Vol. 29 No. 3 (2026) Cover Image
Vol. 29 No. 3 (2026)

Published: September 20, 2026

Pages: 450-465

Articles

Performance of Metakaolin-Reinforced Unsaturated Polyester Resin in Metal Recovery from Wastewater and Potential of Wear Resistance

Raghad Hamid Hilal 1 Wafaa K. Khalef 1 Rafah Alwan Nassif 1
1 College of Applied Sciences, University of Technology, Baghdad- Iraq
History
  • Received: October 8, 2025
  • Revised: November 11, 2025
  • Accepted: December 13, 2025
  • Available Online: September 20, 2026
DOI

https://doi.org/10.29194/NJES.29030460

Abstract

Polymer composites reinforced with clay have garnered substantial academic and industrial interest owing to their environmental and mechanical benefits. This research focuses on the effectiveness of metakaolin-unsaturated polyester composites for sequestering Ni2+ ions from Ni(NO3)2 aqueous solutions and on their tribological performance. The composite materials were synthesized with varying metakaolin concentrations (1, 1.5, 3, and 5 wt.%) to evaluate the influence of clay content on nickel ion recovery and wear resistance. The experimental results show a direct correlation between the reinforcement percentage and the functional properties of the composites. The highest value (61.415%) of Ni+2 recovery efficiency was achieved at a metakaolin concentration of 5 wt.%, which is due to the increased density of active adsorption sites on the composite surface. Conversely, composites with lower metakaolin content exhibited diminished recovery rates due to a limited number of available sites for ion adsorption. Wear resistance results show the same trend, wherein the composite with 5 wt.% metakaolin exhibited maximum wear resistance, characterized by minimal material loss at the applied loads (5, 10, 15, and 20 N). Furthermore, Shore-D hardness measurements indicated a gradual enhancement in the material's hardness with increasing metakaolin content, which confirms the reinforcing role of the clay in enhancing the mechanical properties. Scanning Electron Microscopy (SEM) micrographs showed the formation of wear grooves aligned with the sliding direction during wear testing. In addition, agglomerates and surface deposits were formed that are correlated with the adsorption of metal ions onto the composite surface. These results prove that the incorporation of metakaolin as a reinforcing agent confers dual advantages: it significantly enhances the adsorptive capacity for Ni+2 ion recovery and improves the tribological and mechanical properties of the composite. This positions the material for use in environmental remediation, especially wastewater treatment, and in engineering applications requiring enhanced durability.

Keywords

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