Date of Award
Doctor of Philosophy (PhD)
Chemistry & Biochemistry
James. W. Lee
John R. Donat
Lesley H. Greene
Through the innovative technique of biochar post-production surface oxygenation by ozonization, we were able to improve certain properties of biochar. In project one, the incubation of an insoluble phosphate rock material (hydroxyapatite) with the wet ozonized pine 400 biochar and its filtrate resulted in a solubilization of 80 times more phosphate from hydroxyapatite (569.0 mg/L ± 6.4) compared to the pure water-hydroxyapatite control (7.2 mg/L ± 0.3). The ozonized biochar may provide a new possible way to unlock the phosphorus from insoluble phosphate mineral phases. The cation exchange capacity (CEC) is a key property of biochar when used as a soil amendment. In project two, using a high surface area biochar (rogue biochar), we were able to increase the CEC by a factor of almost 10 times upon ozone treatment; a biochar with an initial CEC of 17.02 cmol/kg ± 0.63 was increased to 152.08 cmol/kg ± 4.06 upon ozonization. The process of biochar ozonization generated large amount of dissolved organic carbon (DOC) in the filtrate/wash. Previously discarded as waste, here we showed that these DOC, even at low concentrations, may be useful for some applications such as unlocking phosphate from phosphate rock material. In project four, the bioassay of ozonized biochar substances was conducted on soil bacteria Pseudomonas putida and freshwater cyanobacteria Synechococcus elongatus PCC 7942. Results indicated that ozone treatment of certain biochars reduced their inhibiting effect on some microorganisms. The biocontainment of genetically engineered (GE) cyanobacteria was recognized as a concern in case the latter was to break containment and escape into the environment. In project five, we tested the thermophilic nature of Thermosynechococcus elongatus BP1 as a biocontainment. A growth study in the greenhouse of Old Dominion University with genetically engineered (GE) Thermosynechococcus elongatus BP1-BY20 with biofuels producing genes showed that the GE T. elongatus BP1-BY20 did not actively grow in cool (15.44 oC to 25.30 oC) or warm season (31.42 oC to 36.27 oC) in the greenhouse. The thermophilic nature of T. elongatus BP1 may serve as a biosafety guarded mechanism during cool seasons but not so much during warmer seasons.
"Improvement of Biochar Through Ozonization and Biosafety of Genetically Engineered Cyanobacteria"
(2021). Doctor of Philosophy (PhD), Dissertation, Chemistry & Biochemistry, Old Dominion University, DOI: 10.25777/f83b-fy95