Works presented

Summary
The retention of nitrate and phosphate in aquatic environments is crucial for maintaining ecological balance and preventing eutrophication, a phenomenon characterized by excessive algae growth due to nutrient accumulation. This leads to oxygen depletion and a consequent decline in water quality. These nutrients come from various sources, such as agricultural fertilizers, urban or industrial wastewater, making proper management and the appropriate use of products essential. Adsorption as a retention method involves the adherence of phosphates, nitrates, or other substances to the colloids present in the soil or sediments. In this study, zero-valent iron (ZVI) particles were used as an adsorbent, obtained through a green synthesis method using eucalyptus leaves, and their effectiveness under different conditions was analyzed. Additionally, the adsorptive capacity of these particles was evaluated in varying proportions combined with other materials. The results show that ZVI adsorbs phosphate present in water, with adsorption directly varying according to the concentration of the adsorbent and phosphate. Increasing the pH decreases adsorption. Conversely, nitrates are not adsorbed, meaning this anion does not interfere with phosphate adsorption. When combined with different materials, the iron particles behave differently depending on the nature of these materials. For instance, the combination with corn biochar is less effective, whereas combining with technosol or pine sawdust shows improvement, as adsorption is higher with mixed materials.

Direction
FIOL LOPEZ, SARAH (Tutorships)
ANTELO MARTINEZ, JUAN (Co-tutorships)

Court
VAZQUEZ RODRIGUEZ, SAULO ANGEL (Chairman)
BARCIELA ALONSO, Ma CARMEN (Secretary)
RIVADULLA FERNANDEZ, JOSE FRANCISCO (Member)

Summary
The technological evolution over recent years, coupled with the increasing dependence on electrical and electronic devices in our daily lives, has led to the accumulation of large tons of Waste Electrical and Electronic Equipment (WEEE) globally. This waste includes large appliances like washing machines as well as small devices like mobile phones. Managing WEEE poses a challenge due to the presence of hazardous substances such as precious metals and polymers. Although polymers are recyclable, they contain toxic elements like bisphenols and flame retardants, which, if not handled properly, can lead to environmental contamination and adverse public health effects. In this study, an analytical methodology was developed for determining bisphenols and flame retardants in WEEE plastics. The plastic types of the samples were characterized, and various protocols based on solid-liquid extraction (LSE) assisted by ultrasound (UAE) were evaluated to identify which provided the best results in terms of recovery and matrix effects. Once the sample preparation and detection method were optimized, it was applied to 30 real WEEE samples, which were analyzed using ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). Based on the results obtained, six out of the ten analytes considered in this study were detected in the analyzed samples, with concentrations ranging from 23 to 1,968,916 ng/g, BPA and TBBPA being the compounds with the highest detection frequencies and concentrations.

Direction
CASTRO VARELA, GABRIELA (Tutorships)
RODRIGUEZ PEREIRO, ISAAC (Co-tutorships)

Court
VAZQUEZ RODRIGUEZ, SAULO ANGEL (Chairman)
BARCIELA ALONSO, Ma CARMEN (Secretary)
RIVADULLA FERNANDEZ, JOSE FRANCISCO (Member)

Summary
The use of pesticides in agriculture has increased over the last few decades to improve productivity. At the same time, concern has grown in different international organisms and in the population regarding the adverse effects they can produce on the environment, on animals or on human beings. Therefore, over time, different analytical methodologies have been developed in order to evaluate the levels and control the possible impact of these compounds on the different environmental compartments. In this work, the optimization and validation of an analytical methodology based on the QuEChERS extraction has been carried out to determine pesticide residues in vineyard soils of Galicia and La Rioja with notable differences in their physicochemical properties, especially in their percentage of organic matter (% C) and in their texture. For this study, liquid chromatography coupled with mass spectrometry (LC-ESI-QqQ-MS) has been used as a determination technique. After the validation of the methodology, an analysis of real samples is carried out, both from La Rioja and Galicia, to study the dissipation and temporary evolution of pesticide residues in these soils over five campaigns.

Direction
RAMIL CRIADO, MARIA (Tutorships)

Court
VAZQUEZ RODRIGUEZ, SAULO ANGEL (Chairman)
BARCIELA ALONSO, Ma CARMEN (Secretary)
RIVADULLA FERNANDEZ, JOSE FRANCISCO (Member)

Summary
From its isolation to the present day, aluminium's properties have made it one of the most important metals in our society. It has numerous uses, mainly in the food industry, the manufacture of consumer goods, transport, construction and the military. This Final Degree Project studies in depth one of the procedures used to protect aluminium against corrosion, namely powder coating, which improves its resistance and durability. This type of treatment has given rise to an aluminium manufacturing industry that is currently in great demand. Specifically, the powder coating process carried out in the Aluminios Cortizo S.A.U. plant is described in detail, which involves pretreatment with different chemical solutions, a powder coating and a final polymerization. The different quality controls of the entire process are also described.

Direction
GONZALEZ NOYA, ANA MARIA (Tutorships)

Court
ESTEVEZ CABANAS, JUAN CARLOS (Chairman)
GARCIA SUAREZ, LUIS ALBERTO (Secretary)
Sanmartin Matalobos, Jesus (Member)

Summary
Persistent, mobile and toxic substances (PMTs) are becoming a cause of concern in the environment due to their intrinsic properties, that make their dispersion in the aquatic environment possible. The present work consists in the optimization and validation of an analytical method for the extraction and identification of PMTs present in domestic dust through the use of ultrasound assisted extraction and detection by liquid chromatography coupled to high resolution mass spectrometry, and then applying it to real samples. To optimize the extraction process, domestic dust samples spiked with 24 model chemicals (including drugs, pesticides, plastic additives, etc.). Different compositions of the extraction solvent and pH were tested in order to obtain the maximum extraction efficiency of the compounds. The results showed that a methanol based solvent with 2% formic acid offered the best results. Once the extraction conditions were selected, the methodology of suspects screening was applied to different dust samples. To do this, a library of suspects was used, which contains approximately 1100 compounds prioritized based on toxicity (T), persistence (P) and mobility (M) criteria. A total of 39 PMTs were identified (of which 21 with level 1, 10 at level 2 and 8 at level 3), according to the identification levels proposed in the literature. Compounds such as the 1,3-di-o-tolylguanidine, the 1,3-diphenylguanidine or the desethylatrazine and gentamicin, among others, could be identified in these samples.

Direction
QUINTANA ALVAREZ, JOSE BENITO (Tutorships)
PERIN , MAURICIO (Co-tutorships)

Court
VAZQUEZ RODRIGUEZ, SAULO ANGEL (Chairman)
BARCIELA ALONSO, Ma CARMEN (Secretary)
RIVADULLA FERNANDEZ, JOSE FRANCISCO (Member)

Summary
This literature review is based on the alkene metathesis reaction, a key reaction in my research project in our laboratory focused on the development of cross-linked materials, especially those with a crystalline and porous structure. In the first part, a summary of the most important porous materials is made, differentiating between crystalline and amorphous materials. On the other hand, the most important metathesis catalysts are also studied, among which are the Shrock, Grubbs and Hoveyda-Grubbs catalysts. Next, several articles are reviewed regarding the reactivity of styrene in the metathesis reaction, exploring its behavior under varying reaction conditions. The use of ionic liquids as solvents is highlighted for improving catalyst recyclability while achieving high yields. Nonetheless, the highest yields are obtained through catalyst encapsulation, a process also described. Moreover, a method combining alkene metathesis with photocatalysis to produce Z-olefins is discussed. To conclude, a series of patents is presented in which styrene or stilbene molecules (products of alkene homodimerization) are used as substrates in various reactions. These include the use of styrene as a ligand in MOF formation or the development of a product that leverages the photochromic properties of stilbene, among others.

Direction
TORNEIRO ABUIN, MERCEDES (Tutorships)

Court
ESTEVEZ CABANAS, JUAN CARLOS (Chairman)
GARCIA SUAREZ, LUIS ALBERTO (Secretary)
Sanmartin Matalobos, Jesus (Member)

Summary
This literature review is based on the analysis of dioxirane, a tricyclic organic compound characterised by a three-membered ring with two oxygen atoms of molecular form CH2O2. It was discovered in the 1970s as a very unstable and highly reactive intermediate by mechanistic and spectroscopic studies. It was soon isolated in solution, standing out for its remarkable chemical reactivity, being a powerful and selective oxidant in synthesis, particularly in epoxidations. Among the most studied derivatives is dimethyldioxirane, which can be generated in situ and which epoxidises alkenes in a stereospecific process. Its reactivity is higher with electron-rich olefins and the selectivity is marked by steric and electronic hindrances. These compounds have been applied in various chemical transformations, including the oxidation of activated C-H bonds and heteroatoms, as well as in reactions of other functional groups. The type of mechanism involved in dioxirane reactions varies depending on the substrate. In the case of epoxidations, a concerted process is observed, while with heteroatoms an SN2 type attack is observed. On the other hand, reactions with a wide variety of nucleophiles follow a heterolytic pathway and C-H bond oxidations occur via a concerted or oxygen rebound mechanism.

Direction
TOJO SUAREZ, GABRIEL (Tutorships)

Court
ESTEVEZ CABANAS, JUAN CARLOS (Chairman)
GARCIA SUAREZ, LUIS ALBERTO (Secretary)
Sanmartin Matalobos, Jesus (Member)