Single and Mixed Feedstocks Biorefining: Comparison of Primary Metabolites Recovery and Lignin Recombination During an Alkaline Process

Abstract

Cannabis sp. and Euphorbia sp. are potential candidates as indoor culture for the extraction of their high value-added metabolites for pharmaceutical applications. Both residual lignocellulosic materials recovered after extraction are studied in the present article as single or mixed feedstocks for a closed-loop bioprocesses cascade. An alkaline process (NaOH 3%, 30 min 160 • C) is performed to separate the studied biomasses into their main components: lignin and cellulose. Results highlight the advantages of the multi-feedstocks approach over the single biomass in term of lignin yield and purity. Since the structural characteristics of lignin affect the potential applications, a particular attention is drawn on the comprehension of lignin structure alteration and the possible interaction between them during single or mixed feedstocks treatment. FTIR and 2D-NMR spectra revealed similar profiles in term of chemical functions and structure rather than novel chemical bonds formation inexistent in the original biomasses. In addition, thermal properties and molecular mass distribution are conserved whether hemp or euphorbia are single treated or in combination. A second treatment was applied to investigate the effect of prolonged treatment on extracted lignins and the possible interactions. Aggregation, resulting in higher molecular mass, is observed whatever the feedstocks combination. However, mixing biomass does not affect chemical structures of the end product. Therefore, our paper suggests the possibility of gathering lignocellulosic residues during alkali process for lignin extraction and valorization, allowing to forecast lignin structure and make assumptions regarding potential valorization pathway.

Potential for the valorisation of brewer’s spent grains: A case study for the sequential extraction of saccharides and lignin

“…To overcome this drawback, some samples of BSGs from different origins could be pooled and processed at a single high-capacity industrial site. However, our previous work has shown that this pooling was not strategic, but rather the opposite, especially for samples with fluctuating protein levels, which is the case in this study (Berchem et al, 2020).…”

“…Cellulose and hemicellulose contents were obtained on the basis of the quantification of the constituent monosaccharides, namely, glucose for cellulose, and the sum of arabinose, xylose, rhamnose, mannose and galactose for hemicellulose according to an adapted published protocol (Berchem et al, 2020). First, 100 µL of an internal standard solution (2-deoxy- d -glucose, 3 g L −1 ) was added to 900 µL of the Klason hydrolysate.…”

“…Polysaccharides (cellulose and hemicellulose) and lignin quantification. The lignin content of the solid residues was determined using the Klason procedure according to previous published protocols (Berchem et al, 2020). Practically, around 300 mg of the dried Soxhlet residue (depleted of extractives) was weighed and hydrolyzed using 3 mL of a 72% H 2 SO 4 solution during 1 h at 30°C.…”

“…rhamnose, mannose and galactose for hemicellulose according to an adapted published protocol (Berchem et al, 2020). First, 100 µL of an internal standard solution (2-deoxy-d-glucose, 3 g L −1 ) was added to 900 µL of the Klason hydrolysate.…”

Bringing Material Concepts into Conventional Biorefineries: Considerations of Sources, Preparations, and Applications of Lignin Nanomaterials

“…It generates alkali lignin (AL) under various temperatures with pH values generally higher than 10. Furthermore, there are numerous hydroxyl groups on the surface of AL, and etherified phenolic acid groups exist, which play an essential role in cross-linking. − In the current pulping industry, alkaline pretreatment is mainly used for the delignification of nonwood feedstocks, such as bagasse, wheat straw, and hemp …”