9 research outputs found
RECOVERY AND SEPARATION PROCESSES IN THE RECYCLING CHAIN OF POLYAMIDE PLASTIC MATERIALS TO OBTAINECO-SUSTAINABLE RAW MATERIALS
No full textThe rise of fast fashion and the growing accumulation of mixed textile and plastic waste are creating serious environmental and economic challenges. In particular, polyamides, commonly used in technical textiles and plastics, are often blended with other polymers, making recycling difficult. Traditional methods such as mechanical processing or depolymerization often fail when dealing with these complex mixtures, due to degradation, contamination, or the need for extensive purification. This PhD research, carried out in collaboration with Radici InNova s.c.a r.l. (Radici Group), focused on developing and optimizing a solvent-based recycling process to selectively recover polyamide from post-industrial and post-consumer textile and plastic waste.
The process, known as selective dissolution, involves the use of a specific solvent or solvent mixture to dissolve only the target polymer (polyamide) from a complex material. The other components, such as polyurethane or polyester, remain undissolved and are removed by filtration. The dissolved polyamide is then recovered from the solution by changing the solvent conditions (for example, by adding water as an anti-solvent or by evaporating the solvent), allowing the polymer to re-precipitate in a purified form.
Two solvent systems (solvents A and B) were selected for in-depth study based on a literature review and preliminary experimental screening. These solvents were chosen for their ability to dissolve PA while maintaining selectivity over other polymers. Experimental work showed that both solvents were effective, but solvent B allowed better separation, reducing contamination and preserving the possibility to reuse PU. Moreover, by adjusting the composition of the solvent mixture, it was possible to tune the selectivity of the process, either favouring the dissolution of polyamide or the extraction of polyurethane. This tunable selectivity was demonstrated through systematic tests on PA6, PA66, and PU fibers, using controlled solvent B/water ratios and analysing the dissolution temperatures of each sample. The solubility behaviour was mapped in relation to solvent composition, helping to define process windows for each target polymer. Different types of waste were tested.
Various methods were tested to recover PA from the solution, including anti-solvent crystallization, direct evaporation, and spray drying. Anti-solvent precipitation produced a purer polyamide, with limited molecular degradation and mechanical properties comparable to those required for textile applications. Evaporation resulted higher polymer degradation and in a more flexible materials, likely due to the presence of residual low-molecular-weight compounds acting as plasticizers. Spray drying offered rapid solvent removal but posed challenges in terms of polymer degradation and system clogging, especially with PA-rich solutions.
All samples were extensively characterized to assess their chemical integrity and applicability: intrinsic viscosity, end-group analysis (–NH2 and –COOH), infrared spectroscopy, and differential scanning calorimetry (DSC) were used to determine degradation and purity. In selected cases, the recovered PA was also tested for mechanical performance through tensile strength and impact resistance measurements on injection-moulded specimens, without blending with virgin polymer. The results confirmed that the recycled PA showed good performance.
Special attention was given to solvent recovery, which is essential for the environmental and economic sustainability of the process. For the water–solvent A mixture, both simple and multi-stage distillation were tested, showing good efficiency and the possibility of solvent reuse. Both the impurities accumulating in the reboiler and in the distillate were characterized by GC-MS and TOC analyses. Tests were also carried out to evaluate both the direct reuse of the distillation bottom and the complete purification of the glycol through total solvent evaporation. For solvent B, azeotropic distillation using an entrainer was developed to improve separation and reduce losses. Process simulations using AVEVA Pro/II helped design the distillation systems and confirm the experimental results, especially in terms of tray number, reflux ratio, and entrainer recovery. The use of azeotropic distillation proved advantageous over traditional binary separation, both in terms of energy consumption and solvent purity.
Finally, a Life Cycle Assessment (LCA) was conducted to evaluate the environmental performance of the process. Two process options were compared: anti-solvent precipitation and direct evaporation. Both showed much lower impacts than virgin PA production, with the evaporation route performing slightly better in most categories. The potential reuse of polyurethane and the efficient solvent recovery helped improve the overall sustainability. Contribution analysis highlighted the influence of steam consumption and solvent losses, underlining the importance of process optimization for full-scale implementation.
This research shows that selective dissolution is a promising method for recycling nylon-based textiles and plastics. It allows recovery of high-quality PA and offers a feasible path towards more circular and sustainable production. A patent application has been filed, and scale-up activities are currently underway, including pilot plant development studies and additional research on solvent recovery under the RE-POLY.AI project
Shaping the empty carbon nanocubes: the role of Nitrogen. Insight from X-Ray Raman scattering spectroscopy at the N K-edge
No full textCarbon nanomaterials have gained significant attention because of their unique tunable properties, including high surface area, excellent electrical conductivity, and chemical stability. These materials are classified by dimension, including 0D carbon quantum dots, 1D nanofibers, 2D nanosheets, and 3D hierarchical nanostructures such as hollow nanocages. Hollow carbon nanocages exhibit distinct characteristics, such as interior cavities and subnanometer channels, which enhance their structural stability and electrocatalytic efficiency. Furthermore, these structures, particularly when doped with heteroatoms like nitrogen, offer promising applications in energy storage, conversion, and sensing technologies. Nitrogen doping significantly influences the electronic properties, creating additional energy levels and active catalytic sites. Doping also facilitates extreme bending of the graphene planes, which improves electrocatalytic performance by enhancing oxygen reduction reactions and increasing active site density. This paper demonstrates, through both experimental and theoretical methods, that nitrogen atoms preferentially accumulate at the edges of carbon nanocages, inducing curvature in the graphitic structure. This finding provides insight into how heteroatom doping can be leveraged to tune the structural and electrochemical properties of carbon nanomaterials for advanced applications
Nylon Recycling Processes: a Brief Overview
No full textPlastic pollution is a significant environmental issue, and recycling has been identified as one of the ways to reduce its impact. This review provides therefore a brief overview of the various processes involved in recycling of polyamide plastic waste. Nylon is a material extensively utilized in the creation of clothes, textiles, and other products thanks to its high mechanical and thermal properties, as well as its strength and durability. This latter feature turns in a very slow decomposition if polyamide-based objects are abandoned in the environment, making it a significant environmental pollutant. The review covers all the possible recycling processes for this material, that are mechanical recycling, which involves shredding and melting plastic waste to make new products, solvent dissolution, where a solvent selectively dissolved only the desired polymer leaving behind the unwanted impurities, and chemical recycling, which uses chemical reactions to break down plastic waste into its chemical constituent parts, i.e. Monomers. The advantages and limitations of these processes are discussed
Polyamide recycling by selective dissolution approach: Life Cycle Assessment study and environmental impacts comparison with different recycling technologies
No full textPolyamide 6 (PA6) is a material extensively utilized thanks to its high mechanical and thermal properties, but its widespread use has raised concerns about its environmental impact, especially because polyamides are often coupled with other materials that hinder recyclability. Recycling techniques currently at industrial scale are mechanical and chemical recycling, but the high temperatures and harsh chemicals involved generate impurities that complicate the process, leading the waste materials to disposal. Solvent-based recycling may offer a solution allowing non-nylon-coupled material separation at milder process conditions, but no industrial data and few studies concerning its environmental impacts are available. This work reports the Life Cycle Assessment of polyamide selective dissolution recycling, analyzing different process configuration scenarios, where the precipitation of PA6 is induced either by the addition of an antisolvent or by solvent evaporation, also exploring the possibility to valorize the non-nylon-coupled material. A comparison between mechanical, chemical, and solvent-based recycling is made in terms of applicability and environmental impacts, all calculated considering renewable energy sources. Solvent-based recycling approach from an environmental point of view resulted as industrially feasible, where best environmental performing process configuration results in solvent evaporation-induced PA6 precipitation, with a global warming potential between chemical and mechanical recycling. Highlights: Dissolution recycling is an innovative process to treat mixed plastic waste. Life Cycle Assessment (LCA) analysis is useful to evaluate the industrial feasibility of a new process. LCA of dissolution recycling considering different configurations was evaluated. Comparative LCA analysis of current PA6 recycling methods with solvent-based one. Dissolution recycling can be considered a valid alternative for PA6 recycling
Determination of vapour pressures of FAME industrial mixtures by ebullioscopic and thermogravimetric experimental methods
No full textVapour pressure (VP) is a parameter that characterizes, by principle, only pure compounds. Nevertheless, it can refer also to mixtures in order to characterize their volatility or to be inserted in technical documents. The measurement of VP for mixtures is strongly dependent on the possible variation of the composition, during experiments, due to the different volatility of the constituent compounds. It is possible to calculate the VP of the mixture starting from its composition, but different thermodynamic scenarios must be considered. Moreover, for industrial samples, possible effects due to the presence of impurities must be considered. In this work, two different experimental methods have been employed to determine VP of some acetates esters and two industrial mixtures of fatty acid methyl esters (FAME). The first method is a direct ebullioscopic method, while the second is an indirect thermogravimetric analysis (TGA). An error function was calculated to compare the experimental results of VPs obtained with the two methodologies with the theoretical ones. Ebullioscopic measures resulted suitable only for acetates esters, as FAME mixtures are characterized by VPs too low to be quantified with this technique. On the contrary, TGA methodology is more accurate for FAME than acetates. It allows the collection of a great number of VP values with a very fast analysis. This method is less accurate than others, but it can be useful for a fast screening of the FAME mixtures, also contaminated with light impurities
Simulated-Experimental Cross Validation of Multistage Batch Distillation for Water/Propylene Glycol Separation as Educational Exercise
No full textThis study describes an educational exercise concerning the multistage batch distillation of the mixture water-propylen glycol (PG). The research study consisted of three primary components: practical experimentation using a batch distillation setup, computer simulations, utilizing the AVEVA PRO/IITM software, and the development and operation of a multistage system. The initial experiment was centred around the process of distillation involving mixtures of n-heptane/toluene and water/PG. This phase aimed to establish a fundamental understanding that would be crucial for conducting further simulations using the AVEVA PRO/IITM platform. The utilisation of these simulations is the basic background in customizing the design and optimizing the performance parameters of the multistage distillation plant, hence guaranteeing the highest possible level of separation efficiency
Hydrogen Purification and Odorization to Evaluate the Distribution of This Energy Carrier Through the Gas Pipelines
No full textDue to hydrogen storage and transport problem, a concrete and immediate solution is the exploitation of the gas pipelines now used for natural gas. In this regard, this work aims to evaluate two main aspects that must be taken into account to make this approach possible: the separation of hydrogen from natural gas-hydrogen mixture and the odorization of the latter, in order to provide the safety of the pipelines. Therefore, the first part of this study is the evaluation of the efficiency of a purification system in presence of a variable quantity of methane in the inner stream. For these purposes, electrochemical hydrogen compression (EHC) system was selected, due to the great advantage of allowing both purification and compression in a single device. Different methane-hydrogen mixtures were taken into consideration, going to evaluate how an increasing amount of methane affects the efficiency of the system. The second part of this work is focused on a further development of a previous simulation study related to a possible process for natural gas-hydrogen mixtures odorization systems using AVEVA's PRO II software. As odorant, GASODOR S-FREE was taken into consideration, thanks to the fact that this is a common odorant used for methane with the great advantage of not containing sulfur, unlike THT and mercaptans
Study of Different H2/CO2 Ratios as Feed in Fischer-Tropsch Reactor with Iron-Based Nano-Hydrotalcite Catalysts
No full textCO2-FTS is among the most viable methods for converting CO2 into useful chemicals and fuels in order to minimize CO2 emissions. Due to its chemical inertness, however, effective conversion continues to be a difficulty. The challenges in terms of yield and mechanism have attracted the interest of different research groups in the development of a new carbon dioxide hydrogenation catalysts, capable of reaching satisfactory results. In this work, a selection of nano ternary hydrotalcites (HTlc) were synthesized with and without ultrasound in order to develop active Fe-based catalysts for the Fischer–Tropsch synthesis. HTlc consists mostly of metal hydroxides in which different metal atoms are uniformly distributed at the atomic level. The reaction was carried in a lab scale plant in a fixed bed configuration. All fresh and used catalysts were examined and characterized using XRPD, ICP-OES, SEM, TEM, BET. Ternary HTlc composed of Mg, Cu, and Fe was synthesized using an ultrasound-assisted co-precipitation technique (MCF-US). HTlc was tested for carbon dioxide hydrogenation reaction with a study concerning different H2/CO2 ratios in order to evaluate the product distribution as well as the efficiency of the catalyst itself. The CO2 conversion resulted higher and more stable in feeds with higher H2 quantities. The selectivity towards higher chain hydrocarbons was higher for lower H2/CO2 ratios whereas methane and carbon monoxide selectivities were adequately low
Generalized infection with unknown starting point in children hospitalized in a district hospital
No full textJankowska Paula, Jankowski Krzysztof, Kamiński Piotr, Rudnicka-Drożak Ewa. Generalized infection with unknown starting point in children hospitalized in a district hospital. Journal of Education, Health and Sport. 2019;9(7):742-747. eISSN 2391-8306. DOI http://dx.doi.org/10.5281/zenodo.3357156
http://ojs.ukw.edu.pl/index.php/johs/article/view/7200
The journal has had 7 points in Ministry of Science and Higher Education parametric evaluation. Part B item 1223 (26/01/2017).
1223 Journal of Education, Health and Sport eISSN 2391-8306 7
© The Authors 2019;
This article is published with open access at Licensee Open Journal Systems of Kazimierz Wielki University in Bydgoszcz, Poland
Open Access. This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author (s) and source are credited. This is an open access article licensed under the terms of the Creative Commons Attribution Non commercial license Share alike.
(http://creativecommons.org/licenses/by-nc-sa/4.0/) which permits unrestricted, non commercial use, distribution and reproduction in any medium, provided the work is properly cited.
The authors declare that there is no conflict of interests regarding the publication of this paper.
Received: 01.07.2019. Revised: 05.07.2019. Accepted: 01.08.2019.
Generalized infection with unknown starting point in children hospitalized in a district hospital
Paula Jankowska1, Krzysztof Jankowski1, Piotr Kamiński2, Ewa Rudnicka-Drożak1
1. Chair and Department of Family Medicine, Medical University of Lublin
2. Chair and Department of Trauma Surgery and Emergency Medicine, Medical University of Lublin
ABSTRACT
Introduction
Infection is the most common cause of children medical consultations. Often the clinical picture of the patient is disproportionate to the results of laboratory tests which may indicate for generalized infection.
Case reports
Case 1: A 4-year-old patient admitted to the Department due to a fever 39˚C lasting from 2 days and periodic abdominal pain. Good general condition, throat slightly red. In laboratory studies, procalcitonin 44.5 ng/ml, CRP 121.5 mg/dl, WBC 15.32 ths/ul. Empirical treatment with ceftriaxone and vancomycin was included. Blood cultures, Staphylococcus hominis MLSB, MRCNS.
Case 2: A patient nearly 5 years old admitted to the Department due to a fever 39.5˚C. In outpatient examinations CRP 41 mg/dl, WBC 39 ths/ul. Physical examination: reddening of throat mucosa, palatine tonsils slightly enlarged, reddish, without rash. In laboratory tests CRP 95 mg/dl, WBC 41.95 ths/ul, PCT 1.19 ng/ml. On the second day of hospitalization, an increase in inflammatory markers was observed (PCT 1.47 ng/ml, CRP 235.7 mg/dl). Vancomycin was added.
Case3: 18-month-old boy admitted to the Department due to fever 40.5˚C. Good general condition, throat slightly reddened, occasional cough. In laboratory tests PCT 8.07 ng/ml. Empirical antibiotic therapy with ceftriaxone was implemented. Due to persistence of fever up to 39.5˚C - control tests of PCT 10.03 ng / ml. Vancomycin was implemented. Urine culture negative, in blood culture the present growth of Staphylococcus warneri.
Conclusions
It is extremely important to be vigilant in case of feverish children. Sometimes, despite a good general condition and no significant abnormalities in a physical examination, we can deal with generalized infection.
Keywords: Infection, Children, Pharyngeal Tonsi
