**Abstract**

Bagasse is scientifically defined as waste from the extraction of sugarcane liquid after the grinding process. Bagasse is biomass which is used as raw material to be processed into surfactants. Bagasse fiber cannot be dissolved in water because it consists mostly of cellulose, pentosane and lignin. The optimum conditions for obtaining the highest yield and the best conversion of bagasse to lignin were achieved when used 80 mesh bagasse and 3 M NaOH as a hydrolysis agent. Then lignin is reacted with 0.25 sodium bisulfite to the surfactant sodium lignosulfonate. Lignin and sodium lignosulfonate were further characterized using a FTIR spectrophotometer to determine the components contained therein. The lignin component consists of phenolic functional group elements, aliphatic and aromatic groups, ketone groups, aren functional groups, amine groups and alkyl groups along with standard lignin components. Likewise with lignosulfonates, with indicator components consisting of C═C alkenes, Sulfate S═O, C═O carboxylic acids and S-OR esters. The NMR test was resulted the monomer structure of SLS surfactant bagasse. The results indicate that the lignin isolation process from bagasse has been successfully. Likewise, the sulfonation of lignin to lignosulfonate is also successful.

**Keywords:** bagasse, FTIR, isolation, lignin, lignosulfonate, sulfonation
