Removal of chlorophyll and tannins from Anthocleista schweinfurthii Gilg leaves by electrocoagulation using iron electrodes: optimization using response surface methodology

BACKGROUND An electrocoagulation process using iron electrodes was applied for chlorophyll and tannins removal from ethanol extract of aerial parts of Anthocleista schweinfurthii Gilg. A second-order regression using Central Composite Design (CCD) was used to investigate the main effects of four independent variables, namely supporting electrolyte concentration (in g L-1), ethanol percentage (%), current intensity (in amps) and electrolysis time (in minutes) and their interactions. The chlorophyll removal (CR), total tannins content (TTC) and total phenols content (TPC) were analyzed using response surface methodology (RSM) and CCD. Crude and optimized extracts were characterized by UV-visible spectrometry and Fourier-transform infrared spectroscopy. RESULTS The RSM model obtained from the present study (R-2 > 0.95) showed a good fit which suggests a good correlation between the predicted values and experimental results of CR and tannins removal. Under optimized conditions (supporting electrolyte concentration 2.4 g L-1; ethanol percentage 67%; current intensity 0.4 A and electrolysis time 75 min), CR of 98.23% and TTC of 58.83% were achieved while remaining 91.21% of TPC. CONCLUSION Ethanol percentage, current intensity and electrolysis time influences positively CR, TTC and TPC. According to the results, electrocoagulation is an appropriate technique indicated for extracting secondary metabolites while reducing the risks associated with the use of organic solvents. (c) 2020 Society of Chemical Industry