PROCESS FOR THE PRODUCTION OF PRECIPITATED SINGLE PHASE CRYSTALLINE 1-D NANOSCALED CALCITE

Abstract

A process is provided for the production of precipitated single-phase crystalline 1-D nanoscaled calcite (CaCO3). This process utilizes natural plant extracts, specifically from Hyphaene thebaica fruit, as a chelating agent. The method involves combining a source of calcium cations, typically calcium chloride (CaCl2), with a source of carbon dioxide (CO2) in a solvent of water (H2O). The natural extract acts as a bio-catalyst, facilitating the formation of crystalline CaCO3 with unique properties. The process is distinguished by its avoidance of synthetic chelating agents, pH control chemicals, and additional thermal treatments, making it a green and sustainable approach to CaCO3 production. The calcite demonstrates notable shape anisotropy and elevated porosity, attributes that are beneficial in various applications.

Claims

1. A process for the production of precipitated single-phase crystalline 1-D nanoscaled calcite (CaCO3), the process comprising: providing a source of calcium cations; providing a source of carbon dioxide (CO2); providing a solvent in the form of water (H2O); providing a natural extract obtained from a plant species as a chelating agent; and extracting the precipitate, wherein the natural extract is obtained from Hyphaene thebaica fruit.

2. The process of claim 1, wherein the calcium cations are obtained from calcium chloride (CaCl2) and wherein the calcium chloride (CaCl2) is added to a filtered extract solution and stirred for 24 hours at room temperature with gentle stirring.

3. The process of claim 1 further comprising adding CO2 via bubbling and allowing the precipitate to settle.

4. The process of claim 1, wherein the precipitate is collected by centrifugation for 10 to 30 minutes at 3,000 rpm to 5,000 rpm.

5. The process of claim 1 further comprising washing the precipitate thrice in deionized water (dH2O) and subsequent centrifugation for 5 to 15 minutes at 3,000 rpm to 5,000 rpm.

6. The process of claim 1, wherein no additional catalyst, chemicals for pH control, or thermal treatment is used during or after the biosynthesis process.

7. A product obtained by the process of claim 1 for use in cement binder applications.

8. A product obtained by the process of claim 1 for use as a nano-fertilizer.

9. A product obtained by the process of claim 1 for use as a drug carrier in the health sector.

10. A product obtained by the process of claim 1 for use as a white pigment.

11. The process of claim 1, wherein a resulting product is used in an emulsion stable in water for application to the surfaces of plants to provide sun blocking characteristics.

12. The process of claim 11, wherein the resulting product is diluted in water and applied to an area with a spraying device.

13. The process of claim 1, wherein the calcite has a high reflectivity within the visible (VIS) and Near Infrared (NIR) solar spectral regions.

14. The process of claim 1, wherein the calcite is tested as a bio/nano-fertilizer in the growth of Lycopersicum esculentum (Tomato), with the concentration of the CaCO3 product fixed at 0.01, 0.03, and 0.05 g/l.

15. The process of claim 1, wherein the bio-engineered CaCO3 nanorods improve the workability and mechanical strength of cement composites due to their fine particle size and porosity.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0031] A process to produce precipitated single phase crystalline 1-D nano-scaled Calcite in accordance with the invention will now be described by way of the following, non-limiting examples with reference to the accompanying drawing. In the drawings:

[0032] FIG. 1(a)-1(f) show a typical High Resolution Transmission Electron Microscopy (HRTEM) and Selected Area Electron Diffraction (SAED) of the bio-engineered CaCO.sub.3 of the present invention;

[0033] FIG. 2 shows a typical Scanning Electron Spectroscopy (EDS) profile of the bio-engineered nano-scaled CaCO.sub.3 of the present invention;

[0034] FIG. 3(a) shows a Thermo-Gravimetry Analysis (TGA) of the bio-engineered nano-scale CaCO3 within the thermal range of 25-850 C. of the present invention;

[0035] FIG. 3(b) shows the corresponding Differential Scanning calorimetry (DSC) profile within the thermal range of 25-900 C. of the present invention;

[0036] FIG. 4(a) shows results of room temperature Fourier Transform Infrared spectroscopy spectrum of the bioengineered nano-scale CaCO.sub.3 within the spectral range of 400-4000 cm.sup.1 of the present invention;

[0037] FIG. 4(b) shows an exploded view on the spectral region of 400-1000 cm.sup.1 reporting the characteristic Raman active modes of Calcite (CaCO.sub.3) at 288 cm.sup.1 (L.sub.Calcite) and 161 cm.sup.1 (T.sub.Calcite);

[0038] FIG. 5(a) shows room temperature Raman spectrum of the bio-engineered CaCO.sub.3 nanoparticles within the range of 0-1200 cm.sup.1 of the present invention;

[0039] FIG. 5(b) shows an exploded view on the spectral region of 100-370 cm.sup.1 reporting the CaO characteristic vibrational mode of Calcite Ca CO.sub.3 of the present invention;

[0040] FIG. 6 shows room temperature photoluminescence of the bio-synthesized nanoscaled CaCO3 as well as the intermediary product of Ca(OH).sub.2 and the initial precursor CaCl.sub.2) in accordance with the present invention;

[0041] FIGS. 7(a)-7(d) show the -2 X-rays diffraction spectra within the angular range of (a) 20-50 degree and (b) 55-85 degrees, (c) Full XRD profile with the MAUD simulation and (d) Proposed Calcite crystallographic structure of the bio-engineered CaCO.sub.3 1-D nanoparticles in accordance with the present invention;

[0042] FIG. 8(a) shows a standard diffuse reflectance spectrum under normal incidence of the bio-engineered CaCO.sub.3 1-D nanoparticles within the spectral range of 200-1000 nm; highlighting the elevated reflectivity within the VIS & NIR solar spectrum.

[0043] FIG. 8(b) shows an exploded view of FIG. 8(a) which corresponds on the UV-Bleu spectral region of 200-345 nm;

[0044] FIGS. 9(a)-9(c) show the evolution versus the bio-engineered CaCO.sub.3 1-D nanoparticles using nutrient concentration of (a) the average of plant's height, (b). the average number of leaves and (c) the average days to flowering relatively to the control sample; highlighting the efficacy as a potential green fertilizer.

[0045] FIGS. 10(a)-10(c) show multi-scale porosity in the bio-engineered CaCO.sub.3 1-D nanoparticles.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046] In regard to light scattering & white pigment applications, FIG. 8(a) displays the standard diffuse reflectance spectrum under normal incidence of the bioengineered CaCO3 nanoparticles (in their pelletised powder form) within the spectral range of 200-1000 nm. FIG. 8(b) further displays the corresponding zoom on the UV-Bleu spectral region of 200-345 nm, therefore such an elevated reflectivity within the visible (VIS) & Near infrared (NIR) solar spectral regions is a characteristic of highly reflecting solar materials equivalent to that of standard white pigments including BaSO4, ZnO & TiO2. In view of the aforementioned, one could safely conclude that the bio-engineered CaCO3 nanoparticles of the present invention could be a potential compound for white pigment coatings' applications.

[0047] In regard to nanofertilizing, Calcium is a crucial plant nutrient playing a vital role in maintaining plant cellular metabolism. As a biocatalyst becoming functional through Calcium ionic species, these Calcium ionic species are concerned with hydrocarbons metabolism, maintenance of cellular membranes, leaf morphology, physiology of membrane, protein production. In view of investigating the effectiveness of the currently bio-engineered CaCO3 nanoparticles, they were tested as a bio/nano-fertilizer in the case of Lycopersicum esculentum (Tomato). The concentration of the CaCO3 product of the present invention was fixed at a concentration of 0.01, 0.03 and 0.05 g/l and compared to the control. Accordingly, the average plant's height, the average number of leaves as well as the average number of days to flowering were collected. Experimental parameters were similar to the following publication: N.Jabeen, Q. Maqbool, T. Bibi, M. Nazar, S. Z. Hussain, T. Hussain, T. Jan, I. Ahmad, M. Maaza, S. Anwaar, Optimised synthesis of ZnO-nano-fertiliser through green chemistry: boosted growth dynamics of economically important L. esculentum, IET NanobiotechnologyVol. 12 Iss. 4, pp. 405-411 (2018).

[0048] FIG. 9(a) displays the evolution of the average of plant's height versus the CaCO3 nutrient concentration. One conclusion is that the plant's height is higher than that of the control one for each of the CaCO3 nutrient's concentration especially for the lowest value of 0.01 g/l. A similar behaviour is observed for the average number of leaves vs nutrient concentration (FIG. 9(b). FIG. 9(c) seems to be of a special interest. It indicates that the average days to flowering is lower with the CaCO3 nutrient concentration relatively to the control sample. Especially for the 0.01 g/l, the flowering is 24 days before the control. As a pre-conclusion, the plant's growth parameters are far competitive relatively to the control especially for the lowest concentration of 0.01 g/l which seems the optimal value within these conditions of experimentation.

[0049] In regards to cement binder applications, As per FIGS. 1(a)-1(f), the bio-engineered CaCO3 is nano-scaled in size, and hence has a finer particles size as compared to the Ordinary Portland Cement (OPC) particles (which is in the range of 10 m in average). This fine aspect would likely improve the particle packing of concrete and give a superior spacer effect. Also, the concrete with CaCO3 replacement as per the present invention possess a higher slump, which increases the workability. In addition, in a statistical spatial distribution, the 1-D morphology of the CaCO3 nanoparticles of the present invention would favour if not enhance the local mechanical strength of the CaCO3/Cement composite as a local reinforcer. Furthermore, the porosity of the CaCO3 nanorods (FIG. 10) could favour an enhanced binding in view of the high surface to volume of the individual porous CaCO3 nanorods of the present invention.

[0050] Furthermore, the general TGA & DSC variations/trends of the bio-engineered CaCO3 of the present invention are equivalent to that of bulk CaCO3 but with a significant shift to lower temperatures. More accurately, the decomposition and phase transition temperature are 648.8 C. instead of 750 C. for Bulk. This is likely due to the high surface to volume ratio of the current nanoscaled CaCO3 of the present invention comparatively to their bulk equivalent. This would improve its workability within the cement composite.