Comparison of Ten Metal-Doped LaFeO Samples on Photocatalytic Degradation of Antibiotics in Water under Visible Light: Role of Surface Area and Aqueous Phosphate Ions.

Doping semiconducting oxides, such as LaFeO (LF), with metallic elements is a good strategy to improve the performance of photocatalysts. In this study, LF and ten different nanopowders metal-doped at the La or Fe site of LaFeO were evaluated in the photocatalytic degradation of ciprofloxacin (CP) and oxytetracycline (OTC). The following metals were used in the doping (mol%) process of LF: Pd 3% and 5%; Cu 10%; Mg 5%, 10%, and 20%; Ga 10%; Y 10% and 20%; and Sr 20%.

Applications of Heterogeneous Photocatalysis to the Degradation of Oxytetracycline in Water: A Review.

Photocatalytic processes are being studied extensively as potential advanced wastewater treatments for the removal of pharmaceuticals, pesticides and other recalcitrant micropollutants from the effluents of conventional wastewater treatment plants (WWTPs). Oxytetracycline (OTC) is a widespread antibiotic which is frequently detected in surface water bodies as a recalcitrant and persistent micropollutant. This review provides an update on advances in heterogeneous photocatalysis for the degradation of OTC in water under UV light, sunlight and visible-light irradiation.

Fast photocatalytic degradation of pharmaceutical micropollutants and ecotoxicological effects.

Aqueous solutions of ciprofloxacin (CP) and ibuprofen (IBP) in the presence of LaFeO photocatalyst, of HO, and of both LaFeO and HO were irradiated under visible light. The degradation rate in the presence of both LaFeO and HO after 5 h irradiation was more than 90 % for CP and 40 % for IBP, much higher than that with only HO under visible light. For the sake of comparison, the experiments were also carried out in the dark, and both CP and IBP were not significantly converted.

Quantum mechanics calculations, basicity and crystal structure: the route to transition metal complexes of azahelicenes.

Quantum mechanics density functional calculations provided gas-phase electron distributions and proton affinities for several mono- and diaza[5]helicenes; computational results, together with experimental data concerning crystal structures and propensity to methylation of the nitrogen atom(s), provide a basis for designing azahelicene complexes with transition metal ions.

Photophysical properties of N-alkylated azahelicene derivatives as DNA intercalators: counterion effects.

In this work, three compounds having the same organic moiety (N-methyl-5-azahelicenium salts) but different counterions (I-, NO3- and COOCF3-) have been investigated in buffered aqueous solutions and in the presence of DNA to give information on the counterion effects on the binding. In particular, the absorption spectra, fluorescence quantum yields and fluorescence lifetimes in aqueous solution for free organic molecules have been determined by steady-state and time-resolved spectrofluorimetric measurements. The obtained values are compared with those of the chromophores in the presence of increasing concentrations of DNA.

Immobilization of organic pollutants in cement pastes admixed with organophilic materials.

The results of 2-chloroaniline (2-CA) immobilization experiments in cement matrices, using an organophilic clay modified with phenolic resins as pre-sorbent, are shown. The 2-CA suspended in water was kept in contact with the organoclay for 24 h, and the slurry obtained was then admixed with ordinary Portland cement (OPC) without additional water, to obtain a firm solid waste. Six cement-clay pastes were prepared with the same water-to-cement ratio (0.

Use of admixtures in organic-contaminated cement-clay pastes.

In this work microstructure, porosity and hydration degree of cement-based solidified/stabilized wasteforms were studied before assessing their leaching behaviour. 2-Chloroaniline was chosen as a model liquid organic pollutant and included into cement pastes, which were also modified with different admixtures for concrete: a superplasticizer based on acrylic-modified polymer, a synthetic rubber latex and a waterproofing agent. An organoclay, modified with an ammonium quaternary salt (benzyl-dimethyl-tallowammonium, BDMTA), was added to the pastes as pre-sorbent agent of the organic matter.

Cement-clay pastes for stabilization/solidification of 2-chloroaniline.

Immobilization of a model liquid organic pollutant, i.e. the 2-chloroaniline (2-CA), into a cement matrix using organoclays as pre-sorbent agents was investigated.