Efficient removal of Sr(II) from aqueous solution by melamine-trimesic acid modified attapulgite composite

Melamine (MA)-trimesic acid (TMA) modified attapulgite (ATP–TMA–MA) with high adsorption capability for Sr(II) was successfully synthesized using attapulgite (ATP) as a matrix via a facile two-step approach. Batch adsorption experiments indicated that the adsorption kinetics followed the pseudo-second-order equation and isothermal adsorption data fitted well with the Freundlich isotherm model. The adsorption thermodynamic analysis indicated that Sr(II) adsorption onto ATP–TMA–MA was a spontaneous and endothermic process. Sr(II) adsorption mechanism of ATP–TMA–MA was mainly decided by chemisorption. TMA–MA molecules grafted on ATP surface markedly improve the removal efficiency of ATP–TMA–MA for Sr(II).