Method for quantitatively analyzing residual Cl in zinc ferrite

Abstract

The present invention relates to a method for quantitatively analyzing Cl, remaining after synthesis, in zinc ferrite synthesized using chloride precursors such as zinc chloride and iron chloride, and provides a method capable of using, in a quantitative analysis method of Cl remaining after synthesis of an inorganic material, AQF-IC, which has been used only in the quantitative analysis of an organic sample since gaseous Cl, discharged after burning zinc ferrite in an automatic quick furnace (AQF) by using an Sn capsule and tungsten oxide (WO3), is analyzed through ion chromatography (IC).

Claims

1. A method for quantitative analysis of residual Cl in synthesized zinc ferrite, comprising: introducing a sample of zinc ferrite synthesized from a chloride precursor into a Sn capsule to produce an Sn capsule containing the sample; then, continuously transferring the Sn capsule containing the samples, along with tungsten oxide (WO.sub.3), into an automatic quick furnace (AQF) pretreatment apparatus heated at a high temperature; combusting the Sn capsule containing the sample in the AQF pretreatment apparatus; collecting gaseous Cl released by the combustion in the AQF pretreatment apparatus in an absorbing solution; and injecting the absorbing solution in which gaseous Cl has been collected into an ion chromatography (IC) device, and then quantifying a Cl content.

2. The method for quantitative analysis according to claim 1, wherein the chloride precursor is zinc chloride or iron chloride.

3. The method for quantitative analysis according to claim 1, wherein the sample is transferred into the AQF pretreatment apparatus for less than 10 seconds.

4. The method for quantitative analysis according to claim 1, wherein the combustion is carried out at a temperature of 1,000° C. or higher.

5. The method for quantitative analysis according to claim 1, wherein the absorbing solution is a solution of H.sub.2O: H.sub.2O.sub.2=300:1 to 350:1 (volume ratio).

6. The method for quantitative analysis according to claim 1, wherein WO.sub.3 is a combustion improver that causes complete combustion during the sample combustion.

7. The method for quantitative analysis according to claim 4, wherein a maximum combustion temperature is about 2,000° C.

8. The method for quantitative analysis according to claim 5, wherein the absorbing solution is a solution of 500 mL of H.sub.2O and 1.5 mL of H.sub.2O.sub.2.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic diagram of an example of an AQF device.

DETAILED DESCRIPTION OF THE INVENTION

(2) The present invention may be subject to various modifications and may have various embodiments, and specific embodiments are to be exemplified and described in detail. It is to be understood, however, that the intention is not to limit the invention to the particular embodiments, but to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. In the following description of the present invention, detailed description of known functions will be omitted if it is determined that it may obscure the gist of the present invention.

(3) As described above, in the prior art, quantitative analyses of residual CI in synthesized inorganic materials could not be completely performed. Therefore, the present invention attempts ion chromatography analysis by using AQF pretreatment apparatus applied for solid organic material samples in order to quantitatively analyze residual Cl in zinc ferrite synthesized from chloride precursors such as zinc chloride, iron chloride, etc. as inorganic materials. As a result, the present invention achieves quantitative analyse of residual Cl in synthesized inorganic materials by applying IC device equipped with AQF pretreatment apparatus, which is generally used only for quantitative analyses of organic materials, by burning zinc ferrite contained in Sn capsules together with WO.sub.3.

(4) Specifically, the present invention provides, as an embodiment,

(5) a method for quantitative analysis of residual Cl in synthesized zinc ferrite, which comprises

(6) introducing zinc ferrite samples synthesized from chloride precursors such as zinc chloride, iron chloride, etc., into Sn capsules, and then continuously transferring the samples with tungsten oxide into an automatic quick furnace (AQF) pretreatment apparatus heated at a high temperature;

(7) burning the Sn capsules comprising the samples;

(8) collecting gaseous Cl released by the combustion in the AQF pretreatment apparatus in an absorbing solution; and

(9) injecting the absorbing solution in which gaseous Cl has been collected into an ion chromatography (IC), and then quantifying the Cl content.

(10) According to one embodiment of the present invention, AQF pretreatment apparatus of Mitsubishi Chemical Analytech Co., Ltd. which has been used for organic solid samples may be used. According to one embodiment, the AQF may have a heating furnace made of gypsum, and a quartz glass tube may be present as a combustion tube passing through the furnace. The length of the quartz glass tube may be about 40 cm, and the sample may be heated at a point about 16 cm, which is the center part of the quartz glass tube. A part of the glass tube at the starting point and a part of the glass tube at the end point may be out of the heating furnace, about 30 cm length of the glass tube may be present in the heating furnace.

(11) The AQF pretreatment apparatus may raise the combustion temperature up to 1,000° C. at the maximum. When Sn capsules are used, the combustion temperature may be increased to 1,800° C. Therefore, it is possible to artificially increase the combustion temperature by using Sn capsules, which is impossible with AQF pretreatment apparatus alone.

(12) According to one embodiment of the present invention, inorganic samples are placed in Sn capsules and continuously transferred to a combustion position inside the AQF pretreatment apparatus together with WO.sub.3 to temporarily raise the maximum combustion temperature (internal temperature of the AQF pretreatment apparatus) of the inorganic samples to about 2,000° C. If the maximum combustion temperature is close to 2,000° C., the Sn capsules melt and release heat, which causes the samples in the capsules to be more quickly and more fully decomposed and release gaseous Cl.

(13) According to one embodiment, the samples are continuously transferred to a combustion position in the AQF pretreatment apparatus for less than 10 seconds, for example 3 to 8 seconds.

(14) According to one embodiment, the gaseous Cl released by the combustion is collected in an absorbing solution (e.g., a solution of 500 mL of H.sub.2O and 1.5 mL of H.sub.2O.sub.2).

(15) According to one embodiment, the Sn capsules may be Sn capsules commercially available from LECO Corporation, for example, 502-040 having a thickness of 0.05-0.1 mm or 240 06400 having a thickness of 0.01 mm or less.

(16) The present invention provides a method for quantitative analysis of residual Cl in zinc ferrite synthesized from chloride precursors such as zinc chloride, iron chloride, etc., wherein the samples contained in Sn capsules are continuously transferred into the AQF pretreatment apparatus together with WO.sub.3 and are subject to combustion. This makes it possible to use IC analysis by using AQF pretreatment apparatus, which was used for quantitative analyses of organic samples only, for quantitative analyses of residual Cl in synthesized inorganic materials.

(17) Hereinafter, embodiments of the present invention will be described in detail in order to facilitate those skilled in the art to which the present invention pertains. However, the present invention may be embodied with various modifications and variations and is not limited to the embodiments described herein.

Example

(18) In the examples and comparative examples, quantitative analyses of CI in solid zinc ferrite samples were performed by using IC device equipped with AQF pretreatment apparatus of Mitsubishi Chemical Analytech Co., Ltd., The length of the combustion tube of the AQF is about 320 mm in total, and the combustion of the above samples was performed at the 160 mm position of the combustion tube.

(19) Quantitative analysis experiments were repeated for each of the four zinc ferrite samples of different contents three times or more per each sample. The results of the analyses obtained are shown in Table 1 below.

(20) TABLE-US-00001 TABLE 1 Analyses of Cl content in zinc ferrite samples sample Cl content zinc ferrite 1 average 0.108% (water washing) relative standard 3.2 deviation (RSD) (%) zinc ferrite 2 average 0.171% RSD (%) 1.4 zinc ferrite 3 average 1.957% (water washing) RSD (%) 0.3 zinc ferrite 4 average 26.729% RSD (%) 0.9

(21) In addition, for four zinc ferrite samples with different contents, four different combustion conditions were set, and the quantitative analysis experiments were repeated three times or more per each sample under each condition. The results of the analyses obtained are shown in Table 2 below. The values in Table 2 represent the average values.

(22) TABLE-US-00002 TABLE 2 Analyses of Cl content in zinc ferrite samples under four different conditions sample Condition 1.sup.1) Condition 2.sup.2) Condition 3.sup.3) Condition 4.sup.4) zinc ferrite 1 0.108% 0.102% 0.099% 0.101% (water washing) zinc ferrite 2 0.171% 0.172% 0.169% 0.170% zinc ferrite 3 1.957% 1.908% 1.907% 1.936% (water washing) zinc ferrite 4 26.729% 26.216% 26.572% 26.419% .sup.1)Condition 1 - Using Sn capsules and WO.sub.3 .sup.2)Condition 2 - Using neither Sn capsules nor WO.sub.3 .sup.3)Condition 3 - Using WO.sub.3 only .sup.4)Condition 4 - Using Sn capsules only

(23) Lastly, by using a thin or thick Sn capsules, and by inserting the samples into the AQF step by step or continuously transferring the samples to the combustion position (160 mm) of the combustion tube of AQF by adjusting the sample transfer program, the quantitative analysis experiments according to the present invention were carried out (repeated three times or more per each sample). The results of analyses of the Cl content in each zinc ferrite sample are shown in Table 3 below. The values in Table 3 represent average values.

(24) TABLE-US-00003 TABLE 3 Analyses of Cl content in zinc ferrite samples according to thickness of Sn capsules and transfer program of samples zinc ferrite 1 TP1.sup.1) MTP1.sup.2) MTP2.sup.3) MTP3.sup.4) MTP4.sup.5) Condition 5.sup.a) 0.106% 0.095% 0.096% 0.093% 0.099% zinc ferrite 1 TP1 MTP1 MTP2 MTP3 MTP4 Condition 6.sup.b) 0.109% 0.110% 0.109% 0.111% 0.112% .sup.a)Condition 5 - Thermo Fisher scientific, Sn capsule (240 06400) (diameter 8.0 mm × height 5.0 mm) - thin (0.01 mm or less) .sup.b)Condition 6- LECO Corporation, Sn capsule (502-040) (diameter 6.0 mm × height 8.0 mm) - thick (0.05 to 0.1 mm) .sup.1)TP1 - Transferring the sample to the combustion position step by step according to the temperature program of the sample .sup.2)MTP1 - Transferring the sample continuously up to 160 mm of AQF at 20 mm per second .sup.3)MTP2 - Transferring the sample continuously up to 160 mm of AQF at 30 mm per second .sup.4)MTP3 - Transferring the sample continuously up to 160 mm of AQF at 40 mm per second .sup.5)MTP4 - Transferring the sample continuously up to 160 mm of AQF at 50 mm per second

(25) As can be seen in the results of Tables 1 to 3, the method of analyzing the Cl content in the zinc ferrite samples according to the method of the present invention showed a relative standard deviation value of 3% or less. The method according to the present invention uses both Sn capsules and WO.sub.3, and thus the recovery rate of Cl is higher than that in the case of not using Sn capsules and WO.sub.3 or using only one of them. In the case of using the thick Sn capsule and continuously transferring the samples to the heating position inside the AQF, the highest recovery rate of Cl was shown.

(26) Therefore, according to the present invention, it is possible to quantitatively analyze residual Cl content in synthesized inorganic materials by using IC device equipped with AQF pretreatment apparatus.

(27) While the present invention has been particularly shown and described with reference to specific embodiments thereof, it will be apparent to those skilled in the art that this specific description is merely a preferred embodiment and that the scope of the invention is not limited thereby. It is therefore intended that the scope of the invention be defined by the claims appended hereto and their equivalents.