New optimization approach for amphoteric/magnetic ramie biosorbent in dyestuff adsorption

Abstract

There is growing interest for the utilization of biomass for environmentally friendly adsorbents, and optimizing the complicated and multi-functional structure of biosorbents remains challenging. Herein, ramie waste biomass-based adsorbents with amphoteric/magnetic multi-structures via two different fabrication routes were constructed, studied and optimized to fill the gaps between multi-structure of biosorbent and performance requirements. The results show that the biosorbents exhibit excellent adsorption and magnetic recovery performance, while the biosorbent with amphiprotic-magnetic structure exhibits higher adsorption capacities for methylene blue and congo red with maximum 195.9 mg/g and 147.7 mg/g. These results are attributed to optimization of multi-structure by regulating the introduction strategy of amphiprotic groups and Fe3O4 magnetic nanoparticles. The adsorption processes of the biosorbents accord well with the pseudo-second-order kinetic model and Langmuir isotherm model, which suggests dyestuff are adsorbed via a monolayer spontaneous chemical reaction, and hydrogen bonding and electrostatic interaction are the dominant adsorption mechanisms. These demonstrate that the optimized preparation of the biosorbent improves the adsorption capacity, reusability, and stability, and provides a new perspective for the preparation of high-efficient biosorbents with multi-structures and the purification of dye-polluted wastewater.