Synthesis, characterization and evaluation of novel HIPE hydrogels: Application for treatment of hazardous waste incineration plant effluent

Abstract

Novel high internal phase emulsion (HIPE) hydrogels were prepared by oil-in-water emulsion copolymerization of 2-hydroxyethyl methacrylate (HEMA) and N-isopropylacrylamide (NIPAm) in the presence of N,N′-methylene-bis-acrylamide (MBAm) as a crosslinker. Poly(ethylene oxide) based macroinimer was also used as an additional co-surfactant and co-crosslinker. The amount of NIPAm and macroinimer was varied to optimize composition of the hydrogels which sequentially enhanced swelling and metal ion binding capabilities. Swelling properties of all HIPE hydrogels were investigated at different temperatures with a maximum swelling percentage value of ∼2100% determined at 25 °C. Young’s modulus (E) of HIPE hydrogels which is a critical property for understanding their mechanical bevaiors was also calculated and the value increased from 5 to 13 MPa by increasing macroinimer amount. Finally, the use of the prepared HIPE hydrogels in a process to identify the best fitting hydrogel composition was applied as binding materials for the recovery of heavy metals ions such as Pb²⁺, Cu²⁺ and Hg²⁺ from hazardous waste incineration plant effluent. Results deduced a decrease in heavy metal ion binding capacity with increasing temperature in the studied range from 25 °C to 40 °C. Furthermore, heavy metal ion removal based on Venturi scrubber and physicochemical (P/C) plant effluent as wastewater was determined and the maximum binding capacities of the hydrogels were in the magnitude of Cu²⁺≅ Hg²⁺ > Pb²⁺ and Cu²⁺ > Pb²⁺ > Hg²⁺ for Venturi scrubber and P/C plant effluent, respectively.

GRAPHICAL ABSTRACT

Keywords:

• Heavy metal ions
• HIPE
• hydrogel
• macroinimer
• N-isopropylacrylamide

Acknowledgements

The authors would like to thank İZAYDAŞ for supplying wastewater and measuring metal ion concentrations by ICP-MS.

Authors’ contributions

Conceptualization, methodology, formal analysis and data curation was performed by Ömer Ferkan Kemik. Conceptualization, data analysis, writing-original draft, editing and supervision was done by Ufuk Yildiz.

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.