Selective micro extraction of rare earth elements and yittrium in rock samples using silica modified with xylenol orange and their determination by ICP-AES

Abstract

A systematic study on the selective extraction of rare earth elements (REEs) and yttrium onto silica modified with xylenol orange (SMXO) was carried out and a scheme for the pre-concentration and separation of REEs and Y in rock samples is discussed. A simple single step preparation of silica and its modification by xylenol orange in presence of cetyltri-methylammonium bromide is enumerated. Characterisation of prepared adsorbent was carried out by surface area analysis, IR data and SEM data. REEs and Y were adsorbed onto SMXO at pH ≥ 3 and after a contact period of 30 minutes. Adsorbed REEs and Y were eluted from SMXO with 0.5% (w/v) EDTA solution. Aluminium and iron when present above 200 mg/L were interfering in the analysis of REEs. Aluminium interference was eliminated by removing it as sodium aluminate in the fusion stage of rock samples. Interference of Fe3+was avoided by reducing Fe (III) to Fe (II) using hydroxylamine hydrochloride. Separated REEs were determined by ICP-AES. The proposed method is simple, accurate and the precision is characterized by the % RSD ranges from 2.0-5.1% at the determination limit ranging from 0.2-5µg/mL.