Title of Invention

SOLUTION SPRAY PROCESS FOR PREPARATION OF INORGANIC NANOSIZED PARTICLES USING CO-PRECIPITATION TECHNIQUE IN MICELLAR MODE

Abstract

The basis of novel process for synthesis of nanoparticles is to control reaction at molecular level (bottom to top approach) for regulating the particle size. The idea is to contact reactants at highly atomized level through spray and use surfactants at concentration in excess of CMC to prevent the resultant nanoproduct from meeting each other to avoid aggregation. Accordingly, the present invention provides a solution spray process for the preparation of highly dispersed nanoparticles varying from 5 to 80 nm as described herein, said process comprising: 1. Dissolving the precursor and precipitator independently in solvent to form concentrated solutions at specified strength. 2. Mixing the appropriate surfactant either with precursor or precipitator. North Maharashtra University, Jalgaon 3. Spraying these solutions independently and simultaneously in co-precipitation reactor to form the reaction zone in flowing thin film form. 4. Controlling the individual spray to maintain fan pattern in flowing reaction film. 5. Controlling input flow rates and discharge rates for providing specific residence time/ holding time. 6. Filtering the resultant reaction mixture, containing nanosized product, through fine mesh filter. 7. Washing with solvent to remove soluble by-products (Salt) formed during the reaction. 8. Low temperature vacuum drying of nanoparticles to eliminate residual traces of solvent.

Full Text

FORM 2 THE PATENT ACT 1970 (39 OF 1970) & THE PATENTS RULES, 2003 COMPLETE SPECIFICATION TITLE OF THE INVENTION SOLUTION SPRAY PROCESS FOR PREPARATION OF INORGANIC NANOPARTICLES USING CO-PRECIPITATION TECHNIQUE IN MICELLAR MODE APPLICANT NORTH MAHARASHTRA UNIVERSITY, JALGAON SOLUTION SPRAY PROCESS FOR PREPARATION OF INORGANIC NANOPARTICLES USING CO-PRECIPITATION TECHNIQUE IN MICELLAR MODE The following specification particularly describes the invention and the manner in which it is to be performed FIELD OF THE INVENTION The present invention relates to a simple solution process performed in low viscosity medium for the rapid preparation and easy recovery of highly dispersed nanoparticles with controlled sizes in the range of 5 to 80 nanometers. BACKGROUND OF THE INVENTION Nanoparticles are a new class of colloidal materials available in nano size ( In the present invention, surfactant is added to the precursor for subsequent control of size during formation of nanosized particles. The concentration of the surfactant is required to be greater than the 'Critical Micelle Concentration' (CMC) so as to promote synthesis in micellar mode. The precipitator and precursor are sprayed in the form of fine droplets. These atomized droplets get reacted within micelles and hence the growth of the nano sized product is initiated at a number of sites in semi batch mode. In this way, coagulation of two or more crystals is inhibited and product is retained in nano form. OBJECTS OF THE INVENTION Most of the unique properties of nanoparticles require not only the particles to be of nanosize but also the particles to be dispersed without agglomeration. Inorganic nanoparticles have a common tendency of agglomeration and need a technique for control of size. How to synthesize uniform nanoparticles with narrow size distribution has been one of the key problems in the area of nanoscience and technology. Accordingly, the main object of the present invention is to develop a simple and rapid process for the preparation of highly dispersed nanoparticles having sizes smaller than 80 nm and with rigid control on particle size distribution. SUMMARY OF THE INVENTION The basis of solution spray process for synthesis of nanoparticles is to control reaction at molecular level (bottom to top approach) for regulating particle size. The idea is to spray reactants using fine nozzles and contact them at highly atomized level in film regime in presence of surfactant micelles to form the product nanoparticles rapidly and prevent the resultant product from meeting each other to avoid aggregation. Modern surfactant and colloid chemistry as well as chemical kinetics have thus been largely utilized to control size and morphology at the nanometer level. To meet the above objects and to overcome the problems existing in the prior art, the present invention provides a process for the preparation of highly dispersed nanoparticles varying from 5 to 80 nm as described herein, said process comprising: 1. Dissolving the precursor and precipitator independently in solvent to form concentrated solutions at specified strength. 2. Mixing the appropriate surfactant either with precursor or precipitator. 3. Spraying these solutions independently and simultaneously in co-precipitation reactor to form the reaction zone in flowing thin film form. 4. Controlling the individual spray to maintain fan pattern in flowing reaction film. 5. Controlling input flow rates and discharge rates for providing specific residence time/ holding time. 6. Filtering the resultant reaction mixture, containing nanosized product, through fine mesh filter. 7. Washing with solvent to remove soluble by-products (Salt) formed during the reaction. 8. Low temperature vacuum drying of nanoparticles to eliminate residual traces of solvent. DETAILED DESCRIPTION OF THE INVENTION Particularly, the present invention relates to a simple, micellar, non-viscous, fast and improved process for the preparation of highly dispersed nanoparticles sizes in the range of 10 to 50 nanometers, through reaction in atomized mode in micelles In one form of the invention, the process for the preparation of highly dispersed nanoparticles may involve methods for manufacturing nanoscale materials in high volume, low cost mode. In one more form of the present invention, the process for the preparation of highly dispersed nanoparticles may include design of reactors (contactors) for intimate contact of precursor and precipitator. In another form of the present invention, the process for the preparation of highly dispersed nanoparticles may include variables controlling atomization of precursor and precipitator. In another form of the present invention, the process for the preparation of highly dispersed nanoparticles through establishment of these variables governing the particle size at nano scale, In yet another form of the present invention, the process for the preparation of highly dispersed nanoparticles may include methods for synthesis of nano particles of metal salts such as carbonates and sulphates. In one more form of the present invention, the process for the preparation of highly dispersed nanoparticles may include methods for synthesis of metal hydroxides. In one more form of the present invention, the process for the preparation of highly dispersed nanoparticles may include parameters influencing particle size/ surface area and particle size distribution. In some embodiments, an objective of the present invention is to describe carbonates as extenders for promoting hiding power of paints. In some embodiments, an objective of the present invention is to describe sulfates as fillers for composites and automotive surfacers. In some embodiments, an objective of the present invention is to describe hydroxides as flame retardant, fillers for nanocomposites. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Fig. 1 relates to a design of Contactor/ Reactor particularly to a Reaction Vessel equipped with turbine impeller (06) with speed regulator (09) for uniform mixing, atomizer (14) for fine spray, energy regulator network for temperature control (05), pressure gauge (15), vent valve (16), entrainment separator (10), safety attachment-rupture disc (18) and sight glass (17) for visual observation of progress of reaction. The system was thus designed for intimate contacting of precursor and precipitator. Fig. 2 relates to TEM analysis of nano CaC03 showing the actual size of nano particles of CaC03 with the particle size varying between 10 - 40 nm, the maximum number of particles being of approximately 20 nm. Fig. 3 relates to XRD analysis of nano CaC03. Fig. 4 relates to the mechanism of stabilization of dispersed nanoparticles through entropic or electrical double layer interaction between Surfactant Micelles and Nanoparticles. DETAILED DESCRIPTION WITH RESPECT TO EXAMPLES AND DRAWING According to figure 1, the separately prepared solutions of precursor (PC) and precipitator (PP) are sprayed through the individual nozzles of atomizers by reciprocating compressor (01) at controlled pressure and flow rate. Formation of falling film reaction regime (3) of atomized reactants between impeller and atomizer is the key to success of co-precipitation reaction at molecular scale. A turbine agitator (06) rotating at a speed between 75-100 rpm takes up the rapidly falling film zones of atomized reaction mixture (3) and leads the reaction rapidly to form product nanoparticles with rigid control of size in presence of surfactant micelles. The dimensions of spray semi batch reactor are as given in Fig. 1. The temperature of reaction mixture was regulated through PID type of control (2) of electrical heating of coils (13) maintained in jacket (19) of reactor through set point comparison (08) with that indicated by thermowel (12). The baffles (4) are maintained in the path of exhaust at the top of reactor to recover the entrained Nanoparticles from outgoing air. The exhaust is then led through entrainment separator for recovery of residual Nanoparticles. A butterfly valve (7) located at dish bottom of the reactor discharges the reaction mixture for filtration of product from reaction mixture. Siphoning arrangement (11) is provided to maintain the level of reaction mixture in the reactor and also for decanting the excess solvent. The process is monitored through control of orifice size, reciprocating compressor pressure, discharge flow rate, speed, reaction temperature, distance between atomizer and reaction zone, spreader pattern etc. EXAMPLE 1 2 M solution of ammonium bicarbonate (NH4HC03) and 3.5 M solution of calcium chloride (CaCI2) containing 0.2% Sodium Dodecyl Sulphate were prepared separately and sprayed in stoichiometric proportions at the rate of 0.01 ml/sec and 0.35ml/ Sec, respectively by using atomizers in the form of fine droplets into the reactor containing sufficient water covering impeller blades. The reaction mixture was stirred by means of agitator at 75-100 rpm so as to prevent agglomeration of particles and to renew reaction surfaces. After providing residence time of 20 min, the product was separated through fine porosity filter followed by repeated deionised water washing to remove ammonium chloride formed as by product. The product was air dried to obtain particles in powdery form. Reaction: CaCI2 +2NH4HCO3 ® CaCO3 (Nanoparticles) ¯ + 2NH4CI +CO2­+ H2O precursor precipitator Water insoluble Water soluble The yield of CaCO3 nanoparticles was 87%. The synthesized particles (in powdery form) were characterized by TEM (Transmission Electron Microscopy), and X-ray Diffraction Technique. The TEM indicated the particle size varying from 1 to 80 nm. Nano CaCO3 finds wide use as spacing extender in Paint formulations as part replacement for hiding TiO2 pigment. EXAMPLE 2 4 M solution of ammonium sulphate ((NH4)2SO4 ) and 2 M solution of Barium Chloride (BaCI2) containing 0.4% Sodium Dodecyl Sulphate were prepared separately and sprayed in stoichiometric proportions at the rate of 0.023ml/sec and 0.01ml/ Sec, respectively, by using atomizer in the form of fine droplets into the reactor containing sufficient water covering impeller blades. The reaction mixture was stirred by means of agitator at 75-100 rpm so as to prevent agglomeration of particles and to renew reaction surfaces. After providing residence time of 30 min, the product was separated through fine porosity filter followed by repeated deionised water washing to remove ammonium chloride formed as by product. The product was air dried to obtain particles in powdery form. Reaction: ((NH4)2SO4 + BaCI2. 2H2O ® BaSO4 (Nanoparticles) ¯ + 2NH4CI + 2H2O precipitator Precursor Water insoluble Water soluble The yield of BaSO4 nanopaticles was 79%. The synthesized particles (in powdery form) were characterized by TEM (Transmission Electron Microscopy), and X-ray Diffraction Technique. The TEM indicated the particle size varying from 5 to 90 nm. Nano BaSO4 finds wide use as extender to promote rub resistance of Automotive Surfacer of composite automotive paints. EXAMPLE 3 25 % v/v solution of ammonium hydroxide (NH4OH) and 2.5 M solution of Magnesium chloride (MgCI2) containing 0.2% Sodium Dodecyl Sulphate were prepared separately and sprayed in stoichiometric proportions at the rate of 0.0425ml/sec and 0.01ml/ Sec respectively, by using atomizer in the form of fine droplets into the reactor containing sufficient water covering impeller blades. The reaction mixture was stirred by means of agitator at 75-100 rpm so as to prevent agglomeration of particles and to renew reaction surfaces. After providing residence time of 20 min, the product was separated through fine porosity filter followed by repeated deionised water washing to remove ammonium chloride formed as by product. The product was air dried to obtain particles in powdery form. Reaction: MgCl2 + 2 NH4OH ® Mg (OH)2 (Nanoparticles) ¯ + 2NH4CI precursor precipitator Water insoluble Water soluble The yield of Mg (OH)2 nanoparticles was 86%. The synthesized particles (in powdery form) were characterized by TEM (Transmission Electron Microscopy), and X-ray Diffraction Technique. The TEM indicated the particle size varying from 1 to 80 nm. Nano Mg (OH)2 finds wide use as filler to promote fire retardance of polymer composites. The different variables governing degree of atomization and intimacy of reactant contact were established for all the three examples. The illustrations of effects of these variables have been provided for synthesis of calcium carbonate (CaC03) nanopartcles in example 4 to 8. EXAMPLE 4 The viscosity of the reaction phase was varied between 12 to 20 cp by addition of PEG (Mw. 6000) to reaction bath. Higher the viscosity of reaction phase, lower was the chances of aggregation. However use of protective colloids necessitated increase in washing frequencies resulting in drop in yield form 25-50 % of the regular yield. The viscosity of the precipitator/ precursor solution was varied between 10 to 12 cp based on the concentration of reactants. Lower the viscosity of stream passing through the atomizer orifice, better was the degree of atomization. Lower viscosity of atomized droplets provided better reaction contact. EXAMPLE 5 The nozzle orifice diameter was varied from 0.02 to 0.09 cm. Smaller the orifice better was the degree of atomization. However, smaller orifice must have good spreading pattern for permitting larger distribution of atomized droplets over reaction surface. The spreader pattern was used to adjust the shape of the stream of atomized droplets coming from the atomizer. An elliptical cross sectional pattern permitted more efficient application. EXAMPLE 6 The CMC's of different surfactants vary over a wider range from about 10"7 to 10"3 gm/lit. Presence of surfactant in reaction phase at concentrations exceeding its CMC permits reaction in micelle mode and thus controls stabilization of nanoparticles size through entropic and/or electrical double layered stabilization. Addition of surfactant in reactant stream passing through orifice at CMC level reduces surface tension to a lower magnitude and lower the surface tension, better will be the atomization. EXAMPLE 7 The distance between reaction zone and atomizer orifice was varied by changing the angle of spray with the horizontal plane from 0° (shortest) to 90° (longest). Larger the distance, better was the distribution of atomized droplets over reaction zone permitting correct fan pattern and minimum bounce back loss. At the same time, with increase in distance some atomized droplets missed the reaction surface, thus causing increase in overspray and fallout losses. EXAMPLE 8 Increase in reaction temperature from 30 to 50 °C increased reaction speed, thus enhancing formation rate of nanoparticles. But at the same time increase in temperature of reaction phase reduced its viscosity, increased kinetic energy of nanoparticles causing more no. of interparticle collisions leading to aggregation. Increasing temperature of reaction stream passing through orifice (hot spray) reduces viscosity, permits better atomization and allows handling of concentrated solutions, hence permitting more production rates. The reproducibility of the method is governed by precision of control with manual spray application. DEFINITIONS "Precursor," as the term is used herein, encompasses any raw substance that can be transformed into a powder of same or different composition. In certain embodiments, the precursor is a liquid. The term precursor includes, but is not limited to, organometallics, organics, inorganics, solutions, dispersions, melts, sols, gels, emulsions, or mixtures. "Precipitators", as the term is used herein, encompasses any raw substance that can be used to transform precursor derivative into a powder of same or different composition. In certain embodiments, the precursor is a liquid. The term precursor includes, but is not limited to, strong or weakly basic, organic as well as inorganic materials. "Powder," as the term is used herein, encompasses oxides, carbides, nitrides, chalcogenides, metals, alloys, and combinations thereof. The term includes hollow, dense, porous, semi-porous, coated, uncoated, layered, laminated, simple, complex, dendrite, inorganic, organic, elemental, non-elemental, dispersed, composite, doped, undoped, spherical, non-spherical, surface functionalized, surface non-functionalized, stoichiometric, and non-stoichiometric forms or substances. The pattern of flattened cone obtained after atomization through spreader control is described by the term Fan. The terms "nanopowders," "nanosize powders," "nanoparticles," and "nanoscale powders" are used interchangeably and refer to powders that simultaneously satisfy particles having a mean size less than 100 nanometers. For example, in some embodiments, the nanopowders are powders that have particles with a mean domain size less than 100 nanometers and with an aspect ratio ranging from 1 to 1,000,000. Micelles are submicroscopic aggregates typically containing 30 to 100 surfactant molecules, with the hydrophobic parts of each molecule oriented toward the centre and the hydrophobic parts oriented outward in contact with water. (Above CMC-Critical Micelle concentration, non polar ends of surfactant molecule associated with other in clusters called micelles.) We claim, 1. A process for the preparation of highly dispersed nanoparticles varying in size between 1 nm to 80 nm, said process comprising a. Dissolving the reactants independently in solvent to form concentrated solutions b. Mixing one of the solutions with soluble surfactant. c. Spraying these solutions through atomisers in semibatch reactor to form falling thin film reaction regime. d. Controlling the individual spray to maintain fan pattern in flowing reaction film. e. Controlling input flow rates and discharge rates for providing specific residence time/ holding time. f. Filtering the resultant reaction mixture, containing nanosized product, through fine mesh filter. g. Washing with solvent to remove soluble by-products (Salt) formed during the reaction. h. Low temperature vacuum drying of nanoparticles to eliminate residual traces of solvent. 2. A process as in claim 1, wherein, the reactant comprises of chlorides of alkaline earth metals 3. A process as in claim 1, wherein, the reactant comprises of sulphates of transition metals 4. A process as in claim 1, wherein, the solvent comprises of water in micelle systems 5. A process as in claim 1, wherein, the surfactant comprise of Dodecyl benzene sulfonate, sodium lauryl sulfate, alpha olefin sulphonate etc. 6. An atomizer with spreader pattern for spraying finer droplets in fan pattern and subsequent formation of falling film of reaction system. North Maharashtra University, Jalgaon 7. A semi batch system for intimate contacting of precursor and precipitator and preparation of highly dispersed nanoparticles comprising a Contactor equipped with turbine, impeller, energy regulator, pressure gauge, vent valve, safety attachment and sight glass. 8. A solution spray process for the preparation of highly dispersed nanoparticles substantially as described herein and illustrated with the help of examples and drawings. Abstract The basis of novel process for synthesis of nanoparticles is to control reaction at molecular level (bottom to top approach) for regulating the particle size. The idea is to contact reactants at highly atomized level through spray and use surfactants at concentration in excess of CMC to prevent the resultant nanoproduct from meeting each other to avoid aggregation. Accordingly, the present invention provides a solution spray process for the preparation of highly dispersed nanoparticles varying from 5 to 80 nm as described herein, said process comprising: 1. Dissolving the precursor and precipitator independently in solvent to form concentrated solutions at specified strength. 2. Mixing the appropriate surfactant either with precursor or precipitator. North Maharashtra University, Jalgaon 3. Spraying these solutions independently and simultaneously in co-precipitation reactor to form the reaction zone in flowing thin film form. 4. Controlling the individual spray to maintain fan pattern in flowing reaction film. 5. Controlling input flow rates and discharge rates for providing specific residence time/ holding time. 6. Filtering the resultant reaction mixture, containing nanosized product, through fine mesh filter. 7. Washing with solvent to remove soluble by-products (Salt) formed during the reaction. 8. Low temperature vacuum drying of nanoparticles to eliminate residual traces of solvent.

Documents:

1639-MUM-2007-ABSTRACT(16-2-2009).pdf

1639-MUM-2007-ABSTRACT(27-8-2007).pdf

1639-mum-2007-abstract(granted)-(26-6-2009).pdf

1639-mum-2007-abstract.doc

1639-mum-2007-abstract.pdf

1639-MUM-2007-CANCELLED PAGES(16-2-2009).pdf

1639-MUM-2007-CLAIMS(16-2-2009).pdf

1639-MUM-2007-CLAIMS(COMPLETE)-(27-8-2007).pdf

1639-mum-2007-claims(granted)-(26-6-2009).pdf

1639-mum-2007-claims.doc

1639-mum-2007-claims.pdf

1639-MUM-2007-CORRESPONDENCE(10-1-2012).pdf

1639-MUM-2007-CORRESPONDENCE(10-9-2007).pdf

1639-MUM-2007-CORRESPONDENCE(16-2-2009).pdf

1639-MUM-2007-CORRESPONDENCE(IPO)-(17-7-2009).pdf

1639-MUM-2007-CORRESPONDENCE(IPO)-(29-8-2008).pdf

1639-mum-2007-correspondence-received.pdf

1639-mum-2007-description (complete).pdf

1639-MUM-2007-DESCRIPTION(COMPLETE)-(16-2-2009).pdf

1639-MUM-2007-DESCRIPTION(COMPLETE)-(27-8-2007).pdf

1639-mum-2007-description(granted)-(26-6-2009).pdf

1639-MUM-2007-DRAWING(16-2-2009).pdf

1639-MUM-2007-DRAWING(27-8-2007).pdf

1639-mum-2007-drawing(granted)-(26-6-2009).pdf

1639-mum-2007-drawings.pdf

1639-MUM-2007-FIRST EXAMINATION REPORT(16-2-2009).pdf

1639-MUM-2007-FORM 1(27-8-2007).pdf

1639-MUM-2007-FORM 15(10-1-2012).pdf

1639-MUM-2007-FORM 18(11-9-2007).pdf

1639-mum-2007-form 2(16-2-2009).pdf

1639-MUM-2007-FORM 2(COMPLETE)-(27-8-2007).pdf

1639-mum-2007-form 2(granted)-(26-6-2009).pdf

1639-MUM-2007-FORM 2(TITLE PAGE)-(16-2-2009).pdf

1639-MUM-2007-FORM 2(TITLE PAGE)-(COMPLETE)-(27-8-2007).pdf

1639-mum-2007-form 2(title page)-(granted)-(26-6-2009).pdf

1639-MUM-2007-FORM 9(11-9-2007).pdf

1639-mum-2007-form-1.pdf

1639-mum-2007-form-2.doc

1639-mum-2007-form-2.pdf

1639-mum-2007-form-3.pdf

1639-mum-2007-form-8.pdf

1639-MUM-2007-SPECIFICATION(AMENDED)-(16-2-2009).pdf

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