Removal and Recycling of Precious Rare Earth Element from Wastewater Samples Using Imprinted Magnetic Ordered Mesoporous Carbon

Abstract

The present work is devoted toward the development of a highly efficient, low cost, selective and sensitive technique for the detection, removal and recovery of a popular rare earth element, i.e., gadolinium [Gd]. Herein, the magnetic ordered mesoporous carbon (OMMC) is prepared by a green synthesis approach and used as a core for the preparation of imprinted-OMMC using Gd(III) as a template. The prepared material has been used as a coating sorbent for solid phase microextraction (SPME) fiber as well as filled in a small sized micropipette tip to perform the microsolid phase extraction (μ-SPE) based study. The techniques have been explored for different purposes, i.e., preconcentration and trace level detection of Gd(III) has been done by SPME; however, μ-SPE is used for removal as well as recycling of Gd(III) from wastewater samples. The SPME fiber shows a higher preconcentration factor 1400 for Gd(III) with a limit of detection = 2.34 ng L-1, whereas the μ-SPE cartridge shows a higher adsorption capacity (30.2 μg g-1) and removal efficiency (90%) toward Gd(III). Both the techniques have been successfully applied to the preconcentration, detection and removal of Gd(III) from pathological laboratory wastewater, drinking water, sewage sludge, tap water, pond water, river water, human sera, fruits and vegetables and soil and water samples collected from the local coal mines. In addition, the μ-SPE cartridge was successfully applied for recycling of Gd(III) (in solid form) from both pathological laboratory wastewater and coal soil samples.