Studies and analysis for the identification of the main principles of developing biodegradable coatings, using as raw materials PET wastes (December 2007).
Developing and experimenting the laboratory scale technology for yielding coating biodegradable materials, generated from aqueous co-polyesters dispersions, starting from PET wastes (September 2008).
Testing the laboratory scale technology for yielding biodegradable coating materials from water dispersible co-polyesters in order to yield slow release nutrients (September 2009).
Results dissemination (December 2009).
Developing and testing the pilot scale technology for yielding coating biodegradable materials, developing the detailed handbook for technology description and patent protection (November 2010).
OBJECTIVES ACHIEVED IN STEP I/2007
1. Evaluation of scientific approaches for achieving biodegradable coating materials from water dispersible co-polyesters produced by chemical recycling of PET wastes
Revue of scientic publications regarding the following aspects:
- procedures for obtaining water dispersable co-polyesters using as raw material PET wastes;
- possibilities of using such co-polyesters as coating materials for fertilizers;
- identification of analytical methods for characterization of biodegradable co-polyesters, water dispersable starting from PET wastes;
- technical and scientific evaluations regarding preparation of co-polyester aqueous dispersions;
- study regarding microorganisms involved in polyesters biodegradation.
2. Design of laboratory scale models
Designing laboratory scale experimental models regarding:
- synthesis routes for biodegradable water dispersible co-polyesters yielded from PET wastes;
- utilization of these co-polyesters as coating materials for fertilizers;
- preparing of aqueous co-polyesters dispersions;
- experimental model for testing the nitrogen release kinetics in greenhouse from coated granulated fertilizers. Establishing the connections between autotrofic microorganisms (bacteria and fungi) and the polyesters from soil.
OBJECTIVES ACHIEVED IN STEP II/2008
1. Developing the laboratory scale technology for yielding coating biodegradable materials, generated from aqueous co-polyesters dispersions, starting from PET wastes
1.1 Synthesis of biodegradable polyesters, water dispersible:
- There were obtained 12 experimental co-polyesters structures in order to select those chemical structures which are able to provide best properties of biodegradability and hydrophilicity and to establish the most suitable reaction parameters.
1.2 Preparation of aqueous co-polyester dispersions:
The representative co-polyesters prepared at laboratory scale were dispersed in water without involving any external surfactant, thus resulting 6 water dispersions.
2. Experimenting the laboratory scale technology for yielding coating biodegradable materials, generated from aqueous co-polyesters dispersions, starting from PET wastes
2.1 Physico-chemical and structural characterization of co-polyesters.
2.1.1 Determination of basic chemical and physical characteristics of yielded polyesters: melting range, content of acid and hydroxil groupes, medium molecular weight, relative viscosity determined at various polymer concentrations in solution, intrinsec viscosity and thermostability.
2.1.2 Complex structural characterization of co polyesters: 1H-RMN si 13C-RMN spectroscopy, FTIR spectroscopy and DSC (differential scanning chalorimetry) measurements.
2.1.3 Co-plyesters characterisation regarding their water affinity: measuremenrs of tensioactive properties, viscosity, turbidity, UV-VIS and FTIR-ATR spectroscopy, optic microscopy.
2.2 Characterization of water co-polyesters dispersions: stability, morphology and rheometry using conductometric, rheologic measurements and optic microscopy with image capture.
2.3 Laboratory scale testing of co-polyesters biodegradability. Testing the co-polyester effect upon the magnitude and structure of heterotrophic microorganisms communities in soil (toxicology).
OBJECTIVES ACHIEVED IN STEP III/2009
1. Improving the technology performance in order to obtain biodegradable coating materials resulted from PET wastes
- Synthesis of biodegradable water dispersible polyesters
Copolyesters of two classes of chemical structures were further investigated, in order to estabblish in detail the inffluence of other reaction parameters on the physico-chemical properties of the co-polyesters. The improvement of these properties was also an objective of this research step.
Three experimental co-polyesters structures were obtained. The co-polyesters have been caracterized as follows: basic chemical and physical characteristics as: melting range, content of acid and hydroxil groupes, medium molecular weight, relative viscosity determined at various polymer concentrations in solution, intrinsec viscosity were determined by physical and chemical methods, glass transition temperature and thermal stability were determined by DSC (differential scanning calorimetry) and TGA measurements; complex structural characteristics of co-polyesters were determined by instrumental methods (1
H-RMN spectroscopy and FTIR spectroscopy).
- Preparation of aqueous co-polyester dispersions
The three co-polyesters were transformed in three water dispersions. The characterisation of these dispersions consisted in dynamic viscosity measurements and determination of average particles size by means of dynamic light scattering (DLS) on a Nicomp Instrument.
2. Preparing slow release fertilizers
- Conditioning of fertilizer granules by coating with biodegradable co-polyesters film generated from water dispersions in order to yield slow release nutrients
Fertilizers conditioning was achieved on a rotational disk granulating machine, in a two steps discontinuous process, using N-P-K complex fertilizers and the three copolyester water dispersions previously prepared.
Three samples of coated fertilizers were obtained, which were sent to partner P5-ICPA for biodegradable co-polyester film evaluation and testing the nutrients release kinetics from fertilizer granules coated with co-polyester film in greenhouse.
3. Testing the evolution of fertilizer granules coated with biodegradable co-polyesters film in soil
- Biodegradable co-polyester film evaluation
- Testing in greenhouse the nitrogen release kinetics from fertilizer granules coated with co-polyester film. Selecting the involved microorganism in co-polyesters biodegradability
For the testing experiments the three coated ferilizers were used, together with a control sample (same fertilizer, uncoated). The experiments have been conducted in greenhouse, using as soil samples Eutric aluviosol, characterized by it's low content in nourishing elements mixed with the four fertilizing materials.
Small samples were collected every setled time period, which were analysed for: pH-reaction, total nitrogen content, phosphopus and kalium accessible content, nitrates content, in order to find out the release kinetics of the nourishing mineral elements from the fertilizers into the soil.
Each of the three coated fertilizers had it's own biodegrading dinamics, leading to different moments of mineral elements release.
OBJECTIVES ACHIEVED IN STEP IV/2009
1. Results dissemination by means of developing scientific communications
Four scientific communications were elaborated and presented in international scientific symposia, as follows:
1. 2-nd EUCHEMS CHEMISTRY CONGRESS, Torino, 16-th - 19-th of September 2008
"Synthesis of some biodegradable, water dispersible, film-forming co-polyesters from PET wastes and diols derived from biomass"
Colloque Franco - Roumain sur les Polymeres - SYNTHESE ET PROPRIETES DES POLYMERES; LES POLYMERES ET L'ENVIRONNEMENT - Alba Iulia, Roumanie, le 27 – 29 Aout 2009
"Co-polyester aqueous dispersions based on chemical recycled PET bottle wastes, for coating applications"
3. International Symposium "PRESENT ENVIRONMENT AND SUSTAINABLE DEVELOPMENT”, "Al. I. Cuza" University, Iasi, 16-th - 18-th of October 2009
"Chemical modifications in fertilized soil using mineral complex fertilizers coated with co polyester film obtained from PET wastes"
4. International Symposium "PRIORITIES OF CHEMISTRY FOR SUSTAINABLE DEVELOPMENT"-PRIOCHEM 5-th edition, Sinaia, Romania, 28-th - 30-th of October 2009
"Biodegradable polyesters from PET wastes and renewable materials"
2. CD-ROM editing
A presentation CD-ROM was edited, containing:
- The presentation of the project subject;
- The presentation of the project results;
- The four scientific communications presented above.
OBJECTIVES ACHIEVED IN STEP V/2010
1. Identification and assign of the patent rights
Subsequent to our research work, a patent application was submitted to OSIM,
"Aromatic-aliphatic, biodegradable, water dispersible co-polyester: synthesis procedure and water dispersion thereof"
National Research and Development Institute for Chemistry and Petrochemistry – ICECHIM- Bucharest, National Research and Development Institute for Soil Science, Agrochemistry and Environment Protection – ICPA – Bucharest.
Stela Iancu, Monica Duldner, Anca-Rovena Lacatusu, Emeric Bartha, Dan-Florin Anghel.
2. Developing the pilot scale technology for yielding aqueous co-polyesters dispersions
- Performance improvement of the pilot procedure for synthesis of biodegradable and water dispersible co-polyesters and for producing their corresponding water dispersions
Subsequent to the results achieved, one co-polyester structure has been selected, which showed the most appropriate characteristics, according to our goals: basic chemical and physical characteristics of the co-polyester, including hydrophylicity and bio-degradability, basic chemical and physical characteristics of the aqueous dispersion, appropriate behavior of the dispersion in the fertilizer encapsulation process, controlled release of the nutrients in soil from the encapsulated fertilizers.
Experiments have been done, in the pilot plant, in order to reproduce the selected co-polyester and optimize the reaction parameters of the synthesis and preparation of dispersion processes. The final parameters have been established and 4 Kg of co-polyester, corresponding to about 12 kg of dispersion and about 160 Kg of encapsulated fertilizers have been produced.
3. Experimenting the pilot scale technology for yielding aqueous co-polyesters dispersions
- Determination of basic chemical and physical characteristics of the pilot yielded polyesters and dispersions
- Checking for the reproducibility of the pilot co-polyesters characteristics
- Checking for the reproducibility of the pilot co-polyesters chemical structure
- Rheologic characterization of aqueous co-polyester dispersions, determination of particle size distribution and stability
Basic chemical and physical characteristics of the co-polyester and its aqueous dispersion have been determined (for the co-polyester: melting range, acid number, hydroxyl number, intrinsic viscosity; for the dispersion: dynamic viscosity, particle size). We found that these characteristics had the same values as the targeted values obtained in our previous experiments. The thermal characteristic (thermal stability and glass transition temperature) were also appropriate to our goals (glass transition temperature was found to be 35°C). The chemical structure of the co-polyesters was reconfirmed by 1
H-NMR and FTIR spectroscopy.
The resulted co-polyester was also analyzed regarding its hydrophilic character. We found that the surface tension of the co-polyester in aqueous solutions was lower than that of surfactants, the co-polyester presenting more like an polyelectrolyte character As a conclusion. the results recommend the co-polyester to be used as biodegradable, water-dispersible, and film forming agent. The water dispersion was also characterized from rheological point of view (it was found it displays a viscoelastic Maxwell fluid behaviour), and regarding the particle size. Conductometric measurements were performed in order to evaluate the stability of co-polyesteric water dispersion.
4. Testing the pilot scale technology for yielding biodegradable co-polyester coating materials in order to yield slow release nutrients
- Checking for the reproductibility of the slow-release nutrients preparation
- Checking for the reproductibility of the co-polyester film biogeradation
- Checking for the reproductibility of the characteristics of biodegradability for the pilot products
For the preparation of the encapsulate fertilizers, a plant was accomplished, simulating a modified fluidized bed, frequently used in "Wurster" encapsulation processes
. The process parameters have been established in order to obtain coated fertilizers which do not stick or agglomerate at normal temperature. Two samples of coated fertilizers have been obtained, using a complex NPK 15,15,15 fertilizer provided by SC MONDISTAR SRL and a complex NPK 15,15,15 +S +Zn - LINZER STAR, provided by S.C. LINZER AGRO TRADE Romania S.R.L.
A film sample, prepared from the experimental dispersion, was tested for biodegradability. There was found that the film was almost entirely biodegraded in 75 days from the inoculation, in presence of the heterotrophic microorganisms communities in soil. Both samples of coated fertilizers were tested in green house, for nutrient release kinetic measurements. The sample provided by S.C. LINZER AGRO TRADE Romania S.R.L. was tested on a corn hybrid: PR39D81 (group FAO 200). Data were processed by statistic ANOVA method (using Student and Tukey tests). The nutrient substances release rate was found to be smaller for the encapsulated fertilizer than for the control sample. In the same time, the presence of the co-polyester did not determine any toxic effects on the microorganisms community in soil.
5. Developing the detailed handbook for technology description
The conclusion was that our technology leads to the manufacture of a product which suits the application aimed domain, therefore the Handbook for technology description was elaborated, named "Technology for manufacture of biodegradable coating materials from water dispersible co-polyesters obtained by chemical recycling of PET wastes".