Chemistry Commons^™

Synthesis Of A Series Of Ag(I)-Nhc Complexes For Future Antibacterial Studies, Alyssa Malto

Honors Program Theses

For thousands of years, silver (Ag) has been widely used for medicinal purposes due to its broad-spectrum antimicrobial properties. While medicinal silver usage declined with the advent of antibiotics, there has been a renewed interest in therapeutic silver coordination compounds to combat the spread of antibiotic resistance. N-heterocyclic carbenes (NHCs) are promising ligands for silver metallodrugs due to their wide structural variety that allows for tunability of the complex’s overall steric and electronic properties and previously established bioactivity against various pathogens and cancer cell lines. There is potential for efficacy against biofilms, a type of microbial growth pattern that is …

Convergent Synthesis Of Anaephene B, Megan Johnson

Honors Program Theses

Many organisms are capable of producing organic compounds as secondary metabolites; these natural products can be quite pharmaceutically and medicinally relevant.1 Typically, the more unique an organism, the more unique its secondary metabolites. Cyanobacteria, an abundant microalgal organism, is capable of producing a myriad of novel natural products.2 The unique photosynthetic and autotrophic properties of cyanobacteria allow for the production of many secondary metabolites, including lipopeptides, amino acids, fatty acids, macrolides, amides, and others.2,3 Staphylococcus aureus is one the most common bacterial infections in the world.4 S. aureus produces a number of metabolites that inhibit host immune responses.4 As a …

High Throughput Analysis To Study Emerging Pollutants And Nanoparticle Fate In Biological Systems, Xiaolong He

Doctoral Dissertations

”The increasing applications of emerging and fugitive contaminants (EFCs) and engineered nanoparticles (ENPs) attract significant research interest for their potential risks to human health and the environment. In order to assess the health risks of these emerging contaminants, rapid and reliable analytical methods to measure the concentrations and fates of these contaminants are imperative. This dissertation focuses on the developments of advanced analytical methods and their applications to study those emerging contaminants in crop plant and simulated gastric fluid (SGF). Three types of mass spectrometry based methodologies have been developed, one is freeze-thaw/centrifugation extraction followed by high performance liquid chromatography …

World Oceans: A Reference Handbook, Rob Tench

Libraries Faculty & Staff Publications

Book review of Newton, David, World Oceans: A Reference Handbook, ABC-CLIO. (Contemporary World Issues), Feb. 2021, ISBN 9781440875434.

Design, Synthesis And Applications Of Nanoparticles In Suppression Of Mosquito-Born Flaviviridae Viruses, Maria R. Blahove

College of Graduate Studies: Theses & Dissertations

Recently, nanoparticles have become an origin of exploration in the chemistry field due to their unique medical uses. The current drug delivery models of nanoparticles often include a metal base with a drug conjugated to its surface. However this raises concerns regarding toxicity. A novel approach to solving this dilemma is the development of nanosized biocompatible polymer-based micelles, created from PEG-PCL-PEG triblock polymer, and formed around a drug of choice. The goal is to create a drug carrier nanoparticle system that is labile at a specific intracellular pH, without undue toxicity to the cell. This creates a drug-loaded nanoparticle that …

The Effects Of Nacl On The Triple Helix Structure Of Collagen And The Reinforcement Of Tung Oil-Based Polymers With Collagen Peptides, Christopher Dzorkpata

College of Graduate Studies: Theses & Dissertations

In this research, a collagen-reinforced bio-composite from tung oil was prepared using free radical initiation and thermal polymerization, leading to polyolefinic tung oil-based matrix. Two peptides (long and short) were synthesized and their secondary features were analyzed using circular dichroism spectroscopy. After this analysis, the long peptide exhibited more triple helix characteristics as compared to the short peptide. The full protein will ultimately have a better interaction with the tung oil, was used in the synthesis of the collagen-reinforced bio-composite. The presence of NaCl in the triple helix and its overall effect on the thermal and mechanical properties of the …

Hydroamidation With Acetamides And Trifluoroacetamides, Gordon H. Whitetree

College of Graduate Studies: Theses & Dissertations

The hydroamidation reaction is an attractive methodology for the construction of larger functional molecules. In our research, a baseline reactivity was established for the hydroamidation reaction using a set of N-alkyl and N-aryl (trifluoro)acetamides with methyl acrylate and acrylonitrile, various bases and varying reaction conditions. The combination of alkenes, acetamides, and trifluoroacetamides with base was crucial for reaction rate. N-aryl trifluoroacetamides exhibited near quantitative conversions in neat alkene with Diazabicycloundecene (DBU) as base. The less acidic N-aryl acetamides performed much faster in the presence of KOtBu and conversions of >95% were accomplished regularly but contained a large presence …

Jazz Colors: Pigment Identification In The Gouaches Used By Henri Matisse, Ana Martins, Anne Catherine Prud’Hom, Maroussia Duranton, Abed Haddad, Celine Daher, Anne Genachte-Le Bail, Tiffany Tang

Publications and Research

Jazz, the illustrated book by Henri Matisse, is a testament to the vitality of the artist in the last decade of his career. The book consists of twenty illustrations reproduced in 370 copies using a stencil-based printing technique and the same Linel gouaches the artist had used for the original maquettes. This study reports on the comprehensive analysis carried out to identify the pigments in the gouaches used in Jazz by transmitted and reflectance infrared, Raman, SERS, and X-ray fluorescence spectroscopies, and describes the lightfastness of these gouaches as evaluated by microfaedometry. This study also highlights the necessity of …

Genetic Code Expansion Of Plastic-Degrading Enzymes For Detection Of Microplastics, Jariya Jitdee

Chulalongkorn University Theses and Dissertations (Chula ETD)

Petrochemical plastics can degrade into the size level of microplastics. One source of microplastics is polyethylene terephthalate (PET or PETE). Enzymes used to degrade PET have been reported. In our work, we wish to repurpose the activity of PET-degrading enzymes, into PET-detecting enzymes, and use the engineered enzyme for microplastic detection, via enzyme engineering to create enzyme variants which can form covalent adducts with microplastic particles. The enzyme-microplastic adduct is generated via the use of 2,3-diaminopropionic acid (DAP) derivative, which we will incorporate in place of the catalytic serine residue at the active site of I. sakeinesis—PETase via the genetic …

Development Of Analytical Methods For The Determination Of Β-Lactam Antibiotic Residues In Meat, Milk And Dairy Products, Melissa Di Rocco

Theses

In this project, analytical methodologies for the determination of β-lactam antibiotic residues in meat and dairy products were developed and validated using ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). The methods included the main penicillins, cephalosporins and carbapenems commonly employed in human or veterinary medicine for the treatment of bacterial infections. A multi-residue method for the analysis of 30 β-lactams was developed and validated in bovine muscle using dispersive-solid phase extraction (d-SPE), reversed-phase chromatography and mass spectrometry detection. A number of sorbent materials were assessed for clean-up, and a simple and straightforward sample preparation protocol developed for …

Therapeutic Immunoglobulin G Surface Mobility Promotes Antibody-Dependent Cellular Phagocytosis By Arp2/3 And Syk Mediated Rearrangement Of Fcγ Receptors, Seongwan Jo

Electronic Theses and Dissertations

Therapeutic antibodies are rapidly growing class of drugs for treating cancers and immunological disorders by targeting specific antigens or blocking certain pathway to inhibit the tumor growth. In cancer immunotherapy, it was found that Fcγ receptor (FcγR) in immune cells play an important role in antibody dependent cell toxicity against tumor cells. Therefore, understanding FcγR activation mechanism, which requires ligation with immunoglobulin (IgG), is crucial to enhance potency of therapeutic antibodies. One crucial immune responses triggered upon FcγR ligation with IgG is phagocytosis which indicates clearing targets by engulfment. It is known that FcγRs form microclusters which gets rearranged during …

Analysis Of Volatile Organic Compounds: Petroleum Emissions And Microbial Degradation, A K M Ahsan Ahmed

Electronic Theses and Dissertations

Volatile organic compounds (VOCs) are abundant in nature and can occur in various forms in a wide variety of sources. Petroleum is one of the major sources of VOCs. Petroleum being the most widely used energy resources of the world, often released to the environment due to emission and leakage or accidental spillage during exploration, transportation and manufacturing. Once released to the environment, petroleum poses a serious threat to the environment due to some of its toxic organic components. Therefore, the analysis of petroleum is critical to understand its effect on the environment and remediation. This dissertation is focused on …

College Students Conceptions Of Particulate Nature Of Matter And The Impact On Research Instrumentation, Bridget Klutse

Electronic Theses and Dissertations

The main objective of this research was to explore the understanding and conceptions of Particulate Nature of Matter (PNM) with Chem 115 L students as the participants. Conceptions were defined specifically as beliefs and alternative beliefs about topics. The research also assessed the impact of analytical instrumentation in the chemistry laboratory on learning chemistry concepts. Eight questions (8) with multiple choice answers were administered to 10 students at the beginning and after the Fall 2018 semester via selective/purposeful sampling. Data were collected using surveys (pre- and post-surveys) and interviews (pre- and postinterviews), then analyzed quantitatively and qualitatively. The eight questions …

Photoluminescence Properties Of Polycyclic Aromatic Sulfur Heterocycles And Their Sorption And Desorption Onto Microplastics., Sadia Arif

Electronic Theses and Dissertations, 2020-2023

Polycyclic aromatic sulfur heterocycles (PASHs) are sulfur analogues of polycyclic aromatic hydrocarbons (PAHs) commonly found in environmental samples exposed to oil contamination. The determination of PASHs in complex samples is far more difficult than PAHs because of the sulfur atom in the heterocyclic ring, which increases the total number of possible isomeric compounds. Since their toxicological properties vary considerably from isomer to isomer, the unambiguous determination of specific isomers in environmental samples is crucial for ecotoxicological purposes and human safety. GC-MS has been the primary analytical technique for the determination of PASHs in environmental samples. Unfortunately, as the number of …

Identification And Detection Of Cosmetics Transferred During Close Personal Attacks, Kandyss Najjar

Electronic Theses and Dissertations, 2020-2023

New types of trace evidence are necessary to account for the potential lack of evidence found during criminal investigations, due to perpetrators' awareness of common types such as latent prints, hair, and DNA. During cases involving close personal contact, such as sexual assault, perpetrators may not be aware of the possible transfer of cosmetics from or onto the victim or crime scene. Therefore, this project focused on analyzing and developing characterization schemes for cosmetic components, specifically glitter and shimmer particles. Analysis of these particles was performed using various analytical techniques, such as microscopy and spectroscopy techniques, and the developed characterization …

Investigation Of Emissions And Chemistry Of Formic Acid And Acetic Acid In Wildfire Smoke, Catherine Elizabeth Wielgasz

Graduate Student Theses, Dissertations, & Professional Papers

Formic acid (HCOOH) and acetic acid (CH₃COOH) are two of the most ubiquitous organic acids in the atmosphere. Chemical transport models consistently underestimate HCOOH and CH₃COOH concentrations in environments including fire smoke, implying our incomplete understanding of their global budget. Emissions and secondary production of HCOOH and CH₃COOH within complex mixtures in fire smoke is uncertain.

I used measurements from the NSF/NCAR C-130 aircraft during the Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption, and Nitrogen (WE-CAN) campaign to investigate emissions and photochemical production of HCOOH and CH₃COOH from smoke plumes. First, …

Development Of A Novel In-Situ Chemical Sampler For Aquatic Systems, Alec W. Johnson

Graduate Student Theses, Dissertations, & Professional Papers

There has been a long-standing need to study Dissolved Organic Carbon (DOC) within aquatic systems. DOC is an important water quality parameter that provides insights into ecological and carbon cycle processes in aquatic systems. DOC is not easily studied due to traditional, labor-intensive sampling methods. Often, optical (e.g. fluorescence) proxy estimations for DOC are used instead of directly sampling for DOC. Using either low frequency measurements or proxy estimations for DOC can lead to inadequate understanding of the natural processes that control DOC in aquatic systems.

This thesis outlines a in-situ sampler that will be capable of collecting, preserving, and …

Fluid Model Of Plasma-Liquid Interaction: The Effect Of Interfacial Boundary Conditions And Henry's Law Constants, Yifan Liu, Dingxin Liu, Jishen Zhang, Bowen Sun, Santu Luo, Hao Zhang, Li Guo, Mingzhe Rong, Michael G. Kong

Bioelectrics Publications

Plasma–liquid interaction is a critical area of plasma science, mainly because much remains unknown about the physicochemical processes occurring at the plasma–liquid interface. Besides a lot of experimental studies toward the interaction, a few fluid models have also been reported in recent years. However, the interfacial boundary conditions in the models are different and the Henry's law constants therein are uncertain; hence, the accuracy and robustness of the simulation results are doubtable. In view of this, three 1D fluid models are developed for the interaction between a plasma jet and deionized water, each of which has a unique interfacial boundary …

Oxygen Harvesting From Carbon Dioxide: Simultaneous Epoxidation And Co Formation, Han Xu, Muhammad Shaban, Sui Wang, Anas Alkayal, Dingxin Liu, Michael G. Kong, Felix Plasser, Benjamin R. Buckley, Felipe Iza

Bioelectrics Publications

Due to increasing concentrations in the atmosphere, carbon dioxide has, in recent times, been targeted for utilisation (Carbon Capture Utilisation and Storage, CCUS). In particular, the production of CO from CO₂ has been an area of intense interest, particularly since the CO can be utilized in Fischer–Tropsch synthesis. Herein we report that CO₂ can also be used as a source of atomic oxygen that is efficiently harvested and used as a waste-free terminal oxidant for the oxidation of alkenes to epoxides. Simultaneously, the process yields CO. Utilization of the atomic oxygen does not only generate a valuable product, …

Discharge Mode Transition In He/Ar Atmospheric Pressure Plasma Jet And Its Inactivation Effect Against Tumor Cells In Vitro, Bolun Pang, Zhijie Liu, Sitao Wang, Yuting Gao, Huaiyan Zhang, Feng Zhang, Xiamin Tantai, Dehui Xu, Dingxin Liu, Michael G. Kong

Bioelectrics Publications

Discharge characteristic comparisons between He and Ar plasma jets have been extensively reported, but is rarely reported for the comprehensive study of discharge mode transition from He jet to Ar jet, especially its induced liquid chemistry and biological effect. In this paper, we investigate the plasma jet mode transformation by varying the Ar contents in the He/Ar mixing working gas, particularly focusing on the effect of liquid chemistry of plasma activated water (PAW) and the corresponding inactivation effect against tumor cells in vitro. The mode transition process from He jet to Ar jet is characterized by the discharge images, …

Probing Liquid−Liquid Phase Separation In Secondary Organic Aerosol Mimicking Solutions Using Articulated Straws, Emmaline R. Longnecker, Lucy Metz, Rebecca S. Miller, Andrew E. Berke

Chemistry: Faculty Publications

The presence or absence of liquid–liquid phase separation (LLPS) in aerosol particles containing oxidized organic species and inorganic salts affects particle morphology and influences uptake into, diffusion through, and reactivity within those particles. We report here an accessible method, similar to ice core analyses, using solutions that are relevant for both aerosol chemical systems and aqueous two-phase extraction systems and contain ammonium sulfate and one of eight alcohols (methanol, ethanol, 1-propanol, 2-propanol, 2-butaonol, 3-methyl-2-butanol, 1,2-propanediol, or 1,3-propanediol) frozen in articulated (bendable) straws to probe LLPS. For alcohols with negative octanol–water partitioning coefficient (KOW) values and O/C ratios ≥0.5, …

The Quantitative Assessment Of Pond Scum: An Examination Of The Biogeochemistry Of Phosphorus Cycling In The Belgrade Lakes, Abbey M. Sykes

Honors Theses

The internal recycling phosphorus in freshwater lake bottom sediments represents a significant source of hypolimnetic phosphorus (P) release for many of Maine’s lakes. In summer months, Maine lakes often thermally stratify and the lake hypolimnion develops anoxia, leading to a reduction in redox potential at the sediment-water interface. These reducing conditions facilitate the reductive dissolution of ferric iron, and, since phosphorus is often present in freshwater lake sediments as solid FeOOH-PO₄ complexes, results in release of soluble phosphorus into the water column. Our current study presents field and laboratory data from sediment fractionation extractions designed to quantify concentrations of …

Pore Water Exchange-Driven Inorganic Carbon Export From Intertidal Salt Marshes, Joeseph J. Tamborski, Meagan Eagle, Barret L. Kurylyk, Kevin D. Kroeger, Zhaoihui Aleck Wang, Paul Henderson, Matthew A. Charette

OES Faculty Publications

Respiration in intertidal salt marshes generates dissolved inorganic carbon (DIC) that is exported to the coastal ocean by tidal exchange with the marsh platform. Understanding the link between physical drivers of water exchange and chemical flux is a key to constraining coastal wetland contributions to regional carbon budgets. The spatial and temporal (seasonal, annual) variability of marsh pore water exchange and DIC export was assessed from a microtidal salt marsh (Sage Lot Pond, Massachusetts). Spatial variability was constrained from ²²⁴Ra : ²²⁸Th disequilibria across two hydrologic units within the marsh sediments. Disequilibrium between the more soluble ²²⁴Ra …

Toward Resolving Disparate Accounts Of The Extent And Magnitude Of Nitrogen Fixation In The Eastern Tropical South Pacific Oxygen Deficient Zone, Corday R. Selden, Margaret R. Mulholland, Brittany Widner, Peter Bernhardt, Amal Jayakumar

OES Faculty Publications

Examination of dinitrogen (N₂) fixation in the Eastern Tropical South Pacific oxygen deficient zone has raised questions about the range of diazotrophs in the deep sea and their quantitative importance as a source of new nitrogen globally. However, technical considerations in the deployment of stable isotopes in quantifying N₂ fixation rates have complicated interpretation of this research. Here, we report the findings of a comprehensive survey of N₂ fixation within, above and below the Eastern Tropical South Pacific oxygen deficient zone. N₂ fixation rates were measured using a robust ¹⁵N tracer method (bubble removal) …

Artificial Reefs: A History, A Science, A Technology, Mairead D. Farrell

Honors Theses

Over the past 60 years, artificial reefs have expanded beyond the definition of a technology, and in turn have developed into a unique branch of marine science. To better emphasize this growth and separation, a brief history of artificial reef development and usage in chapter two shows some of the key shifts over time in this technology’s purpose and the materials used to achieve that goal. Likewise, to indicate the scientific development of artificial reefs as a branch of marine science, their usage for discovery and research is recorded in chapter three, along with the exponential increase in published scientific …

Radium Isotopes As Submarine Groundwater Discharge (Sgd) Tracers: Review And Recommendations, J. Garcia-Orellana, V. Rodellas, Joseph Tamborski, M. Diego-Feliu, P. Van Beek, Y. Weinstein, M. Charette, A. Alorda-Kleinglass, H.A. Michael, T. Stieglitz, J. Scholten

OES Faculty Publications

Submarine groundwater discharge (SGD) is now recognized as an important process of the hydrological cycle worldwide and plays a major role as a conveyor of dissolved compounds to the ocean. Naturally occurring radium isotopes (Ra-223, Ra-224, Ra-226 and Ra-228) are widely employed geochemical tracers in marine environments. Whilst Ra isotopes were initially predominantly applied to study open ocean processes and fluxes across the continental margins, their most common application in the marine environment has undoubtedly become the identification and quantification of SGD. This review focuses on the application of Ra isotopes as tracers of SGD and associated inputs of water …

Taxonomic And Nutrient Controls On Phytoplankton Iron Quotas In The Ocean, Benjamin S. Twining, Olga Antipova, P. Dreux Chappell, Natalie R. Cohen, Jeremy E. Jacquot, Elizabeth L. Mann, Adrian Marchetti, Daniel C. Ohnemus, Sara Rauschenberg, Alessandro Tagliabue

OES Faculty Publications

Phytoplankton iron contents (i.e., quotas) directly link biogeochemical cycles of iron and carbon and drive patterns of nutrient limitation, recycling, and export. Ocean biogeochemical models typically assume that iron quotas are either static or controlled by dissolved iron availability. We measured iron quotas in phytoplankton communities across nutrient gradients in the Pacific Ocean and found that quotas diverged significantly in taxon‐specific ways from laboratory‐derived predictions. Iron quotas varied 40‐fold across nutrient gradients, and nitrogen‐limitation allowed diatoms to accumulate fivefold more iron than co‐occurring flagellates even under low iron availability. Modeling indicates such “luxury” uptake is common in large regions of …

Synthesis Of Modified Nickel Iron Layered Double Hydroxides To Enhance Electrochemical Properties For Supercapacitor, Machima Mongkhonratanachai

Chulalongkorn University Theses and Dissertations (Chula ETD)

This research aimed to synthesize Mn-doped NiFe LDHs in order to decrease resistivity, which can result in an increase in specific capacity. Mn-doped NiFe LDHs were synthesized using simple coprecipitation method at 50 oC for 6 hours. Their characteristics were confirmed by ICP, XRD, SEM-EDX and FTIR. Electrochemical measurements such as CV and GCD were employed to evaluate their specific capacities. Current voltage relationship and EIS were used to analyse electrochemical properties and resistivities. Through the doping manganese, the specific capacity could be altered. Investigated by CV, the specific capacity of Ni: Fe: Mn 3: 2: 0.98 and 3: 2: …

นาโนคอมพอสิตของยางธรรมชาติอิพอกซิไดส์/นาโนเซลลูโลสสกัดจากผักตบชวา, ชุติเดช ทองดีเลิศ

Chulalongkorn University Theses and Dissertations (Chula ETD)

ในงานวิจัยนี้ได้เตรียมนาโนคอมพอสิตของยางธรรมชาติอิพอกซิไดส์/นาโนเซลลูโลส โดยเริ่มจากการสังเคราะห์ยางธรรมชาติอิพอกซิไดส์ผ่านกระบวนการอิพอกซิเดชันของน้ำยางธรรมชาติ พบว่ามีปริมาณหมู่อิพอกไซด์ร้อยละ 31 โดยโมล ต่อมาทำการเตรียมนาโนเซลลูโลสจากผักตบชวาโดยเตรียมเซลลูโลสนาโนไฟเบอร์ และเซลลูโลสนาโนคริสตัลจากการไฮโดรไลซิสเซลลูโลสนาโนไฟเบอร์ด้วยกรดที่ความเข้มข้นต่าง ๆ จากการวิเคราะห์โครงสร้างผลึกพบว่าเซลลูโลสนาโนคริสตัลมีปริมาณผลึกมากกว่าเซลลูโลสนาโนไฟเบอร์ และปริมาณผลึกเพิ่มขึ้นเมื่อเพิ่มความเข้มข้นของกรดมากขึ้น และเมื่อทำการเตรียมนาโนคอมพอสิตของยางธรรมชาติอิพอกซิไดส์/นาโนเซลลูโลส พบว่าการใส่นาโนเซลลูโลสมีส่วนช่วยในการปรับปรุงสมบัติด้านความทนแรงดึงและความทนน้ำมันของนาโนคอมพอสิตเมื่อเทียบกับยางธรรมชาติและยางธรรมชาติอิพอกซิไดส์ หากแต่เสถียรภาพทางความร้อนของนาโนคอมพอสิตไม่มีการเปลี่ยนแปลง ซึ่งจากการเตรียมนาโนคอมพอสิตของยางธรรมชาติอิพอกซิไดส์/เซลลูโลสนาโนไฟเบอร์ (ปริมาณ 0.5–3 ส่วนต่อยางร้อยส่วน) พบว่านาโนคอมพอสิตที่ใส่เซลลูโลสนาโนไฟเบอร์ปริมาณ 2 ส่วนต่อยางร้อยส่วน แสดงสมบัติด้านความทนแรงดึงและความทนน้ำมันสูงกว่ายางธรรมชาติอิพอกซิไดส์ 1.80 และ 1.39 เท่า ตามลำดับ จากนั้นนำนาโนคอมพอสิตของยางธรรมชาติอิพอกซิไดส์/เซลลูโลสนาโนไฟ-เบอร์ไปเปรียบเทียบกับนาโนคอมพอสิตของยางธรรมชาติอิพอกซิไดส์/เซลลูโลสนาโนคริสตัลที่มีการไฮโดรไลซิสที่ความเข้มข้นของกรดต่าง ๆ ที่ปริมาณ 2 ส่วนต่อยางร้อยส่วน พบว่านาโนคอมพอสิตที่มีการใส่เซลลูโลสนาโนคริสตัลที่ไฮโดรไลซิสด้วยกรดความเข้มข้น 5 โมลาร์ มีสมบัติด้านความทนแรงดึงและความทนน้ำมันสูงที่สุด โดยมีค่าความทนแรงดึงและมอดุลัสที่ความเครียดร้อยละ 300 มีค่าเพิ่มขึ้น 1.89 และ 2 เท่า ตามลำดับ เมื่อเทียบกับยางธรรมชาติอิพอกซิไดส์ นอกจากนี้เมื่อทำการเปรียบเทียบกระบวนการผสมแบบเลเท็กซ์คอมพาวด์และ ‘อินซิทู’ พบว่ากระบวนการผสมแบบเลเท็กซ์คอมพาวด์มีสมบัติด้านความทนแรงดึงและความทนน้ำมันที่สูงกว่ากระบวนการผสมแบบ ‘อินซิทู’ เมื่อพิจารณาที่ปริมาณเซลลูโลนาโนคริสตัลในนาโนคอมพอสิตเท่า ๆ กัน

ตัวดูดซับคอปเปอร์(Ii) ไอออนที่เตรียมจากยางรถยนต์ใช้แล้ว, พิมลวัลย์ บุญโกย

Chulalongkorn University Theses and Dissertations (Chula ETD)

งานวิจัยนี้มีวัตถุประสงค์เพื่อพัฒนาตัวดูดซับคอปเปอร์(II) ไอออน (Cu(II)) จากยางรถยนต์ใช้แล้ว (WTR) โดยการปรับปรุงผิว WTR ด้วยวิธีต่างกัน ได้แก่ การปรับปรุงผิวด้วยการเผา วิธีทางเคมี และแบบสองขั้นตอน โดยการปรับปรุงด้วยการเผาที่อุณหภูมิต่างกันคือ 320, 370 และ 400 องศาเซลเซียส การปรับปรุงผิวด้วยวิธีทางเคมีโดยการรีฟลักซ์ด้วยสารละลายกรดไนตริกที่เวลาต่างกันคือ 30, 60 และ 180 นาที และการปรับปรุงผิวแบบสองขั้นตอนคือการปรับปรุงผิวด้วยวิธีการเผาและวิธีทางเคมีร่วมกัน อีกทั้งงานวิจัยนี้ยังพัฒนาตัวดูดซับถ่านคาร์บอนซึ่งได้จากการเผาที่ 400 องศาเซลเซียส (h400-WTR) เป็นตัวดูดซับถ่านกัมมันต์ทั้งในรูปแบบผง (ac-WTR/powder) และแบบก้อน (ac-WTR/cube) โดยการกระตุ้นด้วยสารละลายกรดไนตริก ที่อุณหภูมิ 700 องศาเซลเซียส จากการทดลองพบว่าตัวดูดซับ h400-WTR มีความสามารถในการดูดซับมากที่สุดถึง 85% ซึ่งมากกว่าความสามารถในตัวดูดซับอื่น เป็นไปได้ว่ามีรูพรุนหรือพื้นที่ในการยึดเกาะกับ Cu(II) มากกว่าตัวดูดซับจากการปรับปรุงผิวด้วยวิธีทางเคมีและการปรับปรุงผิวแบบสองขั้นตอน โดยตัวดูดซับที่ปรับปรุงด้วยการเผาหรือด้วยวิธีทางเคมีนั้นไม่พบการปลดปล่อย Cu(II) ออกสู่น้ำกลั่นที่ทดสอบ ถ่านกัมมันต์แบบผงและแบบก้อนในงานวิจัยนี้มีพื้นที่ผิวจำเพาะต่ำกว่ามาตรฐานของถ่านกัมมันต์ แต่อย่างไรก็ตามตัวดูดซับถ่านกัมมันต์แบบผงที่เตรียมได้สามารถดูดซับ Cu(II) ไอออนสูงถึง 100% และมีค่าการดูดซับมากกว่าตัวดูดซับถ่านคาร์บอนทุกชนิด ทั้งนี้อาจเนื่องจากพื้นที่ผิวที่เพิ่มมากขึ้นจากการกระตุ้นด้วยกรดไนตริก โดยแบบก้อนดูดซับที่ 54% ซึ่งสามารถใช้งานในรูปแบบก้อนในน้ำได้โดยไม่แตกสลายใน 24 ชั่วโมง จึงน่าสนใจในการนำไปใช้งานกรณีที่การใช้งานไม่เหมาะกับแบบผง