OXIDATIVE METHOD FOR PREPARING A FERTILIZING COMPOSITION

Abstract

The invention relates to a method for preparing a fertilizing composition, comprising a step of treating a liquid composition having humic substances the weight-average hydrodynamic radius of the particles in solution of which, measured by dynamic light scattering (DLS), is the “Hr.sub.average pre-treatment” with an appropriate amount of oxidizing agent to obtain a liquid composition having oxidized humic substances the weight-average hydrodynamic radius of the particles in solution (Hr.sub.average post-treatment) of which, measured by DLS, is greater than the Hr.sub.average pre-treatment; a composition that can be obtained by the method and the use thereof.

Claims

1. A method for preparing a fertilizing composition, comprising a step of treating a liquid composition having humic substances the weight-average hydrodynamic radius of the particles in solution of which, measured by dynamic light scattering (DLS), is the “Hr.sub.average pre-treatment” with an appropriate amount of oxidizing agent to obtain a liquid composition having oxidized humic substances the weight-average hydrodynamic radius of the particles in solution (Hr.sub.average post-treatment) of which, measured by DLS, is greater than the Hr.sub.average pre-treatment.

2. The method according to claim 1, said liquid composition having humic substances is obtained from peat, leonardite, lignite, coal or anthracite.

3. The method according to claim 1, said liquid composition having humic substances comprises at least 50% by dry weight of humic substances.

4. The method according to claim 1, said oxidizing agent is selected from ozone, ultraviolet rays and/or hydrogen peroxide.

5. The method according to claim 1, said Hr.sub.average post-treatment is at least 5 times higher than the Hr.sub.average pre-treatment.

6. The method according to claim 1, characterized in that the weight proportion of particles in solution having a hydrodynamic radius comprised between 15 nm and 10000 nm of the composition having oxidized humic substances, measured by DLS, is at least 2 times greater than the weight proportion of particles in solution having a hydrodynamic radius comprised between 15 nm and 10000 nm of the composition having humic substances before oxidation.

7. A fertilizing composition that can be obtained by the method according to claim 1.

8. The fertilizing composition according to claim 7, characterized in that the weight-average hydrodynamic radius of the particles in solution (Hr.sub.average), measured by DLS, is greater than 50 nm.

9. The composition according to claim 7, characterized in that the weight proportion of particles in solution having a hydrodynamic radius comprised between 15 nm and 10000 nm, measured by DLS, is greater than 15%.

10. The composition according to claim 7, further comprising one or more mineral fertilizers, preferably containing one or more minerals selected from nitrogen, phosphorus, potassium, calcium, magnesium and sulfur.

11. A stimulant comprising the composition according to claim 7 for the absorption of minerals in a plant, preferably the minerals are selected from nitrogen, phosphorus, potassium, calcium, magnesium and/or sulfur.

12. A stimulant comprising the composition according to claim 7 for the production of pigments in a plant, preferably the production of carotenoids, chlorophyll A and/or chlorophyll B.

13. The stimulant according to claim 11, for stimulating aerial and/or root growth of the plant.

14. A method for fertilizing a plant, a soil or a growing medium comprising applying the composition according to claim 7 to the plant, to said soil or to said growing medium.

15. A method for fertilizing a plant, a soil or a growing medium consisting of: preparing a fertilizing composition by implementing the method according to claim 1, and applying said fertilizing composition to the plant, to the soil or to the growing medium.

16. The method according to claim 14, characterized in that the application to the plant, to the soil or to the growing medium allows to stimulate the absorption of minerals in a plant and/or to stimulate the production of pigments in the plant.

17. The method according to claim 14, characterized in that the composition is applied to an acid soil.

18. The stimulant according to claim 12, for stimulating aerial and/or root growth of the plant.

Description

DESCRIPTION OF FIGURES

[0108] FIG. 1 is an HPSEC curve which shows the evolution of the weight-average molar weight in solution (Mw) of the liquid composition having humic substances during the treatment with ozone. The figure also shows the evolution of the number-average molecular Weight (Mn) of the liquid composition having humic substances during treatment with ozone.

[0109] FIG. 2 is an HPSEC curve which shows the evolution of the weight-average molar weight in solution (Mw) of the liquid composition having humic substances as a function of the ratio “ozone weight/humic substance weight”. The figure also shows the evolution of the Number-Average Molecular Weight (Mn) of the liquid composition having humic substances as a function of the ratio “ozone weight/humic substance weight”.

[0110] FIG. 3 shows the oxidative method for degrading humic substances with ozone.

[0111] FIG. 4 illustrates the assembly of a batch reactor used for the ozonation of a liquid composition having humic substances.

[0112] FIG. 5 is an HPSEC profile of a composition having ozonated humic substances (parent composition of Example 1) and a composition having non-ozonated humic substances (control composition of Example 1). The solid line shows the ozonated composition and the dotted line shows the non-ozonated control composition.

[0113] FIG. 6 is a histogram obtained from the HPSEC data of FIG. 5 which shows the percentage of the different families of humic substances according to their molecular weight.

[0114] FIG. 7 is a DLS (Dynamic light scattering) analysis that shows the change in size of humic substances with increasing amounts of ozone. The figure shows the appearance of molecules of humic substances with a larger hydrodynamic radius (Hr) (particle families 2 and 3) with a ratio ozone weight/humic substance weight (R) equal to 0.1, R=0.5 and R=2. With R=8, a degradation of large humic substances (family 3) into smaller molecules (families 1 & 2) is observed.

[0115] FIG. 8A is a histogram obtained from the DLS data in FIG. 7 that shows the weight distribution of humic substances as a function of their hydrodynamic radius (Hr) with increasing amounts of ozone. The figure shows that the weight proportion of particles in solution with a size comprised between 15 nm and 10000 nm increases when the ratio ozone weight/humic substance weight (R) is equal to 0.1, R=0.5 and R=2.

[0116] FIG. 8B is a histogram obtained from the DLS data in FIG. 7 that shows the weight-average hydrodynamic radius of particles in solution (Hr.sub.average) with increasing amounts of ozone. The figure shows that the Hr.sub.average increases when the ratio ozone weight/humic substance weight (R) is equal to 0.1, R=0.5 and R=2.

[0117] FIG. 9 is a curve which compares the evolution of the length of the leaves of maize treated with a composition having ozonated humic substances (1.5×2+SN) and a composition having non-ozonated humic substances (T×2+SN).

[0118] FIG. 10 shows the average length of the leaves of maize treated with a composition having ozonated humic substances (1) and a composition having non-ozonated humic substances (0).

[0119] FIG. 11 is a curve which compares the evolution of the length of the roots of maize treated with a composition having ozonated humic substances (1.5×2+SN) and a composition having non-ozonated humic substances (T×2+SN).

[0120] FIG. 12 shows the average length of the roots of maize treated with a composition having ozonated humic substances (1) and a composition having non-ozonated humic substances (0).

[0121] FIG. 13 is a histogram which compares the length of the roots of maize treated with a composition of minerals, a composition having non-ozonated humic substances (T×2+SN), a composition having ozonated humic substances with a ratio “ozone weight/humic substance weight” of 0.5 (0.5×2+SN), a composition having ozonated humic substances with a ratio “ozone weight/humic substance weight” of 1.5 (1.5×2+SN) and a composition having ozonated humic substances with a ratio “ozone weight/humic substance weight” of 3.5 (3.5×2+SN).

[0122] FIG. 14 is a histogram comparing the carotenoid content of maize leaves treated with a composition having ozonated humic substances (left) and a composition having non-ozonated humic substances (right).

[0123] FIG. 15 is a histogram comparing the chlorophyll A content of maize leaves treated with a composition having ozonated humic substances (left) and a composition having non-ozonated humic substances (right).

[0124] FIG. 16 is a histogram comparing the chlorophyll B content of maize leaves treated with a composition having ozonated humic substances (left) and a composition having non-ozonated humic substances (right).

[0125] FIG. 17 is an HPSEC profile of a liquid composition having non-ozonated humic substances before and after freeze-drying.

[0126] FIG. 18 is an HPSEC profile of a liquid composition having ozonated humic substances before and after freeze-drying.

[0127] FIG. 19 is a curve showing the precipitation of humic substances as a function of pH in a liquid composition having ozonated humic substances (in solid lines) and in a liquid composition having non-ozonated humic substances (in dotted lines).

EXAMPLES

Example 1: Materials and Methods

[0128] Method for Preparing a Fertilizing Composition

[0129] A liquid composition having humic substances was obtained by diluting 11 grams of a potassium salt powder of humic substances (Dralig® product marketed by the company Humatex—CAS 68514-28-3) in 20 liters of water, to obtain 20 liters of a composition with a concentration of humic substances of 550 mg/L. This liquid composition having humic substances was used in the examples below as “control composition”.

[0130] The ozonation reaction was carried out in a conventional batch reactor described in FIG. 4. The reactor used was a simple glass bottle (1) containing 1 L of the composition having humic substances at 550 mg/L (2). This solution was stirred with a magnetic stirrer (3). The ozone was produced with an ozonizer (CFS1—Ozonia) supplied by pure oxygen (4). The ozone concentration used was 20 g/m.sup.3 in the gas flow entering the reactor (with a flow rate of 1.67×10.sup.−2 g/min of ozone) and was monitored using the ozone analyzer (5). The flow of gas entering the reactor was regulated at 50 L/h using a flow meter (6). The temperature of the incoming gas was measured with a thermometer (7) and was comprised between 17 and 22° C. The gas was injected into the composition having humic substances with a glass inlet and a sinter including pores of an average size of 200 μm (8). The excess ozone was then destroyed in a second reactor (9) containing a 50 g/L solution of potassium iodide (KI) (10). A valve was used in order to control the reaction (11). When the ozone was not used in the reactor, it was sent directly to the destroyer (9).

[0131] The ozonation time was 50 minutes for 1 L of composition having humic substances at 550 mg/L.

[0132] The pH of the composition having humic substances thus treated with ozone was then adjusted to pH=7.0 with a 0.1 mol/L hydrochloric acid solution and, if necessary, with a 0.1 mol/L sodium hydroxide solution.

[0133] Compositions having ozonated humic substances were diluted one quarter with MilliQ water. The liquid composition having humic substances thus obtained was used in the examples below as “parent composition”.

[0134] DLS Measurements

[0135] DLS measurements were performed with a Dynapro Nanostar (WYATT technology) equipped with a laser (λ=662 nm). The measured scatter intensity range was 1.36×10.sup.6 to 3.14×10.sup.6 counts per second (cps). All measurements were taken at a 90° detection angle and all sizes reported are averages of 15 sequences of 5 seconds each. The reproducibility of the samples was analyzed 3 times. 20 μL of each solution was used and all solutions were adjusted to 25° C. in the sample chamber of the instrument and allowed to equilibrate for 5 min. A disposable microcuvette (WYATT technology) was used to perform the DLS measurement. Dynamics software (WYATT technology) was used to control the acquisition of measurements and analyze the data.

Example 2: Characterization of the Fertilizing Composition

[0136] The compositions having control humic substances (that is to say before ozonation) and ozonated according to Example 1 (parent composition) were analyzed by HPSEC. This analysis was made using a Dionex Ultimate 3000 channel equipped with a TSK G2000SW.sub.XL column (Phenomenex, USA—7.5×300 mm). The channel had an automatic sampler and an isocratic pump. Two detectors were used: a UV-Visible detector with a detection wavelength set at 254 nm (analysis of C═C double bonds) and an R Optilab T-rEX detector (WYATT Technology). The eluent used was a 10 mM acetic acid/sodium acetate mixture with the pH fixed at 7. The eluent was filtered at 0.45 μm and 0.1 μm. The flow rate used was 1 mL/min. The sample injection volume was 20 μL.

[0137] The control composition and the parent composition were also analyzed by DLS

[0138] (Dynamic light scattering). DLS is an analytical technique based on the Brownian motion of particles, described by the Stokes-Einstein equation. It has been used to study the aggregation of humic substances. In addition, the DLS allowed to determine the hydrodynamic radius (Hr) and the polydispersity of humic substances in solution.

[0139] DLS experiments were performed with a Dynapro Nanostar 22 (WYATT technology) equipped with a laser (λ=662 nm). The measured scattering intensity range was 1.36×10.sup.6-3.14×10.sup.6 counts per second (cps). All measurements were taken at a 90° detection angle and all sizes reported are averages of 15 sequential runs of 5 seconds each. Samples were analyzed 26 times for reproducibility. 20 μL of each composition was used and all solutions were adjusted to 25° C. in the measuring chamber and allowed to equilibrate for 5 min. A disposable microcuvette (WYATT technology) was used to perform the DLS analysis. Dynamics software (WYATT technology) was used to control the acquisition of measurements and analyze the data.

[0140] HPSEC results with RI detector are shown in FIGS. 1 and 2 (Mw and Mn) and FIGS. 5 and 6. DLS results are shown in FIGS. 7 and 8.

[0141] Mw and Mn

[0142] FIGS. 1 and 2 show the evolution of Mw and Mn during treatment with ozone.

[0143] HPSEC with Ri Detector

[0144] FIG. 5 shows that ozonation leads to a structural modification of humic substances. With regard to the aggregates, it is seen that the signal increases (around 5.2 minutes), which attests to the solubilization of certain molecules. The peak at 6 min is degraded in favor of several populations relating to smaller molar weights (at 6.6; 7.0; 7.7 and 8.9 minutes). It should be noted that the peak at 10 minutes corresponds to all the small molecules (size <100 Da) in particular the salts contained in the mobile phase of the HPLC.

[0145] FIG. 6 shows the different percentages of the different families of humic substances according to the molecular weight. FIG. 6 demonstrates an appearance of compounds with a molar weight greater than 170 kDa in the parent composition, whereas with the control composition, this family of molecules is not observed. FIG. 6 also shows that ozonation leads to the formation of smaller humic substance molecules.

[0146] DLS

[0147] FIG. 7 is a DLS (Dynamic light scattering) analysis that shows the change in size of humic substances with increasing amounts of ozone. The figure shows the appearance of molecules of humic substances with a larger hydrodynamic radius (Hr) (particle families 2 and 3) with a ratio ozone weight/humic substance weight (R) equal to 0.1, R=0.5 and R=2. With R=8, a degradation of large humic substances (family 3) into smaller molecules (families 1 & 2) is observed.

[0148] FIG. 8A is a histogram obtained from the DLS data in FIG. 7 that shows the weight distribution of humic substances as a function of their hydrodynamic radius (Hr) with increasing amounts of ozone. The figure shows that the weight proportion of particles in solution with a size comprised between 15 nm and 10000 nm increases when the ratio ozone weight/humic substance weight (R) is equal to 0.1, R=0.5 and R=2.

[0149] FIG. 8B is a histogram obtained from the DLS data in FIG. 7 that shows the weight-average hydrodynamic radius of particles in solution (Hr.sub.average) with increasing amounts of ozone. The figure shows that the Hr.sub.average increases when the ratio ozone weight/humic substance weight (R) is equal to 0.1, R=0.5 and R=2.

[0150] It is deduced from FIGS. 7, 8A and 8B, in particular from FIG. 8B, that the amount of ozone necessary to have an R=0.1, an R=0.5 and an R=2 corresponds to an appropriate amount of ozone within the meaning of the invention. On the other hand, the amount of ozone necessary to have an R=8 does not correspond to an appropriate amount of ozone within the meaning of the invention.

Example 3: Effects on Plant Growth

[0151] Materials and Methods

[0152] Several compositions have been prepared:

[0153] Composition “1.5×2+SN” (ozonated humic substances): 10 liters of parent composition (Example 1) were supplemented with hydroponic solutions, namely 2.5 mL of a solution of nitrogen, phosphorus and potassium (FloraGro® from General Hydroponics), 2.5 mL of a nitrogen and calcium solution (FloraMicro® from General Hydroponics) and 2.5 mL of a solution of phosphorus, potassium, magnesium and sulfur (FloraBloom® from General Hydroponics).

[0154] Composition “T×2+SN” (non-ozonated humic substances): 10 liters of control composition (Example 1) were supplemented with hydroponic solutions, namely 2.5 mL of a nitrogen, phosphorus and potassium solution (FloraGro® from General Hydroponics), 2.5 mL of a nitrogen and calcium solution (FloraMicro® from General Hydroponics) and 2.5 mL of a phosphorus, potassium, magnesium and sulfur solution (FloraBloom® from General Hydroponics).

[0155] The composition of the FloraMicro, FloraGro and FloraBloom solutions added in the compositions of humic substances is shown in tables 2 to 4 below respectively.

TABLE-US-00002 TABLE 2 Composition of FloraMicro solution (NPK: 5-0-1). Total Nitrogen (N) 5.0% Ammoniacal nitrogen 1.5% Nitric nitrogen 3.5% Soluble potassium (K.sub.2O) 1.3% Boron (B) 0.01% Calcium (CaO) 1.4% EDTA chelated copper (Cu) 0.01% 6% EDTA—11% DPTA chelated iron (Fe) 0.12% EDTA chelated manganese (Mn) 0.05% Molybdenum (Mo) 0.004% EDTA chelated zinc (Zn) 0.015%

TABLE-US-00003 TABLE 3 Composition of FloraGro solution (NPK: 3-1-6). Total Nitrogen (N) 3% Ammoniacal nitrogen 1% Nitric nitrogen 2% Available phosphate (P.sub.2O.sub.5) 1% Soluble potassium (K.sub.2O) 6% Soluble magnesium (MgO) 0.8%

TABLE-US-00004 TABLE 4 Composition of FloraBloom solution (NPK: 0-5-4). Available phosphate (P.sub.2O.sub.5) 5% Soluble potassium (K.sub.2O) 4% Soluble magnesium (MgO) 3% Soluble sulfur (SO.sub.4) 5%

[0156] On D0, 400 maize seeds of the Amaretto variety were placed on vermiculite soaked in water in the dark for 48 hours at 30° C., in order to initiate germination.

[0157] On D2, the germinated seeds were placed in hydroponic culture according to 2 modalities (200 seeds per modality): [0158] Modality 1:35 mL of composition “1.5×2+SN” [0159] Modality 0:35 mL of composition “T×2+SN”

[0160] The hydroponic cultures were maintained for 16 days, with a renewal of the compositions every 2-3 days.

[0161] Results

[0162] Length of the Leaves

[0163] The length of the leaves was measured at each renewal of the compositions and at D16. The results are shown in FIG. 9. The average length of the leaves at D17 is shown in FIG. 10.

[0164] The results were analyzed statistically (Analysis of the differences between the modalities with a confidence interval at 95%) according to the ANOVA test. The calculations are presented in Tables 5 and 6.

TABLE-US-00005 TABLE 5 Statistical analyzes/Tukey (HSD)/Analysis of the differences between the modalities with a confidence interval at 95% (length of the leaves). Differ- Standardized Critical Pr > Sig- Contrast ence difference value Diff nificant 1 vs 0 3.576 4.381 1.972 <0.0001 Yes Critical value of Tukey's d 2.789 Lower Upper Estimated Standard bound bound Modality average error (95%) (95%) 1 30.632 0.584 29.480 31.784 0 27.055 0.570 25.931 28.179

TABLE-US-00006 TABLE 6 Statistical analyzes/Newman-Keuls (SNK)/Analysis of the differences between the modalities with a 95% confidence interval (length of the leaves). Differ- Standardized Critical Pr > Sig- Contrast ence difference value Diff nificant 1 vs 0 3.576 4.381 1.972 <0.0001 Yes Lower Upper Estimated Standard bound bound Modality average error (95%) (95%) 1 30.632 0.584 29.480 0 27.055 0.570 25.931 31.784 28.179

[0165] The results show that the length of the leaves is significantly greater with the composition comprising ozonated humic substances, compared to the composition comprising non-ozonated humic substances.

[0166] It was also shown that the leaf area increased significantly with the composition comprising ozonated humic substances, compared to the composition comprising non-ozonated humic substances (results not shown).

[0167] Length of the Roots

[0168] The length of the roots was measured at each renewal of the compositions and at D17. The results are shown in FIG. 11. The average length of the leaves at D17 is shown in FIG. 12.

[0169] The results were analyzed statistically (Analysis of the differences between the modalities with a confidence interval at 95%) according to the ANOVA test. The calculations are shown in Tables 7 and 8.

TABLE-US-00007 TABLE 7 Statistical analyzes/Tukey (HSD)/Analysis of the differences between the modalities with a confidence interval at 95% (length of the roots). Differ- Standardized Critical Pr > Sig- Contrast ence difference value Diff nificant 1 vs 0 2.508 3.524 1.972 <0.001 Yes Critical value of Tukey's d 2.789 Lower Upper Estimated Standard bound bound Modality average error (95%) (95%) 1 14.356 0.509 13.352 15.361 0 11.849 0.497 10.869 12.829

TABLE-US-00008 TABLE 8 Statistical analyzes/Newman-Keuls (SNK)/Analysis of the differences between the modalities with a confidence interval at 95% (length of the roots). Differ- Standardized Critical Pr > Sig- Contrast ence difference value Diff nificant 1 vs 0 2.508 3.524 1.972 <0.001 Yes Lower Upper Estimated Standard bound bound Modality average error (95%) (95%) 1 14.356 0.509 13.352 15.361 0 11.849 0.497 10.869 12.829

[0170] The results show that the length of the roots is significantly greater with the composition comprising ozonated humic substances, compared to the composition comprising non-ozonated humic substances.

Example 4: Influence of the Amount of Ozone

[0171] Several compositions have been prepared: [0172] Composition “1.5×2+SN” (ozonated humic substances ratio 1.5): see Example 3. [0173] Composition “0.5×2+SN” (ozonated humic substances ratio 0.5): corresponds to the composition “1.5×2+SN” except that the humic substances were ozonated with a ratio ozone weight/humic substance weight of 0.5. [0174] Composition “3.5×2+SN” (ozonated humic substances ratio 3.5): corresponds to the composition “1.5×2+SN” except that the humic substances were ozonated with a ratio ozone weight/humic substance weight of 3.5. [0175] Composition “T×2+SN” (non-ozonated humic substances): see Example 3

[0176] On D0, 80 maize seeds of the Amaretto variety were placed on vermiculite soaked in water in the dark for 48 hours at 30° C., in order to initiate germination.

[0177] On D2, the germinated seeds were placed in hydroponic culture according to 4 modalities (20 seeds per modality): [0178] 35 mL of composition “0.5×2+SN” [0179] 35 mL of composition “1.5×2+SN” [0180] 35 mL of composition “3.5×2+SN” [0181] 35 mL of composition “T×2+SN”.

[0182] The hydroponic cultures were maintained for 16 days, with a renewal of the compositions every 2-3 days.

[0183] Results

[0184] Length of the roots was measured at D14. The results are shown in FIG. 13.

[0185] The results show that the length of the roots increases with the increase in the ratio ozone weight/humic substance weight.

[0186] Example 5: Effects on Photosynthetic Activity

[0187] The plants obtained in Example 3 were used to measure the chlorophyll and carotenoid content of the leaves by UV-Visible spectrophotometry.

[0188] Material and Methods

[0189] 0.5 g of crushed leaves (mortar crushing) were placed in two vial tubes of 1 mL each. 4.5 mL of 100% MeOH solution was added to the first tube. 4.5 mL of MeOH/3% KOH solution (0.3 g of KOH diluted in 10 mL of 100% MeOH) was added to the second tube. The two tubes were then vortexed then left in ice for 15 minutes. The tubes were then centrifuged at 10000 RPM for 10 min at 4° C.

[0190] The content of each tube was deposited on a 96-well plate in 6 replicas of 300 μL per well (that is to say 6×300 μL for tube 1 and 6×300 μL for tube 2).

[0191] The absorbance of each well was measured by TECAN and analyzed on the “Tecan control” software according to the following conditions: [0192] Tube with 100% MeOH: reading at 663 nm, 645 nm and 470 nm [0193] Tube with MeOH/3% KOH: reading at 472 nm and 508 nm.

[0194] The carotenoid and chlorophyll A and B contents were measured according to the following equations:

Carotenoids (in μg/mL)=(A.sub.472×1724.3−A.sub.508×2450.1)/270.9

Chlorophyll A (in μg/mL)=16.72×A.sub.663−9.16×A.sub.645

Chlorophyll B (in μg/mL)=34.09×A.sub.645−15.28×A.sub.663

[0195] Results

[0196] The results are shown in FIGS. 14 to 16 and in Table 9 below.

TABLE-US-00009 TABLE 9 Chl-A Chl-B Chl-A + B Carotenoids With ozonation 3.550 0.731 4.280 1.127 Without 2.976 0.625 3.601 1.038 ozonation Pr > F <0.0001 <0.0001 <0.0001 <0.0001 Significant Yes Yes Yes Yes

[0197] The results show that the carotenoid and chlorophyll contents increase when the maize is treated with the composition comprising ozonated humic substances, compared to the composition comprising non-ozonated humic substances.

Example 6: Physico-Chemical Analyzes of Control and Ozonated Humic Substances

[0198] Effect of Freeze-Drying

[0199] The purpose of freeze-drying is to determine whether the transition to the solid state of ozonated humic substances induces intra and inter molecular rearrangement. If so, it can be deduced that the molecules should be used in solution and not in the form of solids.

[0200] Protocol

[0201] 15 mL of the “control” and “parent” compositions of Example 1 were freeze-dried. The freeze-dried compositions were then dissolved in 15 mL of MilliQ water. The solutions thus obtained were then analyzed by HPSEC.

[0202] HPSEC Results

[0203] FIG. 17 shows the curves obtained for the non-ozonated composition. The figure shows that the curves are similar, the two profiles being relatively close. Freeze-drying has little influence on non-ozonated humic substances (figure below).

[0204] In the case of ozonated humic substances (FIG. 18), differences similar to those obtained with non-ozonated humic substances were obtained. There was an 8 second lag between the two curves. In addition, the intensity of the peak at 8 min was greater after freeze-drying for ozonated humic substances. Apart from these differences, the curves are similar.

[0205] The humic substances ozonated according to the method of the invention are very stable and withstand freeze-drying. The ozonated humic substances according to the invention can therefore be prepared both in liquid form and in solid form (freeze-dried form) without alteration.

[0206] Solubility of Humic Substances as a Function of pH

[0207] Protocol

[0208] The “control” and “parent” compositions of Example 1 were used. The compositions were placed in vials and acidified with increasing volumes of 0.1 mol/L HCl. The vials were weighed beforehand empty (m.sub.vial). All the acidified compositions were then stirred then centrifuged. The pellets and the supernatants were separated, the pH of the supernatant was measured, the pellet itself was dried in an oven. The vials were then weighed with the pellet (m.sub.pellet+m.sub.vial). The weighings were made once the samples returned to room temperature.

[0209] For each sample, the weight percentage of humic substances was calculated according to the following formula:

% SH.sub.by weight=((m.sub.pellet+m.sub.vial)−m.sub.vial)×100/m.sub.initial SH [0210] with: [0211] % SH.sub.by weight=% of insoluble humic substances [0212] m.sub.pellet=weight of the pellet [0213] m.sub.vial=weight of the empty vial [0214] m.sub.initial SH=weight of humic substances placed in the vial before acidification.

[0215] Results

[0216] pH was measured for all samples. Except for the sample without HCl addition for which the difference is significant (3 pH units), the other pH values were relatively close to each other for the same volume of HCl added.

[0217] FIG. 19 shows that the more the solution was acidified, the more the humic substances tended to precipitate. However, the non-ozonated humic substances were precipitated up to 60% while the ozonated humic substances were only precipitated at 30%. Ozonation therefore improved the solubility of humic substances in acid pH.

BIBLIOGRAPHY

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