Frank Leung-Yuk Lam

Copper/MCM-41 as catalyst for photochemically enhanced oxidation of phenol by hydrogen peroxide

Heterogeneous copper catalyst was developed using the mesoporous molecular sieve MCM-41 as the catalyst support. Copper was impregnated onto the support. Catalysts with different copper loadings were obtained. The performance of the developed catalysts was evaluated in photochemically enhanced oxidation of phenol using hydrogen peroxide as the oxidant. The catalyst was found to significantly increase the oxidation rate and enhance the removal level of phenol with UV light present. The effects of copper loading on the catalyst, photo (UV), H2O2 concentration, and catalyst dosage on the photo-oxidation of phenol were studied

A new system design for the preparation of copper/activated carbon catalyst by metal-organic chemical vapor deposition method

Abstract A metal-organic chemical vapor deposition (MOCVD) technique was used to prepare heterogeneous metallic catalyst supported on activated carbon. A new system design was built to achieve higher metal loading within a shorter preparation time. In the optimization of system parameters, higher metal loading can be achieved by using longer deposition time, optimum carrier gas flow rate, higher operating temperature of either evaporation zone or a deposition zone or a smaller amount of porous support. Several techniques were carried out to characterize the catalyst such as physisorption, X-ray diffraction, inductively coupled plasma—optical emission spectroscopy and scanning electronic microscopy assisted with the Energy dispersive X-ray spectroscopy (SEM-EDX). It was found that the BET specific surface area and total adsorption volume of the prepared catalysts were reduced after metal deposition, due to the formation of the deposited copper onto the porous media both externally and internally. The morphology of the cylindrical Cu/AC was analyzed by SEM-EDX. The results show that the metal was deposited with a reasonably uniform distribution onto the inner part of the porous support.

Development of a novel photocatalyst for the advanced antibiotic oxidation of wastewater

Background Between 2000 and 2010, the consumption of antibiotics in 71 countries increased by 36% [1]. The rise of antibiotic consumption is expected to continue, considering the potential genetic mutation of super bacteria. Most antibiotics cannot be fully metabolised by the human body [2] and are excreted into the environment via wastewater effluents. Typical biological treatment processes, which have been used for several decades in wastewater treatment, normally require a long processing time for the development of new cells in biomass. More importantly, antibiotics are not easily degraded by bacteria, so the removal of antibiotics from wastewater is of only low efficiency. Researchers have therefore recently attempted an advanced oxidation processes (AOP) for the treatment of antibiotics in wastewater. In addition to the widely used photocatalyst TiO2, bismuth oxybromide, BiOBr, has received much attention in recent years for its generation of hydroxyl radicals, due to its high stability and low band gaps. This study aims to modify BiOBr for enhancing the oxidation of antibiotics. Success in this study will bring a new insight to the understanding of catalysis.

Giant enhancement of the upper critical field and fluctuations above the bulk Tc in superconducting ultrathin lead nanowire arrays.

We have produced ultrathin lead (Pb) nanowires in the 6 nm pores of SBA-15 mesoporous silica substrates by chemical vapor deposition. The nanowires form regular and dense arrays. We demonstrate that bulk Pb (a type-I superconductor below Tc = 7.2 K with a critical field of 800 Oe) can be tailored by nanostructuring to become a type-II superconductor with an upper critical field (Hc2) exceeding 15 T and signs of Cooper pairing 3-4 K above the bulk Tc. The material undergoes a crossover from a one-dimensional fluctuating superconducting state at high temperatures to three-dimensional long-range-ordered superconductivity in the low-temperature regime. We show with our data in an impressive way that superconductivity in elemental metals can be greatly enhanced by nanostructuring.

Factors associated with the uptake of seasonal influenza vaccination in adults: a systematic review.

Studies on different populations have shown that a variety of factors influence attitudes and decision in the general population on vaccine uptake. This study explores factors associated with the uptake of influenza vaccination among adults. A systematic literature review was performed on literature searched in databases EMBASE, MEDLINE, Cochrane Library and Electronic Theses Online Service up until November 2013. A critical appraisal framework was designed to assess the methodological quality of the studies. Twenty-three articles met the inclusion criteria and were selected for outcome analysis and 21 were quantitative observational studies. Advancement in age (OR 1.06-23.7) and having chronic diseases (OR 1.38-13.7) were strongly indicative of vaccine uptake. Perceptions on vaccine efficacy (OR 2.7-10.55) and vaccine safety and adverse events (OR 10.5) were more influential than the level of knowledge on influenza and its vaccination. Advice from doctors/health professionals/family and/or close friends and free vaccination were also key factors in association with uptake of vaccination. This review highlighted the finding that perception on vaccine efficacy, perception on vaccine safety and adverse events, advice from doctors/health professionals/family/close friends and free vaccination are changeable factors that are strongly associated with influenza vaccination in adults aged 18-64.

Heterogeneously catalyzed strategies for the deconstruction of high density polyethylene: plastic waste valorisation to fuels

The plastic industry generates enormous quantities of plastics at projected rates (both production and consumption) which can significantly threaten our environment in terms of plastic waste generation. High density polyethylene (HDPE) is one of the main fractions of municipal solid waste which has a remarkable potential to be valorised into fuels (e.g. bio-oils). Catalytic degradation is an innovative alternative process to transform plastic waste into such value added products. This mini review was aimed to discuss the most relevant and recent catalysts developed for the catalytic degradation of HDPE including metal oxides, sulphated metal oxides, zeolites, nanostructured zeolites, molecular sieves, fluid catalytic cracking (FCC) catalysts, metal carbonates and mesoporous materials for the production of chemicals and fuels (e.g. diesel and gasolines). Activities and selectivities as well as important effects of additives, particle size, catalyst to polymer ratios and also recent approaches for waste management will be discussed.

Formation of an ink-bottle-like pore structure in SBA-15 by MOCVD.

Metallorganic chemical vapor deposition is used as a simple pore-modifying method to fine tune the pore-opening size of SBA-15 materials without significant loss in pore volume and surface area.

Cellulose as an Efficient Matrix for Lipase and Transaminase Immobilization

Immobilization of enzymes is important to improve their stability and to facilitate their recyclability, aiming to make biocatalytic processes more efficient. One of the important aspects is the utilization of cheap, abundant, and environmentally friendly carriers for enzyme immobilization. Here we report the use of functionalized cellulose for lipase and transaminase immobilization. High immobilization efficiencies (up to 90%) could be achieved for the transaminase from Vibrio fluvialis. For immobilized lipase CAL-B as well as the transaminase, good conversions and recyclability could be demonstrated in kinetic resolutions to afford chiral alcohols or amines. Moreover, such application of the immobilized transaminase enabled very high conversions in a continuous-flow process in the asymmetric synthesis of (S)-phenylethylamine (80% conversion, >99% ee).

Continuous Flow Preparation of Iron Oxide Nanoparticles Supported on Porous Silicates

A simple, innovative, and efficient continuous flow methodology for the direct preparation of supported nanoparticles on porous materials by using metal precursor solution flowing through heated packed‐bed reactors containing the support material has been developed. The effects of the flow rate of the precursor solution, temperature, and nature of the support material and metal loading have been investigated. Results indicated that optimum conditions comprised short residence times (with typical flow rates of 0.5 mL min−1 and below) under mild heating (100 °C) to achieve optimum materials in terms of nanoparticle size and structure and catalytic activity. The support was found to have a remarkable effect on both loading and distribution and agglomeration of nanoparticles in the system, with a previously reported Fe/Al synergy also observed in the prepared nanomaterials, which led to optimum results.

The Role of the Coherence Length for the Establishment of Global Phase Coherence in Arrays of Ultra-thin Superconducting Nanowires

We have fabricated 5 nm ultra-thin NbN nanowires that form a dense and regular array in the linear channels of mesoporous SBA-15 silica substrates. Bulk NbN is a well-known classical superconductor with T c of 16 K. We show that, by being incorporated into this nanostructure, the composite material exhibits typical quasi-one-dimensional characteristics. We compare the superconducting properties with those of superconducting Pb nanowires of the same dimensionality in identical configuration within the linear SBA-15 pores. While Pb nanowire arrays show a pronounced crossover from 1D superconductivity at high temperatures to a 3D bulk superconducting state in the low-temperature regime with true zero resistance triggered by transversal Josephson interaction, this transition appears to be completely absent in the NbN nanowire array. The small coherence length in NbN, which strongly suppresses the Josephson coupling is discussed as the origin of this difference.