Polymer upcycling of municipal solid cellulosic waste by tandem mechanical pretreatment and maleic acid hydrolysis
Munmun Basak, Emma Gandy, Lucian A. Lucia, Lokendra Pal
Abstract
Significant accumulation of waste biomass in landfills and greenhouse gas emissions has triggered our current comprehensive approach to depolymerize cellulose-rich waste disposable paper cups (WDPCs) into cellulose nanocrystals (CNCs). This work develops a pathway for high-yield, greener, and low-cost CNC production by alkali and maleic acid hydrolysis of recovered fibers following mechanical separation and recycling of WDPCs. The X-ray diffraction confirms polymorphic transformation of CNCs from cellulose I to cellulose II crystal allomorphs with crystallinity indices ranging from 57%–64%. Rice-like CNCs with diameters ranging approximately from 5–10 nm and length 45–80 nm are determined by transmission electron microscopy. The obtained CNCs have good thermal stability and suspension properties. The yield of recovered cellulosic fibers from WDPCs is higher than 85% and CNCs is 70%–75%. The isolated CNCs can be used to develop biodegradable films and barrier coating in packaging to replace non-biodegradable petrochemical-plastics, enabling the transition to a circular economy.