Thermoseparative Regeneration of Triblock Copolymer after Aqueous Biphasic Extraction of Molybdate Species Laboni Das, † Sankar Prasad Paik, ‡ and Kamalika Sen* ,† † Department of Chemistry, University of Calcutta, 92 APC Road, Kolkata 700 009, India ‡ Department of Chemistry, Sundarban Mahavidyalaya, Kakdwip 743347, India * S Supporting Information ABSTRACT: The present study aims at the generation of a triblock copolymer vs sodium sulfate aqueous biphasic system (ABS), its application toward extraction of molybdenum species, and finally purification and regeneration of the block copolymer. The ABS was characterized for its biphasic region by constructing the phase diagram using turbidometric titration methods. Extractions were monitored using the spectrophotometric method directly in the block copolymer medium. Complete extraction of molybdenum species was observed in this method. Interference from other closely related metal ions in the extraction process was found to be negligible excepting oxo and polyoxometallates of vanadium and tungsten. Regeneration of the polymer was done using a thermoseparation technique followed by successive treatment with ion exchange resins. ∼87% of the pure triblock copolymer could be regenerated as a result of such treatment. 1. INTRODUCTION An aqueous biphasic extraction system is a complete aqueous substitute of the traditional liquid-liquid extraction technique which involves organic solvents having high volatility and toxicity. 1 Aqueous biphasic systems (ABSs) deal with water as the solvent, which supports a greener future for the separation technology. ABSs also frequently deal with the use of biocompatible reagents. 2 In general, mutually incompatible aqueous polymer-polymer or polymer-salt or polymer- surfactant or salt-salt solutions are mixed at certain thermodynamic conditions (like pH, temperature, concen- tration etc.), to generate an ABS. 3,4 Although a large number of ABSs composed of an individual unit of the block copolymers like polyethylene glycol (PEG) are reported in the literature, only a few are available involving triblock copolymers. Some of them are composed of poly(ethylene glycol)-block-poly(propylene glycol)-block-poly- (ethylene glycol) (PEG-PPG-PEG) vs various sulfate salts (Li 2 SO 4 , MgSO 4 , Na 2 SO 4 , and ZnSO 4 ). 5 Some others are also composed of poly(propylene glycol)-block-poly(ethylene gly- col)-block-poly(propylene glycol) (PPG-PEG-PPG) vs sodium tartrate, 6 sodium acetate, or sodium citrate. 7 Design of a new ABS demands its complete characterization in terms of phase diagrams which are conveniently achieved through a cloud point determination technique or turbidometric method or node determination method. Tie lines representing the final compositions of the top and the bottom phases help to have an actual idea about the ABS. 8 Received: June 2, 2018 Accepted: December 14, 2018 Figure 1. Binodal curve of ABS composed of PPG-PEG-PPG/ Na 2 SO 4 at: black square, 293 K; red circle, 298 K; and blue triangle, 310 K. Article pubs.acs.org/jced Cite This: J. Chem. Eng. Data XXXX, XXX, XXX-XXX © XXXX American Chemical Society A DOI: 10.1021/acs.jced.8b00455 J. Chem. Eng. Data XXXX, XXX, XXX-XXX Downloaded via UNIV OF BRITISH COLUMBIA on January 1, 2019 at 22:51:44 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.