سال:1398 | دوره: | شماره: |تعداد مقالات:7

In this report an expeditious, manageable and uncomplicated advancement has been demonstrated in the field of nanoparticles for sensing dithiocarbamates (DTCs) Ziram, Zineb, and Maneb pesticides in environment and juice samples using cetyltrimethyl ammonium bromide (CTAB)-capped copper nanoparticles (CTAB-Cups) as colorimetric probe. The probe was prepared in aqueous solvent using CTAB and hydrazine monohydrate. Localized surface plasmon resonance band of the prepared sensor was scanned by UV– visible spectrophotometer. Further Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDX), zeta potential and dynamic light scattering (DLS) techniques were employed to reveal the interaction, functionality, surface characteristics and particle size. Probe was used competently for colorimetric sensing of Ziram, Zineb, and Maneb belonging to the DTCs group of pesticides. Sudden change in color from reddish wine to yellow was noted visibly and monitored on spectrophotometer, FTIR, EDX, zeta potential and DLS. The probe indicated very susceptible and selective colorimetric detection of DTCs within the range of 97. 9– 489. 3 ng/ml, 8. 8– 44. 1 ng/ml and 8. 4– 42. 4 ng/ml for Ziram, Zineb and Maneb. The designed method yielded very rapid and organized procedure for detection of DTCs with minimal sample preparations. The method was used for the analysis of DTCs spiked tap water, tomato extract, mango juice, and recoveries of DTCs were obtained within 95. 8– 108. 5% with relative standard deviation within 0. 14– 1. 11%.

The inverse spinel nanocrystalline pure and doped nickel ferrite particles were synthesized by co-precipitation method. The thick films of both pure and doped nickel ferrite nanoparticles were prepared by coating the material on glass substrate via screen printing method. The XRD was used to confirm cubic, crystalline nickel ferrites. The scanning electron microscopy confirms nanosized, cubic nanoparticles of nickel ferrite, and their morphology was investigated. The energy-dispersive spectroscopy was used to comprise elemental composition for pure and doped ferrites. Transmission electron microscopy was attributed for investigation of surface morphology, crystal structure identification of nickel ferrites. The FT-IR was used to find the vibrational frequencies, symmetric, asymmetric stretching and bending modes of metal oxide linkage. The thick films of nickel ferrite were employed for sensing phenomenon of gases such as LPG, NO2, CH3-OH, C2H5-OH, NH3 and petrol vapours. The pure nickel ferrite showed excellent results for ammonia and nitrogen dioxide gases up to 90. 42 and 86. 42, respectively. Manganese-and cobalt-doped ferrites were excellent for ammonia and petrol vapours. Modified nickel ferrite effect of dopants cobalt and manganese was investigated. Pure and doped ferrites showed excellent response and recovery for ammonia, NO2, petrol vapours and LPG gases.

The need to divulge the rapid synthesis, non-hazardous, cost effectiveness and eco-friendly methods for the synthesis of nanoparticles utilizing plants is of great importance. This is as a result of high toxicity associated with the chemical method of synthesizing nanoparticles. The aim of this study was to investigate the potency of the synthesized gold nanoparticle against selected human pathogens. Gold nanoparticles were synthesized by reacting 1 mM gold chloride solution with leaf extract of Annona muricata. The synthesized gold nanoparticles were characterized with UV– visible spectrophotometer, transmission electron microscope (TEM) and Fourier transformed infrared spectroscopy (FTIR). The antibacterial and antifungal activities of the synthesized gold nanoparticles were also investigated. The morphology, size, and structural properties of synthesized gold nanoparticles were determined with TEM analysis which showed spherical mono-dispersed structure with an average particle size of 25. 5 nm. FTIR analysis reveal band at 3271. 14, 2111. 91 and 1637. 82 cm− 1 corresponding to – N– H, – C=C, and – C– N functional groups that are responsible for the capping and stabilization of synthesized gold nanoparticles. The effectiveness of the gold nanoparticle against the test pathogens increases as the concentration of gold nanoparticle increases. The percentage of zones of inhibition of synthesized gold nanoparticle against test fungi and bacteria ranges from 30 to 66% and 40 to 54%, respectively. The potency of the synthesized gold nanoparticle against the selected fungi and bacteria increases with increase in concentration of gold nanoparticle. Therefore, the antibacterial and antifungal investigation revealed that the synthesized gold nanoparticles exhibited good antimicrobial activity.

The ferrite material with compositions Ni0. 7Cu0. 1Zn0. 2LaxFe2− xO4 (where x = 0, 0. 015, 0. 025, and 0. 035) was synthesized by oxalate co-precipitation method. The ferrite samples were characterized by thermo-gravimetric and differential temperature analysis (TG– DTA), energy-dispersive X-ray analysis (EDAX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (FE-SEM), and vibrating sample magnetometer (VSM) techniques. The EDAX analysis confirmed the formation of required stoichiometric ferrite samples. The formation of cubic spinel structure with the presence of weak ortho-ferrite phases was confirmed from X-ray diffraction analysis. The lattice constant of all the ferrites was found to be increase with increase in La3+ content. The presence of main two recognized strong absorption bands in the frequency range 400– 600 cm− 1 in the FTIR spectra shows the formation of well spinel ferrite. Morphological study shows that grain size of the ferrites lies in the range 16. 23– 24. 21 nm. It is observed that the saturation magnetization and magnetic moment of Ni– Cu– Zn ferrites decrease with La3+ content.

In this research, a simple and rapid method for the separation and preconcentration of trace amounts of crystal violet (CV) from aqueous sample solutions by modified magnetic nano-particles (MNPs) has been developed. The modification of magnetite nanoparticles was conducted by tetra ethoxysilane (TEOS) followed by micelles of anionic surfactant (SDS) to enhance the preconcentration of CV. To characterize the shape and structure of the nanoadsorbent, FT-IR and XRD procedures were used. Also, the average size of the synthesized nanoparticles was achieved between 30 and 40 nm by TEM technique. The effects of some important parameters such as: aqueous solution pH, adsorbent dosage, contact time, temperature and desorption conditions on the separation and concentration of CV were investigated. So, under optimal experimental conditions: aqueous solution pH 6, solution temperature = 20 ° C, 7 mg of adsorbent, 1 mL of eluent (0. 8 mL of acetonitrile + 0. 2 mL of acetic acid), the recovery of CV from river water samples was achieved 98. 32 ± 0. 056% (n = 5) in two short periods of time for extraction (5 min) and elution (2 min). The maximum sorption capacity of the nano-composite was determined to be 16. 37 mg/g. Also linear dynamic range and limit of detection were calculated to be 10– 2500 ppb and 1. 82 ppb, respectively. Finally, the proposed method was successfully applied for the separation and concentration of CV from the real water samples and the results were satisfied.

The zirconia– alumina nanocatalyst was prepared using microwave combustion method, and the effects of alumina/zirconia ratio, fuel-to-oxidizer ratio, and calcination temperature on its structural and chemical performance were examined. Furthermore, the most suitable synthesized nanocatalyst was impregnated using different dosages of sulfate group to improve the activity of the sample for the esterification reaction. The results revealed that there was a significant improvement in the crystalline structure of alumina and zirconia for the samples having the alumina/zirconia ratio of 2. It was also noted that some amorphous structures were observed for low fuel dosages, while the activity of the sample was reduced with higher fuel consumption than the stoichiometric ratio, which can be attributed to the increase in the crystallite size and formation of different alumina phases. Based on calcination results, non-considerable changes were observed in the morphology and activity of the catalyst. It can be concluded that the solution combustion method is suitable for nanocatalyst preparation without any requirement of further thermal treatment. In addition, the activity of the sample was enhanced by impregnation with H2SO4 where the conversion of 91. 6% was achieved. The catalyst showed high reusability at least for seven times as well as high stability of zirconia– alumina as a support.

Silver nanoparticles (Ag NPs) were synthesized using Alternanthera sessilis leaf and Oregano root extract in an eco-friendly fashion and their significant physicochemical and optochemical properties were ascertained for nano-defined characteristics. The UV– visible spectrum showed a single and distinct absorbance peak at 433 nm (Alternanthera sessilis) and 425 nm (Oregano), typical SPR (surface plasmon resonance) for silver. Structural studies revealed nano-crystal with face centre cubic (FCC) symmetry with monodispersed nature. SEM studies showed spherical-shaped particles and the purity determined from EDX spectrum. The synthesized Ag NPs showed that antibacterial activity was studied. There was a significant inhibitory effect toward clinically important pathogens viz. B. subtilis, S. aureus, P. aeruginosa, and E. coli exposed to Ag NPs at different concentrations.