Growth promotion of microalgae Dunaliella bardawil and disruption of microcrystalline cellulose structure by the interactions between cellulose hydrogen bonds and algae exudates: Microcrystalline cellulose in the algae culture medium

We reported a novel method to promote the growth of microalgae Dunaliella bardawil (D. bardawil) and disrupt the structure of microcrystalline cellulose (MCC) by adding different amount of MCC to the growth medium (200 mL). The effect of MCC additive on the growth of D. bardawil was examined, and structure changes of MCC treated in the medium were investigated. The proper addition of MCC promoted the growth of D. bardawil by removing some growth inhibitors derived from algae exudates in the medium. Cell density of the algae got a maximum increase of about 20% when MCC was added at 1.5 g/L. After treatment in the medium, MCC had the maximum reduction 12.5% in crystallinity (CrI), and polymerization degree (DP) was reduced to the minimum 170 from 209, leading to a lower thermal stability. All the above changes of treated MCC can be attributed to the combined effects of algae exudates and inorganic ions in the medium. We believe that this study has potential value in making the two biological resources more suitable for utilization. (C) 2012 Elsevier Ltd. All rights reserved

Cellulose-derived carbon bearing -Cl and -SO3H groups as a highly selective catalyst for the hydrolysis of cellulose to glucose

A solid acid catalyst (HA-CC-SO3H) was synthesized by the sulfonation of amorphous carbon derived from the carbonization of dilute hydrochloric acid-pretreated microcrystalline cellulose. It was found that Cl-ions are grafted onto the cellulose-derived carbon and affect the composition and structure of the carbon carrier during the carbonization process. The electrons of the aromatic carbons transfer to -Cl and -SO3H groups, which influence their electronic state. In the cellulose hydrolysis process, the active electronic states make the -Cl groups more liable to form hydrogen bonds with cellulose, and the -SO3H groups with stronger acidity easily break the glycosidic bonds of cellulose to produce glucose. The HA-CC-SO3H catalyst exhibits excellent glucose selectivity (95.8%) at a moderate temperature (155 °C) under hydrothermal conditions. This journal is ? the Partner Organisations 2014

Selective Decomposition of Cellulose into Glucose and Levulinic Acid over Fe-Resin Catalyst in NaCl Solution under Hydrothermal Conditions

National Natural Science Foundation of China [21176203]The selective decomposition of microcrystalline cellulose (MCC) by Fe-resin (a modified Dowex 50 by cation-exchange) solid catalyst in 5 wt % NaCl solution under hydrothermal conditions has been investigated. The conversion of MCC increases from 24.4% (without catalyst) to 90.9%, and the yield of glucose and levulinic acid (LA) increases from 0.6% and 1.1% (without catalyst) to 38.7% and 33.3%, respectively, under 200 degrees C for 5 h. The role that Fe-resin/NaCl played in the system is discussed in detail: NaCl could disrupt the hydrogen-bond matrix among cellulose fibers to change highly crystalline cellulose into an amorphous form; Lewis acids on the Fe-resin further boost the depolymerization of amorphous cellulose into water-soluble sugars (WSSs); Fe ions on Fe-resin progressively released into NaCl solution are beneficial to the conversion of WSSs to glucose and LA. A three-step degradation scheme reflecting the main pathways of MCC degradation in the reaction is proposed