Preparation of nanofibrillated cellulose and nanocrystalline cellulose from surgical cotton and cellulose pulp in hot-glycerol medium
A simple and green method for the preparation of nanofibrillated cellulose (NFC) by heating surgical cotton in glycerol is demonstrated as an alternative to the existing mechanical degradation method. The heat treatment of cotton in the presence of 9% w/w sulphuric acid in glycerol (1 M), under relatively milder conditions than those reported in the literature in the absence of glycerol, resulted in the formation of nanocrystalline cellulose (NCC) due to extensive hydrolysis of the amorphous segments. The method reported offers certain unique advantages in the preparation of NFC such as high yield (71%) and much easier post-processing compared to the mechanical degradation method of preparation of NFC. It also offers certain unique advantages in the preparation of NCC such as relatively high yield (56%), the use of lesser quantity of sulphuric acid as well as elimination of the quenching of the reaction through the addition of excess water to the reaction mixture. The residual ‘green solvent’, separated by decantation or centrifugal separation, post-reaction, could be reused for several cycles after filtration with activated carbon. A simple utility of the NCC prepared as reinforcing additive to cement is demonstrated. The addition of 1% (w/w of cement) of NCC and tetraethylorthosilicate modified NCC enhanced the workability of cement mortar and the compressive strength of cured cement composite in sharp contrast to the use of microcrystalline cellulose that required 10% (w/w) for the same enhancement in strength but with poorer workability.
KeywordsAgricultural biomass Nanocellulose Surface modification Filler Cement composite Workability
The authors thank the Department of Materials and Metallurgical Engineering, IIT Madras for extending the TEM facility and Prof.S. Ramaprabhu, Department of Physics, IIT Madras for enabling zeta potential measurements and dynamic light scattering experiments. The authors thank Prof. K. Ramamurthy of the Department of Civil Engineering, IIT Madras for guiding the work on cement-reinforcement studies and testing. The work presented here is a part of Indian patent application (201841019186) filed by the authors. This work was supported by IIT Madras.
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Conflict of interest
The authors declare no competing financial interests.
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