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Valquíria Campos  - - - 
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Article 1 Read 0 Citations Synthesis of polycationic bentonite-ionene complexes and their benzene adsorption capacity Valquíria Campos, Celize Maia Tcacenco, Valquíria Campos, Ce... Published: 01 April 2015
Polímeros, doi: 10.1590/0104-1428.1727
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The purpose of this work was to structurally modify clays in order to incorporate water-insoluble molecules, such as petroleum hydrocarbons. The potential for ion exchange of quaternary ammonium salts was studied, which revealed their ability to interact with anions on the cationic surface, for environmental applications of the material. Ionenes, also known as polycations, have many potential uses in environmental applications. In this work, cationic aliphatic ammonium polyionenes, specifically 3,6-ionene and 3,6-dodecylionene, were prepared for incorporation into clay to form bentonite-ionene complexes. The intercalation of bentonite with ionene polymers resulted in an increase in the basal spacing of 3,6-dodecylionene from 1.5-3.5 nm. The higher d001 spacing of 3,6-dodecylionene samples than that of 3,6-ionene samples may be attributed to their longer tail length. The behavior of the TG/DTG curves and the activation energy values suggest that 3,6-dodecylionene (E = 174.85 kJ mol –1 ) is thermally more stable than 3,6 ionene (E = 115.52 kJ mol –1 ) complexes. The adsorption of benzene by 3,6-ionene and 3,6-dodecylionene was also investigated. The increase in benzene concentrations resulted in increased benzene adsorption by the sorbents tested in this work. The sorption capacity of benzene on ionene-modified bentonite was in the order of 3,6-dodecylionene > 3,6-ionene. Key words: 3,6-ionene; 3,6-dodecylionene; synthesis; adsorption of benzene
Article 2 Reads 3 Citations Assessment of the Removal Capacity, Tolerance, and Anatomical Adaptation of Different Plant Species to Benzene Contamina... V. Campos, L. S. Souto, T. A. M. Medeiros, S. P. Toledo, I. ... Published: 02 July 2014
Water, Air, & Soil Pollution, doi: 10.1007/s11270-014-2033-7
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The medium most directly affected by anthropic contamination is soil and, hence, groundwater (saturated and unsaturated zones). In the phytoremediation process, the direct absorption of soil contaminants through the roots is a surprising pollutant removal mechanism. Plants can act as a natural filter of shallow groundwater contamination, controlling and reducing the vertical percolation of contaminants into the soil, and after reaching the level of the water table, the roots can absorb contaminants dissolved in the water, thus reducing the size of the plume and protecting receptor sites (water supply wells, rivers, lakes) from possible contamination. In the first phase of the research, assays were performed to evaluate the tolerance of plant species to the direct injection of a benzene solution into the roots. Subsequent experiments involved direct absorption and spraying. The aim of this study was to evaluate the potential for tolerance and reaction to high levels of benzene. Three plant species were used, an herbaceous ornamental plant (Impatiens walleriana), a fern (Pteris vittata), and forage grass (Brachiaria brizantha). At the end of the study, the surface changes caused by VOCs (aerial structures) of benzene were evaluated, using an environmental scanning electron microscope (ESEM) to identify possible mechanisms of resistance of the plant to air pollution, i.e., hydrocarbon pollution. The plant material used here was young plant species selected for study. For the analysis by gas chromatography (GC), the plant material was separated into aerial (stem, leaves, and flowers) and underground parts (roots). A comparison of the benzene content in different parts of the plant indicated a higher concentration in the stem + leaves, followed by the roots, which is justified by its translocation inside the plant. P. vittata showed low uptake (5.88 %) mainly in the root and (I. walleriana showed benzene removal rates of approximately 18.7 % (injection into the soil) as a result of direct absorption through the roots. After the treatment was suspended, I. walleriana gradually reacted to the detoxification process by recovering its stem stiffness and normal color. B. brizantha showed intermediate behavior and did not react to the detoxification process.