Increasing volumes of Chromated Copper Arsenate (CCA) treated wood materials are being removed from service, either as a result of reaching the end of their service life or being replaced with non-treated wood materials. These materials, while not regulated as hazardous wastes, have the potential to leach toxic metals into the environment. Incineration and landfilling are not ideal disposal methods as incineration could result in the volatilization of carcinogenic arsenic and chromium, while landfilling requires the waste to be sorted and placed in appropriately lined landfills to prevent contaminant release. Viable disposal methods must be considered to manage the significant waste stream of CCA-treated wood. This study investigates pyrolysis and electrokinetics (EK) as possible remediation techniques for the treatment of CCA-treated wood waste. A unique bench pyrolysis reactor was designed and optimized over three pyrolysis temperatures for retention of CCA metals within the char and bio-oil pyrolysis products. A batch pyrolysis system was constructed to produce large quantities of pyrolysis char for use in EK experiments. Mass balances were performed across both bench and batch pyrolysis systems, with metal distribution trends ascertained. EK experiments were performed on the char generated during batch pyrolysis as well as CCA-treated wood waste to evaluate the efficiency of coupling the two technologies. These EK studies were performed using pH regulation at the cathode and applying constant current. Distribution of the CCA metals post-EK experiment was determined and removal efficiencies were calculated. The mobility of the CCA metals was evaluated during all phases of this investigation using Toxicity Characteristic Leaching Procedure (TCLP), Synthetic Precipitation Leaching Procedure (SPLP), and Deionized Water Leaches to determine the likelihood of metal leaching under different environmental conditions.

No / A microemulsion electrokinetic chromatography (MEEKC) method has been developed and validated for the determination of 4-hydroxybenzoates and their impurities. These materials are commonly known as parabens and are widely used as preservatives in foods, cosmetics and pharmaceuticals. The method was shown to be selective and quantitative for the methyl, ethyl, propyl and butyl esters of 4-hydroxybenzoic acid. An internal standard, 4-hydroxyacetophenone, was employed to improve injection precision and detector linearity. In addition, 4-hydroxybenzoic acid, the major degradent, could also be monitored at the 0.1% (m/m) level. The method was successfully validated for assay and detection of the impurities in 4-hydroxybenzoic acid methyl ester and 4-hydroxybenzoic acid propyl ester samples and for the determination of 4-hydroxybenzoic acid methyl ester in a liquid pharmaceutical formulation. The determination of paraben content by MEEKC in a liquid sample was consistent with HPLC analysis. This work is the first reported validated MEEKC method and shows that the methodology can be successfully implemented into routine quality control testing.

Cette thèse porte sur l’analyse didactique de pratiques d’enseignement de la physique au niveau de l’enseignement secondaire du second cycle en Angola. Il s’agit d’une étude de cas de deux professeurs de lycée angolais. Nous avons analysé les pratiques d’enseignement mises en œuvre par ces deux professeurs à partir de leurs activités réalisées en physique sur une séquence d’étude sur l’électrocinétique en classe de terminale. Nous avons cherché à décrire les pratiques de ces enseignants, puis après à les comprendre, donc à voir quels pourraient être certains des déterminants. Pour aborder cette étude, nous nous sommes appuyés sur la théorie de l’action conjointe en didactique (T.A.C.D), fondée sur la notion de jeu didactique et d’action conjointe liée à des transactions à propos du savoir en jeu. En effet, selon cette théorie, Sensevy (2007) considère ce qui se passe dans une classe comme une succession de jeux. Il précise à cet effet que « un jeu a un enjeu, ce qui fait qu’on se prend au jeu, on y gagne ou on perd ; il faut, pour gagner, produire des stratégies gagnantes et donc avoir le sens du jeu ».Au terme de notre étude, nous avons observé qu’il s’agit d’un cas particulier d’action conjointe dans laquelle le professeur porte la majeure partie des responsabilités, où certains concepts de la TACD de ce fait perdent de leur pertinence. En même temps, c’est aussi cette perte de pertinence, cet usage à minima, la redondance de certains concepts (mesogenèse et chronogenèse) qui permet aussi de caractériser les pratiques analysées. Dans ce cas, même si les potentialités ne sont pas totalement utilisées, les descripteurs de la TACD permettent quand même de rendre compte de ce qui se passe en classe. / This thesis talks about the didactic practical analysis of the teaching of physical in the second cycle of secondary education in Angola. It is a case study of two Angolan high school teachers. We have analyzed teaching practical used by this both teachers from their activities realized in physical on a sequence study of Electrokinetic in Terminal class. We have searched to describe these teachers’ practicals. Then, after to understand then, though, see what could be some determinatives. To reach this study, we have relied ourselves on the Joint action theory of in didactic (JATD), which consist on the notion of didactic game and joint action tied to the transaction about the knowledge of the game. In fact, according to the theory (Sensevy, 2007), considers what happens in a classroom as a succession of games. He specifies at that fact that “a game has a stake that is what makes one feels themselves in a game. One can win or lose. One must produce wining strategies so they can win and thong, have a sense of game”In the limit of our study, we have observed that it is a particular case of JATD the teacher in which bears the mayor part of responsibilities, where some concepts of JATD lose in fact their relevance. In the same time, it is also this loss of relevance, this minimum use, this redundancy of some concepts (mesogenesy and chronogenesy) that permit to characterize analyzed practical. In that case, even though potentialities are not totally used, the TACD describers allow realizing what happens in class.

Electrokinetic flows within an overlapped Electrical Double Layer (EDL), which are not well-understood, were theoretically investigated in this study with the particular attention on the consideration of hydronium ions in the EDL. Theoretical models for fully-developed steady pressure-driven flow for salt-free water or a binary salt solution in a slit-like nanochannel connecting to two reservoirs were developed. The transient flow in such a domain was also simulated from static state to the final steady state. In these models, the Poisson equation and the Nernst-Planck equation were solved either by analytic methods or by the finite element method. Surface adsorption-desorption equilibrium and water equilibrium were considered to account for the proton exchange at the surface and in the fluid. These models were the first to include those comprehensive processes that are uniquely important for overlapped EDL scenarios. This study improves the understanding of electrokinetic flows within an overlapped EDL by demonstrating the profound impact of hydronium ions on the EDL structure. In the steady flow of potassium chloride solutions, hydronium ions are more enriched than potassium ions by up to 2~3 orders of magnitude, making the electrokinetic effects greatly depressed. The unequal enrichment effects of counterions were omitted in the traditional theory partially because the transient is extremely slow. The simulation results show that a concentration hump of hydronium ions initially forming at the channel entrance gradually expands over the whole channel in a way similar to the concentration plug flow moving downstream. The time required for the flow to reach the steady state could be as long as thousands of times the hydraulic retention time, dependent on the degree of the EDL overlap. This study improves the fundamental understanding for nanofluidic flows.

The objective of this research was to evaluate the treatment efficiency of a trichloroethylene(TCE)-contaminated aqueous solution and soil by combined technologies of the emulsified nanoscale zero-valent iron slurry (ENZVIS) and electrokinetic remediation process. Nanoiron was synthesized using the chemical reduction method by industrial grade chemicals. The synthesized nanoparticles contained elemental iron and iron oxide as determined by X-ray diffractmetry(XRD). Micrographs of FE-SEM have shown that a majority of nanoiron were in the size range of 30~50 nm. The stability study of food-grade soybean oil emulsion was conducted using six non-ionic surfactants and soybean oil. The results have shown that the emulsion prepared by mixed surfactants (Span 80 and Tween 40) and soybean oil yielded a better emulsion stability. Based on the above finding, the nanoiron slurry, soybean oil and aforementioned, mixed surfactants were used to prepare ENZVIS. Degradation of TCE by ENZVIS under various operating parameters was carried out in batch experiments. The experimental results have indicated that emulsified nanoiron outperformed nanoiron in TCE dechlorination rate. ENZVIS (0.75 g-Fe0/L) degradated TCE (initial conc.= 10 mg/L) down to 45 %. An increase of the oil dosage could improve the stability of the emulsion, but yielding a negative influence on degradation of TCE. Experimental results also showed that ENZVIS could remove TCE up to 94 % when pH=6. It was also formed that a higher TCE initial concentration would result in a higher TCE removal efficiency. In addition, using ENZVIS to degraded TCE-contaminated artificial groundwater has indicated that nitrate and carbonate of groundwater will suppress nanoiron reaction with TCE. Especially, a high concentration of carbonate in the reaction system might form a passive film or precipitates on nanoiron surface. This study further evaluated the treatment efficiency of combining ENZVIS and electrokinetic technology in treating a TCE-contaminated soil. Experimental conditions were given as follows:(1) initial TCE concentration in the range of 98~118 mg/kg; (2) an electric potential gradient of 1 V/cm; (3) a daily addition of 20 mL ENZVIS; and (4) a reaction time of 10 days. Experimental results have shown that an addition of ENZVIS to the anode reservoir of strongly acidic and oxidative environment would cause nanoiron to corrode rapidly and decrease TCE removal efficiency. On the other hand, an addition of ENZVIS to the cathode reservoir would enhance the degradation of TCE therein. In summary, an addition of ENZVIS to the cathod reservoir would yield the best TCE removal efficiency.

The aim of this study was to investigate the reaction behaviors of nanoscale Fe3O4 and H1/10-[Fe3O4]MgO slurry injection coupled with the electrokinectic (EK) process for remediation of NO3− and Cr6+ in saturated soil. To assure the above-mentioned nanomaterials were capable of reductively adsorbing inorganic pollutants (e.g., NO3− and Cr6+) in the acidic environment in the anode reservoir of the ek remediation system, an investigation on transformation of the concerned nanomaterials in different aqueous solutions (de-ionized water and simulated groundwater ) of different initial pHs (2 and 3.5) was conducted. Due to a high dose of nanoscale Fe3O4 and a resulting serious agglomeration while adsorbing NO3− and Cr6+, the characteristic peaks of the X-ray diffraction (XRD) analysis for nanoscale Fe3O4 remained the same after adsorption experiments. But the situations were quite different in the case of nanoscale H1/10-[Fe3O4]MgO, the characteristic peaks of £\-Fe2O3 in the XRD pattern were detected, confirming that this nanomaterial could reductively adsorb NO3− and Cr6+ in the acidic environment. The effectiveness of using polyacrylic acid (PAA) and soluble starch (SS) to stabilize nanoscale Fe3O4 and H1/10-[Fe3O4]MgO in different aqueous solutions containing humic acid was compared. It was found the former yielded a better stability. Therefore, PAA was chosen to prepare the slurries of target nanomaterials. Then slurry injection coupled with the EK process was tested for remediation of NO3- and Cr6+ in saturated soil. The results showed that the removal efficiency of NO3− was more than 90%, and the NO3− concentration in the anode reservoir was below Taiwan¡¦s Pollution Control Standards of type¢¹Groundwater for NO3−-N. Under the same test conditions, however, the removal efficiency of Cr6+ was unsatisfactory. This might be ascribed to acidification of soil near the anode resulting in high adsorption of Cr2O72− by soil. Thus, a solution to solve this problem has to seeked. The solution lies in how to enhance the contact of the above-mentioned nanomaterials with Cr6+ in the anode reservoir. One possibility is to use the nature of SS would hydrolyze in the acidic environment. Therefore, SS-stabilized nanomaterials in the acidic environment would hydrolyze resulting in the exposure of the soil nanomaterials therein. To this end, SS was used to replace PAA for nanomaterial slurry preparation for remediation of Cr6+. In addition, polarity reversal was practiced in the EK system to maintain a neutral ph of soil and increase the mobility of Cr6+ in soil. Finally, the result showed that nanoscale Fe3O4 and H1/10-[Fe3O4]MgO slurry injection coupled with the polarity reversal electrokinetic system could really enhance the removal efficiency of Cr6+ in the saturated soil. In summary, nanoscale Fe3O4 and H1/10-[Fe3O4]MgO slurry injection coupled with the EK process has been proven to be capable of remedying NO3− and Cr6+ in saturated soil. Meanwhile, the concept of reductive adsorption was realized in this work as well.

The purpose of this work was to investigate the use of nanoscale Fe3O4 as a catalytst for destruction of trichloroethylene (TCE) and 1,2-dichloroethane (1,2-DCA) by persulfate in spiked water and soil. First, nanoscale Fe3O4 was prepared by chemical coprecipitation. X-ray powder diffraction (XRD) was used to confirm the crystal structure; And size identification was performed using the scanning electron microscopy (SEM). The effectiveness of using 3 wt% soluble starch (SS) to stabilize nanoscale Fe3O4 was also studied. It was found that SS could effectively disperse the nanoparticles for more than one month. Therefore, SS was chosen to prepare the nanoscale Fe3O4 slurry. The efficiency of nanoscale Fe3O4 as an activator for persulfate remediation of TCE and 1,2-DCA in aqueous solutions (DI water, simulated groundwater, and actual groundwater) was then investigated. The results showed that all test removal efficiency of TCE and 1,2-DCA was more than 95%. Use of the persulfate for destruction of TCE and 1,2-DCA produced some by-products. The primary reaction products were cis-1,2-Dichloroethylene (cis-1,2-DCE) and trans-1,2-Dichloroethylene (trans-1,2-DCE)¡F The secondary daughter prodnct was vinyl chloride (VC). The VC produced is gradually degraded to safer substances (ethene, ethane, and methane). The nanoscale Fe3O4 slurry and the persulfate injection coupled with the electrokinetic (EK) process was tested for remediation of TCE and 1,2-DCA in saturated soil. The results showed that injection of persulfate into the EK reservoir could decrease the electrode polarization, and increase the electroosmotic flow and current density. When persulfate was injected into the cathode reservoir, the derived sulfate radicals would transfer into the soil compartment by ion migration. The injection of persulfate into the cathode reservoir was more efficient than injection of persulfate into the anode reservoir. The removal efficiency for TCE and 1,2-DCA was more than 96% in all tests. The remediation system was assessed for potential application in-situ. Soil was spiked with high TCE and 1,2-DCA and aged for a week. The injection of persulfate and nanoscale Fe3O4 slurry coupled with the EK process was tested for remediation of the aged contaminated soil. The results showed that the target contaminants (TCE and 1,2-DCA) met the Taiwan¡¦s EPA¡¦s control standard. After 30 d of remediation, the by-products (cis-1,2-DCE, trans-1,2-DCE, and VC) had also been removed to below the action limit. A cost analysis was performed in order to demonstrate the economic feasibility of the remediation method in this study. Operating costs (chemicals + electricity bill) of all tests were assessed. The results showed that the costs were 8000-17000 NT$/m3, which is economically reasonable.

A further understanding of colloidal mixture behavior under applied electric fields would greatly benefit the design of smart material systems such as electrorheological fluidic devices and microfluidic reconfigurable antennas. This thesis presents a finite element analysis of colloidal mixture electrokinetic behavior. Computations of particle forces as a function of applied frequency and particle shape were performed. An effective medium property method was also studied. Fluidic and electric forces were obtained with various applied excitation frequencies throughout three locations in a coplanar microelectrode domain. This domain consists of two 50 nanometers thick gold electrodes separated by a 30 micrometers gap. The three locations are 1.2 micrometers, 40 micrometers, and 90 micrometers from the gap center. Total force vectors were computed by integrating Maxwell and Cauchy stress tensors to determine whether the particles are pushed toward or away from the electrode gap at frequencies of 10 Hz, 1 kHz, and 100 kHz. It was determined that particles were pushed outside the gap at median frequencies of 1kHz (indicating ac electroosmotic force domination) and began to be pushed back toward the gap at higher frequencies of 100 kHz (indicating dielectrophoretic force intensification). Particle shape effects were examined by calculating the electrical interparticle force between two particles at various incidences with respect to a uniform electric field. Particle attraction occurs when the line between the particle centers is aligned with the electric field; repulsion occurs when this center line is perpendicular. The incidence angle at which the particles switch from attraction to repulsion is defined as θcr. The aspect ratio and particle edge separation distances used in this study were 1, 5,12.92 and 0.25 micrometers, 0.50 micrometers, 2.0 micrometers, respectively. The results indicate that higher aspect ratio particles tend to have smaller θcr values and larger interparticle force magnitudes for given separation distances. Finally, effective dielectric constant simulations utilizing periodic crystalline arrangements of colloidal structure were performed. The results show good agreement with the Maxwell Garnett mixing rule at volume fractions above 30 percent. Less canonical structures of cubic particles were also modeled.

Abstract A novel process of combining electrokinetic remediation and nano-sized iron wall was used for studying its effectiveness of treating nitrate-containing soil. Nitrates and nitrites are commonly found in surface water and groundwater. These substances, in general, could pose a threat to both organisms in the water bodies and human health. Traditionally, nitrogen oxides in various water bodies are treated by biological denitrification processes. However, it would take a longer time to yield a satisfactory result as compared with physicochemical processes. In recent years, permeable reactive barriers (PRBs) using zero-valent iron have been successfully used for degradation of various compounds including nitrates. Electrokinetic processing (EK) also is considered as an effective in-situ technology for removing both inorganic and organic substances from the treatment zone. In this work, the synthesized nano-scale iron particles were incorporated into a PRB, which was further combined with EK to form a novel process for the degradation of nitrates. Various operating parameters were studied in this work. The nano-sized iron particles were determined to be ranging from 50-80nm in size and having specific surface area of 37.83m2. The isoelctric point of these nanoparticles was found to be at pH 7.3. Experimental results have shown that the best location of the iron wall was 5cm from the anode reservoir. Also, the optimal treatment time would be six days in this study. The treatment efficiency was found to increase with increasing dose of nano-sized iron particles in the PRB. Operating with the polarity reverse would slightly increase the overall treatment efficiency as compared with the case of no polarity reverse (92.38% versus 88.34%). An electric gradient of 1.5V/cm was determined to be the optimal electric field strength in this study. In this work, it was also found that 2.5g nano-scale iron particles outperformed 20g micro-scale iron particles (75-150µm) in terms of nitrate degradation. In a study of using an extended treatment time up to 20 days, the black colored iron wall would fade away becoming a rusty plume toward the cathode as the treatment time elapsed. Furthermore, the Fe2+ concentration was elevated throughout the soil column after the 20-day treatment. Therefore, it is evident that nano-sized iron particles would migrate when they are subjected to EK. Based on the research findings obtained, the novel process employed in this study was found to be an effective one for in-situ treatment of nitrate-containing soil.

The objective of this research was to evaluate the treatment efficiency of a trichloroethylene (TCE) contaminated soil by combined technologies of the suspension of palladized nanoiron and electrokinetic remediation process. First, nanoiron and palladized nanoiron were prepared using the chemical reduction method. Then they were characterized by various methods. Micrographs of scanning electron microscopy have shown that a majority of these nanoparticles were in the range of 50-80 nm. Specific surface areas were determined to be 76.88 m2/g and 100.61 m2/g for the former and latter, respectively. Results of X-ray diffractometry have shown that both types of nanoiron were poor in crystallinity. Three anionic dispersants were employed for evaluating their performance in stabilizing various nanoiron. Results have demonstrated that an addition of 1 wt% of Dispersant E during nanoiron preparation would result in a good stabilization of nanoiron. If the system pH was adjusted to 2.99, nanoparticles would settle rapidly. Batch tests were carried out to investigate the effects of various operating parameters on degradation of TCE in aqueous solutions. Experimental results have indicated that palladized nanoiron outperformed nanoiron in treatment of TCE in this study. The employment of Dispersant E would enhance the treatment efficiency further. Test results also showed that a linear increase of reaction rate constant was found with an increasing dose of palladium from 0.05 wt% to 1 wt% based on the mass of nanoiron. Further, an exponential increase of reaction rate constant would be obtained with an increasing pH. As for mixing intensity, it was found to be insignificant to the treatment efficiency of TCE in aqueous solutions. The final stage of this study was to evaluate the treatment efficiency of combined technologies of the suspension of palladized nanoiron and electrokinetic remediation process in treating a TCE-contaminated soil. Test conditions used were given as follows: (1) initial TCE concentration: 160-181 mg/kg; (2) electric potential gradient: 1 V/cm; (3) daily addition of 20 mL of suspension of palladized nanoiron (2.5 g/L) to the electrode reservoir; and (4) reaction time: 6 days. Test results have shown that addition of palladized iron suspension to the cathode reservoir yielded the lowest residual TCE concentration in soil. Namely, about 92.5% removal of TCE from soil. On the other hand, addition of palladized iron suspension to the anode reservoir would enhance the degradation of TCE therein. Based on the above findings, the treatment method employed in this work was proven to be a novel and efficient one in treating TCE-contaminated soil.