Physicochemical properties of a microelement fertilizer with amino acids

Article abstract of DOI:10.1134/S1070427207030020

The physicochemical properties of the initial components and products were studied with the aim of production of a microelement fertilizer with an amino acid concentrate. The physicochemical properties of the amino acid concentrate and its influence on the stability and sorption properties of fertilizers enriched in microelements were studied.

Full text of DOI:10.1134/S1070427207030020

ISSN 1070-4272, Russian Journal of Applied Chemistry, 2007, Vol. 80, No. 3, pp. 352 357. Pleiades Publishing, Ltd., 2007.
Original Russian Text R. Paleckiene, A. Sviklas, R. Šlinkšiene, 2007, published in Zhurnal Prikladnoi Khimii, 2007, Vol. 80, No. 3, pp. 353 359.
INORGANIC SYNTHESIS
AND INDUSTRIAL INORGANIC CHEMISTRY
Physicochemical Properties of a Microelement Fertilizer
with Amino Acids
R. Paleckiene, A. Sviklas, and R. Šlinkšiene
Kaunas Technological University, Kaunas, Lithuania
Received June 19, 2006
Abstract The physicochemical properties of the initial components and products were studied with the aim
of production of a microelement fertilizer with an amino acid concentrate. The physicochemical properties
of the amino acid concentrate and its influence on the stability and sorption properties of fertilizers enriched
in microelements were studied.
DOI: 10.1134/S1070427207030020
Intensification of agriculture requires using not
only effective mineral fertilizers containing macro-
and microelements [1, 2], but also physiologically
active substances, growth stimulants. In the past years,
much attention was given to testing as growth stimu-
lants various synthetic and natural physiologically
active substances: citric acid, humates, amino acids,
etc. [3 6].
by chemical and physicochemical methods of anal-
ysis. The nitrogen concentration was determined by
standard methods [13, 14]. The solid substances were
examined by IR spectroscopy, thermal analysis, and
X-ray phase analysis [15 18]. The IR spectra were re-
corded on a Spectrum GX FTIR spectrometer (Perkin
Elmer); samples were prepared as KBr pellets. Ther-
mal analysis was performed by differential scanning
calorimetry (DSC) with a Du Pont Instruments 990
The use of amino acids is most often recommended
under critical conditions of plant growth: after trans-
plantation, in the flowering period, and also at climat-
ic stresses (night frosts, drought) or plant diseases.
Amino acids are particularly effective in fertilizers
when used in combination with microelements [7 12].
1
Thermal Analyzer at a heating rate of 10 deg min .
X-ray phase analysis was performed with a DRON-6
diffractometer (Ni-filtered Cu radiation, range of
diffraction angles 0 166.5 , relative error 0.5%).
Naturamin-WSP amino acid concentrate was pre-
pared by chemical hydrolysis of proteins, collagen,
and keratin. The chemical formula of the product de-
pends on the ratio of free amino acids and oligopep-
tides. Naturamin-WSP product is a concentrate of
water-soluble amino acids containing 80% free amino
acids and 12.8% nitrogen; the total weight fraction of
organic matter is 90%.
In this study we examined the physicochemical
properties of the amino acid concentrate (AAC) and
its effect on the stability and sorption properties of
fertilizers enriched in microelements.
As AAC we used Naturamin-WSP product
DAYMSA, Spain), and as fertilizer, ARVI-micro
(
product (ARVI and Co., Lithuania) containing ammo-
nium sulfate and microelements.
Naturamin-WSP concentrate is a homogeneous
mixture of microgranules; it contains 17 amino acids
in amounts shown in Fig. 1.
The compositions of substances were determined
cAA, wt %
Fig. 1. Content of amino acids c
in Naturamin-WSP: (D) aspartic acid, (E) glutamic acid, (S) serine, (G) glycine, (H) histi-
AA
dine, (R) arginine, (T) threonine, (A) alanine, (P) proline, (Y) tyrosine, (V) valine, (M) methionine, (I) isoleucine, (L) leucine,
F) phenylalanine, (K) lysine, and (C) cysteine.
(
352

PHYSICOCHEMICAL PROPERTIES OF A MICROELEMENT FERTILIZER
353
We studied gravimetrically [13] the sorption of
water on AAC under ambient conditions (20 22 C,
humidity 25 37%) and in a desiccator over water
I, arb. units
(
21 C, humidity 98%). The dynamic curves of
water sorption by AAC are shown in Fig. 5.
Under ambient conditions (Fig. 5, curve 1), AAC
takes up a small amount of water (up to 5% in
6
9 days). Small oscillations of the dynamic curves
2
, deg
arise from fluctuations of the ambient temperature and
humidity. In a desiccator over water, AAC concentrate
absorbs water more actively. Point a in curve 2 cor-
responds to the limiting content of water after which
AAC starts to dissolve. Point b corresponds to the
appearance of mold. Thus, AAC is a hydrophilic sub-
stance, and the water absorption depends on the hu-
midity of the medium. This property should be evalu-
ated when using amino acids in production of mineral
fertilizers.
Fig. 2. X-ray diffraction pattern of Naturamin-WSP amino
acid concentrate: (I) intensity and (2 ) Bragg angle; the
same for Fig. 6.
The X-ray diffraction pattern of Naturamin-WSP
is shown in Fig. 2; the TG and DSC curves, in Fig. 3;
and the IR spectrum, in Fig. 4.
The X-ray diffraction pattern of ACC amino acids
Fig. 2) is typical of amorphous compounds. Only the
reflections at 1.443 and 0.449 nm of similar intensity
are pronounced; other reflections cannot be identified.
(
For agrochemical and economic reasons, we pre-
pared fertilizers based on ARVI microfertilizer and
Naturamin-WSP AAC. ARVI microfertilizer contain-
ing 14% nitrogen consists of ammonium sulfate and
microcomplex (Mg, S, Mn, Cu, Zn, B, Mo). To this
substance we added 1, 3, and 4% AAC and mechani-
cally mixed the components. Therefore, it was neces-
sary to study possible interactions between the com-
ponents and the stability of the composition. The
separate components, ARVI microfertilizers, and
ARVI microfertilizers with various additions of AAC
were subjected to X-ray diffraction, thermal, and IR
analyses (Figs. 6 8).
The DSC and TG curves of ACC (Fig. 3) show
that, starting from 70 C, Naturamin-WSP loses mois-
ture (TG curve) and remains virtually stable up to
2
10 C. At 214.1 C, a pronounced endothermic effect
is observed, followed by weight loss. Further heating
causes decomposition of the substance (DSC curve
exhibits exothermic peaks at 339.0 and 350.0 C, and
endothermic peaks at 293.5 and 305.4 C). In the crys-
talline state, amino acids exist in the form of bipolar
ions; their IR spectra (Fig. 4) are similar irrespective
of the position of carboxy and amino groups and of
the functional substituent. The NH bands are ob-
2
1
served at 3500 3000 cm ; a characteristic C=O
In the X-ray diffraction pattern of ammonium sul-
fate (Fig. 6, pattern 1), we identified its characteristic
reflections at 0.519, 0.433, 0.389, 0.314, 0.305,
1
band, at 1590 1650 cm ; and bands of CH, NH ,
2
1
and COO groups, in the range 1520 450 cm .
Weight, %
TG
DSC signal, W mg 1
DSC
T, C
Fig. 3. DSC and TG curves of Naturamin-WSP AAC; (T) temperature; the same for Fig. 7.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 80 No. 3 2007

3
54
PALECKIENE et al.
,
cm 1
Fig. 4. IR spectrum of Naturamin-WSP AAC: (T) transmis-
sion and ( ) wavenumber; the same for Fig. 8.
A, %
b
a
,
h
Fig. 5. Dynamic curve of water sorption A by AAC (1) un-
der ambient conditions and (2) in a desiccator over water.
(
) Time; the same for Figs. 9 and 10.
0
0
.299, 0.266, 0.252, 0.232, 0.217, 0.194, 0.177, and
.164 nm. The microcomplex consists of sulfates of
microelements and their crystal hydrates, and also of
boric acid; therefore, its diffraction pattern (Fig. 6,
pattern 2) contains reflections of magnesium, manga-
nese, copper, and zinc sulfates and of boric acid at
0
0
0
.754, 0.598, 0.534, 0.470, 0.447, 0.421, 0.378,
.341, 0.317, 0.299, 0.287, 0.267, 0.225, 0.220,
.209, 0.195, and 0.179 nm. The diffraction pattern
of ARVI microfertilizer (Fig. 6, pattern 3) contains
reflections of ammonium sulfate and the microcom-
plex. The diffraction patterns of ARVI microfertilizer
with addition of 1, 3, and 4% AAC (Fig. 6, patterns
4
6) exhibit reflections of ammonium sulfate, sul-
fates of microelements, and AAC. No new reflections
are observed, which indicates that the mixture is sta-
ble and no chemical reactions occur between the ferti-
lizer components.
2
, deg
Fig. 6. X-ray diffraction patterns of (1) ammonium sulfate,
(2) microcomplex, (3) ARVI microfertilizer, and (4 6) the
same + 1, 3, and 4% AAC, respectively.
The results of thermal analysis are given in Fig. 7.
The DSC curve of ammonium sulfate (Fig. 7a) dem-
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 80 No. 3 2007

PHYSICOCHEMICAL PROPERTIES OF A MICROELEMENT FERTILIZER
(a) (b)
Weight, % Weight, %
355
DSC signal, W mg 1
DSC signal, W mg 1
TG
DSC
Weight, %
(c)
DSC signal, W mg 1 Weight, %
DSC signal, W mg 1
(d)
Weight, %
(f)
DSC signal, W mg 1
Weight, %
(e)
DSC signal, W mg 1
T, C
T, C
Fig. 7. (1) TG and (2) DSC curves of (a) ammonium sulfate, (b) microcomplex, (c) ARVI microfertilizer, and (d f) the same + 1,
, and 4% AAC, respectively.
3
onstrates endothermic decomposition of the compound combination with weight loss (TG curve) from the
into gaseous ammonia and an acidic salt, NH HSO . initial components, ammonium sulfate and the micro-
4
4
The decomposition starts at about 300 and is complete complex. The DSC and TG curves of ARVI microfer-
at 455 C. The weight loss observed in the TG curve tilizer with 1, 3, and 4% AAC (Figs. 7d 7f) exhibit
is consistent with the elimination of ammonia.
the same peaks as in the curves for the separate com-
ponents. Some changes in the peak intensities and
positions (some of peaks overlap) are natural and in-
significant; thus, mixing of the components involves
no chemical reactions, and no new chemical com-
pounds are formed.
The DSC curve of the microcomplex (Fig. 7b) ex-
hibits an endothermic peak at 55.5 C indicative of the
dehydration of boric acid to metaboric acid HBO2
followed by further dehydration to boron oxide B O .
2
3
A pronounced endothermic effect at 116.9 C corre-
sponds to the onset of dehydration of magnesium,
manganese, copper, and zinc sulfate crystal hydrates.
The effect is complete at 283.1 C. The anhydrous salts
remain stable up to 600 C. A continuous weight loss
starting about 100 C corresponds to the dehydration.
The IR spectra of the initial substances, ARVI
microfertilizer, and ARVI microfertilizer with addi-
tions of AAC are shown in Fig. 8. In the IR spectrum
of ammonium sulfate (Fig. 8, curve 1) there are char-
+
acteristic absorption bands of the NH ion at 3000,
4
Thermal analysis of ARVI microfertilizer (Fig. 7c) 2000, and 1400 cm and of the SO2 ion at 1150
reveals a total endothermic effect (DSC curve) in 450 cm . Since the microcomplex contains a number
1
4
1
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 80 No. 3 2007

3
56
PALECKIENE et al.
of sulfates, in its IR spectrum there are strong absorp-
T
tion bands of SO2 at 1150 450 cm 1. Also present
4
1
are bands of boric acid at 1490 1428 cm and a
weak band at 2400 3000 cm 1 assignable to the
bridging BH group.
1
The IR spectrum of ARVI microfertilizer (Fig. 8,
spectrum 3) exhibits characteristic absorption bands
of both ammonium sulfate and the microcomplex.
The IR spectra of ARVI microfertilizer with AAC
additions are shown in Fig. 8, curves 4 6. The spec-
tra exhibit characteristic absorption bands of ammoni-
um sulfate, microcomplex, and AAC. In the frequency
range 3500 3000 cm 1 there are absorption bands of
1
the NH group, and a band at 1590 1650 cm corre-
2
1
2
sponds to the C=O bond. Bands at 1520 450 cm
are characteristic of the NH , CH , and COO groups.
2
2
All the absorption bands in spectra 4 6 are observed
at the same (or slightly shifted) positions as in the
spectra of the separate components (ammonium sul-
fate, microcomplex, AAC); therefore, we can con-
clude that no chemical reactions occur in ARVI mi-
crofertilizers.
3
To evaluate the sorption properties, we examined
the hygroscopicity of the separate components, ARVI
microfertilizers, and ARVI microfertilizers with AAC
additions under the same conditions as in the above-
described AAC tests. The dynamic sorption curves are
shown in Figs. 9 and 10.
Experiments on the water absorption under ambient
conditions (Fig. 9; 20 22 C, 25 37% humidity) show
that only ammonium sulfate (Fig. 9, curve 6) slightly
absorbs water, whereas the other components and fer-
tilizers with AAC (curve 2 5), especially the micro-
complex (curve 1), even lose moisture.
4
In a desiccator over water ( 21 C, 98% humidi-
ty), all the samples show a linear dependence of the
water absorption on time (Fig. 10). In 192 h, the sam-
ples start to dissolve, and on samples with AAC a
mold appears in 336 h. The lowest water absorption
is shown by the microcomplex (curve 1). All the other
substances (ammonium sulfate, ARVI microfertilizers,
ARVI microfertilizers with 1, 3, and 4% AAC) take
up considerably larger amount of water. The dynamic
sorption curves of the fertilizers with AAC resemble
that of ammonium sulfate (Fig. 10, curve 2), which
is the major component of the fertilizers.
5
6
Fig. 8. IR spectra of (1) ammonium sulfate, (2) microcom-
plex, (3) ARVI microfertilizer, and (4 6) the same + 1, 3,
and 4% AAC, respectively.
,
cm 1
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PHYSICOCHEMICAL PROPERTIES OF A MICROELEMENT FERTILIZER
357
(2) Studies of water absorption under various con-
ditions show that microelement fertilizers based on
ammonium sulfate and containing amino acid concen-
trate do not change their physical properties.
A,
%
, h
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1
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