Synthesis and absorption property of hybridized zinc silicate adsorbent based on natural Illite/Smectite clay

Hybridized zinc silicate adsorbent (Zn–Si/(I/S)) with excellent adsorption property was synthesized by hydrothermal-roasting process based on Illite/Smectite (I/S) clay. The morphological structures and elemental compositions of adsorbents were analyzed by various characterization techniques, and the Zn–Si/(I/S) adsorbent had a 2-D film-like structure. In addition, the average pore size was obviously increased. The Zn–Si/(I/S) adsorbent had a good adsorption performance for cationic dyes and antibiotics, and the adsorption process was influenced by the structure, pore size, type and surface groups of the pollutants. The results of adsorption isotherm, kinetic and thermodynamic model fitting showed that: i) the adsorption performance depended on the pore size and surface charge rather than the specific surface area, ii) the proposed second-order kinetic model and Freundlich isotherm model fitted the adsorption process of RhB better, iii) the thermodynamic analysis proved that the adsorption process proceeded spontaneously by heat absorption. In summary, the adsorption mechanism was controlled by electrostatic attraction, chemical conjugation, ion exchange, hydrogen bonding interactions and pore adsorption.