Ultrafast and selective adsorption of anionic dyes with amine-functionalized glucose-based adsorbents

Synthesis of biomass-based carbonaceous adsorbents with high adsorption performance, reusability, environmental-friendliness as well as low cost for water treatment remains a challenge. In this study, a glucose-based amine-functionalized carbon microsphere (AF-CMS) was synthesized via hydrothermal method and amine functional modification for the removal of organic dye. The results of materials characterization demonstrated an efficient amine functionalization of AF-CMS with a high nitrogen loading of 25.0 wt.% and strong positive charge under acidic conditions. Batch adsorption studies showed that the maximum adsorption capacities of AF-CMS for methyl orange (MO) and tartrazine (TTZ) were up to 1487.29 and 699.30 mg g−1, and the adsorption equilibrium was reached within 30 min with the 500 mg L−1 of dye solution. It could also quickly and completely capture dye molecule within 8 min for the TTZ dye solution of 100 mg L−1. The adsorption data of AF-CMS on anionic dyes was correlated with the pseudo-second-order kinetic and the Langmuir isotherm model. The adsorption capacity of AF-CMS for MO and TTZ dye still reached 1234.55 mg g−1 (83.01% of Qmax) and 618.65 mg g−1 (88.47% of Qmax), respectively, after five cycles of regeneration. More importantly, superior adsorption selectivity was demonstrated by the investigation of mixture of anionic dye and cation dye. Comprehensive analysis revealed that the good adsorption performance of AF-CMS was contributed to the strong electrostatic interaction between dye molecular and amine groups. Based on its simple preparation, low cost and excellent adsorption properties, the AF-CMS possesses a promising candidate for separating organic dyes from wastewater.