Utilization of Modified Attapulgite for the Removal of Sr(II), Co(II), and Ni(II) Ions from Multicomponent System,...

Radionuclide sorption by natural and modified clays is extensively accepted to be an important process from the radioactive waste point of view. This work focused on modification of natural attapulgite with a layered double hydroxide to produce a novel chemisorbent for Sr²⁺, Ni²⁺, and Co²⁺ removal from multicomponent solution. The structural and surface characteristics of both attapulgite (ATP) and modified attapulgite (LDH-ATP) were investigated using XRD, FTIR, SEM, and thermal analysis. Comparison of sorption features of Sr²⁺, Ni²⁺, and Co²⁺ onto ATP and LDH-ATP was achieved; the results indicated that LDH-ATP was the most efficient sorbent for Sr²⁺, Ni²⁺, and Co²⁺. Kinetic studies established that the sorption is fast and reaching >90% within 30 min. The sorption of Sr²⁺, Ni²⁺, and Co²⁺ are well defined by non-linear pseudo-second-order model and controlled by an intra-particle diffusion mechanism. The diffusivity was determined using homogeneous surface diffusion (HSDM) model and found in the order 10^-13 m²/min; this confirmed that the sorption of the three ions is chemisorption process. LDH-ATP can be employed as a candidate chemisorbent for the removal of some metal ions from waste solution.