A novel adsorbent drived from salted egg white for efficient removal of cationic organic dyes from wastewater

[Display omitted] •Salted egg white (SDEW), as a waste natural protein, is chosen to construct a adsorbent.•A new type of adsorbent with nanoscale porous structure.•Dried desalinated SDEW hydrogel shows a good separation performance.•Dried desalinated SDEW hydrogel can remove methylene blue (MB). Desalted duck egg white adsorbent (DSA) was prepared from salted duck egg white (SDEW), enabling high-value recycling of food industry by-products. The purpose of this research was to prepare SDEW hydrogel by microwave hydrothermal method, and then develop a desalted SDEW adsorbent by freeze–thaw and solvent exchange treatments. These treatments have the potential to enhance the adsorption performance of DSA. Methylene blue (MB), as an organic toxic dye, was selected as a representative to study the adsorption capacity of DSA. DSA can effectively remove MB from wastewater with an adsorption capacity of 166.67 mg·g-1, and the binding of MB to DSA was mainly due to hydrogen bonding and electrostatic attraction. Reusability test showed that MB removal efficiency remained above 83.26 % after 10 cycles of adsorption–desorption. This study provides an economical and highly effective solution to reuse and recycle food by-product SDEW.