Production of formic acid from oil palm empty fruit bunch via dilute acid hydrolysis by response surface methodology

Abstract

Formic acid is the simplest carboxylic acid which has myriad applications in food, textiles, agriculture, pharmaceutics, and chemicals. Formic acid can be synthesized from hydrolysis of lignocellulosic biomass. Oil palm empty fruit bunch (OPEFB) is lignocellulosic biomass produced by oil palm industries to which cellulose content has potential for conversion into formic acid by hydrolysis. We investigated effects of three parameters in acid-catalysed hydrolysis reaction of OPEFB such as reaction time (20, 40, 60 minutes), temperature (140, 160, 180 °C), and H₂SO₄ concentration (0.3; 0.5; 0.7 M) and optimized them to obtain maximum formic acid concentration by using response surface methodology. Microwave assisted alkaline pretreatment of OPEFB sample under microwave radiation at 840 Watt for 9 minutes with 2% NaOH concentration was done prior to hydrolysis. The pretreatment was effective to reduce lignin content of OPEFB from 28.9% to 7.6%. The highest actual formic acid concentration we obtained from the experiment was 2725 ppm at 180 °C, 60 minutes reaction time, and 0.5 M H₂SO₄. While according to the polynomial model, the optimal condition for obtaining maximum formic acid concentration of 2890.673 ppm was at 180 °C, reaction time of 60 minutes, and 0.3 M H₂SO₄.