Designed formulation based on α-tocopherol anchored on chitosan microspheres for pH-controlled gastrointestinal controlled release.

Chitosan microspheres were prepared and vitamin E (α-tocopherol) was anchored onto the polymer. The amount of α-tocopherol entrapped onto a gram of the microspheres based system was 13.4±0.

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.

Adsorption and preconcentration of divalent metal ions in fossil fuels and biofuels: gasoline, diesel, biodiesel, diesel-like and ethanol by using chitosan microspheres and thermodynamic approach.

Biodiesel and diesel-like have been obtained from soybean oil by transesterification and thermal cracking process, respectively. These biofuels were characterized as according to ANP standards by using specific ASTM methods. Ethanol, gasoline, and diesel were purchased from a gas station.

Photocatalytic decouloration of malachite green dye by application of TiO2 nanotubes.

The nanotubes of titania were synthesized in a hydrothermal system and characterized by scanning electronic microscopy (SEM), FT-IR, FT-Raman, and surface charge density by surface area analyzer. These nanomaterials were applied to photocatalyse malachite green dye degradation. Photodegradation capacity of TiO(2) nanotubes was compared to TiO(2) anatase photoactivity.

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.

Buffer capacity of humic acid: thermodynamic approach.

Commercial humic acid was dialyzed and characterized by infrared, UV/vis spectroscopy, (13)C NMR spectrometry, thermogravimetry, and elemental analysis. The dialyzed humic acid was titrated with HNO(3) and NaOH in order to obtain the buffer capacity value (beta). The humic acid presented buffer behavior by base and acid addition, and moreover, an excellent buffer capacity by addition of NaOH.

Modification of silica gel by attachment of 2-mercaptobenzimidazole for use in removing Hg(II) from aqueous media: a thermodynamic approach.

The compound 2-mercaptobenzimidazole (MBI) was attached onto a silica gel surface by homogeneous and heterogeneous routes. Both silica modification methodologies resulted in similar products, named SiM(hom) and SiM(het), respectively. These materials were characterized by surface area, infrared, thermogravimetry, and 13C and 29Si NMR spectroscopy.

Studies on copper(II)- and zinc(II)-mixed ligand complexes of humic acid.

Interactions between humic acid (HA), extracted from Brazilian peat soil, and cations of copper(II) and zinc(II) have been examined by infrared spectroscopy, and electrochemical and thermogravimetric analyses. Spectral studies revealed that the interaction with metals occurred mainly at the carboxylic acid groups of HA. The stability constants of HA complexes formed with Cu(2+) and Zn(2+) were found, by square wave voltammetry and application of the Lingane model, to be 8.

Thermodynamic studies of the interaction at the solid/liquid interface between metal ions and cellulose modified with ethylenediamine.

The chelate molecule, ethylenediamine, has been incorporated onto the surface of cellulose by sequential reaction of cellulose fibres with phosphorous oxychloride followed by the chelating agent. The modified material (CelNN) retained its fibrous nature and was shown to be efficient at adsorbing divalent metal cations from water by complexation. Adsorption isotherms were determined for suspensions of CelNN in metal ion solutions of different concentrations, and the data were adjusted to fit the modified Langmuir equation.

The interaction at the solid/liquid interface of 2,4-dichlorophenoxyacetic acid with silica modified by reaction with ammonia gas.

A method for the attachment of ammonia to modified silica gel has been developed. In the first step, tetraethylorthosilicate and (3-glycidoxypropyl)trimethoxysilane were co-condensed in the presence of n-dodecylamine, a neutral surfactant template, to produce a modified mesoporous silica. The epoxy group incorporated into the mesoporous silica was opened by ammonia gas thus introducing amine chelate groups covalently bound to the inorganic surface.

Adsorption and thermochemical data of divalent cations onto silica gel surface modified with humic acid at solid/liquid interface.

Humic acid immobilized onto silica gel surface was studied by the calorimetric titration of divalent cations in aqueous solution. The adsorption isotherms were obtained by the batchwise method and were fitted to a modified Langmuir equation. The maximum number of moles per gram of the material gave: 10.

Comparative adsorption studies of indigo carmine dye on chitin and chitosan.

The adsorption of indigo carmine dye onto chitin and chitosan from aqueous solutions was followed in a batch system. The ability of these materials to adsorb indigo carmine dye from aqueous solution was followed through a series of adsorption isotherms adjusted to a modified Langmuir equation. The maximum number of moles adsorbed was 1.

Calorimetric studies of the association of chitin and chitosan with sodium dodecyl sulfate.

The interaction of hydrophobic chitin and chitosan with sodium dodecyl sulfate (SDS) has been studied by titration calorimetry at 298.15K. The nature of interaction of the surfactant and biopolymers was followed by enthalpy interaction profiles.

Adsorption, separation, and thermochemical data on the herbicide picloram anchored on silica gel and its cation interaction behavior.

The herbicide 4-amino-3,5,6-trichloropicolinic acid (picloram), chemically anchored on silica gel surface (SiPi), has been used for divalent cation M(2+) (Cu, Ni, Zn, and Cd) adsorption from aqueous solutions at room temperature. The series of adsorption isotherms were adjusted to a modified Langmuir equation from data obtained by suspending the solid with MCl(2) solutions, which gave the maximum number of moles adsorbed as 9.27, 7.

A toxicity view of the pesticide picloram when immobilized onto a silica gel surface.

The pesticide picloram (4-amino-3,5,6-trichloropicolinic acid) was anchored onto silica gel to yield a new surface. Isothermal microcalorimetry was applied to study the toxic effects caused to microbial activity of a typical Brazilian agricultural soil by application of free and immobilized picloram. The activity of the microorganisms in 1.

The Pesticide 3-(3,4-Dichlorophenyl)-1,1-dimethylurea (Diuron) Immobilized on Silica Gel Surface.

A route for 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron) immobilization on silica gel was established after reacting at the first stage the precursor silylant agent 3-trimethoxysilylpropylamine to the support. The pesticide was covalently bonded to available amine groups of the precursor, giving 1.03 mmol of amine per gram of silica.