Doctor of Philosophy (PhD)


Renewable Natural Resources

Document Type



Tar is inevitably produced from biomass thermochemical processes, and is often disposed as an industrial waste, leading to environmental pollution. As a result of its high carbon content, tar was expected to be a promising precursor for manufacturing carbon materials. Consequently, low-cost porous carbon nanofibers (CNFs) using tar, polyacrylonitrile (PAN), and silver nanoparticles was fabricated through electrospinning and subsequent stabilization and carbonization processes. The continuous electrospun nanofibers were obtained with diameters ranging from 392 to 903 nm. The addition of biomass tar resulted in increased fiber diameters, reduced thermal stabilities, and slowed cyclization reactions of PAN in the as-spun nanofibers. After stabilization and carbonization, the produced CNFs showed more uniformly sized and reduced average diameters. The CNFs exhibited high specific surface areas (>400 m2/g) and microporosity. These porous features increased the exposures and contacts of silver nanoparticles to the bacteria, leading to excellent antimicrobial performances of as-spun nanofibers and CNFs. A new strategy is thus provided for utilizing tar as low-cost precursor to prepare functional CNFs and reduce environmental damage by direct disposal of tar. Additionally, nanocellulose, was used as an environmental friendly and high performance additive in drilling fluids for improving rheological and fluid filtration properties. Two types of nanocellulose, including cellulose nanocrystals (CNCs) and cellulose nanofibers (CNFs), were applied in the drilling fluids. The effects of nanocellulose dimensions and concentrations on the rheological and filtration properties of drilling fluids were investigated. With half of the bentonite (10 lb/bbl) replaced by a small fraction of nanocellulose (0.35-3.50 lb/bbl), the resultant low-solid drilling fluids showed excellent shear thinning behavior and the fluids’ viscosity, yield point, and gel strength increased with the concentrations of nanocellulose. On the other hand, the addition of nanocellulose reduced the fluid loss of the fluids under high temperature and high pressure (HTHP) conditions, demonstrating potential for HTHP well applications. Additionally, the CNCs and CNFs behaved differently in the rheological and fluid filtration properties attributed to their distinct morphologies. This study promoted the use of novel renewable biopolymer additives in drilling fluids with enhanced performance and advantages of low cost and ecologically friendly.



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Committee Chair

Wu, Qinglin