Functionalization of 4-aminothiophenol and 3-aminopropyltriethoxysilane with graphene oxide for potential dye and copper removal

In this work, 4-aminothiophenol and 3-aminopropyltriethoxysilane were firstly used to functionalize graphene oxide (GO) in order to promote the sorption efficiencies of methylene blue (MB) and copper (Cu2+). Characterization experiments illustrated that sulfydryl group (-SH) and amino group (-NH2) were existed onto 4-aminothiophenol modified GO (GO-SH) and 3-aminopropyltriethoxysilane modified GO (GO-N), respectively. Adsorption isotherm results showed that the maximum adsorption capacities of MB by GO-SH and GO-N were 763.30 and 676.22 mg/g, which was much higher than original GO 455.95 mg/g. For Cu2+ adsorption, the maximum adsorption capacities by GO-SH and GO-N were 99.17 and 103.28 mg/g, suggesting that the engineered GO exhibited greater Cu2+ sorption ability than original GO 32.91 mg/g. Both MB and Cu2+ removal rates increased with pH and adsorbent dosage increased, while the sorption rates weakly reduced with increasing ionic strength. The modification by -SH and -NH2 would not only increase the sorption sites, but also cause chelation with heavy metals, and thus improving the sorption capacities of MB and Cu2+. (C) 2016 Elsevier B.V. All rights reserved.