| dc.description.abstract | This work utilizes brewers spent grain (BSG) as a low-cost feedstock for the development of a novel processing technique for producing high yield hydrogel polymers from high protein lignocellulosic biomass. BSG accounts for approximately 85% of the solid waste generated by breweries, resulting in an annual global production of 39 million tons per year. The primary limitation preventing adoption as feedstock for bioconversion is it moisture content of 80% significantly increasing it’s transportation and drying cost. Due to breweries high volume of BSG’s production the majority ends up in landfills. A novel processing technique was developed to valorize BSG into functional materials (BSGHP). The final BSGHP, created by a combination of mechanical and chemical pretreatment, followed by wet fractionation, and subsequent secondary treatment and mechanical post treatment before recombination, was characterized to determine potential applications.
The subsequent processing techniques were evaluated at final coagulation pH’s of 3.5 and 3.8 to determine how coagulation pH effects BSGHP performance. The BSGHP hydrogel network can be described as a naturally derived, mixed interpenetrating matrix composed of both physical and chemical crosslinks, in which cellulose fibers, proteins, and lignin rich components collectively contribute to network formation and structural integrity. Due to their amphiphilic nature, dissolved phenolics provide hydrophobic properties that counteract fibrillated celluloses hydrophilic nature, thereby increasing the lifespan of BSGHP when undergoing degradation. The dual entanglement and partial cross linking between the cellulose fibers and microfibrillated cellulose within the BSGHP matrix,
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creates structural reinforcement, enabling progressive load transfer and preventing structural collapse. Based on mechanical analysis, BSGHP is best suited as a replacement for cork-based materials such as protective packaging and structural paneling, due to its higher compressive strain deformation and superior energy adsorption capability.
The coagulation pH was also adjusted to 4.5 for evaluation of the BSG matrix base as a hydrogel-controlled release fertilizer (CRF). The 4.5 pH BSG-controlled release fertilizer (CB-CRF) acted as a control and was compared against a formulation containing a 2:1 ratio of gelatin and kappa carrageenan, comprising 14 wt% of the total gelatin kappa carrageenan blend BSG CRF (GKB-CRF). Both CRFs were subjected a 30 day nutrient-release study, along with a 15 day soil moisture content study, and a 15 day soil pH leachate study. Soil leachates were analyzed for nitrogen, phosphorous, and potassium concentrations on Days 3, 5, 10, 15, and 30 for the slow-release study and Days 3, 6, 9, and 15 for the soil moisture content and soil pH studies. The additives in GKB-CRF resulted in greater microbial activity leading to greater nutrient mineralization but faster degradation. Whereas the CB-CRF exhibited more linear nutrient release profile, consistent with those reported for CRFs in the literatures, while retaining much of its nitrogen content after the 30 days period. Both CRFs were determined to be suitable bases for a hydrogel-CRF matrices with low solubility of phosphorous and potassium amendments added. However, CB-CRFs appears more suitable for extended life-cycle crops like tomatoes and wheat, whereas the GKB-CRFs are better suited for short life-cycle crop production like spinach and radishes. | en_US |
