Response surface methodology optimization study on corncob pretreatment: reduction of sodium hydroxide usage and enhancement in pulpzyme HC biobleaching efficiency

<jats:p>Lignocellulosic rich corncob biomass possesses less complex structure, lignin and
pigment content. As compared to wood pulp, it is considered to be a better alternative for
the production of cellulose fibre. The present study was conducted to optimize both the
alkaline (using sodium hydroxide) and biobleaching (using Pulpzyme HC) pretreatment
process of corncob to promote lignin removal and cellulose swelling. It was the aim of this
work to achieve mild processing conditions for corncob pretreatment in order to minimize
the chemical usage. Results demonstrated that the mild pretreatment approach employed
was found to successfully increase cellulose swelling and lignin removal from the corncob
biomass. In alkaline pretreatment process, reaction temperature showed to be the most
prominent effect in enhancing lignin removal and cellulose swelling as compared to
sodium hydroxide concentration and reaction time. RSM optimized conditions for alkaline
pretreatment process: 0.5 M NaOH, reaction temperature of 80°C and reaction time of 30
mins manage to increase the sedimentation index (indicate swelling of cellulose) from 0 to
30 and reduce the kappa number (represent lignin removal) from 82 to 32, respectively.
Meanwhile, for biobleaching pretreatment using Pulpzyme HC, reaction time play a more
significant role than the Pulpzyme HC concentration in promoting lignin removal and
increasing cellulose swelling. RSM optimized conditions showed that the kappa number
was reduced from 32 to 18 whereas the sedimentation index increased from 30 to 60 when
the alkaline pretreated corncob was biobleached with Pulpzyme HC.</jats:p>