Contamination of groundwater supplies by gasoline and other petroleum-derived hydrocarbons released from underground or aboveground storage tanks is a serious and widespread environmental problem. Corrosion, ground movement, and poor sealing can cause leaks in tanks and associated piping. Petroleum hydrocarbons contain methyl tertiary-butyl ether (MTBE) (a fuel oxygenate), benzene, toluene, ethylbenzene, and xylene isomers (BTEX), the major components of gasoline, which are hazardous substances regulated by many nations. MTBE possesses all the characteristics of a persistent compound in the subsurface: high solubility, low volatility, low sediment sorption, and resistance to biodegradation. The objectives of this study were to (1) evaluate the biodegradibility of MTBE under aerobic conditions, and (2) assess the potential of using the aerobic bioremediation technique to clean up aquifers contaminated by MTBE. In this study, microcosms were constructed to determine the feasibility of biodegrading MTBE by intrinsic microbial consortia (aquifer sediments) under aerobic and aerobic cometabolic conditions. In the cometabolic microcosms, propane, ethanol, and BTEX were applied as the primary substracts to enhance the biodegradation of MTBE. The inocula used in this microcosm study were aquifer sediments collected from the contaminated-zones of a petroleum-hydrocarbon (including MTBE) contaminated site. Microcosms were constructed with nutrient medium (or site groundwater), sediments, and MTBE solution in 70-mL serum bottles sealed with Teflon-lined rubber septa. MTBE was analyzed using purge-and-trap instrument following gas chromatography (GC)/flame ionization detector (FID). Results show that the indigenous microorganisms were able to biodegrade MTBE under aerobic conditions using MTBE as the sole primary substrate. Microcosms with site groundwater as the medium solution show higher MTBE biodegradation rate. This indicates that site groundwater might contain some trace minerals or organics, which could enhance the MTBE biodegradation rate. Results show that the addition of BTEX would also enhance the MTBE removal. However, no significant MTBE biodegradation was observed in microcosms with propane and ethanol as the primary substrates. This reveals that the supplement of the second carbon source might inhibit the degradation of MTBE due to the preferential removal of some organics over MTBE. Results from the microcosm study suggest that aerobic biodegradation plays an important role on the MTBE removal. Intrinsic bioremediation is a feasible technology to remediate the studied MTBE-contaminated site.

Arsenic is a toxic element that is widely distributed throughout the earth??s crust as a result of both natural geologic processes and anthropogenic activities. In virtually all environments, methylated forms of arsenic can be found. Because of the widespread distribution and toxicity of arsenic and methyl-arsenic, their adsorption behavior on soil minerals is of great interest. Although considerable attention has been given to the behavior of inorganic arsenic on mineral surfaces, little research has been conducted regarding interactions of the methyl-arsenic forms. The objective of this study was to compare the adsorption and desorption behavior of methylarsonate (MMAsV), methylarsonous acid (MMAsIII), dimethylarsinate (DMAsV), dimethylarsinous acid (DMAsIII), arsenate (iAsV), and arsenite (iAsIII) on iron oxide minerals (goethite and ferrihydrite) by means of adsorption isotherms and adsorption envelopes. Additionally, desorption envelopes were obtained using sulfate and phosphate as competitive ligands. Arsenic was measured by FI-HG-AAS. MMAsV and iAsV were adsorbed in higher amounts than DMAsV on goethite and ferrihydrite at all pH values studied. Although MMAsV and iAsV were adsorbed quantitatively at lower concentrations on goethite and ferrihydrite, as arsenic concentration was increased MMAsV was adsorbed in slightly lower quantities than iAsV. DMAsV was not quantitatively adsorbed at any concentration on goethite or ferrihydrite. MMAsV and iAsV exhibited high adsorption affinities on both goethite and ferrihydrite at pH values below 9 and showed decreasing adsorption above this point (more rapidly for MMAsV). DMAsV was adsorbed only at pH values below 8 on ferrihydrite and below 7 on goethite. MMAsV, iAsV, and DMAsV each exhibited adsorption characteristics suggesting specific adsorption on both goethite and ferrihydrite. Increased methyl substitution resulted in increased ease of arsenic release from the iron oxide surface. MMAsIII and DMAsIII exhibited no evidence for any type of specific adsorption under the conditions studied. Phosphate was a more effective desorbing ion than sulfate, but neither desorbed all arsenic species quantitatively.

Abstract Methyl Viologen is a kind of organic molecular magnet of current interest which comprises with organic radicals (unpaired electrons). The molecular formula of the sample is (C12H14N2)2+X2-, where ¡§X2-¡¨ denotes a non-magnetic anion (CdI42-, I3-I- etc.). We perform the magnetization (using SQUID magnetometer) and electron paramagnetic resonance (EPR) measurements. Two absorption peaks are observed in EPR spectrum indicating that there are two radical forms in our samples. One of the radicals exists in every sample having the g1-factor value 2.004. The other radical which has the g2-factor 2.001 exists only in certain samples. Interestingly, we find that these samples exhibit ferromagnetism at room temperature. We use Lorentzian profile to quantitatively analyze the EPR spectrum of the samples and derive the ratio (A2/A1) of two different absorption peaks, which represents the amount of g2 radical. The remanent magnetization and saturation magnetization are found to increase as the ratio value increases, indicating that the strength of ferromagnetism is strongly correlated with g2 radical.

£¸¡B Pyrolysis of 2-methoxy-2¡¦-methylthiostilbene (22a) and 2,2¡¦-di(methylthio)stilbene (22b) gave not only polycyclic aromatic hydrocarbons (PAH) 17¡B18¡B2, but also the products 33, 34. In addition, photolysis of 22a¡B22b¡B2,2¡¦-dimethoxy stilbene (13) gave photocyclic products 31¡B40¡B12¡B45¡B46. ¤G¡B Pyrolysis of 2-dimethylamino-N-(arenylidene)anilines (20a-f) gave not only 1-methyl-2-arylbenzimidazole (25a-f), but also gave 2-arylquinoxaline (26a-e). Furthermore, compound 20f gave 37 and 25f, but didn't give 26f. ¤T¡B Pyrolysis of benzoic 1,2-dimethyl-3-indolyl anhydride gave 1,2-dimethylindole (19) ¡B3-methylquinoline (30) ¡B4-methylquinoline (31).

Contamination of soil/groundwater supplies by gasoline and other petroleum-derived hydrocarbons released from underground storage tanks (USTs) is a serious and widespread environmental problem. Corrosion, ground movement, and poor sealing can cause leaks in tanks and associated piping. Petroleum hydrocarbons contain methyl tertiary-butyl ether (MTBE) (a fuel oxygenate), benzene, toluene, ethylbenzene, and xylene isomers (BTEX), the major components of gasoline, which are hazardous substances regulated by many nations.The objective of this proposed study is to assess the potential of using a passive in situ oxidation barrier system. This passive active barrier system has advantages over conventional systems including less maintenance, cost-effectiveness, no above-ground facilities, no groundwater pumping and reinjection, and groundwater remediation in situ. The oxidation barrier system included a persulfate-releasing barrier, which contains persulfate-releasing materials. The slow-released persulfate would oxidize MTBE and benzene in aquifer. The persulfate-releasing materials would release persulfate when contacts with groundwater, thus oxidizes the MTBE and benzene. In the first part of this study, bench scale experiment was also performed to produce the persulfate-releasing materials high persulfate-releasing rate. The components of the persulfate-releasing materials and optimal concentrations of those components were determined in this study. Results indicate that the highest persulfate releasing rate can be obtained when the mass ratio of cement/sand/water was 1.4/0/0.7. Result obtained from the persulfate-releasing materials test and bench-scale were used for the design and operation of the following column experiments. Results from the column experiment indicate that approximately 98% of MTBE and 99% of benzene could be removed during the early persulfate-releasing stage. Results also reveal that the produced oxidation byproducts of MTBE, tert-butyl formate (TBF) and tert-butyl alcohol (TBA), can also be produce an acetone. Results from this study suggest that extra Fe(II) would cause the decrease in oxidation rates due to the reaction of sulfate with Fe(II). Results show that the parameters, which would affect the oxidation rate include persulfate concentration, oxidant reduction potential (ORP), conductivity, sulfate concentration, and contaminant concentration. The proposed treatment scheme would be expected to provide a more cost-effective alternative to remediate MTBE and other petroleum-hydrocarbon contaminated aquifers. Knowledge obtained from this study will aid in designing a persulfate oxidation system for site remediation.

No description available.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1969. / Includes bibliographical references (p. 106-109).

Wood products all require treatment to mitigate phytosanitary risk prior to exportation. The most common phytosanitary treatment applied to Pinus radiata logs is Methyl Bromide (MeBr). The Environmental Protection Agency (EPA) in 2010 stated that MeBr must not be release into the atmosphere past 2020. This poses a problem for New Zealand log exports. Radiation has been identified as a possible alternative phytosanitary treatment for export wood products. This study aimed to quantify the effective dose of radiation necessary to sterilise two forest pest species; Arhopalus ferus and Hylurgus ligniperda. These species are representative of two different types of forestry pests; bark beetles (H. ligniperda) and wood borers (A. ferus). All applicable life stages for both species were tested. Arhopalus ferus adults were the most susceptible life stage identified with an LD99 of 30.2Gy ± 13.5 Gy (95% confidence interval). Arhopalus ferus eggs were less susceptible with a LD99 of 750Gy ± 776Gy observed; however there is low confidence in this result due to a methodological issue in one treatment replicate. Hylurgus ligniperda eggs were observed to be less susceptible than A. ferus eggs with a LD99 of 289Gy ± 92Gy. Results for the other life stages were inconclusive due to poor control survival, however the information gained was used to develop improved methods for further experimentation, which is on-going and showing positive results so far. The results of this experiment have indicated that radiation can be an effective method of sterilising forestry pests. To date radiation has not been used as phytosanitary risk mitigation for wood exports; however it is widely used for risk mitigation in agricultural products. Currently there remains a large amount of unknown information regarding, the effectiveness for irradiation of logs, the effective dose require for sterilisation of the most tolerant forestry pest and public acceptability of irradiation as a phytosanitary treatment. These knowledge gaps and an economic assessment must be completed before irradiation can be used as a phytosanitary risk mitigation technique for forestry products.

Titanium Dioxide (TiO 2) has been considered an ideal photocatalyst due to factors such as its photocatalytic properties, chemical stability, impact on the environment and cost. However, its application has been primarily limited to ultraviolet (UV) environments due to its high band gap (3.2 eV). This high band gap limits the harvesting of photons to approximately 4% of sunlight radiation. Research today is focused on lowering this gap by doping or coupling TiO 2 with other semiconductors, transition metals and non-metal anions, thereby expanding its effectiveness well into the visible range. This thesis explores the effects of thermal and thermochemical ammonia treatment of nano-particulated TiO 2. The objective is to synthesize a photocatalytic activity in the visible range while at the same time retaining its photocatalytic properties in the UV range. Specifically, this study utilizes pure commercial nano-particulated TiO 2 powder (Degussa P-25), and uses this untreated TiO2 as a baseline to investigate the effects of thermal and thermochemical treatments. Nitrogen-doping is carried out by gas phase impregnation using anhydrous ammonia as the nitrogen source and a tube furnace reactor. The effects of temperature, time duration and gas flow rate on the effectiveness of thermally and thermochemically treated TiO 2 are examined. Thermally treated TiO 2 was calcinated in a dry inert nitrogen (N2) atmosphere and the effects of temperature and treatment duration are investigated. The band gap of the thermally treated and thermochemically ammonia treated TiO 2 have been measured and calculated using an optical spectrometer. The photocatalytic properties of all materials have been investigated by the degradation of methyl orange (MO) in an aqueous solution using both visible simulated solar spectrum (VSSS) and simulated solar spectrum (SSS) halogen light sources. Methyl orange degradation has been measured and calculated using an optical spectrometer. The phase structure and particle size of the materials is determined using x-ray diffraction (XRD). The BET surface area of the samples has been obtained using an Autosorb. Surface or microstructure characterization has also been obtained by scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

Cellulose is one of the most abundant biopolymers found in nature. Cellulose based derivatives have a number of advantages including recyclability, reproducibility, biocompatibility, biodegradability, cost effectiveness and availability in a wide variety of forms. Due to the benefits of cellulose based systems, this research study was aimed at developing novel cellulosic nanoparticles with potential pharmaceutical and personal care applications. Two different cellulosic systems were evaluated, each with its own benefits and proposed applications. The first project involves the synthesis and characterization of polyampholyte nanoparticles composed of chitosan and carboxymethyl cellulose (CMC), a cellulosic ether. EDC carbodiimide chemistry and inverse microemulsion technique was used to produce crosslinked nanoparticles. Chitosan and carboxymethyl cellulose provide amine and carboxylic acid functionality to the nanoparticles thereby making them pH responsive. Chitosan and carboxymethyl cellulose also make the nanoparticles biodegradable and biocompatible, making them suitable candidates for pharmaceutical applications. The synthesis was then extended to chitosan and modified methyl cellulose microgel system. The prime reason for using methyl cellulose was to introduce thermo-responsive characteristics to the microgel system. Methyl cellulose was modified by carboxymethylation to introduce carboxylic acid functionality, and the chitosan-modified methyl cellulose microgel system was found to be pH as well as temperature responsive. Several techniques were used to characterize the two microgel systems, for e.g. potentiometric and conductometric titrations, dynamic light scattering and zeta potential measurements. FTIR along with potentiometric and conductometric titration was used to confirm the carboxymethylation of methyl cellulose. For both systems, polyampholytic behaviour was observed in a pH range of 4-9. The microgels showed swelling at low and high pH values and deswelling at isoelectric point (IEP). Zeta potential values confirmed the presence of positive charges on the microgel at low pH, negative charges at high pH and neutral charge at the IEP. For chitosan-modified methyl cellulose microgel system, temperature dependent behaviour was observed with dynamic light scattering. The second research project involved the study of binding interaction between nanocrystalline cellulose (NCC) and an oppositely charged surfactant tetradecyl trimethyl ammonium bromide (TTAB). NCC is a crystalline form of cellulose obtained from natural sources like wood, cotton or animal sources. These rodlike nanocrystals prepared by acid hydrolysis of native cellulose possess negatively charged surface. The interaction between negatively charged NCC and cationic TTAB surfactant was examined and it was observed that in the presence of TTAB, aqueous suspensions of NCC became unstable and phase separated. A study of this kind is imperative since NCC suspensions are proposed to be used in personal care applications (such as shampoos and conditioners) which also consist of surfactant formulations. Therefore, NCC suspensions would not be useful for applications that employ an oppositely charged surfactant. In order to prevent destabilization, poly (ethylene glycol) methacrylate (PEGMA) chains were grafted on the NCC surface to prevent the phase separation in presence of a cationic surfactant. Grafting was carried out using the free radical approach. The NCC-TTAB polymer surfactant interactions were studied via isothermal titration calorimetry (ITC), surface tensiometry, conductivity measurements, phase separation and zeta potential measurements. The major forces involve in these systems are electrostatic and hydrophobic interactions. ITC and surface tension results confirmed two kinds of interactions: (i) electrostatically driven NCC-TTAB complexes formed in the bulk and at the interface and (ii) hydrophobically driven TTAB micellization on the NCC rods. Conductivity and surface tension results confirmed that the critical micelle concentration of TTAB (CMCTTAB) shifted to higher values in the presence of NCC. Phase separation measurements allowed us to identify the formation of large aggregates or hydrophobic flocs depending on the TTAB concentration. Formation of NCC-TTAB complexes in aqueous solutions was confirmed by a charge reversal from negative to positive charge on the NCC rods. The effect of electrolyte in shielding the negative charges on the NCC was observed from ITC, surface tensiometry and phase separation experiments. Several mechanisms have been proposed to explain the above results. Grafting of PEGMA on the NCC surface was confirmed using FTIR and ITC experiments. In phase separation experiments NCC-g-PEGMA samples showed greater stability in the presence of TTAB compared to unmodified NCC. By comparing ITC and phase separation results, an optimum grafting ratio (PEGMA : NCC) for steric stabilization was also proposed.