The chemical and structural analysis of graphene oxide with different degrees of oxidation

Application of silica nanoparticles as fillers in the preparation of nanocomposite of polymers has drawnmuch attention, due to the increased demand for new materials with improved thermal, mechanical, physical, and chemical properties. Recent developments in the synthesis of monodispersed, narrow-size distribution of nanoparticles by sol-gel method provide significant boost to development of silica-polymer nanocomposites. This paper is written by emphasizing on the synthesis of silica nanoparticles, characterization on size-dependent properties, and surface modification for the preparation of homogeneous nanocomposites, generally by sol-gel technique. The effect of nanosilica on the properties of various types of silica-polymer composites is also summarized.

/pdf/synthesis-of-silica-nanoparticles-by-sol-gel-size-dependent-4pexez08bs.pdf

Synthesis of silica nanoparticles by sol-gel: size-dependent properties, surface modification, and applications in silica-polymer nanocomposites — a review

Systemic effects of smoking.

We report selective ionic transport through controlled, high-density, subnanometer diameter pores in macroscopic single-layer graphene membranes. Isolated, reactive defects were first introduced into the graphene lattice through ion bombardment and subsequently enlarged by oxidative etching into permeable pores with diameters of 0.40 ± 0.24 nm and densities exceeding 1012 cm–2, while retaining structural integrity of the graphene. Transport measurements across ion-irradiated graphene membranes subjected to in situ etching revealed that the created pores were cation-selective at short oxidation times, consistent with electrostatic repulsion from negatively charged functional groups terminating the pore edges. At longer oxidation times, the pores allowed transport of salt but prevented the transport of a larger organic molecule, indicative of steric size exclusion. The ability to tune the selectivity of graphene through controlled generation of subnanometer pores addresses a significant challenge in the dev...

/pdf/selective-ionic-transport-through-tunable-subnanometer-pores-1jya7cyr05.pdf

Selective ionic transport through tunable subnanometer pores in single-layer graphene membranes.

Water pollution is one of the most pervasive problems afflicting people throughout the world, while adsorption is the most widely used method to remove the contaminants from water. Here, in this paper, we report an eco-friendly graphene oxide–chitosan (GO–CS) hydrogel as a new type of adsorbent for water purification. The GO–CS hydrogels were prepared via self-assembly of GO sheets and CS chains. A three-dimensional network composed of GO sheets crosslinked by CS was found in GO–CS hydrogels. The GO–CS composite hydrogels showed high adsorption capacity towards different contaminants, including cationic and anionic dyes, as well as heavy metal ions. The mechanism of the dye adsorption was investigated with a spectral method, and an electrostatic interaction was found to be the major interaction between ionic dyes and the hydrogel. The influence of the hydrogel composition on the adsorption capacity towards different adsorbates was also studied. Finally, it was demonstrated that the GO–CS hydrogel can be used as column packing, to fabricate a column for water purification by filtration.

Graphene oxide–chitosan composite hydrogels as broad-spectrum adsorbents for water purification

Adsorption of organic molecules on silica surface.

http://dspace.nitrkl.ac.in/dspace/bitstream/2080/871/1/oxidation.pdf

Sukalyan Dash

Papers

Adsorption of organic molecules on silica surface.

Oxidation by permanganate: synthetic and mechanistic aspects

An investigation of the origin and growth of annealing twins

Clouding behaviour in surfactant systems.

Sorption on eggshell waste--a review on ultrastructure, biomineralization and other applications