Uma Hapani and Linz-Buoy George
Abstract
Lignin is amorphous and branched aromatic heteropolymer, which is mainly comprised of three Phenolic monomers. The heterogeneity of the functional groups and aromatic monomer units in lignin makes it more resource-efficient for preparation of bio-based and high-value chemicals. In the present study, lignin separation from four-agriculture waste was carried out using the modified eco-friendly soda-lignin process, which is sulfur-free and low-cost compared to other methods. The reaction parameters such as concentration of NaOH (%), time (hr), and temperature examined to evaluate the optimum reaction conditions. The optimum reaction conditions were the maximum lignin yields from (Fenugreek (15.54%), Chickpea (18.09%), Fennel (16.22%), and Cumin (15.86%) stems were recovered at 12% NaOH, 105 oC temperature for 3hr. To check the purity of the separated ligninâs were characterized by FTIR and XRD analytical techniques. FTIR studies examined the presence of various functional groups in the separated lignin. Further, it confirmed by comparison with commercial kraft lignin. FTIR studies revealed that separated ligninâs contain principal structural units of the ligninâs. X-ray diffractograms used for the determination of the nature of separated ligninâs. The X-ray diffractograms of the separated lignin showed a similar pattern to the kraft lignin. It indicated that performed alkaline treatment to separate lignin from the samples dissolve ligninâs effectively. To check its potential as an antioxidant, 2, 2-Diphenyl-1-picrylhyrazyl (DPPH) antioxidant test performed. In conclusion, lignin separated from agricultural waste using the soda-lignin process showed good antioxidant efficiency, so it can be used in future applications in the cosmetics and pharmaceutical industries.