The selective adsorption of anionic dyes over 3D printing composite sorbents of aerogel and porous carbon

As a pollutant widely presented, the dye needs deep purification treatments after use. The traditional ways for dye purification cannot meet the need of selective purification for dyes, especially for the separation between anionic and cationic dyes. In this study, we employ three-dimensional (3D) printing technology to prepare composite sorbents (FGA-PCs) with porous carbon (PC) and foaming gelatin aerogel (FGA). Microscopic analysis indicates that the composite sorbents have well-defined lattice structures. The S_BET value of the representative sorbent is 1019 m² g⁻¹, and the pore-volume is 1.43 cm³ g⁻¹. After adsorption treatment for 60 min, the purification rate of anionic dyes Orange-G (OG) and Methyl-Orange (MO) reach 99 % and 92 %, respectively, with a representative sorbent FGA-PC. In contract, those of cationic dyes Azure-A (TA) and Rhodamine-B (RB) are only 0.55 % and 9.5 %, respectively, showing excellent separation capability for anionic dyes. With the 3D printing, the PC and FGA are combined strongly. According to the experimental and the density functional theory (DFT) results, it can be proved that the electrons of the FGA partially transfer to the PC and the dipole moment of composite sorbents can be changed. Therefore, the composite sorbent FGA-PC displays good adsorption selectivity for anionic dyes.