Synthesis of hyperbranched polymers towards efficient boron reclamation via a hybrid ultrafiltration process

Published Date
Journal of Membrane Science
15 July 2016, Vol.510:112–121, doi:10.1016/j.memsci.2016.03.024

• Author 

• Yu Pan Tang ^a
• Shuman Yuwen ^a
• Tai Shung Chung ^a,,
• Martin Weber ^b
• Claudia Staudt ^c
• Christian Maletzko ^d

• aDepartment of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117585, Singapore
• bAdvanced Materials & Systems Research, BASF SE, GMV/W-B001, 67056 Ludwigshafen, Germany
• cAdvanced Materials & Systems Research, BASF SE, GMM/M-B001, 67056 Ludwigshafen, Germany
• dPerformance Materials, BASF SE, G-PM/PU, 67056 Ludwigshafen, Germany

Received 29 January 2016. Revised 8 March 2016. Accepted 10 March 2016. Available online 12 March 2016. 

Highlights

• •
  A demonstration of hyperbranched polymers as promisingly efficient polychelatogens.
• •
  Two hyperbranched boron-chelating polymers were well-tailored.
• •
  Their chelation capacities were systematically studied in different conditions.
• •
  A boron rejection of 91% was achieved, higher than most of reported data.

Abstract

Two hyperbranched polymers, hyperbranched polyglycidol (HPG) and 2, 3-Dihydroxypropyl-hyperbranched polyethylenimine (Diol-HPEI), were synthesized and studied as polychelatogens for boron reclamation via a hybrid ultrafiltration process, with the objectives of evaluating the key factors for polymer–boron chelation and improving boron rejection efficiency. Their chemical structures were unveiled by FTIR and XPS analyses whilst molecular weights were carefully tailored in order to be fully retained by a commercial ultrafiltration (UF) membrane. The chelation capacity of the two polymers was compared under different operating conditions i.e., chelating temperature, polymer loading and pH. It appears that Diol-HPEI prominently outperforms HPG because the tertiary amine group may be more competent than the ether group in terms of their protonation capability. Eventually, a rejection of 66–91% was achieved with a Diol-HPEI polymer loading of 100 g per g boron in the pH range of 6.9–9.0. Besides, the effects of interfering ions, i.e., Na⁺, Mg²⁺, Cl⁻ and   on polymer–boron interactions were examined in the Diol-HPEI/boron solution at the neutral condition. Results reveal that divalent cations may exert more negative influence on boron rejection owing to the competition between them and boron to form complexes with chelating polymers. These findings may provide useful insights in design of efficient boron-chelating polymers.

Graphical abstract

Keywords

• Chelation
• Boron reclamation
• Hyperbranched polymer
• Ultrafiltration

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• ⁎ 
  Corresponding author.

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