Development of porous alumina membranes for treatment of textile effluent

Published online: 27 Feb 2015Ceramic porous membranes sintered at two different temperature using polyvinyl alcohol and ethylene glycol as binders, and composed of two types of α-alumina with different particle sizes were investigated for the microfiltration of a textile effluent containing indigo dye, auxiliaries, heavy metals, oils, and solids. The physicochemical properties of the membranes and effluent were evaluated. X-ray diffraction, energy dispersive X-ray fluorescence spectroscopy, differential scanning calorimetry, and thermogravimetric analysis confirm that the thin membrane is composed of high crystalline and pure α-alumina. Scanning electron microscopy observation indicates that the membranes have smooth porous surface making it suitable for microfiltration applications. The membrane sintered at 1,450˚C exhibited higher water absorption (WA) and apparent porosity than that sintered at 1,475˚C. The apparent specific gravity and flexural strength are in inverse correlation with the WA due to the enhanced densification of the membranes. The filtered effluent was evaluated using a membrane with an average pore size of 0.4 μm and a total porosity of 29.6%. The average values of rejection were 90% for color, 93% for suspended solids, 95% for turbidity, 60% for metals, and 73% for chemical oxygen demand. These results demonstrate that low-cost ceramic alumina membranes are a very promising advanced treatment for textile industrial effluents.Andrea Zille (C2011- UMINHO-2C2T-01) acknowledges funding from Programa Compromisso para a Ciencia 2008, Portugal

Photocatalytic Activity and UV-Protection of TiO(2) Nanocoatings on Poly(lactic acid) Fibres Deposited by Pulsed Magnetron Sputtering

The application of nanocoatings in the textile finishing is increasingly being explored because they open a whole new vista of value-addition possibilities in the textile sector. In the present work, low temperature pulsed DC magnetron sputtering method was used to create functional TiO2 nanocoatings on poly(lactic acid) textile fibres surfaces. In this study, the principal objectives in the application of TiO2 nanocoatings to textile materials are to impart UV protection functions and self-cleaning properties to the textile substrates. The TiO2 films were characterized by X-ray diffraction, scanning electron microscopy, atomic force microscopy, transmission electron microscopy, UV-visible spectroscopy and contact angle analysis. The Photocatalytic activity of the films was tested by measuring the photodegradation rates of rhodamine-B dye aqueous solution under UV light irradiation. The ultraviolet protection function was tested according to the Australian/New Zealand standards. It was observed that the TiO2 nanocoatings on poly(lactic acid) fibres showed an excellent ultraviolet protection (>40) function and the photocatalytic efficiency was maintained even after a strong washing treatment.We acknowledge the PhD grant of J. H. O. Nascimento to Programa ALBAN-"Programa de bolsas de alto nivel da Uniao Europeia para a America Latina, bolsa no E06D104090BR.

Surface modification of bamboo fibers using chitosan and functionalization with AuNPs

In this work, a new surface modification of the bamboo substrate with chitosan was studied, followed by subsequent treatment with gold nanoparticles (AuNP) by the exhaustion method, aiming at obtaining a technical textile with ultraviolet (UV) protection. The treatment with chitosan in the bamboo substrate induced an increase in the AuNP adsorption due to the electrostatic interactions between the chitosan amino groups and the citrate ion that surrounds the AuNP. The nanoparticles were obtained by the chemical reduction method, with some adaptations, using sodium citrate as a reducing agent/stabilizer and chlorouronic acid as precursor. The AuNP were characterized by transmission electron microscopy (TEM) and reflection, showing an average size of 35 nm. The presence of AuNP on the fiber surface was confirmed by SEM and XRD, with crystallographic peaks characteristic of gold. The UV protection factor was tested on the material, demonstrating excellent results.info:eu-repo/semantics/publishedVersio

Multifunctional chitosan/gold nanoparticles coatings for biomedical textiles

Gold nanoparticles (AuNPs), chemically synthesized by citrate reduction, were for the first time immobilized onto chitosan‐treated soybean knitted fabric via exhaustion method. AuNPs were successfully produced in the form of highly spherical, moderated polydisperse, stable structures. Their average size was estimated at ≈35 nm. Successful immobilization of chitosan and AuNPs were confirmed by alterations in the fabric’s spectrophotometric reflectance spectrum and by detection of nitrogen and gold, non‐conjugated C=O stretching vibrations of carbonyl functional groups and residual N‐acetyl groups characteristic bands by X‐ray photoelectron spectroscopy (XPS) and Fourier‐Transform Infrared Spectroscopy (FTIR) analysis. XPS analysis confirms the strong binding of AuNPs on the chitosan matrix. The fabrics’ thermal stability increased with the introduction of both chitosan and AuNPs. Coated fabrics revealed an ultraviolet protection factor (UPF) of +50, which established their effectiveness in ultraviolet (UV) radiation shielding. They were also found to resist up to 5 washing cycles with low loss of immobilized AuNPs. Compared with AuNPs or chitosan alone, the combined functionalized coating on soy fabrics demonstrated an improved antimicrobial effect by reducing Staphylococcus aureus adhesion (99.94%) and Escherichia coli (96.26%). Overall, the engineered fabrics were confirmed as multifunctional, displaying attractive optical properties, UV‐light protection and important antimicrobial features, that increase their interest for potential biomedical applications.: This research was funded by FEDER funds through the Operational Competitiveness Program – COMPETE and by National Funds through Fundação para a Ciência e Tecnologia (FCT) under the project POCI‐ 01‐0145‐FEDER‐007136 and UID/CTM/00264/2019. A. Zille also acknowledges financial support of the FCT through an Investigator FCT Research contract (IF/00071/2015) and the project PTDC/CTM‐TEX/28295/2017 financed by FCT, FEDER and POCI. This work was funded by FEDER funds through the Operational Competitiveness Program – COMPETE and by National Funds through Fundação para a Ciência e Tecnologia (FCT)—under the project POCI‐01‐0145‐FEDER‐007136 and UID/CTM/00264/2019. A. Zille also acknowledges financial support of the FCT through an Investigator FCT Research contract (IF/00071/2015) and the project PTDC/CTM‐ TEX/28295/2017 financed by FCT, FEDER and POCI

Production of photocatalytic road pavements using TiO2 nanoparticles

posterMan’s activity and mismanagement of resources conducted to dangerous levels of pollution in water, air and earth and to incalculable deficiencies, harmful to the physical and social health of mankind. Industrial activities, heating systems and road traffic are the main responsibles for the emission of pollutant gases such as nitrogen oxides (NOx) and volatile organic compounds (VOCs). As so, its harmful impacts are observed far beyond large cities and jam-packed streets. It is important to refer that the health costs related only with road traffic air pollution represents 0.9%-2.7% of the gross domestic product (GDP) in France, for example. Under this context, the combination of nanostructured titanium dioxide (TiO2) and bituminous formulations represents a tool, with considerable degree of innovation, towards the reduction of environmental impacts. In this work, conventional hot mix asphalt (HMA) was produced with standard materials to play the role of a control sample. Afterwards, an aqueous solution of TiO2 nanoparticles was sprayed over sample’s surface. By another hand, a HMA samples was also modified through the volume incorporation of small quantities of TiO2 nanoparticles and recycled glass cullets. It is expected that the inclusion of glass in the asphalt formulations should promote an in-depth conduction and entrapment of light , thus enhancing the photocatalytic performance of this samples. Scanning Electron Microscopy (SEM) analysis were conducted in order to infer about the morphology of the modified HMA samples and the surface as well as the in-depth dispersion of TiO2 nanoparticles and recycled glass cullets. The produced samples were also subjected to wearing tests using the tire-road contact method. Before and after the wearing process, the photocatalytic efficiency was evaluated via the decomposition rate of an aqueous solution of Methylene Blue (MB) under UV light irradiation

Study of tinctorial behaviour of curaua and banana fibres

The ecological benefits of renewable raw materials are clear: they save valuable resources, are environmentally sound and do not cause health problems. Natural fibres have already established a track record in several different areas such as, civil, automobiles, architecture, medicine among others. Numerous investigations are carried out in order to create added value to natural fibre materials such as the stem of the banana tree that are usually discarded in the environment. Curaua, another important natural substrate, is an Amazon-forest plant (Ananas erectifolius) that resembles a pineapple plant. Curaua leaf fibres display a low-production cost and offer a relatively high tensile strength level. Despite these naturals fibres are well established as reinforce in composite materials, the dyeing properties of curaua and banana fibres are not well studied yet.This work is supported by Portuguese National Funding, through FCT - Fundação para a Ciência e a Tecnologia, on the framework of project UID/CTM/00264/2013

Tinctorial behavior of curaua and banana fibers and dyeing wastewater treatment by porous alumina membranes

Physicochemical and dyeing properties using reactive dyes of curaua and banana fibers were studied by means of color strength (K/S), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) spectroscopy analyses. SEM analysis of alkali-treated fibers showed an increase in roughness due to surface lignin and hemicellulose defibrillation. DSC analysis showed for all the samples an endothermic and an exothermic peak at 70–80 and 340–360 ̊C due to the loss of adsorbed/ absorbed water and to decomposition of α-cellulose, respectively. Alkali-treated fibers dis- played a second peak around 290 ̊C attributed to the degradation of hemicellulose. FTIR spectra of the studied fibers show similar bands with different intensities attributed to the main components of cellulose-based materials. Alkali-pretreated fibers demonstrated excel- lent dyeing ability for all the tested dyes. Dye absorption depends on the chemical fiber, dye structure, and concentration. The results of washing fastness are very good for all the tested fibers. The dyeing effluent treated with an advanced microfiltration method using an improved alumina ceramic membrane shows an average efficiency of 98% in turbidity and color reduction. Low-cost ceramic alumina microfiltration membranes are a very promising advanced treatment for textile industrial effluents allowing water reuse.C2011-UMINHO-2C2T-01 acknowledges the funding from Programa Compromisso para a Ciência 2008, Portugal

Mitigation of urban heat island effects by thermochromic asphalt pavement

Asphalt road pavements are usually dark and, consequently, have a low albedo. Therefore, they absorb energy as heat, increasing the Urban Heat Island (UHI) effect, which impacts the environment, energy consumption, and human health. Through the functionalization with thermochromic materials (TM), this work aims to develop a smart asphalt pavement able to change its surface color, increasing the reflectance, and thus mitigate this phenomenon. To achieve this goal, asphalt substrates were functionalized by a surface spray coating of a thermochromic solution (TS) containing aqueous solution of thermochromic microcapsules (thermocapsules), dye, and epoxy resin. To evaluate the functionalization features, Fourier Transform Infrared Spectroscopy (FTIR), and Thermal Differential test (TDT) with cyclic temperature variation were performed in the functionalized asphalt binder. Moreover, Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectrometry (EDS), a Quick Ultraviolet Accelerated Weathering Test (QUV) with Colorimetry test, and an adaptation of the Accelerated Polishing Test (APT) were performed on the functionalized asphalt mixture. The results indicate that the functionalization of asphalt substrates with TS exhibits a reversible color-change ability, higher luminosity values when subjected to temperatures above 30 C, and wear resistance

Pavimentos rodoviários termosensitivos: funcionalização com termocápsulas para mitigação dos efeitos de ilha de calor

A coloração preta dos pavimentos rodoviários acentua a absorção de energia em forma de calor e contribui para o fenómeno de ilha de calor, que possui impactos relacionados com o ambiente, o consumo de energia e a saúde. Através da concessão de novas habilidades (funcionalização) por aspersão superficial de um revestimento contendo uma solução com corante e partículas termocromáticas (termocápsulas), cuja mudança de cor é sensível a variações de temperatura, foi possível alterar reversivelmente a cor da superfície do pavimento a partir de 30 °C e apresentar uma solução capaz de ajudar a reduzir a temperatura em meio urbano.Os autores agradecem o apoio da Fundação para a Ciência e Tecnologia (FCT), NanoAir PTDC/FISMAC/6606/2020, UIDB/04650/2020 e UIDB/04029/2020

Tinctorial behaviour of curaua and banana fibers and dyeing wastewater treatment by porous alumina membranes

Poster apresentado no "International Congress on Water, Waste and Energy Management", no Porto, Portugal 2014The ecological benefits of renewable raw materials are clear: they save valuable resources, are environmentally sound and do not cause health problems [1]. Natural fibers have already established a track record in several different areas of engineering such as, civil, automobiles, architecture among others [2]. A continued search in the utilization of certain natural fibers that would be discarded to the environment, such as from the stem of the banana tree, makes further investigations to be carried out in order to add more value to these materials [3]. Curaua, another important natural substrate, is leaf fibers extracted from an Amazon-forest plant (Ananas erectifolius) that resembles a pineapple plant. Curaua fibers have low-cost of production and offer a relatively high tensile strength level. Even though these naturals fibers are well established, for example, as reinforce in composite materials, the dyeing properties of curaua and banana fibers are not well studied yet. Thus, the dyeing process of these materials was performed with reactive conventional dyes and, after that, the effluent obtained was treated with an advanced method using membrane filtration