A panchromatic modification of the light absorption spectra of metal-organic frameworks.

The optical absorption of UiO-66-NH2 MOF was red-shifted using a diazo-coupling reaction. The modifications performed with naphthols and aniline yielded reddish samples, and the modifications with diphenylaniline yielded dark violet ones. The photocatalytic activity of these modified MOFs was assessed for methylene blue degradation, showing a good performance relative to traditional TiO2. The degradation performance was found to correlate with the red shift of the absorption edge. These findings suggest potential applications of these materials in photocatalysis and in dye sensitized solar cells.

Use of zeolitised coal fly ash for landfill leachate treatment: a pilot plant study.

Treatment of municipal solid waste (MSW) landfill leachate generally results in low percentages of nutrient removal due to the high concentration and accumulation of refractory compounds. For this reason, individual physical, chemical and biological processes have been used for the treatment of raw landfill leachate and sometimes for the mixture of domestic wastewater and landfill leachate. In this work, the possibility of treating landfill leachate was tested in a bench-scale pilot plant by a two-step method combining adsorption and coagulation-flocculation. Zeolite synthesized from coal fly ash, a by-product of coal-fired power stations, was used in this study both as a decantation aid reagent and as an adsorbent of COD and NH4-N. The coagulation-flocculation step was performed by the use of aluminium sulphate and a polyelectrolyte (ACTIPOL A-401). The leachate was collected directly from a storage unit of the organic fraction of MSW, before it was composted. For this reason the raw leachate was diluted before treatment. The sludge was recirculated to enhance the removal efficiency of nutrients as well as to optimize flocculant saving and to decrease sludge production. The results showed that it is possible to remove 43%, 53% and 82% of COD, NH4-N, and suspended solids, respectively. Therefore, this method may be an alternative for ammonium removal, as well as a suitable pre- or post-treatment step, in combination with other processes in order to meet regulatory limits.

Growth of gold nanoparticle arrays in TiO2 mesoporous matrixes.

An interconnected Au nanoparticle arrangement is obtained by electrodeposition from Au(III) soluble complexes within the pore system of block-copolymer templated mesoporous titania films. The resulting Au@TiO2 nanocomposites (5 nm Au particles, 5.5 nm amorphous titania walls) have the electrochemical behavior of a gold electrode of high surface area. The attenuation of Au surface plasmon due to -OH electroadsorption and the existence of mixed localized states in these Au@TiO2 nanocomposites are observed by in situ spectroelectrochemistry.

Anaerobic treatment of polyethylene glycol of different molecular weights.

Biodegradation of high molecular weight polyethylene glycol has been found difficult under aerobic conditions. The use of a chemical treatment prior to the aerobic one was necessary to remove high molecular weight of polyethylene glycol. Anaerobic treatment of polyethylene glycol may present an alternative to integrated chemical and biological treatment for the elimination of this compound. Anaerobic biodegradation of polyethylene glycol from 200 to 10,000 molecular weight was studied. It showed that, unlike aerobic treatment, the size of the molecule up to 10,000 does not affect the process efficiency. The critical retention time and the optimum retention time were estimated and ranged from 10 to 14 and from 16 to 19 days, respectively. Under these operational conditions percentage of removal ranged from 85 to 90%. Thus, anaerobic degradation of polyethylene glycol presents removal percentages and hydraulic retention times compounds similar to those of biodegradable tested at the same operational conditions.