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Applying Bayesian Machine Learning Methods To Theoretical Surface Science, Shane Carr

McKelvey School of Engineering Theses & Dissertations

Machine learning is a rapidly evolving field in computer science with increasingly many applications to other domains. In this thesis, I present a Bayesian machine learning approach to solving a problem in theoretical surface science: calculating the preferred active site on a catalyst surface for a given adsorbate molecule. I formulate the problem as a low-dimensional objective function. I show how the objective function can be approximated into a certain confidence interval using just one iteration of the self-consistent field (SCF) loop in density functional theory (DFT). I then use Bayesian optimization to perform a global search for the solution. …

Modeling Of Gas Production From Shale Reservoirs Considering Multiple Transport Mechanisms, Chaohua Guo, Mingzhen Wei, Hong Liu

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Gas transport in unconventional shale strata is a multi-mechanism-coupling process that is different from the process observed in conventional reservoirs. In micro fractures which are inborn or induced by hydraulic stimulation, viscous flow dominates. And gas surface diffusion and gas desorption should be further considered in organic nano pores. Also, the Klinkenberg effect should be considered when dealing with the gas transport problem. In addition, following two factors can play significant roles under certain circumstances but have not received enough attention in previous models. During pressure depletion, gas viscosity will change with Knudsen number; and pore radius will increase when …

Mercury Removal From Aqueous Solution Using Natural, Synthetic, And Modified Zeolites, Mahshid Attari

Electronic Thesis and Dissertation Repository

Mercury has been recognized as one of the most hazardous heavy metals. The discharge of effluents containing mercury in soil, sediments and water can inflict an irreversible harm to the environment and human health. In this work, zeolitized coal fly ash as well as gold and gold-iron modified zeolites were successfully employed for mercury removal from a typical industrial wastewater. X-ray diffraction (XRD), thermo-gravimetrical analyses (TGA), surface area measurement (BET), and scanning electron microscopy (SEM-EDX) were utilized to explore the characteristics of the raw and modified zeolites. A pseudo-second-order kinetic model was identified to best represent the kinetic data for …

Solar Photocatalytic Reduction Of Zn2+ Using Graphene-Based Tio2 Composite Catalyst For Application To Cso Treatment, Gloria Kumordzi

Electronic Thesis and Dissertation Repository

The improvement of photocatalyst efficiency in utilizing the majority of wavelengths in the solar spectrum, an abundant natural resource, presents the next step in the large scale application of photocatalysis for the treatment of dissolved organic and inorganic pollutants in wastewater. In this study, a composite catalyst of TiO₂ and Graphene synthesized by a hydrothermal treatment method is used to photo-reduce Zn²⁺, the most abundant heavy metal found in combined sewer overflows (CSOs). The performance of this composite catalyst was assessed under various process conditions such as pH, light intensity, catalyst loading and light source. The TiO …

Functional Clay Nanotubes And Composites, Yafei Zhao

Doctoral Dissertations

Tubular nanomaterials and their composites have been extensively studied in recent years in the fields of physics, chemistry, biology, and biomedicine. Carbon nanotube is the most commonly studied tubular nanomaterial; however, toxicity and high cost make it less attractive in industry and thus restricts its applications. Halloysite nanotubes, which are available in abundance in the United States as well as in other countries around the world, is a low-cost, unique and versatile aluminosilicate mineral with a chemical formula of Al4Si4O10(OH)8·nH2O. Basically, the halloysite tube diameter is around 50 nm and the length varies with different locations ranging from 0.4-1.5 μm. …

Comparative Kinetic Study Of Functionalized Carbon Nanotubes And Magnetic Biochar For Removal Of Cd2+ Ions From Wastewater

Faculty of Engineering University of Malaya

We did a comparative study between functionalized multiwall carbon nanotube (FMWCNTs), and magnetic biochar was carried out to determine the most efficient adsorbent to be employed in the Cd2+ ion removal. We optimized parameters such as agitation speed, contact time, pH and adsorbent dosage using design expert vrsion 6.08. The statistical analysis reveals that optimized condition for highest removal of Cd2+ are at pH 5.0, with dosage 1.0 g, agitation speed and contact time of 100 rpm and 90 minutes, respectively. For the initial concentration of 10mg/l, the removal efficiency of Cd2+ using FMWCNTs was 90% and and 82% of …

Utilization Of Palm Oil Sludge Through Pyrolysis For Bio-Oil And Bio-Char Production

Faculty of Engineering University of Malaya

In this study, pyrolysis technique was utilized for converting palm oil sludge to value added materials: bio-oil (liquid fuel) and bio-char (soil amendment). The bio-oil yield obtained was 27.4 +/- 1.7 wt.% having a heating value of 22.2 +/- 3.7 MJ/kg and a negligible ash content of 0.23 +/- 0.01 wt.%. The pH of bio-oil was in alkaline region. The bio-char yielded 49.9 +/- 0.3 wt.%, which was further investigated for sorption efficiency by adsorbing metal (Cd2+ ions) from water. The removal efficiency of Cd2+ was 89.4 +/- 2%, which was almost similar to the removal efficiency of a commercial …

Physico-Chemical Characterization Of Metal-Doped Bone Chars And Their Adsorption Behavior For Water Defluoridation, Cintia Karina Rojas-Mayorga, Adrian Bonilla-Petriciolet, Joaquín Silvestre-Albero, Ismael A. Aguayo-Villarreal, Didilia I. Mendoza-Castillo

Adrian Bonilla-Petriciolet

New bone chars for fluoride adsorption from drinking water have been synthetized via a metal doping using aluminum and iron salts. A detailed statistical analysis of the metal doping process using the signal-to-noise ratios from Taguchi’s experimental designs and its impact on the fluoride adsorption properties of modified bone chars have been performed. The best conditions, including the proper metallic salt, for metal doping were identified to improve the fluoride uptakes of modified bone chars. Results showed that the fluoride adsorption properties of bone chars can be enhanced up to 600% using aluminum sulfatefor the surface modification. This aluminum-based adsorbent …

Performance Evaluation Of Natural Iron-Rich Sandy Soil As A Low-Cost Adsorbent For Removal Of Lead From Water, Yee Sern Ng, Bhaskar Sen Gupta, Mohd Ali Hashim

Ng Yee-Sern

Technical feasibility of natural iron-rich sandy soil as a low-cost adsorbent for removal of lead from water was investigated . The soil, which had an iron content of 3,719 mg/kg, was collected from Hulu Langat, Malaysia, and was used for adsorption studies without any surface modification through chemical treatment. The effects of pH, solution: soil ratio and initial lead concentration on the adsorption efficiency were studied using response surface methodology based on Box–Behnken experimental design. The results showed that pH of the solution had the highest impact on the adsorption efficiency whereby adsorption efficiency of 97% could be achieved at …

Interfacial Engineering Of Biomass Hydrolysis By Cellulase Enzymes And Mechanistic Modeling Of Hydrolysis Of Cellulose Substrates, Ravinder Kumar Garlapalli

Theses and Dissertations--Chemical and Materials Engineering

Lignocellulosic biomass is a sustainable and renewable energy resource that can be converted to fuels and other commodity chemicals, but this conversion is currently limited by its recalcitrance to enzymatic degradation. Because of this recalcitrance, the major challenges in the commercialization of enzymatic hydrolysis processes are the relatively low hydrolysis rates, limited cellulose conversion under some conditions, and high cost of enzymes.

Enzymatic hydrolysis is influenced by the structure of the biomass after pretreatment and the mode of enzyme action, but has also been shown to be enhanced by surfactant additives. The objective of this work was to elucidate the …