Manufacture Of Cellulose Nanocrystals From Corncob Hydrolysis Residue

The residue of corncob hydrolysis process as by-product featured as abundance,low cost and renewablilty.The traditional processing method suffered from raw material waste for low efficient utilization and pollution to environment.In this paper,the cellulose purification from corncob,cellulose nanocrystal and microcrystalline cellulose preparation were investigated for valorization of hydrolysis residue of corncob,and microcrystalline cellulose and cellulose nanocrystal were characterized using modern analysis techniques.The main composition of corncob hydrolysis residue was determined with cellulose content of 64.3%,lignin content 26.1%,4.4% ash content,and the others of 5.3%.To investigate the corncob hydrolysis residue of cellulose and lignin in separation and purification process,the optimal process conditions were determined.For improved the utilization of Corncob Hydrolysis Residue?CHR?,separation and purification of cellulose and lignin of CHR the raw material CHR were treated by two stages of alkali H₂O₂ and NaClO₂,in which the percentage content of cellulose and the removal rate of lignin were used as evaluation index,separation and purification of cellulose and lignin were investigated.The results showed that the optimal treatment conditions were that H₂O₂ dosage of 0.8%,NaOH dosage of 3%,extracting temperature of 80?,NaClO₂ concentration of 12g/L,and temperature of 70? at NaClO₂ stage.Under this condition,the percentage content of cellulose was 84.7% and the removal rate of lignin was 91.1% with optimal performance on separation and purification of cellulose and lignin.Preparation of microcrystalline cellulose?MCC?with the purified cellulose as feedstock using dilute acid hydrolysis process was investigated,and effects of acid concentration,temperature and reaction time on properties of MCC were discussed in detail.Then the optimal hydrolysis conditions are temperature at 80?,hydrochloric acid concentration of 8.0% with reaction time of 60 min,by which MCC yield of 50.8% could be achieved.The results of FT-IR and XRD analysis showed that the prepared MCC was cellulose I and its properties could meet the standard requirements.Preparation of cellulose nanocrystal?CNC?with purified cellulose from residual of corncob hydrolysis as feedstock was investigated using ultrasonic-assisted hydrolysis process,and properties of the prepared CNC was analyzed.In addition,the optimal conditions were determined as follows: sulfuric acid concentration of 55%,reaction time of 180 min and temperature of 55 ?,whereby the yield of CNC is 52.2%.The TEM results showed the products are spherical particle with diameter of 25-35 nm and length around 40-55 nm,and the CNC could be well dispersed in water.FTIR results showed the peaks changed little compared to the purified cellulose counterpart,suggesting the chemical structure of cellulose was not destroyed with the original structure retained.The TGA results showed the thermal stability of CNC is slightly lower than that of purified cellulose,however,still higher than that of the starting material.