Renewable Materials from Renewable Resources

Renewable resources related to biomass, waste materials and recycled materials are an important concept in the principles of green chemistry, development of biorefineries and sustainability development. This thesis reports the repurposing of renewable resources which included wheat straw, biomass ash, waste cardboard (paper) and paper de-inking residues (DIR) to extract, synthesize and produce potentially high value chemicals, materials and composites.
Biosilicate solutions were successfully extracted from biomass ash including wheat straw ash and miscanthus ash with aqueous potassium hydroxide solutions. Systematic analyses had been applied on the extraction of biosilicate solutions to obtain different types of silicate solutions for further applications of binder and mesoporous materials. Biosilicate solutions extracted from miscanthus ash were utilized as binders to make bioboards, whilst biosilicate solutions extracted from wheat straw ash were utilized as a silica resource to synthesize biobased mesoporous materials, namely bio-MCM-41 and bio-SBA-15. N2 porosimetry analysis revealed that mesoporous silica made from biosilicate solutions gave a surface area of bio-MCM-41 of >1000 m2 g-1 and a surface area of >800 m2 g-1 for bio-SBA-15. XRD, SEM and TEM analyses for both bio-MCM-41 and bio-SBA-15 revealed significant ordering pores, structure and the hexagonal arrays. Different kinds of renewable resources including wheat straw, pea pod waste and paper de-inking residue with the binder of biosilicate solutions and other chemical additives such as protein and starch were processed to bioboards. Also, wheat straw powder was added into cardboard/paper sheets to decrease the cost of paper manufacture and to improve mechanical properties. De-waxed wheat straw cardboard/paper sheets was successfully incorporated in to paper pulp to give a tensile index of 30-34 Nm/g similar with respect to conventional cardboard paper (tensile index of 30-32 Nm/g). A brief study to elicit sugars to the surface of cardboard/paper thus producing an in-situ sticky surface using low temperature microwave irradiation was conducted. Although it’s not conclusive, an aqueous fraction was expelled that contains organic matter (based on C-H stretch absorption bands noted in FT-IR), which may be due to sugars.