Preparation of Tungstic Acid
A Tungstic acid is an acid from a highly grained (fined grained) which is yellow in color and contains an awfully narrow grained size distribution (Yarwood, 2010). This acid always has a very high degree of the chemical purity of about 99 %. But this acid is highly reactive and is even morphology. Because of these distinctive nature of this acid, highly sensitive, special applications are possible areas like uniform fine chemistry, catalysis and the preparation of this tungstic metal of a given high quality and organometallic compounds of the Tungstic acid (Douthwaite, 2014). The figure below shows the powder which can be employed to manufacture or prepare the Tungstic Acid.
This Acid is also referred to as Tungstic (VI) Acid, Dihydrogen Wolframate tungsten. It has a chemical formula of H2WO4 or sometimes can be written as H2O4W. This acid always exists in a powder form and has a density of 5.5 g/mL at a temperature of the room which is 250 C (Jamwalo, 2013). This Acid referred to as hydrated forms of the tungstic trioxide WO3. The modest form, the monohydrate is WO3.H2O, The solid structure (powder) of WO3. H2O entail of layers of octahedrally coordinated WO5 (H2O) units which has four vertices are mutual or simply shared. And the dihydrate contains the same layers structure with the extra water (H2O) molecule inserted in between the layers (Enerst, 2015). The monohydrate is a yellow powder too but it is not soluble in water.
This acid can be classically referred to as “ Acid of Wolfram. “ This acid has a molecular mass of 249.85 g/mol, it is not soluble in water but highly soluble in ammonia and slightly soluble in ethanol. It has a density of 5.59g/cm3, it has a melting point of 1000C and boiling point of 14730C. Tungstic acid has a hydrogen Bond Donor of the count of four and a hydrogen Bond Accept Count of two (Davidson G., 2015).
To guarantee a justifiable amount of the raw material of this acid, a secondary source can also be employed as a secondary material (Ebsworth, 2012). In a highly erudite recycling process, a new highly pure tungstic acid yields from the materials which were used. There is also a chance for recycling the products which can be done by either reprocessing tungstic products or by buying recycled materials.
Tungstic Acid is a highly vague word used to refers to several solid prepared from the W (VI) solution with very strong Acids. Notwithstanding an extensive literature, there is obvious uncertainty as to the identity and chemical nature of this substance (Adams, 2010). The two compound H2WO4. H2O and H2WO4 have been categorized by x- rays diffraction and designated as acids and a similar precipitation can be identified as WO3. A third substance WO3/H2W2O7 can be got using H2WO4 with an alkaline solution. Limiting condition can be set for precipitation of a given compound are not determined and also the designation of the acid can be based on the thermal stability. For the soluble W(Vi) negative charges, it only the negative charges of Metangustate is adequately steady at a pH which is very low hence can be isolated as a free acid (Chenglong, 2017). The acid reactions of the precipitation of tungstic acid can hence be observed as a superficial occurrence.
Uses
This acid can be obtained through the action of a strong acid on solutions of metallic tungstate, this acid can also be prepared from the reaction which occurs between Sodium tungstate and hydrogen carbonate (Office, 2012). Tungstic Acid can be obtained also from a pure tungstic through a reaction between this tungstic and hydrogen peroxide. This acid is one of the simplest one to prepare since it is only prepared in the simple three ways as seen above.
Tungstic Acid is majorly employed as a dye in so many textile industries and it can as well be used as a mordant.
Properties of the Tungstic acid
The properties of Tungstic Acid can be discussed under three basic properties, these can be in
- Physical properties
- Chemical properties
Physical Properties
A tungstic acid is a yellow fined grained powder having a monohydrate (one molecule of water), as seen above, this acid has a density of 5.5 g/mL at a temperature of the room which is 250 C. It has a molecular mass of 249.85 g/mol (Voet, 2011). it has a melting point of 1000C and boiling point of 14730C. This acid has layers of octahedrally coordinated WO5 (H2O) units which has four vertices. Tungstic acid is an odorless powder. This acid is almost insoluble in many acids like sulfuric acid, nitric acid, hydrobromic acid, hydrochloric acid, dilute hydrogen periodate, it is slightly soluble in in hydrofluoric acid and it is highly soluble in ammonia and other alkali solutions like sodium hydroxide, calcium hydroxide (Zarina, 2011).
This acid is obtained from wolframite alkali fusion after hydrochloric decomposition of the system and it can also be obtained in the three ways discussed above, but the main source of this acid is from the Tungsten metal (James, 2015). Tungstic acid exists in amber, crystal ramps which can be grained into very fine grains. There is also another form of this acid where it can be in a white powder having two molecules of water (dehydrate) with a formula of WO3. 2H2O. both the yellow and this white acid can produce the same salt series (Lu, 2012). The first acid to appear during the preparation is the true acid of tungstic acid, H2WO4 (the yellow acid) while the second one is the hydrate having the formula H2WO4.H2O. But both are not soluble in water (Veenas, 2015). The white H2WO4. H2O is prepared by the decomposing the oxychlorides or the tungsten pentachloride in the availability of the moist air (Bhowmik, 2014). But both the yellow and the white have a melting point of 1000C to about 1100C where they lose water and left behind the composition of WO3. H2O the left residue does not appear to be a true hydrate on a continued heating WO3 is obtained After that heating the results indicate that between the dehydrate, WO3. 2H2O, and the anhydrous substance just one definite hydrate, WO3 .H2O will exist. And this result of the physical property of melting point can be highly supported by the help of x- rays examination (Edward, 2014). And both will exhibit a crystalline form when they contain the water molecules but powder form when the water of crystallization is evaporated away. And that why this yellow acid exists in powder form after evaporating its water molecule.
Properties of Tungstic Acid
Chemical properties of this tungstic acid simply deals with the how this acid is able to react with other substances, these reactions (chemical reactions) are discussed below;
Tungstic acid can be employed to catalyze the oxidation by peroxide of the organic compound (alkane) to the conforming epoxides (Freedman, 2013). This acid is a fairly strong acid the mixture reaction needs a buffering to avoid any subsequent formation of diol. The archetypal condition of this reaction includes the following: tungstic acid at 1 mol and 1 %, sodium acetate 2-3 mol at a pH of 4.5, hydrogen peroxide of 1.5 mol. Under the above typical conditions, the epoxidation takes place with a full retaining of configuration for both Tran- and cis-alkenes the reaction will increase with nucleophilicity of the double bond (Tallon, 2011). The coordination to the catalyst by the hydroxyl group in the substrate also enriches the epoxidation rate.
The unsaturated conjugated acid diacids epoxidized by the help of hydrogen peroxide and sodium tungstate in water at a temperature of about 600-650C having a pH control of about 5.8 to 6.8. The usage of paratungstate, W2O112- obtained from the tungstic acid and also from the chloride of benzyltriphenylphosphonium with a compound of formula Ph3PCH2Ph+ Cl–. The catalyst is made in a situ Tungstic acid can be employed to help catalyze the oxidation by the peroxide of hydrogen (hydrogen peroxide) of the sulfides to the conforming sulfones. Different amines have been oxidized too to the corresponding oximes, hydroxamic acid, nitroso compound and nitrones by the help of Tungstic acid (James F., 2012).
Tungstic Acid has electrophilic nature which enables it to be employed in the catalyzed trans-addition of the peroxide of hydrogen to an Olefin. One atom of the oxygen introduced by the tungstic acid catalyzed by hydroxylation (Ebsworth, 2012) Tungstic acid being an operational catalyst for the addition of hydroxide periodide to a linkage of ethylenic which yield a gives a high yield of the corresponding vicinal glycol. Some scientists like Mugdan and Young have proposed that the hydroxylation reaction comprises 1,2-trans-addition of a middle peroxy acid. For the double bonds additions of the two hydroxyl categories proceeds in the trans-direction. And the following mechanism was proposed by the Mugdan and young;
Derivatives with the hydrogen peroxide tungstic acid system and direct hydroxylation of fats.
Tungstic acid can be combined with hydrogen peroxide and used for direct hydroxylation of fat and derivatives. The direct preparation of threo -1,2-glycols minus the isolation of the intermediary from methyl oleate, oleic acid and oleyl alcohol by oxidation by the help of tungstic acid system at 45 to 55 C and hydrogen peroxide of 70% minus the solvent has now been proved to be efficient, reaction of high yield. The three- isomers are made from the intermediary epoxides by in a hydration situ with associated inversion (Hassan, 2011). The incorporation of 2 % of the reaction of the glycol product into the methyl oleate or the oleic acid, this will help to speeds up the chemical reaction adds and also markedly to their reproducibility Emulsion are readily oxidized in some special conditions, but these schemes are more complex to make and work up than it is for the oxidation of the substrate unswervingly (Wyman, 2010). Timid reaction techniques are suggested in which an organic polyperoxytungstic acid is an operational oxidizing agent.
Chemical Properties
A reaction where a pure tungstic acid is produced from impure alkali metal tungstate.
A tungstic acid can be produced from acidification of impure alkali or molybdate or ammonium tungstate. This scheme is less expensive than to employ the use of the hydrochloric acid or by use of sulfuric acid and it helps to prevent impurity of chloride for this reason ammonium tungstate, molybdate solutions are not preferred to hydrochloric acid and sulfuric acid. A tungsten material like a tungsten metal ore is decomposed by the help of a solution of caustic soda to get an impure sodium tungstate solution (Na2WO4), the pH of the solution will be at around 13-14 (Commission, 2012). The impurities like silicon, phosphorous and arsenic ions. In the first step in the purification, the Na2WO4 solution is acidified to a pH of 9 with an initially made sodium metatungstate. The quantity of sodium metatungstate to be put will depend on the quantity of the impurities available and it is chosen in a way that the pH value of the generated an optimum hydrolysis (precipitation) of the ions to be detached (Gmelin, 2012).
The Na5HW6O21 appears to occur as (Na) +5 (HW6O21-5). In other terms hydrogen in the salt is not ionized, during the reaction this salt is capable to bind sodium ions, but according to the formula, when the hydrogen is soluble only one sodium may be blind. It is more amazing and not at all clear for those of normal skills in the art of that the polymers of this form will as well react with the monomer salt (X) Na2 WO4 and a polymer (Y) Na5 HW6 O2. For instance; for one liter solution having 104g/l tungsten (WO4 -2), about 43 g/l solution, 1.8 g/l of silica ( SiO2), 0.3 g/l arsenic ( ASO4– ), and 0.5 g/l phosphorous ( PO4-3) can be added to one liter of the (Al2SO2)3 aluminum sulfate at a concentration of about 80g/l and also 30 ml of the magnesium sulfate (MgSO4) at a concentration of roughly 300g/l.
A reaction which involves recuperating tungstic acid values from the aqueous compound.
The word tungstic acid is employed in this chemical reaction to define tungstic acid as a catalyst chemical whatsoever its particular form it may take (Christian, 2014). In the process of the organic epoxidation encompassing the use of peroxide of hydrogen and the tungstic acid. In the elution from an ion-exchanged bed, the acid atom O ice catalyst occurs as the water dissolve the sodium tungstate. Except as hereinafter several particularly distinct either in its solubility in water or simply in terms of its actual chemical properties.
Recovery of this acid as a catalyst through this invention is of overall applicability irrespective of a specific organic oxidation process where the catalyst is used. Apparently, techniques of handling the particular chemical forms of any of the several oxidations through using this catalyst. This is always determined best by a condition most appropriate to a given reaction of oxidation. The interest to separate the products which are oxidized prior to recovering this acid values will actually be pegged on a bigger degree of the steadiness of the products which are oxidized in some beneficial conditions to the tungstic acid catalyst recovery (Washington, 2013).
Epoxidation of Alkenes
This can be easily fathomed that the available in the contemplates vention the processing of the medium of the reaction in a way reliable with the suitable recovery of the oxidation products produced during the reactions while taking in to account the specific techniques of tungstic value recovery. In combination with the oxidation leading to epoxide separation of the product erstwhile to the recovery of the catalyst may be utmost anticipated specifically when the epoxide inclines to decompose to other products in the same reaction conditions of the catalyst recovery.
The molecular formula structure of the tungstic acid, it is therefore clear that the unit cell of the tungstic acid is the W (wolfram), two atoms of Hydrogen (H2) and four atoms of Oxygen (O4). The main component of this acid is treated to be Wolfram since this acid is basically prepared from the Wolfram acid.
Ultra Violet (UV) radiation basically is applied in the tungstic acid in it’s a preparation stage. The monodispersed tungstic acid which is a nanoparticle solid having a mean diameter of about 20 nanometers ( nm) can be made by using this ultraviolet light radiation of oxotungsten citrate complicated aqueous solution. The outcomes from the Infrared spectroscopy indicates that the oxotungsten citation complex decomposes firstly to form a citric acid and tungstic acid under the radiations of the UV light (White, 2012). Thereafter the citric acid will undergo a photodegradation in a tungstic acid catalysis.
The XRD outcome of this UV on tungstic acid may indicate that the attained product may consist of the WO3. H2O and WO3. 2H2O. The time is taken to during the radiation known as the irradiation time and the ratio of molar of the citric acid to that of the sodium tungstate will have a very vital effect on the composition of the product. The prolonging time of radiation the amount of the WO3.2 H2O in the whole substance will reduce but that for the WO3.H2O will increase. For the particle size, it will increase and the size of the distribution will definitely widen. Moreover, the size of the particles decreases and the distribution becomes very narrow. The figure below shows the UV radiation in the preparation stages of the tungstic acid.
The Nanocrystalline powders of the tungstic acid are prepared in a very controlled chemical technique. The structure of the acid and its characteristics of the vibration can be obtained from the Raman and the XRD spectroscopy (Acton, 2012). The X-ray phenomenon of the Spectroscopy (XPS) scrutiny of the sample shows the availability of the oxygen vacancies that always confirm the UV photoluminescence (PL) and absorption-emission workings. The figure below shows the photoluminescence (PL) spectrum;
Depending on how the UV radiation is employed, the UV radiation can as well be employed to prepare WO3 (Tungstate) from the tungstic acid. In this scheme, the WO3 catalytic powder is successfully prepared from the tungstic acid. In this case, sodium tungstate is used too. The wo3 process of crystallization is achieved by calcination of samples at a high temperature of about 5000C to 7000C. The activity of the photocatalytic of the tungstate WO3 sample can be evaluated through discoloration efficiency of the MB ( methalyne Blue).
And this heterogonous photocatalysis is actually very vital as it can be employed degradation pollutant of water, and in most cases, it is referred to as a green technology for the treatment of almost all type of the contaminants, for example removing organic dyes having very complex structures (molecular structure). And this is usually available in wastewater from any textile industry.
Infrared is a region of the spectrum, hence it is very vital in the spectral graph during the preparation of the tungstic acid, hence it helps doing the analysis of the acid produced (Wong-Ng, 2015). The tungstic acid catalyst is prepared through a very simple ways based on a reaction of SOCI2 (silica), this is immediately followed by putting sodium tungstate in the silica then the mixture is functionalized by the help of chlorosulfonic acid (Ohktata, 2016). The catalyst accepts different heteroaldehydes and is also catalyzed the creation of a compound known as Biginelli yielding an excellent products. The catalyst is categorized by the Infrared analyses (Conington, 2013). With the help of the IR, the analysis of this catalyst is realized and becomes so easy and simple as compared to a scenario without the IR or other ways of doing the analysis like XRD, SEM-EDX.
This is an individual who believes that a disaster or an emergency can easily occur in some future times and he can make some serious preparations to help prevent the situation from occurring. The prepper for tungstic acid is basically those who in most cases interacts with this acid. Therefore prepper for tungstic acid is properly those who work in the textile industry, those who manufacture the acid and those who work in the company that deals with dye apart from the textile industry (Staff, 2012). Since the tungstic acid has some health effects, the preppers need to come up some techniques or ways or minimizing the risks which may arise due to this acid. These risks are discussed below;
Eye contact: This acid is highly dangerous when it gets in contact with eyes, and it can cause blindness depending on the amount that gets in contact. So the prepper will ensure that all the contacts of the acid are in good condition to help avoid any contact with the eye. But by a chance of the contact into the human’s eye, then it is highly advisable that the victim should wash his or her eyes with a lot of water for about 15 minutes. He should then seek medical attention if there are irritation witnessed.
Skin cancer: The prepper should ensure that any individual interacts with this tungstic acid put on gloves, dust coat, boats among other protective clothes. If by any chance the acid get in contact with the acid then the part must be thoroughly washed with soap and water and then covered with an emollient, but if irritation develops then the victims should visit the hospital immediately
Inhalation: The prepper should ensure that this acid is highly covered to prevent it from being inhaled by the individual working around it. When this acid is inhaled it will make it very difficult to breathe. So if this acid is inhaled then the victim should be given oxygen through the inhaler ( artificial respiration ).
Flammability: This acid is nonflammable therefore it will not cause any risk or accident through fire.
Ingestion: any individual who interacts with this acid should not induce vomiting not only when they are directed to so by the medical officer. Nothing should be given by the mouth to any unconscious person. When a large material of this acid is swallowed then the prepper should help the victim to lossen the tight clothes like the tie, collar, waistband, and belts and call the physician immediately.
Small spill: The prepper needs to ensure that they employ the use of a suitable tool to put the solid which has spilled in an appropriate container for waste disposal. In some case, the neutralization reaction is done with the alkalis like sodium carbonate. The cleaning is done through spreading water to all the surfaces which are contaminated (Jamwalo, 2013).
References
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