FORM 2
The Patents Act, 1970,
(39 of 1970)
&
The Patents Rule, 2003
Complete Specification
(See Section 10 rule 13),
Rashtriya Chemicals and Fertilizers Limited
(A Government of India Undertaking)
R&D-Bio & Agro Research Priyadarshini, Eastern Express Highway, Sion, Mumbai-400022
A method for development of nano sized urea embedded in nano hydroxyapatite,

Field of invention,
The field of invention relates to a method for development of nanosized urea, more particularly the field of invention relates to a method for development nano sized hydroxyapatite coating on the nanosized urea, thus providing embedded urea,
Background of invention and prior art,
The consumption of nitrogen fertilizer in India has been increasing hastily, whilst the nitrogen use efficiency (NUE) of cropping systems has been decreasing. It may have led to increase environmental losses, threatening the quality of air, soils, and fresh waters, and thereby endangering climate-stability, ecosystems, and human-health. It is expected that that the fertilizer consumption of India may double by 2050, there is an urgent need for scientific research to support better nitrogen management in Indian agriculture (Moring Andrea et aI; Frontiers in Sustainable Food Systems, February, 2021). Urea also forms 82 per cent of the total nitrogenous fertilizers consumed in India, with an annual consumption of 33.6 million tonnes in 2019-20 (FAO; The Fertilizer Sector). Numerous attempts to increase the NUE have so far met with little success, and the time may have come to apply nanotechnology to solve some of these problems.
A Nanofertilizer is a product made with nanoparticles or uses nanotechnology to improve nutrient use efficiency. Nano urea can be obtained through various methods viz. use of spinning cone reactor, combustion synthesis or spray drying. All these methods allow for the production of nano urea at high rates with higher efficacy.
A nanofertilizer refers to a product that delivers nutrients to crops in the following ways. The nutrient can be encapsulated inside nanomaterials such as nanotubes or nanoporous materials, coated with a thin protective polymer film, or delivered as particles or emulsions of nanoscale dimensions. Three classes of nanofertilizers have been proposed-nanoscale fertilizer, nanoscale additives, nanoscale coating. Owing to a high surface area to volume ratio, the effectiveness of nanofertilizers may surpass the most innovative polymer-coated conventional fertilizers (Maria C. DeRosa, et al; Nature Nanotechnology, February, 2010).
Apatite is a group of phosphate minerals, usually referring to hydroxyapatite, fluorapatite and chlorapatite, with high concentrations of OH-, F- and Cl ions, respectively, in the crystal.
Hydroxyapatite, also called hydroxylapatite (HA), is a naturally occurring mineral form of calcium apatite with the formula Ca5(PO4)3(OH), but it is usually written Ca10(PO4)6(OH)2 to denote that the

crystal unit cell comprises two entities. Hydroxyapatite is the hydroxyl end member of the complex apatite group. The OH- ion can be replaced by fluoride, chloride or carbonate, producing fluorapatite or chlorapatite.
United States Patent 8,696,784 discloses a fertilizer composition wherein a nitrogen containing macronutrient is adsorbed on the surface of hydroxyapatite phosphate nanoparticles. Said fertilizer composition slowly releases the nitrogen containing macronutrient to soil.
Indian Patent Application 4382/DELNP/2009 discloses nanourea dispersion A) comprising crosslinked nanourea particles a) and at least one dispersing medium B) which has at least one, preferably two group(s) reactive towards isocyanate groups, the water fraction, based on dispersion A) being 0% to 5% by weight.
Dispersions for the purposes of the present invention are A) compositions of matter which are composed of finely divided particles in a dispersing medium B). A feature of these mixtures is that phase separation does not take place; instead, at room temperature, the particles are stably distributed in the dispersing medium. The particles here are composed of solids; the dispersing medium may be solid or liquid at room temperature.
Another, Indian Patent Application No. 202121010603 discloses nutrient composition comprising an effective nitrogen and/ phosphate as principal ingredients in nanoscale dimension with or without other macro and micro nutrient required by plants for their growth and development.
Thus, it is found effective to use nano sized nutrient composition effectively without excess loss and efficient use of the fertilizer, nutrients, therefore it is object of the present invention to provide a nanosized fertilizer composition,
Object of the invention,
It is an object of the present invention to provide a method for development of nanosized urea,
It is also an object of the present invention to provide a method for Hydroxyapatite nanoparticles which were synthesised using an aqueous solution of Calcium hydroxide and orthophosphoric acid for providing coating of nano urea,
it is also an object of the present invention to provide a method for development nano sized hydroxyapatite coating on the nanosized urea.

It is also an object the present invention to provide Nano Urea embedded with hydroxyapatite which has been tested for its agronomic efficacy on various crops in in-house pot and field trials.
It is also an object of the present invention to provide stable molecules of nano Urea with greater agronomic efficiency.
Summary of the invention,
In one of the important aspects of the invention a method for development of nano sized urea embedded in nano Hydroxyapatite is provided in the said method Nano Urea Hydroxyapatite is coated with nano sized urea particles in proportion of 0.5: 0.1 to 100:20. The solution thus formed is spray dried at temperature between 40 - 80 °C with a flow rate of 0.01 ml/ minute to 20 ml/minute. The spray dried solids are further solubilized with demineralized water in a proportion of 0.05 to 10 gm / 20-40 ml. The dispersion of this solution is carried through ultrasound sonicator between 40 kHz to 70 kHz for a period between 1 hour to 9 hours to get the particle size of urea between 50- to 80 nm.
Detailed Description of invention,
In one of the preferred mode of the invention the synthesis of nano sized Urea is developed, the said method of conversion of urea to nano urea form have been adopted to achieve the stable nano sized urea with particle size between 70-80 nm.
Nano urea can be applied through fertigation/ drenching/ foliar spray.
In one of the most important mode of the invention it is provided a method synthesis of Urea embedded with hydroxyapatite which has been tested for its agronomic efficacy on various crops in in-house pot and field trials.
The said method involves following steps as,
I. Synthesis of Nano Urea Hydroxyapatite
(i) The synthesis has been carried out in different steps:
Hydroxyapatite nanoparticles were synthesised using an aqueous solution of Calcium hydroxide and orthophosphoric acid. A suspension of Calcium hydroxide 1- 20 % is prepared and allowed to mix for 30 minutes to 5 hours. The Orthophosphoric acid with concentration 0 .1M to 50 M was added drop wise to 1-20% suspension of Calcium hydroxide with continuous stirring at 100-2000 rpm for a period of 10 minutes to 8 hours. The resulting solution was stored at temperatures between l-20°Cfor 2-48 Hours to obtain the nanoparticles.

(ii) The process utilized for conversion of urea into nano sized urea is based on the use of anticoagulant, reducing, emulsifying and annealing agent citric acid, tri sodium citrate
For obtaining the nano sized Urea, 2 to 60 % Urea molecules are blended with 0.5 % to 12.50 % Trisodium Citrate/citric acid under temperature between 10 - 80 ° C. The heating is carried out for a period of 10 minutes to 3 hours. The Urea-Nitrogen is analysed with the help of p-dimethylaminobenzaldehyde (PDAB) method (yellow colour method).
(iii) The nano sized hydroxyapatite is coated with nano sized urea particles in proportion of 0.5: 0.1 to 100:20. The solution thus formed is spray dried at temperature between 40-80 °C with a flow rate of 0.01 ml/minute to 20 ml/minute. The spray dried solids are further solubilized with demineralized water in a proportion of 0.05 to 10 gm / 20-40 ml. The dispersion of this solution is carried through ultrasound sonicator between 40 kHz to 70 kHz for a period between 1 hour to 9 hours to get the particle size of urea between 50- to 80 nm.
In the other mode of the invention, it is provided that the use of the embedded nano urea with nano sized hydroxyapatite provides an excellent efficient result, in terms of increases in yield of crops on which it is tested, thus found an advantage in comparison with nano urea or other forms of urea, the results obtained are as discussed below,
Agronomic efficacy:
A. Pot Trials: Foliar application
1. Effect of Nano sized urea spray on spinach (Spinacia oleracea L)
Recommended dose of Fertilizer (N: P2O5: K2O): 40:40:40 Kg/ha
Table 1: Treatment details and percent yield increase due to application of Nano urea Hydroxyapatite

Dose Treatment Percentage Yield
Tl T.: 100 % RDF + 1 % SPRAY NU* 61.63
T2 T2: 50 % RDF+ 1% SPRAY NU 15.99
T3 T3: 100 % RDF + 2 % SPRAY NU 71.07
T4 T4: 50 % RDF + 2 % SPRAY NU 101.57
T5 T5: CONTROL (100 % RDF) —
*NU-NanoUrea


■i
Result: The treatment where 50 % RDF + 2 % SPRAY NU was applied recorded highest percent yield increment (101.57%).
2. Effect of Nano Urea spray on spinach (Spinocio oleracea L.)
In this trial the Nano Urea embedded Nano Hydroxyapatite was diluted and applied to crops through
Foliar spary
Recommended dose of Fertilizer (N: P2O5: K2O): 40:40:40 Kg/ha
Table 1: Treatment details of Nano urea Hydroxyapatite
Results: The treatment T8: 50% Recommended dose of fertilizers with 5% dilution spray of Nano Urea embedded nano hydroxyapatite exhibited maximum yield with increase of 15.18% as compared to control i.e. T9 :100% Recommended dose of fertilizers.
i B. Field Trials Details
1. Effect of Nano Urea Hydroxyapatite spray on Okra {Abelmoschus esculentus L.)

Recommended dose of Fertilizer (N: P2O5: K2O): 150:50:50 Kg/ha
Variety - Shankar Bhendi Ankur 2338
Table 1: Treatment details of Nano Urea Hydroxyapatite

Treatment Yield % Increase
Tl: Absolute control 800
T2: 100% RDF 1347.3
T3: 100% N through Nano-Urea drenching 1469.8 9.09
T4: 80% RDN through prilled Urea and one drenching of Nano-Urea 1570.7 16.52
T5: 60% RDN through prilled Urea and Two drenching of Nano-Urea 1620.31 20.26
T6: 100% N through Nano-Urea spray 1488.4 10.47
T7: 80% RDN through' prilled Urea and one spray of Nano-Urea 1590.9 18.08
T8: 60% RDN through prilled Urea and Two spray of Nano-Urea 1821.44 35.19
Results: The Treatment-T8: 60% Recommended dose of Nitrogen and two foliar spray of Nanourea
embedded Nano hydroxyapatite has revealed maximum yield of Okra with an increase of 35.19% as
compared with the treatment T2:100% Recommended dose of fertilizer.
C
Nano urea results on biter gourd Momordica charantia L.

treatment details Yield % Increase
Tl:100% RDF + Foliar 2652.83 47.49
T2:50% RDF + Foliar 2758.00 53.33
T3:100 % RDF + Drenching 2479.87 37.87
T4: 50 % RDF + Drenching 2363.50 31.40
T5: 100% RDF 1798.63
T6: 50 % RDF 1975.10 9,81
Results: Treatment -T2: 50 % Recommended dose of fertilizer + Foliar spray of Nano urea embedded nano hydroxyapatite recorded highest yield OF 53.33 % over control treatment T5:100% RDF

Examples,
I. Synthesis of Nano Urea Hydroxyapatite
Hydroxyapatite nanoparticles were synthesised using an aqueous solution of Calcium hydroxide and orthophosphoric acid. A suspension of Calcium hydroxide 1- 20 % is prepared and allowed to mix for 30 minutes to 5 hours. The Orthophosphoric acid with concentration 0 .1M to 50 M was added drop wise to 1 - 20 % suspension of Calcium hydroxide with continuous stirring at 100-2000 rpm for a period of 10 minutes to 8 hours. The resulting solution was stored at temperatures between 1 - 20 ° C for 2-48 Hours,to obtain the nanoparticles.
II. Method for obtaining nanosized urea
the nano sized Urea is prepared by blending 2 to 60 % Urea molecules are blended with 0.5% to 12.50 % Trisodium Citrate or citric acid under temperature between 10 - 80 ° C. The heating is carried out for a period of 10 minutes to 3 hours.
III. Method of embedding nano urea with hydroxyapatite,
The nano sized hydroxyapatite is coated with nano sized urea particles in proportion of 0.5: 0.1 to 100:20. The solution thus formed is spray dried at temperature between 40 - 80 °C with a flow rate of 0.01 ml/ minute to 20 ml/minute. The spray dried solids are further solubilized with demineralized water in a proportion of 0.05 to 10 gm / 20-40 ml. The dispersion of this solution is carried through ultrasound sonicator between 40 kHz to 70 kHz for a period between 1 hour to 9 hours to get the particle size of urea between 50- to 80 nm.

We claim,
l.A method for development of embedded nano sized urea with Hydroxyapatite comprising,
(i) providing nanosized Hydroxyapatite nanoparticles,
(ii) conversion of urea into nanosized urea,
(iii) coating nano sized urea particles with nano sized hydroxyapatite thus providing embedded nanosized urea.
2. A method for development of embedded nano sized urea with Hydroxyapatite according to claim 1 wherein Hydroxyapatite nanoparticles is prepared reacting aqueous solution of Calcium hydroxide and orthophosphoric acid.
3. A method for development of embedded nano sized urea with Hydroxyapatite according to claim 1 wherein nano sized is obtained by blending Urea, 2 to 60 % with 0.5 % to 12.50 % Trisodium Citrate/citric acid at the temperature between 10 - 80 ° C. for the period of 10 minutes to 3 hours.
4. A method for development of embedded nano sized urea with Hydroxyapatite according to claim 1 wherein hydroxyapatite is coated with nano sized urea particles in proportion of 0.5: 0,1 to 100:20 to obtain a dispersion,
5. A method for development of embedded nano sized urea with Hydroxyapatite according to claim 1 or 4 wherein dispersion is spray dried at temperature between 40 - 80 °C with a flow rate of 0.01 ml/ minute to 20 ml/minute.
6.A method for development of embedded nano sized urea with Hydroxyapatite according to claim 1 or 4 wherein spray dried solids are solubilized with demineralized water in a proportion of 0.05 to 10 gm/20-40 ml.
7. A method for development of embedded nano sized urea with Hydroxyapatite according to any of preceding claims the'dispersion is further agitated in an ultrasound sonicator between 40 kHz to 70 kHz for a period between 1 hour to 9 hours to get the particle size of embedded nano urea between 50- to 80 nm.