Vinyl alcohol

About: Vinyl alcohol is a research topic. Over the lifetime, 13839 publications have been published within this topic receiving 315464 citations. The topic is also known as: Ethenol & Hydroxyethene.

Mechanisms of Lead Adsorption on Chitosan/PVA Hydrogel Beads

Abstract: Removal of lead from aqueous solution with chitosan/PVA (poly(vinyl alcohol)) hydrogel beads was studied in batch adsorption experiments at various solution pH values (2−7.6). Lead adsorption on chitosan/PVA beads was found to be strongly pH-dependent and displayed a maximum uptake capacity at pH around 4 and a minimum at pH about 6.4. ζ-Potential study indicated that chitosan/PVA beads possessed positive ζ-potentials at pH 6.3. Hence, adsorption occurred even though the interaction between lead and chitosan/PVA beads was electrostatically repulsive at pH < 6.3. Complexation, ion exchange, and electrostatic interaction are all believed to play a role in lead adsorption on chitosan/PVA beads, but the relative importance of each of these mechanisms varies with solution pH values. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy spectra suggested that lead adsorption was mainly through interactions with the N atoms in chitosan in the pH rang...

Fabrication and Characterization of Silver−Polyvinyl Alcohol Nanocomposites

Abstract: The influence of silver (Ag) nanoparticles on the properties of poly(vinyl alcohol) (PVA) was investigated. The nanocomposite was prepared by mixing a colloidal solution consisting of silver nanoparticles with a water solution of PVA in appropriate ratios. Composite films with different contents of inorganic phase were obtained after solvent evaporation. The contents of the inorganic phase in the nanocomposites were determined by using atomic absorption spectroscopy (AA) for silver, and were found to be 0.19, 0.33, and 0.73 wt %. Transmission electron microscopy (TEM) of the nanocomposite films revealed the presence of Ag particles with average diameter of 20 nm. Comparison of the thermal properties of the pure polymer and the nanocomposite films showed that the thermal stability is improved by about 40 °C, and the glass transition temperature is shifted to a higher temperature up to 20 °C for the highest content of the nanofiller. An increase in Young's modulus and strength of the nanocomposite was also ...

Facile In Situ Synthesis of Noble Metal Nanoparticles in Porous Cellulose Fibers

Abstract: In situ synthesis of noble metal (Ag, Au, Pt, Pd) nanoparticles was carried out under ambient conditions in porous cellulose fibers as nanoreactors. Particles of less than 10 nm were readily prepared using the described approach, and monodisperse nanoparticles were obtained under an optimized concentration of the metal precursor solution. The nanoporous structure and the high oxygen (ether and hydroxyl) density of the cellulose fiber constitute an effective nanoreactor for in situ synthesis of metal nanoparticles. The nanopore is essential for incorporation of metal ion and reductant into cellulose fibers as well as for removal of unnecessary byproducts from fibers. This was endorsed by negligible adsorption of metal ion onto nonporous films of poly(vinyl alcohol) and starch. The ether oxygen and the hydroxyl group not only anchor metal ions tightly in cellulose fibers via ion−dipole interactions, but they also stabilize metal nanoparticles by strong bonding interaction with their surface atoms. The prepa...