Upcycling of ligno-cellulosic nutshells waste biomass in biodegradable plastic-based biocomposites uses - a comprehensive review

Biomass and agricultural wastes have increased exponentially and are significant concerns resulting in further environmental and societal issues through the accumulation and burning of waste. Waste burning emits fumes, which release and increase greenhouse gas emissions into the atmosphere. During the production and harvesting of nuts, nutshell waste can account for 20 to as much as 80 wt.% of the total production volume, leaving a considerable amount to accumulate and be underutilized. China and the USA are the most significant producers of nutshells globally, of which, peanuts, walnuts, and almonds are the highest produced. In addition to biomass waste, plastic pollution causes the contamination of land and marine environments and the leaching of toxic substances during their decomposition under the action of environmental conditions. Interest in biodegradable polymers, their investigation, and production have quickly risen recently. This addresses the challenges of the linear economy cycle and offers a solution to waste management by improving degradation rates and applications. As such, biodegradable and biobased polymers can decrease energy consumption by 65 % and greenhouse gas emissions by 35 to 80 %. Therefore, this timely review focuses on using nutshell wastes such as walnuts, almonds, peanuts, pecan, pistachios, and hazelnut shells as fillers in biodegradable polymers and fabricating sustainable composites via various processing techniques. Current uses and environmental considerations of nutshell waste-based composites have been discussed based on feasibility and economic impact.