Efficient CO2 Sorbents Based on Silica Foam with Ultra-large Mesopores

A series of high-capacity, amine impregnated sorbents based on a cost-effective silica foam with ultra-large mesopores is reported. The sorbents exhibit fast CO2 capture kinetics, high adsorption capacity (of up to 5.8 mmol g−1 under 1 atm of dry CO2), as well as good stability over multiple adsorption–desorption cycles. A simple theoretical analysis is provided relating the support structure to sorbent performance.This publication was based on work supported by Award no. KUS-C1-018-02, made by King Abdullah University of Science and Technology (KAUST)

High efficiency nanocomposite sorbents for CO2 capture based on amine-functionalized mesoporous capsules

A novel high efficiency nanocomposite sorbent for CO2 capture has been developed based on oligomeric amine (polyethylenimine, PEI, and tetraethylenepentamine, TEPA) functionalized mesoporous silica capsules. The newly synthesized sorbents exhibit extraordinary capture capacity up to 7.9 mmol g-1 under simulated flue gas conditions (pre-humidified 10% CO2). The CO2 capture kinetics were found to be fast and reached 90% of the total capacities within the first few minutes. The effects of the mesoporous capsule features such as particle size and shell thickness on CO2 capture capacity were investigated. Larger particle size, higher interior void volume and thinner mesoporous shell thickness all improved the CO2 capacity of the sorbents. PEI impregnated sorbents showed good reversibility and stability during cyclic adsorption-regeneration tests (50 cycles)

Using Magnetically Responsive Tea Waste to Remove Lead in Waters under Environmentally Relevant Conditions

We report the use of a simple yet highly effective magnetite-waste tea composite to remove lead(II) (Pb[superscript 2+]) ions from water. Magnetite-waste tea composites were dispersed in four different types of water–deionized (DI), artificial rainwater, artificial groundwater and artificial freshwater–that mimic actual environmental conditions. The water samples had varying initial concentrations (0.16–5.55 ppm) of Pb[superscript 2+] ions and were mixed with the magnetite-waste tea composite for at least 24 hours to allow adsorption of the Pb[superscript 2+] ions to reach equilibrium. The magnetite-waste tea composites were stable in all the water samples for at least 3 months and could be easily removed from the aqueous media via the use of permanent magnets. We detected no significant leaching of iron (Fe) ions into the water from the magnetite-waste tea composites. The percentage of Pb adsorbed onto the magnetite-waste tea composite ranged from ~70% to 100%; the composites were as effective as activated carbon (AC) in removing the Pb[superscript 2+] ions from water, depending on the initial Pb concentration. Our prepared magnetite-waste tea composites show promise as a green, inexpensive and highly effective sorbent for removal of Pb in water under environmentally realistic conditions.SUTD-MIT International Design Center (Research Grant IDG11200105/IDD11200109)Singapore-MIT Allianc

Unconventional radical miniemulsion polymerization

Conventional free-radical miniemulsion polymerization has been well studied since early 1970s. Conventional free-radical miniemulsion polymerizations have inherent limitations associated with uncontrolled free-radical polymerization mechanism. The goal of this work is to develop a variety of unconventional miniemulsion polymerization techniques by applying new polymerization techniques (typically in solution or bulk) to miniemulsion systems to overcome their inherent limitations and extend the application of free-radical miniemulsion polymerization. This work focused on the exploration of kinetic and mechanistic aspects of unconventional miniemulsion polymerizations. First, enzyme initiated free-radical miniemulsion polymerization, in contrast with those conventional chemical initiated miniemulsion polymerization, is demonstrated for the first time as an answer to the challenges associated with using the hydrophobic of vinyl monomers in aqueous enzymatic reactions. A procedure for enzyme initiated free-radical miniemulsion polymerization was formulated and stable poly(styrene) latexes were successfully synthesized. The kinetics of enzyme initiated free-radical miniemulsion polymerization and the effect of reaction conditions on the polymerization was elucidated. Second, RAFT miniemulsion polymerization of hydrophobic monomers was performed in CSTR trains and the transient states, previously identified by others in our group, were elucidated. Next, RAFT miniemulsion polymerization of a partially water soluble monomer was studied. RAFT miniemulsion polymerizations of gamma-methyl-alpha-methylene-gamma-butyrolactone, a partially water soluble lactone monomer derived from renewable sources, was successfully formulated. Homogeneous nucleation was found to play an important role in the free-radical "miniemulsion" homopolymerization of MeMBL. By using styrene as a comonomer, the RAFT miniemulsion polymerizations of MeMBL and styrene were well controlled and narrowly distributed copolymers of MeMBL/styrene were produced. Following the study of the partially water monomer, RAFT inverse miniemulsion polymerization was proposed for the polymerization of hydrophilic monomers. The kinetics of RAFT inverse miniemulsion polymerization of acrylamide exhibited the typical behavior of controlled polymerizations up to high conversions. The effects of reaction parameters on the polymerization rate and particle size were investigated. The dominant locus of radical generation for particle nucleation and the fate of desorbed monomeric radicals in inverse miniemulsion polymerizations were evaluated. Finally in this work, conclusions and implications are presented and ideas for future work are suggested.Ph.D.Committee Chair: Jones, Christopher W.; Committee Chair: Schork, F. Joseph; Committee Member: Koros, William J.; Committee Member: Lyon, Andrew; Committee Member: Nenes, Athanasio

Superhydrophilic Wrinkle-Free Cotton Fabrics via Plasma and Nanofluid Treatment

We demonstrate in this study a wrinkle-free, superhydrophilic cotton fabric (contact angle ∼0°) by uniformly attaching specially engineered nanoparticles to plasma-pretreated cotton fabric. Because of their highly charged nature, the nanoparticles are firmly anchored on the fabric via electrostatic interactions, as confirmed by microscopy and chemical analyses. The durability of wetting behavior and wrinkle-free property of the nanoparticle-coated fabrics were evaluated via aging, laundering, and abrasion tests. The strongly attached coatings are stable enough to maintain their superhydrophilic nature even after 60 days of aging at room temperature, 50 laundering cycles, and 25 000 abrasion cycles. Moreover, the nanoparticle-coated superhydrophilic fabrics exhibit great wrinkle-recovery property, tensile strength, and abrasion resistance performance up to 25 000 abrasion cycles

Patch Based Grid Artifact Suppressing in Digital Mammography

The mammography is the first choice of breast cancer screening, which has proven to be the most effective screening method. An antiscatter grid is usually employed to enhance the contrast of image by absorbing unexpected scattered signals. However, the grid pattern casts shadows and grid artifacts, which severely degrade the image quality. To solve the problem, we propose the patch based frequency signal filtering for fast grid artifacts suppressing. As opposed to whole image processing synchronously, the proposed method divides image into a number of blocks for tuning filter simultaneously, which reduces the frequency interference among image blocks and saves computation time by multithread processing. Moreover, for mitigating grid artifacts more precisely, characteristic peak detection is employed in each block automatically, which can accurately identify the location of the antiscatter grid and its motion pattern. Qualitative and quantitative studies were performed on simulation and real machine data to validate the proposed method. The results show great potential for fast suppressing grid artifacts and generating high quality of digital mammography

Phyllosilicate nanoclay-based aqueous nanoparticle sorbent for CO2 capture at ambient conditions

We report a new and effective aqueous sorbent for CO2 capture at ambient conditions based on aminopropyl magnesium phyllosilicate nanoparticles (aminoclay). Combining the advantages of both liquid and solid amine sorbents, the aminoclay sorbent is easy to synthesize, and exhibits CO2 recuperation capacity of ?4 mmol/g at steady state and reduced sorbent loss due to volatility making it a promising candidate for carbon capture technologies. 1 2017 Elsevier LtdWe gratefully acknowledge support from NPRP Grant # 5-1437-1-243 from Qatar National Research Fund . Datta and Zboril acknowledge the support by the Ministry of Education, Youth and Sports of the Czech Republic ( LO1305 ) and the authors also acknowledge the assistance provided by the Research Infrastructure NanoEnviCz, supported by the Ministry of Education, Youth and Sports of the Czech Republic under Project No. LM2015073.Scopu

Formation of SnO2 hollow nanospheres inside mesoporous silica nanoreactors

We report an interesting approach for efficient synthesis of SnO2 hollow spheres inside mesoporous silica “nanoreactors”. The as-prepared products are shown to have a uniform size distribution and good structural stability. When evaluated for their lithium storage properties, these SnO2 hollow spheres manifest improved capacity retention.Accepted versio