Mônica Regina Marques Palermo de Aguiar

Remoção de metais pesados de efluentes industriais por aluminossilicatos

This review had as aim the bibliography research for the use of aluminosilicates to remove heavy metals from wastewaters. Advanced studies based on parameters that have influence for removal of heavy metals as pH, metal concentration, effect of ligants and removal capacity of zeolites and clays, were reported. These studies demonstrate that aluminosilicates can be successfully used for the removal of heavy metals under the optimized conditions.

CHEMICAL MODIFICATION OF CROSS-LINKED RESIN BASED ON ACRYLONITRILE FOR ANCHORING METAL IONS

Abstract Network resin based on acrylonitrile has been chemically modified through different reactions to obtain different chelating groups. The beads of resin were synthesized by aqueous suspension copolymerization of acrylonitrile (AN) and divinylbenzene (DVB). The chemical modifications of these beads’ cyano groups were carried out by reaction with hydroxylamine, hydrazine and ethanolamine producing amidoxime, amidrazone and oxazoline groups, respectively. The copolymer and modified resins were characterized by apparent density, surface area, average pore diameter, elemental analysis (CHN), FTIR and optical and electronic microscopies. Qualitative experiments of adsorption were conducted to evaluate the resins (modified and unmodified) on fixing Hg(II), Cd(II), Cu(II), Zn(II), Cd(II), Co(II), Ni(II) and Pb(II) from aqueous solution using batch extractions. Based on the results obtained, it was concluded that it is possible to modify chemically a resin containing cyano groups by different routes and to use these resins as a very low cost effective sorbent for metal ions.

Characterization of natural Brazilian clays and their utilization as catalysts in the coiodination of alkenes with water and alcohols

As argilas naturais brasileiras F-101, F-117 e caulim foram caracterizadas atraves de analises quimica e textural, difracao de raios X e RMN no estado solido de 27Al e 29Si. A argila F-101 e uma esmectita, a F-117 e uma estrutura interestratificada contendo esmectita, caulinita e mica como argilominerais. O caulim e essencialmente uma caulinita. As argilas F-101 e F-117 sao catalisadores mais eficientes para a coiodacao de estireno e ciclo-hexeno com agua e alcoois para produzir iodoidrinas e b-iodo-eteres, respectivamente, comparadas ao caulim e a argila montmorilonita K-10.

Synthesis of crosslinked resin based on methacrylamide, styrene and divinylbenzene obtained from polymerization in aqueous suspension

Abstract A series of porous copolymer beads based on methacrylamide (MA), styrene and divinylbenzene (DVB) was prepared by aqueous suspension polymerization in the presence of diluents to act as precipitants. As MA is totally soluble into aqueous phase, the use of two types of phase transfer agent was investigated, namely: TritonX-100TM [polyoxyethylene-(10)-isooctylphenyl-ether] and tetrabutylammonium perchlorate. The effect of the diluents on the surface appearance and the porous structure of copolymer beads was studied. Suitable particle stabilisation was achieved by using a combination of two suspension agents, namely: gelatin and 2-hydroxy-ethyl-cellulose. The network resins were characterized by optical and scanning electron microscopy, IR spectroscopy, elemental analysis (CHN), apparent density, swelling in different solvents and specific area by BET method. It was observed that the MA incorporation was more effective when TritonTM was employed as phase transfer agent.

Modification of porous copolymers network based on acrylonitrile

SummaryThe preparation of a chelating ion-exchange network based on acrylonitrile was carried out by chemical modification with hydroxylamine. The beads of resin were synthesized by aqueous suspension copolymerization of acrylonitrile (AN), styrene (STY) and divinylbenzene (DVB). The influence of diluent used in the suspension polymerization on the structure of the resulting copolymers was evaluated. The diluents employed were heptane (HEP), toluene (TOL) and anisole (ANI). It was found that the AN incorporation into copolymer structure was dependent on the diluent used. Conversion of nitrile groups into the amidoxime was conducted by treatment with hydroxylamine under alkaline solution. The resins were characterized by apparent density, surface area, average pore diameter, elemental analysis (CHN), FTIR and optical microscopy. Based on the results obtained, it was possible to control the porosity by diluent employed in the synthesis and to modify chemically a resin containing nitrile groups by hydroxylamine reaction.

Microscopic analysis of porosity of 2-vinylpyridine copolymer networks. 1. Influence of diluent

The porous structure of copolymer networks based on 2-vinylpyridine, styrene and divinylbenzene at varied proportions prepared by suspension polymerization was varied by using different kinds of porogen agent, namely toluene, n-heptane, ethyl acetate. The materials were characterized by determination of surface area, average pore diameter and pore volume by BET/BJH, apparent density, elemental analysis (CHN) and swelling degree. Their morphologic characteristics were evaluated by microscopic analyses and correlations among porous structures and reaction parameters were found. It was noted that all synthesized resins have presented narrow particle size distributions; their porosities and visual appearances were dependent on the type and dilution of solvent employed in their syntheses.

Caracterização de polimorfismo em fármacos por ressonância magnética nuclear no estado sólido

This review aims to present some features about solid state NMR and its application in the field of pharmaceutical chemistry, for the characterization of polymorphism of pharmaceutical molecules.

Microscopic characterization of porosity and chemical modification of acrylonitrile copolymer networks

The effects of different kinds of diluents (porogen agents), namely, toluene (TOL), n-heptane (HEP), anisole (ANI) and mixtures of them, on the porous structure of copolymer networks based on acrylonitrile (AN) and divinylbenzene (DVB) prepared by suspension polymerization were analyzed by microscopic analyses [both optical (OM) and scanning electron microscopies (SEM)]. It was noted that all synthesized resins have presented dispersed particles size, and that their porosities were dependent on the type of diluent employed in their syntheses. The amidoximation of cyano groups of AN-DVB copolymers employing two kinds of treatment with hydroxylamine under alkaline solution was also studied.

A new environmental friendly clay catalyst for one-pot coiodination and epoxidation of alkenes

The commercial Brazilian clay Bentonit Brasgel™ was characterized by chemical and textural analyses, XRD, and 27Al and 29Si MAS-NMR, that indicated the presence of a-quartz and smectite as clay-minerals. This natural clay proved to be an efficient catalyst for the conversion of alkenes into epoxides by the reaction with iodine/water followed by in situ addition of KOH in hexane (80-91 % yield). Similar results were obtained with Bentonit Brasgel™ intercalated with Ag(I).

Green Alkoxyiodination of Cyclohexene Mediated by Natural Clay

Abstract The reaction of cyclohexene with iodine and alcohols (ethanol, isopropanol, and t‐butanol) at room temperature is effectively mediated by clays to produce the corresponding trans‐β‐alkoxy‐iodocyclohexane.