Hemp Stem Epidermis and Cuticle: From Waste to Starter in Bio-Based Material Development

Abstract

Nowadays, hemp farmers are facing an urgent problem related to plant stem disposal after seed harvesting. In this work, the commonly discarded epidermis and cuticle of hemp stems were valorized, turning them towards a sustainable recycling and reuse, contributing to the circular economy concept. Cellulose deprived of amorphous regions was obtained by a green process consisting of an ethanolic ultrasound-assisted maceration followed by mild bleaching/hydrolysis. The obtained hemp cellulose was esterified with citric acid resulting in a 1.2-fold higher crystallinity index and 34 ∘C lower Tg value compared to the non-functionalized hemp cellulose. Green innovative biocomposite films were developed by embedding the modified cellulose into PLA by means of an extrusion process. The structural and morphological characterization of the obtained biocomposites highlighted the functionalization and further embedment of cellulose into the PLA matrix. Attenuated Total Reflectance–Fourier Transform Infrared spectroscopy (ATR-FTIR) results suggested physical and chemical interactions between PLA and the organic filler in the biofilms, observing a homogeneous composition by Field Emission-Scanning Electron Microscopy (FESEM). Moreover, some increase in thermal stability was found for biocomposites added with 5%wt of the hemp cellulose filler. The obtained results highlighted the feasible recovery of cellulose from hemp stem parts of disposal concern, adding value to this agro-waste, and its potential application for the development of novel biocomposite films to be used in different applications.

Hemp Waste as a Substrate for Hermetia illucens (L.) (Diptera: Stratiomyidae) and Tenebrio molitor L. (Coleoptera: Tenebrionidae) Rearing

“…Aside from the use of seeds in nutrition [ 6 ], leaves and flowers can be a valuable source of bioactive cannabinoids while the remaining hemp by-products, i.e., the stalks, including fibres and shives, represent the majority of the plant′s dried weight and are low in cannabinoids [ 7 ]. Much of this fraction of plant biomass ends up as a low-value residue despite being a source of cellulose and other biomaterials [ 8 ]. Generally, processes that valorise agricultural residues are gaining an increasing attention due to economic and environmental consideration [ 9 ].…”

Particleboard Creation from Agricultural Waste Residue of Seed Hemp

“…Hemp was grown by sowing at the end of April (25-29 April) and harvesting at the end of September (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30). The harvesting date is comparable to the situation of real growing and production conditions, where the hemp threshing time is affected by the degree of ripeness of the crop, the weather (rain, humidity), and the availability of equipment for the threshing process.…”

“…At present, seed hemp farmers are facing an urgent problem related to plant stem disposal after seed harvesting, as the management of residue coming from the agricultural sector has become a global matter of concern. In Europe, agricultural waste processing for recovering bioactive compounds or developing innovative and green bio-based materials is in full agreement with the aim of the circular economy [24,25]. It is estimated that between 5 and 15 tonnes of hemp stems can be harvested per hectare of crops to obtain fibres and shives for manufacturing new products [26][27][28].…”

A waste hemp‐based biomass carbon aerogel with high fire‐resistance

“…Although an abundance of hemp resource is boasted in China, their exploitation is currently suboptimal, with the majority being incinerated for fuel or discarded as agricultural waste, resulting in inadequate economic and ecological returns. 1,2 Amid growing economic and energy demands, the harnessing of hemp biomass for energy applications represents a burgeoning trend for future development. 3 Significant progress has been made in the production of carbon materials from waste hemp stalks.…”

“…It exhibits a pronounced capacity for carbon dioxide absorption, positioning it as a highly promising non‐wooden fiber resource. Although an abundance of hemp resource is boasted in China, their exploitation is currently suboptimal, with the majority being incinerated for fuel or discarded as agricultural waste, resulting in inadequate economic and ecological returns 1,2 . Amid growing economic and energy demands, the harnessing of hemp biomass for energy applications represents a burgeoning trend for future development 3 .…”