## 3 Results and Discussion
### Techno-Economical Analysis  
In this study, the total capital investment, cost estimation, and profitability of the optimized method were evaluated (Figure 4). The total capital investment, cost estimation, and profitability analysis of the optimized method were thoroughly evaluated. The total capital investment comprised equipment, direct fixed capital, working capital, and start-up costs. Among the cost components, material costs constituted the largest proportion at 97.33%, with the inputs used in this study estimated at USD 400/g for C-PC and USD 0.75/kg for 99% ethanol. Labor costs were the second highest, accounting for 1.50% of the total. Facility-dependent costs, including equipment maintenance, fixed capital cost depreciation, and other related expenses, represented 0.95% of the total costs. Lastly, laboratory, quality control, and quality assurance, and the cost of the optimal method were evaluated (Figure 4). Figure 4: Process flow diagram of PCB production from C-PC using an optimized industrial-scale extraction method. Figure 3: Analytical HPLC chromatograms of standard PCB (PCB STD) and ethanol-extracted PCB (PCB Sample) under optimum extraction conditions. ance (QC/QA) costs accounted for 0.23%. Based on the simulation results, the process allows for 506 batches to be operated annually, with an expected PCB production volume of 147.13 kg/year. The price of the PCB product was set at USD 1,600,000/kg, which was determined by referencing the product price from Santa Cruz Biotechnology, Inc. Therefore, the expected revenue from producing PCB using this process for 1 year is estimated to be USD 235,414,870/year, and the payback time is estimated to be 1.60 years. This model was compared with the well-known PCB methanol extraction method to evaluate its economic viability. In the methanol extraction method, C-PC at a concentration of 1:100 (_w/v_) was extracted using methanol at 60 \({}^{\circ}\)C for 16 h, yielding an efficiency of 27.12%. By operating 317 batches/year, this method produced 84.31 kg/year with a payback time of 7.84 years. The difference in payback time between methanol and ethanol was attributed to the higher yield of ethanol and the absence of toxic waste handling costs. Methanol is listed in the TRI of the US EPA and is known to have significant adverse effects on human health and the environment [33]. Referring to previous studies on methanol disposal costs through incineration (USD 1.05/kg) [19], applying this to our model resulted in an additional annual disposal cost of USD 26,527. The extraction solvent and its optimization are crucial for large-scale extraction processes considering time, cost, and disposal expenses. The financial indicators for ethanol and methanol extraction methods were compared (Table 5). Ethanol and methanol extraction processes show differences in economic performance due to variations in production efficiency, cost structures, and output capacity. Methanol extraction requires a lower initial investment (USD 21,633,680) and operating costs (USD 131,959,686/year), which makes it attractive for projects with budget constraints. However, its profitability is limited, with a gross margin of 2.18%, an ROI of 12.75%, and an IRR of 8.20%. These modest returns are primarily attributed to its lower production efficiency (84.31 kg/year) and higher unit production cost (USD 1,565,095/kg). Furthermore, its longer payback time (7.84 years) and marginal NPV (USD 1,749,872) highlight the process's inability to generate significant value over time. In contrast, ethanol extraction demonstrates higher initial investment (USD 27,867,186) and operating costs (USD 207,987,258/year), but achieves superior profitability due to its greater production efficiency (147.13 kg/year), lower unit production cost (USD 1,413,588/kg), and higher annual revenues (USD 235,414,870/year).