Three polysaccharide- graphene oxide composite materials (PS-GO) were synthesized from graphene oxide (GO) and natural polysaccharides, which compounds were tested for removal of organic dyes from aqueous solutions. These adsorbents were characterized by Fourier transform infrared spectroscopy (FT-IR), Raman spectrometer, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), N2 adsorption-desorption isotherms and UV–vis spectrum. The adsorption properties of PS-GO towards four organic dyes were investigated along with measured effects on adsorption by initial concentration, temperature, contact time and pH value. Resulting adsorption isotherms, thermodynamics and kinetics were analyzed systematically. In these tests, PS-GO composite materials were found to be more efficient than as-prepared GO as adsorbents for the removal of both cationic and anionic organic dyes.

A series of environmental-friendly adsorbents, κ-carrageenan/graphene oxide gel beads (κ-Car/GO GBs), were synthesized from κ-carrageenan and graphene oxide via a simple method. The composition and morphology of these gel bead adsorbents were characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, scanning electron microscopy, etc. The adsorption ability of κ-Car/GO GBs was investigated by measuring the removal of methylene blue (MB) from aqueous solutions. The effects of the initial dye concentration, adsorption time, temperature and pH value were evaluated. The results of the adsorption experiments were consistent with the Langmuir model, while the adsorption kinetic data were fit with a pseudo-second-order model. The maximum adsorption capacity of κ-Car/GO GBs for MB is 658.4 mg/g at 25 °C, which barely declined even after five cycles. Hence, the κ-Car/GO GBs are outstanding adsorbents with high adsorption capacity and excellent regeneration ability. Furthermore, the gel bead adsorbents could be easily separated from aqueous solutions after adsorption using a simple filtration method.Download high-res image (62KB)Download full-size image

Two novel anion sensors, methyl 4-(5-(5-chloro-2-hydroxyphenyl)-1,3,4-oxadiazol-2-yl) benzoate (L1) and methyl 4-(5-(2-hydroxyphenyl)-1,3,4-oxadiazol-2-yl) benzoate (L2) were reported. Their spectroscopic and colorimetric properties in CH2Cl2/CH3CN (1:2, v/v) solution for F− sensing were investigated by naked-eye, UV–vis, and fluorescence measurements. Both molecules with coplanar structure possess adjacent phenolic hydroxyl and 1,3,4-oxadiazole units, resulting in a sufficiently strong intramolecular hydrogen bond to hinder the association of most anions, but not F−, with phenolic hydroxyl hydrogen. They displayed the same color changes from colorless to yellow but different optical shifts upon addition of F−.