Optimized Rhodamine B labeled mesoporous silica nanoparticles as fluorescent scaffolds for the immobilization of photosensitizers: a theranostic platform for optical imaging and photodynamic therapy.

A highly efficient bifunctional mesoporous silica nanodevice coupling optical imaging with photodynamic therapy (PDT) was successfully prepared by using Rhodamine B as a contrast agent and verteporfin as a photosensitizer. The precise localization and high dispersion of the contrast agent in the nanoparticles is the key point to get higher fluorescence quantum yields with respect to the fluorophore in solution. To obtain this information photoluminescence spectroscopy coupled with fluorescence lifetime measurements was used, due to its high sensitivity. The bifunctional nanodevice showed good performances both in terms of quantum yield of the anchored Rhodamine B (Φ(RhB) = 0.55) and the singlet oxygen delivery efficiency for PDT applications.

Rose Bengal incorporated in mesostructured silica nanoparticles: structural characterization, theoretical modeling and singlet oxygen delivery.

Rose Bengal (RB), a xanthene dye, incorporated into mesostructured silica nanoparticles (MSNs) exhibits efficient singlet oxygen ((1)O2) generation when illuminated with 540 nm green light which is particularly promising for PDT applications. Several systems with different RB loadings were synthesized and fully characterized by means of spectroscopic techniques in combination with a computational study, to optimize the amount of RB in order to avoid the formation of aggregates that is detrimental for a high (1)O2 delivery.

UASB performance for bleached and unbleached kraft pulp synthetic wastewater treatment.

This paper presents the performance of two bench scale Upflow Anaerobic Sludge Blanket reactors (UASB) used for the treatment of synthetic substrates that simulate bleached and unbleached cellulose pulp plant wastewaters. The control reactor was fed with diluted black liquor and the treatment reactor with the same substrate plus a mixture of chlorinated organics. The total concentration of the chlorinated compounds was gradually increased from 2.5 mg l-1 to 15.0 mg l-1. The average COD removal efficiency during the last phase of the experiment was 81% in the control reactor and 76% in the treatment reactor. These results indicate the capability of UASB reactors to treat this kind of wastewater and the low impact of the chlorinated organics on COD removal efficiency. The minimum overall chlorinated organics removal efficiency was 71% and the maximum was 99.7%. The experiment indicates that under the conditions used in this research the presence of chlorinated organics does not negatively impact the treatment process.

Full scale fluidized bed anaerobic reactor for domestic wastewater treatment: performance, sludge production and biofilm.

This paper describes the performance, sludge production and biofilm characteristics of a full scale fluidized bed anaerobic reactor (32 m3) for domestic wastewater treatment. The reactor was operated with 10.5 m x h(-1) upflow velocity, 3.2 h hydraulic retention time, and recirculation ratio of 0.85 and it presented removal efficiencies of 71+/-8% of COD and 77+/-14% of TSS. During the apparent steady-state period, specific sludge production and sludge age in the reactor were (0.116+/-0.033) kgVSS. kgCOD(-1) and (12+/-5)d, respectively. Biofilm formed in the reactor presented two different patterns: one of them at the beginning of the colonization and the other of mature biofilm. These different colonization patterns are due to bed stratification in the reactor, caused by the difference in local-energy dissipation rates along the reactor's height, and density, shape, etc. of the bioparticles. The biofilm population is formed mainly of syntrophic consortia among sulfate reducing bacteria, methanogenic archaea such as Methanobacterium and Methanosaeta-like cells.

Influence of porosity and composition of supports on the methanogenic biofilm characteristics developed in a fixed bed anaerobic reactor.

This paper reports on the influence of the material porosity on the anaerobic biomass adhesion on four different inert matrices: polyurethane foam, PVC, refractory brick and special ceramic. The biofilm development was performed in a fixed-bed anaerobic reactor containing all the support materials and fed with a synthetic wastewater containing protein, lipids and carbohydrates. The data obtained from microscopic analysis and kinetic assays indicated that the material porosity has a crucial importance in the retention of the anaerobic biomass. The polyurethane foam particles and the special ceramic were found to present better retentive properties than the PVC and the refractory brick. The large specific surface area, directly related to material porosity, is fundamental to provide a large amount of attached biomass. However, different supports can provide specific conditions for the adherence of distinct microorganism types. The microbiological exams revealed a distinction in the support colonization. A predominance of methanogenic archaeas resembling Methanosaeta was observed both in the refractory brick and the special ceramic. Methanosarcina-like microorganisms were predominant in the PVC and the polyurethane foam matrices.

One-step synthesis of a highly active, mesoporous, titanium-containing silica by using bifunctional templating.

A highly active, three-dimensional, mesoporous titanosilica, TiTUD-1, with comparable properties to Ti-grafted mesoporous silica MCM-41, has been prepared in a one-step synthesis. A non-surfactant chemical, triethanolamine, was used as a template molecule. Triethanolamine easily forms complexes with titanium alkoxides, yielding titanatrane complexes, which together with free triethanolamine form meso-sized aggregates that template mesopores upon increasing the temperature of the synthesis mixture. Triethanolamine served as both mesopore template and ligand for the titanium complexes, which represent the majority of the catalytic-site precursors. The formation of the silica network and the titanium insertion were followed by a combination of diffuse reflectance UV/ Vis/NIR and FTIR spectroscopy. A titanium-rich phase was obtained on the mesopore surfaces during calcination, allowing for easy accessibility of the reactants to the catalytic sites. TiTUD-1 is about six times more active than framework-substituted Ti-MCM-41 and has similar activity to Ti-grafted MCM-41.