Extraction of shikimic acid and recovery of lignocelluloses from water hyacinth

Shikimic acid (SA) is a valuable compound found in water hyacinth. Also, water hyacinth is a rich source of lignocellulosic material. In the present study, conventional extraction was employed for recovering SA from the stem of the weed by varying parameters such as stirring time, solvent volume, temperature and solvent composition. The highest yield of SA (2.48%) was obtained using 20 mL water at 30 °C for 40 min. For extraction of lignin and cellulose from the residual water hyacinth, an organosolv (using 80% ethanol) and alkali treatment have been used to isolate lignin and cellulose, respectively. The lignin content has been found to be 16% in the stem of water hyacinth whereas in pulp from organosolv process it was 9% when treated with sulphuric acid. The highest yield of lignin (7%) and cellulose (31%) were obtained at 210 °C and 36 bar while employing organosolv process. Alkali treatment of water hyacinth stem with 8% NaOH was carried out in an autoclave at 120 °C and 160 °C, and 21.87% of lignin was recovered at 160 °C and 5 bar. Characterization of lignin and cellulose using FT-IR and TGA has confirmed their resemblance with data reported in the literature. Thus, the present study was aimed to utilize the water hyacinth with minimum waste generation and thereby achieving the sustainable solution. Graphical abstract