polymers Article Recycling Waste Cotton Cloths for the Isolation of Cellulose Nanocrystals: A Sustainable Approach Siti Hajar Mohamed 1 , Md. Sohrab Hossain 1,* , Mohamad Haafiz Mohamad Kassim 1, Mardiana Idayu Ahmad 1 , Fatehah Mohd Omar 2, Venugopal Balakrishnan 3 , Muzafar Zulkifli 4 and Ahmad Naim Ahmad Yahaya 4,* 1 School of Industrial Technology, Universiti Sains Malaysia, Penang 11800, Malaysia;
[email protected] (S.H.M.); mhaafi
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[email protected] * Correspondence:
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[email protected] (A.N.A.Y.); Tel.: +60-46535206 (M.S.H.); +60-65512146 (A.N.A.Y.); Fax: +60-46533678 (M.S.H.); +60-65512001 (A.N.A.Y.) Abstract: There is an interest in the sustainable utilization of waste cotton cloths because of their enormous volume of generation and high cellulose content. Waste cotton cloths generated are disposed of in a landfill, which causes environmental pollution and leads to the waste of useful resources. In the present study, cellulose nanocrystals (CNCs) were isolated from waste cotton cloths Citation: Mohamed, S.H.; collected from a landfill. The waste cotton cloths collected from the landfill were sterilized and Hossain, M.S.; Mohamad Kassim, cleaned using supercritical CO2 (scCO2) technology. The cellulose was extracted from scCO2-treated M.H.; Ahmad, M.I.; Omar, F.M.; waste cotton cloths using alkaline pulping and bleaching processes.