Opportunities from Renewable Resources: From biobased chemicals to biomaterials

Renewable resources and materials are considered as sustainable alternatives to their petroleum-derived counterparts which are often associated with negative social and environmental impact. In particular, where renewable resources occur as a by-product or waste as a consequence of primary and secondary processing, they can be viewed as a potential source of carbon neutral biobased chemicals, materials and (bio)energy through a process termed valorization. This thesis presents the valorization of unavoidable food supply chain wastes (UFSCW), namely, pea-, ginger- and agricultural straw-waste to afford biobased chemicals, materials and (bio)energy. Pea and ginger wastes were successfully defibrillated in to microfibrillated celluloses (MFC) via acid-free microwave hydrothermal treatment as evidenced by changes in IR, TGA, 13C CPMAS NMR, SEM, TEM, XRD, CrI and their ability to form hydrogels. The hydrolysate was rich in sugars, organic acids and, interestingly, starch (only for ginger waste). The effect of extrusion on pea waste gave higher CrI (approx. 1%-15%) and thermal stability (around 1-11oC), reduced lignin and hemicellulose content, narrower fibril width (about 0.4-3.3 nm), better water holding capacity (5 to 40 % higher) and higher surface area compared (approx. 7-20 m2/g) with their non-extruded counterparts. Ginger essential oils were successfully isolated in good yield (heptane; ~4%) with a composition similar to industrial grade ginger oil. Microwave pyrolysis of ginger afforded hydrochars (20 - 24.5 MJ kg−1) and bio-oils of variable quality dependent on the processing conditions. Bioboards (maximum IBS:0.25 N/mm2) were successfully manufactured from agri-straws and biosilicate binders, and initial attempts to produce foam materials, as an inner layer of a structural insulation panel (SIP) are reported. Preliminary attempts to increase hydrophobicity via silanization are reported. In conclusion, this thesis shows that biorefineries that deliver chemicals, materials and (bio)energy can be envisaged from valorization of pea, ginger and agri-straw UFSCWs.