Nanosized silica modified with carboxylic acid as support for controlled release of herbicides.

Hexagonal mesoporous silica modified with carboxylic acid (SiAc) has been obtained by reaction between chloroacetic acid and 3-aminopropyltrimethoxysilane, which was immobilized on porous material by a sol-gel process in the presence of an n-dodecylamine template. SiAc was characterized by TG, FT-IR, (29)Si NMR, (13)C NMR, SEM, surface charge density, surface area and porous diameter, which proved that the carboxylic group was chemically bonded to an inorganic structure, and the material presented a nanometric structure with spheres <50 nm and porous diameter of 10 nm. Herbicides 2,4-D and picloram were anchored on SiAc porous gel to produce the materials named SiD and SiPi, respectively.

Effect of thermal dehydration and rehydration on Na-magadiite structure.

The effect caused by dehydration and rehydration of the synthetic Na-magadiite was investigated by TGA, XRD, SEM, and (29)Si NMR. Thermal analysis of Na-magadiite presented two well-defined loss mass stages between 20 and 150 degrees C and another between 270 and 310 degrees C, both related to the removal of interlayer water. The swelling behavior of Na-magadiite was studied by thermal dehydration data obtained at 150 and 300 degrees C, and respective rehydration by water addition.

Hexagonal mesoporous silica modified with copper phthalocyanine as a photocatalyst for pesticide 2,4-dichlorophenoxiacetic acid degradation.

A new mesoporous catalyst was prepared by the reaction between 3-aminopropyltrimethoxisylane and Cu(II)-hexadecafluorophthalocyanine, followed by co-condensation of tetraethylorthosilicate around a micelle formed by n-dodecylamine. The surfactant was removed from the pores by continuous extraction with ethanol, giving the Si-CuF16Pc catalyst. This catalyst was characterized by SEM, FTIR, TGA, 29Si NMR, N2 adsorption and X-ray diffraction.