Chemical recycling of municipal packaging waste by pyrolysis

[EN]The present doctoral thesis centers on studying pyrolysis as a chemical recycling technique for rejected packaging waste fractions coming from separation and sorting plants. The pyrolysis experiments have been carried out in a lab-scale installation equipped with a 3.5 L semi-batch reactor and a condensation and collection system for the liquids and gases generated. In the present thesis, an experimental study on the conventional pyrolysis process applied to the aforementioned waste fractions has been conducted, as well as the study of non-conventional or advanced pyrolysis processes such as catalytic and stepwise pyrolysis. The study of the operating parameters has been carried out using a mixed plastics simulated sample, the composition of which is similar to that found in real fractions, and subsequently the optimized process has been applied to real packaging waste. An exhaustive characterization of the solids, liquids and gases obtained in the process has been made after each experiment and their potential uses have been established. Finally, an empirical model that will predict the pyrolysis yields (% organic liquid, % aqueous liquid, % gases, % char, % inorganic solid) as a function of the composition of the initial sample has been developed. As a result of the experimental work done, the requirements have been established for an industrial packaging waste pyrolysis plant that aims to be sufficiently versatile as to generate useful products regardless of the nature of the raw material.

Tracking the evolution of waste recycling research using overlay maps of science

Tracking the evolution of research in waste recycling science (WRS) can be valuable for environmental agencies, as well as for recycling businesses. Maps of science are visual, easily readable representations of the cognitive structure of a branch of science, a particular area of research or the global spectrum of scientific production. They are generally built upon evidence collected from reliable sources of information, such as patent and scientific publication databases. This study uses the methodology developed by Rafols et al. (2010) to make a “double overlay map” of WRS upon a basemap reflecting the cognitive structure of all journal-published science, for the years 2005 and 2010. The analysis has taken into account the cognitive areas where WRS articles are published and the areas from where it takes its intellectual nourishing, paying special attention to the growing trends of the key areas. Interpretation of results lead to the conclusion that extraction of energy from waste will probably be an important research topic in the future, along with developments in general chemistry and chemical engineering oriented to the recovery of valuable materials from waste. Agricultural and material sciences, together with the combined economics, politics and geography field, are areas with which WRS shows a relevant and ever increasing cognitive relationship.

Ionic Liquids and Cellulose: Dissolution, Chemical Modification and Preparation of New Cellulosic Materials

Due to its abundance and a wide range of beneficial physical and chemical properties, cellulose has become very popular in order to produce materials for various applications. This review summarizes the recent advances in the development of new cellulose materials and technologies using ionic liquids. Dissolution of cellulose in ionic liquids has been used to develop new processing technologies, cellulose functionalization methods and new cellulose materials including blends, composites, fibers and ion gels.

From Gods to men: A historical overview of the discovery of the chemical elements

To achieve the apparently simple Periodic Table of the Elements has implied tremendous efforts over thousands of years. In this paper we present a brief history of the discovery of the chemical elements from prehistory to the present day, revealing the controversies that arose on the way and claiming the important work performed by alchemists in the advancement of knowledge. This is especially important if we consider that alchemy had a period of existence of many thousands of years, while the "Chemistry", officially established as a science in the eighteenth century, has operated as such for only a few hundred years. Even so, if we consider the progress of discovery and isolation of chemical elements throughout history, it can be observed that the number of elements identified is achieved mainly in the nineteenth and twentieth centuries, reflecting the development of instrumental techniques, that facilitated this task.

Physico-chemical interactions between compartment-forming lipids and other prebiotically relevant biomolecules

Lipids are essential constituents of contemporary living cells, serving as structural molecules that are necessary to form membranous compartments. Amphiphilic lipid-like molecules may also have contributed to prebiotic chemical evolution by promoting the synthesis, aggregation and cooperative encapsulation of other biomolecules. The resulting compartments would allow systems of molecules to be maintained that represent microscopic experiments in a natural version of combinatorial chemistry. Here we address these possibilities and describe recent results related to interactions between amphiphiles and other biomolecules during early evolution toward the first living cells.