Rice husk is a byproduct of the milling process of paddy into rice. Lignin can
be obtained from rice husk to be utilized in various fields in the industry into high
value products. Lignin is a complex polimer with high molecular weight which
compiled of fenilpropane units. This study aims to determine the influence of
variable temperature isolation, time isolation, and the concentration of NaOH
during the isolation of lignin from rice husk by ultrasonic heating and also to know
the characteristics of lignin using FTIR. The variables used are the temperature of
the isolation on the 50oC and 70oC, the time of isolation is 30 and 60 minutes, and
the concentration of NaOH at 5% and 10%. The factors that most affect the
acquisition of % yield of lignin of rice husk is the concentration of NaOH, the value
of the effect is 2.7719 and P=0.007, while the next factor is the temperature of the
isolation with the value of the effect is 1.9481 and P = 0.034 , and the next is a time
of isolation that the value effect is 0.8706 and P = 0.287. Based on the FTIR test
that comparing the lignin commercial with lignin the results of the experiment, it
can be seen that the product resulting from the experiment is lignin it is seen from
the wavelength which is almost the same between the lignin commercial lignin
research results.