Constructing a novel three-dimensional multi-stage pore structure to facilitate heavy metal adsorption on ceramsite

A novel faujasite (FAU) type zeolitized ceramsite (FZC) was prepared via a novel three dimensional (3D) in-pore growth method. FZC is a centimeter sized spherical particle with a 3-dimensional radial morphology inside, with a specific surface area and pore volume 6 and 30 times that of the original ceramsite, respectively. The unique structure was constructed through electrostatic and polymerization interactions between hexadecyl trimethyl ammonium bromide (CTAB) micelles, ceramic pore walls and silicate aluminate ions, which could simultaneously improve adsorption capacity and mass transfer, endowing FZC with excellent heavy metal adsorption properties. FZC-50 could remove the majority of Cu and Zn from solution within shorter periods (73.3 % and 80.0 % of original ceramsite, respectively) with larger adsorption capacities (340 % and 370 % of original ceramsite, respectively). Theoretical analysis and regeneration experiments both indicate that the adsorption of Cu(II) and Zn(II) on FZC-50 is dominated by ion exchange. And the spent sorbent can be effectively regenerated by NaCl, and the cycle number is expected to be 33 and 26 times for Cu(II) and Zn(II) adsorption, respectively. This work proposed a novel synthesis route to construct a 3D multi-stage porous zeolite inside ceramsite, and opened up new ideas for the further development of zeolitized ceramsite.