21,407 research outputs found

    Using supercritical carbon dioxide for textile discoloration as part of textile recycling

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    Nowadays, textile industry poses real environment problems by its massive pollution footprint which became an imminent threat for the human being prosperity, due to: i) high greenhouse gasesÔÇÖ (GHGÔÇÖs) global emissions reasoning in energy usage and non-renewable resources exploitation; ii) increased freshwater consumption; iii) huge amounts of waste (textiles, wastewater, and chemicals) - only textile mills generate one-fifth of the worldÔÇÖs industrial water pollution and use overall 20 000 chemicals, many of them carcinogenic150; Creating socially and environmentally sustainable textile recycling loops requires a lot of effort from all industries: textile, chemicals, processing, as well as fashion, considering that nowadays less than 1% of the textile waste is recycled into products of the same value (upcycling)1. Textile recycling paradigm is complex and has some adjacent problems, such as the presence of colour in waste textile, which is treated as chemical waste, and the current textile fibre blending, i.e., mix of more than one fibre type in a single product. Therefore, this research project aims to promote a closed loop textile recycling process by using pressurized natural gas, in the form of supercritical carbon dioxide (scCO2), for colour/pigment recovery from waste textile materials prior to their recycling. The chosen materials were selected from available commercial textiles which were dyed either using wet or dry dyeing processes. A selection of most used textile fibres was made, and the most representative synthetic and natural ones were considered in this research. As such, three different PET fibres, as well as nylon, cotton and wool fibres were used. Colour extraction results were confirmed by colour yield calculated using K/S values, revealing best results for PET materials which were previously dyed with the same technology (approx. 94% colour was recovered) proving the reversibility of dyeing process in scCO2 for this fibre, being followed by a good colour recovery from PET dyed with conventional wet process (77.0% of colour was removed). Despite nylon was successfully dyed using scCO2 process (K/S value of 6.8), its discoloration was unsatisfied (only 2% colour was removed). Moreover, natural fibres registered hardly any discoloration in scCO2. Furthermore, SEM results evidenced that fibres morphology and surface do not suffer any change when exposing to scCO2 pressurization and depressurization rates. Regarding natural fibres and nylon, the efforts should be focus on the pre-treatment stage as well as in changing the paradigm of dyeing process. However, for PET fibre, the attention needs to be directed to the development of this process, since scCO2 colour extraction is possible and effective, which represents an environmental friendly process that definitely contributes to the carbon capture and utilization (CCU) policies, emphasizing a closed loop recycling process.Atualmente, a ind├║stria t├¬xtil promove s├ęrios problemas ambientais devido ├á sua enorme pegada ecol├│gica, tornando-se numa amea├ža iminente para a prosperidade do ser humano, devido a: i) elevados teores de emiss├Áes globais referentes a gases de efeito estufa, com preponder├óncia no consumo de energia e na explora├ž├úo de recursos n├úo renov├íveis; ii) excesso de consumo de ├ígua doce; iii) enormes quantidades de res├şduos (t├¬xteis, ├íguas residuais e produtos qu├şmicos) - apenas as f├íbricas t├¬xteis geram um quinto da polui├ž├úo global de ├ígua residual e utilizam globalmente 20 000 produtos qu├şmicos, muitos deles cancer├şgenos150; A cria├ž├úo de ciclos de reciclagem t├¬xtil ambientalmente sustent├íveis requer muito esfor├žo por parte de todas as ind├║strias: t├¬xtil, qu├şmica e processual, bem como a da moda, considerando que hoje menos de 1% dos res├şduos t├¬xteis s├úo reciclados em produtos do mesmo valor (upcycling)1. O paradigma da reciclagem t├¬xtil ├ę complexo e tem problemas adjacentes, como a presen├ža de cor na roupa, que ├ę tratada como um res├şduo qu├şmico na sua reciclagem, e a atual mistura de mais de um tipo de fibra num ├║nico produto t├¬xtil, designado de blending. Assim, este projeto de investiga├ž├úo visa promover um processo de reciclagem t├¬xtil closed loop atrav├ęs da utiliza├ž├úo de g├ís natural pressurizado, sob a forma de di├│xido de carbono supercr├ştico (scCO2), para a recupera├ž├úo de corantes/pigmentos de res├şduos t├¬xteis antes da sua reciclagem. Os materiais escolhidos foram selecionados a partir de produtos comerciais dispon├şveis, que foram tingidos utilizando tanto processos de tingimento a h├║mido, com ├ígua, como a seco, com scCO2. Foi feita uma sele├ž├úo das fibras t├¬xteis mais utilizadas, tendo sido consideradas as mais representativas no mercado. Como tal, foram utilizadas tr├¬s diferentes fibras de PET (Tereftalato de polietileno), bem como fibras de nylon, algod├úo e l├ú. Os resultados da extra├ž├úo de cor foram confirmados pelo c├ílculo do rendimento da cor com base nos valores K/S, revelando melhores resultados para a amostra de PETque foi previamente tingida atrav├ęs da mesma tecnologia (aprox. 94% do corante foi recuperado), comprovando a reversibilidade do processo de tingimento em scCO2 para esta fibra. De forma complementar, uma amostra de PET previamente tingida com ├ígua, obteve tamb├ęm um bom resultado, com 77.0% da cor removida pelo scCO2. Apesar de uma amostra de nylon ter sido tingida com sucesso neste meio (valor K/S de 6.8), a sua descolora├ž├úo n├úo foi satisfat├│ria (apenas 2% de cor extra├şda). Al├ęm disso, as fibras naturais registaram aproximadamente 0% de descolora├ž├úo. Adicionalemente, observou-se que a morfologia e superf├şcie das fibras n├úo sofrem qualquer altera├ž├úo ap├│s a pressuriza├ž├úo e despressuriza├ž├úo de CO2. Assim sendo, quanto ├ás fibras naturais e ao nylon, os esfor├žos devem centrar-se na fase de pr├ę-tratamento, bem como na altera├ž├úo do paradigma do processo de tingimento. No entanto, para a fibra de PET, a aten├ž├úo deve ser direcionada para o desenvolvimento deste processo, uma vez que a extra├ž├úo de corantes com scCO2 ├ę poss├şvel e eficaz, representando assim um processo ecol├│gico e que contribui definitivamente para as pol├şticas de captura e utiliza├ž├úo de carbono (CCU), enfatizando um processo de reciclagem closed loop

    Structural Characterization of Geopolymers with the Addition of Eggshell Ash

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    It is well known that geopolymers are a new group of binder materials of alumosilicate origin. Geopolymers are made by the reaction of precursor aluminosilicate materials with alkaline activator solutions. The current research relates to a low-cost and eco-friendly procedure, suitable of being implemented in two easy steps. The first step is the production of a solid phase based on fly ash (Obrenovac, Serbia) and eggshell ash as waste materials rich in calcium. The second step is alkali activating the solid phase using an alkaline activator (a mixture of NaOH and Na2SiO3) and procedures in proper laboratory conditions. Four samples with different eggshell ash content were synthesized. The concentration of used NaOH was 12 mol dmÔłĺ3. The structural properties of all investigated samples were analyzed by XRD (X-ray diffraction), DRIFT (diffuse reflectance infrared Fourier transform), SEM (scanning electron microscopy) and UV/Vis spectroscopy analysis. XRD determined the amorphous halo with the presence of quartz as the crystal phase in all of the investigated samples. These results were confirmed by DRIFT analysis. The morphology of the samples was determined by SEM analysis. UV/Vis showed that the material could be a potential adsorbent

    Development of Binder-Free Pigment Inks for Direct Inkjet Printing on Cotton Fabric without Pretreatment

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    Inkjet printing technology is widely used in the textile digital printing application today though the current technology still requires pretreatment and postwashing procedures before and after printing. Additional chemical treatment generates a large amount of wastewater and complicates the process. Among the many potential approaches for reducing chemical waste, pigments with self-dispersing capability were prepared and formulated into binder-free inkjet inks that require no pretreatment or after-washing process when printing cotton fabrics. The new self-dispersing pigment inks were tested and evaluated on cotton fabrics. The distribution of particles was between 122.2 and 188.5 nm, and inks have excellent storage capability. Printed fabricsÔÇÖ light fastness and acid/alkali resistance are about grade 5, and printed cottonÔÇÖs washing and rubbing fastness are above grade 3. The mechanism and performance of ink drops were investigated by LF-NMR and ink-drop observation methods. This work provides a possible solution for reducing wastewater in the textile industry

    Sustainable eSiC reinforced composite materials ÔÇô synthetization and characterization

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    Sustainable and light weight composite materials have received extensive attention in the application of aerospace, automotive, agriculture and marine. Synthetic SiC is expensive and harmful to the human being. Therefore, the aim of this study is to develop eSiC reinforced aluminium matrix sustainable composite material using waste rice husk with the process route of powder metallurgy. Simple and cost-effective pyrolysis process was used for the extraction of low´┐Żdensity eSiC from agricultural waste rice husk which contains a significant amount of silica. This silica was then converted in to environmentally friendly SiC (known as eSiC) material and used as a reinforcing agent to the lightweight composite development. From the results, these materials showed good metallurgical bonding with better mechanical properties. It is also observed that compared to metallic cast iron, this new composite material is better in terms of cost, material usage, eco-friendly (no harm to the environment and people), hence, sustainable. This concept demonstrates that this new sustainable and lightweight material can be used for aerospace, automotive and other structural applications, especially for disk brake, liner, and shaft. This eSiC can also be used as a coating material for composite coating development

    Microplastics in European sea salts ÔÇô An example of exposure through consumer choice and of interstudy methodological discrepancies

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    Microplastics are contaminants of emerging concern, not least due to their global presence in marine surface waters. Unsurprisingly, microplastics have been reported in salts harvested from numerous locations. We extracted microplastics from 13 European sea salts through 30% H2O2 digestion and filtration over 5-┬Ám filters. Filters were visually inspected at magnifications to x100. A subsample of potential microplastics was subjected to Raman spectroscopy. Particle mass was estimated, and human dose exposure calculated. After blank corrections, median concentrations were 466 ┬▒ 152 microplastics kg-1 ranging from 74 to 1155 items kg-1. Traditionally harvested salts contained fewer microplastics than most industrially harvested ones (t-test, p < 0.01). Approximately 14 ┬Ág of microplastics (< 12 particles) may be absorbed by the human body annually, of which a quarter may derive from a consumer choosing sea salt. We reviewed existing studies, showing that targeting different particle sizes and incomplete filtrations hinder interstudy comparison, indicating the importance of method harmonisation for future studies. Excess salt consumption is detrimental to human health; the hazardousness of ingesting microplastics on the other hand has yet to be shown. A portion of microplastics may enter sea salts through production processes rather than source materials

    Strontium-doped chromium oxide for RhB reduction and antibacterial activity with evidence of molecular docking analysis

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    The emergence of multi-drug resistance (MDR) in aquatic pathogens and the presence of cationic dyes are the leading causes of water contamination on a global scale. In this context, nanotechnology holds immense promise for utilizing various nanomaterials with catalytic and antibacterial properties. This study aimed to evaluate the catalytic and bactericidal potential of undoped and Sr-doped Cr2O3 nanostructures (NSs) synthesized through the co-precipitation method. In addition, the morphological, optical, and structural properties of the resultant NSs were also examined. The optical bandgap energy of Cr2O3 has been substantially reduced by Sr doping, as confirmed through extracted values from absorption spectra recorded by UV-Vis studies. The field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) micrographs illustrate that the composition of Cr2O3 primarily consisted of agglomerated, irregularly shaped NSs with a morphology resembling nanoflakes. Moreover, the presence of Sr in the lattice of Cr2O3 increased the roughness of the resulting NSs. The catalytic activity of synthesized NSs was analyzed by their reduction ability of Rhodamine B (RhB) dye in the dark under different pH conditions. Their antibacterial activity was evaluated against MDR Escherichia coli (E. coli). Sr doping increased antibacterial efficiency against MDR E. coli, as indicated by inhibition zone measurements of 10.15 and 11.75 mm at low and high doses, respectively. Furthermore, a molecular docking analysis was conducted to determine the binding interaction pattern between NSs and active sites in the target cell protein. The findings corroborated antimicrobial test results indicating that Sr-Cr2O3 is the most effective inhibitor of FabH and DHFR enzymes

    Hydrothermal treatment of waste plastics : an environmental impact study

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    This paper presents the attributional life cycle assessment results of a study of plastic recycling using hydrothermal treatment (HTT), a chemical recycling technology. HTT was investigated due to its potential to address current gaps in the plastic recycling system, largely due to several plastic packaging materials and formats that are currently not processed by traditional mechanical recycling technologies. As society transitions towards a net-zero-based circular economy, assessments should be conducted with a futuristic outlook, preventing costly mistakes by employing the right technologies in the right areas. The results using ReCiPe 2016 impact assessment methodology shows HTT with a GWP of 478 kg CO2 eq. per tonne can generate up to 80% reduction in climate change impacts when compared with comparable end-of-life treatment technologies whilst conserving material with the system. Additionally, the GWP could be reduced by up to 57% by changing how electricity is generated for on-site consumption. This represents a new understanding of the chemical recycling of polymers by establishing a prospective life cycle assessment study that looks to introduce a step-change in the recycling system and highlights the benefits of introducing this technology as opposed to the current model of disposal through incineration or landfill

    Examples of works to practice staccato technique in clarinet instrument

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    Klarnetin staccato tekni─čini g├╝├žlendirme a┼čamalar─▒ eser ├žal─▒┼čmalar─▒yla uygulanm─▒┼čt─▒r. Staccato ge├ži┼člerini h─▒zland─▒racak ritim ve n├╝ans ├žal─▒┼čmalar─▒na yer verilmi┼čtir. ├çal─▒┼čman─▒n en ├Ânemli amac─▒ sadece staccato ├žal─▒┼čmas─▒ de─čil parmak-dilin e┼č zamanl─▒ uyumunun hassasiyeti ├╝zerinde de durulmas─▒d─▒r. Staccato ├žal─▒┼čmalar─▒n─▒ daha verimli hale getirmek i├žin eser ├žal─▒┼čmas─▒n─▒n i├žinde et├╝t ├žal─▒┼čmas─▒na da yer verilmi┼čtir. ├çal─▒┼čmalar─▒n ├╝zerinde titizlikle durulmas─▒ staccato ├žal─▒┼čmas─▒n─▒n ilham verici etkisi ile m├╝zikal kimli─če yeni bir boyut kazand─▒rm─▒┼čt─▒r. Sekiz ├Âzg├╝n eser ├žal─▒┼čmas─▒n─▒n her a┼čamas─▒ anlat─▒lm─▒┼čt─▒r. Her a┼čaman─▒n bir sonraki performans ve tekni─či g├╝├žlendirmesi esas al─▒nm─▒┼čt─▒r. Bu ├žal─▒┼čmada staccato tekni─činin hangi alanlarda kullan─▒ld─▒─č─▒, nas─▒l sonu├žlar elde edildi─či bilgisine yer verilmi┼čtir. Notalar─▒n parmak ve dil uyumu ile nas─▒l ┼čekillenece─či ve nas─▒l bir ├žal─▒┼čma disiplini i├žinde ger├žekle┼čece─či planlanm─▒┼čt─▒r. Kam─▒┼č-nota-diyafram-parmak-dil-n├╝ans ve disiplin kavramlar─▒n─▒n staccato tekni─činde ayr─▒lmaz bir b├╝t├╝n oldu─ču saptanm─▒┼čt─▒r. Ara┼čt─▒rmada literat├╝r taramas─▒ yap─▒larak staccato ile ilgili ├žal─▒┼čmalar taranm─▒┼čt─▒r. Tarama sonucunda klarnet tekni─čin de kullan─▒lan staccato eser ├žal─▒┼čmas─▒n─▒n az oldu─ču tespit edilmi┼čtir. Metot taramas─▒nda da et├╝t ├žal─▒┼čmas─▒n─▒n daha ├žok oldu─ču saptanm─▒┼čt─▒r. B├Âylelikle klarnetin staccato tekni─čini h─▒zland─▒rma ve g├╝├žlendirme ├žal─▒┼čmalar─▒ sunulmu┼čtur. Staccato et├╝t ├žal─▒┼čmalar─▒ yap─▒l─▒rken, araya eser ├žal─▒┼čmas─▒n─▒n girmesi beyni rahatlatt─▒─č─▒ ve isteklili─či daha artt─▒rd─▒─č─▒ g├Âzlemlenmi┼čtir. Staccato ├žal─▒┼čmas─▒n─▒ yaparken do─čru bir kam─▒┼č se├žimi ├╝zerinde de durulmu┼čtur. Staccato tekni─čini do─čru ├žal─▒┼čmak i├žin do─čru bir kam─▒┼č─▒n dil h─▒z─▒n─▒ artt─▒rd─▒─č─▒ saptanm─▒┼čt─▒r. Do─čru bir kam─▒┼č se├žimi kam─▒┼čtan rahat ses ├ž─▒kmas─▒na ba─čl─▒d─▒r. Kam─▒┼č, dil atma g├╝c├╝n├╝ vermiyorsa daha do─čru bir kam─▒┼č se├žiminin yap─▒lmas─▒ gereklili─či vurgulanm─▒┼čt─▒r. Staccato ├žal─▒┼čmalar─▒nda ba┼čtan sona bir eseri yorumlamak zor olabilir. Bu a├ž─▒dan ├žal─▒┼čma, verilen m├╝zikal n├╝anslara uyman─▒n, dil at─▒┼č performans─▒n─▒ rahatlatt─▒─č─▒n─▒ ortaya koymu┼čtur. Gelecek nesillere edinilen bilgi ve birikimlerin aktar─▒lmas─▒ ve geli┼čtirici olmas─▒ te┼čvik edilmi┼čtir. ├ç─▒kacak eserlerin nas─▒l ├ž├Âz├╝lece─či, staccato tekni─činin nas─▒l ├╝stesinden gelinebilece─či anlat─▒lm─▒┼čt─▒r. Staccato tekni─činin daha k─▒sa s├╝rede ├ž├Âz├╝me kavu┼čturulmas─▒ ama├ž edinilmi┼čtir. Parmaklar─▒n yerlerini ├Â─čretti─čimiz kadar belle─čimize de ├žal─▒┼čmalar─▒n kaydedilmesi ├Ânemlidir. G├Âsterilen azmin ve sabr─▒n sonucu olarak ortaya ├ž─▒kan yap─▒t ba┼čar─▒y─▒ daha da yukar─▒ seviyelere ├ž─▒karacakt─▒r
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