Nanochemistry Research
Volume:3 Issue: 1, Winter and Spring 2018

The increasing attention being paid to metallic nano particles (MNPs) is due to their intensive applications in different areas of science such as medicine, chemistry, agriculture, and biotechnology. The main methods for nanoparticle production are chemical and physical approaches that are often costly and potentially harmful to the environment. Since the eco-friendly synthesis of NPs with different chemical compositions, sizes, shapes and controlled dispersity is an important aspect of nano biotechnology and green nanotechnology, biosynthesis of nanoparticles has been proposed as a cost-effective and environmental-friendly alternative to chemical and physical methods. Plants contain abundant natural compounds such as alkaloids, flavonoids, saponins, steroids, tannins and other nutritional compounds. These natural products are derived from various parts of the plant such as leaves, stems, roots, shoots, flowers, barks, fruits and seeds. Since the plant extract contains various secondary metabolites, it acts as the reducing and stabilizing agent for the bioreduction reaction to synthesize the novel metallic nanoparticles. This approach has been actively pursued in recent years as an alternative, efficient, inexpensive, and environmentally safe method for producing nanoparticles with specified properties. The present review focuses on the synthesis of MNPs with particular emphasis on biological synthesis using plant extracts and most commonly proposed mechanisms regarding the antibacterial properties of nanoparticles.

An efficient and simple magnetic solid phase extraction based on the use of CoFe3O4 nanoparticles grafted multi-walled carbon nanotubes (MWCNTs) as adsorbent coupled with surfactant enhanced spectrofluorimetric detection was developed for determination of ofloxacin from biological samples. The adsorbent uses the advantages of both magnetic nanoparticles (i.e., magnetic separation) and MWCNTs (i.e., high adsorption capacity). The main factors affecting the quantitative recovery including SDS concentration, pH, extraction and desorption times, adsorbent amount, and desorption conditions were investigated in detail. Under the optimized conditions, the calibration curves were linear over a wide concentration range of 100-750 ng mL-1 with detection limit (LOD) of 23 ng mL-1. The relative standard deviation (RSD %) of 3.3% for concentration of 250 ng mL-1, n = 5 and the preconcentration factor of 93 were obtained. Finally, the proposed method was successfully applied to the extraction and preconcentration of ofloxacin in human plasma samples.

A biofuel cell is a device for converting chemical energy to electrical energy by a simple way. A high-impact anode is prepared in this research. Here, carboxylated multiwall carbon nanotube (COOH-MWCNT), polydiallyldimethyl ammonium chloride (PDDA) and alcohol dehydrogenase were cast on modified glassy carbon with polymethylene green to construct the bioanode for biofuel cell. The polymethylene green is used as an electron mediator for NAD+ that is coenzyme for alcohol dehydrogenase. This new bioanode construction has a good storage and operational stability. The modified electrode was characterized by cyclic voltammetry. The biofuel cell was made with bioanode and carbon-platinum cathode, with and without membrane, and characterized by linear sweep voltammetry to obtain polarization curve for biofuel cell assembly. The biofuel cells had power density 350 µW.Cm-2 and 1713μW.Cm-2, with membrane and membraneless, respectively. The open circuit voltage of both biofuel cells was 0.28V for more than 1 hour. The anode easy construction and simple cell design make it useful for implant medical instruments.

The present study reports the synthesis of N-doped TiO2 photocatalyst for the degradation of caffeine using mechanochemical grinding method from the mixture of titania/urea followed by calcination at 400 ⁰C. The phase composition, particle size, surface area, morphology and optical properties were characterized. The XRD results revealed that anatase is dominant and the size of crystal is decreased from 35.8 to 33 nm after mechanical doping. An improved surface area of 42.9 m2g-1 is also reported. The morphology from SEM also showed a uniform yellow-like powder indicating complete dispersion of nitrogen on the TiO2 surface. The prepared sample showed visible-light absorption in the region 430 nm corresponding to band gap energy 2.88 eV, indicating its potential applications as a visible light induced photocatalyst. Photocatalytic oxidation of caffeine were investigated in 300 minutes irradiation time and N-doped TiO2 demonstrated the higher removal efficiency of 97% compared to commercial TiO2 powder with 91% efficiency at the same experimental condition.

A simple, low-cost and an eco-friendly synthesis of Ir-doped titanium dioxide nanoparticles (TiO2 NPs) with an anatase phase by the microwave-assisted method using an aqueous solution of titanium tetra-isopropoxide (TTIP) and iridium (III) chloride monohydrate. The synthesized Ir-doped TiO2 NPs were characterized by using various spectro-analytical techniques for the confirmation of NPs. The photocatalytic activity of the synthesized Ir-doped TiO2 NPs has been evaluated by taking 2-chlorophenol (2-CP), 4-chlorophenol (4-CP), 2,4-dichlorophenol (2,4-DCP) and 2,4,6-trichlorophenols (2,4,6-TCP) as model water contaminant pollutants under sunlight irradiation. The photocatalytic conversion is approximately 84.24%, 81.22%, 76.01% and 72.11% of 2-CP, 4-CP, 2,4-DCP and 2,4,6-TCP respectively, by using the synthesized Ir-doped TiO2 NPs. The efficient photocatalytic degradation was observed in the degradation of 2-CP in 60 min of sunlight irradiation. The rate equation of photocatalytic degradation mechanism was followed pseudo-first order kinetics. Finally, the screening of antimicrobial activity by paper disc method against few bacteria, such as Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa), Bacillus subtilis (B. subtilis) and Staphylococcus aureus (S. aureus) and fungi such as Aspergillus niger (A. niger) and Candida albicans (C. albicans), showed that the prepared Ir-doped TiO2 NPs have the prominent results.

As a novel performance, methanol gas conversion to dimethoxymethane (DMM) in one-step based on Fe-Mo-O (iron molybdate mixed oxides) catalysts with high surface area fabricated by metal organic frameworks (MOFs) precursors was improved. For this approach, at first, Fe(III) precursors (iron (III) 1,3,5-benzenetricarboxylate (MIL-100 (Fe) and iron terephthalate (MOF-235)) and Mo(VI) precursor ((NH4)6Mo7O24·4H2O) were synthesized. The catalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) analysis, temperature programmed desorption (NH3-TPD), dynamic light scattering (DLS) technique, Brunauer–Emmett–Teller analysis (BET) and inductively coupled plasma optical emission spectroscopy (ICP-OES) techniques. Application of MOFs as precursors was provided fabricated catalysts with high specific surface area which subsequently afforded higher selectivity and productivity of dimethoxymethane. Novel catalytic performances can be due to synergistic effect between Mo(VI) and Fe(III) species which leads to catalysts with porous structure. As a result, with a Mo:Fe molar ratio of 3, the best catalyst was obtained which exhibited 43% conversion, 92% selectivity and 39% yield, respectively.

CO2 is the main greenhouse gas emitted from the combustion of fossil fuels and is considered a threat in the context of global warming. Carbon capture and storage (CCS) schemes embody a group of technologies for the capture of CO2 from power plants, followed by compression, transport, and permanent storage. Key advances in recent years include the further development of new types of porous materials with high affinity and selectivity toward CO2 for optimizing the energy penalty of capture. In this regard, microporous metal-organic frameworks (MOFs) represent an opportunity to create next-generation materials that are optimized for real-world applications in CO2 capture. MOFs have great potential in CCS because they can store greater amounts of CO2 than other classes of porous materials, and their chemically-adjustable organic and inorganic moieties can be carefully pre-designed to be suitable for molecular recognition of CO2. Taking into account the nature of physisorption and inherent polarity of CO2 molecules, addressing materials with both a large surface area and polar pores for strong CO2 binding affinity is an effective method. Decorating the pores of MOFs with some specific functional groups by directly using functionalized organic linkers or postsynthetic modification, that have high binding affinity to CO2 molecules, is among the most promising strategies has been pursued to achieve high-performance CO2 uptake. This review highlights the literature reported on MOFs with amide-decorated pores for CO2 capture, showing the effects of amide groups on uptake capacity, selectivity and adsorption enthalpies of CO2.

In the present work, ZnO - SiO2 and Bi2O3– CuO nanocomposites have been prepared by sol gel with alternate precursors existing in literature. They are characterised by XRD, SEM,UV, FTIR and photoluminescence  spectra .The XRD results indicate a crystallite size of  approximately 80 nm for both nanocomposites. SEM image shows a heterogeneous particle size for both samples. The band gap of ZnO - SiO2 and Bi2O3– CuO obtained from Taucs plot is 4.1 eV and 2.85 eV, respectively. PL spectra show high intensity absorption for ZnO-SiO2 in comparison to   Bi2O3–CuO. The composites of Bi2O3–CuO is recommended for efficient optical coating against the coating made from Bi2O3.

Nanostructures of magnesium oxide is one of the most attractive materials which have shown various applications in many aspects of industries. So, finding a controllable and inexpensive technique to produce desirable nanostructures of MgO is valuable. In this work, magnesium oxide (MgO) with different morphologies was successfully prepared via a simple solid-state method. The molar ratio of sodium hydroxide to magnesium salt precursor was obtained 1 to 8. Furthermore, the effect of different magnesium precursors (magnesium chloride and magnesium acetate) on the morphology of MgO was investigated. It was shown that adding halide salts (NaX) to the solid-state reaction media, in spite of the noteworthy influence on the product morphology, facilitate the formation of MgO phase from Mg(OH)2. The synthesized magnesium oxide particles were characterized by Fourier transform infrared (FTIR) spectrometer, scanning electron microscope (SEM) and X-ray diffraction (XRD). Synthesized magnesium oxide particles were used to remove congored dye from waste water.

Objective.Chlorhexidine gluconate (CHX) is an irrigant with a  reasonable antibacterial ability and rather high permeability yet often fails to remove the smear layer. To solve this problem, CHX is upgraded through its complexion with chitosan (CS). Methods.Molar roots are split longitudinally by a rotary diamond saw. Chlorhexidine-chitosan (CHX-CS) is made by combination of CHX 2% and CS and adding Glutaraldehyde (GA) as a linker agent, followed by a freeze-drying process. Results.For the first time, CHX-CS is synthesized through linking of CHX and CS with GA. Subsequently CHX-CS is fully characterized with FT-IR (Fourier transform infrared spectroscopy), SEM (Scanning electron microscopy), DLS (dynamic light scattering), and antibacterial and water wettability tests. Significance.Ournew CHX-CS complex synergically preforms the advantages of both CHX and CS. Specifically, permeability and bactericidal effects of CHX are effectively coupled with CS smear layer removal capacity. Ease of synthesis, biocompatibility, better penetration, higher antibacterial activity, and economic benefits of this complex invite its dentistry and endodontistry applications.

Dyes are the most abundant hazardous components existing in the environment because of their extensive use in industries. So, in the present study, two isoreticular Zn(II)-MOFs, TMU-16 and TMU-16-NH2, were used for the adsorptive removal of harmful cationic dyes from aquatic medium. In order to improve the removal efficiency, optimization of the experimental conditions was carried out as a function of pH, MOF dosage, dye concentration and contact time. The maximum removal capacity was obtained at pH 12, 10 mg of MOF and 20 min as the contact time. The adsorption isotherms of each dye over both sorbents matched with the Langmuir model, and the adsorption kinetics followed the pseudo-second order kinetic model. The dye adsorption over TMU-16-NH2 is higher than that over TMU-16, indicating that the addition of amine groups in MOF network played an important role in the adsorption process, because of electrostatic interactions and hydrogen bonding. Thermodynamic studies indicated that adsorption process is spontaneous and endothermic.

In this research, nickel ferrite (NiFe2O4) nanoparticles (NFNs) are prepared through coprecipitation method, and applied for adsorption removal of a model organic pollutant, methyl orange (MO). The characterization of the prepared NFNs was performed using scanning electron microscopy (SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and transmission electron microscopy (TEM). Optimization and modeling of the removal of MO applying NFNs were performed via central composite design (CCD) and the influential parameters including nano-sorbent amount, dye initial concentration, contact time and pH were considered as input variables for CCD. A dye removal percentage of 99 % was achieved under the optimum condition established for MO removal that was in agreeing with the predicted value. Additionally, multi-layer artificial neural network (ML-ANN) was applied to acquire a predictive model of MO removal. The isothermal investigation of MO adsorption was performed by developing Langmuir, Freundlich and Temkin models, and results showed that experimental data were best fit in Freundlich model. Based on the adsorption kinetics studies, the pseudo-second-order kinetic model was the best model to describe the adsorption mechanism of MO onto NFNs.