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 (A*) and PANI-coated-KPC (B*) materials. After optimization, it was found that the optimal values for the input variables for the dielectric breakdown voltage and dielectric dissipation factor were A* = 1.76 g, B* = 1.28 g, temperature = 78.9 °C, 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 percent error. They demonstrate that aTO exhibits an outstanding dielectric response when the optimal proportion of the process variables (A* and B*) is used. The removal of impurities from aTO has considerably enhanced its dielectric properties, as seen by the CIE chromaticity coordinates, XRD analysis, UV responses, and FTIR analyses. The material’s ability to sorb dyes, polar impurities, and heavy metal ions is significantly increased by the expanded active sites of A* and B*.

Natural Esters (NEs) with a high proportion of Unsaturated Fatty Acids (UFAs) were used in this research. A Superior Insulating Fluid (SIF) is prepared by blending NEs like Baobab Oil (BAO) and Mongongo Oil (MGO) with a pure dielectric like Kerosene (KER) and subjected to ultrasonic wave treatment at 30 kHz. Then, accelerated heating of SIF is carried out in the presence of Kraft Paper (KP) and Copper Plate (CP) for 10 hours a day at 90 °C for 30 successive days. The deterioration of the dielectric characteristics of SIF, KP, and CP was measured as per IEC and ASTM standards before and after the schemes of stressing. The failure rate of SIF, KP and CP was compared to understand the influence of KER in NEs. The KER addition at 5% proportion protects the oil from dielectric weakening, copper from ageing and likewise, the viscosity remains at the original level. The use of KER in NEs have thin the oils and protects the copper from oxidation, thus preserving the quality of oils for several years. The extrapolation of data is done using a polynomial function and for 90 days, where the selected SIFs show 7% of ageing rate when compared to MO that shows 50% ageing rate. This affirms that SIFs are a suitable substitute for Mineral Oil (MO) and reclamation SIFs are achieved using natural reclamation/filtration techniques using Activated Bentonite and Activated Carbon. Hence spilling and reusing the SIFs does not harm the environment as that of Mineral Oil (MO).

In this present work, effort was taken to develop a response surface model based on response surface methodology (RSM) paired with Box–Behnken design (BBD). Investigations were carried out to optimize the transesterification of Pongamia Pinnata oil (PPO) under various process conditions such as time (60–180 min), temperature (60 °C–100 °C), and catalyst (1%–3%). The production of PPO methyl ester (PPOME) by the esterification process is carried out using the PPO and methanol (CH3OH) in a 1:6 molar ratio that is fixed as a constant. Here, the input variables are the process variables (independent) and the output variables are the response variables (dependent). The response variables are the breakdown voltage (BDV), kinematic viscosity (KV), and fire point (FRP). The effect of the process variables on the response variables is modeled using RSM paired BBD. The experimental sequence was designed to find the optimum composition of input parameters and output parameters. The associative effects of the input and output variables were designed as a 2-D contour plot and 3-D response surface plots, and the interactive effects were studied using the plots. After optimization, the optimum conditions of the input variables over the BDV, KV, and FRP were found to be the time of 142.07 min, the temperature of 81.52 °C, and the catalyst of 2.41%. The dielectric properties of PPOME were found to be 61.54 kV, 20.50 cSt, and 281.43 °C, which are in the vicinity of the laboratory experimental results. Those indicate that the treatment of PPO with the optimum quantity of the process variables gives an excellent dielectric response.

This research investigates a tropical indigenous nonedible ester such as Pongamia oil (PO). PO and PO methyl ester (POME) were taken as test samples to develop a nonparametric model for investigations. This work implements the empirical cumulative distribution function (eCDF) to develop a PO and POME lifetime model. The lifetime model of the PO and POME acts as a decisive factor in determining the early failure regions corresponding to the bathtub model. On the other hand, the Bayesian theorem calculates the Bayesian inference. This enables one to foresee the variable as a posterior distribution to conclude their correlation in the parameter space. The developed lifetime model of PO and POME supports experimental results over hypothesis and assists one to predict the risk probability. The model predicted early failures of the PO at less than 40 kV and POME at less than 54 kV and life of POME from 41 to 54 kV and POME at 55–65 kV. The useful life of PO and POME will experience a failure rate of 45% and 25%, respectively. Furthermore, such detections aid power engineers to treat insulating fluids to overcome early aging effects and deterioration of oil–paper insulation.

Increasing usage of petroleum-based insulating oils in electrical apparatus has led to increase in pollution and, at the same time, the oils adversely affect the life of electrical apparatus. This increases the demand of Mineral Oil (MO), which is on the verge of extinction and leads to conducting tests on natural esters. This work discusses dielectric endurance of Marula Oil (MRO), a natural ester modified using Conductive Nano Particle (CNP) to replace petroleum-based dielectric oils for power transformer applications. The Al₂O₃ is a CNP that has a melting point of 2072 °C and a low charge relaxation time that allows time to quench free electrons during electrical discharge. Al₂O₃ is blended with the MRO and Mineral Oil (MO) in different concentrations. The measured dielectric properties are transformed into mathematical equations using the Lagrange interpolation polynomial functions and compared with the predicted values either using Gaussian or Fourier distribution functions. Addition of Al₂O₃ indicates that 0.75 g/L in MRO has an 80% survival rate and 20% hazard rate compared to MO which has 50% survival rate and 50% hazard rate. Considering the measured or interpolated values and the predicted values, they are used to identify the MRO and MO’s optimum concentration produces better results. The test result confirms the enhancement of the breakdown voltage up to 64%, kinematic viscosity is lowered by up to 40% at 110 °C, and flash/fire points of MRO after Al₂O₃ treatment enhanced to 14% and 23%. Hence the endurance of Al₂O₃ in MRO proves to be effective against electrical, physical and thermal stress.