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A unique 1D nanostructure of Pt@CeO 2 -BDC was prepared from Pt@CeBDC MOF. The Pt@CeO 2 -BDC was rich in oxygen vacancies (i.e., XPS O β /(O α + O β ) = 39.4%), and on the catalyst, the 2 nm Pt clusters were uniformly deposited on the 1D mesoporous polycrystalline CeO 2 . Toluene oxidation was conducted in a spectroscopic operando Raman-online FTIR reactor to elucidate the reaction mechanism and establish the structure-activity relationship. The reaction proceeds as follows: (I) adsorption of toluene as benzoate intermediates on Pt@CeO 2 -BDC at low temperature by reaction with surface peroxide species; (II) reaction activation and ring-opening involving lattice oxygen with a concomitant change in defect densities indicative of surface rearrangement; (III) complete oxidation to CO 2 and H 2 O by lattice oxygen and reoxidation of the reduced ceria with consumption of adsorbed oxygen species. The Pt clusters, which mainly exist as Pt 2+ with minor amounts of Pt 0 and Pt 4+ on the surface, facilitated the adsorption and reaction activation. The Pt-CeO 2 interface generates reduced ceria sites forming nearby adsorbed peroxide at low temperature that oxidize toluene into benzoate species by a Langmuir-Hinshelwood mechanism. As the reaction temperature increases, the role of lattice oxygen becomes important, producing CO 2 and H 2 O mainly by the Mars-van Krevelen mechanism.

A multilevel antimicrobial coating with "release-killing", "contact-killing" and "anti-adhesion" properties was prepared from polymer-encapsulated chlorine dioxide (ClO(2)), water-in-oil-in-water (w/o/w) double emulsion. A slow sustained release of gaseous ClO(2) at a rate sufficient to inhibit bacterial growth (approximately 1300 microg of ClO(2).g(-1).day(-1)) was demonstrated for a prolonged period of time (i.e., 28 days). Touch and infectious droplets triggered an increased release of the biocides at the sites of contamination, resulting in rapid disinfection. Zinc chloride (i.e., 30 ppm) was added to provide "contact-killing" properties, while bacterial adhesion was prevented by the Pluronic polymer used to encapsulate ClO(2). The new antimicrobial coating is effective against Gram positive and Gram negative bacteria, including Bacillus subtilis , Staphylococcus aureus , and Escherichia coli. A greater than 5 log (i.e., >or= 99.999%) reduction of viable bacteria was obtained at a short contact time of 10 min.

Cadmium pollution from the manufacture and disposal of NiCd batteries remains an important problem in developing countries. Among the available remedial technologies, adsorption is popular because of its low cost and simplicity. The mesoporous NH2-MCM-41 displays good adsorption capacities for cadmium and nickel ions. This work demonstrated for the first time the use of the competition between complexant and sorbentto create high adsorption selectivity. The selectivity was manipulated by the judicious use of a chelating agent, thus achieving on-demand 100% selectivity for either Cd2+ or Ni2+ adsorption. Single and binary components adsorption studies, carried out with different metals and EDTA concentrations, solution compositions and pH, showed that NH2-MCM-41 adsorbs only cadmium with a capacity of 0.56 mmol g(-1) from binary mixtures at [EDTA]/[M2+] = 0.5 and pH 5. The NH2-MCM-41 displays 100% selectivityfor nickel adsorption at [EDTA]/[M2+] = 0.5 and pH 2 with a measured adsorption capacity of 0.50 mmol g(-1). Pure Cd2+ and Ni2+ solutions were recovered by a simple acid wash, and the regenerated adsorbent could be reused without lost of performance (i.e., adsorption capacity and selectivity).

Two MCM-41 derived adsorbents have been tailor-made for the separation of silver and copper ions using the hard-soft, acid-base (HSAB) principle as the design guideline. NH2-MCM-41 containing "hard" Lewis base adsorption sites (i.e., RNH2) was prepared for the adsorption of the "hard" Lewis acid, Cu2+, and SH-MCM-41 with a grafted "soft" thiolpropyl base was prepared for the selective removal of Ag+, a "soft" Lewis acid. Single- and binary-component adsorption studies were conducted at different metal concentrations, solution compositions, and pH values. The experimental results showed that SH-MCM-41 has excellent affinity and capacity for silver adsorption and adsorbed only the silver ions with copper remaining in the solution. The selectivity was not affected by the metal concentration and composition, anion, and pH. Under similar experimental conditions, NH2-MCM-41 selectively adsorbed copper from the binary solution. The selectivity of NH2-MCM-41 remained for the copper at different pH values, although the adsorption capacity diminished at lower pH values. The type of anions used affected copper adsorption on NH2-MCM-41 with an increased copper uptake in the presence of the sulfate ions. A simple Freundlich adsorption model was sufficient to describe metal adsorption on SH-MCM-41 and NH2-MCM-41, and the LeVan and Vermeulen model was successfully used to predict the adsorption capacity and selectivity for binary-component adsorptions.

Gold-selective adsorbents were prepared from mesoporous MCM-41 silica by grafting organic amine groups (i.e., RNH2, R2NH, and R3N; R=propyl). NH2-MCM-41, NRH-MCM-41, and NR2-MCM-41 displayed strong affinity for gold and at 1 mmol/g loading adsorbed 0.40, 0.33, and 0.20 mmol/g of gold. Copper and nickel were not adsorbed on these adsorbents. Grafting surface chemical moieties introduces heterogeneity on an otherwise uniform MCM-41 pore surface and metal adsorption is best described by the Freundlich adsorption model. A series of binary adsorption equilibrium studies with NH2-MCM-41 containing 2.2 mmol RNH2/g shows that NH2-MCM-41 adsorbs only gold from solutions containing copper and nickel with an adsorption capacity of 0.6 mol of Au/mol of RNH2 (1.1 mmol of Au/g of NH2-MCM-41). Copper and nickel were not adsorbed by NH2-MCM-41 regardless of the solution concentration, composition, and pH (i.e., 2 to 4) in the presence of gold. The LeVan and Vermeulen adsorption model based on a single component Freundlich isotherm and corrected for the anion effect accurately predicted the binary adsorptions. The adsorbed gold was completely recovered by a simple acid wash and the recovered gold solution is 99% pure. The regenerated NH2-MCM-41 remained 100% selective for gold removal and exhibited the same adsorption capacity even after several uses.