Synthesis, Characterization and Antibacterial Properties of Silver Nanoparticles in Clay and Organic Polymers as Nanocomposites

In this study, silver nanoparticles (Ag NPs) with the small size (2.12–30.63 nm) were successfully synthesized in the lamellar space of montmorillonite (MMT), montmorillonite/chitosan (MMT/Cts), porous zeolite framework and external surface layer of talc by chemical reducing agent in the absence of heat treatment. The most favourable experimental condition for the synthesis of Ag NPs in the MMT, talc, zeolite nanocomposites (NCs) and silver/montmorillonite/chitosan bionanocomposites (Ag/MMT/Cts BNCs) are described in terms of the initial concentrations of AgNO3. The mean diameters and standard deviation of Ag NPs in all of solid supports increased gradually with the increase of silver ions concentration. The external morphologies indicate that there are no noteworthy morphological distinctions between solid substrates and Ag NPs incorporated to them. The Ag NPs by the physical synthetic route were synthesized in the lamellar space of MMT/Cts utilising the UV-irradiation reduction method in the absence of reducing agent or heat treatment. The properties of Ag/MMT/Cts BNCs were studied as the function of UV-irradiation times. UV-irradiation disintegrated the Ag NPs into smaller size until a relatively stable size and size distribution were achieved. The silver nanocrystals were also synthesized by another physical method into the interlamellar space of MMT by using ƴ-irradiation in the absence of reducing agent or heat treatment. The properties of Ag/MMT NCs and the diameters of Ag NPs were studied as a function of ƴ-irradiation doses. The results from the UV-visible spectroscopy and TEM demonstrated that increasing the ƴ-irradiation doses enhanced the concentration of Ag NPs. In addition, the particle size of Ag NPs gradually increased from 1 until 20 kGy. When the ƴ-irradiation doses increased from 20 to 40 kGy, the particle diameters decreased suddenly as a result of the induced fragmentation for Ag NPs. Moreover silver/poly(lactic acid) nanocomposites (Ag/PLA NCs) films were investigated, while Ag NPs were synthesized into the biodegradable PLA as a polymeric matrix and stabilizer in the presence of sodium borohydride as a chemical reduction agent in diphase solvent. In all preparation, MMT, talc and zeolite were used as the inorganic solid supports and poly(lactic acid) was used as organic polymeric matrix. The silver nitrate, chitosan, and sodium borohydride were used as the silver precursor, natural and biodegradable polymeric stabilizer, and the reduction agent respectively. The crystalline structure of Ag NPs for all of samples, average size and size distributions, surface plasmon resonance, surface morphology, and functional groups were studied using X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-visible spectroscopy (UVvis), scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) respectively. The XRD analysis confirmed that the crystallographic planes of the silver crystals were the face-centred cubic (fcc) types. The UV-visible absorption spectra showed the peaks characteristic of the surface plasmon resonance (SPR) bonds of Ag NPs. The antibacterial activities of Ag NPs were investigated against Gram-negative and Gram-positive bacteria by the disk diffusion method using Mueller-Hinton Agar (MHA) at different sizes and amounts of Ag NPs. Results show that the antibacterial activity of Ag NPs can be modified with the particle size of Ag NPs

Effect of heat treatment on thermal diffusivity of Zn/Al layered double hydroxide synthesized using photoflash technique

Thermal diffusivity of zinc-aluminum layered double hydroxides was synthesized at different molar ratio of zinc and aluminum salts in the pH=7 and measured by using polyvinlidene diflouride (PVDF) by photoflash technique. The samples were prepared using Zn(NO3)2 and Al(NO3)3 solutions by drop wise addition of NaOH solution with vigorous stirring under nitrogen atmosphere. The samples then heat treated by control an electrical furnace from 200 to 600 °C for 5 hours. Thermal diffusivity was increased for all samples after sintering. The samples were studied by powder x-ray diffraction method, Fourier transform infrared (FTIR), scanning electron microscope (SEM) and thermal diffusivity. Our results indicate the very different role of sintering in the structure and thermal diffusivity of samples

Application of Artificial Neural Network (ANN) for prediction diameter of silver nanoparticles biosynthesized in Curcuma longa extract

In this study silver nanoparticles (Ag-NPs) are biosynthesized from silver nitrate aqueous solution through a simple and eco-friendly route using Curcuma longa (C. longa) tuber powder extracts which acted as a reductant and stabilizer simultaneously. Characterizations of nanoparticles are done using X-ray diffraction (XRD) and transmission electron microscopy (TEM). We present an artificial neural network (ANN) approach is used to model the size of Ag-NPs as a function of the volume of C. Longa extraction, temperature of reaction, stirring time and volume of AgNO3. The suitable ANN model is found to be a network with two layers that first layer has 10 neurons and second layer has 1 neuron. This model is capable for predicting the size of Ag-NPs synthesized by green method for a wide range of conditions with a mean absolute error of less than 0.01 and a regression of about 0.99. Based on the presented model it is possible to design an effective green method for obtain Ag-NPs, while minimum received materials are used and minimum size of Ag-NPs will be obtained. Also simulation of the process is performed using ANN media. According to the model’s results, the volume of C. Longa extraction, temperature of reaction, and volume of AgNO3 about 18 mL, 30 °C and 2 mL are chosen as the optimum size of Ag-NPs, respectively. Results obtained reveal the reliability and good predicatively of neural network model for the prediction of the size of Ag-NPs in green method

Synthesis and characterization of Cu@Cu2O core shell nanoparticles prepared in seaweed Kappaphycus alvarezii media

This study reports a synthesis of Cu@Cu2O core shell nanoparticles (NPs) in Kappaphycus alvarezii (K. alvarezii) media via a chemical reduction method. The nanoparticles were synthesis in an aqueous solution in presence of K. alvarezii as stabilizer and CuSO4.5H2O precursor. The synthesis proceeded with addition of NaOH as pH moderator, ascorbic acid as antioxidant and hydrazinium hydroxide as the reducing agent. The resulting nanoparticles characterized by using UV–vis spectrum, X-ray diffraction, Transmission electron microscopy, Fourier transform infrared (FT-IR) and atomic force absorption (AFM). The UV-visible spectra indicate to peaks at 590 nm and 390 which confirmed the formation of Cu@Cu2O-NPs. The XRD used in analysis of the crystal structure of nanoparticles. The morphology and structure of the K. alvarezii/Cu@Cu2O-NPs were investigated by TEM and AFM. The average size of Cu@Cu2O-NPs obtained were around 53nm that confirmed by using X-ray diffraction, TEM and AFM. The Fourier transform infrared FT-IR)spectrum suggested the complexation present between K. alvarezii and Cu@Cu2O-NPs

Synthesis of talc/Fe3O4 magnetic nanocomposites using chemical co-precipitation method.

The aim of this research was to synthesize and develop a new method for the preparation of iron oxide (Fe3O4) nanoparticles on talc layers using an environmentally friendly process. The Fe3O4 magnetic nanoparticles were synthesized using the chemical co-precipitation method on the exterior surface layer of talc mineral as a solid substrate. Ferric chloride, ferrous chloride, and sodium hydroxide were used as the Fe3O4 precursor and reducing agent in talc. The talc was suspended in deionized water, and then ferrous and ferric ions were added to this solution and stirred. After the absorption of ions on the exterior surface of talc layers, the ions were reduced with sodium hydroxide. The reaction was carried out under a nonoxidizing oxygen-free environment. There were not many changes in the interlamellar space limits (d-spacing=0.94-0.93nm); therefore, Fe3O4 nanoparticles formed on the exterior surface of talc, with an average size of 1.95-2.59nm in diameter. Nanoparticles were characterized using different methods, including powder X-ray diffraction, transmission electron microscopy, emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. These talc/Fe3O4 nanocomposites may have potential applications in the chemical and biological industries

Artificial intelligence in numerical modeling of silver nanoparticles prepared in montmorillonite interlayer space

Artificial neural network (ANN) models have the capacity to eliminate the need for expensive experimental investigation in various areas of manufacturing processes, including the casting methods. An understanding of the interrelationships between input variables is essential for interpreting the sensitivity data and optimizing the design parameters. Silver nanoparticles (Ag-NPs) have attracted considerable attention for chemical, physical, and medical applications due to their exceptional properties. The nanocrystal silver was synthesized into an interlamellar space of montmorillonite by using the chemical reduction technique. The method has an advantage of size control which is essential in nanometals synthesis. Silver nanoparticles with nanosize and devoid of aggregation are favorable for several properties. In this investigation, the accuracy of artificial neural network training algorithm was applied in studying the effects of different parameters on the particles, including the AgNO3 concentration, reaction temperature, UV-visible wavelength, and montmorillonite (MMT) d-spacing on the prediction of size of silver nanoparticles. Analysis of the variance showed that the AgNO3 concentration and temperature were the most significant factors affecting the size of silver nanoparticles. Using the best performing artificial neural network, the optimum conditions predicted were a concentration of AgNO 3 of 1.0 (M), MMT d-spacing of 1.27 nm, reaction temperature of 27°C, and wavelength of 397.50 nm