Title of Invention

"A PROCESS FOR THE PREPARATION OF NANO-SIZE MANGANESE COMPOUND"

Abstract

The present invention relates to a process for the preparation of nano-size manganese compound. More particularly the present invention relates to a process for the preparation of nano size rod of MnOOH and nano size particles of Mn304 suitable for use in batteries, catalysis, & electrochromic magnetic materials. The novel process of present invention of making nano-size rods of MnOOH (10 -70 nm diameter and 0.10 to 5 urn length) and Mn304 particles (20 - 100 nm) is carried out at ambient temperature and pressure and does not require the use of expensive organic molecules such as ethanol, amines or organic acids.

Full Text

The present invention relates to a process for the preparation of nano-size manganese compound. More particularly the present invention relates to a process for the preparation of nano size rod of MnOOH and nano size particles of Mn3O4 suitable for use in batteries, catalysis, electrochromic, magnetic materials (Weing Zhang, Zeheng Yang, Yi Liu, Shupei Tang, Xiaozhao Han, Min Chen. Journal of Crystal Growth Vol. 263, Issue 1-4 (1) March (2004) 394-399 and as a precursor material of (i) manganese vanadium oxide (WenLiang He, YongCai Zhang, XiaoXue Zhang, Hao Wang, Hui Yan, Journal of Crystal Growth 252 (2003) 285-288), (ii) Li-Mn Spinel (WenLiang He, YongCai Zhang, XiaoXue Zhang, Hao Wang, Hui Yan, Journal of Crystal Growth 252 (2003) 285-288) and (iii) as a powerful oxidant for the treatment of organic wastes (D.K. Cha and S.M. Park, Department of Chemistry, University of New Mexico, Albuquerque NM, 87131) and (iv) oxidation of Cr (III) to Cr (VI) (C. Annette Johnson and Aglaia, Geochimica et Cosmochimica Acta, Vol. 55, Issue 10, October 1991, Pages 2861-2866) References may be made to following practices reported in literature for making nano-sized Mn3O4, MnOOH and related materials: The processes reported for making nano sized Mn3O4 and MnOOH species involve (i) solvo-thermal processes wherein a compound of manganese such as potassium permanganate/ manganese sulphate is reacted with ethanol/aqueous ethanol solution for 8-24 hours between 100-160°C in an autoclave, (ii) reaction of manganese sulphate with aqueous solution of ethylamine in the presence of a surface active agent followed by aging at 120°C for 3 days in an autoclave, (iii) Sol-gel processing in which potassium permanganate is reacted with fumaric acid under controlled conditions to obtain a sol, which, when coated on alumina template and heated at 500 °C for 24 hours, yielded nano-fibres. Nano sized Mn203 has been prepared by reduction of Mn02 with ethanol in an autoclave maintained at 130°C for 24 hours or of potassium permanganate with aqueous hydrazine under ambient conditions. A US patent (Patent Application No. 20040005483) has been granted to the process of making films of substituted manganites having about 100 nm grain size and powders 16-330 nm crystallites. The mixed solutions of lanthanum, strontium and manganese acetates were dried in air at 110°C to form gel. The gel was pyrolysed at 450-550°C to complete decomposition and to drive the organics. The resultant powder was fired at 900 - 1200°C for 100 minutes to get above nano materials. The drawbacks in the procedures of making nano-size Mn3O4 and MnOOH by above-mentioned processes are as follows: I. Most of the processes for making nano-size Mn3O4 and MnOOH described above necessitate the use of an autoclave. II. Another drawback is that the above processes require to be carried out at elevated temperatures. III. Significant quantity of organic species such as solvent, amines or organic acid are needed to carryout reduction of manganese bearing compounds. The main object of the present invention is to provide a process for the preparation of nano-size manganese compounds which obviates the drawbacks of the existing processes as described above. Another object of the present invention is to provide a process for the preparation of nano size MnOOH and Mn3O4, Yet another object of the present invention is to obviate the need of using alcohols/amines/organic acids etc., which are comparatively expensive, for making nano-size MnOOH and Mn3O4. Yet another object of the present invention is to develop a process for making nano-size MnOOH and Mn3O4, under ambient conditions and thus obviating the need of maintaining elevated temperatures for elongated periods. Yet another object of the present invention is to provide a process for making nano-size MnOOH and Mn3O4, under ambient pressures and thus obviating the need of an autoclave. Yet another object of the present invention is to provide a process for making nano-size MnOOH and Mn3O4, utilizing an inexpensive manganese compound such as manganese sulphate, manganese chloride etc and ammonium hydroxide as raw materials in the presence of minor quantity of a surface active compound such as sodium lauryl sulphate or cetyl trimethyl ammonium bromide. Accordingly, the present invention provides a process for the preparation of nano size manganese compound which comprises; i)) preparing aqueous solution of manganese salt and a surface active agent, ii) adding slowly an aqueous solution of ammonia to an aqueous solution of step i) at a rate of 0.1 to 0.5 ml/minute, under continuous stirring to obtain a suspension, iii) ageing the said suspension for a period of 20-24 hours, followed by filtration and washing with water, iv) drying suspension of step iii) at an ambient temperature in dry air to obtain the precipitate of the aggregation of nano size rods and nano size particles of manganese compounds, v) sonicating the above said precipitate in acetone followed by filtration and drying at an ambient temperatures to obtain the desired nano size manganese compound such as nano size rod of MnOOH and nano size particles of Mn304. In an embodiment of the present invention the manganese salt used is selected from manganese sulphate and manganese chloride. In yet another embodiment the surface active agent used is selected from sodium lauryl sulphate and cetyl tri methyl ammonium bromide. In yet another embodiment the concentration of manganese salt used in aqueous solution is in the range of 0.1 to 1% (w/v). In yet another embodiment the concentration of ammonium hydroxide used is in the range of 1 to 4 %. (w/v). In yet another embodiment the concentration of surface active agent used is ranging between 2.66 x 10-3 to 3.3 x 10-2 % (w/v). In yet another embodiment the nano size rods of manganese compound obtained is nano size rod of MnOOH. In yet another embodiment the nano size rods of MnOOH obtained is in the range of 10 - 70 nm in diameter and 0.1- 5.0 urn in length. In yet another embodiment the nano size particles of manganese compound obtained is nano size particles of Mn3O4. In still another embodiment the particle size of nano size particles of Mn3O4 obtained is in the range of 20-100nm. The complete description of all the process steps using various ingredients in the present invention of a novel process of making nano-size MnOOH and Mn3O4, involves preparation of a 0.1 to 1 % (w/v) aqueous solution of a manganese compound such as manganese sulphate in the presence of 0.01 to 0.1% surface active agent such as sodium lauryl sulphate, cetyl tri methyl ammonium bromide etc. and another solution containing 1- 4% aqueous ammonia. The aqueous ammonia solution is added very slowly (0.2 ml/minute) to the aqueous solution of manganese compound and surface active agent to precipitate nano-size MnOOH and Mn3O4 under continuous stirring using a magnetic stirrer. The precipitate is filtered, washed with distilled water and dried at ambient temperature in dry air. For converting nano size rods of MnOOH to nano size Mn3O4, 0.1 to 1.0 gm precipitate is ultrasonicated in 50 to 100 ml acetone for 10 to 30 minutes, filtered and dried at ambient temperatures. The novelty of the present invention with respect to prior art of making nano size manganese compound lies in the fact that (i) the process of the present invention obviates the need of use of expensive organic molecules such as ethanol, amines and organic acids and is carried out at an ambient temperature and pressure without the use of an autoclave. Description of drawings : Figure 1: X ray diffraction pattern of nano size samples showing the presence of nano-size MnOOH and Mn3O4. Figure. 2a&b: Scanning Electron Micrographs of sample showing (a) nano-size particle of Mn3O4 (b) Nano-rods of MnOOH. Fig. 3&b: Scanning Electron Micrographs of sample showing (a) & (b) nano-size particle of Mn3O4 particles and Nano-rods of MnOOH. Figure. 4. Transmission Electron Microscopy of sample dispersed in acetone showing Mn3O4 particles. Figure 5. X-ray diffraction of the sample dispersed in acetone showing square shaped and horizontal shaped Mn3O4 particles. Figure. 6. Transmission Electron Microscopy of sample dispersed in ethanol showing Mn3O4 particles and MnOOH rods. Figure 7a. Transmission Electron Microscopy of sample dispersed in ethanol showing agglomerated Nano-rods of MnOOH. Figure. 7b & c. Transmission Electron Microscopy of sample dispersed in ethanol showing agglomerated nano-particles of Mn3O4 respectively. Figure. 8. Transmission Electron Microscopy of sample prepared by using Manganese Chloride dispersed in water showing Nano-rods of MnOOH and Mn3O4 nano-particles. Figure 9 a & b: Transmission Electron Microscopy of sample (prepared by using Manganese Chloride and CTAB) dispersed in water showing nano-particles of Mn3O4 and nano-rods of MnOOH at different magnifications. The following examples are given by way of illustration and therefore should not be construed to limit the scope of the present invention. Example- 1. To prepare the nano-size MnOOH and Mn3O4 using the process of present invention, a solution of manganese sulphate mono-hydrate was prepared by dissolving accurately weighed 5.0 gm of A.R. grade manganese sulphate and 0.05 g sodium lauryl sulphate in 1500 ml double distilled water. To this solution, 280 ml of 4% aqueous ammonia solution was added at a rate of 0.2 ml/min. under continuous stirring with magnetic stirrer. The suspension so formed was aged for 24 hours, filtered using Whatman filter paper (No. 41) and washed thoroughly with distilled water to remove excess ammonia. The precipitate was dried in air and characterized for identifying the phases present and the shape/size of crystals. The X-ray diffractogram (cf. Fig. 1.) shows the presence of MnOOH and Mn3O4 phases. The Scanning Electron Micrographs of the material (cf. Fig. 2) show the presence of rod shaped crystals having a diameter between 50-70 nm and 2-5 urn length. The precipitate also contains nano-size crystals corresponding to Mn3O4 phase ( Xun Wang, Yadong Li, Materials Chemistry and Physics 82 (2003) 419-422) of 30-50 nm particle size and rod shaped crystals corresponding to MnOOH phase as described in literature ( Pramod K. Sharma, M.S. Whittingham, Material Letters 48 (2001) 319-323. Example - 2. In another variation of the parameters, to a solution containing 4 gms manganese sulphate and 0.05 gm sodium lauryl sulphate (total volume 1500 ml), 275 ml of 4% aqueous ammonia was added at a rate of 0.2 ml per minute. The suspension so formed was aged for 20 hours. After filtration and washing, the precipitate was examined under SEM to observe the presence of rod shaped MnOOH (40-70 nm diameter and 1-3 urn length) and particles of Mn3O4 (50 - 70 nm) (cf. Fig. 3). The precipitate (0.1 gm) was sonicated for 15 minutes in 100 ml acetone and then examined using Transmission Electron Microscope (TEM). Due to dehydration and sonication, the metastable MnOOH dissociates to form Mn3O4. These crystals are observed to be of 30-50 nm size (cf. Fig. 4). The X-ray diffractogram of dehydrated (sonicated in acetone) sample shows the presence of only Mn3O4 and the MnOOH phase is observed to be practically absent (cf. Fig. 5). Example 3. In another variation of the parameters, to a solution containing 4 gms manganese sulphate and 0.04 gm sodium lauryl sulphate (total volume 1500 ml), 275 ml of 4% aqueous ammonia was added at a rate of 0.2 ml per minute under continuous stirring with magnetic stirrer. The suspension so formed was aged for 24 hours and filtered using Whatman filter paper (No. 41) and washed thoroughly with distilled water to remove excess ammonia. The precipitate was dried in air. 25 mg of the precipitate was sonicated in 50 ml ethanol for 15 minutes. The examination of the sample under TEM showed the presence of Mn3O4 crystals of 20-50 nm size and nano-rods of MnOOH having a diameter of 20-50 nm and 200-500 nm length (cf. Fig. 6). It is further observed that nano-size crystals and rods try to agglomerate separately among themselves (cf. Fig. 7 a, b and c). Example 4. In another variation of the parameters, to a solution containing 5 gms manganese chloride (MnCI2 . 4 H2O) and 0.5 gm sodium lauryl sulphate (total volume 1500 ml), 180 ml of 4% aqueous ammonia was added at a rate of 0.2 ml per minute under continuous stirring with a magnetic stirrer. The suspension so obtained was aged for 24 hours. Due to finer particle size of the phases formed, during filtration, the material was filtered using Whatman filter paper (No. 42). The colloidal solution so obtained was sonicated for 15 minute and observed with Transmission Electron Microscope (TEM). The micrograph shows the presence of 10-20 nm diameter and 150-200 nm length nano-rods of MnOOH and crystals of Mn3O4 in the particle size range 30-100 nm (cf. Fig.8). Example No. 5: In yet another variation of parameters, 5 gms manganese chloride and 0.05 gm cetyl tri methyl ammonium bromide (CTAB) were dissolved in 1500 ml distilled water and 800 ml of 1% aqueous ammonia was slowly added at a rate of 0.5 ml per minute. The suspension so obtained was allowed to stand overnight and filtered. 0.1 gm of precipitate so obtained was sonicated for 15 minutes in 50 ml water, and examined under Transmission Electron Microscope (TEM). The micrographs show the presence of nano size crystals in the particle size range 50-80 nm and nano-rods of 40-60 nm diameter and 100-300 nm length (cf. Figure 9 (a)). A single rod and particle is shown in Figure 9 (b) at a higher magnification. The main advantages of the present invention are: I. The novel process of present invention of making nano-size rods of MnOOH (10 -70 nm diameter and 0.10 to 5 urn length) and Mn3O4 particles (20 - 100 nm) is carried out at ambient temperature and pressure. II. The novel process of making nano-size MnOOH and Mn3O4 does not require the use of expensive organic molecules such as ethanol, amines or organic acids. III. The novel process of making nano-size MnOOH and Mn3O4 does not require the use of an auto clave. IV. The novel process of present invention is useful for making nano-size MnOOH rods and particles of Mn3O4 . V. The novel process of present invention helps in making nano-size MnOOH and Mn3O4 using inexpensive reagents. We claim: 1. A process for the preparation of nano size manganese compound which comprises; i) preparing aqueous solution of manganese salt and a surface active agent, ii) adding slowly an aqueous solution of ammonia to an aqueous solution of step i) at a rate of 0.1 to 0.5 ml/minute, under continuous stirring to obtain a suspension, iii) ageing the said suspension for a period of 20-24 hours, followed by filtration and washing with water, iv) drying suspension of step iii) at an ambient temperature in dry air to obtain the precipitate of the aggregation of nano size rods and nano size particles of manganese compounds, v) sonicating the above said precipitate in acetone followed by filtration and drying at an ambient temperatures to obtain the desired nano size manganese compound such as nano size rod of MnOOH and nano size particles of Mn304. 2. A process as claimed in claim 1, wherein the manganese salt is selected from manganese sulphate and manganese chloride. 3. A process as claimed in claims 1&2, wherein the surface active agent is selected from sodium lauryl sulphate and cetyl tri methyl ammonium bromide. 4. A process as clamed in claims 1 to 3, wherein the concentration of manganese salt in aqueous solution is in the range of 0.1 to 1% (w/v). 5. A process as clamed in claims 1 to 4, wherein the concentration of aqueous ammonia is in the range of 1 to 4 %. (w/v). 6. A process as claimed in claims 1 to 5, wherein the concentration of surface active agent is ranging between 2.66 x 10-3 to 3.3 x 10-2 % (w/v). 7. A process as claimed in claims 1-6, wherein the nano size rods of MnOOH is in the range of 10 - 70 nm in diameter and 0.1- 5.0 urn in length. 8. A process as claimed in claims 1-7, wherein the particle size of nano size Mn304 is in the range of 20-100nm.

Documents:

1370-DEL-2005-Absract-(19-03-2012).pdf

1370-del-2005-abstract.pdf

1370-DEL-2005-Claims-(19-03-2012).pdf

1370-del-2005-claims.pdf

1370-DEL-2005-Correspondence Others-(19-03-2012).pdf

1370-del-2005-correspondence-others.pdf

1370-DEL-2005-Description (Complete)-(19-03-2012).pdf

1370-del-2005-description (complete).pdf

1370-del-2005-drawings.pdf

1370-del-2005-form-1.pdf

1370-del-2005-form-18.pdf

1370-del-2005-form-2.pdf

1370-DEL-2005-Form-3-(19-03-2012).pdf

1370-del-2005-form-3.pdf

1370-del-2005-form-5.pdf