Approach towards sustainable circular economy: waste biorefinery for the production of cellulose nanocrystals.

The rapid increase in solid waste along with urbanisation, especially arising from the industrial and agricultural sectors, sparks concern from the public regarding their adverse impact on human and environmental wellness. Therefore, waste biorefinery is the current interest that aligns with the concept of 'waste-to-wealth'. The conversion of waste into valuable products such as cellulose nanocrystals (CNCs) is an alternative method of circular waste management as CNCs have various applications. Their non-toxicity, biocompatibility, excellent mechanical strength, and load-bearing properties render them a good reinforcement agent for packaging films, sensors, and scaffolds. Nonetheless, the lack of studies on the comparison of waste sources and the complex parameters for the extraction of CNCs hinders the development of CNC extraction from waste products. This review paper compares and organizes the information from previously published scientific papers and reports on waste product sources, methods, parameters, and environmental effects of the derivation of CNCs from waste. Previously, no thorough reviews have been done closely on the sustainability aspect of CNC extraction from waste products. Through this review, it shows that there is a positive trend where novel CNC extraction routes are discovered to improve the yield, environmental friendliness, performance, and cost. However, most of the studies did not specify the environmental impacts of the extraction routes, limiting their feasibility for conventional applications. [ABSTRACT FROM AUTHOR]