Starch Nanocrystals Grafted with Epichlorohydrin Dimethylamine for Methyl Blue Dye Removal

In this paper, modified starch nanocrystals (SNCs) are prepared successfully by grafting the epichlorohydrin-dimethylamine copolymer (PA) onto oxidized starch nanocrystals (OSNCs). The material is used as an adsorbent to deal with the methyl blue (MB) dye. The OSNCs-PA is characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and Scanning electron microscopy. The zeta potential of OSNCs-5.0%PA is +46.6 mV, which has a good adsorption performance for MB. In the adsorption process, the effects of adsorption time, pH, and initial MB concentration on the adsorption capacity are studied with the different OSNCs-PA, and the adsorption kinetics and adsorption isothermal curves are also fitted. The results show that the maximum adsorption capacity of OSNCs-0.5%PA, OSNCs-3.0%PA, OSNCs-5.0%PA on MB could reach 142.86, 166.67, and 169.49 mg g−1, respectively. The adsorption of OSNCs-PA for MB conform to the second-order kinetics and the Langmuir adsorption isotherm.