HYDROTALCITE

CAS NUMBER: 11097-59-9

EC NUMBER: 234-319-3

MOLECULAR FORMULA: Mg6Al2(CO3)(OH)16•4H2O

MOLECULAR WEIGHT: 603.98

Hydrotalcite is a layered double hydroxide (LDH) of general formula whose name is derived from its resemblance with talc and its high water content. 
Multiple structures containing loosely bound carbonate ions exist. 
The easily exchanged carbonates allow for applications of the mineral in wastewater treatment and nuclear fuel reprocessing.
Hydrotalcite, a magnesium–aluminum hydroxycarbonate, is a naturally occurring mineral of chemical composition Mg6Al2(OH)16CO3 4H2O exhibiting a layered crystal structure, which is comprised of positively charged hydroxide layers and interlayers composed of carbonate anions and water molecules. 

The most common method applied to preparation of hydrotalcite-like compounds is coprecipitation, which is based on the reaction of a solution containing both metal cations in adequate proportions with an alkaline solution. 
The products obtained by coprecipitation at low supersaturation are usually more crystalline in comparison with those prepared at high supersaturation conditions.
However, the product crystallinity may be affected by various experimental parameters such as reaction pH and temperature, concentration of used solutions, flow rate during addition of reactants, hydrodynamic conditions in the reactor and/or postsynthesis operations
Hydrotalcite is a Layered Double Hydroxide whose name is derived from its resemblance with talc and its high water content. 
Layered double hydroxides (LDH) comprise an unusual class of layered materials with positively charged hydroxide layers and charge balancing, mobile anions located in the interlayer region. 

This structure gives these material anion-exchange properties. 
The natural form of hydrotalcite is mined in small quantities in the Snarum area of Norway and the Ural area of Russia. 
Carl Christian Hochstetter (1842) was the first to report about hydrotalcite, which was attached firmly to a schist. 
He described a white material with a pearl like luster, with the formula Mg6Al2(OH)16CO3 . 4H2O.
Kyowa Chemical Industry of Japan (Kyowa) noticed the unique structure of hydrotalcite and became the first in the world to succeed in the industrial synthesis of the material in 1966. 

Shortly after that, Kyowa's synthetic hydrotalcite found its way to the pharmaceutical industry, where it was applied as an antacid agent. 
Today, the material is sold by globally known pharmaceutical firms and continues to be widely supplied to various nations all over the world.
Following the successful introduction of hydrotalcite in the pharmaceutical industry, Kyowa and its subsidiaries succeeded in developing new applications for its synthetic hydrotalcites. 
One of the most noteable results is the largescale usage of hydrotalcite by the global plastic production and processing industry. 
Traditionally, plastic compounds used to contain heavy metal stabilizers. However adverse effects on the human body, environmental destruction, etc. of such heavy metals had lead to critisicm which opened the way to more environmentally friendly stabilizer systems in which our synthetic hydrotalcites play a pivotal role.

An enormous amount of research is dedicated to study synthetic hydrotalcite and its suitability for applications including, but certainly not limited to, anti-corrosion, catalysis, encapsulation, controlled release and water technology. 
Kisuma Chemicals and Kyowa Chemical Industry are at the forefront of this development, offering support to innovation where possible. 
We are technically and commercially interested in all developments concerning these environmentally friendly materials.
Hydrotalcite-like anionic clays (HTs; or layered double hydroxides, LDHs) can be used as precursors to mixed oxides, but their catalytic potential reaches much further. 
This review demonstrates that HTs can be successfully applied in a broad spectrum of organic reactions, with advantages such as improved activity, selectivity, metal dispersion, less waste production, and an improved recuperation of immobilized catalysts. 
Hydrotalcites can be used in the as-synthesized form or after different pretreatments. 
The Hydrotalcite as such is a solid base or, depending on the elemental composition of its octahedral layers, may have redox properties. 

Specific metals can be incorporated either as a cation in the octahedral layer or as an anion via exchange. 
The anion-exchange strategy is especially successful in the context of heterogenizing homogeneous catalysts. 
A particular advantage for base catalysis is that the number and strength of the basic sites can be tuned precisely to a specific reaction. 
HTs are excellent materials to design bifunctional redox-base catalysts or to control the acid–base properties around a heterogenized metal complex. 
Potential applications of HTs range from the production of large-scale basic chemicals to the synthesis of small-scale specialty chemicals.
Hydrotalcite is a layered double hydroxide (LDH) of general formula Mg₆Al₂CO₃(OH)₁₆·4H₂O, whose name is derived from its resemblance with talc and its high water content. 

Multiple structures containing loosely bound carbonate ions exist. 
The easily exchanged carbonates allow for applications of the mineral in wastewater treatment and nuclear fuel reprocessing.
Hydrotalcite-like compounds (HT), layered double hydroxides with a few kinds of interlayer anions (X=CO32−, Cl−, and NO3−) were allowed to react with acrylate anions in order to prepare a novel inorganic–organic interstratified layered material by anion exchange. 
When HT–CO3 was used the anion exchange reaction did not occur. 
When HT–NO3 was employed the reaction proceeded to form a HT–acrylate intercalation compound. 
The formation of the intercalation compound from HT–Cl was observed only under a reaction condition using a concentrated acrylate solution. 

When the intercalation compound was heated at 80 °C with the addition of an initiator, the interlayer acrylate anions were polymerized to form a HT–polyacrylate intercalation compound.
Hydrotalcite is used in the treatment of stomach disorders (heartburn, heartburn, bloating, indigestion), dyspepsia, gastritis, gastric and duodenal ulcers, reflux esophagitis and reflux symptoms in hiatus hernia, which are manifested by hyperacidity.
Hydrotalcite is also used in the treatment of pregnancy and nervous indigestion and hyperacidity symptoms caused by overeating, coffee, alcohol, nicotine and some drugs.

Hydrotalcite and famotidine have been compared in an open, randomized, parallel-group study in 53 patients with endoscopically proven gastro-esophageal reflux disease, of whom 26 received a single dose of hydrotalcite 1 g and 27 a single dose of famotidine 10 mg for episodes of symptomatic reflux (1c). 
Hydrotalcite was significantly superior to famotidine in increasing the proportion of responders within the first 45 minutes, starting 10 minutes after drug administration. 
At 60–120 minutes, both compounds were equally efficacious. 
There were no adverse events in either group.
Hydrotalcite-like compounds (HTLcs) has been proposed as potential carbonization mitigation in cementitious composites due to their ability to absorb carbon dioxide. 

However, the adsorption capacity of normal HTLcs is limited due to their low specific surface area. 
In this paper, the high specific surface area HTLcs with added sodium dodecyl sulfate (SDS) via the co-precipitation process was fabricated and the cementitious composites with HTLcs was prepared. The phase composition and microstructure of HTLcs were characterized via x-ray diffraction (XRD), BET specific surface area and scanning electron microscope (SEM). 
The results show that specific surface area of HTLcs increases with an increase of SDS concentration, and the HTLcs have lower crystallinity when the concentration of SDS above 0.004 mol l−1. 

Mechanical property of cementitious composites increase as HTLcs content varying from 0% to 1% and then decrease as HTLcs content rise from 1% to 2%. 
Meanwhile, the carbonation depth of cementitious composites with HTLcs descends significantly with the increase of HTLcs content due to the high specific surface area, which shows a good carbonization resistance.

USES:

Hydrotalcites are used in technology as catalysts and anion exchangers and are important sinks for environmental contaminants. 
Their compositional variability makes it important, but difficult, to estimate their aqueous solubility. 
We report calorimetric measurements of the heats of formation of cobalt-aluminum hydrotalcite phases. 
The heat and free energy of formation from the elements are equal to those of mechanical mixtures of binary compounds, namely hydroxides and carbonates. 
The interlayer anion is much more important than the cation in determining the solubility of the hydrotalcite phase and its ability to contain or release heavy metals to the environment. 
Because hydrotalcites do not have an unreactive polymer as a structural core, their aqueous stability will change dramatically with composition, particularly with anion content. 
This simple mechanical mixture model allows prediction of aqueous solubilities and trace metal retention in a variety of geochemical settings.

APPLICATION:

Hydrotalcite has been studied as potential getter for iodide in order to scavenge the long-lived 129I (T1/2 = 15.7 million years) and also other fission products such as 79Se (T1/2 = 327,000 years) and 99Tc, (T1/2 = 211,000 years) present in spent nuclear fuel to be disposed under oxidising conditions in volcanic tuff at the Yucca Mountain nuclear waste repository. 
However, carbonate anions easily replace iodide anions in its interlayer and therefore the selectivity coefficient for the anion exchange is not favorable. 
Another difficulty arising in the quest of an iodide getter for radioactive waste is the long-term stability of the sequestrant that must survive over geological time scales.

Treating mining and other wastewater by creating hydrotalcites often produces substantially less sludge than lime. 
In one test, final sludge reductions reached up to 90 percent. 
This alters the concentration of magnesium and aluminum and raises the pH of water. 
As the crystals form, they trap other waste substances including radium, rare earths, anions and transition metals. 
The resulting mixture can be removed via settling, centrifuge, or other mechanical means.

STRUCTURE:

Hydrotalcite was first described in 1842 for an occurrence in a serpentine magnesite deposit in Snarum, Modum, Buskerud, Norway.
Hydrotalcite occurs as an alteration mineral in serpentinite in association with serpentine, dolomite and hematite.
The layers of the structure stack in multiple ways, to produce a 3-layer rhombohedral structure (3R Polytype), or a 2-layer hexagonal structure (2H polytype) formerly known as manasseite. 
The two polytypes are often intergrown.

PRECAUTION:

Before using this medicine, tell your doctor about your current medications, over-the-counter medications (for example, vitamins, herbal supplements, etc.), allergies, past illnesses, and current health conditions (for example, pregnancy, upcoming surgery, etc.). please inform. 
Some health conditions may make you more susceptible to the side effects of the drug. 
Take the steps as directed by your doctor or take into account what is written on the product. 
The dosage depends on your situation. If your condition persists or worsens, notify your doctor. 
Important topics to consult are listed below.

-Tell your doctor if you are allergic to hydrotalcite.
-Ask your doctor if you are pregnant or breastfeeding.

If you use other drugs or over the counter products at the same time, the effects of Hydrotalcite / Hydrotalcite may change. 
This may increase the risk of side effects or cause the medicine to not work properly. 
Tell your doctor about all medications, vitamins, and herbal supplements you use so your doctor can prevent drug interactions. 
Hydrotalcite / Hydrotalcite may interact with the following drugs or products:
Hypersensitivity to Hydrotalcite / Hydrotalcite is a contraindication. 
In addition, do not use Hydrotalcite / Hydrotalcite if you have:

-allergic reactions
-hypersensitivity

INTERACTIONS:

Talcid; Since it may affect the absorption of drugs such as tetracycline, iron preparations, digoxin, cimetidine, chenodesoxycholic acid and coumarin derivatives, they should not be taken with these drugs. 
Other drugs should be taken 1-2 hours before or after Talcid. 
Hydrotalcite has no adverse effects on laboratory tests.

WARNINGS:

In individuals with renal insufficiency (creatinine clearance < 30 ml/min), serum magnesium and aluminum levels should be checked at regular intervals and prolonged administration with high dosages should be avoided. When used for a long time, serum aluminum level should be checked and care should be taken not to exceed 40 µg/ml.
Hydrotalcite is generally recommended not to take any other medication within 1-2 hours of taking an antacid.
No harmful effects have been reported with Talcid Chewable Tablets during pregnancy and breastfeeding.

SYNONYM:

Ultacit
Talcid
Hidrotalcita
Hydrotalcitum
Altacet
Altacide
Altacite
Kyoward 600
Hydrotalcitum [INN-Latin]
Hidrotalcita [INN-Spanish]
DHT 4
Hydrotalcite [INN:BAN:JAN]
BAY4516H
BAY 4516H