Reclamation of Aged Transformer Oil Employing Combined Adsorbents Techniques Using Response Surface for Transformer Applications

Abstract

The study lowers the environmental risk by combining biodegradable adsorbents with stronger adsorption. This work uses two distinct kinds of adsorbents, namely, polyaniline (PANI)-coated Kappa Cotton (KPC) and activated clay-biopolymer, bentonite (aB) composite, and chitosan (CTN), to recover the aged transformer oil (aTO). Using the Box–Behnken (BB) design paired response surface method (RSM) approach, an experimental sequence was created to determine the optimal ratio of the adsorbent materials. The aTO was supplemented with the homogenized aB-CTN material ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${A}\ast$ </tex-math></inline-formula> ) and PANI-coated-KPC ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${B}\ast$ </tex-math></inline-formula> ) materials. After optimization, it was found that the optimal values for the input variables for the dielectric breakdown voltage and dielectric dissipation factor were <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${A}\ast =1.76$ </tex-math></inline-formula> g, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${B}\ast \,\,=1.28$ </tex-math></inline-formula> g, and temperature <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$= 78.9\,\,^{\circ }\text{C}$ </tex-math></inline-formula> , while stirring duration = 3 h was kept constant. After treatment under ideal conditions, it was found that aTO1 had dielectric characteristics of 46.6 kV and 0.0020 dissipation factor, which are equivalent to those of laboratory studies conducted in triplicate with a 2.5% error. They demonstrate that aTO exhibits an outstanding dielectric response when the optimal proportion of the process variables ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${A}\ast $ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${B}\ast$ </tex-math></inline-formula> ) is used. The removal of impurities from aTO has considerably enhanced its dielectric properties, as seen by the International Commission on Illumination (CIE) chromaticity coordinates, X-ray diffraction (XRD) analysis, ultraviolet (UV) responses, and Fourier transform infrared (FTIR) analyses. The material’s ability to sorb dyes, polar impurities, and heavy metal ions is significantly increased by the expanded active sites of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${A}\ast $ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${B}\ast $ </tex-math></inline-formula> .