Selective removal of lanthanum from monazite – (Nd) ores by pH-controlled mixed micelle cloud point extraction

Abstract

A novel extraction method via cloud point extraction was used for the pH- selective separation of lanthanum ions from a number of real samples. The formation of a binary complex between La(III) with cetyltrimethyl ammonium bromide (CTAB) and Eriochrome cyanine R (ECR) is the main idea for the proposed study. The obtained complex could be extracted easily by Triton X-114 at 45 °C. The amount of La(III) was determined before and after separation process using an ICP-OES. The primary factors controlling the extraction of La3+ were extensively examined. To cause the clouding phenomenon and, achieve high extraction efficiency, KNO3 and CTAB must be present. The extraction efficiency was greater than 95% under ideal conditions for the concentrations strating from 0.09 to 60 µg mL−1 and a low detection limit (0.3 μg L- 1) with a preconcentration factor of 100. Moreover, by simply changing the pH of the aqueous phase, La(III) can be extracted with high selectivity from a variety of complicated matrices. The findings showed that at pH 3.5, La3+ completely extracted in the micellar phase but Nd(III) does not separate at all. These results demonstrate the reliability of the new method for selective separation of La(III).