Synergistic effects of graphene oxide grafted chitosan & decorated MnO2 nanorods composite materials application in efficient removal of toxic industrial dyes

Abstract

In this study, we designed a heterogeneous graphene oxide (GO) grafted on chitosan decorated with MnO2 nanorods (α-MnO2NRs/GO-Chit) composite materials and its ability to remove the cationic and anionic toxic dyes from wastewaters were analysed. The synthesised materials presented an effective stabilization of active MnO2 nanorods (NRs) on the GO-Chit surface. The synthesised materials were detailed characterised by several spectroscopic and microscopic techniques such as, FT-IR, P-XRD, SEM, TEM, Raman, TGA, XPS, BET, CO2-TPD and UV–Visible analysis. In addition, α-MnO2NRs/GO-Chit material is successfully applied in removal of industrial ionic dyes such as amido black 10B (AB) and methylene blue (MB), respectively. The dye adsorption experiments confirmed that the GO-Chit/α-MnO2 NRs material exhibited remarkably high adsorption capacity in efficient removal of cationic dye methylene blue (MB) and anionic dye amido black 10B (AB). The maximum MB dye removal (97%) process completed in 24 min at C0 = 30 mg·L−1, but in the case of AB the maximum dye removal (80%) process was reached in 700 min. Over GO-Chit/α-MnO2 NRs hybrid material, a maximum theoretical monolayer adsorption (qmax values is 328.9 mg g−1) of MB was calculated from the Langmuir isotherm equation. In case MB, a faster adsorption and 2.18 times maximum adsorption capacity was achieved than that of AB10 dye. The enhanced adsorption over α-MnO2NRs/GO-Chit is due to the increased surface functionalities (i.e., oxygen-containing groups), high basicity and strong electrostatic forces between MnO2 nanorods and GO-Chit. Furthermore, α-MnO2NRs/GO-Chit hybrid material displayed good stability after 10 successive adsorption tests.