Barium sulfate improves stiffness and also acoustic residential property while having fairly little effect on surface finish.

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From: Polypropylene, 1998

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Y. Nonomura, in cosmetics Science and Technology, 2017

14.2.1.1.5 Barium Sulfate

Barium sulfate, BaSO4, is do by reacting barium hydroxide and also other barium sources with sulfuric acid and also has a long history as a translucent white pigment. Barium sulfate have the right to be created in miscellaneous shapes such together planar, starred, or spherical structures relying on the formulation condition, particularly the supersaturation the its barium source, and the internal pore size additionally changes.18 Planar barium sulfate shows especially high lubricity, and when used to the skin it no only has actually a smooth feeling but additionally has a high light-scattering property, mirroring a soft-focus impact that makes little wrinkles and pores much less visible.19


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Group 16 (O, S, Se, Te) Alkaline earth Compounds


R.C. Ropp, in Encyclopedia of the Alkaline earth Compounds, 2013

Barium Sulfate


Barium sulfate has actually the molecule formula of BaSO4 and the molecular weight of 233.3896 g/mol. It have the right to be prepared by the reaction the barium carbonate and sulfuric acid:


BaCO3 + H2SO4 ⇒ BaSO4 + CO2 + H2O

Barium sulfate is a soft crystalline solid. It is a rhombic crystal. The pure salt is white yet the shade of the mineral “barite” have the right to vary in between red, yellow, gray or green, relying on impurities. Its thickness is 4.50 g/cm3 and its refractive index is 1.64. It melts roughly 1580 °C yet decomposes above 1600 °C. Its hardness is 4.3 come 4.6 Mohs. That is essentially insoluble in water (285 mg/l at 30 °C) and insoluble in alcohol. The Ksp is 1.1 × 10–10. It is soluble in focused sulfuric acid. The crystal framework of BaSO4 is known to be rhombic, with a an are group pnma. The lattice parameters are: a = 8.896 Å, b = 5.462°, c = 7.171 Å, V = 348.4 Å3. The three-dimensional structure is shown in Fig. 3.33.



FIGURE 3.33.


Strontium sulfate has actually an identical structure. Thernodynamic constants are offered by the adhering to table. This values are for 293 K (Table 3.14).


TABLE 3.14.


Thermochemical properties
Δ = –352.3 kcal/mol
ΔGf = –325.7 kcal/mol
S0 = 31.6 cal/degree mol
Cp = 24.3 cal/degree mol
ΔHfusion = 9.71 kcal/mol

Natural barium sulfate is widely dispersed in nature and also occurs as the mineral “barite” (also known as barytes or heavy spar). It often connected with other metallic ores, such as fluorspar. Barites containing over 94% BaSO4 deserve to be processed economically. It additionally contains silica, ferric oxide and also fluoride impurities. Silica is the element impurity that can be eliminated as salt fluorosilicate through treatment through hydrofluoric acid followed by caustic soda. Very pure barium sulfate may be acquired by dealing with an aqueous systems of a dissolve barium salt through sodium sulfate:


BaCl2 + Na2SO4 ⇒ BaSO4 + 2NaCl

Barium sulfate is just one of the many insoluble salt of the alkaline earths. It does no undergo dual decomposition reactions in aqueous phase choose its Mg homologue. It dissolves in focused H2SO4 to kind an mountain sulfate that breaks down to BaSO4 top top dilution. Reduction v coke under heating produces barium sulfide:


BaSO4 + 3C ⇒ BaS + 2CO + CO2

The accidental exploration of this conversion numerous centuries earlier led come the discovery of the an initial luminescent product in 1803. The sulfide, uneven the sulfate, is water soluble. Sometime prior to the loss of 1803, the Englishman man Dalton was able to explain the outcomes of several of his researches by assuming that issue is created of atoms and that every samples of any type of given compound consist of the same combination of these atoms. Dalton also detailed that in a collection of compounds favor barium sulfate, the ratios of the masses of the 2nd element that combine with a given weight of the very first element deserve to be diminished to tiny whole numbers (the law of multiple proportions). This to be further evidence for the existence of “atoms”.

BaSO4 reaction violently as soon as heated v aluminum or explosively when combined with potassium. Sulfamic acid, HSO3NH2 is a moderately strong acid. Water remedies are unstable and slowly hydrolyze come NH4HSO4. It has been used to create nanosized barium sulfate particles.

Barium sulfate has many commercial applications. It is supplied either as herbal barite, or precipitated BaSO4. The precipitated salt in mix with equimolar lot of co-precipitated zinc sulfide previously was offered as a white security coating pigment, well-known as “lithopone”. Similarly, in mix with salt sulfide, it is offered to create fine pigment particles of uniform size, known as “blanc fixe”. Natural barite, however, has better commercial application than the precipitation salt. The is offered as one additive in drilling mud in rudely oil, fine drilled come lubricate and also cool the drilling bit, and also to plaster the wall surfaces of the drill feet to avoid caving. That is provided as a filler in automotive paints, plastics and also rubber products. It likewise is offered as a filler in polyurethane foam floor mats, white sidewall rubber tires and also as a flux and also additive come glass to rise the refractive index.

Barium sulfate is commonly used clinically as a comparison agent because that X-ray imaging and other diagnostic procedures. That is most frequently used in imaging that the cradle tract. The is administered, orally or by enema, together a suspension the fine particles in one aqueous solution. Back barium, and also its water-soluble compounds are often highly toxic, the incredibly low solubility of barium sulfate protects the patient from absorbing harmful quantities of the metal. Barium sulfate is likewise readily eliminated from the body, unlike prior compounds, which it replaced. That is absorbance the X-rays is also higher.

Barium sulfate mixture are supplied as white pigment because that paints. In oil paint, barium sulfate is virtually transparent, and also is used as a filler or to change consistency. One major manufacturer the artists’ oil paint sells “permanent white” that contains a mixture the titanium white pigment and barium sulfate. Barium sulfate chin is called blanc fixe (French for “permanent white”).

A scientific-grade, barium sulfate-based paint is offered for sale that exhibits near-perfect diffuse reflectance in ~ levels approximately 98% in the UV-VIS-NIR wavelength range. The is used by spray painting to nearly any substrate (metals, plastics, glass) for use in completely spheres, laser cavities, lamp reflectors and display backlights. It is characterized by a near-perfect Lambertian (i.e. Diffuse) reflectance of up to 98% in the spectral range from 250 come 2500 nm.

Other chemistry applications the barium sulfate are provided as a pigment for photographic paper. It is also used to prepare numerous other barium salts. It is obtainable in plenty of forms commercially.



The effect on the level that X-ray absorb (as shown by increasing amounts of observable image contrast) of including greater quantities of barium sulfate come PEEK can be seen in a conventional configuration presented in Fig. 3.9. Here the emergence compounds comprise 4%, 6%, and also 20% by weight of barium sulfate powder have been molded right into rectangular pieces at different thicknesses ranging from 2 come 10 mm in 2 mm increments and assembled in the bespeak shown. Next to these is a machined aluminum “stepped wedge” that the very same dimensions by way of comparison. It deserve to be watched that the link containing 20% barium sulfate matches really closely the radiopacity the the steel at like-for-like thicknesses. By selecting compounds containing 4%, 6%, or 20% barium sulfate, the implant developer can, therefore, tailor the quantity of radiopacity of the machine to accomplish an optimized level the contrast. The radiographs presented in Fig. 3.10 highlight this because that PEEK-OPTIMA polymer spinal combination cages that have been made through no additive and also 6% and 20% image contrast additive, respectively, compared with a metallic cage.




Substantially, as a an effect of their shape, powders perform not improve the tensile toughness of polymer materials contrasted with fiber reinforcements, back there room physical changes to the base polymer that take place as a an outcome of your addition. Table 3.2 compares the mechanically properties that barium sulfate-filled PEEK v unfilled PEEK. It have the right to be watched that boosting the amount of filler actually reduces the tensile strength of the product from 100 with 95 MPa, come 90 MPa v the highest possible filler loading. This stamin reduction is counter by the advantageous gain in X-ray contrast, which, as has actually been illustrated, boosts with increasing quantities of additive.


PropertyTest MethodUnitsPEEK-OPTIMA UnfilledPEEK-OPTIMA Image contrast Grade (Low Radiopacity)PEEK-OPTIMA Image contrast Grade (High Radiopacity)
Tensile strengthISO 527MPa1009590
Tensile elongationISO 527%202015
Flexural modulusISO 178GPa43.84.5
Flexural strengthISO 178MPa170150150
Notched Izod impactISO 180kJ/m27.678
Specific gravityISO 1183g/cc1.31.361.49

As one alternative an approach to adding radiopaque powder, metallic wires (markers) may additionally be added to peek (particularly to peek composites) to do them clearly shows radiographically. This will be explained in an ext detail in ar 3.5.2.2, although that is, perhaps, appropriate to display a radiograph in this ar of this type of peek composite material. Number 3.11 compare the photo contrast achieved with CFR emergence (containing cable markers) through that for titanium and CFR peek (with no markers) under X-ray inspection.



A.G. Abel, in Paint and Surface Coatings (Second Edition), 1999

3.12.11.4 Barium sulphate (natural — barytes; synthetic — blanc fixe)

Colour index — Barytes, CI colours White 22; blanc fixe, CI colors White 21.

Formula — BaSO4.

Barium sulphate is really inert, insoluble and also stable come light and heat. The natural type is derived as the mineral ‘heavy spar’. After being crushed, washed and dried the is normally micronized, reducing its particle size indigenous 25 µm to 2–10 µm, hence aiding its dispersibility. The synthetic version is make by reacting accessible barium compounds through sulphuric mountain or soluble sulphate salts, and also has a finer texture 보다 the natural grades, offering it a higher oil absorption.

Its refractive index (1.64) is greater than other extenders, which provides it part pigmentary properties. The high thickness is also useful because that paints marketed by weight. That is provided in primers, undercoats, and also industrial finishes, wherein it hardens the film. Its high density leads come it having actually a propensity to settle. Regardless of it gift a barium salt, that insolubility ensures it is non-toxic.


Clive Maier, Teresa Calafut, in Polypropylene, 1998

4.3 Barite

Barium sulfate (Figure 4.3), typically called barite, is uncovered in the hydrothermal veins the cavity fissures in limestones, sandstone, shales, or clays or as surface ar deposits result from limestone weathering. Barite brightness depends on origin; brown buff barite (brightness 80–85) is uncovered in Nevada, Missouri, Georgia, Illinois, and Mexico, when pigment great white barite (brightness 92–94) is obtained almost exclusively from China. <942>

Barites space the most chemically resistant that the frequently used mineral in polypropylene (calcium carbonate, talc, mica, and also barite; Table 4.1), with excellent resistance come acids, alkali, and all recognized organic solvents. As result of a 60% higher specific gravity, loadings room low compared to other mineral fillers, and also the result on physics properties that the filled resin is not as pronounced. Barite has a high refractive index than other minerals. The is offered in heavier components or for applications that call for sound deadening or corrosion resistance. <942>


Andreas Höpe, in experimental Methods in the physics Sciences, 2014

6.6.2.2 BaSO4-Based Standards


John Murphy, in Additives for Plastics Handbook (Second Edition), 2001

7.1.3.2 Barium sulphate (‘blanc fixe’)

Precipitated barium sulphate (‘blanc fixe’) is an inert white filler, resistant come acid and alkalis, and also has very good weathering resistance. It does not absorb light from the ultraviolet to the infra-red variety and therefore does not impair the brilliance of colour pigments. Fragment sizes variety from 0.7 to 3.0 μm. Dispersability and also lack the grit are high: hardness and also stiffness of plastic are improved without result on surface high quality (especially gloss and also colour brilliance). It is also used to increase density and also X-ray opacity, specifically for toys and also medical articles, and also improves sound insulation values. Special qualities increase light scattering there is no absorption in semi-opaque link such together lampshades, PC and also PMMA sheets, and PVC film. Ultrafine particle grades (less 보다 0.2 μm) have been emerged as nucleating agents for partly crystallized thermoplastics.

Natural barium sulphates (barytes) are inert and also allow very high loadings: fine-particle qualities are wanted to rise the density of a plastics compound, if coarse corpuscle are far better for acoustic applications, specifically in automobiles.

Blanc fixe micro is a white inorganic powder because that plastics and also coatings, making up barium and also sulphate. It is nearly insoluble in water, necessary solvents, and acids/alkalis. That is produced from barytes, through removal of impurities, achieving a narrowly defined particle size distribution. Titanium dioxide production modern technology is supplied for finishing. Its particles are almost as fine as those of titanium dioxide pigments (barytes, 4 μm; synthetic barium sulphate, 3 μm; blanc fixe micro, 0.7 μm; titanium dioxide, 0.3 μm).

In use it is noteworthy for low binder replacement, ready dispersability, excessive fineness, short agglomerate content, and also (in coatings) high gloss. It can also act together a ‘spacer’ in between white or coloured pigments, possibly reducing titanium dioxide through 5–15%, or reducing colours costs, or raising solids content. Expense can be decreased by about 5% without detriment to properties.


W. Engewald, J. Pörschmann, in newspaper of chromatography Library, 1991

5.7.2 alteration With Non-porous Ionic Adsorbents

Disregarding barium sulphate, boron nitride and also molybdeneum disulphide, non-porous not natural adsorbents room rarely supplied in the pure kind as pillar packings. Their details surface area is low, and also so is your capacity. In stimulate to rise the surface area, they are coated ~ above silica gel, aluminium oxide or inert solid supports. About the chromatographic superiorities that (pure!) silica as form II adsorbents, us shall deal just with the change of this material. Specifically alkali and also alkaline-earth steel halides and also salts that the shift metals have actually been used as modifiers. They space coated top top the adsorbent as follows. An aqueous systems of the salt is blended with the silica gelatin whilst heating until the water has evaporated. In bespeak to acquire a homogeneous coverage, the mixture is heated come the melting suggest of the salt. It have the right to be assumed that a chemical reaction proceeds in between the surface silanol groups and the metal chlorides, forming a qualitatively new surface <561>, which is much more homogeneous 보다 the surface ar of the salt themselves.

Investigations by Scott <562> and Vidal-Madjar and also Guiochon <563> in this ar indicated that the modified adsorbents can interact specifically and charge-transfer interactions with π-electron systems take place. Varying the cations and also anions allows considerable mediate of the selectivity <564>. Adsorbents modified v BaCl2 (which has actually both Ba2+ and also Cl− ions on every faces and also on the surface) or through CoCl2 or NiCl2 (which exhibit a crystalline class structure and also faces and surfaces with greatly Cl− ions) in reality show differences in the specificity of the intermolecular interaction, however by modification with these three salts a an ext homogeneous surface ar is created, consist of preferentially the Cl∼ ions, independent of the vault crystalline structure <561>. Owing to the better specificity that BaCl2, the separation of butadiene indigenous the isomers that butane and butene have the right to be accomplished on BaCl2-modified Silochrom in ~ 50°C, conversely, CoCl2-modified Silochroms need a shaft temperature below room temperature <565>.


SaltAdsorbentApplicationReferences
LiCl, NaClSilica gelUnsaturated hydrocarbons, Organohalides aromatics<566>
KCl, CsCl, Na2SO4, LaCl3Silica gel, graphitized carbon blackUnsubstituted and haloge-nated aromatics<567, 568, 569>
NaCl, LaCl3, Na2 MoO4Silica gel, aluminium oxideInert gases<570>
NiCl2,CoCl2, BaCl2Silica gelIsomers of various families<565>
MgCl2, CoCl2, ZnCl2Silica gelAromatics<571>
LiF, NaF, KF, CsFAluminium oxideUnsaturated/saturated compounds<572>
Na3PO4Silica gelC1–C5 hydrocarbons within 2 min<568>

Complex link have likewise been made use of for editing and enhancing the surface. For example, (Ag pyridine2)NO3 interacts particularly with olefins <573>, and silica gels modified with tetram-minecopper(II) sulphate, copper(II)bisethylenediamine sulphate or copper(II)bistriethanol-amine sulphate are suitable for the separation of low-molecular-weight aliphatics and also aromatics <574>. Steel complexes of disubstituted organophosphorus acids have been used in the separation of compounds with π-electrons or heteroatoms <575>. Finally, it need to be spicy that steel complexes, similarly to salts and other modifiers, coated on an adsorbent execute not remove any type of heterogeneity completely but decrease the details adsorption energy and increase the specificity even at little layer thicknesses.


G. Crapper, in Polymer Science: A comprehensive Reference, 2012

10.29.4.3.5 Barium sulfate

Barium sulfate is extract from mined barites, and undergoes grinding and also classification to yield particles sizes suitable for usage in coatings.

As pointed out previously, barium sulfate has a greater specific gravity (ρ = 4.5 g cm−3), and hence leads to higher specific gravity coatings, or reduced coverage coatings (i.e., the coating consist of a lower area for a provided weight). The paint formulator should, therefore, only take into consideration barium sulfate once other possible fillers space not suitable, because that example, due to the negative acid resistance that calcium lead carbonate fillers.

Barium is a heavy metal and is toxic, and as such could be implicated in evaluations of powder coatings for suitability in finish uses whereby it might come into call with people and also animals. However, the short solubility the barium sulfate way that the product is no biologically available. Indeed, barium sulfate is supplied in medicine for ingestion to increase contrast in X-ray applications. Such debates lead the sector to think about barium sulfate as a nonhazardous filler.


1.

Formation of barium sulfate turbidity:i.Place a 100-mL sample (or a suitable section diluted to 100 mL) into a 250-mL Erlenmeyer flask.

ii.

Add specifically 5.0 mL conditioning reagent (See section:5.7.5).

iii.

Mix in the stirring apparatus.

iv.

While the systems is gift stirred, include a measure spoonful of BaCl2 crystals (See point 3 in section: 5.7.5) and begin timing immediately.

v.

Stir specifically 1.0 min at continuous speed.

2.

Measurement of barium sulfate turbidity:2.1Immediately after the stirring duration has ended, pour solution into absorbance cell.

2.2

Measure turbidity at 30-sec intervals for 4 min.

2.3

Record the best reading derived in the 4-min period.

3.

Preparation that calibration curve:3.1Prepare calibration curve using traditional sulfate equipment (see point 6 the “Reagent” section).

3.2

Maintain increment of standards at 5-mg/L in the 0–40 mg/L sulfate selection (Above 50 mg/L the accuracy decreases and also the suspensions shed stability).

3.3

Check dependability of calibration curve by running a standard through every three or 4 samples.

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4.

Calculations: calculation amount of SO42− from direct calibration curve, utilizing the complying with relation: