This article reports on an investigation into the ability of minced banana peel to extract lead and copper ions from water and the parameters involved in this process. The kinetics of copper and lead uptake reached equilibrium in 10 min and the extraction of metals ions was favorable above pH 3. The medium was characterized by FTIR, which showed absorption bands of carboxylic and amine groups at 1730 and 889 cm1, respectively. The adsorption isotherm fitted by Langmuir’s model showed maximum adsorption capacities of 0.33 and 0.20 mmol g−1 (or 20.97 and 41.44 mg g−1) for Cu(II) and Pb(II), respectively. Minced banana peel was applied in the preconcentration system and showed approximately 20-fold enrichment factor and the column was reused for 11 cycles without loss in the percentage of recovery. The proposed method was applied in the determination of Cu(II) and Pb(II) in a sample of raw river water and was validated by comparison with a standard reference material.

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Mesoporous silicas of the MSU-X type, made with nonionic polyethylenoxide-based (PEO) surfactants, were synthesized according to a two-step process that gives intermediary stable hybrid micelles. The influence of the various synthesis parameters, such as the silica concentration, the addition of a swelling agent (TMB:  trimethyl-1,3,5 benzene), the condensation catalyst (NaF), and the temperature of silica condensation, was systematically explored, especially their influence on the material pore size. Surprisingly, changing the silica over surfactant ratio does not modify the silica wall thickness but the other parameters have a strong effect on the final pore size. Considering the model of hybrid micelles that was previously reported (Boissière et al. Chem. Mater. 2001, 13, 3580), we explained the effect of the different parameters by a classical swelling effect of the hydrophobic micelle core for TMB, whereas the modulation of the hydrophilicity of the PEO chains (for temperature) or that of the silica oligomers (for NaF) describes correctly the variations observed. Finally, the cumulative effect of these parameters is demonstrated and we show that materials with narrow pore size distributions tuned between 2.5 and 5 nm can be obtained without changing the surfactant nor adding any swelling agent, by varying only the synthesis parameters.

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Ordered mesoporous highly luminescent SiO2 particles have been synthesized by spray pyrolysis from solutions containing tetraethylorthosilicate (TEOS) and either cetyltrimethylammonium bromide (CTAB) or the block copolymer Pluronic F-68 as structure-directing agents. Rhodamine B (RhB)-containing samples were prepared by using a simple wet impregnation method followed by the growing of a second silica shell in order to prevent leaching of the dye. The obtained materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder x-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-vis) and photoluminescence (PL). Powders with polydisperse spherical grains were obtained displaying an ordered hexagonal array of mesochannels. Luminescence results reveal that RhB molecules have been successfully encapsulated into the channels of mesoporous particles as monomeric species and that a well-defined silica coating hindered dye leaching.

This review sums up recent developments in the syntheses, anti-inflammatory activities, and structure–activity relationship (SAR) studies of pyrimidine derivatives.

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Recebido em 2/2/99; aceito em 16/6/99 THE ULTRASOUND EFFECT ON CHEMISTRY REACTIONS. Unusual chemical phenomenon associated with ultrasound is on account of cavitation effect. The ultrasound increase the rate and yield of chemical reaction on account of its ability to emulsify liquids. When the ultrasound is used in metallic catalyst reaction the activity of catalyst is increased because the ultrasound clean the surface of catalyst. Sonogels have a fine porosity and large specific surface improving different properties. This paper deals with ultrasound phenomenon and gives some examples of reactions and properties where this radiation takes an important role.