Speakers - 2026

Title: Optimization of the synthesis of a geopolymer based on volcanic slag and iron filings for the decolorization of used palm kernel oil employed in electrical transformers

Abstract

The management of used palm kernel oils employed as lubricants in transformers represents a major environmental and economic challenge due to their high content of oxidized compounds, colored pigments, and trace metals. In this study, an acid iron-doped geopolymer (GPa/Fe) was synthesized from Manjo volcanic slag and iron filings, and optimized using a three-factor Box–Behnken design (slag mass 3–5 g, iron 0–10 %, H3PO4 30–70 %) with the methylene blue index (MBI) as the response. ANOVA validated the quadratic model (p < 0.05, R2 = 0.98), and the optimal conditions (3.88 g slag, 9.07 % Fe, 30 % H3PO4) led to a maximum MBI of 37.97 mg·g-1. Physicochemical characterizations (optical microscopy, TGA, IR) revealed a homogeneous matrix, thermally stable up to 700 °C, rich in Si–O–Al and Fe–O sites favorable for adsorption. In batch tests, oil decolorization reached 82 % using 2 g of adsorbent for 30 mL of oil. Adsorption isotherms were best fitted by the Langmuir model (R2 = 0.85), indicating well-defined monolayer adsorption. Kinetic studies showed that the decolorization predominantly follows a pseudo-first-order model, suggesting that the process is mainly controlled by the rate of site occupation and physical interactions between the oil and GPa/Fe. These results confirm that GPa/Fe is a promising, eco-friendly, and cost-effective adsorbent for the regeneration of used palm kernel oils and open perspectives for local valorization of volcanic and metallic wastes.

The audience take away from presentation:

• Understanding of Box–Behnken optimization for geopolymer synthesis.
• Insights into the valorization of volcanic and metallic wastes in environmental remediation.
• Practical methodology for decolorization and regeneration of industrial oils.
• Demonstration of low-cost, sustainable adsorbent production.
• Applicability of geopolymer-based materials to broader waste management challenges.