Coupling dechlorination and catalytic pyrolysis to produce carbon nanotubes from mixed polyvinyl chloride and polyethylene

The presence of chlorine in polyvinyl chloride (PVC) presents a major challenge for realizing the high-value utilization of real waste plastics. The objective of this research was to develop a chlorine-resistant process for the preparation of carbon nanotubes (CNTs) from mixed plastics containing PVC. This study investigates the influence of PVC content and various dechlorinating agents (CaO, Na2CO3, red mud (RM), ZSM-5, Fe-Al2O3, Fe(OH)3) on CNTs formation. The results showed that PVC content exceeding 5 % significantly inhibits CNTs formation. Employing dechlorinating agents in the pyrolysis process results in a substantial yield of CNTs from mixed plastics containing 10 % PVC. Among the dechlorinating agents, RM proves to be the most effective, leading to the highest carbon yield (at 30 wt%) and superior CNTs quality. Other dechlorinating agents, except for ZSM-5, yield comparable results, although there were some obvious variations of volatiles. Further investigation of the role of dechlorinating agents from the perspective of volatiles evolution was conducted via Py-GC/MS, and found that the dechlorination agent efficiently absorbs the HCl from mixed plastics pyrolysis, while also exhibiting catalytic and regulatory influence on volatile components. These findings offer valuable insights for the development of a chlorine-resistant process in the preparation of CNTs from mixed plastics that contain PVC.</p

IMECE2002-34587 NUMERICAL AND EXPERIMENTAL STUDY OF IMPELLER DIFFUSER INTERACTION

ABSTRACT The unsteadiness of the flow at the leading edge of a vaned diffuser represents a source of low efficiency and instability in a centrifugal turbomachine. Furthermore, the internal flow of the impeller can be affected by asymmetric downstream conditions, which results in extra flow unsteadiness and instabilities. Numerical and experimental data are obtained. The simulation of impeller diffuser interaction is performed using CFXTascflow. A frozen rotor simulation is used for the steady calculation and a rotor-stator simulation is used for the unsteady calculation using the steady results as an initial guess. The unsteady simulation is done not only for one impeller and diffuser blades, but also for the whole impeller and diffuser blades using Unix workstation. For the experimental work, a transparent fan is design and tested at The Turbomachinery Laboratory of SJTU. The test rig consists of a centrifugal, shrouded impeller, diffuser and volute casing all made of plexiglass. A particle image velocimeter (PIV) is used to measure the 2-D instantaneous velocity in the interaction region between impeller, vaned. A series of performance measurements were carried out at different speeds. The first trial of measuring the instantaneous flow field in a part of the impeller and vaned diffuser together at different relative locations between them is presented in this work at different flow rates. Obtaining detailed measurements in the interaction region between the impeller and diffuser can help in understanding the complex flow phenomena and improving centrifugal fan and compressor performance. Finally, the comparison between the unsteady measurements and unsteady calculations showed that the Rotor/Stator Model can predict the basic characteristics of unsteady flow in centrifugal fan but still need improvement to satisfy the true transient simulation for unsteady impeller diffuser interaction INTRODUCTION The improvement of machine performances can only be achieved if there is a progress in the comprehension of the nature of the complex flow that develops at the gap between rotor and stator. During the design of a turbomachine, the flow is considered steady and uniform at the entry of each element. For a centrifugal fan with a vaned diffuser, satisfying this assumption requires a large interface between the rotor and the stator so that the mixing process of the flow leaving the impeller can take place. Otherwise, the unsteady flow that enters the diffuser represents a source of low efficiency. Furthermore, the internal flow of the impeller can be affected by asymmetric downstream conditions, which results in extra flow unsteadiness and instabilities. A number of authors have treated the problem of the interaction of the impeller and its surroundings. Inoue and Cumpsty [1], Sideris [2] and Arnd

Investigation of nickel-impregnated zeolite catalysts for hydrogen/syngas production from the catalytic reforming of waste polyethylene

Catalytic steam reforming of waste high density polyethylene for the production of hydrogen/syngas has been investigated using different zeolite supported nickel catalysts in a two-stage pyrolysis-catalytic steam reforming reactor system. Experiments were conducted into the influence of the type of zeolite where Ni/ZSM5-30, Ni/β-zeolite-25 and the Ni/Y-zeolite-30 catalysts were compared in relation to hydrogen and syngas production. Results showed that the Ni/ZSM5-30 catalyst generated the maximum syngas production of 100.72 mmol g‾¹ plastic , followed by the Ni/β-zeolite-25 and Ni/Y-zeolite-30 catalyst. In addition, the ZSM-5 supported nickel catalyst showed excellent coke resistance and thermal stability. It was found that the Y type zeolite supported nickel catalyst possessed narrower pores than the other catalysts, which in turn, promoted coke deactivation of the catalyst. Large amounts of filamentous carbons were observed on the surface of the Ni/Y-zeolite-30 catalyst from scanning electron microscope images. In addition, the influence of Si:Al molar ratio for the Ni/ZSM-5 catalysts in relation to hydrogen and syngas yield was inv estigated. The results indicated that hydrogen production was less affected by the Si:Al ratio than the type of zeolite support. Also, the Ni/ZSM5-30 catalyst was further investigated to determine the influence of different process parameters on hydrogen and syngas yield via different reforming temperatures (650, 750, 850 °C) and steam feeding rate (0, 3, 6 g h‾¹). It was found that increasing both the temperature and steam feeding rate favoured hydrogen production from the pyrolysis-catalytic reforming of waste polyethylene. The optimum catalytic performance in terms of syngas production was achieved when the steam feeding rate was 6 g h‾¹ and catalyst temperature was 850 °C in the presence of Ni/ZSM5-30 catalyst, with production of 66.09 mmol H 2 g‾¹(plastic) and 34.63 mmol CO gg‾¹(plastic)

Retargeting Clostridium difficile Toxin B to Neuronal Cells as a Potential Vehicle for Cytosolic Delivery of Therapeutic Biomolecules to Treat Botulism

Botulinum neurotoxins (BoNTs) deliver a protease to neurons which can cause a flaccid paralysis called botulism. Development of botulism antidotes will require neuronal delivery of agents that inhibit or destroy the BoNT protease. Here, we investigated the potential of engineering Clostridium difficile toxin B (TcdB) as a neuronal delivery vehicle by testing two recombinant TcdB chimeras. For AGT-TcdB chimera, an alkyltransferase (AGT) was appended to the N-terminal glucosyltransferase (GT) of TcdB. Recombinant AGT-TcdB had alkyltransferase activity, and the chimera was nearly as toxic to Vero cells as wild-type TcdB, suggesting efficient cytosolic delivery of the AGT/GT fusion. For AGT-TcdB-BoNT/A-Hc, the receptor-binding domain (RBD) of TcdB was replaced by the equivalent RBD from BoNT/A (BoNT/A-Hc). AGT-TcdB-BoNT/A-Hc was >25-fold more toxic to neuronal cells and >25-fold less toxic to Vero cells than AGT-TcdB. Thus, TcdB can be engineered for cytosolic delivery of biomolecules and improved targeting of neuronal cells

The challenge and opportunity of gut microbiota‐targeted nanomedicine for colorectal cancer therapy

The gut microbiota is an integral component of the colorectal cancer (CRC) microenvironment and is intimately associated with CRC initiation, progression, and therapeutic outcomes. We reviewed recent advancements in utilizing nanotechnology for modulating gut microbiota, discussing strategies and the mechanisms underlying their design. For future nanomedicine design, we propose a 5I principle for individualized nanomedicine in CRC management

Sarcopenic Obesity and Outcomes for Patients With Cancer

Importance: The European Society for Clinical Nutrition and Metabolism (ESPEN) and the European Association for the Study of Obesity (EASO) have recently proposed a consensus definition and diagnostic criteria for sarcopenic obesity (SO). Objective: To implement the ESPEN-EASO diagnostic algorithm to investigate the prevalence of SO and its association with outcomes in patients with solid tumor cancers, with particular regard to associations among SO, overall survival (OS), and patient quality of life (QoL). Design, setting, and participants: This prospective cohort study included patients diagnosed with solid tumor starting in May 7, 2013, with the last follow-up on June 30, 2022. Patients with solid tumors were categorized into SO and non-SO groups according to ESPEN-EASO criteria. The primary outcome was OS and the secondary outcomes included patient QoL and risk of intensive care unit (ICU) admission. Data were analyzed from June to December 2023. Results: A total of 6790 patients were included in the study (mean [SD] age, 59.64 [10.77] years; 3489 were female [51.4%]). The prevalence of SO was 4.36% (296 of 6790) in the whole cohort and 14.98% (296 of 1976) in the subgroup with obesity. SO prevalence increased with age. During a median (IQR) follow-up period of 6.83 (5.67-7.04) years, 2103 patients died. Cox regression analysis indicated that SO was independently associated with lower OS (hazard ratio [HR], 1.54; 95% CI, 1.23-1.92), which was observed in both men (HR, 1.51; 95% CI, 1.09-2.10) and women (HR, 1.53; 95% CI, 1.12-2.07). SO was also associated with poorer QoL and higher risk of ICU admission (odds ratio, 2.39; 95% CI, 1.06-5.29). Among the diagnostic components of SO, low hand grip strength (HGS) was the only SO component associated with poor OS (HR, 1.15; 95% CI, 1.04-1.28). Conclusions and relevance: This cohort study of SO found that SO was significantly associated with lower OS, poorer QoL, and higher risk of ICU admission. Weak HGS, 1 of the diagnostic conditions, was the only component of SO associated with OS. The ESPEN-EASO algorithm appears to be an applicable tool to identify cancer-associated SO, which represents a major clinical complication and factor associated with risk for poor outcomes in these patients