Adsorption performance of activated bentonite, zeolite 13X and activated carbon for aminophenazone in transformer oil

Abstract Aminophenazone (AP) is one kind of harmful additives in transformer oil. It results in a significant drop of the insulation property of transformer oil and thus leads to substation accidents. Adsorption method has proved to be an efficient approach for AP removal. In this work, activated bentonite, zeolite 13X, and activated carbon were chosen as adsorbents for the separation of AP from the polluted transformer oil. At 25 ℃ and initial AP content is 400 ppmw, the AP uptake of activated bentonite (151.2 mg/g) is much higher than that of zeolite 13X (52.1 mg/g) and activated carbon (45.0 mg/g). The desorption activation energy (Ed) of AP on the three adsorbents follow in the order: activated bentonite (115.73 kJ/mol) > activated carbon (52.51 kJ/mol) > zeolite 13X (51.23 kJ/mol). Activated bentonite exhibits the highest AP uptake due to the existence of acidic sites that can strongly interact with alkaline AP and the pore sizes that facilitate AP molecules to more easily enter into the adsorbent channels. Activated bentonite is an industrially promising adsorbent for the removal of AP from the polluted transformer oil.