Modification Of Structure And Properties
Modification of structure and properties
of organosilicone porous sorbents
by incorporation of complex metal ions
in the process of structure formation
Yu. N. Shewchenko
Ukrainian International Academy of Ingenious Ideas, Kyiv (Kiev), Ukraine,
Closed corporation «Environment Protection Enterprise KREOMA-PHARM», Kyiv, Ukraine
Methods used for the synthesis of globular porous sorbents with the aluminium, titanium or zirconium atoms incorporated in the structure isomorphously to silicon atoms were described earlier by I.B.Slinyakova and T.I.Denisova. The process is performed during the globule formation stage, due to the interaction of sodium methyl siliconate with tetrachlorides of the metals above in water-alkaline medium. The incorporation of metal ions which possess closed electron shell had provided new methods to control the porous structure depending on the number of incorporated metal ions, alkalinity of the polycondensation medium, and the temperature of sedimentation, maturation and washing of forming hydrogel.
The synthesis of metal complex polyorgano silicones (MCPOS, Yu.N.Shewchenko et al., 1985) which incorporate the 3d transition metals complexes was performed, the mechanisms of incorporation for both kinetically inert (Cr3+, Co3+) and kinetically labile (Cu2+, Ni2+, etc.) complexes was elucidated, and structural-sorption characteristics of the developed materials were studied. The particular feature of the new sorbents is the chemosorption ability for the selective binding of various adsorbates. These data, considered in line with the strong correlation between the dimensions of the pores formed and the radius of incorporated complex ions of 3d transition metals suggest unambiguously that the transition metal ions in MCPOS are located in the interglobular (intraporous) space.
In this publication we report the options for the modification of organosilicone porous sorbent provided by the incorporation of bi- or three-nuclear complexes, e.g.:
If the increase of relative fraction of Al3+ ions takes place (Al3+:Mz+> 1), the excessive ions become incorporated into the matrix structure , and do not affect the state of 3d metal ions which are involved in the new materials, while the presence of these ions influences the porous structure.
It is shown that Al3+ ions are located inside the globule, while complex ions of transition metals interact with the surface of the globules, which results in their location in the interglobular space. The 3d metal complexes incorporated into the matrix can possess octahedral (Cr3+, Co3+, Fe3+, Zn2+), tetragonally distorted bipyramid (Cu2+, Fe2+, Ni2+) or tetrahedral (Co2+, Fe2+, Cu2+) cis- or trans-structure with respect to double bridging links =Al(OH)2= located at the surface of globules.
This composition of the compounds and incorporated complexes is in a good agreement not only with the chemical analysis results and the data of IR and electron spectroscopy, but also with the ESR data measured using CPX-200 spectrophotometer at frequency 9.411GHz and room temperature for Fe3+ ion complexes, and at frequency 9.400GHz at 77K for cuprum complexes. In the ESR spectrum for PMS/Al3+/Fe3+ system, three signals were detected possessing g-factors of 2.0, 2.3 and 4.5, of which first two correspond to the Fe3+ ion in the octahedral environment and are observed for the ratio Al3+:Fe3+£2. With the increase of the Fe3+ ion contents in the system, sharp increase of the g=4.5 signal which corresponds to the Fe3+ ion in the tetrahedral environment takes place. In a similar way, the formation of bi- and three-nuclear complexes of Al3+ and Cu2+ can be detected: due to the different relaxation time, the signal with g0=2.15 (g||=2.348, g^=2.043) in the PMS/Al3+/Cu2+ system could be observed only in the region Al3+:Cu2+£1.6, where the formation of three-nuclear complexes Al3+ and Cu2+ takes place.
The presence of matrix structure explains the developed porous structure of the new adsorbents and their complete non-solubility in water, water/organic and known organic solvents. The adsorption-structural characteristics of the new adsorbents summarised below it was concluded that the introduction of Al3+ ions, in addition to the strong fixation of 3d metal ions, makes it possible to synthesise fine-porous sorbents possessing strongly developed specific surface, which results in their high adsorption potential and, consequently, high adsorption activity.
Adsorption-structural characteristics of the series of synthesised polyorgano silicones with incorporated bi- and three-nuclear complexes of aluminium and 3d transition metals.
Formula of prepared sorbent*
Nature of organic radical
Contents of metal ions,
mass%
Specific surface,Ssp, m2/g
Sorption volume of pores,
VS, cm3/g
Efficient pore radius,
reff, nm
Мz+
Al3+
{(RSiO1,5)375[AlO(OH)2]2Cu(H2O)2}
CH3–
0.25
0.21
230
0.52
2.1
{(RSiO1,5)268[AlO(OH)2]2Cu(NH3)2}
CH3–
0.35
0.30
240
0.50
1.9
{(RSiO1,5)250[AlO(OH)2]2Fe(acac)}
C6H5–
0.17
0.17
250
0.49
1.8
{(RSiO1,5)75[AlO1,5(H2O)][AlO(OH)2]2Cr (OH) (DMSO)3}
CH3–
0.96
1.50
320
0.40
1.6
{(RSiO1,5)166[AlO1,5(H2O)][AlO(OH)2]2
Zn(pn)}
CH2=CH–
0.48
0.60
360
0.35
1.5
{(RSiO1,5)125[AlO1,5(H2O)]0,5[AlO(OH)2]2
Ni(3,2,3 - tet)}
CH3–
0.67
0.92
300
0.42
1.6
{(RSiO1,5)107[AlO(OH)2]2 Fe(OH)(TiO)3}
C2H5–
0.61
0.59
290
0.37
1.3
{(RSiO1,5)125[AlO1,5(H2O)]0,7[AlO(OH)2]2
Co(en)OH(H2O)}
CH2=CH–
0.57
0.71
330
0.39
1.4
{(RSiO1,5)75[AlO1,5(H2O)]0,9[AlO(OH)2]2 Ni(cyclam)}
CH3–
1.07
1.42
340
0.40
1.5
{(RSiO1,5)107[AlO(OH)]2Co[NH2(CH2)2OH] [NH2(CH2)2O]}
CH3–
0.79
0.72
250
0.50
1.8
{(RSiO1,5)94[AlO(OH)]2Cr(OH)(NH2C2H5)3}
CH2=CH–
0.67
0.69
270
0.51
2.0
{(RSiO1,5)235[AlO1,5(H2O)]0,8[AlO(OH)2]2Co (2,3,2 – tet)}
C2H5–
0.30
0.39
240
0.47
1.7
{(RSiO1,5)145[AlO1,5(H2O)]0,9[AlO(OH)2]2Ni (TMC)}
C6H5–
0.31
0.40
300
0.42
1.5
{(RSiO1,5)107[AlO1,5(H2O)][AlO(OH)2]2
Zn (2,2,2 – tet)}
CH3–
0.86
1.07
320
0.42
1.6
*en – NH2(CH2)2NH2; pn – NH2(CH2)3NH2; n,m,l-tet – NH2(CH2)nNH(CH2)mNH(CH2)lNH2, with n,m,l – 2 or 3; acac – CH3COCH2COCH3; TiO – NH2CONH2; cyclam – ; TMC - .
The studies of bactericidal properties and adsorption capacity of these new sorbents with respect to the marker dyes of medium molecular biomolecules in comparison with these characteristics for the substance Cu‑MCPOS (USSR Authors’ certificate No.1460973, 1985) which is known to have the best properties in this substances class had shown that the organosilicone sorbents modified by bi- and three-nuclear complexes are capable for the adsorption of 4.0∙107 to 5.3∙107 cells of pathogenic microbes (Staphylococcus, Proteus, Pseudomonas aeruginosa, Shigellae, Salmonellae etc.) per 1cm2 of adsorbent specific area, which is 1.7 to 2.0 times larger than Cu‑MCPOS. Correspondingly, the period of total necrosis for microbes at the sorbent becomes 1.8 to 3.5 times lower (for Cu‑MCPOS this time is 360min).
New sorbents also possess maximum sorption capacity as measured in the aqueous solution with respect to the markers of medium molecular toxic metabolites: Congo red (molecular weight mv696, absorption band at λ=498nm) methyl red (mv291, λ=410nm) and Bengal pink (mv943, λ=502nm); the measurements were performed with SF‑6. The sorption capacity of the new sorbents with respect to these markers was 25 to 60μmol/g, i.e. 1.5 to 2.8 times higher than that for known MCPOS.
To summarise, the studies performed show the promising features of new biological sorbents modified by bi- and three-nuclear complexes of 3d transition metals and aluminium with respect to their medical application as selective enteral and application sorbents. Other practical applications of new sorbents also can be proposed, in particular related to their high chemosorption properties.
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