Optimal Synthesis of Aromatic Carbonyl Compounds by Electrooxidation of Soda Lignins on Stainless steel and TiMMO Anodes

Electrooxidation (EO) studies were conducted on Wheat Straw Soda Lignin (WSSL), and bagasse soda lignin (BSL) for the synthesis of aromatic carbonyl compounds (COarom). Stainless Steel (SS), and titanium mixed metal oxide (TiMMO) anodes were used for the purpose. Experiments were designed according to Box Behnken Design (BBD), and Central Composite Design (CCD). The process parameters, namely EO current density, and EO time, were optimized using Response Surface Methodology (RSM) to obtain the maximum yields of different COarom, individually as well as collectively. A maximum of 30% cumulative yield of COarom, based on the total amount of lignin, could be obtained from BSL under optimized conditions of 2.24 mA/cm2 EO current density, and 18 h EO time using SS anode. Among individual compounds, vanillin was produced with the highest yield of 20% of starting BSL with EO current density, and EO time optimized to 5.87 mA/cm2, and 18 h, respectively. In all cases, SS anode fares better than TiMMO anode.