Dang Van Phu

Preparation of colloidal silver nanoparticles in poly(N-vinylpyrrolidone) by γ-irradiation

Colloidal silver nanoparticles were prepared by γ-irradiating Ag+ in aqueous solution in the presence of 2% polyvinyl pyrrolidone (PVP) as stabilising agent and ethyl alcohol as free radical (OH•) scavenger. The saturated conversion dose of Ag+ into Ag was determined by UV–Vis spectroscopy and the silver nanoparticles size was characterised by transmission electron microscopy. The influence of Ag+ concentration (1–50 mM) on the saturated conversion dose and average diameter of silver nanoparticles was investigated. Results showed that the saturated conversion dose was from 8 to 48 kGy and the silver particles size was in the range of 6–21 nm for Ag+ concentration from 1 to 50 mM. The effect of PVP molecular weight on silver particles size was studied as well.

Gamma irradiation of cotton fabrics in AgNO3 solution for preparation of antibacterial fabrics

Silver nanoparticles (AgNPs) with diameter about 12 nm were immobilized on the surface of cotton fabrics by γ-irradiation of fabrics in the AgNO3 chitosan solution. Effects of absorbed dose, concentration of AgNO3 solution on immobilization of the AgNPs on fabrics were investigated. The optimal dose was selected to be 13.8 kGy and the suitable concentration of AgNO3 was 1.5mM in 1% chitosan solution. The content of AgNPs on fabrics was of 1,696 ± 80 mg/kg for these conditions. The presence of AgNPs on fabrics was confirmed from scanning electron microscopy (SEM) images and X ray diffraction (XRD) patterns. The antibacterial activity of AgNPs/cotton fabrics after 40 washings against Staphylococcus aureus and Escherichia coli was found to be 99.99%. In addition, the AgNPs fabrics were innoxious to the skin (k=0) after 1, 5, 10, 20, 30 and 40 washings by skin-irritation testing to animal (rabbit).

Synthesis and Investigation of Antimicrobial Activity of Cu2O Nanoparticles/Zeolite

Cuprous oxide (Cu2O) nanoparticles in zeolite A were synthesized by two steps: (i) ion-exchange of copper ions into the zeolite and (ii) reduction of copper ions in cages of the zeolite by hydrazine hydrate in base medium. The Cu2O nanoparticles/zeolite product was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX). The particle size of Cu2O nanoparticles was of 40 nm. The antibacterial activity of the as-synthesized Cu2O nanoparticles/zeolite against Escherichia coli was also investigated. Cu2O NPs/zeolite product can be favorably produced on large scale for water treatment and agricultural application as antimicrobial agent.

Synthesis of Gold Nanoparticles Stabilized in Dextran Solution by Gamma Co-60 Ray Irradiation and Preparation of Gold Nanoparticles/Dextran Powder

Gold nanoparticles (AuNPs) in spherical shape with diameter of 6–35 nm stabilized by dextran were synthesized by γ-irradiation method. The AuNPs were characterized by UV-Vis spectroscopy and transmission electron microscopy. The influence of pH, Au3

Effect of nanosilica/chitosan hybrid on leaf blast and blight diseases of rice in Vietnam

Nanosilica/chitosan (NSi/CTS) hybrid material was prepared using nanosilica (32.5 nm) from rice husk ash (RHA) and chitosan (CTS), and characterized by transmission electron microscopy (TEM), F ourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD). The obtained NSi/CTS was used for protection of rice leaf from blast disease ( Piriculariaoryzae ) and blight disease ( Xanthomonasoryzae ). Results indicated that foliar spraying of NSi/CTS with 100 ppm NSiand150 ppm CTS were effective against blast and blight diseases on rice ( Oryza spp.). The leaf blast disease index (DI) (1.49 %) and the blight DI (1.45 %) were significantly decreased compared with control of 8.08 % and 9.29 %, respectively at 14 th day after the first treatment. Thus, NSi/CTS hybrid material is promising to use for controlling plant diseases, particularly for rice.

Preparation and characterization of nanosilica from rice husk ash by chemical treatment combined with calcination

This work presented the results of the study on synthesis and characterization of nanosilica from rice husk ash (RHA). Nanosilica was obtained by calcination of HCl treated RHA at 700 o C for 2 h. X-ray diffraction (XRD) pattern showed only one peak at 2q ~22 o confirming the amorphous structure of nanosilica. The chemical composition assessed by energy dispersive X-ray spectroscopy (EDX) showed that the obtained nanosilica was of high purity. TEM image measured by transmission electron microscopy (TEM) revealed that the obtained nanosilica was in spherical morphology with the average diameter of about 45.5±7.2 nm. The particle size distribution of nanosilica determined by dynamic laser scattering (DLS) was of Gaussian mode. The FTIR spectrum indicated the presence of silanol and siloxane groups in nanosilica. Thus, the synthesized nanosilica can be used for application in different fields. Keywords. Rice husk ash, nanosilica, amorphous.

EFFECT OF NANOSILICA FROM RICE HUSK ON THE GROWTH ENHANCEMENT OF CHILI PLANT (Capsicum frutescens L.)

Nanomaterials hold great promise of improved plant disease resistance, controlled release of agro-chemicals, enhanced plant growth, etc. In t his study, the effect of nanosilica (10 – 30 nm) prepared from rice husk on the growth promotion of chili plant in green house was carried out. The experiment of nanosilica treatment by foli ar spraying was arranged in a factorial design with 3 replications at various nanosilica concentra tions of 0, 40, 60 and 100 ppm. Plant growth characteristics and chlorophyll content were assess ed. Results showed that the fresh weight, dry weight, and chlorophyll content increased with the tr atment of nanosilica. The optimal concentration of nanosilica was found to be of 60 p pm. Thus, treatment of nanosilica was beneficial in enhancing the growth of the chili pla nts.

Synthesis of silver nanoparticles deposited in porous ceramic by γ-irradiation

Silver nanoparticles (Ag nano) were deposited in porous ceramic (PC) that was functionalized with aminosilane (AS) agent (PC-AS-Ag nano) by gamma Co-60 irradiation of the PC-AS/Ag + mixture using polyvinylpyrrolidone (PVP) as stabilizer. Effect of dose on the formation of Ag nano was investigated. Characteristics of the nanocomposite material (PC-AS-Ag nano) were determined by ultraviolet visible spectroscopy (UV-Vis), X-ray diffraction (XRD), transmission electron microscopy (TEM) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Results indicated that Ag nano size was ~9 nm and the Ag nano content in PC-AS-Ag nano material was about of 341 ± 51 mg/kg at dose of 14-20 kGy. Thus, gamma Co-60 irradiation method has the advantage of creation of small Ag nanoparticles with fairly homogenous distribution in PC material.

DEGRADATION OF CHITOSAN BY γ-IRRADIATION OF CHITOSAN SWOLLEN IN HYDROGEN PEROXIDE SOLUTION

ABSTRACT Degradation of chitosan in swollen state with hydrogen peroxide solution (1–5% w/v) by γ-irradiation was investigated. Molecular weight (Mw) of irradiated chitosan samples was determined by gel permeation chromatography (GPC). Fourier transform infrared (FT–IR) spectra and X–ray diffraction (XRD) patterns were utilized to study the structure of degraded chitosan. Results showed that low Mw chitosan of ~30–45 kDa was efficiently prepared by γ–irradiation of chitosan (Mw 0 ~91.7 kDa) swollen in hydrogen peroxide solutions at low dose less than 20 kGy. The main structure as well as the degree of deacetylation of degraded chitosan was almost unchanged. Furthermore, the radiation degradation yield (G s ) was remarkably enhanced with the presence of H 2 O 2 as a sensitizer. Degradation of chitosan in swollen state with hydrogen peroxide solution by γ-irradiation is efficient for preparation of low Mw chitosan at low dose.