El uso actual y potencial de la nanotecnologia en el sector

agroalimentario

Caue RibeiroPesquisador

Coordenador da Rede de Pesquisa em Nanotecnologia Aplicada ao Agronegócio,

EmbrapaTercer Seminario Regional Agricultura y Cambio Climatico:Nuevas tecnologías en la mitigación y adaptación27 y 28 de septiembre 2012

Nanociência, nanotecnologia…

Credits: Prof. Dr. Henrique Toma (USP, Brazil)

Superfícies e Catálise HeterogêneaProdutividade de reações químicas: uma

área nanotecnológica há um século! “catalytic materials [heterogeneous catalysis] have been

nanostructured for at least a century, and this industry – US$ 100 bilion – is (…) estimate of a future trillion dolar nanotechnology economy (Prof. Dr. David J. Eaglesham, in Letter from the President, MRS Bulletin 2005, 30, 260 – 261)

Prêmio Nobel de Química 2007: Prof. Dr. Gerhard Ertl "(...) Chemical reactions on catalytic surfaces play a vital role in many industrial operations, such as the production of artificial fertilizers [processo Haber-Bosch] (...)" (Nobel Prize Press Release)

Processo Haber (1910)

N2 + 3 H2 → 2 NH3

- Produção de fertilizantes e explosivos....

Processo catalisado por ferro metálico

N2

H2

NH3

Exemplo de processo químico catalisado por superfícies e esquema do processo Haber.Fonte http://www.spaceflight.esa.int/impress/text/education/Catalysis/index.html

Superfícies e Catálise Heterogênea

Coordenação: Embrapa Instrumentação158 pesquisadores / 53 Instituições

Linhas de pesquisa:•Sensores e Biossensores•Filmes finos comestíveis e embalagens ativas•Bionanocompósitos•Novos usos de nanomateriais sintéticos na agricultura•Avaliação de Impactos em Nanotecnologia•Transferência para a Sociedade em Nanotecnologia

http://www.redeagronano.cnptia.embrapa.br/

Como a Nanotecnologia chega ao Consumidor Final?

• Três níveis de impacto no consumidor final:– Direto: alimentos com nanotecnologia

• Nanoaditivos e filmes finos comestíveis

– Indireto, com possível contato ou migração: alimentos produzidos, processados ou conservados com auxílio de nanotecnologias

• Insumos agrícolas, descontaminação de água, embalagens ativas

– Indireto, com mínimo contato ou possibilidade de migração : alimentos monitorados e avaliados com auxílio de nanotecnologia

• Sensores de qualidade

Nano’s em alimentos

Credits: Embrapa Instrumentação Agropecuária(Dr. Odílio B. G. Assis)

Revestimentos protetores comestíveis

Quitosana

Zeínas

CMC

Nano’s em alimentos

Nanocápsulas

cápsula (50 – 250 nm)

polímero

Espaçovazio

Nanocápsulas para liberação controlada / lenta e nanoemulsões

Emulsão bifásica convencional (maionese)(em http://tecalim.vilabol.uol.com.br)

eXPRESS Polymer Letters Vol.4, No.8 (2010) 509–515

Nanocápsulas de quitosana

Embalagens Nanocompósitas

Oxygen permeability of PLA, PHB and PET and of their nanocomposites

Nanocargas: Nanocelulose

Source: Teixeira et al, Cellulose, 2010

Embalagens inteligentes

Migração para alimentos?

LDPE: n = 2.6 × 10-7 kg of nanosilver (0.26 mg) after 1 year at 25oCPET: n = 2.2 × 10-10 kg (0.22 μg) of nanosilver after 1 year at 25oC

Rastreabilidade: Biosensores

14

http://www.cnpat.embrapa.br/cnpat/cd/jss/acervo/Dc_117.pdf

Rastreabilidade:Sensores não-seletivos

pro

pri

edad

e

variável

Sensor 1

Sensor 2Sensor 3

Resultado

Sensores não-seletivos

Identificação de sucos de fruta usando a Língua Eletrônica

• Plantio direto na palha• Recuperação de áreas degradadas• Integração Lavoura – pecuária – floresta• Plantio de florestas comerciais• Fixação biológica de nitrogênio• Tratamento de resíduos animais

http://www.agricultura.gov.br/abc/

Estratégias para mitigação deemissões de N2O

Como a nanotecnologia pode colaborar com essas estratégias?

Conceitos

Liberação comumLiberação lenta

Liberação controlada

tempo

Qu

anti

dad

e A

cum

ula

da

Faixa deinteresse

Estruturas Reticuladas (Hidrogéis)

seco

hidratado

http://www.estadao.com.br/noticias/suplementos,aplicacoes-em-escala-atomica-na-agricultura,640974,0.htm

Values of KF and n were calculated from the inter-cept and slope of the plot of ln qe q versus ln Ce q .The fitted lines of the data modeled using the

Freundlich and Langmuir isotherms for the adsorp-tion of fertilizers from hydrogels composed by 6.0%AAm and 1.0% MC are shown in Figure 5. The ini-tial concentration of the fertilizers varied between 50and 2000 mg L 1 . Based on R2 values, the Freundlichmodel fits the both fertil izers better than the Lang-muir model. It was possible to determine the KF andn Freundlich parameters. The KF parameters calcu-

lated were 1.271 and 1.176 L g 1 for (NH 4 )2SO4 andKH 2PO4 fertilizers, respectively. In addition, the val-ues of n parameter for (NH 4 )2SO4 and KH 2PO4 fertil -izers were 1.727 and 1.641.

CONCLUSIONS

Because it is a simple technique, highly reproduci-ble, low cost, and allows a direct detection withoutprevious treatment of the analyte, the conductivitytechnique was extremely efficient in this study. It

Figure 4 Profiles of ammonium sulfate (NH 4 )2SO4 release from hydrogels constituted by PAAm and MC as a function oftime in different conditions: (a) [AAm] ¼ 9.0 in wt % with 0; 0.5; and 1.0 MC in wt %, and (b) [MC] ¼ 1.0 in wt % with6.0; 9.0; and 12.0 AAm in wt %. Error bars represent standard deviations for the three measurements (mean 6 SD, n ¼ 3).

TABLE IVCumulative Release and Amount of (NH 4 )2SO 4 Ferti l izer

Released for Dif ferent Hydrogels

(AAm-MC)hydrogel

Cumulativerelease (%)

Amount of fertilizerreleased (mg (NH 4 )2SO4 )/ g

hydrogel)

(6.0–1.0) 85.3 6 2.2 49.5 6 4.8(9.0–0) 106.8 6 2.7 14.1 6 0.2(9.0–0.5) 97.0 6 3.4 19.6 6 1.5(9.0–1.0) 96.7 6 2.9 35.5 6 6.3(12.0–1.0) 99.4 6 0.8 15.3 6 0.8

TABLE II ICumulative Release and Amount of KH 2PO 4 Ferti l izer

Released for Di f ferent Hydrogels

(AAm-MC)hydrogel

Cumulativerelease (%)

Amount of fertilizerreleased (mg KH 2PO4 )/ g

hydrogel)

(6.0–1.0) 44.3 6 1.2 54.9 6 7.9(9.0–0) 97.5 6 1.4 30.8 6 1.0(9.0–0.5) 80.6 6 4.1 35.4 6 2.5(9.0–1.0) 50.4 6 0.8 41.0 6 1.0(12.0–1.0) 85.5 6 2.7 22.4 6 0.7

2296 BORTOLIN ET AL.

Journal of Applied Polymer ScienceDOI 10.1002/ app

Values of KF and n were calculated from the inter-cept and slope of the plot of ln qe q versus ln Ce q .The fitted lines of the data modeled using the

Freundlich and Langmuir isotherms for the adsorp-tion of fertilizers from hydrogels composed by 6.0%AAm and 1.0% MC are shown in Figure 5. The ini-tial concentration of the fertilizers varied between 50and 2000 mg L 1 . Based on R2 values, the Freundlichmodel fits the both fertil izers better than the Lang-muir model. It was possible to determine the KF andn Freundlich parameters. The KF parameters calcu-

lated were 1.271 and 1.176 L g 1 for (NH 4 )2SO4 andKH 2PO4 fertilizers, respectively. In addition, the val-ues of n parameter for (NH 4 )2SO4 and KH 2PO4 fertil -izers were 1.727 and 1.641.

CONCLUSIONS

Because it is a simple technique, highly reproduci-ble, low cost, and allows a direct detection withoutprevious treatment of the analyte, the conductivitytechnique was extremely efficient in this study. It

Figure 4 Profiles of ammonium sulfate (NH 4 )2SO4 release from hydrogels constituted by PAAm and MC as a function oftime in different conditions: (a) [AAm] ¼ 9.0 in wt % with 0; 0.5; and 1.0 MC in wt %, and (b) [MC] ¼ 1.0 in wt % with6.0; 9.0; and 12.0 AAm in wt %. Error bars represent standard deviations for the three measurements (mean 6 SD, n ¼ 3).

TABLE IVCumulative Release and Amount of (NH 4 )2SO 4 Ferti l izer

Released for Dif ferent Hydrogels

(AAm-MC)hydrogel

Cumulativerelease (%)

Amount of fertilizerreleased (mg (NH 4 )2SO4 )/ g

hydrogel)

(6.0–1.0) 85.3 6 2.2 49.5 6 4.8(9.0–0) 106.8 6 2.7 14.1 6 0.2(9.0–0.5) 97.0 6 3.4 19.6 6 1.5(9.0–1.0) 96.7 6 2.9 35.5 6 6.3(12.0–1.0) 99.4 6 0.8 15.3 6 0.8

TABLE II ICumulative Release and Amount of KH 2PO 4 Ferti l izer

Released for Dif ferent Hydrogels

(AAm-MC)hydrogel

Cumulativerelease (%)

Amount of fertilizerreleased (mg KH 2PO4 )/ g

hydrogel)

(6.0–1.0) 44.3 6 1.2 54.9 6 7.9(9.0–0) 97.5 6 1.4 30.8 6 1.0(9.0–0.5) 80.6 6 4.1 35.4 6 2.5(9.0–1.0) 50.4 6 0.8 41.0 6 1.0(12.0–1.0) 85.5 6 2.7 22.4 6 0.7

2296 BORTOLIN ET AL.

Journal of Applied Polymer ScienceDOI 10.1002/ app

Fonte: Bernardi et al, 2010

0

2

4

6

8

10

0 2 4 6 8 10 12 14 16 18 20 22

Period (days)

N v

olat

ilize

d (m

g pe

r po

t)

Urea

Urea_inc

Urea_NBT

Urea_Zeo

NH4NO3

NH4SO4

Control

Ureia (comum) por cobertura

Ureia + zeolita por cobertura

Ureia incorporada no solo

UréiaZeólita

Uréia + Zeólita 5%

Zeólitas para redução da Volatilização de Nitrogênio

Nanocompósitos fertilizantes

urea

Test.

Form. 1

composites is noteworthy, with negligible di erences observedbetween them. This suggests that the mechanical behavior isdominated by the intercalated fraction of the material, whichdeforms continuously when solicited. This is an interestingbehavior for thepractical useof thosematerials, because fragilegranules are more prone to produce dust during application,which may be avoided or minimized by the nanocompositematerials.Figure 8 shows the urea release for the three produced

nanocompositescompared to urearelease. Theureadissolutionoccurred in <1h, dueto thesolution saturation around theureagranule. We performed a reference test, by mixing (withoutextrusion) a composition of 1:1 montmorillonite/ urea, that is,where theclay wasnot properly exfoliated (not shown here). Inthis case, the liberation test in the same conditions of theextrudegranulesdid not shown any in uenceof theclay in urearetention, with almost thesamepro leof pureureadissolution,asshown in Figure8. Thispro leprobably isrelated to the factthat any interaction of montmorillonite and urea would occurin longer times, because the compound would need to adsorbin montmorillonite platelets after its dissolution. Then, in thisvery aggressive test condition (immersion in water), anydi erence could be observed. In fact, this also shows theimportance of exfoliation to the controlled release.

However, by comparing the nanocomposites, one can notethat all of the formulations retarded urea release for up to 120h. It wasvery important to notethat thisdissolution experimentwas very aggressive, because a complete immersion of theproduced materials in water is done. Even in this aggressivecondition, the release iscomparable to other controlled releasesystems with very di erent action principles, as observed byTomaszewska and Jarosiewicz1 4 (for some polymeric coatingsapplied in urea granules) or in PMMA hydrogels, as reportedby Bortolin et al.,2 2 denoting that those valuesobtained for thenanocompositesarepromising. In conventional application, thematerialswould beexposed to lowwater contents, and onecanexpect a better retention e ect by the nanocomposites.A particular aspect is the di erent kinetic behavior observed

for each system. Therewasnot aclear correlation between thetotal Mt in the nanocomposite and the total urea released. Infact, the 1:1 formulation caused higher urea retention, but onlysmall di erenceswere observed using the1:2 and 1:4mixtures.This may mean that the e ect of the Mt clay in minorquantities is less considerable, but, in any case, it is veryimportant to note that even those nanocomposites showedslower release when compared to pure urea.To separate possible solution equilibrium e ects, a second

experiment to measure urea release was performed, comparingpure urea and formulation 1:1 when protected by a dialysismembrane. In this case, one can consider that the osmoticpressure between the inner and outer parts of the membrane

Figure 6. Scheme of the proposed path for urea intercalation in theextrusion process.

Figure 7. Stress−strain curves for the pure urea and for the Mt/Ur composites.

Figure 8. Release rate of urea asa function of time for pure ureaandeach of the composites at pH 7 and room temperature.

Journal of Agricultural and Food Chemistry Article

dx.doi.org/10.1021/jf3001229 | J. Agric. Food Chem. 2012, 60, 5267−52725271

shown in Table 2. The ratios of Si, Al, C, N, and O content inatomic percent in the individual points marked accordingFigure 5 are summarized in Table 2. The regions labeled “1” inthe SEM images correspond to urea crystals redispersed,because theelementsdetected are predominantly N, C, and O,that is, urea constituents. On the other hand, the regionslabeled “2” correspond to urea-intercalated Mt, becausesigni cant amountsof Si and Al (clay constituents) and smallerN amounts were detected.

By the above results, one may propose a path of the ureaintercalation in the extrusion process, as shown in Figure 6. Atthe rst urea loadings, the solubilized material intercalates inclay platelets, properly forming the composite. However, thesubsequent additions do not interfere with the Mt separation,but will crystallize independently, forming some small ureacrystals, which can grow by addingmore urea into the process.A comparative analysis of the mechanical resistance of the

granuleswasperformed by diametral compression, because thisproperty is very important for the practical application as afertilizer material. As observed in Figure 7, the behavior of aurea granule is similar to that of a fragile material, with poorplasticity and fracturing at low pressure. On theother hand, allof the nanocomposites were very deformable, without ruptureeven until the maximum deformation supported by theequipment. It is noticeable that this behavior can not beassumed to besolely due to theMt structure, because thesameanalysis in the pure Mt extruded revealed a low mechanicalresistance. However, the similarity among the three nano-

Figure 4. Thermogravimetric curve (a) and derivate thermogravimetric curve (b) of Mt, pureurea, and thenanocompositesMt/ Ur 1:1, Mt/Ur 1:2,and Mt/Ur 1:4.

Figure 5. SEM images of (a) Mt and the nanocomposites (b) Mt/Ur1:1, (c) Mt/Ur 1:2, and (d) Mt/Ur 1:4. Magni cation of 500 (left)and 20000 (right).

Table 2. Ratios of C, N, O, Al, and Si in the Composites(Marked by Numbers in Figure 5) Measured by EDX inAtomic Percent

C N O Al Si

Mt/ Ur 1:1P1 5.2 21.8 14.0 3.9 5.1P2 1.8 35.1 16.5 33.9

Mt/ Ur 1:2P1 3.7 17.7 16.2 7.0 11.2P2 2.8 23.6a 12.8 28.5

Mt/ Ur 1:4P1 4.7 21.3 14.3 4.0 6.5P2 0.2 2.4 25.5 12.6 27.3

aThe value corresponds to the sum of O and N signals.

Table 3. Values of Mechanical Parameters

σa (MPa) Eb

urea 2.083 ± 0.4507 3.32 ± 1.45extruded Mt 12.32 ± 13.71 6.00 ± 1.90Mt/ Ur 1:1 >35.13 ± 3.627 0.99 ± 0.64Mt/ Ur 1:2 >31.24 ± 3.516 1.06 ± 0.51Mt/ Ur 1:4 >33.20 ± 3.495 2.01 ± 0.90

aσ = stress. bE = elasticity modulus.

Journal of Agricultural and Food Chemistry Article

dx.doi.org/10.1021/jf3001229 | J. Agric. Food Chem. 2012, 60, 5267−52725270

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