Dilute Acid Hydrolysis of Cowpea Hulls: A Kinetic Study

Abstract

In this study, dilute acid hydrolysis of cowpea hulls was carried out in two stages under the following conditions: pre-hydrolysis (4%v/v H₂SO₄, 121ËšC, 30 minutes) and hydrolysis ( at 10% and 15% v/v H₂SO₄,varied at different temperatures 150 ^oC, 160 ^oC, 170 ^oC and 180 ^oC for 2.5 hrs.). The substrate was characterized using both Fourier transform infrared spectroscopy and proximate analysis. The percentage lignocellulosic composition of the substrate was obtained for cellulose, hemicellulose and lignin as 34%, 14% and 4.7% respectively. Maximum glucose concentration of 8.09g was obtained using 10%v/v acid concentration at 170ËšC after a reaction time of 90min. Saeman’s model gave a good fit for the experimental data. Activation energy for glucose formation using 10%v/v and 15%v/v H₂SO₄ was obtained as 38.28KJ and 82.204KJ respectively. From the results obtained it can be concluded that cowpea hulls can be converted to a useful product.