Hydroxyl-Enriched Core/Shell Carbon Nanotubes for Catalytic Hydrolysis of Regenerated Cellulose to Glucose

Abstract

A hydroxyl-enriched core/shell structured carbon nanotube (CNT/C-OH) is prepared by the method of hydrothermal carbonization (HTC) as a catalytic accelerator to induce highly efficient hydrolysis of regenerated cellulose to glucose. By use of sonication with high sound intensity, the carbon source (namely glucose) is homogeneously dispersed with CNT to form a colloid. Accordingly, a high-quality CNT/C-OH with a hydroxyl-enriched coating layer is produced in the following HTC. The oxygen mass content of the shell is up to 16.38%. A great deal of hydroxyl groups contribute to the CNT/C-OH having a strong affinity to adsorb with the regenerated cellulose and thus to enhance its hydrolytic ability to convert to sugar. In a low-acid aqueous system with CNT/C-OH, the cellulose conversion and the glucose yield reach 94.62 and 78.82%, respectively. A good reusability of CNT/C-OH is also found in multiple steps of hydrolysis of the regenerated cellulose to sugar.

Formation Mechanisms of Hydroxyl-Rich Carbon Layers on Carbon Nanotube Surfaces for Promoting the Hydrolysis of Cellulose to Sugar

“…That is because the hydroxyl-rich carbon layer-coated CNTs provided rather strong adsorption to break the aggregate structure of cellulose. Accordingly, the acid catalyst can more easily enter the inside of cellulose to enhance the hydrolytic responsiveness of the glycosidic bond. ,,− These results showed that the hydroxyl-rich carbon layer on the surface of CNTs played an important role in the hydrolysis of cellulose to sugar.…”

“…The utilization rate of the carbon source and the quality of the coating on the CNTs are not high. In our previous work, 34 with the aim to strengthen the dispersion between the carbon source and CNTs and then enhance the utilization of the carbon source, a method driven by sonication with high sound intensity was tried to treat the mixture of CNTs and glucose. Accordingly, it can be found that the amount of associated carbon spheres obviously decreases during the coating of CNTs in HTC.…”

“…The quality of the carbon layer coating on the surface of CNTs was improved as well. However, because glucose was proved not to adsorb on the surface of pure CNTs with large quantity, , it seems that only the sufficient dispersion between glucose and CNTs is not enough to completely control the formation process of the hydroxyl-rich carbon layer in HTC. Understanding of the essential principle to improve the utilization efficiency of glucose as a carbon source for the formation of the hydroxyl-rich carbon layer coating on CNTs with high quality in HTC is still not clear and even shows some disputes.…”

An Active Bio-Based Food Packaging Material of ZnO@Plant Polyphenols/Cellulose/Polyvinyl Alcohol: DESIGN, Characterization and Application

“…To the O1s spectrum of Figure 3 c, three peaks at the binding energies of 531.0, 532.3 and 533.1 eV were also obtained after fitting. The first one is attributed to the lattice oxygen of ZnO, and the last two correspond to C−O−H and C−O−C bonds originating from cellulose, PPL and PVA [ 16 , 48 , 49 , 50 , 51 ]. The Zn2p spectrum showed a typical doublet peak at 1021.9 and 1045.0 eV, which were Zn2p 3/2 and Zn2p 1/2 of divalent Zn element, respectively.…”

In situ bifunctional solid acids bearing B–OH and –COOH groups for efficient hydrolysis of cellulose to sugar in a pure aqueous phase

“…In our previous research, 10,11,[43][44][45][46][47] we embarked on the research endeavor to develop cellulase-mimetic catalysts by using a rational design approach to introduce strong adsorption with cellulose into solid catalysts. Utilizing the strong adsorption to break down the aggregation structure of cellulose enhances the hydrolytic responsibility of glycosidic bonds particularly instead of the function of traditional strong acids.…”