Environmental Impact Assessment of Chitin Nanofibril and Nanocrystal Isolation from Fungi, Shrimp Shells, and Crab Shells

Abstract

Chitin nanoparticles are responsible for the outstanding mechanical properties found in the exoskeletons of crustaceans and are finding applications in many scientific and technological fields. Following a Circular Economy approach, diverse biomass wastes can be valorized to be reintroduced back into the economic cycle while preventing biowaste landfill upon isolation of chitin nanoparticles. Novel environmentally sustainable paths over the conventional chitin nanoparticle extraction involving harsh acid-hydrolysis treatments from crustacean shells have been recently proposed. In particular, fungi emerge as an attractive alternative provided the demineralization process with acids such as HCl is circumvented. In spite of this recognized virtue, no works have quantified the environmental impacts of these processes. The life-cycle assessment methodology is applied to close this gap and quantify the cradle-to-gate impacts of chitin nanofibril extraction from fungi. The results are compared to conventional chitin nanocrystal hydrolytic isolation processes from shrimp shells, chitin powder, and crab shells, together with sulfuric-acid-induced hydrolysis of microcrystalline cellulose to cellulose nanocrystals. Eighteen impact indicators are analyzed scaling-up laboratory quantities into processes treating 1 kg of biowastes. A global warming potential value of 18.5 kg•CO 2 -equiv per 1 kg of chitin nanofibrils is obtained, well below the 906.8, 105.2, 543.5, and 177.9 kg CO 2equiv•kg −1 values obtained for chitin nanocrystals from shrimp shells, chitin powder, crab shells, and cellulose nanocrystals, respectively. A sensitivity analysis shows a 10.1−62.6% impact decrease to a minimum value of 14.7 kg CO 2 -equiv•kg −1 for chitin nanofibril isolation from fungi considering 95% recirculation of the solvent/NaOH, highlighting the environmentally sustainable character of chitin nanofibril extraction from fungi. The potential application of chitin nanoparticles into environmentally sustainable materials and devices is explored. These results provide novel cues for the environmentally friendly synthesis of nanochitin, guiding the implementation of sustainable approaches in the field of biomass nanoparticles.

Chitin Nanofibrils from Fungi for Hierarchical Gel Polymer Electrolytes for Transient Zinc‐Ion Batteries with Stable Zn Electrodeposition

“…[ 30 ] Thus, we conclude that the mild ChNF extraction process here applied does not disrupt the hydrogen bonding within the chitin crystallites (as the crystalline order is kept), ensuring a higher quality of nanofibrils when compared with nanochitin extracted from crustacean exoskeletons, which require extensive demineralization and deproteination steps with notable environmental burdens. [ 18 ]…”

“…[30] Thus, we conclude that the mild ChNF extraction process here applied does not disrupt the hydrogen bonding within the chitin crystallites (as the crystalline order is kept), ensuring a higher quality of nanofibrils when compared with nanochitin extracted from crustacean exoskeletons, which require extensive demineralization and deproteination steps with notable environmental burdens. [18] As chitin chains interact via H-bonding between amine and carbonyl groups depending on the crystalline polymorphs (namely 𝛼-, 𝛽-, and 𝛾-chitin), FTIR spectroscopy is a quick yet accurate technique to determine the packing mode of chitin chains. [29] The FTIR spectrum in Figure 2f shows the characteristic absorption bands of chitin, with a broad band in the 3650-3200 cm −1 region originating from the ─OH stretching at 3434 cm −1 and the ─NH stretching at 3276 cm −1 , together with the bands at 2911 and 2841 cm −1 from the ─CH groups, and the amide I, amide II and amide III bands centered at 1628, 1556, and 1315 cm −1 , respectively.…”

“…[ 16 ] Importantly, chitin nanofibrils (ChNFs) are very easily extracted from fungi in comparison with the typical crustacean resources, [ 17 ] opening the path toward high‐performance green biocolloids. ChNF isolation solely produces 14.7–18.5 kg CO 2 ‐equiv·kg −1 , [ 18 ] well below the 177.9–906.8 kg CO 2 ‐equiv·kg −1 generated during conventional cellulose nanocrystal or chitin nanocrystal extraction. In addition, the nanoscale diameter and microscale length of these biocolloids result in high aspect ratios that enable their interaction, deformation, and ultimately entanglement into gels at low concentrations, [ 19 ] making them highly attractive to obtain GPEs with large factions of ionic species and high ionic conductivity values.…”

Structural Color from Cellulose Nanocrystals or Chitin Nanocrystals: Self-Assembly, Optics, and Applications

“…However, these β-glucans are reportedly still susceptible to hydrolysis at highly acidic conditions . Biological processes can also be employed to purify chitin in a more sustainable manner that minimize energy and water usage, though such processes are typically time-consuming. ,, Regardless of the method employed, purified chitin is found to be partially deacetylated, and therefore differs from the idealized molecular structure depicted in Figure a. The degree of acetylation (DA), which describes the proportion of amides relative to amines, is typically 90–95%, as identified by solid state NMR spectroscopy, infrared spectroscopy or conductometric titration.…”

Techno-Economic Assessment of Chitin Nanofibrils Isolated from Fungi for a Pilot-Scale Biorefinery

“…Considering ChNFs from fungi meet current market needs in terms of ease of isolation, environmental sustainability, and multifunctional properties, , fungi in general, and mushrooms in particular, emerge as a potential source for chitinous material development. , The current low-end use of fungal biomass waste, i.e., fungi that are discarded because they are unfit for consumption, offers a starting point to develop a bioeconomy not competing with the food supply. Projects aimed at the valorization of biological wastes from the food industry can improve their economic competitiveness while reducing their environmental impacts.…”