Valorization of hemp fibers into biocomposites via one‐step pectin‐based green fabrication process

Abstract

In this paper, an environmentally friendly fabrication process was reported to valorize hemp fibers into biocomposites through a pectin-based crosslinking reaction. In this water-based chemical approach, the hemp fibers were crosslinked via a transesterification process between pectin and lignin present in hemp fibers to produce hemp fiber composites in a one-step process. Our green process was advantageous over conventional processes that rely on the use of petroleum-based organic solvents and high reaction temperatures because water was used as the reaction solvent with a mild reaction temperature (70 C). Additionally, to further optimize this biocomposite fabrication process, one-factor analysis of variance study was carried out for investigating the main and interaction effects of the mass ratios of pectin to hemp fiber (1:5, 2:5, 3:5, 4:5, and 5:5) on the compressive strength and bulk density of the hemp fiber composite materials. In addition, the fabrication process was explored at different pH values to probe its versatility. The compressive strength of the assynthesized hemp fiber composite materials was observed to be dependent on the pH of the reaction conditions, indirectly confirming the formation of ester bonds between pectin and the lignin of hemp fibers via transesterification.

Eco-friendly fabrication of coco coir composites for hydroponic cultivation: a green chemistry approach

“…The degassed sample was again re-packed into the cylindrical quartz mold and left untouched for 2 hours at 70 °C in an oven to initiate the crosslinking process between pectin and coco coir. 69 The coco coir biocomposite was then carefully separated from the cylindrical quartz mold and left undisturbed for drying overnight at 100 °C. It was noteworthy to highlight that the additional vacuum treatment step proved to be a major improvement from the previous method because it drastically reduced the formation of air pockets within the samples.…”

“…A modified composite fabrication method from our previously reported study of hemp fibers was used to fabricate coco coir composite materials using high methoxyl pectin as the green crosslinker. 69 The one-step fabrication process was performed using a wide range of mass ratios of pectin to coco coir (1 : 5, 2 : 5, 3 : 5, 4 : 5, and 5 : 5) (Scheme 1 and Table S1 in the ESI †). Under basic conditions, the methyl carboxylate functionalities of pectin were expected to form covalent bonds with the phenol/ phenoxide moiety of lignin on coco coir via transesterification.…”

“…Under basic conditions, the methyl carboxylate functionalities of pectin were expected to form covalent bonds with the phenol/ phenoxide moiety of lignin on coco coir via transesterification. 56,[69][70][71] For example, coco coir composites with a 2 : 5 mass ratio of pectin to coco coir were made by adding 4 g of coco coir to 16 g of a 10 wt% pectin solution (or 1.6 g of pectin) under constant stirring until a consistent slurry was attained. 3 mL of 1 M NaOH solution was then added dropwise using a Pasteur pipet to the coco coir slurry until a paste-like consistency was reached.…”