摘要
Cellulose nanocrystals(CNCs)have garnered increased attention due to their renewable nature,abundant feedstock availbility,and good mechanical properties.However,one of the bottlenecks for its commercial production is the drying process.Because of the low CNC concentrations in suspension after isolation,CNC drying requires the removal of a large amount of water to obtain dry products for the following utilization and saving shipping costs.A novel multi-frequency,multimode,modulated ultrasonic drying technology was developed for CNC drying to improve product quality,reduce energy consumption,and increase production rate.CNCs dried with dif-ferent drying technologies were characterized by Fourier transform infrared(FT-IR)spectra anal-ysis,X-ray diffraction(XRD)analysis,thermogravimetric analysis(TGA),differential scanning calorimetry(DSC),and redispersibility to measure the quality and property changes.Under the same temperature and airflow rate,ultrasonic drying enhanced drying rates,resulting in at least a 50%reduction in drying time compared to hot air drying.The mean particle sizes of CNC from ultrasonic drying changed little with settling time,indicating good redispersibility.In addition,ultrasonic dried CNCs exhibited good stability in aqueous solutions,with the zeta potentials rang-ing from-35 to-65 mV.Specific energy consumption and CO_(2) emissions of various CNC drying technologies were evaluated.Energy consumption of ultrasonic drying is significantly reduced compared to other drying technologies.Moreover,the potential CO_(2) emissions of the fully elec-trified ultrasonic drying could be net zero if renewable electricity is used.
基金
supported by the United States Department of Energy(grant No.DOE-DE-EE0009125).
