Univ. Grenoble Alpes, LRP, F-38000 Grenoble, France; CNRS, LRP, F-38000 Grenoble, France.
Univ. Grenoble Alpes, LRP, F-38000 Grenoble, France; CNRS, LRP, F-38000 Grenoble, France.
Carbohydr Polym. 2015 Jun 25;124:66-76. doi: 10.1016/j.carbpol.2015.01.073. Epub 2015 Feb 12.
This study investigates for the first time the behaviors of starch and cellulose nanocrystals (SNC and CNC) suspensions which are simultaneously subjected to pressure, shear flow and ultrasound (US) during cross-flow ultrafiltration. This multi-forces process was characterized from macro-scales to nano-scales, with a custom designed "SAXS Cross-Flow US-coupled Filtration Cell". In addition, rheological behaviors of SNC samples at different concentrations/temperatures have been investigated. In both cases (ultrafiltration of SNC and CNC suspensions), better performances were observed with US. The in-situ SAXS measurements revealed that for SNC suspensions, no structure change occurred at the length scales range from 10 to 60nm in this multi-forces process, while CNC particles exhibited an ordered arrangement within the concentrated layer during the same process. SNC particles accumulated on the membrane surface forming a "fragile" concentrated layer which was removed very quickly by subsequent applied US. In contrary, the CNC particles accumulation was very severe, the additional ultrasonic force led to a disruption but not a totally removal of the CNC concentrated layer.
这项研究首次考察了淀粉和纤维素纳米晶体（SNC 和 CNC）悬浮液在错流超滤过程中同时受到压力、剪切流和超声（US）作用的行为。该多力过程从宏观尺度到纳米尺度进行了表征，使用了定制的“SAXS 错流 US 耦合过滤池”。此外，还研究了不同浓度/温度下 SNC 样品的流变行为。在这两种情况下（SNC 和 CNC 悬浮液的超滤），超声都表现出更好的性能。原位 SAXS 测量表明，对于 SNC 悬浮液，在多力过程中，长度范围从 10nm 到 60nm 的范围内没有发生结构变化，而 CNC 颗粒在相同过程中表现出在浓缩层内的有序排列。SNC 颗粒在膜表面聚集形成“脆弱”的浓缩层，随后施加的 US 很快将其去除。相反，CNC 颗粒的聚集非常严重，额外的超声力导致 CNC 浓缩层的破裂而不是完全去除。
