Alkaline ball-milled peanut-hull biosorbent effectively removes aqueous organic dyes

Advanced biosorbents increasingly attract attention for their application in environment remediation. Here, a facile one-step approach to alkaline ball milling was used to synthesize a porous peanut hull biosorbent without heating. The alkaline ball-milled peanut-hull (ABP) biosorbent was characterized for its ability to remove Congo red (CR), titan yellow (TY), and methyl violet (MV) from aqueous solutions. ABP processed abundant O-containing functional groups and developed porosity, resulting in maximum sorption capacities of 4864.4 (CR), 455.9 (TY), and 126.1 (MV) mg g^-1. Freundlich isotherm and PSO kinetic models best fit the anionic dye's (CR and TY) adsorption by ABP, indicating multiple mechanisms might control the adsorption process. Freundlich and PFO kinetics models best described cationic MV adsorption by ABP, suggesting the adsorption of cationic dye could also be governed by multi-mechanisms but less heterogeneous than that of anionic dye. The results suggest that alkaline ball-milling is promising approach to converting biomass into advanced biosorbents for organic dyes, especially anionic ones.