Graphene Oxide Synthesis and Applications

The chemicals used for graphene oxide synthesis were the following: natural graphite (Sigma Aldrich, St. Louis, Mo, USA), sulfuric acid (H₂SO₄, 95–97%, Merck, Darmstadt, Germany), potassium persulfate (K₂S₂O₈, Merck, Darmstadt, Germany), phosphorus (V) oxide (P₂O₅, Merck, Darmstadt, Germany), sodium nitrate (NaNO₃, Honeywell and Sigma-Aldrich, Gurgaon, India), potassium permanganate (KMnO₄, Merck, Darmstadt, Germany), hydrogen peroxide (H₂O₂, Merck, Darmstadt, Germany), hydrochloric acid (HCl, 36~38%, Merck, Darmstadt, Germany) and double-distilled water. TiO₂ P25 nanoparticles from Degussa and SiO₂ Aerosil 200 from Evonik (Essen, Germany) were used for the preparation of mixed TiO₂-SiO₂ powder. Acetylacetone and ethanol as organic dispersing agents were purchased from Merck, Darmstadt, Germany and Fluka. Organosilicon compounds namely, octamethylcyclotetrasiloxane, D4 and decamethylcyclopentasiloxane and D5 and biodegradable ethyl-lactate (Et-L) solvent were purchased from Alfa Aesar, Kandel, Germany. Alginic acid sodium salt (NaAlg) and gum rosin (GRos) were obtained from Aldrich, Norwich, United Kingdom and Aveiro, Portugal. Calcium chloride (CaCl₂, Alfa Aesar, Kandel, Germany) was used to promote physical crosslinking and form water-insoluble calcium alginate (CaAlg) on cotton and leather surface.
Bleached 100% cotton woven fabric with the weight of 168 g/m² was used for all experiments. The sheepskin leather surfaces were finished according to the classical technologies by spraying a base coat of acrylic resins with water-based casein pigment and a topcoat of water-based nitrocellulose emulsion [25 (link)]. The cotton and leather materials were provided by the National Research Institute for Leather and Textiles, Bucharest, Romania.