This thesis presents solid phase extraction (SPE) methodologies based on mixed-mode polymeric sorbents; a mixed mode strong anion exchanger (Agilent SampliQ SAX) and a mixed mode strong cation exchanger (Agilent SampliQ SCX). Furthermore, dispersive-SPE based on a quick, easy, cheap, effective, rugged and safe (QuEChERS) method was assessed for applicability in the determination of drug residues. The mixed-mode polymeric sorbents were evaluated for the simultaneous fractionation of drugs that exhibit diverse polarities with acidic, basic and neutral functionalities in biological matrices (plasma and urine). The polymeric skeleton of these sorbents entails an exchanger group and therefore provides two retention mechanisms, strong cation or anion exchange retention mechanisms with hydrophobic interactions. It was demonstrated that with a sequential elution protocol for sample clean-up analytes were fractionated into acidic, basic and neutral classes. The SAX was employed for analysis of ketoprofen, naproxen (acidic drugs), nortriptyline (basic) and secobarbital (neutral) from urine sample. The SCX was used for fractionating phenobarbital, p-toluamide (acidic), amphetamine, m-toluidine (basic) and acetaminophen (neutral drug) from plasma sample. QuEChERS method was employed for quantitative determination of 16 polycyclic aromatic hydrocarbons (PAHs) from fish fillets and soil; 9 sulfonamides (SAs) from chicken muscles and acrylamide (AA) in cooking oil. The analyte recoveries ranged from 79.6 - 109% with RSDs ranging from 0.06 - 1.9% at three different fortification levels. Good linearity (r2 > 0.9990) was attained for most analytes. The limits of detection and quantification ranged from 0.03 - 0.84 μg/ml and 0.81 - 1.89 μg/ml respectively for analytes in biological samples. LODs and LOQs for analytes in food and environmental samples ranged from 0.02 to 0.39 and 0.25 to 1.30 ng/g respectively.

The thesis presents the evaluation of polysulfone sorbents for solid phase extraction (SPE) and the development of colorimetric probes for pesticides analysis in water. Through electrospraying and electrospinning techniques, different morphologies of sorbents (particles, beaded fibers and bead-free fibers) were fabricated. The sorbents were morphologically characterized by scanning electron microscopy. Adsorption capacities of sorbents were evaluated by conducting recoveries studies for model pesticides; atrazine, chlorpyrifos and DDT using batch and column SPE modes. Better recovery results were achieved by employing the batch mode of fibers, as values ranged from 98 to 105percent. Further sorbent evaluation was conducted using breakthrough experiments and static experiments. The breakthrough studies indicated that 1700 μL was the sample volume that could be percolated with no breakthrough of the analyte that correspond to a concentration of 150 mg/g of sorbent that can be extracted without any loss of analyte. From static studies, quantities of each model compound adsorbed into the fiber at the equilibrium time were evaluated. The adsorbed atrazine was 65, chlorpyrifos 250 and DDT 400 mg/g of sorbent. Kinetic studies suggested retention mechanism following pseudo first and second order model observed by high correlation coefficients (> 0. 96), demonstrating the fiber affinity to retain both polar and non-polar compounds opening a possibility to be used as sorbent for sample preparation of different classes of pesticides in water. For the second part of the study simple strategies for colorimetric sensing based on silver nanoparticles and polivinylpyrrolidone capped nanoparticles were developed, respectively for atrazine and chlorpyrifos detection. The limits of detection of the methods were 3.32 and 0.88 mg/L for atrazine and chlorpyrifos respectively. The applicability of the probe in real samples was demonstrated by the recoveries studies of tap water varying from 94 to 104 percent. The versatility of the probe was demonstrated by affording a simple, rapid and selective detection of atrazine and chlorpyrifos in the presence of other pesticides by direct analysis without employing any sample handling steps. Attempt to incorporate the probes in a solid support was achieved by using nylon 6 as solid support polymer proving to be fast and useful for on-site detection.

The work described in the thesis seeks to lay a foundation for a better understanding of the use of electrospun nanofibers as a sorbent material. Three miniaturised electrospun nanofiber based solid phase extraction devices were fabricated. For the first two, 10 mg of electrospun polystyrene fibers were used as a sorbent bed for a micro column SPE device (8 mm bed height in a 200 μl pipette tip) and a disk (I) SPE device (5 mm 1 mm sorbent bed in a 1000 μl SPE barrel). While for the third, 4.6 mg of electrospun nylon nanofibers were used as a sorbent bed for a disk (II) SPE device, (sorbent bed consisting of 5 5 mm 350 μm stacked disks in a 500 μl SPE barrel). Corticosteroids were employed as model analytes for performance evaluation of the fabricated SPE devices. Quantitative recoveries (45.5-124.29 percent) were achieved for all SPE devices at a loading volume of 100 μl and analyte concentration of 500 ng ml-1. Three mathematical models; the Boltzmann, Weibull five parameter and the Sigmoid three parameter were employed to describe the break through profiles of each of the sorbent beds. The micro column SPE device exhibited a breakthrough volume of 1400 μl, and theoretical plates (7.98-9.1) while disk (I) SPE device exhibited 400-500 μl and 1.39-2.82 respectively. Disk (II) SPE device exhibited a breakthrough volume of 200 μl and theoretical plates 0.38-1.15. It was proposed that the formats of future electrospun nanofiber sorbent based SPE devices will be guided by mechanical strength of the polymer. The study classified electrospun polymer fibers into two as polystyrene type (relatively low mechanical strength) and nylon type (relatively high mechanical strength).

Bidentate imidazole-based extractants, 1-octylimidazole-2-aldoxime (OIMOX) and 1-octyl-2-(2′-pyridyl)imidazole (OPIM), along with dinonylnaphthalene sulfonic acid (DNNSA) as a synergist, were investigated as potential selective extractants for Cu²⁺and Ni²⁺ respectively from base metals in a solvent extraction system. The study was extended to evaluate the sorption and separation of Ni²⁺ from other base metals in a solid-solution system using microspherical Merrifield resins and nanofibers functionalized with 2,2′-pyridylimidazole. Copper was effectively separated with OIMOX and DNNSA as extractants from nickel with ΔpH½ ≈1.05 and the extraction order of Cu²⁺ > Ni²⁺ > Zn²⁺ > Cd²⁺> Co²⁺ was achieved as a function of pH. At pH 1.65 the extracted copper, from a synthetic mixture of the base metals reached 90.13(±0.90)%, and through a two-step extraction process 98.22(±0.29)% copper was recovered with negligible nickel and cobalt impurities. Stripping of the copper from the loaded organic phase using TraceSelect sulphuric acid at pH 0.35 yielded 96.60(±0.44)% of the loaded quantity after the second stage of stripping. The separation of Ni²⁺ from the borderline and hard acids; Co²⁺, Cu²⁺, Zn²⁺, Fe2²⁺, Fe²⁺, Mn²⁺, Mg2²⁺ and Ca²⁺ at a pH range of 0.5-3.5 with OPIM and DNNSA was acvieved to the tune of a ΔpH½≈ 1.6 with respect to cobalt from a sulfate and sulfate/chloride media. A three-stage counter-current extraction of Ni²⁺, at the optimized pH of 1.89, from a synthetic mixture of Ni²⁺, Co²⁺ and Cu²⁺, yielded 99.01(±1.79)%. The total co-extracted Cu²⁺ was 48.72(±0.24)% of the original quantity in the mixture, and it was 19.85(±0.28%) for Co²⁺. The co-extracted Cu²⁺ was scrubbed off from the loaded organic phase at pH≈8.5 by using an ammonium buffer, while co-extracted Co²⁺ was selectively and quantitatively stripped with H₂SO₄ at pH 1.64. The total recovery of Ni²⁺ by stripping at pH 0.32 was 94.05(±1.70)%. In the solid-liquid system, Ni²⁺ was separated from Co²⁺, Cu²⁺, and Fe²⁺ with the microspherical resins funtionalised with 2,2′-pyridylimidazole by a separation factor (β) in the range 22-45. Electrospun nanofibers as sorbents yielded high sorption capacity in the range of 0.97 - 1.45 mmol.g⁻¹ for the same metals ions. Thus, 1-octylimidazole-2-aldoxime (OIMOX), and1-octyl-2-(2′-pyridyl)imidazole (OPIM) can be effectively utilized alongside DNNSA as a co-extractant in the separation of Cu²⁺ and Ni²⁺ respectively from base metals in acidic sulfate medium in a solvent extraction process, and the latter as a selective ligand in the solid-liquid separation of Ni²⁺ from Co²⁺, Cu²⁺, and Fe²⁺.

The increasing concentration of CO2 in the atmosphere and the rapidly growing amount of waste (industrial and electronic) are two major environmental challenges faced by humanity today. Carbon capture, storage, and utilization (CCUS) aims to address the CO2 challenge and has been shown to be a promising means of CO2 mitigation. For carbon capture, amine scrubbing is an example of an effective means to separate CO2 from other gases, particularly natural gas and hydrogen. Carbon storage entails the injection of CO2 into natural geologic formations, such as basalt, to form permanent, harmless carbonates. Lastly, carbon utilization involves conversion of carbon to chemicals and fuels through a variety of pathways, such as carbon mineralization. Many large-scale projects on CCUS have been conducted, with ongoing research in the aforementioned areas of CCUS. The first half of this dissertation addresses carbon storage and utilization, specifically focusing on carbon mineralization, in order to evaluate the potential for CO2 storage in basalt and CO2 utilization in the transformation of industrial waste to valuable carbonates. The mounting amount of electronic waste (e-waste) presents a significant challenge in the flow of valuable elements, especially as it relates to the materials cycle. E-waste contains valuable metals, such as copper, gold, silver, iron, and nickel, and contains much higher amounts of these metals than the amounts found in ores. Thus, the recycling of metals from e-waste is favorable and has gained attention over the last few years. E-waste is a complex mixture of metals, plastics, and refractory materials. The brominated flame retardants in the e-waste are of particular concern as they become hazardous when burned. Lead is also often found in the solder material of e-waste. The risks associated with the toxic and hazardous components of e-waste, along with the heterogeneity in composition, challenge the development of recycling and processing methods for e-waste. While recent developments, such as hydrometallurgy i.e. chemical leaching, have lessened the hazards during processing, pyrometallurgical techniques, which involve smelting, remain the most commonly used treatment. Metal extraction and recovery processes are multi-step techniques that usually involve energy-intensive mechanical processing, and depending on the type of waste, the selectivity of metal separation processes can be quite low. Specifically, for Lithium-ion batteries (LIB), the majority of recycling techniques cannot recover Co and Ni simultaneously. The latter half of this dissertation explores new, sustainable separation processes for the recovery of metals from e-waste, Printed circuit boards (PCB) and LIB, via morphological changes induced by supercritical CO2 and via electrochemical techniques. Chapter 2 presents an evaluation of the potential of sub-seafloor basalt in the Cascadia Basin offshore Washington State and British Columbia for CO2 storage. Basalt samples from the Cascadia Basin were tested for the extraction of Ca, Mg, and Fe to assess the ability of the basalt to form carbonates under the experimental conditions of injection with CO2. Combining laboratory results with modeling studies from collaborators, and comparisons to existing data on the reactivity of oceanic basalt demonstrated that the basalt formations in the Cascadia Basin are a feasible option for large-scale, permanent CO2 storage. In Chapter 3, the reaction of CO2 and industrial waste for Ca and Mg extraction, is investigated in greater detail in the tailored synthesis of high purity precipitate calcium carbonate (PCC) from slag. Different ligands were studied for the extraction of Ca and Mg and various experimental conditions, such as heating, controlling the pH, and bubbling with air vs. CO2 were studied for the formation of calcium carbonates from the steel slag. A novel synthesis method involving the dissolution of the slag using ligands, heating, and precipitation via bubbling with air or CO2 using the Ca-rich solution derived from dissolution, was developed. High purity PCC was successfully produced, making the proposed synthesis process a promising pathway for carbon management and sustainable waste transformation. In Chapter 4, a critical review of current metal extraction and recovery techniques for the treatment and processing of electronic waste is presented. The complexity of e-waste requires the development of new metallurgical processes that can separate and extract metals from unconventional components such as plastics and a wide range of metals. This chapter focuses on the science and engineering of both conventional and innovative separation and recovery technologies for e-waste with special attention given to the overall sustainability. Physical separation processes, including disassembly and magnetic separation, as well as thermal treatment of the polymeric component, such as pyrolysis, are discussed for the separation of metals and non- metals from e-waste. The subsequent metal recovery processes through pyrometallurgy, hydrometallurgy, and biometallurgy are also discussed in depth. Finally, insights on future research towards sustainable treatment and recovery of e-waste are highlighted, including the use of supercritical CO2. Chapter 5 investigates the use of supercritical CO2 for the extraction of metals from electronic waste, specifically Printed circuit boards (PCB). The complexity of PCB was first simplified by synthesizing laminate polymer and metal “model PCB” samples, where the polymer component was polycarbonate (PC) and the metal component was Cu foil. Through controlled studies of the effect of supercritical CO2 (scCO2) and sulfuric acid on the model PCB samples, a thorough understanding of the role of CO2 in the supercritical CO2/co-solvent system was developed. The scCO2/co-solvent system was found to induce permanent, morphological changes in the samples in just 30 minutes. Building on these results, a two-step metal extraction process for waste PCB was proposed. First, the pre-treatment of small pieces of waste PCB with scCO2 and sulfuric acid, and second, chemical leaching at ambient temperature and pressure in a sulfuric acid and hydrogen peroxide solution. This process was demonstrated to yield ~80% Cu extraction in under four hours, without the need for vigorous and energy-intensive mechanical processing, as the starting materials were small pieces of waste PCB, neither shredded nor crushed. The final part of the thesis presents a study on the electrochemical recovery of Co and Ni from spent Lithium-ion batteries (LIB). Galvanostatic deposition and stripping of the metals were performed using a sulfuric acid-based electrolyte with concentrations of Co and Ni based upon waste LIB solution. A complexing agent, specifically EDTA, was introduced into the electrolyte to selectively deposit one metal over the other. The concentration of EDTA was maintained at the concentration of Co and Ni in the solution, and the pH values of the solution were varied to study the effect of pH on the ratio of Co/Ni in the deposit. In the presence of EDTA, the pH of the solution had a significant impact on the ratio of Co/Ni, making the electrochemical process presented in this study an effective, sustainable approach to simultaneous and tunable metal recovery from waste LIBs.

Thesis: M.S., Massachusetts Institute of Technology, Department of Chemical Engineering, 1979 / Includes bibliographical references (leaves 207-212). / by Saeed Tajik. / M.S. / M.S. Massachusetts Institute of Technology, Department of Chemical Engineering

No description available.

No description available.

Polycyclic aromatic hydrocarbons (PAH) are important environmental pollutants originating from a wide variety of natural and anthropogenic sources. Because many of them are highly suspect as etiological agents in human cancer, chemical analysis of PAH is of great environmental and toxicological importance. Current methodology for PAH follows the classical pattern of sample preparation and chromatographic analysis. Sample preparation preconcentrates PAH, simplifies matrix composition, and facilitates analytical resolution in the chromatographic column. Among the several approaches that exist to pre-concentrate PAH from water samples, the Environmental Protection Agency (EPA) recommends the use of solid-phase extraction (SPE). High-performance liquid chromatography (HPLC) and gas chromatographymass spectrometry (GC-MS) are the basis for standard PAH identification and determination. Ultraviolet (UV) absorption and room temperature fluorescence detection are both widely used in HPLC, but the specificity of these detectors is modest. Since PAH identification is solely based on retention times, unambiguous PAH identification requires complete chromatographic resolution of sample components. When HPLC is applied to "unfamiliar" samples, the EPA recommends that a supporting analytical technique such as GC-MS be applied to verify compound identification and to check peak-purity HPLC fractions. Independent of the volume of extracted water, the approximate time required to separate and determine the sixteen "priority pollutants" (EPA-PAH) via HPLC is approximately 60min. If additional GC-MS analysis is required for unambiguous PAH determination, the total analysis time will reach 2-3 hours per sample. If the concentrations of target species are found to lie outside the detector’s response range, the sample must be diluted and the process repeated. These are important considerations iv when routine analysis of numerous samples is contemplated. Parent PAH are relatively inert and need metabolic activation to express their carcinogenicity. By virtue of the rich heterogeneous distribution of metabolic products they produce, PAH provide a full spectrum of the complexity associated with understanding the initial phase of carcinogenesis. PAH metabolites include a variety of products such as expoxides, hydroxyl aromatics, quinines, dihydrodiols, dioepoxides, tetrols and water soluble conjugates. During the past decades tremendous efforts have been made to develop bio-analytical techniques that possess the selectivity and sensitivity for the problem at hand. Depending on the complexity of the sample and the relative concentrations of the targeted metabolites, a combination of sample preparation techniques is often necessary to reach the limits of detection of the instrumental method of analysis. The numerous preparation steps open ample opportunity to metabolite loss and collection of inaccurate data. Separation of metabolites has been accomplished via HPLC, capillary electrophoresis (CE) and GC-MS. Unfortunately, the existence of chemically related metabolic products with virtually identical fragmentation patterns often challenges the specificity of these techniques. This dissertation presents significant improvements in various fronts. Its first original component – which we have named solid-phase nano-extraction (SPNE) - deals with the use of gold nanoparticles (Au NPs) as extracting material for PAH. The advantages of SPNE are demonstrated for the analysis of PAH in water samples via both HPLC1 and Laser-Excited TimeResolved Shpol’skii Spectroscopy (LETRSS).2 The same concept is then extended to the analysis of monohydroxy-PAH in urine samples via SPE- HPLC3 and In-Capillary SPNE-CE.4 The second original component of this dissertation describes the application of Shpol’skii Spectroscopy to the analysis of polar PAH metabolites. The outstanding selectivity and v sensitivity for the direct analysis of PAH at trace concentration levels has made Shpol’skii spectroscopy a leading technique in environmental analysis.5 Unfortunately, the requirement of a specific guest-host combination - typically a non-polar PAH dissolved in an n-alkane - has hindered its widespread application to the field of analytical chemistry. This dissertation takes the first steps in removing this limitation demonstrating its feasibility for the analysis of polar benzo[a]pyrene metabolites in alcohol matrixes.6

M.S.