Application of Response Surface Methodology in Optimizing Thiourea Leaching for Metal Extraction from E-Waste
Norul Fatiha Mohamed NOAH, Norasikin OTHMAN, Izzat Naim Shamsul KAHAR, Sazmin Sufi SULIMAN, Shuhada Atika IDRUS-SAIDI, Aishah ROSLI
Abstract. Electronic waste (e-waste) is an escalating environmental concern that poses significant risks to human health and ecosystems. Despite its hazardous nature, e-waste is rich in valuable metals, particularly gold (Au), which has a high economic value and is experiencing a rising market price trend. Consequently, Au recovery from e-waste is crucial for long-term environmental sustainability as well as economic feasibility. This work describes a less harmful thiourea leachate method for removing gold from used printed circuit boards (PCBs). The study looks at a number of variables, such as the concentration of thiourea, the concentration of acid, and oxidizing agents, that affect how effective the leaching process is. To improve Au recovery, Box-Behnken design and Response Surface Methodology (RSM) are used to optimize these parameters. The maximum predicted Au extraction performance was found to be 2.81ppm, achieved at specific conditions of 57.971 mL H₂O₂, 0.502M thiourea, and 1.006M H₂SO₄. The observed extraction value closely matched this prediction at 2.87ppm, indicating a deviation of less than 5%. The results highlight thiourea as the most significant variable influencing Au recovery, with the interaction between thiourea and H₂SO₄ playing a critical role in the leaching process. Also, the separation factors (β) indicate that Au can be efficiently separated from other metals, particularly copper and aluminium, with high separation factors of 31.10 and 18.59, respectively.
Keywords
Leaching, Gold Recovery, Thiourea Leachate, Waste Printed Circuit Boards, Electronic Waste, Box-Behnken Design
Published online 1/15/2026, 9 pages
Copyright © 2026 by the author(s)
Published under license by Materials Research Forum LLC., Millersville PA, USA
Citation: Norul Fatiha Mohamed NOAH, Norasikin OTHMAN, Izzat Naim Shamsul KAHAR, Sazmin Sufi SULIMAN, Shuhada Atika IDRUS-SAIDI, Aishah ROSLI, Application of Response Surface Methodology in Optimizing Thiourea Leaching for Metal Extraction from E-Waste, Materials Research Proceedings, Vol. 59, pp 1-9, 2026
DOI: https://doi.org/10.21741/9781644903957-1
The article was published as article 1 of the book Separation Technology
Content from this work may be used under the terms of the Creative Commons Attribution 3.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
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