The Optimization of Initial Treatment of Seaweed Ulva reticulata Using CEM Synthesizer Method for Bioethanol Production

Abstract

Research has been carried out on the optimization of initial treatment and hydrolysis using CEM microwave synthesizer and the production of bioethanol from Ulva reticulata seaweed. Optimization in the initial treatment was carried out by varying the concentration of HCl and H2SO4 (each in 1; 3; 5; and 7%), variations in time (30; 40; 50; and 60 minutes), temperature (100; 150; 200 and 250 °C), and electrical power (100; 150; 200; and 250 W). Fermentation was carried out anaerobically at 10% inoculum concentration and a production time of 6 days. Characterization of reducing sugar using DNS method and characterization of ethanol using GC-FID and HPLC. The results of the initial lignocellulosic analysis obtained the lignin content of 10.03%, cellulose 14.38% and hemicellulose 22.29%. After the initial treatment, the lignin content decreased to 3.86%, while cellulose increased to 24.50% and hemicellulose to 41.57%. The reducing sugar content produced using HCl is 97.10 g/L at optimum temperature 200 °C, for 60 minutes, using 7% concentration of HCl and 200 W of power, while the optimum reducing sugar content using H2SO4 is 76.40 g/L at optimum temperature 200 °C, time for 50 minutes, using 3% concentration of H2SO4 and 200 W of power. Production of bioethanol through fermentation and distillation processes obtained a bioethanol level of 43.89% (GC) or 18.89% (HPLC) for optimum conditions using H2SO4, whereas for optimum conditions using HCl, the bioethanol level is 44.29% (GC) or 18.09% (HPLC).