Narcisa Vrinceanu

Zinc oxide application in the textile industry: surface tailoring and water barrier attributes as parameters with direct implication in comfort performance

The present study focuses on surface tailoring and water barrier attributes of zinc oxide (ZnO)-polyester composite textile materials. The surface properties, such as surface topography and roughness, composite compositions as well as thermal stability of ZnO-100% polyester textile composite materials treated through a padding process with different concentrations of ZnO dispersions as active agent in water and methanol were studied. The results show that 3% ZnO-textile composite material have enhanced water barrier properties compared with the other compositions; a fact which promises improved properties in terms of comfort. ZnO modification of polyester surfaces leads to a dramatic decrease in their thermal stability.

Preparation and thermal stability of Al2O3-clay and Fe2O3-clay nanocomposites, with potential application as remediation of radioactive effluents

In the last years metal/clays, aluminosilicates with properties and characteristics of microporous materials, have received more attention, due to the possibility of their use as matrix for nanoparticles encapsulation and stabilization processes. Some types of clays were comparatively evaluated for treating the simulated radioactive wastewater. The raw clay from Valea Chioarului Romania and its pillared forms with Al, Fe, pillars for decontamination of waste-waters with medium and low radioactivity were used. Characterization of the obtained materials was carried out using techniques such as X-ray diffraction, Fourier transform infrared spectroscopy, BET analyses and thermogravimetric analysis (DTG-TG), respectively. Also, the thermal stability of nanocomposites was highly superior to native clay due to the presence of the well-dispersed clay nanolayer, which has a barrier property in a composite system. Clay nanocomposite sample materials were obtained with good thermal stability after calcination. Clay nanocomposites samples were evaluated for remediation of radioactive effluents by treating the radioactive wastes streams. The ion-exchange characteristics and the abilities to uptake radioisotopes of indigene clay from Valea Chioarului area-Romania were examined. The results showed that the precursor used in sample preparation influenced the structural and textural properties of nanocomposites and also capability of prepared modified clay samples by pillaring to be potential candidates for use in connection with environmental protection, remediation of radioactive effluents, respectively.

Zinc oxide-linen fibrous composites: morphological, structural, chemical and humidity adsorptive attributes:

The main result and characterizing aspect of the research consists of the effectiveness of novel ZnO-linen fibrous composites synthesized by means of hydrothermal deposition of zinc oxide onto linen fibers, with the assistance of two surfactants. This has a direct implication on the relationship between the morphological, structural and chemical attributes and water vapor sorption-desorption behavior. Methodology consists of the hydrothermal synthesis of zinc oxide onto linen fibrous substrates previously grafted with MCT-β-CD (MonoChloroTriazinyl–β-CycloDextrin) via a hydrothermal process. The morphological, structural and chemical properties of the samples were examined, in terms of a co-assisted investigation system: SEM images for the morphology, EDX analysis for surface composition, FTIR spectroscopy and X-ray diffractometry for structural samples features. Dynamic vapor sorption (DVS) analysis will complete this study. According to the results provided by the characterization technique, the uniformity of the fabric coated with ZnO powder hydrothermally synthesized with assistance of CTAB (Cetyl TrimethylAmmonium Bromide) is better than that of ZnO powder hydrothermally synthesized in the presence of Pluronic P123 and possesses good washing fastness. X-ray diffraction results have indicated that the composites exhibited a more ordered structure and higher water vapor sorption-desorption capacity (obtained by DVS analysis) compared with those of the reference fibrous linen supports.

Research Regarding a Correlation Core–Shell Morphology–Thermal Stability of Silica–Silver Nanoparticles

Silica nanoparticles repeatedly inhaled lead to acute and chronic lung inflammation and finally to pulmonary fibrosis and lung cancer, people with chronic respiratory diseases like asthma or allergic rhinitis being even more susceptible to their toxic effects. In order to reduce these above-mentioned toxic effects, the aim of this study was to engineer the environmental silica nanoparticles with silver and subsequent thermal treatment. Nanometer-sized and spherical silica particles were synthesized in a homogeneous state, using a simple one-pot chemical method. An applicable approach resulted in silver particles forming over the surface of the silica. The outcome was materialized in extremely small silver particles attached to silica core particles. Playing their well-known decisive role, precursors and catalysts effectively controlled the size of silver and silica particles. The synchronized structure of the synthesized particles was revealed by the electrostatic repulsion among the silica spheres and the electrostatic attraction between silica spheres and silver particles. The morphological images are revealed by means of a scanning electron microscope. The formation of silver–silica composite particles was confirmed by using infrared spectroscopy and X-ray photoelectron spectroscopy analysis. Following thermal analysis, the results concerning the thermal stability of the prepared particles provided higher temperature applications.

Zinc Oxide — Linen Fibrous Composites: Morphological, Structural, Chemical, Humidity Adsorptive and Thermal Barrier Attributes

Nanoparticles are extremely reactive, due to their high surface energy, and most systems undergo aggregation without protection of their surfaces. To eliminate or minimize generated waste and implement sustainable processes, recently green chemistry and chemical processes have been emphasized for the preparation of nanoparticles [2]. Much attention is now being focused on polysaccharides used as the protecting agents of nanoparticles. As stabilizing agent soluble starch has been selected and as the reducing agent in aqueous solution of AgNO3 for silver nanoparticle growth, and a-D-glucose, has been elected. To maintain noble metal (platinum, palladium and silver) nanoparticles in colloid suspension, Arabinogalactan has been used as a novel protecting agent for [3]. Synthesized platinum, palladium and silver nanoparticles with narrow size distribution have been achieved by using porous cellulose

Coloristic and antimicrobial behaviour of polymeric substrates using bioactive substances

A major concern in reducing microbial contamination of healthcare and hygiene products motivated us to seek viable alternatives in order to create such barriers. The antimicrobial and anti-oxidant effects of natural extracts are well-known, their application onto polymeric supports is still challenging in terms of investigation. To our knowledge, the method of natural dyeing of different polymeric substrates using bioactive substances derived from black currant and green walnut shells, in conjunction with biomordants, and their long term effects have not been very consistently reported. The main objective of the study is based on the comparative study of different polymeric fibrous substrates dyed by means of laboratory scaled classic methodology with extracts from black currant fruits and green walnut shells, with the assistance of conventional and biomordants (copper sulphate, citric and tannic acids). The assistance of biomordant in the dyeing process seems to conduct to improved synergetic colouring and antibacterial performances. The main results demonstrated that the extract of green walnut shells reinforced by the biomordants solutions expressed the best antimicrobial behaviour. The present research is a milestone in the identification of potential technological alternatives applied in dyeing of synthetic and natural textile supports, quantified and controlled by antimicrobial response correlated with colorimetric features.

Waste-water management by a comparative research of photocatalytic performance belonging to coupled ZnO/SnO2 nanocomposites against degradation of textile dyes

Coupled ZnO/SnO2 nanocomposites were successfully prepared with different molar ratios (1/1-1/10) using a homogeneous co-precipitation method. The structural properties of the obtained oxides were evaluated using different techniques: N2 sorption, Infrared spectroscopy, UVDR spectroscopy for solid compounds and scanning electron microscopy (SEM). The photocatalytic activity of the samples was tested for the bleaching of eosin Y. The photocatalytic process occurs under the illumination of an UV lamp, emitting light at 254 nm. The influence of the wavelength and the ZnO:SnO2 molar ratio over the photocatalytic efficiency was studied.

Precursor concentration effect on structure and morphology of ZnO for coatings on fabric substrates

Abstract ZnO is a versatile functional material that has a diverse group of growth morphologies. By controlling the growth kinetics, it is possible to change the growth behavior of ZnO structures. Growth of ZnO structures can be achieved in a cheaper way at low temperature using chemical growth techniques such as aqueous chemical growth, nonaqueous solution growth, sol gel and spray deposition. Up to date, there are quite few reports in the literature presenting state of art approaches of use of ZnO material onto textile substrates for several applications as antibacterial, deodorizing and UV protection, and none regarding any systematic approach of direct growth and optimization with respect to the textile support. The successful exploitation of ZnO particles for use in various technological applications requires the development of techniques for controlling its photocatalytic activity. The present contribution presents a study of precursor concentration effect on structure and morphology of ZnO for coatings on fabric substrates. ZnO particles were obtained by direct growth onto the respective substrate by aqueous chemical growth using suitable precursors for each growth and then characterized regarding their appearance, size and structure using microscopic techniques and X-ray diffraction.