Non chemical natural organic matter removal with a contact TiO2 process

Dissertação de Mestrado, Tecnologia dos Alimentos, Instituto Superior de Engenharia, Universidade do Algarve, 2014

Fabrication and characterization of a nanostructured TiO2/In2S3-Sb2S3/CuSCN extremely thin absorber (eta) solar cell

CuSCN extremely thin absorber solar cell. Nanostructured TiO2 deposited by screen printing on an ITO substrate was used as an n-type electrode. An ∼80 nm extremely thin layer of the system In2S3-Sb2S3 deposited by successive ionic layer adsorption and a reaction (silar) method was used as an absorber. The voids were filled with p-type CuSCN and the entire assembly was completed with a gold contact. The solar cell fabricated with this heterostructure showed an energy conversion efficiency of 4.9%, which is a promising result in the development of low cost and simple fabrication of solar cells.

Síntese hidrotérmica assistida por micro-ondas de tiO2, e aplicação em nanocompósito

In recent decades have seen a sharp growth in the study area of nanoscience and nanotechnology and is included in this area, the study of nanocomposites with self-cleaning properties. Since titanium dioxide (TiO2) has high photocatalytic activity and also antimicrobial, self-cleaning surfaces in your application has been explored. In this study a comparison was made between two synthesis routes to obtain TiO2 nanoparticles by hydrothermal method assisted by microwave. And after analysis of XRD and SEM was considered the best material for use in nanocomposites. It was deposited nanocomposite film of poly (dimethyl siloxane) (PDMS) with 0.5, 1, 1.5 and 2% by weight of nanoparticles of titanium dioxide (TiO2) by the spraying method. The nanocomposite was diluted with hexane and the suspension was deposited onto glass substrate, followed by curing in an oven with forced air circulation. The photocatalytic activity of the nanocomposite impregnated with methylene blue was evaluated by UV- vis spectroscopy from the intensity variation of absorption main peak at 660nm with time of exposure to the UV chamber. Changes in the contact angle and microhardness were analyzed before and after UV aging test. The effect of ultraviolet radiation on the chemical structure of the PDMS matrix was evaluated by spectrophotometry Fourier transform infrared (FTIR).The results indicated that the addition of TiO2 nanoparticles in the coating PDMS gave high photocatalytic activity in the decomposition of methylene blue, an important characteristic for the development of self-cleaning coatings

Synthesis of porous graphene/TiO2 by use of recycled graphite

Graphene-based nanomaterials are a kind of new technological materials with high interest for physicists, chemists and materials scientists. Graphene is a two-dimensional (2-D) sheet of carbon atoms in a hexagonal configuration with atoms bonded by sp2 bonds. These bonds and this electron configuration provides the extraordinary properties of graphene, such as very large surface area, a tunable band gap, high mechanical strength and high elasticity and thermal conductivity [1]. Graphene has also been investigated for preparation of composites with various semiconductors like TiO2, ZnO, CdS aiming at enhanced photocatalytic activity for their use for photochemical reaction as water splitting or CO2 to methanol conversion [2-3]. In this communication, the synthesis of porous graphene@TiO2 obtained from a powder graphite recycled, supplied by ECOPIBA, is presented. This graphite was exfoliated, using a nonionic surfactant (Triton X-100) and sonication. Titanium(IV) isopropoxide was used as TiO2 source. After removing the surfactant with a solution HCl/n-propanol, a porous solid is obtained with a specific area of 358 m2g-1. The solid was characterized by XRD, FTIR, XPS, EDX and TEM. Figure 1 shows the graphene 2D layer bonded with nanoparticles of TiO2. When a water suspension of this material is exposed with UV-vis radiation, water splitting reaction is carried out and H2/O2 bubbles are observed (Figure 2)

Cascaded all-optical sub-channel add/drop multiplexing from a 1-Tb/s super-channel having 2-GHz guard-bands

We demonstrate cascaded 100-Gb/s sub-channel add/drop from a 1-Tb/s multi-band OFDM super-channel having 2-GHz inter-sub-channel guard-bands within a recirculating loop via a hierarchical ROADM using high-resolution filters, showcasing 1000-km transmission reach and five ROADM node passages for the add/drop sub-channel when hybrid Raman-EDFA is implemented.

Isolating the photovoltaic junction: atomic layer deposited TiO2-RuO2 alloy Schottky contacts for silicon photoanodes

We synthesized nanoscale TiO2-RuO2 alloys by atomic layer deposition (ALD) that possess a high work function and are highly conductive. As such, they function as good Schottky contacts to extract photogenerated holes from n-type silicon while simultaneously interfacing with water oxidation catalysts. The ratio of TiO2 to RuO2 can be precisely controlled by the number of ALD cycles for each precursor. Increasing the composition above 16% Ru sets the electronic conductivity and the metal work function. No significant Ohmic loss for hole transport is measured as film thickness increases from 3 to 45 nm for alloy compositions >= 16% Ru. Silicon photoanodes with a 2 nm SiO2 layer that are coated by these alloy Schottky contacts having compositions in the range of 13-46% Ru exhibit average photovoltages of 525 mV, with a maximum photovoltage of 570 mV achieved. Depositing TiO2-RuO2 alloys on nSi sets a high effective work function for the Schottky junction with the semiconductor substrate, thus generating a large photovoltage that is isolated from the properties of an overlying oxygen evolution catalyst or protection layer.

Implémentation sur FPGA de l’algorithme MUSIC sur antenne-réseau expérimentale à 10 GHz

Les techniques des directions d’arrivée (DOA) sont une voie prometteuse pour accroitre la capacité des systèmes et les services de télécommunications en permettant de mieux estimer le canal radio-mobile. Elles permettent aussi de suivre précisément des usagers cellulaires pour orienter les faisceaux d’antennes dans leur direction. S’inscrivant dans ce contexte, ce présent mémoire décrit étape par étape l’implémentation de l’algorithme de haut niveau MUSIC (MUltiple SIgnal Classification) sur une plateforme FPGA afin de déterminer en temps réel l’angle d’arrivée d’une ou des sources incidentes à un réseau d’antennes. Le concept du prototypage rapide des lois de commande (RCP) avec les outils de XilinxTM System generator (XSG) et du MBDK (Model Based Design Kit) de NutaqTM est le concept de développement utilisé. Ce concept se base sur une programmation de code haut niveau à travers des modèles, pour générer automatiquement un code de bas niveau. Une attention particulière est portée sur la méthode choisie pour résoudre le problème de la décomposition en valeurs et vecteurs propres de la matrice complexe de covariance par l’algorithme de Jacobi. L’architecture mise en place implémentant cette dernière dans le FPGA (Field Programmable Gate Array) est détaillée. Par ailleurs, il est prouvé que MUSIC ne peut effectuer une estimation intéressante de la position des sources sans une calibration préalable du réseau d’antennes. Ainsi, la technique de calibration par matrice G utilisée dans ce projet est présentée, en plus de son modèle d’implémentation. Enfin, les résultats expérimentaux du système mis à l’épreuve dans un environnement réel en présence d’une source puis de deux sources fortement corrélées sont illustrés et analysés.

Degradação de glifosato por fotocatálise heterogênea utilizando filmes finos de TiO2 suportados em anéis de quartzo seguida de análise por cromatografia líquida com detecção por fluorescência.

2006

Determinação de dióxido de titânio (TiO2) em fezes de bovinos de corte utilizado como marcador externo por ICP OES.

2016

Sintesi di compositi nanostrutturati a base di TiO2 per la depurazione delle acque

Lo scopo di questo lavoro di tesi consiste nella realizzazione di fotocatalizzatori a base di nano-TiO2 per potenziali applicazioni nel campo della depurazione delle acque reflue. Nello specifico sono stati sintetizzati nanocompositi accoppiando nano-TiO2 a due materiali grafitici: ossido di grafene (GO), tramite ultrasonicazione (TGO) e nitruro di carbonio grafitico (g-C3N4), attraverso due tecniche: ultrasonicazione e polimerizzazione termica in situ. Per i compositi TGO lo studio relativo alla sintesi è stato rivolto all’ottimizzazione della percentuale in peso di GO. Per i compositi a base di g-C3N4 lo scopo è stato quello di valutare quale dei due metodi di sintesi fosse il più efficace. I materiali ottenuti sono stati caratterizzati dal punto di vista chimico-fisico (DLS-ELS, XRD, Band Gap, BET, SEM, FT-IR, TGA-DSC) e funzionale. La caratterizzazione funzionale è stata eseguita per valutare le prestazioni fotocatalitiche dei fotocatalizzatori nanocompositi utilizzando, come reazione modello, la fotodegradazione di Rodamina B, sotto luce UV e solare. I risultati hanno messo in luce che la percentuale ottimale di GO, nei compositi TGO, è pari al 16%. Inoltre, è stato osservato un effetto sinergico tra TiO2 e GO dove i nanocompositi TGO hanno mostrato maggiore attività fotocatalitiche rispetto alla singola TiO2. I dati fotocatalitici hanno evidenziato che il metodo ottimale per la preparazione dei compositi a base di g-C3N4 e TiO2, è la polimerizzazione termica in situ a 500°C.

Electrochemical Oxidation Of Landfill Leachate In A Flow Reactor: Optimization Using Response Surface Methodology.

Response surface methodology based on Box-Behnken (BBD) design was successfully applied to the optimization in the operating conditions of the electrochemical oxidation of sanitary landfill leachate aimed for making this method feasible for scale up. Landfill leachate was treated in continuous batch-recirculation system, where a dimensional stable anode (DSA(©)) coated with Ti/TiO2 and RuO2 film oxide were used. The effects of three variables, current density (milliampere per square centimeter), time of treatment (minutes), and supporting electrolyte dosage (moles per liter) upon the total organic carbon removal were evaluated. Optimized conditions were obtained for the highest desirability at 244.11 mA/cm(2), 41.78 min, and 0.07 mol/L of NaCl and 242.84 mA/cm(2), 37.07 min, and 0.07 mol/L of Na2SO4. Under the optimal conditions, 54.99 % of chemical oxygen demand (COD) and 71.07 ammonia nitrogen (NH3-N) removal was achieved with NaCl and 45.50 of COD and 62.13 NH3-N with Na2SO4. A new kinetic model predicted obtained from the relation between BBD and the kinetic model was suggested.

Photocatalytic Degradation Of Ofloxacin And Evaluation Of The Residual Antimicrobial Activity.

Ofloxacin is an antimicrobial agent frequently found in significant concentrations in wastewater and surface water. Its continuous introduction into the environment is a potential risk to non-target organisms or to human health. In this study, ofloxacin degradation by UV/TiO2 and UV/TiO2/H2O2, antimicrobial activity (E. coli) of samples subjected to these processes, and by-products formed were evaluated. For UV/TiO2, the degradation efficiency was 89.3% in 60 min of reaction when 128 mg L(-1) TiO2 were used. The addition of 1.68 mmol L(-1) hydrogen peroxide increased degradation to 97.8%. For UV/TiO2, increasing the catalyst concentration from 4 to 128 mg L(-1) led to an increase in degradation efficiency. For both processes, the antimicrobial activity was considerably reduced throughout the reaction time. The structures of two by-products are presented: m/z 291 (9-fluoro-3-methyl-10-(methyleneamino)-7-oxo-2,3-dihydro-7H-[1,4]oxazino[2,3,4-ij]quinoline-6-carboxylic acid) and m/z 157 ((Z)-2-formyl-3-((2-oxoethyl)imino)propanoic acid).

Estimativas do teor de umidade empregando o método GPR: uma avaliação comparativa em experimentos de laboratório e campo

Este trabalho faz uma análise das estimativas de teores de umidade obtidas com o método Ground Penetrating Radar (GPR) comparativamente às determinadas com os métodos Time Domain Reflectometry (TDR) e gravimétrico. Os dados foram obtidos em dois experimentos diferentes: um experimento controlado em laboratório buscando reproduzir um meio homogêneo onde foram obtidas as medidas de umidade com GPR (antenas de 1 GHz) e TDR, e outro experimento de campo onde foram obtidos dados com GPR (antenas de 200 MHz) e de amostras de solos do local. Para a obtenção das estimativas a partir do método GPR foram analisados os eventos relativos à onda de transmissão direta entre as antenas, onda refratada criticamente e onda refletida em interfaces com diferentes propriedades elétricas.O GPR mostrou-se sensível às variações de umidades presentes nos dois experimentos e apresentou boa correlação com os dados obtidos com TDR (REQM de0,007 m³m-3) e das amostras (REQM de 0,039 m³m-3).