The importance of validation methods for emerging technologies: the case of alternatives for single-use plastics

Alejandro Quintero Vélez y Fabián Steven Mosquera Rodríguez, students from the Chemical Engineering Program and authors if the research. Credit: students courtesy. 

The high concentration of waste in water sources, especially single-use plastics such as bags, packaging and bottles, has become a threat to the environment worldwide. Faced with this situation, new technologies have been developed that seek to offer sustainable alternatives. Seeking to provide a better basis for the possible benefits of adopting these technologies, a research study proposed an analysis method for one of these alternatives. 

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From anecdote to research 

Before embarking on his degree project, Fabian Steven Mosquera Rodríguez, a student from the Chemical Engineering program at the Universidad del Valle, decided to conduct a small experiment, not knowing that the results would lead him to consider the need to focus his academic efforts in a similar line. The idea was to test the degradability of a small plastic jar he had come across at lunch, which he claimed to be compostable within six months, a quality that seemed to him to be quite adequate to the world's current needs.  

But the experiment did not give the expected results: the glass was still intact, four months later. 

Although Fabián's desire was to produce a biocomposite that would be biodegradable, the proposal took a turn. Thanks to the direction of the professor and researcher of the School of Chemical Engineering, Howard Ramírez Malule, and the participation of the researcher and professor of the School of Materials Engineering, José Herminsul Mina Hernández, and the professor and researcher of the Universidad Tecnológica del Chocó, Estivinson Córdova Urrutia, and the collaboration of the LASA (Water Laboratory) of the Universidad del Valle, the research of Fabián Steven Mosquera Rodríguez, together with another student from the School of Chemical Engineering, Alejandro Quintero Vélez, focused on a degradability study that sought to determine under what conditions and how long it would take for a biocomposite with innovative characteristics to complete its degradation cycle.  

The results of this research were published in the journal Polymers, providing a window of analysis for the growing field of biocomposites and their application in society. 

An opportunity to evaluate available biocomposites 

After exposing his research interest with the other researchers, it was determined to evaluate the degradability of a biocomposite made from a binary mixture of thermoplastic banana starch (TPS) and polycaprolactone (PCL) reinforced with fique fibers (F), a bet developed by the researcher Estivinson Córdoba Urrutia for his thesis for the PhD in Bioengineering offered by the Universidad del Valle in association with the Universidad Autónoma de Occidente. For this evaluation, students Mosquera Rodríguez and Quintero Vélez developed an experimental design that subjected the biomaterial to three conditions: soil and compost (at 5, 10 and 20 cm depth) and an additional one in an aqueous environment (at 20 cm depth); the latter was determined considering that, on many occasions, these wastes end up in water sources. 

biocomposite made from a binary mixture of thermoplastic banana starch (TPS) and polycaprolactone (PCL) reinforced with fique fibers (F), used to carry on the degradability tests. Credit: students courtesy.

The evaluation was carried out over a period of 90 days, during which the condition of the samples was monitored every 30 days by means of infrared spectroscopy (IR), which allowed them to identify the modifications suffered by the functional groups of the compounds that make up the biomaterial.  

"We saw that, with thermoplastic banana starch reinforced with fique fibers, that compound has a lot of hydroxyl (OH) bonds. When we used the IR technique, at the beginning they had a fairly high intensity, but after a month that intensity was reduced, and that continued for the next two months. That was an indication that the amount of those bonds was being reduced. That is to say: they were being consumed in some way because probably some type of microorganism was degrading them", explains Fabián Steven Mosquera Rodríguez, and adds that at the same time they were carrying out a physical analysis of the samples, seeking to determine the loss of mass with respect to time and thus confirm the degradation process.  

Similarly, scanning electron microscopy (SEM) was used for the analysis process, which, like IR, allowed them to see in greater detail the degradation process inside the biomaterial, along with tests that sought to evaluate the mechanical properties of the biomaterial, to estimate its resistance capacity - how much it could elongate before it fractured - before being subjected to the experiment and after it was subjected to the experiment. This test also helped to estimate with certainty the existence of degradation in the biocomposite. 

Biocomposite analized under soil conditions. Credit: students courtesy.

Results: an endorsement of the joint effort 

After 90 days, the samples showed signs of degradation. The best results were obtained in the compost condition at a depth of 20 cm (there was a mass loss of 34 ± 4% and a decrease in tensile strength of 77.3%: evidence that the material evaluated lost mechanical properties). In the soil condition, the loss was 26%. On the other hand, the evaluation in aqueous medium showed the lowest results, with only 20% loss of mass compared to the initial condition.  

Although the degradation of this biocomposite was something they foresaw from the beginning, for the student Mosquera Rodríguez the results obtained in the soil and compost environments were probably due to the synergy between the diversity of microorganisms existing in these environments, together with the fungal growth that can be found in the soil and compost; aspects such as humidity and acidity play an important role, different from what occurs in the aqueous environment. 

"Based on this experience, and with the revisions we made, we could contribute a lot to the development of other materials, and we could even extrapolate these conclusions to future materials that some other researcher wants to generate, and thus produce more interest towards the end of the process of these biomaterials that are being generated," says student Fabián Steven Mosquera Rodríguez about the usefulness of his method of analysis with reference to the diversity of bets that are being made today, and that try to mitigate the impact that brings with it the use of single-use plastics.  

According to the student, at the end of the process he understood that, beyond the necessary production of biodegradable materials available to the population, it is equally or more important to establish to what extent these alternatives can fulfill the purpose for which they are developed. 

"There are many bioplastic materials or alternatives to conventional plastics, but there is not as much information on how each of these materials degrades. This research helps, even, to increase the basics of what one might encounter when faced with generating a new biocomposite," he says. 

If interested in being in touch with the students or any further information about the investigation, please write the Faculty of Engineering Communications Office: comunicaingenieria@correounivalle.edu.co.