Acid mediated chemical treatment to remove sugar from waste acid stream from nano-crystalline cellulose manufacturing process.

Nano-crystalline cellulose (NCC) is a nano-scale biomaterial derived from highly abundant natural polymer cellulose. It is industrially produced by concentrated acid hydrolysis of cellulosic materials. However, presences of as high as 5–10% of sugar monomers in spent sulphuric acid during the manufacturing process, makes it unsuitable for such recycling or reuse of sulphuric acid. Currently, the industry has been using membrane and ion exchange technology to remove such sugars, however, such technologies cannot achieve the target of 80–90% removal. In the current investigation, thermal treatment and acid mediated thermal treatment have been evaluated for sugar removal from the spent sulphuric acid. Almost complete removal of sugar has been achieved by this approach. Maximum sugar removal efficiency (99.9%) observed during this study was at 120 ± 1 °C for 60 min using 0.8 ratio (sample: acid) or at 100 ± 1 °C for 40 min using 1.5 ratio.