Sustainable reclamation of transformer oils via tailored mesoporous γ-alumina: Oil regeneration and durability performance of adsorbents

The large volumes of waste oils produced by electric power generation systems have heightened concerns about their disposal. As an alternative, the regeneration and reclamation of these oils are environmentally preferred. This study investigates the regeneration of contaminated transformer oil using mesoporous γ-alumina adsorbents synthesized from cost-effective boehmite. Two synthesis routes, thermal–chemical (TC) and chemical–thermal (CT), were evaluated using Taguchi’s L۱۶ orthogonal array to optimize the preparation conditions. The performance of the synthesized adsorbents in oil regeneration was then assessed through a one-step batch adsorption process and multiple saturation cycles. Textural characterization by BET analysis identified the optimal TC-derived γ-alumina with a specific surface area of ۲۲۶.۷۶ m² g⁻¹, a pore volume of ۰.۲۵ cm³ g⁻¹, and an average pore diameter of ۵.۹۵ nm. The optimized adsorbent demonstrated superior physicochemical performance in treated oil, significantly improving the total acid number (TAN), dielectric dissipation factor (DDF), and electrical resistivity. In addition, it exhibited low mechanical erosion (۳.۳۵% within a particle size range of ۰.۷۱۰–۰.۸۵۰ mm), outperforming comparable commercial products (~۷.۰۴% erosion). FTIR and GC–MS analyses confirmed the effective removal of key contaminants, including ۱,۲-benzenedicarboxylic acid derivatives (diisooctyl ester and mono-(۲-ethylhexyl) ester). Based on the latest literature, the comparison of thermal–chemical and chemical–thermal synthesis routes, along with their effects on pore-size distribution and the attrition strength of γ-Al₂O₃ adsorbents, represents a novel aspect of this study and warrants further investigation to maximize adsorption performance.

کلیدواژه ها:

Transformer oil regeneration ، γ-Alumina adsorbents ، Acid leaching ، Surface morphology ، Attrition resistance