Microwave synthesis and adsorption performance of a novel crosslinked starch microsphere

•CSM was synthesized in a microwave-assisted inversed emulsion system.•The adsorption of methyl violet on CSM was exothermic and spontaneous.•The adsorption process followed the pseudo-second-order kinetics.•The isothermal data obeyed the Langmuir model.•pH variations did not significantly affect the adsorption of methyl violet onto CSM. A new crosslinked starch microsphere (CSM) was synthesized in a microwave-assisted inversed emulsion system with soluble starch (ST) as a raw material, MBAA as a crosslinker, and K2S2O8–NaHSO3 as an initiator. The synthesized starch microsphere was characterized and examined by scanning electron microscope (SEM), FTIR spectroscopy and adsorption isotherms of N2 at 77K. Adsorption performance was investigated in methyl violet solution. The results showed that the maximum adsorption capacity for MV was 99.3mg/g at 298K, and the adsorption fitted pseudo-second-order kinetic model well with correlation coefficients greater than 0.99. The isothermal data obeyed the Langmuir model better compared to Freundlich model and Tempkin model, and the adsorption was exothermic and spontaneous. pH variations (2.0–10.0) did not significantly affect the adsorption of MV onto CSM.