DLS study of a phosphonate induced gypsum scale inhibition mechanism using indifferent nanodispersions as the standards for light scattering intensity comparisonстатья
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Дата последнего поиска статьи во внешних источниках: 10 апреля 2018 г.
Аннотация:The dynamic light scattering (DLS) special technique is used to study the bulk
supersaturated gypsum aqueous solutions during the induction period in 0.2 mol·dm–3 NaCl
at pH 9 and 25°C. It is based on the standard SiO2 nanoparticles (Ludox TM40) injection
into the supersaturated gypsum solution. These nanoparticles act as an internal indifferent
light scattering intensity reference and provide a semiquantitative measurement of a
relative gypsum particles content in a blank solution and in the system treated with aminotris(methylenephosphonic acid), ATMP. It is found that ATMP sufficiently reduces the
number of gypsum nuclei, spontaneously formed in the supersaturated solutions. In a
parallel way the chemical forms of antiscalant in the experimental systems have been
modeled. A tentative nonconventional mechanism of scale inhibition is proposed. It
assumes that the active crystal formation centers already exist in any analytical grade
aqueous solution in the form of solid nanoimpurities with a size ranging from one to
several hundred nm. The ATMP antiscalant competes with Ca2+ and
2 SO4 for these centers and blocks them. Therefore the number of gypsum growth centers diminishes
significantly. Thus the concentration of corresponding CaSO4·2H2O particles gets reduced
at least 10-fold. The collision rate of such particles decreases 100-fold. This explains both
induction time prolongation by ATMP and sub-stoichiometry of its efficacy.