Biosorption of heavy metals by citrus fruit waste materials

Thesis (M.S.) University of Alaska Fairbanks, 2004Conventionally used processes for removing heavy metals from wastewater are usually either expensive, such as ion exchange, or inefficient, such as precipitation. An innovative technique that is both efficient and economical is biosorption, in which living and dead biomass can act as biosorbents through physical-chemical processes like ion exchange and micro-precipitation. Pectin, a structural polysaccharide present in plant cell walls, is similar to alginate, a molecule that is often responsible for the high metal uptake by algae. Based on the structural similarity between alginate and pectin, it was expected that pectin rich bio-wastes may be as good a biosorbent material as brown algae. A comparison between different pectin-rich materials showed high stability and metal binding capacity of citrus peels. Sorption isotherms for citrus peels showed higher metal uptake capacity at pH 5 compared to pH 3. Kinetic studies revealed the time required to reach equilibrium for lemon fruit waste (0.177 mm) was 20 min while for larger particles the time increased to 30 min-60 min. For lemon fruit waste, the content and pKa values of acidic groups were determined by using a pKa spectrum technique. Isotherm modeling was carried out by using Langmuir isotherms and pH sensitive modeling

Investigation of CO₂ sequestration options for Alaskan North Slope with emphasis on enhanced oil recovery

Thesis (M.S.) University of Alaska Fairbanks, 2006Carbon dioxide (CO₂), the main component of greenhouse gases, is released into the atmosphere primarily by combustion of fossil fuels like coal and oil. Due to a conspicuous lack of any CO₂ sequestration studies for Alaskan North Slope (ANS), the study of CO₂ sequestration options will open new avenues for CO₂ disposal options, such as viscous oil reservoirs and coal seams, on the ANS. This study focuses on the investigation of CO₂ storage options by screening ANS oil pools amenable to enhanced oil recovery, evaluating phase behavior of viscous oil and CO₂ mixture, and simulating enhanced oil recovery by CO₂ flooding, and migration of CO₂ in saline aquifer. Phase behavior studies revealed that CO₂ gas was partially miscible with West Sak, at the pressure closer to the reservoir pressure. Compositional simulation of CO₂ flooding for a five-spot West Sak reservoir pattern showed an increase in percent recovery with an increase in pore volume injected, but at the expense of an early breakthrough. Sensitivity analysis of CO₂ flooding project was found to be strongly dependent on the variables such as oil price and discount rate. Investigation of supercritical CO₂ injection in saline formation didn't increase temperature in the permafrost region