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

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In this study, we designed a heterogeneous graphene oxide (GO) grafted on chitosan decorated with MnO 2 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 MnO 2 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, CO 2 -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 C 0 = 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-MnO 2 NRs hybrid material, a maximum theoretical monolayer adsorption (q max 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-MnO 2 NRs/GO-Chit is due to the increased surface functionalities (i.e., oxygen-containing groups), high basicity and strong electrostatic forces between MnO 2 nanorods and GO-Chit. Furthermore, α-MnO 2 NRs/GO-Chit hybrid material displayed good stability after 10 successive adsorption tests. • A novel adsorbent MnO 2 nanorods decorated GO-Chit was prepared. • Synergistic effects of MnO 2 & GO-Chit delivered improved properties. • A high adsorption capacity and degradation rate in decoloration of wastewaters • MnO 2 NRs modified GO-Chit found to be efficient in removal of toxic dyes.