540
O. Lavrynenko et al.
impurities free magnetite and, simultaneously, such nanoparticles showed semiconducting behavior [9]. Moreover, the combination of plasmonic properties alongside
magnetic was notified for magnetite particles preliminarily doped by silver [10].
The interaction of aurum (III) aquaforms with iron oxyhydroxides in natural
systems may occur via adsorption mechanisms [11] and accompanied by donating
electron that supplied reduction of dissolved aurum complexes to the metallic state
during the steps of oxidation of the sulfide or oxide minerals [12]. Ferrous cations
of magnetite or Green Rust structures can reduce aurum concentration and precipitate gold on the oxidized mineral surface. By the second way the interaction of
ferrous cations, as a product of the dissolution of corresponding minerals with aurumcontaining complexes takes place in the subsurface waters and water solutions. Such
kind of reactions leads to the simultaneous precipitation of gold particles and disperse
iron oxides. Hence, the ferrous-containing minerals and mineraloids (colloid particles) play a big role in supergene systems for the secondary silver and gold deposits
formation [13] and take place in biogeochemical cycles of iron, aurum, and argentum,
as well [14]. As a rule, gold species adsorption on the surface of iron oxyhydroxides
accompanied by the formation of varies inner-sphere surface complexes. Generally,
their chemical composition strongly depends on the concentration of hydrogen ion,
so, it is a function of pH [15].
The laboratory studies of red–ox interaction of hydroxysulfate Green Rust
suspense with the solution of aurichlorohydric acid showed the formation of free
aurum clusters (2.9–7.7 nm) that form more complicate structures up to tens and
hundreds of nanometers [12]. The results of other investigation confirmed [16,
17] that introduction of AuCl n (OH) 4−n solution into GR(SO 4
2− ) dispersion under
nitrogen atmosphere leads to the formation of mixed Green Rust–aurum associates
and their following destruction and appearance of the individual gold and magnetite
15–30 nm particles.
While the contact of the hydroxysulfate and hydroxycarbonate Fe(II)–Fe(III)
LDHs with water AuCl 4
– complexes can carry out via solid-state Green Rust oxidation accompanied with reductive sedimentation of gold nanoparticles on their surface.
For example, the size of gold particles equaled 10–60 nm when the phase GR(CO 3
2− )
was applied as a nanoreactor, but it increased up to 20–120 nm when the phase
GR(SO 4
2− ) was used for the performing out the synthesis procedure [18]. Hence,
analysis of the referred data shows that interaction of aurum-containing species with
iron (oxy)hydroxide particles, (such as Fe(II)–Fe(III) layered double hydroxides
(LDHs), can be carried out via varies chemical mechanisms that caused by the physical–chemical conditions of the phase formation processes and the genesis of the
ferrous-bearing phases as well.
Generally, the process of the development of ferric–ferrous LDHs on the iron
and steel surface was taken as a basis of the formation nanosized ferrimagnetic iron
oxide particles under the process called rotation–corrosion dispergation (RCD). The
process of phase formation in our system is based on simple red–ox reactions (such
O. Lavrynenko et al.
impurities free magnetite and, simultaneously, such nanoparticles showed semiconducting behavior [9]. Moreover, the combination of plasmonic properties alongside
magnetic was notified for magnetite particles preliminarily doped by silver [10].
The interaction of aurum (III) aquaforms with iron oxyhydroxides in natural
systems may occur via adsorption mechanisms [11] and accompanied by donating
electron that supplied reduction of dissolved aurum complexes to the metallic state
during the steps of oxidation of the sulfide or oxide minerals [12]. Ferrous cations
of magnetite or Green Rust structures can reduce aurum concentration and precipitate gold on the oxidized mineral surface. By the second way the interaction of
ferrous cations, as a product of the dissolution of corresponding minerals with aurumcontaining complexes takes place in the subsurface waters and water solutions. Such
kind of reactions leads to the simultaneous precipitation of gold particles and disperse
iron oxides. Hence, the ferrous-containing minerals and mineraloids (colloid particles) play a big role in supergene systems for the secondary silver and gold deposits
formation [13] and take place in biogeochemical cycles of iron, aurum, and argentum,
as well [14]. As a rule, gold species adsorption on the surface of iron oxyhydroxides
accompanied by the formation of varies inner-sphere surface complexes. Generally,
their chemical composition strongly depends on the concentration of hydrogen ion,
so, it is a function of pH [15].
The laboratory studies of red–ox interaction of hydroxysulfate Green Rust
suspense with the solution of aurichlorohydric acid showed the formation of free
aurum clusters (2.9–7.7 nm) that form more complicate structures up to tens and
hundreds of nanometers [12]. The results of other investigation confirmed [16,
17] that introduction of AuCl n (OH) 4−n solution into GR(SO 4
2− ) dispersion under
nitrogen atmosphere leads to the formation of mixed Green Rust–aurum associates
and their following destruction and appearance of the individual gold and magnetite
15–30 nm particles.
While the contact of the hydroxysulfate and hydroxycarbonate Fe(II)–Fe(III)
LDHs with water AuCl 4
– complexes can carry out via solid-state Green Rust oxidation accompanied with reductive sedimentation of gold nanoparticles on their surface.
For example, the size of gold particles equaled 10–60 nm when the phase GR(CO 3
2− )
was applied as a nanoreactor, but it increased up to 20–120 nm when the phase
GR(SO 4
2− ) was used for the performing out the synthesis procedure [18]. Hence,
analysis of the referred data shows that interaction of aurum-containing species with
iron (oxy)hydroxide particles, (such as Fe(II)–Fe(III) layered double hydroxides
(LDHs), can be carried out via varies chemical mechanisms that caused by the physical–chemical conditions of the phase formation processes and the genesis of the
ferrous-bearing phases as well.
Generally, the process of the development of ferric–ferrous LDHs on the iron
and steel surface was taken as a basis of the formation nanosized ferrimagnetic iron
oxide particles under the process called rotation–corrosion dispergation (RCD). The
process of phase formation in our system is based on simple red–ox reactions (such