versión On-line ISSN 0717-9707
J. Chil. Chem. Soc. v.54 n.4 Concepción dic. 2009
J. Chil. Chem. Soc., 54, Nº 4 (2009), págs. 448-453.
CHITOSAN-COPPER PAINT TYPES AS ANTIFOULING
MARCIA HEUSERa, CLAUDIA RIVERAa,CHRISTIAN NUÑEZa AND GALO CÁRDENASa*,
a Advanced Materials Laboratory, Polymers Department, Faculty of Chemical Sciences, Universidad de Concepción.CIPA. Concepción, Chile. e-mail: firstname.lastname@example.org
A prototype of antifouling paints was prepared with a QS-Cu (I)-Fe (II) complex as a possible replacement for traditional antifouling paints, which contain a large concentration of copper, fnding them in an order of 10 - 30 % depending on the brand, and if it is water or solvent based. A Qs-Cu complex was prepared, with a solution at 3% with acetic acid, and then Fe2O3 was added to the solution. FT IR analysis was carried out, as well as analysis of the TGA at the Qs and the complex with Qs-Cu, and with the solution, three different paints were prepared. Those that varied volumen of diethylene glycol added to them. The analysis of the paints was carried out, once the paint was pervaded in a network of polyamide, through SEM with EDX and TEM, which was purchased with the commercial paints, water based and solvent based. One of the objectives is to be able to compare the coverage of the network with the commercial paint, and that of the complex QS-Cu. The results showed that the best paint obtained was paint #2, found to be similar to that pervaded with water based paint.
To decrease the "fouling" effect (the phenomenon of accumulation of an elevated biodiversity of opportunist organisms) on the nets used for the cultivation of trout and salmon, a series of antifouling paints have been formulated (1-7). The principal is based on a thin layer of antifouling paint, whose composition is a biocide. On the submerged surface, a thin cap of a solution, this is toxic for the early phases of the organisms that make up the fouling, forms by dissolving (8). The composition, abundance and seasonality of the fouling depend on geographic factors such as water temperature, salinity, lighting, tides, and turbidity, among other things (9). There are organisms that colonize marine installations in their frst life stages or larval stages, where they move freely by the water column in search of a substrate to settle down on. Then, these communities begin to develop, increasing their weight and size, which causes the following consequences: Increase of the solid area on the net, which decreases the fow of water thorough it by 30 to 40% (2, 10), which therefore creates an increase in the resistance to currents and a change in the conditions within the cage, reducing the O2(g) levels and increasing the ammonium levels, produced by the decomposition of organic material (11).
Antifouling paints are basically made up of: a binding body or matrix, active compound, auxiliary compounds, solvent. These products are only formulated with a cuprous oxide such as biocide, its leaching is in smaller quantities, and therefore, it does not affect the salmon or the area surrounding the cages (12). The matrix or the binding body of the antifoulings determines the velocity with which the biocide particles will be released from the active component. The velocity of leaching or detachment of the toxic agent is a critical factor that infuences the effciency of the coating, it should suffciently high to provide protection, but not excessively high, which would reduce the duration of the coating, and elevate the releasing in the marine environment (13).
One of the big problems of salmon farming is the growth of aquatic fungi, which makes up one of the most frequent mycosis in fresh water fsh. Three orders (Saprolegniales, Leptomitales y Feronosporales) of the class Oomycetes includes species that can infect the fsh, those belonging to the Saprolegniaceae family being the most pathogens (14). The species of the genus Saprolegnia have an accepted mycelium, very branched, with a cotton-like look under water. Its reproductive structures are separated from the somatic hyphas by septum and the asexual reproduction is carried out by bifagellate zoospores produced by vegetative hyphas, which are mobile, and therefore facilitates their dispersion (15).
Chitosan was purchased from Quitoquimica Ltda. Its degree of deacetylation was 80% and its Mv was 103.900 g/mol. (16). Cuprous oxide was purchased from the Sigma- Aldrich Chemical Company. Acetic acid came from Fisher Scientifc Commercial. Iron trioxide was purchased from Sigma-Aldrich Chemical Company, dietilenglicol Merck-Schuchardt and ethanol 95% from Diprolab.
Preparation of the (complex Qs-Cu)
For the preparation of the complex 1:3 Qs-Cu, it was left in ethanol for twelve hours with constant stirring. It was then fltered and dried at 40°C (17).
Preparation of the Composite (Qs-Cu Paints)
The complex Qs-Cu (I) was weighed, and Fe2O3 was added to avoid the oxidation of copper (I) to copper (II), acetic acid was added until it reached a capacity of 100 ml in constant stirring. From this solution, three different paints were prepared; paint #1, paint #2 and paint #3, which varied in volume (2, 3, 4ml) of added Diethylene glycol, whose mix is agitated for 2 hours.
Spectrophotometry FT IR Nicolet Magna Model 550 connected to a computer with OMNIC software for data processing. A pill of KBr at 2% is prepared from each sample.
Perkin was used - Elmer model TGA - 7 with a temperature control microprocessor and a program of data for thermo analysis. They weigh between 3-5 mg and create a warming program of 10ºC /min from 25-550ºC in an atmosphere of nitrogen (16).
The microstructure, morphology and the thickness of the flm were imaged using a JSM6380LV-JEOL Scanning Electron Microscope; front and cross section micrographs were obtained from each sample, the micrographs were taken 5000X of magnifcation for the front side and between 1000X and 3000X of magnifcation for the cross section (18).
Electronic microscope of a JEOL 1200 EX II transmission of a 4 Å of resolution, equipped with an EDX Model Norell, which also permits analysis by electron diffraction (18).
RESULTS AND DISCUSSION
From fig 1.a in chitosan, it is possible to observe the existence of the complex formation between the copper ion with the NH2 (C-2) group so as with the group OH (C-6). (18)
We can observe that the band according to NH2 free group of chitosan change its absorbance when complex form with copper (compare the figures 1.b 1.c). Table 1 exihibit the ftir adsorptions. The band at 355 related to δHO-Cu and δN-Cu at 443 in table 2 are the most important to observe the reaction of copper with chitosan.
There is no great variations are observed in the thermogravimetric analysis carried out on Paint 1 BPM and Paint 2 BPM, this analysis was not carried out for 3 BPM.
Table 5 identifes the elements that constitute the solvent paint, water paint and Qs-Cu (I) and in table 5 percentage points the atomic for copper and iron in samples across SEM, for the spectrum a greater percentage of atomic copper and iron is presented.
With the SEM analysis, the form in which the net absorbed the paint could be observed. It could be said that among the commercial paints, the water based paint with a measurement of 7.75 µm in the fber presents the best impregnation, as this is impregnated on the fber in a homogeneous way, unlike the solvent based paint with a measurement of 4.19 µm in the fber (see fig. 2), which begins to chip once dried. The three paints carried out with the Qs-Cu complex of BPM were absorbed by the fber, observed through the micrographs a greater penetration in the fber by paints #2 and #3. In paint # 1 an impregnation in the form of piles on the fber was observed, therefore, in this case, how much paint was absorbed by the fber was not analyzed. In the case of paint #2, it presented an average penetration in the fber of 8.25 µm, and in the case of paint #3, an average penetration in the fber of 2.41 µm. Therefore, paint #2 has the greatest penetration power, followed by the water based paint.
Table 5 shows the percentage of atomic elements Cu and Fe, in samples obtained through EDX.
With the EDX analysis, it can be said that no paint, neither commercial nor that prepared with the Qs-Cu complex, homogeneously impregnated the net, which could be explained by the fact that no paint is completely homogenous.
The analysis by TEM was carried out at Cu2O (Fig. 3.a) and at Fe2O3, (Fig. 3.b), both electron diffraction and transmission micrograph, to be able to determine the size and shape of the particles and therefore be able to see how the compounds are principally found in the Qs-Cu paints. It is observed that the Fe2O3 particles have a smaller size compared to the Cu2O.
The analysis of the average size of the particles ends up being of 0.02 µm.
Electron micrography was carried out on paints #1, #2 and #3 of the Qs-Cu complex of BPM to obtain particle size and its morphology.
The images show the different shapes and sizes of the particles. Micrographies were obtained, in order to prove if the size and morphology of the particles are homogenous.
The analyses of the electron diffraction either in Cu2O or Fe2O3 reveals a good proximity of the experimental compared with tabulated data for crystallographic planes. Since is a paint the crystallinity is not quite relevant.
After the analysis of the data it is possible to summarize the planes from the electron diffraction data (see table 7).
The analysis of the oxides was carried out in a liquid phase; the liquid phase was carried out with acetic acid. The particle size of paint #1 of BPM is of 15.31 µm; comparing these particles with the Cu2O and Fe2O3 particles, it could not be known with certainty of which particles it is principally made up of, as the particle size of the oxides is not found within a range, rather as a unique value. Electron diffraction was carried out, which indicated that the paint is composed of oxide particles of iron, as deduced by the values of d hkl practical and theoretical(18).
Particle size of the BPM paints is a factor that infuences the penetration of the paint in the fber, as a smaller size of particles in the paint would beneft in the sense that the paint would penetrate the fber with greater ease, which is better, as it facilitates a better impregnation of the paint in the fber. Perhaps for this reason, the water based commercial paint has good penetration in the fber .
The initial decomposition temperature of the complexes Qs-Cu (I) BPM and Qs-Cu (I) APM, occur at 233 and 248 ° C, with a remaining mass of 92% and 94 % respectively at that temperature. In contrast, paint #1 BPM and 2 BPM both have an initial decomposition temperature of 75 °C, with a remaining mass at this temperature of 98 %. These differences are due to the paints low molecular weight containing diethylenglycol, and by being laminating made the polymer lower its point of fusion.
According to the FT-IR range carried out at the Qs-Cu (I) complex and at the Qs, it could be proven that there is formation of complexes between the groups NH2 and OH of the Qs with the Cu (I).
In scanning electronic microscopy (SEM), it was observed that the paint that best impregnated the net was paint #2 of BPM, as, unlike the other paints, it is absorbed by the fber and not covered by layers. According to the size of paint #3, it should penetrate more, but it is observed in Table 2 that it penetrates less than 1/3 than paint #2. This is because they have a smaller particle size.
In transmission electronic microscopy (TEM), through electron diffraction, it was concluded that the paints of low molecular weight are mainly made up of iron, which would indicate that there would be a better impregnation of paint in the fber, as the particles of iron oxide are of a smaller size than those of copper, which facilitates the paint impregnating the net with greater ease through impregnated physical adsorption of the Fe2O3 that does not form part of the complex.
According to the analysis carried out and the obtained results in this report, it is concluded that the best antifouling paint is paint #2 of BPM.
The authors would like to thank the fnancial support of Fondef DO 4I-1286 Project and the scholarship granted to M. Heuser.
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(Received: April 7, 2009 - Accepted: August 17, 2009).