Aplicación de técnicas de encapsulación para la incorporación de aditivos en la formulación de detergentes

Zusammenfassung

The detergent industry faces increasingly stringent quality standards characterized by higher washing effectiveness requirements and improved selectivity for the removal of specific soils. Within this context, the importance of environmental sustainability is gaining prominence due to the widespread and continuous use of detergents in both domestic and industrial settings. The incorporation of additives into formulations becomes a crucial strategy to add value to the product. However, many of the essential additives to enhance detergent performance are susceptible to instability, either due to external physical stimuli or intrinsic incompatibility with other compounds present in the detergent formulation. In response to these challenges, the utilization of encapsulation techniques emerges as a key tool for protecting sensitive substances present in detergents. This innovative approach involves confining these substances within solid particles, offering effective solutions without the use of high amounts of energy or organic solvents associated with emulsion formation for capsule creation. This method not only optimizes process efficiency but also proves to be more environmentally friendly. Encapsulation of additives in detergent formulations presents additional advantages by allowing controlled release of these compounds from inside the capsules. This control is achieved through an external stimulus, enabling precise dosing at the opportune moment during the washing cycle. This strategy not only improves the stability of additives but also significantly contributes to environmental sustainability by avoiding uncontrolled release of potentially harmful substances. Overall, encapsulation emerges as a comprehensive solution that combines technical efficiency and environmental considerations in the development of advanced detergents. This Doctoral Thesis is divided into six well-defined parts. The introduction presents the contextualization and existing issues that generate the need for this work. Subsequently, the general objective and specific objectives for its achievement are outlined. The Materials section presents the chemical compounds used for different procedures. Following this, the Methodology section explains the techniques used for equipment usage, capsule formation, characterization, coating techniques, and release, classified according to the material used for capsule formation. Similarly, in the Results Discussion section, the obtained results are presented, organized in the same manner as the previous section and divided into three chapters: the first chapter tests silica nanoparticles, the second latex, and the third chitosan and Arabic gum. Finally, the main conclusions drawn are presented. The main objective of the thesis is the optimization of different methodologies for the formation of capsules using various materials to incorporate additives of interest for inclusion in detergent formulations. To achieve this objective, a series of specific objectives are followed, such as exploring different techniques and materials that meet all the necessary requirements for obtaining capsules capable of retaining different additives and achieving their controlled release. This includes applying coatings compatible with the capsule wall material, serving a dual function: providing waterproofing to the capsule and imparting antimicrobial properties. Finally, the effectiveness of encapsulation is quantified by determining the amount of encapsulated material that can be released from inside the capsules. As explained, both the methodology and the results of this work are presented in order according to the colloidal material used for stabilizing Pickering emulsions and capsule formation. Firstly, the ability of different types of silica nanoparticles to form capsules from emulsions is tested. In the case of Aerosil™ A200, although capsule formation is achieved, they exhibit high instability, leading to the utilization of Ludox™ silica nanoparticles. The objective is to encapsulate a biocide agent like Bronopol. Initially, porous capsules capable of transporting the active compound are obtained, but without retaining it inside. Hence, the study focuses on applying coatings of different natures to achieve controlled release of the biocide, achieving the best results using chitosan to form a film around the Ludox™ silica capsules. The next step involves the use of a synthetic polymer like latex for capsule formation with the aim of encapsulating enzymes. Nanoparticles synthesis is carried out using three monomers, and two different methods are tested for colloid formation. After confirming capsule permeability in dilution tests, additional coating layers are required to seal them. Total retention of the internal compound is achieved by applying copper and silver metallic coatings, protecting the core. Once controlled release is induced by rupturing the capsule walls, high encapsulation efficiencies are attained. The encapsulation of bioactive agents through the utilization of biodegradable nanoparticles is a topic of considerable scientific interest. In this study, microcapsules composed of chitosan (CS) and Arabic gum (GA) nanoparticles were synthesized, encapsulating oregano essential oil (OEO) through Pickering emulsions and subsequent spray drying. The optimization of hybrid chitosan and Arabic gum (CS–GA) nanoparticle formation was carried out via complex coacervation, followed by an assessment of their behavior during the formation of the emulsion. Measurements of the size, contact angle, and interfacial tension of the formed complexes were conducted to facilitate the development of Pickering emulsions for encapsulating the oil under the most favorable conditions. The chitosan–Arabic gum capsules were physically characterized using scanning electron microscopy and fitted to the Beerkan estimation of soil transfer (BEST) model to determine their size distribution. Finally, the OEO encapsulation efficiency was also determined. The optimum scenario was achieved with the CS–GA 1–2 capsules at a concentration of 2% wt, featuring a contact angle of 89.1 degrees, which is ideal for the formation of oil/water (O/W) emulsions. Capsules of approximately 2.5 μm were obtained, accompanied by an encapsulation efficiency of approximately 60%. An important point in detergent formulation is the utilization of compounds that allow high biodegradability to avoid limitations imposed by increasingly restrictive regulations. Therefore, a study on the biodegradability and environmental effects of all nanoparticles used for capsule formation is conducted. This study aims to provide fundamental insights into the employed nanoparticles, and the presented results will be valuable for future applications in environmentally friendly detergent formulations. Overall, from the studies conducted in the doctoral thesis, it can be concluded that the optimization of capsule production techniques has been achieved using various materials: silica, latex, chitosan, and Arabic gum for the inclusion of enzymes, a biocide agent, and oregano essential oil, respectively. Furthermore, it has been demonstrated that the use of silver, copper, and chitosan as capsule coating materials not only allows their antimicrobial capacity but also contributes to stabilization.