Hard‐ and softwood residues (from birch and pine respectively) of forestry, pulp, and paper industries (e. g. sawdust, branches) were used to prepare biochar, which was then oxidized using nitric acid to produce catalytic carboxylic acid functionalized biochar. This oxidized biochar, ox–bc, in the presence of a co‐catalyst, showed excellent catalytic activity towards the cycloaddition reaction between CO2 and epoxides using mild conditions (CO2 pressure, 10 bar). No differences in catalytic activity were seen between the two types of oxidized biochar despite the hardwood ox–bc having a significantly higher surface area. The catalysts function through activation of the epoxide reagent via hydrogen‐bonding with carboxylic acid groups on the surface. The number of surface acid groups was reduced by reaction with 3‐aminopropyltriethoxysilane and the resulting material was inactive in the reactions studied. The ox–bc catalysts are sustainable, economic, and renewable alternatives for currently used heterogeneous systems and are also the first carbon‐based materials derived from biomass to exhibit good recyclability (over five runs) with a broad substrate scope for the production of cyclic carbonates from epoxides and CO2.

Crustacean shell waste is one of the most important chitin sources for commercial use due to its low price and high availability. The extraction of chitin from this residue relies on two removal steps: one for proteins and another one for minerals. Herein, we report a "solvent-free", one-pot process relying on mechanochemistry and aging to convert crustacean shells into chitin with high yields and low ash content. The extraction was performed on European Green Crabs, one of the world's most damaging invasive species, thus converting a serious environmental threat into a biomaterial opportunity. Successful chitin isolation of Green Crabs was achieved by milling of solid acids (i.e., citric, ascorbic, malic, succinic, and salicylic acid) for 10 to 30 min, while a combination of milling and aging was necessary for aqueous acids (i.e., hydrochloric and acetic acid). Milling, aging times, and shell to acid ratios were optimized, while the process could be scaled to 200 g of shell starting materials. This method required limited chemical and energy inputs, which were quantified by sustainability metrics. The process reported is a more sustainable approach for chitin production over the current industrial methods and has the potential to be extended to other chitin sources (e.g., lobster, shrimp, and insects).

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Exfoliation can be used to weaken and break van der Waals interactions within layered materials and produce small monolayered counterparts with remarkable properties. In the current study, liquid-phase exfoliation (LPE) using ultrasound and organic solvents is explored as a method to break down layered structures in biochars. Unfortunately, preferred solvents that can effectively disperse and stabilize the sheets produced during exfoliation often possess several health risks. In this work, we show that LPE in greener solvents can be used to access nanostructures of biochars to further improve the applications of this biobased material. Herein, pristine and oxidized biochars are exfoliated in a range of solvents to allow the identification of benign alternatives, which have been classified as nonhazardous or less hazardous by various solvent guides. The majority of biochar nanostructures produced consists of stacked nanosheets containing between two and eight layers with 15 nm thickness in average. Correlations between the LPE of biochars and different solvent parameters are established, and surface modification of biochars has potential to increase their exfoliation in more benign solvents. The LPE of oxidized biochars is more efficient in hydrogen-bond-accepting solvents due to the increased concentration of functional groups on their surface. Dispersions containing 0.20−0.75 mg/mL exfoliated oxidized biochars were obtained in solvents such as polyethylene glycols and ε-caprolactone. The LPE of pristine biochars in dimethyl carbonate and ethyl acetate gives similar yields to the most commonly used solvent for this process, N-methyl-2-pyrrolidone.

Functionalized biochars, renewable carbon materials prepared from waste biomass, can catalyze transformations of a range of oxygen-containing substrates via hydrogen-bonding interactions. Good conversions (up to 75.2 %) to different O-heterocycles are obtained from ring-closing CÀ O/CÀ O metathesis reactions of different aliphatic ethers under optimized conditions using this heterogeneous, metal-free, and easy separable catalyst. The diversity in the sorts of O-containing feedstocks is further demonstrated by the utilization of functionalized biochar to promote the esterification of terpene alcohols, an important reaction in food and flavor industries. Under the optimized conditions, full conversions to various terpene esters are obtained. Moreover, both of the reactions studied herein are performed under neat conditions, thus increasing the overall sustainability of the process described.

environmental challenges, address the UN SDGs, and achieve a sustainable future for us all. Collectively, we can follow the lead of the many women visionaries who have alerted us of the urgency to protect our planet, from Rachel Carlson to Wangari Maathai and Jane Goodall. 15 On 2022 International Women's Day, we celebrate the achievement of all women in sustainable chemistry and engineering and raise awareness and call all for action to #BreakTheBias. 46 Amy S. Cannon, Beyond Benign orcid.org/0000-0002-7567-5219