Two novel nonylphenoxy acetic acids including (2,6-dimethylheptyl) phenoxy acetic acid (POAA) and (2,6-dimethylheptyl) propanoic acid (POPA) were synthesized via Williamson reaction for the separation of yttrium from rare earth elements (REEs) in this paper. The extraction and stripping of REEs using POAA and POPA have been investigated. The extraction mechanism of REEs could be deduced as ion exchange via mass balance method. There is an outstanding advantage that the separation of heavy REEs (HREEs) with POPA is more efficient than sec-octylphenoxy acetic acid (CA12) and the corresponding separation factors between Y and HREEs such as Er, Tm, Yb, Lu reached 2.00, 2.01, 2.57 and 2.46, respectively. Stripping of loaded POAA and POPA by 1.0 mol/L HCl or more were effectively achieved when the volume ratio of organic phase to aqueous phase is 1:1. A solvent extraction process for separation of high-purity yttrium from ion-absorbed rare earth concentrate using POPA was developed, which are superior to secoctylphenoxy acetic acid (CA12) and naphthenic acid (NA). Yttrium product with a purity of 99.81 wt.% was obtained via 13 stages of extraction section, 10 stages of scrubbing section and 5 stages of stripping section. (C) 2017 Elsevier B.V. All rights reserved.