Advanced oxidation of organic pollutants with TiO2 photocatalysts is limited due to the wide bandgap of TiO2, 3.2 eV, which requires ultraviolet (UV) radiation. When nanosized TiO2 is modified by carbon doping, charge recombination is inhibited and the bandgap is narrowed, allowing for efficient photodegradation under visible light. Here, we propose a flame spray pyrolysis (FSP) technique to create TiO2. The facile process of FSP has been successful in preparing highly crystalline TiO2 nanoparticles. Using the same procedure to deposit TiO2 onto biochar, the photocatalyst was doped by the carbonaceous material. The morphology, crystalline and electronic structure of the FSP TiO2 and TiO2-decorated biochar (TiO2-BC) were characterized by SEM, XRD, TGA, DLS, and diffuse reflectance UV-vis spectroscopy. Photocatalytic performance of TiO2 and TiO2-BC was investigated for model organic contaminants in an aqueous solution under UV and visible light, which will be compared to that of Degussa P25 TiO2 as a control.

Grape pomace (GP) is one of the most abundant and underutilized fruit-derived wastes. GP is generated during winemaking, occupying over 60% of the total solid winery wastes. GP may cause serious environmental problems if it is not properly handled. On the other hand, it is rich in valuable compounds that are worthy of recovery. Although research has been working on GP upgrading, the utilizations are limited to producing a single product (e.g., grape seeds oil or polyphenol powders), which leads to large volumes of secondary wastes left. Therefore, the goal of this study is to develop an integrated process for the comprehensive utilization of GP by the production of multiple value-added products and evaluate its economic feasibility at a commercial scale. First, the chemical composition of different industrial GPs was analyzed to lay the foundation for the process design. Based on the analyzed chemical composition, an integrated process was developed to produce grape oil, polyphenols, and biofuels from GP. In this process, GP was extracted by hexane to produce oil, followed by aqueous ethanol solution extraction to obtain polyphenols. The solid residue rich in structural carbohydrates was then pretreated by alkali to partially remove lignin and enzymatically hydrolyzed to produce monomer sugars. The produced sugars were used as feedstock to produce acetone, butanol and ethanol (ABE) through anaerobic fermentation. Under the optimized conditions, the process was able to produce 71.9 g crude oil, 322.8 g crude polyphenols (equivalent to 72.6 g gallic acid), and 20.7 g ABE from 1 kg dry GP. Besides the valuable products, the process co-generated a large amount (50% of input GP biomass) of secondary waste, which is rich in lignin. Therefore, we further converted the secondary waste to biochars and evaluated their potential application in water purification by removing lead (Pb) from contaminated water. Based on the results, the produced biochar showed a high Pb adsorption ability (134 mg/g), with 66.5% of lead removal achieved within the first 30 min. Experimental and modeling results indicated that both physisorption and chemisorption mechanisms were involved in the Pb adsorption of the biochar. Finally, techno-economic analysis was conducted to evaluate the economic feasibility of the integrated processing of GP into oil, polyphenols, and biochar at an industrial scale. The results showed that compared with generating of single product or dual products, the integrated process aiming to produce multiple products had the best economic performance with the net present value (NPV), internal rate of return (IRR), and payback period of $135.0 million, 47.5%, and 1.8 years, respectively. Sensitivity analysis showed that plant capacity and polyphenol selling price had major impacts on process economics. Therefore, a suggestion for implementing this integrated process is to invest more in the polyphenol production and purification process to generate high-quality polyphenols with a high selling price and running the plant with a large capacity. Overall, we explored a novel integrated process that aims to produce multiple value-added products to increase the economic gain for the wine industry, and at the same time, potentially reduce the environmental burdens caused by GP disposal. / Doctor of Philosophy / During wine making, a large amount of solid waste is generated, and the major one is called grape pomace (GP). GP is mainly consisted of grape skins, seeds, and some stems. Normally, GP is discarded as waste; however, if it is not handled properly, GP may cause serious damages to the environment such as contaminating soil and stream water. On the other hand, GP has valuable compounds that could be recovered for other applications. Previous researchers used GP to produce a single product, which still leads to a large amount of components not used. Therefore, the aim of the current study is to design a process to comprehensively utilize GP to produce multiple value-added products. The developed process can produce grape seed oil, polyphenols, and biofuels from GP. The solid residue generated from the designed process was further converted into biochar, which can be used as an excellent adsorbent to remove lead (Pb) from contaminated water. Based on the economic model results, the developed process to convert GP into grape seed oil, polyphenols, and biochar could be a promising investment at an industrial scale. Generally speaking, various valuable products were obtained from low value GP waste, which could not only reduce the potential environmental problems caused by waste disposal, but also provide different value-added products for food, pharmacy, chemical, and energy industries.

Graphite materials are vital industrial products. The rapid development of the battery and electronic computer industries has incentivized a great demand for graphite materials. However, today, graphite materials are commercially produced via thermal treating fossil oil or coal derived coke at a temperature higher than 2500℃. Both of the fossil-based feedstock and the energy-intensive production process are contrary to the concept of sustainable development. This thesis proposes a sustainable low-temperature catalytic graphitization process to produce graphite materials with highly ordered crystallinity by using commercial biomass pyrolysis biochar as the feedstock. Iron nitrate was selected as the graphitization catalyst. The effect of the graphitization temperature and the iron loading amount on the properties of the produced carbon products was studied. Produced graphite materials were characterized by performing X-ray diffraction, Nitrogen adsorption-desorption, and elemental analysis. Results show that the average graphitic crystalline size and the degree of graphitization of the product increased with the increase of the graphitization temperature and the iron loading amount. However, the increase of the iron loading amount reduced the catalyst removal efficiency of the acid washing process. When the graphitization temperature is higher than 1100℃ and the iron loading amount is higher than 11.2 wt.%, the crystallinity of the produced graphite material is better than that of the commercial graphite. The graphite material with the best crystallinity, which was produced at a temperature of 1300℃ and an iron loading of 33.6 wt.%, has crystallinity very close tothe pure graphite. / Grafitmaterial är viktiga industriprodukter. Den snabba utvecklingen av batteri- och elektronikdatorindustrin har stimulerat en stor efterfrågan på grafitmaterial. Idag framställs emellertid grafitmaterial kommersiellt via termisk behandling av fossil olja eller kol härledd koks vid en temperatur högre än 2500℃. Både det fossilbaserade råvaran och den energikrävande produktionsprocessen strider mot begreppet hållbar utveckling. Denna avhandling föreslår en hållbar katalytisk grafitiseringsprocess vid låg temperatur för att producera grafitmaterial med högt ordnad kristallinitet genom att använda kommersiell biomassapyrolysbiokol som råmaterial. Järnnitrat valdes som grafitiseringskatalysator. Effekten av grafitiseringstemperaturen och järnbelastningsmängden på egenskaperna hos de producerade kolprodukterna studerades. Framställda grafitmaterial kännetecknades av utförande av röntgendiffraktion, kväve-adsorptionsdesorption och elementaranalys. Resultaten visar att den genomsnittliga grafitiska kristallina storleken och graden av grafitisering av produkten ökade med ökningen av grafitiseringstemperaturen och järnbelastningsmängden. Ökningen av järnbelastningsmängden minskade emellertid katalysatorns avlägsnande effektivitet för syratvättprocessen. När grafitiseringstemperaturen är högre än 1100℃ och järnbelastningsmängden är högre än 11,2 viktprocent, är kristalliniteten hos det producerade grafitmaterialet bättre än den för den kommersiella grafiten. Grafitmaterialet med den bästa kristalliniteten, som producerades vid en temperatur av 1300℃ och en järnbelastning på 33,6 viktprocent, har kristallinitet mycket nära den rena grafiten.

Rice is a staple crop for many countries around the world, and is one of the top three food sources globally. Many environments where rice is grown contain stressors likely to limit its growth and yield. In southern Senegal (Casamance region), rice is mainly cultivated in lowlands near estuaries where drought, salinity, acidity, poor soil fertility, and iron toxicity are the main limiting factors. In Casamance, average rice yield for local farmers is 1 to 2 tons per hectare (809 to 1618 pounds per acre), compared to worldwide average yield of more than 4 tons per hectare. The soil where our 2-year experiment (2014 and 2015) was conducted is highly saline-sodic and acidic, and the salt tolerant cultivar we grew yielded 3.4 tons per hectare in 2013. Our main objective was to increase rice yield. The water table height, salinity, and pH were measured weekly during the rice growing season, and the soil was described, sampled, and analyzed to better understand the water and soil resources. Two planting methods were tested: flat planting and planting on beds. Two soil amendments were compared with each planting method: biochar and crushed oyster shells, alone and in combination. An untreated control was included in the experiment. All plots were fertilized. Treatment effects on soil properties and yield were compared in a split-plot design. Plant tissue was sampled for elemental content. The water table was above the surface and was saline during half of the growing season in 2014, and decreased after rice grain head emerged. Planting methods and amendments did not have an effect on yield in 2014, but biochar amendment increased yield in 2015. In 2014, soil salinity and sodium decreased to below toxic levels late in the growing season in the flat plots but not in the bedded plots. Therefore, flat planting is more appropriate in these lowland rice production systems. Soil pH increased from 4.4 to 7.7 in flat planting where biochar+shell was applied. Soil available nutrients such as P, Mn, and Zn were significantly higher in flat planting compared to beds. Toxic levels of Na (> 2000 milligrams per kilogram) were measured in leaves sampled just before flowering. We recommend flat planting and amending soil with biochar in saline-sodic acid-sulfate paddy soils in Casamance to improve rice yield. / Master of Science

Direct carbon fuel cell (DCFC) is a high temperature fuel cell (around 700 "C) that produces electrical energy from the direct conversion of the chemical energy of carbon. DCFC has a higher achievable efficiency of 80% compared to other fuel cells and the corresponding CO2 emission is very low compared to conventional coal-burning power plants. Moreover, a DCFC can use diversified fuel resources even waste material, which is advantageous compared to other types of fuel cells which are limited to specific fuels. DCFCs are still under development due to a number of fundamental and technological challenges such as the efficiency of carbon fuels and the effect of impurities on the performance and lifetime of the DCFC. These are key factors for the development and commercialization of these devices. In this study, three biochars obtained from the pyrolysis of poultry litters (PL) collected from Tunisian and US farmers, were characterized to see whether they can be potential anode fuels for DCFC or not. PL biochars have low fixed carbon contents (19-35 wt%) and high ash contents (32.5-63 wt%). These ashes contain around 40 wt% catalytic oxides for carbon oxidation reaction, however, these oxides have very low electrical conductivities, which resulted in the very low (negligible) electrical conductivity of the PL biochars (7.7x10-9-70.56x10-9 S/cm) at room temperature. Moreover, the high ash contents resulted in low surface areas (3.34-4.2 m"/g). These findings disqualified PL biochar from being a potential anode fuel for DCFCs. Chemical demineralization in the sequence HF/HCl followed by carbonization at 950" C of the PL biochars will result in higher fixed carbon content, higher surface area, and higher electrical conductivities. Moreover, the treated PL biochars would contain a potential catalyst (Calcium in the form of CaF2) for carbon oxidation. All these criteria would qualify the treated PL biochars to be potential fuels for DCFC. / Master of Science

Casamance is a region in southern Senegal that traditionally produces rainfed rice, but Senegal produces only 1/3 of its rice consumption. Lowland areas, where rice is primarily produced, have acid sulfate soils with low pH and potential aluminum and iron toxicity. The goal of this work was to determine if soil amendments can alleviate soil acidity, counteract the negative biogeochemical effects that occur in flooded conditions, and increase rice yield. A two-year experiment was conducted to test the following soil treatments – agricultural lime, pulverized oyster shell, biochar, and control (no amendment) – in flat and raised beds. Plots amended with lime and shell materials had increased soil pH, base saturation, Ca, and cation exchange capacity. Meanwhile, biochar elevated particulate organic matter and C:N ratios. Exchangeable Fe and Al were negatively correlated with soil pH, while Geobacteraceae populations (Fe reducing bacteria) increased with pH. A greater proportion of the total Fe was strongly bound in fractions that were less bioavailable in plots amended with shell or lime, and overall rice yields were significantly higher following amendment with shell or lime. During the second growing year these effects diminished, suggesting that liming effects did not persist as expected. These results demonstrate the benefits of soil amendments that raise soil pH and suggest that this effect operates by influencing overall soil nutrient availability to rice plants, but further research is needed regarding the timing and sustainability of the beneficial liming effect. / Master of Science

The global nitrogen cycle has been disrupted by large anthropogenic inputs of reactive nitrogen to the environment. Excess nitrogen underlies environmental problems such as eutrophication, and can negatively affect human health. Managing the natural microbial process of denitrification is advocated as a promising avenue to reduce excess nitrogen, and denitrifying bioreactors (DNBRs) are an emerging technology harnessing this biochemical process. Previous DNBR research has established successful nitrate removal, whereas this study examines the potential to expand DNBR functionality to address excess phosphorus and mitigate the production of nitrous oxide, a potent greenhouse gas. Results from a laboratory experiment supported the hypothesis that the addition of biochar, a charcoal-like soil amendment and novel organic carbon source in DNBR research, would increase nitrate and phosphorus removal as well as decrease the accumulation of nitrous oxide, an intermediate product of microbial denitrification. In order more closely examine the ratio of the products nitrous oxide and inert dinitrogen, development of a novel analytical method to quantify dissolved gases in environmental water samples using gas chromatography mass spectrometry was undertaken. Although static headspace analysis is a common technique for quantifying dissolved volatiles, the variation in sample preparation has recently been revealed to affect the determination of dissolved concentrations of permanent gases and convolute comparison between studies. This work demonstrates the viability of internal calibration with gaseous standard addition to make dissolved gas analysis more robust to variable sample processing and to correct for matrix effects on gas partitioning that may occur in environmental samples. / Master of Science

Denna studie undersökte vilka tänkbara effekter applicering av biokol i boreal skogsmark kan ge och vart den största nyttan kan finnas. Studien uppfördes som litteraturstudie och sammanställde relevant forskningsresultat som behandlar biokol i boreal skogsmark. Resultatet visar ökningar i tillväxt hos tall på magrare marker med grövre textur. En ökning av pH-värde noterades vilket generellt ökar markens katjonbyteskapacitet och höjer tillgången på tillgänglig näring. Försurning av skogsmark kan minskas genom biokolets pH-höjande egenskaper. Markens vattenegenskaper påverkades genom en ökning av markfuktighet och kan minska riskerna för skador orsakade av abiotiska och biotiska skadegörare. Utflödet av koldioxid från marken ökade marginellt i förhållande till mängden tillfört kol genom biokolets kolhalt samt markens bundna kollager. Genom framtida kolkreditsystem med applicering av biokol i skogsmark öppnar det upp möjligheter till andra ekonomiska inkomstkällor för skogsägaren än det traditionella virkesvärdet.

Soil organic matter (SOM) is a critical biogeochemical pool that can be managed as part of global efforts to conserve nutrients and enhance carbon (C) sequestration. But reliably increasing SOM has proven difficult because most of the organic matter that enters soil as plant litter and organic amendments (i.e., compost, manure) is susceptible to decomposition by soil microorganisms and eventually is lost to the environment as greenhouse gases and non-point source pollution. Many soils lack the physical and/or chemical properties that enable some human-modified soils (e.g., terra preta soils in the Amazon Basin) to stabilize and retain C and nutrients in SOM while maintaining relatively high levels of productivity compared to surrounding natural soils that formed under similar conditions. I hypothesized that two of the major stabilizers of organic matter common to terra preta soils of the Amazon basin – black carbon (biochar) and poorly crystalline, reactive iron (Fe) minerals – could be applied to a fine-textured soil from Southwest Virginia to improve the accumulation and retention of C and nitrogen (N). I used a field experiment to compare the effects of three types of locally-produced biochars applied with and without an organic N fertilizer (blood meal) on soil C and N availability. I then used an incubation experiment featuring the soils from the aforementioned field experiment to examine the effects of applying Fe2+ -treated manure effluent on the retention of C and N in unamended and hardwood biochar-amended soils. I found that biochar adsorbed inorganic N in all cases, while providing a reliable, stable increase in SOM due to its recalcitrant nature. However, the manure effluent used in the incubation experiment stimulated the decomposition of mineral-associated organic matter (MAOM), with the addition of Fe2+ to the manure mitigating this apparent positive priming effect and the presence of biochar actually reversing this effect and promoting an increase in MAOM following manure application to biochar-amended soil. Overall, biochar stimulated the retention of N by decreasing the leachable inorganic N in the soil and enhanced soil C stocks. Additionally, biochar applications had the added benefit of promoting the accumulation of manure in soil as stable, microbially-processed MAOM, while co-applying Fe2+ with manure only served to inhibit the priming of native soil C. / Master of Science / Organic matter is an important constituent of all soils. Farmers and gardeners would like to increase the organic matter on their lands to improve their crop yields and health of their soils, yet people in many regions of the world struggle with actually getting long-lasting forms of organic matter to accumulate in soils. Moreover, managing soils to increase the amount of carbon stored in these long-lasting forms has the benefit of offsetting human contributions to atmospheric carbon dioxide and global warming. Some soils stabilize and build up organic matter more efficiently than others, and I hypothesized that if two well-known soil materials that help to stabilize organic matter – charcoal and iron – were added to a soil, then the accumulation of organic matter in the soil could be improved. The first part of my research was a field experiment in which three different kinds of charcoal were added either with or without an organic fertilizer to the soil in a Southwest Virginia pasture. I then measured the amount of carbon in the soil and determined that charcoal additions increased soil carbon and helped to retain mobile forms of plant nutrients. The second part of my research used the charcoal-treated and untreated soils from the field experiment for a project where cow manure was co-applied with three levels of iron and added to soils in jars in a controlled laboratory setting. The jars were then maintained at an ideal moisture and temperature for the growth of microbes for 70 days and analyzed afterwards. I found that the manure caused the organic matter in the soil to be consumed by microbes, while charcoal caused the organic matter from the manure to accumulate and remain. Adding iron with the manure prevented the microbes from consuming the pre-existing organic matter in the soil, but did not contribute to the retention of the manure in the soil. Overall, while both iron and charcoal influenced the retention of organic matter in soil, biochar proved to be more effective at stabilizing manure organic matter than the iron additions.

The advent of industrial, fertilizer-intensive agriculture during the 20th century has promoted export of anthropogenic nutrients, spurring degradation of ecosystem biodiversity and water quality. Exported nitrogen and phosphorus are recognized drivers of this deterioration, and require management. In the mid-1990s, denitrifying bioreactors (DNBRs), a subsurface, edge-of-field best management practice (BMP) that intercepts and treats agricultural drainage by supporting nitrate-attenuating denitrification with a saturated, carbon-filled substrate, were developed. Since then, their utility has expanded, and recent studies have unearthed biochar's capability to stimulate simultaneous nitrate (NO3--N) and phosphate (PO43--P) removal in DNBRs. This study investigated biochar's potential as an amendment to the traditional woodchip media by conducting nine, five-day trials on twelve laboratory-scale, horizontal flow-through DNBR columns. Three media types were tested: woodchips (W), 90% woodchips and 10% biochar (B10), and 70% woodchips and 30% biochar (B30). Simulated agricultural drainage with four unique concentration combinations of 16.1 and 4.5 mg L-1 NO3--N and 1.9 and 0.6 mg L-1 PO43--P was delivered at hydraulic retention times (HRTs) of 3, 6, and 12 h. Mean NO3--N removal efficiencies ranged from 16.9%-93.7%, and media type was insignificant at low influent NO3--N concentrations, but B30 was the most effective at high influent NO3--N concentrations. Mean PO43--P removal efficiencies ranged from -122.0%-74.9%, with B10 and B30 significantly worse than W at removing PO43--P. These findings corroborate previous work indicating boosted NO3--N removal with biochar, but contradict studies upholding PO43--P-removing capabilities. / Master of Science / Nitrogen and phosphorus-containing nutrients are applied to agricultural fields for supporting higher crop yields, and once these nutrients are exported they can negatively impact ecosystem biodiversity and water quality. These nutrients therefore require management. Denitrifying bioreactors (DNBRs) are subsurface engineered structures that intercept and treat agricultural drainage by supporting nitrate-removing denitrification with a carbon substrate. Recent studies have unearthed the potential of biochar, which is a type of charcoal typically used for soil amendment, as a substrate for promoting simultaneous removal of nitrogen and phosphorus. This study investigated biochar’s potential as an amendment to the traditional DNBR woodchip media using laboratory-scale DNBRs that were subjected to different hydraulic retention times and influent nutrient concentrations. Results revealed that the biochar did not significantly enhance nitrate removal under low influent nitrate concentrations, but did significantly improve nitrate removal at high influent nitrate concentrations. The biochar-amended treatments were significantly worse than the woodchip treatments at supporting phosphate removal. These findings suggest that biochar may indeed boost nitrate removal, but may not improve phosphate removal.