Extraction of bioactive components from hibiscus sabdarifa and investigation of its effect in dye-sensitized solar cells

In this study, plant extracts were obtained by subjecting Hibiscus sabdariffa leaves to soxhlet extraction, maceration technique and ultrasound-assisted extraction. All experiments were modeled using the Response Surface Method (RSM). As an independent variable for Soxhlet extraction, alcohol/water ratio (v/v), the amount of solid (g) and extraction time (min) were selected. The independent variables for maceration technique and ultrasound-assisted extraction were alcohol/water ratio (v/v), temperature (°C), the amount of solid (g) and extraction time (min). Total phenolic content (TPC), total flavonoid content (TFC), FRAP, ABTS and DPPH were selected as response variables. As a result of analysis of variance (ANOVA), high regression coefficients were obtained for the response variables. The highest value for TPC was obtained as 420.4 mg GA/g KM in ultrasound-assisted extraction at 50% alcohol/water concentration, 80 °C temperature, 1.5 g solid, 180 min. The highest value for the total flavonoid content was obtained as 81.72 mg QE/g KM at 50% alcohol/water concentration, 50 °C temperature, 1.5 g solid, 180 min. The highest value for FRAP was obtained as 158.23 mg Trx/g KM at 50% alcohol/water concentration, 80 °C temperature, 0.5 g solid, 180 min. The highest value for ABTS activity was obtained as 78.4% at 60% alcohol/water concentration, 3.5 g solid, 105 min. The highest value for DPPH inhibition was obtained as 86.04% at 50% alcohol/water concentration, 50 °C temperature, 1.5 g solid, 180 min time. DSSC, a natural dye derived from Hibiscus Sabdariffa, was also used. The photovoltaic data of DSSC were found to be Jsc=1.23 mA/cm2, Voc=0.350 V, FF=0.496 and ɳ= 0.028%. According to these results, Hibiscus sabdariffa dye provided a very good efficacy on DSSC.