Faceted nanomaterial synthesis, characterizations and applications in reactive electrochemical membrane filtration

Facet engineering of nanomaterials, especially metals and metal oxides has become an important strategy for tuning catalytic properties and functions from heterogeneous catalysis to electrochemical catalysis, photocatalysis, biomedicine, fuel cells, and gas sensors. The catalytic properties are highly related to the surface electronic structures, surface electron transport characteristics, and active center structures of catalysts, which can be tailored by surface facet control. The aim of this doctoral dissertation research is to study the facet-dependent properties of metal or metal oxide nanoparticles using multiple advanced characterization techniques. Specifically, the novel atomic force microscope-scanning electrochemical microscope (AFM-SECM) and density functional theory (DFT) calculations were both applied to both experimentally and theoretically investigate facet dependent electrochemical properties, molecular adsorption, and dissolution properties of cuprous oxide and silver nanoparticles. To promote the facet engineered nanomaterials for environmental engineering apparitions, our research has evaluated the performances of electrochemically reactive membranes that were prepared with novel 2D nanomaterials with surface functioal modifications to enable electrochemical advanced oxidation processes (EAOPs) in membrane filtration process. Our results demonstrated many advantages such as tunable reactivity, tailored surface reactions, antifouling features, and feasibility of large-scale continuous operations. Specifically, this dissertation will introduce our electrochemical membrane synthesis, reactivity, aging, byproducts formation and electrochemical adsorption and desorption, oxidation of pollutants such as two typical per-and poly-fluoroalkyl substances (PFAS), perfluorooctanoic Acid (PFOA) and perfluorobutanoic acid (PFBA)

Chapter 34 - Biocompatibility of nanocellulose: Emerging biomedical applications

Nanocellulose already proved to be a highly relevant material for biomedical applications, ensued by its outstanding mechanical properties and, more importantly, its biocompatibility. Nevertheless, despite their previous intensive research, a notable number of emerging applications are still being developed. Interestingly, this drive is not solely based on the nanocellulose features, but also heavily dependent on sustainability. The three core nanocelluloses encompass cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs), and bacterial nanocellulose (BNC). All these different types of nanocellulose display highly interesting biomedical properties per se, after modification and when used in composite formulations. Novel applications that use nanocellulose includewell-known areas, namely, wound dressings, implants, indwelling medical devices, scaffolds, and novel printed scaffolds. Their cytotoxicity and biocompatibility using recent methodologies are thoroughly analyzed to reinforce their near future applicability. By analyzing the pristine core nanocellulose, none display cytotoxicity. However, CNF has the highest potential to fail long-term biocompatibility since it tends to trigger inflammation. On the other hand, neverdried BNC displays a remarkable biocompatibility. Despite this, all nanocelluloses clearly represent a flag bearer of future superior biomaterials, being elite materials in the urgent replacement of our petrochemical dependence

Spacelab Science Results Study

Beginning with OSTA-1 in November 1981 and ending with Neurolab in March 1998, a total of 36 Shuttle missions carried various Spacelab components such as the Spacelab module, pallet, instrument pointing system, or mission peculiar experiment support structure. The experiments carried out during these flights included astrophysics, solar physics, plasma physics, atmospheric science, Earth observations, and a wide range of microgravity experiments in life sciences, biotechnology, materials science, and fluid physics which includes combustion and critical point phenomena. In all, some 764 experiments were conducted by investigators from the U.S., Europe, and Japan. The purpose of this Spacelab Science Results Study is to document the contributions made in each of the major research areas by giving a brief synopsis of the more significant experiments and an extensive list of the publications that were produced. We have also endeavored to show how these results impacted the existing body of knowledge, where they have spawned new fields, and if appropriate, where the knowledge they produced has been applied

Conversão catalítica de sacarídeos em 2-furaldeído e 5-hidroximetil-2-furaldeído

Doutoramento em QuímicaThe conversion of plant biomass-derived carbohydrates (preferably non-edible) into added-value products is envisaged to be at the core of the future biorefineries. Carbohydrates are the most abundant natural organic polymers on Earth. This work deals with the chemical valorisation of plant biomass, focusing on the acid-catalysed conversion of carbohydrates (mono and polysaccharides) to furanic aldehydes, namely 2-furaldehyde (Fur) and 5-hydroxymethyl-2-furaldehyde (Hmf), which are valuable platform chemicals that have the potential to replace a variety of oil derived chemicals and materials. The investigated reaction systems can be divided into two types depending on the solvent used to dissolve the carbohydrates in the reaction medium: water or ionic liquid-based systems. The reaction temperatures were greater than 150 ºC when the solvent was water, and lower than 150 º C in the cases of the ionic liquid-based catalytic systems. As alternatives to liquid acids (typically used in the industrial production of Fur), solid acid catalysts were investigated in these reaction systems. Aiming at the identification of (soluble and insoluble) reaction products, complementary characterisation techniques were used namely, FT-IR spectroscopy, liquid and solid state NMR spectroscopy, TGA, DSC and GC´GC-ToFMS analyses. Complex mixtures of soluble reaction products were obtained and different types of side reactions may occur. The requirements to be put on the catalysts for these reaction systems partly depend on the type of carbohydrates to be converted and the reaction conditions used. The thermal stability is important due to the fact that formation of humins and catalyst coking phenomena are characteristically inherent to these types of reactions systems leading to the need to regenerate the catalyst which can be effectively accomplished by calcination. Special attention was given to fully inorganic nanoporous solid acids, amorphous or crystalline, and consisting of nano to micro-size particles. The investigated catalysts were silicoaluminophosphates, aluminosilicates and zirconium-tungsten mixed oxides which are versatile catalysts in that their physicochemical properties can be fine-tuned to improve the catalytic performances in the conversion of different substrates (e.g. introduction of mesoporosity and modification of the acid properties). The catalytic systems consisting of aluminosilicates as solid acids and water as solvent seem to be more effective in converting pentoses and related polysaccharides into Fur, than hexoses and related polysaccharides into Hmf. The investigated solid acids exhibited fairly good hydrothermal stabilities. On the other hand, ionic liquid-based catalytic systems can allow reaching simultaneously high Fur and Hmf yields, particularly when Hmf is obtained from D-fructose and related polysaccharides; however, catalyst deactivation occurs and the catalytic reactions take place in homogeneous phase. As pointed out in a review of the state of the art on this topic, the development of truly heterogeneous ionic liquid-based catalytic systems for producing Fur and Hmf in high yields remains a challenge.Os carboidratos constituem os polímeros naturais mais abundantes na Terra, e a sua valorização química é de grande interesse no contexto das biorefinarias. O objetivo deste trabalho centrou-se na conversão de carboidratos (monossacarídeos e polissacarídeos) em 2-furaldeído (Fur) e 5-hidroximetil-2-furaldeído (Hmf) na presença de catalisadores ácidos, em reatores descontínuos. Fur e Hmf são considerados compostos “plataforma” porque podem ser convertidos numa grande variedade de produtos químicos e materiais (alternativos aos derivados do petróleo). Testaram-se catalisadores ácidos heterogéneos como alternativa aos ácidos minerais que são comumente usados como catalisadores homogéneos para a produção industrial do Fur. Por outro lado utilizou-se água ou um líquido iónico como solvente para a dissolução dos carboidratos no meio reacional. As temperaturas reacionais foram superiores a 150 ºC quando o solvente era a água, e inferiores a 150 ºC no caso de líquidos iónicos. Com o intuito de identificar os produtos reacionais (solúveis e insolúveis), utilizaram-se diferentes técnicas nomeadamente espetroscopia de infravermelho, espetroscopia de RMN de estado líquido e sólido, TGA, DSC e GCxGC-ToFMS. Obtiveram-se misturas complexas de produtos reacionais e discutiram-se aspetos mecanísticos. A estabilidade térmica do catalisador é importante uma vez que a formação de matéria carbonácea insolúvel é característica destes sistemas reacionais tornando-se necessário proceder à regeneração do catalisador por calcinação. Os catalisadores testados foram ácidos inorgânicos nanoporosos, cristalinos ou amorfos, com tamanho de partícula nano ou micrométrico, especificamente silicoaluminofosfatos, aluminossilicatos e óxidos mistos de zircónio e tungsténio. Estes tipos de materiais são versáteis uma vez que as suas propriedades físicoquímicas podem ser modificadas no sentido de melhorar os seus desempenhos catalíticos na conversão de diferentes tipos de substratos (ex. através da criação de mesoporos nos materiais e/ou modificação das propriedades ácidas). Os materiais testados exibiram melhores desempenhos catalíticos para a conversão de pentoses em Fur do que para a de hexoses em Hmf, quando o solvente era a água. Em suma, os catalisadores apresentaram boa estabilidade hidrotérmica. No caso dos sistemas reacionais à base de líquidos iónicos foram verificados elevados rendimentos em Fur e Hmf. especialmente quando os substratos eram a D-frutose ou polissacarídeos relacionados. Contudo, os catalisadores sofreram desativação tal que as reações catalíticas ocorreram em fase homogénea. Conforme explicado numa revisão bibliográfica sobre o estado da arte da conversão catalítica de carboidratos em Fur e Hmf usando líquidos iónicos, o desenvolvimento de sistemas catalíticos heterogéneos à base de líquidos iónicos representa um grande desafio

Synthesis of new pyrazolium based tunable aryl alkyl ionic liquids and their use in removal of methylene blue from aqueous solution

In this study, two new pyrazolium based tunable aryl alkyl ionic liquids, 2-ethyl-1-(4-methylphenyl)-3,5- dimethylpyrazolium tetrafluoroborate (3a) and 1-(4-methylphenyl)-2-pentyl-3,5-dimethylpyrazolium tetrafluoroborate (3b), were synthesized via three-step reaction and characterized. The removal of methylene blue (MB) from aqueous solution has been investigated using the synthesized salts as an extractant and methylene chloride as a solvent. The obtained results show that MB was extracted from aqueous solution with high extraction efficiency up to 87 % at room temperature at the natural pH of MB solution. The influence of the alkyl chain length on the properties of the salts and their extraction efficiency of MB was investigated

Food science sourcebook

2 v. : ill. ; 26 cm2nd edition.Rev. ed. of: Source book for food scientists. c1978"An AVI book."Pt. 1. Terms and descriptions -- pt. 2. Food composition,properties, and general data