Doktorska disertacija - Prirodno

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uticaja sastava, strukture, morfologije i mikrolegiranja u tehnologiji
p r e i š a v a n j a s i n t e t i k i h voda od štetnih sastojaka u jonskom i koloidnom stanju.
Abstract
Without new materials, there are no new technologies. Having in mind this fact, the main
idea was to obtain electrochemically active and structurally modified composites through
microalloying and certain metals hydroxides layering, starting from bentonite as
aluminosilicate precursor. The chemical composition and structural and surface
characteristics of bentonite were determined prior to its using for the synthesis of composites.
The composite were successfully obtained and denoted as KPM1, KPM2 and KPM3, with
prognosed electrochemical, ion-exchanging and adsorption properties, as very sensitive
structural and surface properties of materials. After the series of experiments, including
composites interaction with synthetic waters, the obtained results are presented, analyzed and
then systematized in the form of appropriate models of interactions. During composite KPM1
obtaining, at sintering temperature of 900°C, the infiltration of molten aluminum into the
pores of aluminosilicate matrix occurs. A small amount of metallic tin, resulting by reduction
of Sn 2+ , comes into contact with aluminum carrying out its microalloying which, together
with rapid cooling in a protective atmosphere of nitrogen, allows the electrochemical activity
of the composite KPM1. This procedure provides the primary structure of the composite. The
obtained experimental results confirmed the first hypothesis because structural modification
and metallization of bentonite matrix occurred, with specifically arranged structure,
consisting of amorphous regions in which crystalline phases are submerged. Such composite
structure is responsible for the electrochemical and other characteristics that are manifested
in contact with synthetic water containing manganese in the ionic state (Mn 2+ ) or colloidal
manganese (MnO 2). The modified porous composite KPM1 shows a particular
electrophoretic activity, electrochemical activity and efficiency of microgalvanic couples,
which confirm a second starting hypothesis. Manganese reduction to elemental state, wherein
it is in the form of metal deposited and retained in the porous structure of the composite,
leads to the secondary structure, responsible for the further electrochemical activity of the
composite is achieved. Experimental results showed that the colloidal MnO 2 was removed
from the synthetic water to a much lesser extent than the ionic form. This is explained with
the structure of colloidal micelles which carry a total negative charge and with higher
oxidation states of manganese (+4) in MnO 2. KPM2 composite was synthesized in order to
preferenly removes H 2S, its ionic fractions and colloidal sulfur from aqueous solutions.
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