsequent processing in a high-pressure homogenizer. Prepared CLNW were then used as a reinforcing material in thermoplastic starch (TPS), with an aim to improve its performance properties. Concentration of CLNW was varied as 0, 1, 2, 3, 4 and 5 wt% in TPS. TPS/CLNW nanocomposite films were prepared by solution-casting process. The nanocomposite films were characterized by tensile, differential scanning calorimetry, scanning electron microscopy (SEM), water vapor permeability (WVP), oxygen permeability (OP), X-ray diffraction and light transmittance properties. 3 wt% CLNW-loaded TPS nanocomposite films demonstrated 88 % improvement in the tensile strength as compared to the pristine TPS polymer film; whereas, WVP and OP decreased by 90 and 92 %, respectively, which is highly appreciable compared to the quantity of CLNW added. DSC thermograms of nanocomposite films did not show any significant effect on melting temperature as compared to the pristine TPS. Light transmittance (Tr) value of TPS decreased with increased content of CLNW. Better interaction between CLNW and TPS, caused due to the hydrophilic nature of both the materials, and uniform distribution of CLNW in TPS were the prime reason for the improvement in properties observed at 3 wt% loading of CLNW in TPS. However, CLNW was seen to have formed agglomerates at higher concentration as determined from SEM analysis. These nanocomposite films can have potential use in food and pharmaceutical packaging applications.
Keywords: Cotton linter; Starch; Water vapor permeability; Oxygen permeability; Differential scanning calorimetry

Spectroscopic and morphological investigation of chemically treated cellulose nanowhiskers (CNW) prepared from cotton sliver by Muhammad Nasir; Nasreen Fatima; Khalid Mohammed Khan; Durey Nayab Zahra; Nasir Ansar; Salman Tariq Khan (291-296).
Cellulose nanowhiskers were prepared from cotton sliver and chemically treated with acylating agents. FTIR spectroscopy and scanning electron microscopy were used to study the morphological changes after each chemical treatment when reinforced in unsaturated polyester resin.
Keywords: Cellulose nanowhisker; Cotton sliver; Scanning electron microscopy

Basella alba rubra spinach pigment-sensitized TiO2 thin film-based solar cells by N. Gokilamani; N. Muthukumarasamy; M. Thambidurai; A. Ranjitha; Dhayalan Velauthapillai (297-303).
Nanocrystalline TiO2 thin films have been prepared by sol–gel dip coating method. The X-ray diffraction results showed that TiO2 thin films annealed at 400, 450 and 500 °C are of anatase phase and the peak corresponding to the (101) plane is present in all the samples. The grain size of TiO2 thin films was found to increase with increasing annealing temperature. The grain size is found to be 20, 25 and 33 nm for the films annealed at 400, 450 and 500 °C. The structure of the TiO2 nanocrystalline thin films have been examined by high-resolution transmission electron microscope, Raman spectroscopy and FTIR spectroscopy. TiO2 thin films were sensitized by natural dyes extracted from basella alba rubra spinach. It was found that the absorption peak of basella alba rubra extract is at about 665 nm. The dye-sensitized TiO2-based solar cell sensitized using basella alba rubra exhibited a Jsc of 4.35 mA cm−2, Voc of 0.48 V, FF of 0.35 and efficiency of 0.70 %. Natural dyes as sensitizers for dye-sensitized solar cells are promising because of their environmental friendliness, low-cost production and fully biodegradable.
Keywords: Sol–gel; TiO2 nanocrystalline thin film; Dye-sensitized solar cell

Influences of carbon nanofillers on mechanical performance of epoxy resin polymer by Shraddha Singh; V. K. Srivastava; Rajiv Prakash (305-313).
The influence of multi-walled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GnPs) on epoxy resin was investigated to compare their mechanical properties. MWCNT/epoxy resin and GnP/epoxy resin composites were compared with each other for their tensile strength, compressive strength, Charpy Impact and Izod impact energy with the variation of weight percentage ratio of nanofiller ranging from 0.5, 1.0, 2.0 and 3.0, respectively. The result shows that GnP/epoxy resin composite gave better tensile and compressive strength compared to MWCNT/epoxy resin composite whereas Izod impact energy, Charpy impact energy and dynamic fracture toughness of MWCNT/epoxy resin composite resulted in better impact resistance than the GnP/epoxy resin composite. Thermal stability and microstructural properties of composites were measured using Thermogravimetric analysis (TGA), transmission electron microscope (TEM) and scanning electron microscope (SEM).
Keywords: Carbon; Composites; Mechanical properties; Thermogravimetric analysis; Scanning electron microscopy

Green synthesis, characterization and catalytic activity of palladium nanoparticles by xanthan gum by Amrutham Santoshi kumari; Maragoni Venkatesham; Dasari Ayodhya; Guttena Veerabhadram (315-320).
Here, we report the synthesis, characterization and catalytic evaluation of palladium nanoparticles (PdNPs) using xanthan gum, acting as both reducing and stabilizing agent without using any synthetic reagent. The uniqueness of our method lies in its fast synthesis rates using hydrothermal method in autoclave at a pressure of 15 psi and at 120 °C temperature by 10 min time. The formation and size of the PdNPs were characterized by UV–visible spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy and transmission electron microscopy. The catalytic activity of PdNPs was evaluated on the reduction of 4-nitrophenol to 4-aminophenol by sodium borohydride using spectrophotometry.
Keywords: Autoclave; Catalytic activity; 4-Nitrophenol; Palladium nanoparticle; Xanthan gum

Optimization of process parameters for ruthenium nanoparticles synthesis by (w/o) reverse microemulsion by S. U. Nandanwar; J. Barad; S. Nandwani; M. Chakraborty (321-329).
Taguchi OA factorial design method was used to identify the several factors that might affect the particle size of ruthenium nanoparticles prepared by the mixing of two reactive microemulsions. In the present work, the objective of evaluating the factors influencing the particle size had been improvised by studying two qualitative factors viz., effect of different reducing agents and effect of different co-surfactants. Using orthogonal experimental design and analysis technique, the system performance could be analyzed with more objective conclusion through only a small number of simulation experiments. Analysis of variance was carried out to identify the significant factors affecting the response and the best possible factor level combination was determined through. It was found that the formation of ruthenium nanoparticles, microemulsions were greatly influenced by the type of reducing agent used in the technique followed by water-to-surfactant molar ratio.
Keywords: Taguchi method; ANOVA; Ru nanoparticles; Microemulsions technique

Innovative biofilm inhibition and anti-microbial behavior of molybdenum sulfide nanostructures generated by microwave-assisted solvothermal route by Nilam Qureshi; Rajendra Patil; Manish Shinde; Govind Umarji; Valerio Causin; Wasudev Gade; Uttam Mulik; Anand Bhalerao; Dinesh P. Amalnerkar (331-341).
The incessant use of antibiotics against infectious diseases has translated into a vicious circle of developing new antibiotic drug and its resistant strains in short period of time due to inherent nature of micro-organisms to alter their genes. Many researchers have been trying to formulate inorganic nanoparticles-based antiseptics that may be linked to broad-spectrum activity and far lower propensity to induce microbial resistance than antibiotics. The way-out approaches in this direction are nanomaterials based (1) bactericidal and (2) bacteriostatic activities. We, herein, present hitherto unreported observations on microbial abatement using non-cytotoxic molybdenum disulfide nanostructures (MSNs) which are synthesized using microwave assisted solvothermal route. Inhibition of biofilm formation using MSNs is a unique feature of our study. Furthermore, this study evinces antimicrobial mechanism of MSNs by reactive oxygen species (ROS) dependent generation of superoxide anion radical via disruption of cellular functions.
Keywords: Biofilm; Antimicrobial; ROS; Molybdenum Sulfide; Solvothermal

A facile one-step green synthesis of stable gold nanoparticles (AuNPs) has been described using chloroauric acid (HAuCl4) and the leaf extract of Lantana camara Linn (Verbenaceae family) at room temperature. The leaf extract enriched in various types of plant secondary metabolites is highly efficient for the reduction of chloroaurate ions into metallic gold and stabilizes the synthesized AuNPs without any additional stabilizing or capping agents. Detailed characterizations of the synthesized gold nanoparticles were carried out by surface plasmon resonance spectroscopy, transmission electron microscopy, dynamic light scattering, Zeta potential, X-ray diffraction and Fourier transform-infrared spectroscopy studies. The synthesized AuNPs have been utilized as a catalyst for the sodium borohydride reduction of 4-nitrophenol to 4-aminophenol in water at room temperature under mild reaction condition. The kinetics of the reduction reaction has been studied spectrophotometrically.
Keywords: Lantana camara Linn; Gold nanoparticles; Catalytic reduction; Green synthesis; Phytochemicals

The aim of this paper is to study the effects of radiation absorption and chemical reaction on MHD free convection heat transfer flow of a nanofluid bounded by a semi-infinite flat plate in a rotating frame of reference. The plate is assumed to oscillate in time with steady frequency so that the solutions of the boundary layer are the similar oscillatory kind. The entire system rotates about the axes normal to the plate. The dimensionless governing differential equations for this investigation are solved analytically using perturbation method. The effects of various important parameters entering into the problem on velocity, temperature, skin friction and Nusselt number within the boundary layer are discussed for Cu–water-based nanofluid with the help of graphs. The predicted consequences obviously point out that the presence of nanoparticles in the base fluid improves the heat transfer process significantly. The results also show that the values of Nusselt number in case of nanofluid are more pronounced than that of micropolar fluid.
Keywords: Nanofluid; Chemical reaction; Thermal radiation; Rotating frame; Radiation absorption; MHD

Gold nanoparticles (AuNPs) capped with 2-mercapto succinic acid (MSA) were successfully applied for the determination of mercury in various water samples up to nanolevels without any interference. Alumina-coated MSA-capped AuNPs easily remove mercury species present in various samples. The absorbance spectrum was obtained at 547 nm. Other parameters like effect of pH, reagent concentration, interferences were studied. This method is simple, sensitive and successfully applied for the determination of mercury species in various water, soil and plant residues collected from different industrial areas.
Keywords: Gold nanoparticles; 2-Mercapto succinic acid; Activated alumina; Environmental samples

Pure ZnO and 2 % Cr-doped ZnO nanoparticles were synthesized by sol–gel technique. Powder X-ray diffraction reveals that Cr incorporates into the ZnO crystal lattice without disturbing the original hexagonal structure. Transmission electron microscopy measurements show that the average size of these nanoparticles is in the range 20–25 nm. Pure ZnO nanoparticles exhibit diamagnetism while Cr-doped ZnO exhibit saturated hysteresis loop at room temperature indicating ferromagnetic behavior. Nitrogen co-doping along with Cr in ZnO shows enhanced ferromagnetism with small antiferromagnetism.
Keywords: Nanoparticles; Ferromagnetism; X-ray diffraction; Electron microscopy

Synthesis of nanocrystalline titanium dioxide for photodegradation treatment of remazol brown dye by K. Santhi; P. Manikandan; C. Rani; S. Karuppuchamy (373-378).
A nanocrystalline TiO2 was successfully synthesized using simple aqueous peroxo route and subsequently the surface characterization of TiO2 was carried out using X-ray diffraction and Scanning electron microscopy. The synthesized nanocrystalline TiO2 successfully decomposed the aqueous remazol brown dye solution under UV light irradiation with and without ozone. The effects of pH, TiO2 dose and irradiation time for decomposition of dye solution were also evaluated. The maximum dye decomposition efficiency of 96.6 % was achieved with the minimal time of 45 min by UV/TiO2/O3 treatment. The present study clearly indicates that the peroxo route TiO2 nanoparticle is a promising material for industrial waste water treatment.
Keywords: Nanocrystalline; Titanium dioxide; Photocatalysis; Remazol brown dye

Hydraulic classifier system for fractionation of nano CaCO3 particles by H. F. Aly; M. A. Akl; Hesham M. A. Soliman; Aref M. E. AbdEl-Rahman; A. I. Abd-Elhamid (379-391).
A laboratory scale hydraulic classifier system was developed for calcium carbonate nanoparticles fractionation. The system is based on the differences in the settling velocity of particles in aqueous fluid at different dynamic viscosities along different settling stages. Different factors affecting the fractionation process were studied, such as the effect of water volume, L, terminal (settling) velocity in different stages, νs, CaCO3 feed concentration, g/L and flow rate (L/h) of the dispersed fluid solution. The particles obtained were characterized using SEM and showed that the developed system can fractionate particles within the size range 25–33 nm. A simple model for the results obtained is developed and discussed in terms of the different parameters affecting particles size is given. Further, the calcium carbonate used was characterized before and after fractionations using Vibratory sieve shaker, SEM, EDS, XRD and FTIR.
Keywords: Calcium carbonate; Nanoparticles; Fractionation; Hydraulic classifier