TWI503282B - Method for preparing molybdenum oxide powder in molybdenum waste liquid - Google Patents

Description

Method for preparing molybdenum oxide powder in molybdenum acid waste liquid

The present invention relates to the treatment technology of molybdic acid waste liquid, and more specifically to a method for preparing molybdenum oxide powder in a molybdenum acid waste liquid.

Molybdenum (Mo) is a kind of rare heavy metal with high melting point, high hardness, good wear resistance, good thermal conductivity, small thermal expansion coefficient and good corrosion resistance. Therefore, it is widely used in various industries such as metallurgy, petroleum, chemical, electronics, optoelectronics, etc. For example, it can be used as an alloying element of steel (to increase the hardness of steel), and as a catalyst for the petrochemical industry to assist in the removal of specific impurities (such as metals such as sulfur, nitrogen, vanadium, and nickel). Its oxide-----molybdenum oxide (molybdenum trioxide, MoO ₃ ), usually exists in the form of polycrystals, such as thermal stable phase (α-MoO ₃ ), metastable phase (β-MoO ₃ ) and six Angular molybdenum trioxide (h-MoO ₃ ), in which a thermally stable phase (α-MoO _{3 has} a wide range of applications due to its excellent properties, such as field emitters, optical components, thermoelectric materials, catalysts, sensations Detectors, lubricants, electrochemical memories, etc. Therefore, the wastewater of the aforementioned type of industry often contains molybdenum components, which are usually in the form of molybdate (such as ammonium molybdate (NH ₄ ) ₂ MoO ₄ , molybdenum Sodium Na ₂ MoO ₄ ).

Secondly, heavy metal ions in industrial wastewater are pollutants that are extremely harmful to the ecological environment. After entering the environment, they cannot be biodegraded and will pass through the food. The chain of matter accumulates in the organism, thereby destroying the normal physiological activities of the organism. Therefore, how to effectively treat heavy metal ion wastewater and recover metal ions has become an important issue in the field of environmental protection.

Based on the fact that molybdenum is such a widely used metal and its rarity, the recovery of molybdenum from industrial wastewater clearly has its commercial value and environmental benefits. Conventional techniques for recovering molybdenum components in industrial wastewater include ion exchange resins, sol-gel methods, and chemical precipitation methods such as nitric acid deposition. The ion exchange resin method mainly utilizes the exchange of isotropic ions and heavy metal ions on the ion exchange resin to remove the metal ions from the waste water, and is currently the most important application method for recovering molybdenum, however, the resin is easily oxidized and contaminated. The high requirement for pretreatment is its disadvantage. Furthermore, the material and operating costs are higher when compared to the chemical precipitation method, especially for the treatment of a large amount of low-concentration heavy metal ion wastewater.

The main object of the present invention is to provide a method for preparing molybdenum oxide powder in a molybdenum acid waste liquid, which can be obtained by adding an alcohol solution to a molybdenum acid waste liquid for mixing, centrifuging, washing, drying, grinding and heat treatment. Molybdenum oxide powder is easy to implement and control, and it is very practical.

In order to achieve the foregoing objective, the present invention provides a method for preparing molybdenum oxide in a waste liquid of molybdic acid, the steps of which at least include: a) adding an appropriate amount of an alcohol solution to a molybdenum acid waste liquid, and stirring and mixing; b) the previous steps The mixture is heated at a predetermined temperature to produce a deep blue solution and a precipitate; c) the aforementioned dark blue solution and the precipitate are cooled; d) the dark blue solution and the precipitate are separated by centrifugation; e) the precipitate is washed with distilled water ; f) drying the precipitate after washing to obtain a cake of molybdenum oxide hydrate; g) grinding the molybdenum oxide hydrate block and heat-treating to obtain α-molybdenum oxide powder.

Method for preparing molybdenum oxide in 100‧‧‧ molybdenum acid waste liquid

110‧‧‧Add an appropriate amount of alcohol solution to the molybdenum-containing waste liquid and mix and mix

120‧‧‧ Heating the mixture of the previous step at a predetermined temperature to produce a dark blue solution and precipitate

130‧‧‧Cooling the aforementioned dark blue solution and sediment

140‧‧‧Separation of dark blue solution and sediment by centrifugation

150‧‧‧Clean the sediment with distilled water

160‧‧‧Dry the washed precipitate to obtain a block of molybdenum oxide hydrate

170‧‧‧The molybdenum oxide hydrate block was ground to a powder

180‧‧‧ Heat treatment of the aforementioned powder to obtain molybdenum oxide powder

1 is a flow chart of a preferred embodiment of the present invention.

Figure 2 is a graph showing the ethylene glycol content-time relationship of a preferred embodiment of the present invention.

Figure 3 is an energy spectrum diagram of a preferred embodiment of the present invention showing a peak change in intensity (a.u.) versus angle (2?).

Figures 4(a) and (b) are diagrams showing the binding energy-intensity relationship of a preferred embodiment of the present invention.

Hereinafter, some preferred embodiments of the present invention will be described in detail with reference to the drawings. First, as shown in FIG. 1, a method for preparing molybdenum oxide in a molybdenum acid waste liquid according to a preferred embodiment of the present invention is shown in FIG. For recovering molybdenum (Mo) metal components in industrial waste liquid containing molybdic acid (such as sodium molybdate, Na ₂ MoO ₄ and ammonium molybdate, (NH ₄ ) ₂ MoO ₄ ), the first step 110 will be Add an appropriate amount of alcohol (ethylene glycol) solution to the molybdenum acid-containing waste liquid and mix and mix: the ratio of the alcohol solution to the ratio of 1 to 3 and the industrial waste liquid is about 5, for example, 20 ml of ethylene glycol. Mix 50 ml of industrial wastewater (containing 8131 ppm of molybdic acid) and place it in any tank or beaker and stir it.

In the second step 120 of the present invention, the mixture of the previous step is heated at a predetermined temperature to produce a dark blue solution and a precipitate: the mixture of the alcohol solution and the industrial waste liquid is heated at a temperature of 120 ° C for 40 minutes to be produced. Precipitate and dark blue solution.

The third step 130 of the present invention cools the aforementioned dark blue solution and precipitate.

The fourth step 140 of the present invention separates the dark blue solution and the precipitate by centrifugation: the dark blue solution and the precipitate are placed in a centrifuge tube of the centrifugal device for 2 to 3 times, each time for 15 minutes of centrifugation. The rotation speed of the centrifugal device is 4000~5000 rpm. After the solution is separated from the sediment, the wastewater is placed in a glass bottle for subsequent determination of the molybdic acid content with the raw liquid.

In the fifth step 150 of the present invention, the precipitate is washed with distilled water: the precipitate separated in the foregoing step is washed with distilled water to remove residual liquid.

The sixth step 160 of the present invention is to dry the washed precipitate to obtain a block of molybdenum oxide hydrate: the precipitate is placed in a petri dish and placed in an oven at a temperature of 80 to 100 ° C. After baking for 24 hours, a white molybdenum oxide hydrate (MoO ₃ .H ₂ O) cake was obtained.

The seventh step 170 of the present invention is a molybdenum oxide hydrate block The material was ground to a powder.

In the final step 180 of the present invention, the foregoing powder is heat-treated at 300 ° C for 1 hour to obtain a gray α-molybdenum oxide powder.

Hereinafter, the correlation analysis and verification of the α-molybdenum oxide powder prepared by the method of the present invention and the wastewater are as follows:

1. The effect of reaction time:

As shown in the photograph of Annex I and Table 1, the process of the method of the present invention, the molybdic acid wastewater will change color with the increase of reaction time, and the sequence of color change is yellow orange→yellow→green yellow→light blue Color→dark blue, the reaction time of molybdic acid wastewater changing to dark blue is 1742 seconds, which shows that when the molybdenum acid in the wastewater decreases, the color approaches dark blue, and the pH value of molybdic acid wastewater decreases with the increase of reaction time. It decreased from pH 1.1 to less than 1, indicating that molybdate ion (MoO ₄ ^-2 ) was formed and produced more acid during the reaction, while the concentration of Mo ion in molybdic acid wastewater decreased from 8131 ppm to 1506 ppm, indicating that the original molybdenum More than 69.5% of the Mo ions in the acid wastewater have been reacted.

Table 1:

Oxidation to acetic acid, as shown in Equations 1, 2. The acetic acid produced is decomposed into acetate ions (CH ₃ COO ^- ) and hydrogen ions (H ⁺ ) as shown in Equation 3. Other alcohol solutions such as 1,2-pentanediol are oxidized to 1,2-pentanal and then oxidized to 1,2-pentanoic acid, 1,3-butanediol is oxidized to 1,3-butyraldehyde and then oxidized to 1 3-butyric acid and 1,4-butanediol are oxidized to 1,4-butyraldehyde and then oxidized to 1,4-butyric acid, tripropylene glycol methyl ether oxidized to tripropionaldehyde methyl ether and then oxidized to tripropionaldehyde. The molybdenum acid waste liquid is converted into hydronium ion (H ₃ O ⁺ ) and molybdate ion (MoO ₄ ^-2 ) as shown in Equation 4. Then, molybdate ions (MoO ₄ ^-2 ) are reacted with hydrogen ions (H ⁺ ) to form molybdenum oxide hydrate (MoO ₃ .H ₂ O) as shown in Equations 5 and 6.

2CH ₂ OHCH ₂ OH+O ₂ → 2CH ₃ CHO+2H ₂ O (1)

2CH ₃ CHO+O ₂ → CH ₃ COOH+2H ₂ O (2)

CH ₃ COOH → CH ₃ COO ^- +H ⁺ (3)

H ₂ MoO ₄ +2H ₂ O → 2H ₃ O ⁺ +MoO ₄ ^-2 (4)

MoO ₄ ^-2 +H ⁺ → HO(MoO ₃ ) ^- (5)

HO(MoO ₃ ) ^- +H ⁺ → (H ₂ -O)-(MoO ₃ ) → MoO ₃ . H ₂ O (6)

2. Effect of reactant content:

50 ml of molybdenum acid waste liquid is mixed with different contents (such as 10, 20, 30, 40 and 50 ml) of alcohol (reactant, ethylene glycol) and heated to 120 ° C. The time of blue product generation is The increase in alcohol content increases as shown in Figure 2. The experimental results give the equation Y = 0.32X + 32, Y is the time required to produce a blue product, and X is the amount of reactant used. This equation can provide the time required to produce a blue product when the amount of reactant changes.

Table 2 shows the concentration of residual molybdenum ions in the solution and the recovery of Mo after the reaction of different alcohols with molybdenum acid waste. The recovery of Mo (R) is as follows: R(%)=([Mo] _o - [Mo] _f )/[Mo] _o ×100, (7)

[Mo] _o in the above formula refers to the content of initial Mo ions in the waste liquid, and [Mo] _f refers to the content of Mo ions after the white product produced in the reaction process is removed.

As can be seen from Table 2, when 50 ml of the molybdenum acid waste liquid was reacted with 20 ml of an alcohol (ethylene glycol) at 120 ° C for 40 minutes, the maximum recovery of molybdenum ions was 69.5%. When the alcohol content is increased to 30 ml, the recovery rate is reduced to 20%, and when the alcohol content is increased to 40 ml or more, the recovery rate is 0, and the color change of the wastewater is dark blue, but no precipitate is generated. The reason is mainly because the addition of excess alcohol during the reaction hinders the reaction of molybdenum ions, and the temperature of the reaction must be raised to allow the reaction to produce precipitates.

3. Powder characteristics:

As shown in Annexes (a) and (b), the SEM images before and after the powder heat treatment. The particles of the powder before the heat treatment are rectangular, and the corners of the rectangular particles are smooth after heat treatment. The structure is analyzed by X-ray diffraction (XRD), infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS): Heat treated powder with XRD peaks at 2θ = 12.4°, 13.7°, 14.9°, 18.6°, 22°, 24.8°, 27°, 28.1°, 30.3° and 37.7°, with commercial molybdenum oxide hydrate (MoO) The peak of ₃ .H ₂ O) matches. However, the same sample composition data cannot be obtained from the powder crystal diffraction card (JCPDS). Therefore, it is presumed that this white powder is molybdenum oxide hydrate (MoO ₃ .H ₂ O). Annex III (a) is a transmission electron microscope (TEM) image of a molybdenum oxide hydrate (MoO ₃ .H ₂ O) powder, which shows that the powder contains both amorphous and crystalline regions. (b) and (c) show the selected area electronic diffraction (SAED) pattern. (d) The graph shows a high resolution transmission electron microscope (HRTEM) pattern of lattice fringes of the crystalline region. When the powder is heat treated at 300 ° C, its crystallinity and peak value are in accordance with the value of JCPDS database No. 05-0508 of molybdenum trioxide, as shown in Figure 3. In the range of 2θ=12.7°, 23.3°, 25.7°, 27.3°, 33.6°, 38.9°, 45.8°, 46.3°, 49.2°, 55.2°, 56.3°, 58.8° and 64.6°, in accordance with α-MoO ₃ The orthogonal phase, and the crystal plane (020) is clearly detected at 2θ = 12.74 °, indicating that the powder is an orthogonal phase rather than a monoclinic phase. In addition, the crystal faces (110), (040), (021), (111), and (060) conform to the symmetry of the tetragonal crystal. According to the value of the JCPDS database number 05-0508, the formula of the interplanar spacing from the orthogonal phase, The calculated lattice parameters (Å) are a = 3.96, b = 13.86, and c = 3.70, respectively. Therefore, when the molybdenum oxide powder is heat-treated at 300 ° C, α-molybdenum trioxide (α-MoO ₃ , MoO ₃ .H ₂ O+O ₂ → α-MoO ₃ ) can be formed, and the result can also be obtained by using a transmission electron microscope. The results of (TEM) are proved.

As shown in the crystal diffraction diagram of Annex IV (a), the α-molybdenum oxide powder produced by the white powder after heat treatment at 300 ° C for 1 hour, the crystal preferentially grows along the c-axis or [010] direction, showing molybdenum oxide powder. (Single grain) has good crystallinity. This phenomenon can also be confirmed from X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) results that the powder has high crystallinity. As shown in Annex IV (b), the lattice fringes in the HRTEM image show that the lattice fringe length on the single crystal structure is 0.39 nm (100 faces of α-MoO ₃ ) and 0.36 nm (001 of α-MoO ₃ , respectively). The surface can thus prove that the powder is a single crystal structure.

The chemical composition of the unheated and heat treated powder was measured by XPS spectrometer. The results show that the peaks of Mo 3d _5/2 and Mo 3d _3/2 of the unheated powder are located at positions of 232.33 eV and 235.33 eV, respectively, as shown in Fig. 4 (a). The spin-orbit separation between the peaks of Mo 3d _5/2 and Mo 3d _3/2 was 3.2 eV, and the full width at half maximum (FWHM) was 1.57 and 1.42 eV, respectively. The peak area ratio of Mo 3d _5/2 to Mo 3d _3/2 was 2.33. The peaks of Mo 3d _5/2 and Mo 3d _3/2 obtained after heat treatment of the powder through 300 ° C are located at positions 233.76 eV and 237.03 eV, respectively, and almost coincide with Mo 3d _5/2 and Mo 3d _{3/2 of} α-MoO ₃ . The peak value is 233.15 eV and 236.28 eV. The energy separation between the peaks of Mo 3d _5/2 and Mo 3d _3/2 was measured to be 3.27 eV, and the full width at half maximum (FWHM) was 1.41 and 1.41 eV, respectively, Mo 3d _5/2 and Mo 3d _3/2. The peak area ratio is 1.89.

Figure 4 (b) shows the peak of O 1s of the XPS spectrum of the powder structure. The O 1s peak of O-Mo of the unheated powder was 530.57 eV. Heat treated 300 ℃, 1 h, the powder O ₂ ^- peak 532.19eV, here O ₂ ^- is an oxygen defect regions (oxygen-deficient regions), therefore, may be demonstrated in the MoO ₃ α-MoO ₃ structure having oxygen vacancies Structure.

4. Effects of other alcohol types

The aforementioned alcohols can be reacted with molybdenum acid waste liquid to form molybdenum oxide powder, and other alcohols such as 1,2-pentanediol, 1,3-butanediol, 1,4-butanediol and tripropylene glycol. Methyl ether can also be mixed with molybdic acid waste liquid to react at 120 ° C. 40 Molybdenum oxide hydrates of different shapes are obtained in minutes, as shown in Table 3 and Annex 5. Annex V (a) is a molybdenum oxide hydrate powder formed by reacting 1,2-pentanediol with a molybdic acid solution. The powder is in the form of a strip of molybdenum oxide hydrate powder prepared in the form of a strip and having a size smaller than that of ethylene glycol. Annex II) is still large. Although 1,2-pentanediol has a long carbon chain, one of the structures in the structure is bonded to the second carbon chain, which hinders the growth of molybdenum oxide. Larger size. Annexes (b) and (c) are molybdenum oxide hydrate powders formed by reacting 1,3-butanediol, 1,4-butanediol and molybdic acid waste liquid, respectively, and the powder shape is also elongated, but The size is smaller than that of the molybdenum oxide hydrate powder prepared from ethylene glycol and 1,2-pentanediol. The main reason is that 1,3-butanediol and 1,4-butanediol have longer carbon chains, affecting Formation of molybdenum oxide.

Annex V (d) is a molybdenum oxide hydrate powder formed by the reaction of tripropylene glycol methyl ether with molybdic acid waste liquid. Due to the chemical structure of two oxygen groups, the formation of molybdenum oxide is hindered, and the powder shape is irregular. And have a larger size. In addition, Annex VI is an SEM image of heat-treated molybdenum powder prepared by different alcohols at 300 ° C for 1 hour, which are (a) 1,2-pentanediol (b) 1,3-butanediol (c) 1, 4-butanediol (d) tripropylene glycol methyl ether. The shape of the formed powder has a rounded corner and a small size.

It can be seen from the above that the present invention utilizes the steps of mixing, centrifuging, washing, drying, grinding and heat-treating the alcohol solution into the molybdenum acid waste liquid to obtain the molybdenum oxide powder, and analyzing and confirming the powder through various instruments. It is an orthorhombic molybdenum trioxide (α-MoO ₃ ). Secondly, the present invention is very easy to implement and control, and can be widely applied to remove heavy metals from waste water, and has practical value. The reason is that the present invention does meet the requirements of the invention patent, and the application is made according to law.

Method for preparing molybdenum oxide in 100‧‧‧ molybdenum acid waste liquid

110‧‧‧Add an appropriate amount of alcohol solution to the molybdenum-containing waste liquid and mix and mix

120‧‧‧ Heating the mixture of the previous step at a predetermined temperature to produce a dark blue solution and precipitate

130‧‧‧Cooling the aforementioned dark blue solution and sediment

140‧‧‧Separation of dark blue solution and sediment by centrifugation

150‧‧‧Clean the sediment with distilled water

160‧‧‧Dry the washed precipitate to obtain a block of molybdenum oxide hydrate

170‧‧‧The molybdenum oxide hydrate block was ground to a powder

180‧‧‧ Heat treatment of the aforementioned powder to obtain molybdenum oxide powder

Claims (5)

A method for preparing molybdenum oxide in a waste liquid of molybdic acid, the steps comprising at least: a) adding an alcohol solution to a molybdenum acid waste liquid, and stirring and mixing, the ratio of the alcohol solution to the molybdenum acid waste liquid is about 1 ~3:5; b) heating the mixture of the previous step at a temperature of 120 ° C for 40 minutes to produce a dark blue solution and precipitate; c) cooling the aforementioned dark blue solution and precipitate to room temperature; d) using centrifugation The method is as follows: separating the dark blue solution from the precipitate; e) washing the precipitate with distilled water; f) drying the washed precipitate to obtain a block of molybdenum oxide hydrate, and the precipitate after washing is 80 Heating at -100 ° C for 24 hours; g) grinding the molybdenum oxide hydrate mass into a powder; and h) heating the previously released molybdenum oxide hydrate powder at 300 ° C for 1 hour to obtain a gray α-molybdenum oxide powder. The method for preparing molybdenum oxide in the molybdenum acid waste liquid according to claim 1, wherein in the step a), the alcohol solution may be 1,2-pentanediol, 1,3-butanediol, 1 One of 4-butanediol or tripropylene glycol methyl ether. The method for preparing molybdenum oxide in the molybdenum acid waste liquid according to the first aspect of the patent application, wherein, in the step b), the maximum recovery rate of the molybdenum ions is 69.5%. The method for preparing molybdenum oxide in the molybdenum acid waste liquid according to claim 1, wherein in the step d), the dark blue solution and the precipitate are placed in a centrifuge tube of a centrifugal device to perform a centrifugation process. The method for preparing molybdenum oxide in the molybdenum acid waste liquid according to the fourth aspect of the patent application, wherein in the step d), the centrifugation is carried out 2 to 3 times, and the centrifugation program is performed for 15 minutes each time, and the rotation speed of the centrifugal device is 4000. ~5000 rpm.