Aqueous suspensions of highly disperse silica and germania/silica

被引:19
作者
Gun'ko, VM
Zarko, VI
Turov, VV
Leboda, R
Chibowski, E
Gun'ko, VV
机构
[1] Inst Surface Chem, UA-252022 Kiev, Ukraine
[2] Marie Curie Sklodowska Univ, Fac Chem, Dept Phys Chem, PL-20031 Lublin, Poland
[3] Natl Tech Univ Ukraine, UA-252056 Kiev, Ukraine
[4] Marie Curie Sklodowska Univ, Fac Chem, Dept Chem Phys, PL-20031 Lublin, Poland
关键词
CVD-germania/silica; electrophoretic mobility; zeta potential; particle size distribution; H-1; NMR; interface modeling;
D O I
10.1006/jcis.1998.5626
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Highly disperse germania has been synthesized on the surface of fumed silica by the chemical vapor deposition (CVD) technique. Aqueous suspensions both of unmodified fumed silica and of the obtained germania/silica (GS) samples have been studied by elec trophoresis, photon correlation spectroscopy, nuclear magnetic resonance (H-1 NMR), and quantum chemical semiempirical AM1-SM1 methods. For suspensions of GS samples, electrophoretic mobility, isoelectric point (IEP), particle size distribution, average effective diameter (D-ef), and free energy changes (Delta G) of interfacial water were found to depend nonlinearly on the concentration of germania (C-GeO2), At small concentrations, the structure of the synthesized germania is clustered rather than layered. For the last samples, maximum reduction of the free energy for interfacial water and larger values of IEP and D-ef in comparison with GS at high C-GeO2 or unmodified silica have been observed. In suspensions, the particle size distributions for silica and GS are uni-, bi-, and trimodal and depend on pH and C-GeO2. Values of polydispersity (P) are very rarely smaller than 0.05 and are usually between 0.25 and 0.70, which points to the wide size distribution. The solvation energy of the charged and uncharged GS clusters calculated by AM1-SM1 method decreases with increasing germania concentration. (C) 1998 Academic Press.
引用
收藏
页码:106 / 120
页数:15
相关论文
共 51 条
[1]  
ARMITAGE DA, 1987, ORGANOMETAL CHEM, V15, P84
[2]   REGULAR RING DYNAMICS IN AX2 TETRAHEDRAL GLASSES [J].
BARRIO, RA ;
GALEENER, FL ;
MARTINEZ, E ;
ELLIOTT, RJ .
PHYSICAL REVIEW B, 1993, 48 (21) :15672-15689
[3]   SURFACE INTERACTIONS OF DIMETHYLSILOXY GROUP-MODIFIED FUMED SILICA [J].
BARTHEL, H .
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS, 1995, 101 (2-3) :217-226
[4]  
BARTHEL H, 1996, ORGANOSILICON CHEM, V2, P761
[5]  
CHEN SH, 1981, SCATTERING TECHNIQUE
[6]  
Chuiko A.A., 1993, SILICAS MED BIOL
[7]   PROTON AFFINITY DISTRIBUTIONS OF TIO2-SIO2 AND ZRO2-SIO2 MIXED OXIDES AND THEIR RELATIONSHIP TO CATALYST ACTIVITIES FOR 1-BUTENE ISOMERIZATION [J].
CONTESCU, C ;
POPA, VT ;
MILLER, JB ;
KO, EI ;
SCHWARZ, JA .
JOURNAL OF CATALYSIS, 1995, 157 (01) :244-258
[8]   GENERAL PARAMETERIZED SCF MODEL FOR FREE-ENERGIES OF SOLVATION IN AQUEOUS-SOLUTION [J].
CRAMER, CJ ;
TRUHLAR, DG .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1991, 113 (22) :8305-8311
[9]  
Dahneke BE, 1983, MEASUREMENTS SUSPEND
[10]   A MOLECULAR-DYNAMICS STUDY OF THE VIBRATIONAL PROPERTIES OF SILICA GLASS [J].
DELLAVALLE, RG ;
VENUTI, E .
CHEMICAL PHYSICS, 1994, 179 (03) :411-419