Phenolic adhesives are widely used in the production of engineered wood products due to their exceptional moisture and thermal resistance, chemical stability, and bonding strength. The phenolic adhesive is currently produced through condensation polymerization of two fossil fuel-derived compounds: phenol and formaldehyde. However, due to fluctuations in the price of phenol and formaldehyde with the price of oil, environmental and health issues associated with using these compounds, there is a strong interest in finding alternative renewables feedstocks. Lignin is a natural polyphenolic compound with excellent potential to substitute phenol in phenolic adhesive formulations. Lignin is produced as byproducts during pulp and bioethanol processes. On the other hand, biobased aldehydes such as glyoxal have recently gained a lot of attention for replacing the toxic formaldehyde in production of environmentally friendly wood products. In this study, a wide range of lignin samples from different resources (hardwood, softwood, wheat straw, and corn stover), and isolated via various processes (kraft, organosolv, soda, sulfite, and enzymatic hydrolysis), were used to formulate 100% lignin-based phenolic adhesives. In a separate work, formaldehyderee phenolic adhesives were also developed using either glyoxal or gossypol (a dialdehyde from cotton seed) in combination with phenol. Chemical, physical, and thermal properties of lignin samples and developed phenolic resins and adhesive were measured using advanced analytical techniques and appropriate ASTM standard test methods. Based on two-way ANOVA analysis results of shear strength data, a biorefinery corn stover lignin that had the highest p-hydroxyphenyl and p-coumaric acid content was the most suitable lignin for replacing 100% of phenol in phenolic adhesive formulation. In addition, the developed lignin-based adhesive (formulated with biorefinery corn stover lignin) showed similar dry and wet adhesion strengths as that of commercially formulated phenol resorcinol formaldehyde (PRF) adhesive. On weight basis, the formaldehyde consumption in the developed lignin-based adhesive was 50% lower than the formaldehyde used in phenol formaldehyde (PF) resin. Moreover, two formaldehyderee formulated adhesives using glyoxal and gossypol (renewable feedstocks) had very similar physico-chemical properties to phenol formaldehyde adhesive.

Yes / Energy saving is an important consideration in process design for low cost sustainable production with reduced environmental impacts (carbon footprint). In our earlier laboratory scale pilot plant study of catalytic wet air oxidation (CWAO) of phenol (a typical compound found in wastewater), the energy recovery was not an issue due to small amount of energy usage. However, this cannot be ignored for a large scale reactor operating around 140–160 °C due to high total energy requirement. In this work, energy savings in a large scale CWAO process is explored. The hot and cold streams of the process are paired up using 3 heat exchangers recovering significant amount of energy from the hot streams to be re-used in the process leading to over 40% less external energy consumption. In addition, overall cost (capital and operating) savings of the proposed process is more than 20% compared to that without energy recovery option.

Yes / Phenol is one of the most toxic and harmful pollutants in industrial wastewater streams, the removal of which is therefore of critical importance. The use of reverse osmosis (RO) systems as a means of treating wastewater is continuously growing. This research investigates the effect of operating parameters on the performance of five different multistage RO configurations coupled with a trickle bed reactor (TBR) using model-based simulation. The results were compared, and an analysis was then performed to identify which hybrid TBR and multistage RO arrangement rejected the most phenol content. The basis for comparison was four performance metrics of permeate concentration, rejection, recovery, and specific energy. The study found that the flow rate and concentration have little effect on the operation unless there is a concurrent increase of both. It was also found that the four-performance metrics used were interlinked and affect the quality and quantity of the final freshwater product.

The author was desirous of investigating the properties of "quinolineins" as compared with those of corresponding phthaleins. As there was no quinolinic acid available in the laboratory, an attempt was made to prepare it. It was found that most methods gave very small yields, with the exception of one. / Thesis / Master of Arts (MA)

Phenol formaldehyde (PF) is the oldest known synthetic polymer. This polymer has seen many applications throughout history, including jewelry, electric wire insulation, and resins used to make adhesives. Today, PF resins are still crucial components used in the wood products industry. These PF resins are formulated into adhesives used to make plywood and various other wood composite products. For example, in the United States, 90 % of the homes are still frame homes that use plywood for construction. The PF adhesives used to make these composites are formulated using agricultural waste products like walnut shells and corn-cob residue. These organic waste products act as fillers that reduce the cost, increase the viscosity, and affect the rheology of the fillers. Wheat flour is added as an extender to reduce cost and affect the tack of the adhesive. These organic fillers are lignocellulosic materials that are made of lignin, cellulose, and hemicellulose. Not much is known about the interactions of these organic fillers and the polymer resin. Rheological studies in our lab have shown that not all of the additions to the adhesive formulation are inert components in the adhesive. The steady-state flow curve analysis of PF adhesives revealed that there is a liquid structure change that occurs at high shear rate. This structure change is observed as a viscosity increase that occurs after applying a maximum shear rate of 4000 1/s. A rheological analysis was conducted to determine the source of this change, with individual components added to the resin. The PF base resin (with nothing added) has a Newtonian rheological behavior. When wheat flour is added to the resin, the overall viscosity increases, and shear thinning occurs at highe shear rates. There is no final viscosity change observed on with the addition of wheat flour. Adding corn-cob residue to the resin increased viscosity, led to some shear thinning at higher shear rates, and allowed the viscosity changes observed in the fully formulated adhesives. These experiments showed that the liquid structural changes that occur in the adhesives are attributed to the organic fillers. All organic fillers used in our studies, including corn-cob residue, walnut shell, almond shell, and Alder bark produce different levels of viscosity change in the PF adhesive formulations. These biomass materials have varying amounts of lignocellulosic content, particle size distributions, and particle shape. Among the fillers, corn-cob residue was shown to cause the most viscosity change compared to any of the fillers. Corn-cob residue is unique compared to the others because it has undergone acid digestion to convert its xylans to furfural. During the viscoelastic oscillation studies, the corn-cob residue filled adhesives showed that they developed network structures in response to a high shear rate that were not observed using the other fillers. With the discovery of these network structures, the next goal of this research was to correlate the effects observed on the rheometer to relevant adhesive application technology like high shear spraying. The corn-cob residue adhesive was sprayed at approximately 70,000 1/s compared to the 4000 1/s of rotational shear on the rheometer. The viscoelastic oscillation studies revealed that there was no network structure formation after high-shear spraying. Further, there was no change observed in the flow curve analysis after spraying the adhesive. This study showed that there are limitations when trying to correlate changes that happen in adhesives during spraying, where extensional forces dominate compared to shear forces. In future research, there is the opportunity to explore the effects of extensional deformation that occurs during the atomization of the adhesive, which will be more reflective of the changes that occur during spraying. / Doctor of Philosophy / Phenol-formaldehyde adhesives are crucial products in the home construction industry. These adhesives are used to make plywood that is used to build frame homes, which represent approximately 90 % of the homes in the United States. These phenol-formaldehyde adhesives are made using organic materials repurposed from agricultural waste products like corn cobs, walnut shells, almond shells, and tree bark. These products help to enhance the properties of the adhesive, reduce the cost, and reduce the amount of resin used. The goal of this research is to understand better the interactions between the adhesive and the organic fillers using rheology. Rheology is a field that studies how materials change and flow with applied external forces. This is an important field because it provides information on viscosity and viscoelastic behavior. Our research has shown that in response to high shear rates, the viscosity of these phenol-formaldehyde adhesives increases. Studying these changes can lead to a better understanding of how these materials change during industrial spraying. This understanding could lead to improved building adhesive materials in the home construction industry.

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