Claims:1. A process for preparation of nano-fertilizer composition comprises step of:
a) an aqueous solution of plant nutrient is prepared by dissolving plant nutrient in water;
b) an aqueous solution of synthetic polymer is prepared by dissolving polymer in water;
c) adding drop-wise the aqueous solution of the synthetic polymer to step (a) solution;
d) keeping the step (c) solution at 50-500 rpm for 15-20 minutes for uniform mixing at room temperature and atmospheric pressure; and
e) adding drop-wise the uniformly mixed solution of step (d) to an aqueous solution of cross-linking agent and uniformly mixing it for 25-30 minutes to obtain colloidal dispersion of nano-fertilizer.
2. The process as claimed in claim 1, wherein the synthetic polymer is polyethyleneimine (PEI) having molecular weight in the range of 5000 Da to 25000 Da.
3. The process as claimed in claim 1, wherein ratio of percent plant nutrient: percent synthetic polymer (PEI) by weight is in the range from 1 to 2750 and the synthetic polymer concentration is varied from 0.02% to 1% wt./v.
4. The process as claimed in claim 1, wherein cross-linking agent is selected from the group comprising of carboxylic acid polymer or a conventional molecule such as sodium triphosphate (STPP).
5. The process as claimed in claim 1, wherein the carboxylic acid polymer is polyacrylic acid or a copolymer of acrylic and maleic acid.
6. The process as claimed in claim 5, wherein the carboxylic acid polymer cross linker is in the molecular weight range of 5000 Da to 70000 Da.
7. The process as claimed in claim 1, wherein the nano-fertilizer can optionally be formed in PEI system without the presence of a cross-linking agent.
8. A nano-fertilizer composition comprising plant nutrient entrapped in synthetic polymer nanoparticle formed by cross-linking of polymers polyethyleneimine and carboxylic acid polymer, wherein the nano-fertilizer composition is an aqueous solution.
9. The nano-fertilizer composition as claimed in claim 8, wherein the fertilizer is present in an amount 1% to 55% of the total weight of the nano-fertilizer composition.
10. The nano-fertilizer composition as claimed in claim 8, wherein the size of the nanoparticle is in the range of 1-1000 nanometers.
11. The nano-fertilizer composition as claimed in claim 8, wherein the plant nutrient is urea.
, Description:FIELD OF THE INVENTION
[0001] The present invention relates to a process for preparation of nano-fertilizer composition for improving the bioavailability of plant nutrients.

BACKGROUND OF THE INVENTION
[0002] Plants require certain essential nutrients for normal functioning and growth. Nutrient levels outside the amount required for normal functioning and growth may cause overall crop growth and health to decline due to either a deficiency or a toxicity. Nutrient deficiency occurs when an essential nutrient is not available in sufficient quantity to meet the requirements of a growing plant. Toxicity occurs when a nutrient is in excess of plant needs and decreases plant growth or quality.
[0003] Commercial fertilizers contain macronutrients and micro nutrients that are essential for plant growth and macronutrients are used by plants in relatively large amounts. As defined herein primary macronutrients are nitrogen (N), phosphorous (P) and potassium (K) while calcium (Ca), magnesium (Mg) and sulfur (S) are secondary macronutrients. All six nutrients are important for plant growth.
[0004] As defined herein, micronutrients required in small amounts for plant growth are boron (B), chlorine (Cl), manganese (Mn), iron (Fe), zinc (Zn), copper (Cu), molybdenum (Mo) and selenium (Se).
[0005] Nitrogen, phosphorus and potassium (NPK), which are required in large amounts for plants, are not always adequately available in natural soils to support the sustained growth of plants. Therefore, these macronutrients (NPK) are often needed to be applied externally through fertilizer.
[0006] Fertilizers, particularly synthetic fertilizers have a major potential to pollute soil, water and air; in recent years, many efforts were done to minimize these problems by agricultural practices and the design of the new improved fertilizers. Water soluble conventional fertilizers typically result in a large amount of macronutrients being lost by leaching and evaporation. Conventional fertilizers are generally applied on the crops by either spraying or broadcasting. However, one of the major factors that decide the mode of application is the final concentration of the fertilizers reaching to the plant. In practical scenario, very less concentration (much below to minimum desired concentration) reaches to the targeted site due to leaching of chemicals, fixation, drift, runoff, evaporation, hydrolysis by soil moisture, and photolytic and microbial degradation. It has been estimated that around 40-70% of nitrogen, 80-90% of phosphorus, and 50-90% of potassium content of applied fertilizers are lost in the environment and could not reach the plant, which causes sustainable and economic losses.
[0007] Hence, there remains a need for improvement in fertilizer to provide essential plant nutrients for agricultural application without causing or limiting environmental hazard.
[0008] Nanotechnology is an enabling technology. Metallic, oxide and semiconductor nanoparticles have properties entirely different from their bulk. Due to their unusual optoelectronic and physico-chemical properties, they find application in electronics, sensing, catalysis, paints, solar cells, etc. There are numerous manuscripts in the public domain that demonstrate this fact. Polymer nanoparticles are a different class of nanoparticles, which have the ability to entrap different entities. The objective of using polymer nanoparticles is to exploit the small size and its ability to penetrate tissue; and has been extensively used in pharma to design anti-cancer nano-drugs. The present invention is using this ability of polymer nanoparticles to entrap molecules as delivery vehicles inside plants.

OBJECT OF THE INVENTION
[0009] The primary object of the present invention herein is to provide a process of preparing the nano-fertilizer composition which is capable of slow release/controlled release of a plant nutrient inside plant system.
[0010] Yet another object of the present invention herein is to provide a nano-fertilizer composition using a synthetic polymer Polyethylenimine (PEI).
[0011] Yet another objective of the present invention is to provide a nano-fertilizer composition encapsulating nitrogen, phosphorous and potassium or NPK fertilizer compounds, secondary nutrients; and micronutrients to provide an economical and readily available source imminently suitable for correcting macronutrient and micronutrient deficiencies in plant life growing at such sites.

SUMMARY OF THE INVENTION
[0012] The present invention provides a process for preparing nano-fertilizer composition providing important plant nutrients for agricultural application without causing or limiting environmental hazard. The nano-fertilizer composition of the present invention is capable of slow release/controlled release of a plant nutrient inside plant system.
[0013] The present invention provides a process for preparation of nano-fertilizer composition comprises step of:
a) an aqueous solution of plant nutrient is prepared by dissolving plant nutrient in water;
b) an aqueous solution of synthetic polymer is prepared by dissolving polymer in water;
c) adding drop-wise the aqueous solution of the synthetic polymer to step (a) solution;
d) keeping the step (c) solution at 50-500 rpm for 15-20 minutes for uniform mixing at room temperature and atmospheric pressure; and
e) adding drop-wise the uniformly mixed solution of step (d) to an aqueous solution of cross-linking agent and uniformly mixing it for 25-30 minutes to obtain colloidal dispersion of nano-fertilizer.
[0014] In an embodiment of the present invention the synthetic polymer is polyethyleneimine (PEI) having molecular weight in the range of 5000 Da to 25000 Da.
[0015] In yet another embodiment of the present invention the ratio of percent plant nutrient: percent synthetic polymer (PEI) by weight is in the range from 1 to 2750 and the synthetic polymer concentration is varied from 0.02% to 1% wt./v.
[0016] In yet another embodiment of the present invention the cross-linking agent is selected from the group comprising of carboxylic acid polymer preferably polyacrylic acid or a copolymer of acrylic and maleic acid or a conventional molecule such as sodium triphosphate (STPP).
[0017] In yet another embodiment of the present invention the carboxylic acid cross linker is in the molecular weight range of 5000 Da to 70000 Da.
[0018] In yet another embodiment of the present invention nano-fertilizer can optionally be formed in PEI system without the presence of a cross-linking agent.
[0019] In yet another embodiment of the present invention, the present invention provides a nano-fertilizer composition preferably in form of an aqueous solution comprising plant nutrient trapped inside synthetic polymer nanoparticle, wherein the synthetic polymer nanoparticle is made by cross-linking of polyethyleneimine and acrylic acid polymer.
[0020] In yet another embodiment of the present invention the fertilizer is present in an amount 1% to 55% of the total weight of the nano-fertilizer composition and the size of the nanoparticle is in the range of 1-1000 nanometers.
[0021] In yet another embodiment of the present invention preferably the plant nutrient is urea.

BRIEF DESCRIPTION OF THE FIGURES
[0022] Figure 1 is a schematic diagram that shows the formation of nutrient nanoparticles encapsulated inside PEI-Sokolan PA25 cross-linked nanoparticle system.
[0023] Figure 2 is a Transmission electron micrographs for nano urea. The dark objects are nanoparticles.
[0024] Figure 3 shows the Field Emission Scanning Electron Microscopy (FE-SEM) image of nano urea and corresponding particle size distribution.
[0025] Figure 4 shows the dynamic light scattering data and zeta potential of the particles.

DESCRIPTION OF THE INVENTION
[0026] The following detailed description is presented to enable any person skilled in the art to make and use the invention. For purposes of explanation, specific nomenclature is set forth to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that these specific details are not required to practice the invention. Descriptions of specific applications are provided only as representative examples. The present application is not intended to be limited to the embodiments shown, but is to be accorded the widest possible scope consistent with the principles and features disclosed herein.
[0027] Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of skill in the art to which the disclosed method and compositions belong. It must be noted that as used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural reference unless the context clearly dictates otherwise. Thus, for example, reference to “a plant nutrient” includes “one or more” macro or micronutrient or a “plurality” of such nutrients.
[0028] Similarly, the words "comprise," "comprises," and "comprising" are to be interpreted inclusively rather than exclusively. Likewise, the terms "include," "including" and "or" should all be construed to be inclusive, unless such a construction is clearly prohibited from the context. However, the embodiments provided by the present disclosure may lack any element that is not specifically disclosed herein. Thus, a disclosure of an embodiment defined using the term "comprising" is also a disclosure of embodiments "consisting essentially of’ and "consisting of’ the disclosed components. Where used herein, the term "example," particularly when followed by a listing of terms, is merely exemplary and illustrative, and should not be deemed to be exclusive or comprehensive. Any embodiment disclosed herein can be combined with any other embodiment disclosed herein unless explicitly indicated otherwise.
[0029] As used herein, the term “nanoparticle” refers to any particle having an average diameter of less than 1000 nanometers (nm). In some embodiments, nanoparticles have an average diameter of less than 300 nm, less than 100 nm, less than 50 nm, less than 25 nm, less than 10 nm or less than 5 nm. In some embodiments, each nanoparticle has a diameter of less than 300 nm, less than 100 nm, less than 50 nm, less than 25 nm, less than 10 nm or less than 5 nm.
[0030] As used herein, the terms “nanoparticle formulation” or “nanoparticle composition” are used interchangeably with reference to any substance that contains at least one nanoparticle. In some embodiments, a nanoparticle formulation is a uniform collection of nanoparticles. Nanoparticle formulation could contain nanoparticles having diameters in a range from 1 nm to 1000 nm, 5 nm to 500 nm, 5 nm to 300 nm, 5 nm to 100 nm, 5 nm to 50 nm or below 5 nm. The nanoparticle formulation could also have a bi-modal size distribution where some particles could lie in a range of 5-50 nm and remaining could lie in the range of 50 nm to 1000 nm.
[0031] According to the embodiments herein, the term plant nutrient means mineral nutrients which include the broad class of macronutrient and micronutrient. The macronutrient further includes primary nutrient such as nitrogen (N), phosphorous (P) and potassium (K) and secondary nutrients such as calcium (Ca), magnesium (Mg) and sulfur (S). While micronutrients includes boron (B), copper (Cu), iron (Fe), chloride (Cl), manganese (Mn), molybdenum (Mo) and zinc (Zn).
[0032] In another embodiment of the present invention, a liquid formulation of nano fertilizer (nano urea, nano NPK or nano forms of other macro or micronutrients) can be applied through spray on leaves of plants. The nanoparticles enter the plant through the stomatal openings or cuticle and get absorbed in the plant system. The nanoparticles are further transported to different regions in the plant through the known mechanisms of nutrient transport inside plant.
[0033] Urea is widely used as a fertilizer and it is believed that more than 80% of the world's urea production is used as a fertilizer. It has the highest nitrogen content (46%) of all solid nitrogen based fertilizers used. Urea in the soil is converted to ammonia by hydrolysis. The ammonia is then oxidized to nitrates by the bacteria present in the soil. The nitrates are then absorbed by the plants for its nutrients. Urea is also used as a base for the manufacture of many other nitrogen based fertilizers.
[0034] According to the embodiments herein, synthetic polymers refer to oligomers and polymers containing amino groups, consideration is given, for example, to polyamines, polymeric polyamines, nitrogen-substituted vinyl polymers, polyoxazolines, polydiallyldimehtylammonium polymers, polyallylamine polymers, polypropylenimine and its dendrimers, polyethylenimine and its dendrimers, polyamidoamine and its dendrimers, and also copolymers and derivatives and combinations of two or more of the stated substances.
[0035] Preferred oligomers and polymers containing amino groups comprise polyamines and polymeric polyamines, polyalkylenimines such as polyethylenimines and polypropylenimines, for example, polyvinylamines, polyalkoxylated polyamines, ethoxylated polyamines, propoxylated polyamines, alkylated and benzylated polyamines, and also combinations of two or more of the aforementioned components.
[0036] Especially preferred for use are oligomers and polymers containing amino groups are polyethylenimines, polyethylenimine dendrimers, and also their copolymers, derivatives, and mixtures of at least two of these components.
[0037] Suitable polyethylenimines may comprise linear or branched polyethylenimine polymers or oligomers having for example 10 or more monomer units, and also their derivatives, analogs, copolymers, and mixtures of at least two of these components. Suitable polyethylenimines may preferably comprise branched polyethylenimine.
[0038] Polyethylenimine (PEI) is a polymer with repeating units composed of the amine group and two carbon aliphatic CH2CH2 spacers. Linear polyethyleneimines contain all secondary amines, in contrast to branched PEIs which contain primary, secondary and tertiary amino groups.

[0039] Polyethylenimines may be obtained through the polymerization of ethylenimine, and are available commercially on the market, in the form, for example, of the Lupasol® and Epomin® product families and there, in particular, in the form of the products Lupasol® G20, Lupasol® FG, Lupasol® G35, Lupasol® P, and Lupasol®1595 (the Lupasol® products are available from BASF (Florham Park, N.J., USA)), and also Epomin® SP-003, Epomin® SP-006, Epomin® SP-012, Epomin® SP-018, Epomin® SP-200, Epomin® SP-1000, and Epomin® SP-1050 (the Epomin® products are available from Nippon Shokubai (Osaka, Japan)).
[0040] In an embodiment of the present invention the first step in the process of the present invention is to prepare aqueous solution of plant nutrient by dissolving it in water. Second step involves preparation of aqueous solution of synthetic polymer polyethyleneimine (PEI) by dissolving it in water. It is followed by drop wise addition of aqueous solution of PEI to aqueous solution of plant nutrient. After complete addition of PEI solution to plant nutrient solution, the resultant mixture is stirred for sufficient time to ensure homogeneous solution. The homogenously mixed PEI-plant nutrient solution may optionally be added to cross-linking agent like polyacrylic acid (Sokalan PA-25) solution. After complete addition, the mixture is stirred for sufficient time. The resultant solution formed is colloidal dispersion of nanoparticles of urea. The pH of the colloidal suspension of nano-urea is in range from pH 4 to 6. For the purpose illustration by way of examples in the present invention Urea is obtained from Avra having specification of Mol. wt. 60.06 g/mol and density- 1.32 g/cm3. Lupasol WF is obtained from BASF having specification of Mol. wt. 25,000 g/mol, concentration upto 99% and density 1.10 g/cm3. Lupasol G-100 is obtained from BASF having specification of Mol. wt. 5,000 g/mol, concentration upto 50% and density 1.08 g/cm3. Sokalan PA-25 CL PN is obtained from BASF having specification Mol. wt. 4000 g/mol, concentration upto 49% and density 1.26 g/cm3. Sokalan CP 5 is obtained from BASF having specification Mol. wt. 70,000 g/mol, concentration upto 40% and density 1.30 g/cm3.
[0041] Mechanism: The presence of amine groups in the PEI molecule attracts nutrient molecules such as urea for example, which in water can have a delta negative (from oxygen in carbonyl) and delta positive charges on Nitrogen due to resonating structure. This leads to weak attachment of urea molecule to amine groups of PEI. Sokalan PA-25 acts as a cross-linking molecule, thus leading to the formation of PEI-Sokalan PA-25 cross linked nanoparticle, which has urea embedded inside the nanoparticle. Here polymer nanoparticle acts as a carrier of urea as illustrated in Figure 1. This process is applicable to other nutrients also and has been disclosed in examples below.
[0042] Thus, from the foregoing description, it will be apparent to one of the person skilled in the art that many changes and modifications can be made thereto without departing from the scope of the invention as set forth in the description. Accordingly, it is not intended that the scope of the foregoing description be limited to the description set forth above, but rather that such description be construed as encompassing such features that reside in the present invention, including all the features and embodiments that would be treated as equivalents thereof by those skilled in the relevant art.
[0043] The embodiments of the present invention are more particularly described in the following examples that are intended as illustrations only, since numerous modifications and variations within the scope of the present invention will be apparent to those of skill in the art. Unless otherwise noted, all parts, percentages and ratios reported in the following examples are on a weight basis and all reagents used in the examples were obtained or are available from the chemical suppliers.

[0044] Example 1: Process for formation of Nano-urea
[0045] To illustrate the process of the present invention urea is taken as plant nutrient. 10.8 g of urea powder is taken in a beaker and dissolved in 10 ml of distilled water. In another beaker, 0.011g of Lupasol WF (polyethyleneimine of Molecular weight = 25000 Da; commercial Lupasol WF contains 99% polymer by weight) is dissolved in 10mL distilled water. 10mL of Lupasol-WF solution is filled in burette and then added drop-wise to urea solution. After complete addition of Lupasol WF solution to urea solution, the resultant mixture is stirred for 15 minutes to ensure homogeneous solution. In the next step 20mL of Lupasol WF-Urea solution is added drop-wise to 80mL of 0.1% Sokalan PA-25 solution (polyacrylic acid with molecular weight of 4000 Da; commercial sokolan PA-25 contains 50% polymer by weight). After complete addition, the mixture is stirred for 30 minutes and the resultant solution formed is turbid looking colloidal dispersion of nano urea. It is observed that nanoparticles of urea are in range of around 1 -50 nm.
[0046] Transmission electron microscopy images recorded for nano urea samples obtained from Example 1 are shown in Figure 2. HR-TEM is carried out using JEOL JEM 2100 plus. The dark dots in the image are nanoparticles clearly showing the ultra-small size of nano urea (size range 1-30 nm). Scanning electron microscopy (SEM) image and corresponding particle size distribution are illustrated in Figure 3. SEM is carried out by using FEI Nova NanoSEM 450 instrument. Small white dots in the image of Figure 3 are nanoparticles of urea.
[0047] Figure 4 shows the dynamic light scattering data which shows a bimodal distribution of nanoparticles. This gives the hydrodynamic diameter of the nanoparticles. Data for zeta potential is also shown. The zeta potential of the particles is -42 mV indicating that the nanoparticles are negatively charged.

[0048] Example 2: Process for synthesis of 1000 lit (1 KL) of Nano-urea at pilot plant
[0049] In a 2 KL reactor, 840 litres of demineralized water is taken. To this is added 2.12 Kg of Sokolan PA25 solution slowly under stirring. The stirring was continued for another 30 minutes. To another reactor, 118 L of demineralized water is added and further 96 kg of powder or prilled technical/commercial grade bulk urea (N =46%) is added and kept under stirring until complete dissolution. Dissolution of urea could take anywhere from 2 hours to 12 hours depending on the quality of urea. In another container, 50 litres of demineralized water are taken and 105 grams of lupasol WF is added and stirred for 30 minutes. This solution is further added drop wise to urea solution under stirring. This urea-lupasol solution is then agitated for another 1 hour. After this, the lupasol-urea solution is added drop-wise to previously prepared sokolan solution. To increase the rate of addition the lupasol-urea solution is added to Sokolan through a spray nozzle atomizer. Air and liquid are fed to the spray nozzle and rate of addition in the form of atomized spray can vary from 0.1 L per minute to 1 litre per minute or more. After complete addition, the stirring is continued for another 1 hour. Resultant solution formed is turbid looking colloidal dispersion of nano urea. Subsequently, standard formulating agents are added to this nano urea solution to make the final formulation. The product is further bottled directly and can be shipped to the market after packaging.

[0050] Example 3: Process for synthesis of nano urea while varying the concentration of urea in the final formulation (1% urea to 55% urea)
[0051] 1% Urea:
a. In a beaker, 0.24g of urea powder is dissolved in 4mL distilled water. In another beaker, 0.0022g of Lupasol WF is dissolved in 2mL distilled water. 2mL of Lupasol-WF solution is filled in burette and then added drop-wise to urea solution. The solution is kept on stirring for uniform mixing and dissolution.
b. After complete addition of Lupasol WF solution to urea solution, the resultant mixture is stirred for 15 mins to ensure homogeneous solution.
c. Finally, 6mL of Lupasol WF- urea solution is added dropwise to 18mL of 0.1% Sokalan PA-25 solution.
d. After complete addition, the mixture is stirred for 30 mins and the resultant solution formed is colloidal dispersion of nanoparticles.

[0052] 5 % Urea:
a. In a beaker, 1.2g of urea powder is dissolved in 5mL distilled water. In another beaker, 0.0022g of Lupasol WF is dissolved in 2mL distilled water. 2mL of Lupasol-WF solution is filled in burette and then added drop-wise to urea solution. The solution is kept on stirring for uniform mixing and dissolution.
b. After complete addition of Lupasol WF solution to urea solution, the resultant mixture is stirred for 15 mins to ensure homogeneous solution.
c. Finally, 7mL of Lupasol WF- urea solution is added dropwise to 17mL of 0.1% Sokalan PA-25 solution.
d. After complete addition, the mixture is stirred for 30 mins and the resultant solution formed is colloidal dispersion of nanoparticles.

[0053] 10% Urea:
a. In a beaker, 2.4g of urea powder is dissolved in 10mL distilled water. In another beaker, 0.0022g of Lupasol WF is dissolved in 2mL distilled water. 2mL of Lupasol-WF solution is filled in burette and then added drop-wise to urea solution. The solution is kept on stirring for uniform mixing and dissolution.
b. After complete addition of Lupasol WF solution to urea solution, the resultant mixture is stirred for 15 mins to ensure homogeneous solution.
c. Finally, 12mL of Lupasol WF- urea solution is added dropwise to 12mL of 0.1% Sokalan PA-25 solution.
d. After complete addition, the mixture is stirred for 30 mins and the resultant solution formed is colloidal dispersion of nanoparticles.

[0054] 20% Urea:
a. In a beaker, 4.8g of urea powder is dissolved in 10mL distilled water. In another beaker, 0.0022g of Lupasol WF is dissolved in 2mL distilled water. 2mL of Lupasol-WF solution is filled in burette and then added drop-wise to urea solution. The solution is kept on stirring for uniform mixing and dissolution.
b. After complete addition of Lupasol WF solution to urea solution, the resultant mixture is stirred for 15 mins to ensure homogeneous solution.
c. Finally, 12mL of Lupasol WF- urea solution is added dropwise to 12mL of 0.1% Sokalan PA-25 solution.
d. After complete addition, the mixture is stirred for 30 mins and the resultant solution formed is colloidal dispersion of nanoparticles.

[0055] 30% Urea:
a. In a beaker, 7.2g of urea powder is dissolved in 10mL distilled water. In another beaker, 0.0022g of Lupasol WF is dissolved in 2mL distilled water. 2mL of Lupasol-WF solution is filled in burette and then added drop-wise to urea solution. The solution is kept on stirring for uniform mixing and dissolution.
b. After complete addition of Lupasol WF solution to urea solution, the resultant mixture is stirred for 15 mins to ensure homogeneous solution.
c. Finally, 12mL of Lupasol WF- urea solution is added dropwise to 12mL of 0.1% Sokalan PA-25 solution.
d. After complete addition, the mixture is stirred for 30 mins and the resultant solution formed is colloidal dispersion of nanoparticles.

[0056] 55% Urea:
a. In a beaker, 13.2g of urea powder is dissolved in 15mL distilled water. In another beaker, 0.0022g of Lupasol WF is dissolved in 2mL distilled water. 2mL of Lupasol-WF solution is filled in burette and then added drop-wise to urea solution. The solution is kept on stirring for uniform mixing and dissolution.
b. After complete addition of Lupasol WF solution to urea solution, the resultant mixture is stirred for 15 mins to ensure homogeneous solution.
c. Finally, 17mL of Lupasol WF- urea solution is added dropwise to 7mL of 0.1% Sokalan PA-25 solution.
d. After complete addition, the mixture is stirred for 30 mins and the resultant solution formed is colloidal dispersion of nanoparticles.

[0057] Example 4: Process for synthesis of nano urea while varying the initial (starting) concentration of Lupasol from 0.5% to 1%
[0058] 0.5% Lupasol:
a. In a beaker, 2.4g of urea powder is dissolved in 7mL distilled water. In another beaker, 0.0275g of Lupasol WF is dissolved in 5mL distilled water. 5mL of Lupasol-WF solution is filled in burette and then added drop-wise to urea solution. The solution is kept on stirring for uniform mixing and dissolution.
b. After complete addition of Lupasol WF solution to urea solution, the resultant mixture is stirred for 15 mins to ensure homogeneous solution.
c. Finally, 12mL of Lupasol WF- urea solution is added dropwise to 12mL of 0.1% Sokalan PA-25 solution.
d. After complete addition, the mixture is stirred for 30 mins and the resultant solution formed is colloidal dispersion of nanoparticles.

[0059] 1% Lupasol:
a. In a beaker, 2.4g of urea powder is dissolved in 7mL distilled water. In another beaker, 0.0555g of Lupasol WF is dissolved in 5mL distilled water. 5mL of Lupasol-WF solution is filled in burette and then added drop-wise to urea solution. The solution is kept on stirring for uniform mixing and dissolution.
b. After complete addition of Lupasol WF solution to urea solution, the resultant mixture is stirred for 15 mins to ensure homogeneous solution.
c. Finally, 12mL of Lupasol WF- urea solution is added dropwise to 12mL of 0.1% Sokalan PA-25 solution.
d. After complete addition, the mixture is stirred for 30 mins and the resultant solution formed is colloidal dispersion of nanoparticles.

[0060] Example 5: Process for synthesis of nano urea while varying the initial (starting) concentration of Sokolan PA 25: (Sokolan was varied from 0.5% to 1%)
[0061] Sokolan 0.5%:
a. In a beaker, 2.4g of urea powder is dissolved in 7mL distilled water. In another beaker, 0.0022g of Lupasol WF is dissolved in 2mL distilled water. 2mL of Lupasol-WF solution is filled in burette and then added drop-wise to urea solution. The solution is kept on stirring for uniform mixing and dissolution.
b. After complete addition of Lupasol WF solution to urea solution, the resultant mixture is stirred for 15 mins to ensure homogeneous solution.
c. Finally, 9mL of Lupasol WF- urea solution is added dropwise to 15mL of 0.5% Sokalan PA-25 solution.
d. After complete addition, the mixture is stirred for 30 mins and the resultant solution formed is colloidal dispersion of nanoparticles.

[0062] Sokolan 1%:
a. In a beaker, 2.4g of urea powder is dissolved in 7mL distilled water. In another beaker, 0.0022g of Lupasol WF is dissolved in 2mL distilled water. 2mL of Lupasol-WF solution is filled in burette and then added drop-wise to urea solution. The solution is kept on stirring for uniform mixing and dissolution.
b. After complete addition of Lupasol WF solution to urea solution, the resultant mixture is stirred for 15 mins to ensure homogeneous solution.
c. Finally, 9mL of Lupasol WF- urea solution is added dropwise to 15mL of 1% Sokalan PA-25 solution.
d. After complete addition, the mixture is stirred for 30 mins and the resultant solution formed is colloidal dispersion of nanoparticles.

[0063] Example 6: Process for synthesis of nano urea by varying polymer molecular weights (PEI molecular weight is varied from 5000 to 25000 Da; and Sokolan molecular weight is varied from 5000 to 70,000 Da)
[0064] Using 0.1% Lupasol-WF + 0.1% Sokalan CP-5
Lupasol WF Molecular weight = 25000 Da; Sokolan CP5 (a co-polymer of acrylic acid and maleic acid): Molecular weight: 70,000 Da.
a. In a beaker, 0.011g of Lupasol-WF is dissolved in 10mL distilled water.
b. In another beaker, 10 grams of urea is dissolved in 10 mL of distilled water.
c. Lupasol solution is added dropwise to urea solution and stirred for 15 minutes.
d. In another beaker, 0.26g Sokalan CP-5 is dissolved in 80mL distilled water.
e. Then 20mL Urea-Lupasol-WF solution is added drop-wise to 80mL Sokalan CP-5 solution.
f. After complete addition, the mixture is stirred for 30 mins and the resultant solution formed is colloidal dispersion of nanoparticles.

[0065] Using 0.02% Lupasol G-100 + 0.02% Sokalan CP-5
Lupasol G -100: Molecular weight = 5000 Da; Sokolan CP5: Molecular weight: 70,000 Da.
a. In a beaker, 0.00432g of Lupasol G-100 is dissolved in 10mL distilled water.
b. In another beaker, 10 grams of urea is dissolved in 10 mL of water.
c. Lupasol solution is added drop wise to urea solution and kept for stirring for 15 minutes.
d. In another beaker, 0.052g Sokalan CP-5 is dissolved in 80mL distilled water.
e. Then 20mL Urea-Lupasol G-100 solution is added drop-wise to 80mL Sokalan CP-5 solution.
f. After complete addition, the mixture is stirred for 30 mins and the resultant solution formed is colloidal dispersion of nanoparticles.

[0066] Example 7: Process for synthesis of nano urea by using a conventional cross-linking agent such as sodium triphosphate (STPP) instead of Polyacrylic acid (Sokolan) crosslinking polymer
a. In a beaker, 1.9g of urea powder is dissolved in 5mL distilled water. In another beaker, 0.0011g of Lupasol WF is dissolved in 10mL distilled water. 10mL of Lupasol-WF solution is filled in burette and then added drop-wise to urea solution. The solution is kept on stirring for uniform mixing and dissolution.
b. After complete addition of Lupasol WF solution to urea solution, the resultant mixture is stirred for 15 mins to ensure homogeneous solution.
c. Finally, 4mL of 0.5% STPP solution is added dropwise to 15mL of urea-Lupasol-WF solution.
d. After complete addition, the mixture is stirred for 30 mins and the resultant solution formed is clear.
e. Subsequently, 3 drops of 10% HCl solution was added to achieve a turbid colloidal dispersion of stable urea nano-particles.

[0067] Example 8: Process for synthesis of nano diammonium phosphate (DAP)
a. In a beaker, 12g of DAP powder is dissolved in 10mL distilled water. In another beaker, 0.011g of Lupasol WF is dissolved in 10mL distilled water. 10mL of Lupasol-WF solution is filled in burette and then added drop-wise to DAP solution. The solution is kept on stirring for uniform mixing and dissolution.
b. After complete addition of Lupasol WF solution to DAP solution, the resultant mixture is stirred for 15 mins to ensure homogeneous solution.
c. Finally, 20mL of Lupasol WF- DAP solution is added dropwise to 100mL of 0.1% Sokalan PA-25 solution.
d. After complete addition, the mixture is stirred for 30 mins and the resultant solution formed is clear.
e. On addition of 1mL 30% aqueous solution of ammonium hydroxide (NH4OH) solution, the resultant solution is colloidal dispersion of nano-particles and stable.

[0068] Example 9: Process for synthesis of nano Monoammonium phosphate (MAP) in the absence of cross-linking agent
a. In this process MAP itself acts as a polymer cross-linking agent.
b. In a beaker, 10g of MAP powder is dissolved in 20mL distilled water.
c. Then MAP solution is added drop-wise to 80mL 0.1% Lupasol-WF solution. The solution is kept on stirring for uniform mixing and dissolution.
d. After complete addition, the mixture is stirred for 30 mins and the resultant solution formed is colloidal dispersion of nanoparticles.

[0069] Example 10: Process for synthesis of nano Monopotassium phosphate (MKP) in the absence of cross-linking agent
a. In this process MKP itself acts as a polymer cross-linking agent.
b. In a beaker, 10g of MKP powder is dissolved in 20mL distilled water.
c. Then MKP solution is added drop-wise to 80mL 0.1% Lupasol-WF solution. The solution is kept on stirring for uniform mixing and dissolution.
d. After complete addition, the mixture is stirred for 30 mins and the resultant solution formed is colloidal dispersion of nanoparticles.

[0070] Example 11: Process for synthesis of nano Dipotassium phosphate (DKP) in the absence of cross-linking agent
a. In this process DKP itself acts as a polymer cross-linking agent.
b. In a beaker, 10g of DKP powder is dissolved in 20mL distilled water.
c. Then DKP solution is added drop-wise to 80mL 0.1% Lupasol-WF solution. The solution is kept on stirring for uniform mixing and dissolution.
d. After complete addition, the mixture is stirred for 30 mins and the resultant solution formed is colloidal dispersion of nanoparticles.

[0071] Example 12: Synthesis of nano NPK mixture
This process involves individually making nano urea, nano MKP and nano MAP and then blending it together to form a Nano NPK mixture as per NPK ratio desired. Here Nano NPK 5-5-5 preparation is demonstrated:
[0072] Nano-urea nano-particles:
a. In a beaker, 6.6g of urea powder is dissolved in 2.5mL distilled water. 2.5mL of 0.1% Lupasol-WF solution is filled in burette and then added drop-wise to urea solution. The solution is kept on stirring for uniform mixing and dissolution.
b. After complete addition of Lupasol WF solution to urea solution, the resultant mixture is stirred for 15 mins to ensure homogeneous solution.
c. Finally, 5mL of Lupasol WF-Urea solution is added dropwise to 25mL of 0.1% Sokalan PA-25 solution.
d. After complete addition, the mixture is stirred for 30 mins and the resultant solution formed is colloidal dispersion of nanoparticles.

[0073] Nano-DKP and Nano-MAP nano-particles:
a. In a beaker, 5.7g of DKP powder and 1.2g of MAP powder was dissolved in 30mL 0.1% Lupasol-WF solution.
b. After complete dissolution, the mixture is stirred for 30 mins and the resultant solution formed is colloidal dispersion of nanoparticles.

c. Once all nano-particles are formed individually, 30mL of nano-DKP and nano-MKP solution is added to 30mL nano-urea solution.
d. The resultant solutions are stirred on for 30 mins for homogeneous mixing of the solutions.

[0074] Example 13: Process for synthesis of nano calcium
a. In a beaker, 12g of calcium nitrate powder is dissolved in 10mL distilled water. In another beaker, 0.011g of Lupasol WF is dissolved in 10mL distilled water. 10mL of Lupasol-WF solution is filled in burette and then added drop-wise to calcium nitrate solution. The solution is kept on stirring for uniform mixing and dissolution.
b. After complete addition of Lupasol WF solution to calcium nitrate solution, the resultant mixture is stirred for 15 mins to ensure homogeneous solution.
c. Finally, 20mL of Lupasol WF- Ca(NO3)2 solution is added dropwise to 100mL of 0.1% Sokalan PA-25 solution.
d. After complete addition, the mixture is stirred for 30 mins and the resultant solution formed is colloidal dispersion of nanoparticles with some precipitate formed.
e. On addition of 1mL 10% HCl solution, the colloidal dispersion is stable.

[0075] Example 14: Process for synthesis of Nano-magnesium
a. In a beaker, 12g of magnesium sulphate powder is dissolved in 10mL distilled water. In another beaker, 0.011g of Lupasol WF is dissolved in 10mL distilled water. 10mL of Lupasol-WF solution is filled in burette and then added drop-wise to magnesium sulphate solution. The solution is kept on stirring for uniform mixing and dissolution.
b. After complete addition of Lupasol WF solution to magnesium sulphate solution, the resultant mixture is stirred for 15 mins to ensure homogeneous solution.
c. Finally, 20mL of Lupasol WF- MgSO4 solution is added dropwise to 100mL of 0.1% Sokalan PA-25 solution.
d. After complete addition, the mixture is stirred for 30 mins and the resultant solution formed is colloidal dispersion of nanoparticles with some precipitate formed.
e. On addition of 1mL 10% HCl solution, the colloidal dispersion is stable.

[0076] Example 15: Process for the synthesis of nano – boron
a. In a beaker, 12g of borax powder is dissolved in 10mL warm distilled water. In another beaker, 0.011g of Lupasol WF is dissolved in 10mL distilled water. 10mL of Lupasol-WF solution is filled in burette and then added drop-wise to borax solution. The solution is kept on stirring for uniform mixing and dissolution.
b. After complete addition of Lupasol WF solution to borax solution, the resultant mixture is stirred for 15 mins to ensure homogeneous solution.
c. Finally, 20mL of Lupasol WF- borax solution is added dropwise to 100mL of 0.1% Sokalan PA-25 solution.
d. After 12 hrs a turbid colloidal dispersion of nanoparticles of boron can be seen.

[0077] From the foregoing it will be observed that numerous modifications and variations can be effectuated without departing from the scope of the novel concepts of the present invention. It is to be understood that no limitations with respect to the specific embodiments illustrated is intended or should be inferred. It should be understood that all such modifications and improvements have been deleted herein for the sake of conciseness and readability but are properly within the scope of the following claims.