7440-66-6 Usage
Uses
Used in Alloys:
Zinc is a constituent of many common alloys, including brass, bronze, Babbit metal, and German Silver. It is used to make household utensils, castings, printing plates, building materials, electrical apparatus, dry-cell batteries, and many zinc salts.
Used in Galvanization:
Zinc is used to galvanize sheet iron, providing a protective coating against corrosion. Such galvanized steel is used in buildings, cars, and appliances.
Used in Chemical Additives:
Zinc is used as a chemical additive in rubber and paints, contributing to their properties and performance.
Used in Die Castings:
High-purity zinc is alloyed with aluminum at varying compositions, along with small amounts of copper and magnesium, to produce die castings. Such die castings are used extensively in automotive, hardware, and electrical industries.
Used in Laboratory:
Zinc is used in the laboratory for preparing hydrogen gas and as a reducing agent in a number of chemical reactions.
Used in Nutrition:
Zinc is an essential nutrient element required for growth of animals and functions as a nutrient and dietary supplement. It is believed to be necessary for nucleic acid metabolism, protein synthesis, and cell growth.
Used in Agriculture:
Zinc is used in agriculture for galvanizing, which protects structures from corrosion and extends their lifespan.
Used in Health and Skincare:
Zinc is considered an anti-oxidant, offering protection against UV radiation, and is believed to accelerate wound healing. It is also used in acne treatments because it lowers sebaceous secretion and is used in the treatment of psoriasis. Zinc is a component of more than 70 metal enzymes and promotes collagen synthesis in the dermis and keratinization of the corneum layer.
Isotopes
There are 38 isotopes of zinc, ranging in atomic weights from Zn-54 to Zn-83.Just four of these are stable, and those four, plus one naturally radioactive isotope (Zn-70) that has a very long half-life (5×10+14 years), make up the element’s existence onEarth. Their proportional contributions to the natural existence of zinc on Earth are assuch: Zn-64 = 48.63%, Zn-66 = 27.90%, Zn-67 = 4.10%, Zn- 68 = 18.75%, and Zn-70 = 0.62%. All the other isotopes are radioactive and artificially produced.
Origin of Name
Although ancients used zinc compounds, the name “zinc” is assumed
to be derived from the German word zinn, which was related to tin.
Characteristics
Zinc is malleable and can be machined, rolled, die-cast, molded into various forms similarto plastic molding, and formed into rods, tubing, wires, and sheets. It is not magnetic, butit does resist corrosion by forming a hard oxide coating that prevents it from reacting anyfurther with air. When used to coat iron, it protects iron by a process called “galvanic protection,” also known as “sacrificial protection.” This protective characteristic occurs because theair will react with the zinc metal coating, which is a more electropositive (reactive) metal thanis the coated iron or steel, which is less electropositive than zinc. In other words, the zinc isoxidized instead of the underlying metal. (See the section under “Common Uses of Zinc” formore on galvanization.
History
Centuries before zinc was recognized as a distinct element,
zinc ores were used for making brass. Tubal-Cain, seven generations
from Adam, is mentioned as being an “instructor in
every artificer in brass and iron.” An alloy containing 87%
zinc has been found in prehistoric ruins in Transylvania.
Metallic zinc was produced in the 13th century A.D. in India
by reducing calamine with organic substances such as wool.
The metal was rediscovered in Europe by Marggraf in 1746,
who showed that it could be obtained by reducing calamine
with charcoal. The principal ores of zinc are sphalerite or
blende (sulfide), smithsonite (carbonate), calamine (silicate),
and franklinite (zinc, manganese, iron oxide). Canada, Japan,
Belgium, Germany, and the Netherlands are suppliers of zinc
ores. Zinc is also mined in Alaska, Tennessee, Missouri, and
elsewhere in the U.S. Zinc can be obtained by roasting its
ores to form the oxide and by reduction of the oxide with coal
or carbon, with subsequent distillation of the metal. Other
methods of extraction are possible. Naturally occurring zinc
contains five stable isotopes. Twenty-five other unstable
isotopes and isomers are recognized. Zinc is a bluish-white,
lustrous metal. It is brittle at ordinary temperatures but malleable
at 100 to 150°C. It is a fair conductor of electricity, and
burns in air at high red heat with evolution of white clouds
of the oxide. The metal is employed to form numerous alloys
with other metals. Brass, nickel silver, typewriter metal,
commercial bronze, spring brass, German silver, soft solder,
and aluminum solder are some of the more important alloys.
Large quantities of zinc are used to produce die castings,
used extensively by the automotive, electrical, and hardware
industries. An alloy called Prestal?, consisting of 78% zinc
and 22% aluminum, is reported to be almost as strong as
steel but as easy to mold as plastic. It is said to be so plastic
that it can be molded into form by relatively inexpensive die
casts made of ceramics and cement. It exhibits superplasticity.
Zinc is also extensively used to galvanize other metals
such as iron to prevent corrosion. Neither zinc nor zirconium
is ferromagnetic; but ZrZn2 exhibits ferromagnetism
at temperatures below 35 K. Zinc oxide is a unique and very
useful material to modern civilization. It is widely used in the
manufacture of paints, rubber products, cosmetics, pharmaceuticals,
floor coverings, plastics, printing inks, soap,
storage batteries, textiles, electrical equipment, and other
products. It has unusual electrical, thermal, optical, and solid-
state properties that have not yet been fully investigated.
Lithopone, a mixture of zinc sulfide and barium sulfate, is
an important pigment. Zinc sulfide is used in making luminous
dials, X-ray and TV screens, and fluorescent lights. The
chloride and chromate are also important compounds. Zinc
is an essential element in the growth of human beings and
animals. Tests show that zinc-deficient animals require 50%
more food to gain the same weight as an animal supplied
with sufficient zinc. Zinc is not considered to be toxic, but
when freshly formed ZnO is inhaled a disorder known as the
oxide shakes or zinc chills sometimes occurs. It is recommended
that where zinc oxide is encountered good ventilation
be provided. The commercial price of zinc in January
2002 was roughly 40￠/lb ($90 kg). Zinc metal with a purity of
99.9999% is priced at about $5/g.
Production Methods
Zinc is widely distributed in nature, constituting 20–200 ppm
of the Earth’s crust.The principal zinc ore is in the form of sulfides, such as
sphalerite and wurtzite (cubic and hexagonal ZnS) and
willemite (Zn2SiO4). To obtain metallic zinc, the zinc ores
that are relatively low in zinc content are concentrated. Zinc
smelting is gradually being replaced by the electrolytic
processes. During smelting there are often large emissions
of zinc, and other heavy metals contained in the zinc ore such
as lead and cadmium, into the air.
Reactions
Zinc exhibits a valence of +2 in all its compounds. It also is a highly electropositive metal. It replaces less electropositive metals from their aqueous salt solutions or melts. For example, a zinc metal bar put into Cu2+ solution acquires a brown-black crust of copper metal deposited on it. At the same time the blue color of the solution fades. Zinc reduces Cu2+ ions to copper metal. The overall reaction is:
Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s)
This spontaneous reaction was used first in 1830 to make a voltaic cell. The metal is attacked by mineral acids. Reactions with sulfuric and hydrochloric acids produce hydrogen. With nitric acid, no hydrogen is evolved but the pentavalent nitrogen is reduced to nitrogen at lower valence states. Zinc is attacked by moist air at room temperature. Dry air has no action at ambient temperatures but the metal combines with dry oxygen rapidly above 225°C. Zinc reacts with carbon dioxide in the presence of moisture at ordinary temperatures forming a hydrated basic carbonate. The metal, on heating with dry halogen gases, yields zinc halides. However, in the presence of moisture the reaction occurs rapidly at ambient temperatures. The metal dissolves in hot solutions of caustic alkalis to form zincates and evolves hydrogen:
Zn + 2NaOH → Na2ZnO2 + H2
Air & Water Reactions
Can evolve gaseous hydrogen in contact with water or damp air. The heat of the reaction may be sufficient to ignite the hydrogen produced [Haz. Chem. Data 1966. p. 171]. Flammable. May form an explosive mixture with air [Hawley].
Reactivity Profile
ZINC METAL is a reducing agent. Reacts violently with oxidants causing fire and explosion hazards [Handling Chemicals Safely 1980. p. 966]. In the presence of carbon, the combination of chlorine trifluoride with zinc results in a violent reaction [Mellor 2, Supp. 1: 1956]. Sodium peroxide oxidizes zinc with incandescence [Mellor 2:490-93 1946-47]. Zinc powder or dust in contact with acids forms hydrogen. The heat generated by the reaction is sufficient to ignite the hydrogen evolved [Lab. Govt. Chemist 1965]. A mixture of powdered zinc and an oxidizing agent such as potassium chlorate or powdered sulfur can be exploded by percussion. Zinc burns in moist chlorine. A mixture of zinc and carbon disulfide reacts with incandescence. Zinc powder reacts explosively when heated with manganese chloride. The reaction between zinc and selenium or tellurium is accompanied by incandescence [Mellor 4:476-480 1946-47]. When zinc and ammonium nitrate are mixed and wetted with a minimum of water, a violent reaction occurs with evolution of steam and zinc oxide. When hydrazine mononitrate is heated in contact with zinc a flaming decomposition occurs at temperatures a little above its melting point. Hydroxylamine is reduced when heated with ZINC, unpredictably ZINC may either ignite and burn or explode [Mellor 8 1946-47].
Hazard
As mentioned, zinc dust and powder are very explosive. When zinc shavings are placedin acid or strong alkaline solutions, hydrogen gas is produced, which may explode. Many ofzinc’s compounds are toxic if inhaled or ingested. A deficiency of zinc in humans will retard growth, both physically and mentally, andcontribute to anemia. It is present in many foods, particularly proteins (meat). A balanceddiet provides an adequate amount of zinc. Not more than 50 milligrams per day of dietaryzinc supplement should be taken, given that high levels of zinc in the body are toxic. Humanbodies contain about two grams of zinc. A deficiency of zinc can cause a lack of taste and candelay growth as well as cause retardation in children.Zinc intoxication can occur both from inhaling zinc fumes and particles, mainly in industrialprocesses, and from orally ingesting an excess of zinc in dietary supplements. Zinc intoxicationcan cause stomach pains, vomiting, and bleeding. Excess zinc also can cause prematurebirth in pregnant women.
Health Hazard
Zinc and its compounds are relatively non-toxic, but very large doses can produce an acute gastroenteritis characterized by nausea, vomiting, and diarrhea. The recommended dietary allowance (RDA) for zinc is 15 mg/day for men, 12 mg/day for women, 10 mg/day for children, and 5 mg/day for infants. Insuffi cient zinc in the diet can result in a loss of appetite, a decreased sense of taste and smell, slow wound healing and skin sores, or a damaged immune system. Pregnant women with low zinc intake have babies with growth retardation. Exposure to zinc in excess, however, can also be damaging to health. Harmful health effects generally begin at levels from 10–15 times the RDA (in the 100–250 mg/day range). Eating large amounts of zinc, even for a short time, can cause stomach cramps, nausea, and vomiting. Chronic exposures to zinc chloride fumes cause irritation, pulmonary edema, bronchopneumonia, pulmonary fi brosis, and cyanosis. It also causes anemia, pancreas damage, and lower levels of high-density lipoprotein cholesterol. Breathing large amounts of zinc (as dust or fumes) can cause a specifi c short-term disease, called metal fume fever, including disturbances in the adrenal secretion. Information on the possible toxicological effects following prolonged period of exposures to high concentrations of zinc is not known.
Fire Hazard
Produce flammable gases on contact with water. May ignite on contact with water or moist air. Some react vigorously or explosively on contact with water. May be ignited by heat, sparks or flames. May re-ignite after fire is extinguished. Some are transported in highly flammable liquids. Runoff may create fire or explosion hazard.
Flammability and Explosibility
Notclassified
Pharmaceutical Applications
The average human body contains around 2 g of Zn2+. Therefore, zinc (after iron) is the second most abundant
d-block metal in the human body. Zinc occurs in the human body as Zn2+ (closed d10 shell configuration),
which forms diamagnetic and mainly colourless complexes. In biological systems, zinc ions are often
found as the active centre of enzymes, which can catalyse metabolism or degradation processes, and are
known to be essential for stabilising certain protein structures that are important for a variety of biological
processes.
Already from ancient times, Zn2+ was known to have important biological properties. Zinc-based
ointments were traditionally used for wound healing. Low Zn2+ concentrations can lead to a variety of
health-related problems especially in connection with biological systems of high Zn2+ demand such as the
reproductive system. The daily requirement for Zn2+ is between 3 and 25 mg, depending on the age and
circumstances.
The enzymatic function of Zn2+ is based on its Lewis acid activity, which are electron-deficient species. In the following chapters, examples will be shown to further explain this. Carboanhydrase (CA),carboxypeptidase and superoxide dismutase are some examples for well-studied zinc-containing enzymes.
The so-called zinc fingers have been discovered because of the crucial role of Zn2+ in the growth of organisms.
Within the zinc finger, Zn2+ stabilises the protein structure and therefore enables its biological function.
Safety Profile
Human systemic effects
by ingestion: cough, dyspnea, and sweating.
A human skin irritant. Pure zinc powder,
dust, and fume are relatively nontoxic to
humans by inhalation. The dfficulty arises
from oxidation of zinc fumes immedately
prior to inhalation or presence of impurities
such as Cd, Sb, As, Pb. Inhalation may cause
sweet taste, throat dryness, cough, weakness,
generalized aches, chills, fever, nausea,
vomiting.
Flammable in the form of dust when
exposed to heat or flame. May i p t e
spontaneously in air when dry. Explosive in
the form of dust when reacted with acids.
Incompatible with NH4NO3, BaO2,
Ba(NO3)2, Cd, CS2, chlorates, Cl2, ClF3,
CrO3, (ethyl acetoacetate + tribromoneo-
pentyl alcohol), F2, hydrazine mononitrate,
hydroxylamine, Pb(N3)2, (Mg + Ba(NO3)2 +
BaO2), MnCl2, HNO3, performic acid,
KCLO3, KNO3, K2O2, Se, NaClO3, Na2O2,
S, Te, H2O2 (NH4)2S, As2O3, CS2, CaCl2,
NaOH, chlorinated rubber, catalytic metals,
halocarbons, o-nitroanisole, nitrobenzene,
nonmetals, oxidants, paint primer base,
pentacarbonyliron, transition metal halides,
seleninyl bromide. To fight fire, use special
mixtures of dry chemical. When heated to
decomposition it emits toxic fumes of ZnO.
See also ZINC COMPOUNDS.
Potential Exposure
Zinc is used most commonly as a
protective coating of other metals. In addition, it is
used in alloys, such as bronze and brass, for electrical
apparatus in many common goods; and in organic
chemical extractions and reductions. Zinc chloride is a
primary ingredient in smoke bombs used by military
for screening purposes, crowd dispersal and occasionally
in firefighting exercises by both military and civilian
communities. In pharmaceuticals, salts of zinc are
used as solubilizing agents in many drugs, including
insulin.
Carcinogenicity
Repeated intratesticular injections
of zinc chloride to chickens and rats have been reported
to produce testicular sarcomas. There is no evidence that zinc
compounds are carcinogenic after administration by any
other route. Zinc oxide, zinc chloride, and zinc stearate
have been classified by the U.S. EPAas belonging to group D.
Environmental Fate
Zinc enters the air, water, and soil as a result of both natural
processes and human activities. Most zinc enters the environment
as the result of human activities, such as mining, purifying
of zinc, lead, and cadmium ores, steel production, coal
burning, and burning of wastes. These releases can increase zinc
levels in the atmosphere. Waste streams from zinc and other
metal manufacturing and zinc chemical industries, domestic
wastewater, and runoff from soil containing zinc can discharge
zinc into waterways. The level of zinc in soil increases mainly
from disposal of zinc wastes from metal manufacturing
industries and coal ash from electric utilities. In air, zinc is
present mostly as fine dust particles. This dust eventually settles
over land and water. Rain and snow aid in removing zinc from
air. Most of the zinc in bodies of water, such as lakes or rivers,
settles on the bottom. However, a small amount may remain
either dissolved in water or as fine suspended particles. The
level of dissolved zinc in water may increase as the acidity of
water increases. Some fish can collect zinc in their bodies if they
live in water containing zinc. Most of the zinc in soil is bound
to the soil and does not dissolve in water. However, depending
on the characteristics of the soil, some zinc may reach
groundwater. Contamination of groundwater from hazardous
waste sites has been noticed. Zinc may be taken up by animals
eating soil or drinking water containing zinc. If other animals
eat these animals, they will also have increased amounts of zinc
in their bodies.
Shipping
UN1436 Zinc powder or zinc dust, Hazard
Class: 4.3; Labels: 4.3-Dangerous when wet material,
4.2-Spontaneously combustible material.
Purification Methods
Commercial zinc dust (1.2kg) is stirred with 2% HCl (3L) for 1minute, then the acid is removed by filtration, and washed in a 4L beaker with a 3L portion of 2% HCl, three 1L portions of distilled water, two 2L portions of 95% EtOH, and finally with 2L of absolute Et2O. (The wash solutions were removed each time by filtration.) The material is then dried thoroughly, and if necessary, any lumps are broken up in a mortar. [Wagenknecht & Juza Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol II p 1067 1965.]
Toxicity evaluation
Zinc is essential for humans and animals. It is necessary for
the function of numerous enzymes include alcohol dehydrogenase,
alkaline phosphatase, carbonic anhydrase, and
superoxide dismutase. However, excessive zinc interferes with
iron and copper metabolism; the latter leads to copper-deficiency
anemia. Salts of strong mineral acids are corrosive to
skin and intestine. Zinc also plays an essential role in the
maintenance of the nucleic acid structure of genes and an
integral component of DNA polymerase and RNA polymerase.
Yet, a limited amount of zinc consumed leads to zinc
deficiency. Zinc deficiency decreases the production of DNA
and RNA, which results in the reduction of protein synthesis.
Incompatibilities
Dust is pyrophoric and may self-ignite in
air. A strong reducing agent. Violent reaction with oxidizers,
chromic anhydride; manganese chloride; chlorates,
chlorine and magnesium. Reacts with water and reacts violently
with acids, alkali hydroxides; and bases forming
highly flammable hydrogen gas. Reacts violently with sulfur,
halogenated hydrocarbons and many other substances,
causing fire and explosion hazard.
Waste Disposal
Zinc powder should be
reclaimed. Unsalvageable waste may be buried in an
approved landfill. Leachate should be monitored for zinc
content.
Check Digit Verification of cas no
The CAS Registry Mumber 7440-66-6 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 7,4,4 and 0 respectively; the second part has 2 digits, 6 and 6 respectively.
Calculate Digit Verification of CAS Registry Number 7440-66:
(6*7)+(5*4)+(4*4)+(3*0)+(2*6)+(1*6)=96
96 % 10 = 6
So 7440-66-6 is a valid CAS Registry Number.
InChI:InChI=1/Zn
7440-66-6Relevant articles and documents
Excitons and excitonic molecules in mixed Zn(P1-xAsx)2 crystals
Yeshchenko,Biliy,Yanchuk
, p. 231 - 238 (2001)
Low-temperature (1.8 K) excitonic absorption, reflection and photoluminescence spectra of mixed Zn(P1-xAsx)2 crystals have been studied at x = 0.01, 0.02, 0.03 and 0.05. Energy gap and rydbergs of excitonic B-, C- and A-series decrease monotonically with increasing of x. The spectral half-widths of the absorption n = 1 lines of the B- and A-series increase monotonically with increase in x due to fluctuations of crystal potential. Emission lines of excitonic molecules have been observed in photoluminescence spectra of Zn(P1-xAsx)2 crystals. The binding energy of the molecule increases with increase in x due to the decrease of the electron-hole mass ratio.
Zinc electrodeposition assisted by a pulsed YAG laser beam. Effects of hydrodynamic conditions
Zouari,Lapicque,Calvo,Cabrera
, p. 2163 - 2170 (1992)
The effect of a pulsed laser beam (YAG at 532 nm) on zinc deposition in a sulfate medium is studied. The deposition was carried out either in stagnant conditions or under forced laminar or turbulent convection of the electrolyte solution. The effect of pulse laser irradiation was investigated in terms of current density enhancement under controlled potential; it was also observed through the change in the deposit's morphology. The sharp temperature increase of the substrate surface, due to pulsed irradiation, results in higher current densities, a reduction in grain size, and coalescence phenomena corresponding to zinc diffusion into the zinc substrate. The influence of electrode potential, zinc sulfate concentration, and flow velocity is discussed: circulation of the solution is shown to hinder the laser effect due to the quenching of the zinc surface.
Investigation of Sn-Zn electrodeposition from acidic bath on EQCM
Arici, Mürsel,Nazir, Hasan,Aksu, M. Levent
, p. 1534 - 1537 (2011)
Tin-zinc (Sn-Zn) alloy with low tin content was deposited on gold electrode and steel substrate with use of chronoamperometric technique from an acidic bath. In order to evaluate coating efficiency of Sn-Zn alloy in 0.5 M NaCl solution, open circuit potential-time curve (EOCP-t), polarization curves, mass change of the electrode (Δm-t) using quartz crystal microbalance (QCM) were compared to those of pure Sn and Zn coatings. Anodic stripping measurements were carried out simultaneously with the mass loss of the deposit. Scanning electron microscopy (SEM) and energy dispersive X-ray spectra (EDS) analysis were performed to characterize the surface morphology. Anodic stripping experiment and EDS analysis indicated that Sn, Zn, and SnO2 formed on the electrode surface when Sn-Zn was coated from acidic bath. Furthermore, local mapping demonstrated homogeneous distribution of Sn and Zn atoms throughout the surface.
Electron-poor antimonides: Complex framework structures with narrow band gaps and low thermal conductivity
Haeussermann, Ulrich,Mikhaylushkin, Arkady S.
, p. 1036 - 1045 (2010)
Binary zinc and cadmium antimonides and their ternary relatives with indium display complex crystal structures, but reveal at the same time narrow band gaps in their electronic structure at or close to the Fermi level. It is argued that these systems represent electron-poor framework semiconductors (EPFS) with average valence electron concentrations between three and four. EPFS materials constituted of metal and semimetal atoms form a common, weakly polar framework containing multi-center bonded structural entities. The localized multi-center bonding feature is thought to be the key to structurally complex semiconductors. In this respect electron-poor antimonides become related to modifications of elemental boron. Electron-poor antimonides show promising thermoelectric properties, especially through a remarkably low thermal conductivity. At the same time the thermal stability of these compounds is rather limited because of temperature polymorphism and/or comparatively low melting or decomposition temperatures (usually below 600 K).
Influence of the alloying component on the protective ability of some zinc galvanic coatings
Boshkov,Petrov,Kovacheva,Vitkova,Nemska
, p. 77 - 84 (2005)
The composition of the corrosion products of pure Zn galvanic coatings as well as of some zinc alloys (Zn-Mn and Zn-Co) after treatment in selected free aerated model media (5% NaCl and 1N Na2SO4) is studied and discussed. X-ray diffraction and X-ray photoelectron spectroscopy investigations are used for this purpose. It is concluded that the corrosion products (zinc hydroxide chloride hydrate in 5% NaCl and zinc hydroxide sulfates hydrates in 1N Na2SO4) play a very important role for the improved protective ability of the zinc alloys toward the iron substrate, compared to the pure Zn coatings. Another result is that, for a given medium, the corrosion products are one and the same for both alloys independently of the fact that the alloying component is electrically more positive or negative than the zinc. Some suggestions about the models of the appearance of these products and their protective influence are also discussed.
Activation of Reduction Agents. Sodium Hydride Containing Complex Reducing Agents. 18. Study of the Nature of Complex Reducing Agents Prepared from Nickel and Zinc Salts
Brunet, Jean-Jacques,Besozzi, Denis,Courtois, Alain,Caubere, Paul
, p. 7130 - 7135 (1982)
Complex reducing agents NaH-RONa-MXn (referred to as MCRA) are new versatile reagents that have already found many applications in organic synthesis.In the present study, the composition and structure of NiCRA and ZnCRA (CRA prepared from a nickel salt and a zinc salt, respectively) have been investigated.It has been found that, in both reagents, the metal (Ni or Zn) is formallly in a zero-valent oxidation state.The active part of NiCRA is constituted of new species (formed from Ni0 (1 equiv), RONa (R = t-Bu) (2 equiv), NaH (2 equiv), and maybe some AcONa) in which each constituent has lost its own characteristics.A picture of the structure of these new species is proposed.The composition of the active part of ZnCRA is less clear.Indeed, associations between RONa (R = t-Am) and Zn0 have been evidenced, but these species do not exhibit the reducing properties of ZnCRA, e.g., toward carbonyl compounds.In fact, control experiments have shown that no ketone reduction occured in the absence of NaH.These observations led us to propose that the active part of ZnCRA should be constituted of associations of the type n, which may be formed, in low concentration, from NaH and the inactive species n.
Dynamic and controlled rate thermal analysis of hydrozincite and smithsonite
Vagvoelgyi, Veronika,Hales,Martens,Kristof,Horvath, Erzsebet,Frost
, p. 911 - 916 (2008)
The understanding of the thermal stability of zinc carbonates and the relative stability of hydrous carbonates including hydrozincite and hydromagnesite is extremely important to the sequestration process for the removal of atmospheric CO2. The hydration-carbonation or hydration-and-carbonation reaction path in the ZnO-CO2-H2O system at ambient temperature and atmospheric CO2 is of environmental significance from the standpoint of carbon balance and the removal of green house gases from the atmosphere. The dynamic thermal analysis of hydrozincite shows a 22.1% mass loss at 247°C. The controlled rate thermal analysis (CRTA) pattern of hydrozincite shows dehydration at 38°C, some dehydroxylation at 170°C and dehydroxylation and decarbonation in a long isothermal step at 190°C. The CRTA pattern of smithsonite shows a long isothermal decomposition with loss of CO2 at 226°C. CRTA technology offers better resolution and a more detailed interpretation of the decomposition processes of zinc carbonate minerals via approaching equilibrium conditions of decomposition through the elimination of the slow transfer of heat to the sample as a controlling parameter on the process of decomposition. The CRTA technology offers a mechanism for the study of the thermal decomposition and relative stability of minerals such as hydrozincite and smithsonite.
Unexpected visible light driven photocatalytic activity without cocatalysts and sacrificial reagents from a (GaN)1-: X(ZnO)x solid solution synthesized at high pressure over the entire composition range
Dharmagunawardhane, H. A. Naveen,James, Alwin,Wu, Qiyuan,Woerner, William R.,Palomino, Robert M.,Sinclair, Alexandra,Orlov, Alexander,Parise, John B.
, p. 8976 - 8982 (2018)
Optical and photocatalytic properties were determined for the solid solution series (GaN)1-x(ZnO)x synthesized at high pressure over the entire compositional range (x = 0.07 to 0.9). We report for the first time photocatalytic H2 evolution activity from water for (GaN)1-x(ZnO)x without cocatalysts, pH modifiers and sacrificial reagents. Syntheses were carried out by reacting GaN and ZnO in appropriate amounts at temperatures ranging from 1150 to 1200 °C, and at a pressure of 1 GPa. ZnGa2O4 was observed as a second phase, with the amount decreasing from 12.8 wt% at x = 0.07 to ～0.5 wt% at x = 0.9. The smallest band gap of 2.65 eV and the largest average photocatalytic H2 evolution rate of 2.31 μmol h-1 were observed at x = 0.51. Samples with x = 0.07, 0.24 and 0.76 have band gaps of 2.89 eV, 2.78 eV and 2.83 eV, and average hydrogen evolution rates of 1.8 μmol h-1, 0.55 μmol h-1 and 0.48 μmol h-1, respectively. The sample with x = 0.9 has a band gap of 2.82 eV, but did not evolve hydrogen. An extended photocatalytic test showed considerable reduction of activity over 20 hours.
Pattern formation of zinc nanoparticles in silica film by electrodeposition
Pal,Chakravorty
, p. 20917 - 20921 (2006)
Zinc nanoparticles were grown within gel-derived silica films by applying a direct current voltage. Pattern formation of metallic Zn was studied as a function of applied voltage and metal-silica ratio. Average particle size varied from 5.2 to 20.2 nm by changing the applied voltage and silica concentration. It was found that the transition from fractal to dendritic morphology was possible due to crystalline anisotropy. From high-resolution transmission electron microscopy images and X-ray diffraction pattern a possible model is proposed to explain this observation.
PHOTOCATALYSIS OF ZINC SULFIDE MICROCRYSTALS IN REDUCTIVE HYDROGEN EVOLUTION IN WATER/METHANOL SYSTEMS
Yanagida, Shozo,Kawakami, Hiroshi,Hashimoto, Kazuhito,Sakata, Tadayoshi,Pac, Chyongjin,Sakurai, Hiroshi
, p. 1449 - 1452 (1984)
In photocatalytic H2 evolution using an aq. methanol system, high quality microcrystalline (cubic) ZnS powders have been found to be active under an appropriate light intensity, which is comparable in activity with freshly prepared ZnS suspensions.Compari
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