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Research Overview

N2/CH4 Separation

Ultrathin Membranes Composed of 2D Materials for Energy-efficient Separation


All across the world, people are facing a wealth of new and challenging problems, particularly the energy and environmental issues. For example, billions of tons of annual CO2 emissions are the direct result of fossil fuel combustion to generate electricity. According to the Environmental Protection Agency (EPA), the U.S. emitted 6.1 billion metric tons of CO2 to the atmosphere in 2007. Producing clean energy from abundant sources, such as coal, will require a massive infrastructure and highly efficient capture technologies to curb CO2 emissions. In addition to its environmental impact, CO2 also reduces the heating value of the CH4 gas streams in power plants and causes corrosion in pipes and equipment. To minimize the impact of CO2 on the environment, the design of high-performance separation materials and technologies for efficient carbon capture and sequestration (CCS) is urgent and essential. Our research in this area is creating novel nanostructured (membrane) materials with enhanced transport properties by ordering their nano-architectures via different methods and meanwhile exploring their novel and energy-sustainable scale up.

Bioinspired Materials for Water Treatment and Desalination


Oil pollution is another serious global issue because of the large amounts of oily wastewater produced by petrochemical and other industries, as well as by frequent off-shore oil-spill accidents. The Department of Energy and Climate Change (DECC) issues guidance addressed at all companies involved in offshore exploration and production where oil may be released into the sea or other water systems. The regulatory limit for the concentration of oil in produced water discharged into the sea is set at a 30 mg/l performance standard (this figure applies as averaged over a monthly period). At any one time, the concentration must not exceed 100 mg/l. Therefore, it is in great need to develop effective techniques to treat oil-polluted wastewater at such low oil/grease concentrations in order to satisfy the stringent governmental limitations and preserve the environment. Membrane techniques have been widely employed for water purification and are very effective in separating stabilized oil emulsions-especially for removing oil droplets. However, current membranes suffer from membrane fouling both on surfaces and in internal structures, which significantly limits their service time and degrades separation performance in practical operations. My research in this field attempts to adopt the concept of biomimetic hierarchical roughness in membrane design for creating superoleophobic membrane surfaces from a vast pool of candidate materials, such as zeolites, metal-organic frameworks (MOFs), and single-layered graphene oxide. My research also focuses on the development of facile, low-cost preparation technique which would open a completely new direction for the membrane society. Further investigation on scaling-up production/commercialization will be pursued.

Ultrathin membranes for oil/water separation

Hierarchical Nanofabrication of Microporous Materials with Enhanced Hydrothermal Stability for Catalytic Reactions, Adsorption-based Separations and Gas Storage

Enhanced demand for fuels worldwide not only decreased world oil reserves but also increased climate concerns about the use of fossil-based fuel. To address these energy and environmental problems, efforts have been made towards improved utilization of fossil fuel and development of renewable energy production. With the abundant availability and carbon-neutral nature, biomass is recognized as one of the most promising renewable energy resources. A number of transportation fuels can be produced from biomass, helping to alleviate demand for petroleum products and improve the greenhouse gas emissions profile of the transportation sector. Traditional catalysts suffer from many undesirable properties, such as small accessible pore size, low hydrothermal stability, and less controllable active sites. Among these, low hydrothermal stability at upgrading temperatures greatly hinders conversion of lignocellulosic biomass to biofuel. One of my research topics is focused on synthesizing a new class of ultra-stable catalysts with tunable nanostructure and functionalities for efficient bio oil upgrading, with special emphasis on the study of their hydrothermal stability.

Preparation of New Inorganic Porous Materials with Attractive Versatility, Stability, and Biocompatibility to Serve as Controlled Delivery Systems (CDSs) for Small Drug Molecules and Other Biological Agents

The practice of drug delivery has changed dramatically in the last few decades and even greater changes are anticipated in the near future. It is because CDSs are one of the promising applications for human healthcare. In pharmaceutical market, the CDS is growing fast with approximate 10% annual increase. However, an important challenge in this area is the efficient delivery of drugs in the body using non-toxic nanocarriers. Most of the existing carrier materials show poor drug loading (usually less than 5 wt% of the transported drug versus the carrier material) and/or rapid release of the proportion of the drug that is simply adsorbed (or anchored) at the external surface of the nanocarrier. Many matrices have been tested so far, such as organic polymers, organic-inorganic hybridmaterials, bioactive glasses and ceramics. Among these, organic-inorganic hybrid material is promising for getting drugs to their targets in a controlled manner as it carries merits from both materials.

Our previous study in designing a composite microsphere formulation, composed of mesoporous silica spheres (MPS) and poly(D,L-lactide-co-glycolide) (PLGA), enables the controlled delivery of a prime-boost vaccine via the encapsulation of plasmid DNA (pDNA) and protein in different compartments. Based on this, DDSs that have a well controllable pore size and nanostructure can help understand and control their adsorption properties for drug molecules and the efficiency of cellular uptake. Zeolites having a pore size from 0.5 nm to 2 nm and more than 100 different pore structures is a promising candidate. We aim to produce uniform zeolite nanocrystals and nanostructures for the adsorption of drug molecules with sizes below and above 2 nm, respectively. An experimental approach is employed to fundamentally study the interaction of drug molecules with microporous zeolite matrices, and realise a controllable releasing of drug molecules to target sites. In addition to zeolites, MOFs are also used for CDSs. Their nontoxic nature, abundant structures, and potential for nanoparticle synthesis, coupled with unusually large loadings of different drugs, make them ideal candidates for a new valuable solution in the field of CDSs.

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