Effects of cotton textile waste properties on recycled fibre quality

WOS: 000466249500004The market for recycled cotton appears to be growing; however the main obstacle for cotton recycling is the lower quality of the resultant products. Therefore, detailed investigation of recycled cotton processes from separation/shredding to finishing is of great importance. This contribution reveals the effects of the type of cotton based textile wastes on recycled fibre properties after shredding. For this purpose, pre-consumer knitted cotton textile wastes were collected in a systematic way and sorted according to fabric tightness (loose/single-jersey and tight/interlock) and previous finishing treatments (untreated greige cotton fabrics and dyed cotton fabrics). The effect of the size of the waste fabric pieces fed to shredding was also investigated. Waste ratio of recycled fibres, recycled fibre length, spinnability of recycled cotton fibres and properties of produced yarns were tested. Results showed that lower waste ratio of recycled fibres and higher yarn breaking strength values was obtained by the recycling of cotton fibres from wastes composed of single-jersey greige cotton fabrics. In general recycled cotton fibres from dyed fabrics showed lower quality values. As a conclusion, it was indicated that better values for resultant material could be achieved by the selection of loosely knitted greige cotton fabrics. (C) 2019 Elsevier Ltd. All rights reserved.Scientific and Technical Research Council of Turkey (TUBITAK) - TEYDEBTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [9140051, E!9153]Financial support from The Scientific and Technical Research Council of Turkey (TUBITAK) -TEYDEB (No:9140051) for EUREKA E!9153 project is gratefully acknowledged

Thin film composite polyamide membrane on polydopamine layer containing stabilized particles for reverse osmosis

Ultrathin, crosslinked, aromatic polyamide (PA) thin film composite (TFC) membranes, which are interfacially polymerized onto microporous polysulfone support membranes, are extensively utilized in the state of the art reverse osmosis systems. The dense, ultrathin, crosslinked PA layer enables high water permeability with high selectivity. However, the performance of these membranes in desalination applications is currently limited by an “upper bound”, the permeability/selectivity trade off inherent in polymeric membranes and polyamide membranes are susceptible to damage from biological fouling and free chlorine. Therefore, to break through the performance upper bound of polymeric membranes, a class of mixed matrix membranes called thin film nanocomposite (TFN) membranes has been developed. In these membranes, fillers (typically inorganic nanoparticles) are dispersed in aqueous or organic phase casting solutions during interfacial polymerization process. The addition of nanoparticles to TFC membranes is a promising technology to reduce energy costs and increase the performance in desalination processes. Nevertheless, there may be some “non-ideal effects” in the membrane such as particle aggregation at higher zeolite loadings and void or rigidified polymer formation at the polymer/particle interface. Furthermore, there might be particle loss under high pressure during cross-flow desalination process which may decrease the membrane performance. In addition to the performance improvement efforts, researchers have developed thin film composite membranes functionalized with surface coating to enhance the antifouling resistance of membranes. However, due to addition of transport layer into structure, the membrane may have lower water permeability. To overcome these drawbacks, our overall goal is to develop highly permeable, antifouling thin film composite membranes with polydopamine/molecular sieve layer and anti-fouling surface coatings. The performance of these novel membranes’ will be demonstrated by desalination through reverse osmosis processes. To achieve this goal, our first research objective is to develop highly permeable polydopamine-molecular sieve/polyamide membranes without antifouling coating, which will be added later. Therefore, we developed a method to enhance membrane performance and filler particle stability in TFN membranes. First, we stabilized particles on microporous polysulfone support by thin bio-inspired polydopamine layer, and then we interfacially synthesized polyamide on top of this layer. This method also minimizes the expensive particle usage compared with the common TFN synthesis procedure (particle addition into polyamide casting solution). In this work, we present our results for development of thin film composite polyamide membranes on polydopamine layer with molecular sieves particles on polysulfone support membrane. First, we synthesized dopamine layer with different particle content and different particle size. Then, we synthesized a series of polyamide membranes via interfacial polymerization. For comparison, we also synthesized regular TFC and TFN polyamide membranes. Then we measured the permeability and selectivity performance using dead-end filtration and cross-flow testing system. We report the synthesized membrane surface and morphology result with contact angle, Fourier transform infrared spectroscopy, scanning electron microscopy, and atomic force microscopy

Threshold-Responsive Colorimetric Sensing System for the Continuous Monitoring of Gases

Colorimetric sensors are widely used because of their inherent advantages including accuracy, rapid response, ease-of-use, and low costs; however, they usually lack reusability, which precludes the continuous use of a single sensor. We have developed a threshold-responsive colorimetric system that enables repeated analyte measurements by a single colorimetric sensor. The threshold responsive algorithm automatically adjusts the sensor exposure time to the analyte and measurement frequency according to the sensor response. The system registers the colorimetric sensor signal change rate, prevents the colorimetric sensor from reaching saturation, and allows the sensor to fully regenerate before the next measurement is started. The system also addresses issues common to colorimetric sensors, including the response time and range of detection. We demonstrate the benefits and feasibility of this novel system, using colorimetric sensors for ammonia and carbon dioxide gases for continuous monitoring of up to (at least) 60 detection cycles without signs of analytical performance degradation of the sensors

COVID-19 Disease in Presenting to the Pediatric Emergency Department: A Multicenter Study of 8886 Cases.

Background: The aim was to evaluate the epidemiological, clinical, laboratory, and radiologic data of children with SARS-CoV-2 positivity by polymerase chain reaction (PCR) together with treatment strategies and clinical out-comes and to evaluate cases of multisystem inflammatory syndrome in children (MIS-C) in this population.Methods: This was a multicenter retrospective observational cohort study performed in the pediatric emergency departments of 19 tertiary hospitals. From March 11, 2020, to May 31, 2021, children who were diagnosed with confirmed nasopharyngeal/tracheal specimen SARS-CoV-2 PCR positivity or positivity for serum-specific anti-bodies against SARS-CoV-2 were included. Demographics, presence of chronic illness, symptoms, history of con-tact with SARS-CoV-2 PCR-positive individuals, laboratory and radiologic investigations, clinical severity, hospital admissions, and prognosis were recorded.Results: A total of 8886 cases were included. While 8799 (99.0%) cases resulted in a diagnosis of SARS-CoV-2 with PCR positivity, 87 (1.0%) patients were diagnosed with MIS-C. Among SARS-CoV-2 PCR-positive patients, 51.0% were male and 8.5% had chronic illnesses. The median age was 11.6 years (IQR: 5.0-15.4) and 737 (8.4%) patients were aged <1 year. Of the patients, 15.5% were asymptomatic. The most common symptoms were fever (48.5%) and cough (30.7%) for all age groups. There was a decrease in the rate of fever as age increased (p < 0.001); the most common age group for this symptom was <1 year with the rate of 69.6%. There was known contact with a SARS-CoV-2 PCR-positive individual in 67.3% of the cases, with household contacts in 71.3% of those cases. In terms of clinical severity, 83 (0.9%) patients were in the severe-critical group. There was hospital admission in 1269 (14.4%) cases, with 106 (1.2%) of those patients being admitted to the pediatric intensive care unit (PICU). Among patients with MIS-C, 60.9% were male and the median age was 6.4 years (IQR: 3.9-10.4). Twelve (13.7%) patients presented with shock. There was hospital admission in 89.7% of these cases, with 29.9% of the patients with MIS-C being admitted to the PICU.Conclusion: Most SARS-CoV-2 PCR-positive patients presented with a mild clinical course. Although rare, MIS-C emerges as a serious consequence with frequent PICU admission. Further understanding of the characteristics of COVID-19 disease could provide insights and guide the development of therapeutic strategies for target groups.(c) 2022 Elsevier Inc. All rights reserved