Multifunctional Nanocomposite Cellulose Fibers Doped in Situ with Silver Nanoparticles

This paper presents a method for the preparation of nanocomposite cellulose fibers doped with silver nanoparticles (AgNPs), as well as the effect of silver nanoparticles on the structure and properties of fibers. The fibers were obtained by an environmentally friendly method using N-Methylmorpholine N-oxide (NMMO) as a solvent, in a non-polluting closed system. Doping with silver nanoparticles was carried out as a direct (in situ) reduction of Ag+ ions in the presence of a stabilizing agent during the preparation of the spinning solution. SEM images of the surface and cross section of the fibers showed that the distribution of nanoparticles in the fibers’ volume was uniform. The fibers exhibited very good antibacterial properties in relation to Staphylococcus aureus, Escherichia coli, Acinetobacter baumannii, and Candida albicans. Flammability analysis showed that the fibers were subjected to a one-stage combustion process and that the silver nanoparticles reduced the heat release rate (HRR) of the fibers by 36%. TG studies showed that the modification of cellulose fibers with silver nanoparticles promoted the formation of mill scale in the combustion of fibers, which was directly related to the reduction of flammability. Tests of the electrical properties showed that the linear resistance of cellulose fibers containing 3 wt % silver was 108 Ω/cm.

An unexpected lanthanum chloride carbonate hydrate: synthesis, crystal structure, vibrational spectra and thermal degradation of LaCl[CO3]·3H2O

Microcrystalline powders of LaCl[CO3]·3H2O were precipitated and isolated from stoichiometric aqueous solutions of LaCl3·7H2O and Na2[CO3]·10H2O. This confirmed the surprising emergence of corresponding single crystals during a reaction of equimolar aqueous solutions of LaCl3·7H2O and Na[N3] under ambient conditions by the uptake of atmospheric CO2. According to the X-ray structure analysis of colorless, transparent and rectangular single-crystals, LaCl[CO3]·3H2O adopts an orthorhombic structure, space group Pbca with the unit-cell parameters a=856.82(5), b=1598.57(9) and c=967.68(6) pm for Z=8. The tenfold coordination polyhedron around La3+ consists of two monodentate as well as two bidentate [CO3]2− anions together with three oxygen atoms from coordinating water molecules and one chloride anion. According to DSC/TG studies and X-ray powder diffraction, LaCl[CO3]·3H2O loses first its water and then carbon dioxide under thermal treatment up to 900°C to leave LaOCl behind. Vibrational infrared and Raman spectra confirmed the presence of H2O and [CO3]2− in LaCl[CO3]·3H2O and its stepwise degradation at elevated temperatures.

Effects of Different Raw Materials in the Synthesis of Boehmite andγ- andα-Alumina

Two alumina polymorphs, the metaestableγ-Al2O3and the stableα-Al2O3, were obtained from thermal treatment of the precursorγ-AlOOH (boehmite). This precursor was prepared by a precipitation method employing different raw materials in order to study their effect on the synthesis process and several characteristics of the materials, such as the crystallite size, the thermal behavior, and the surface area. Aluminum chloride (AlCl3·6H2O) and an aluminum waste were used as the source of aluminum. A 1 M NaOH solution and a 1 M n-butylamine solution were used as alkalizing agents, due to their strong and weak alkaline characteristics, respectively. The XRD profiles of the boehmites obtained from waste show lower crystallinity than samples obtained from aluminum chloride. The content of water, from TG studies, was higher in the samples obtained from waste, which fit well with the smaller crystallite size. The use of n-butylamine as alkalizing agent favors the formation ofγ-alumina with higher surface area (177.2 cm2 g−1, for aluminum waste, and 159.4 cm2 g−1, for aluminum pure reagent). The temperature of transformation from gamma to alpha, from DTA results, is higher for samples obtained from the waste, and accordingly the presence of impurities in the waste stabilizes the metastable alumina phase.

A Novel Cyanide-Free Gold Complex: [Au(tu)2 ]SCN H2O

A novel aurous complex containing thiourea and thiocyanate as the mixed ligands is synthesized by the ISRC method in this paper. Its formula is determined as [Au (tu)2 ]SCN H2O by elemental analysis. The electrochemistry studies show it is a typical ionic compound and its conductivity reaches 13×10-4 Sm2mol-1. TG studies and related stability tests reveal the compound is excellently stable. By using single factors experiments the optimal plating index has been gotten and they are: pH=1.5~3.5, [A =1.5~2.5 g/L, temperature 30~50°C and plating time 10 minutes respectively. It is a competitive gold complex and will be find a wide application in electroplating, chemical deposition, ceramic decoration and other related areas.

Non-Isothermal Decomposition of 2-(2-Hydroxybenzylideneamino)-3-phenylpropanoic Acid in Nitrogen Atmosphere

The non-isothermal decomposition properties of 2-(2-hydroxy- benzylideneamino)-3-phenylpropanoic acid [HBAPPA] have been studied using microanalysis, FT-IR, UV, DTA, DTG and TG techniques. The TG studies were carried out at different heating rates of 10, 15 and 20 K/min. The Schiff base decomposed in three stages. The kinetic parameters were deduced for each stage. A probable mechanism has been proposed for the decomposition process.