Selective recovery of rare earth metals from acid mine drainage by pyrrolidine diglycolamide silica column

We developed an adsorption column that can be used for rare earth recovery from acid mine drainage (AMD). 2[2-oxo-2-(1-pyrrolidinyl)ethoxy] acetic acid was used as a functional ligand grafted onto amino silica gel, resulting in an adsorbent selective for rare earth metals. Adsorption columns for the enrichment of rare earth metals have been made using this functional silica. A flow rate of 500 & mu;L min-1 and an eluent of pH= 2 0.013 mol L-1 DTPA were determined as the optimum operating conditions. The recovery of actual AMD using SiO2 @PYRDGA adsorption column achieved 82.29%, 75.66%, 85.10%, 78.43% for Er, Gd, Nd and La, and the purity of rare earth in AMD can be increased about 10 times after recovery. In addition, the thermodynamics, kinetics, adsorption mechanism, and theoretical calculations of the adsorption process were investigated in detail.