CO2 CAPTURE FROM GASES USING ACTIVATED CARBON

Research on the CO2 adsorption on activated carbon (AC) adsorbents has gained significant interest due to their low cost, low regeneration energy, and eco-friendly characteristics. The current research was focused on the systematic development of AC using different types of biomass, pyrolysis conditions and activation conditions to prepare adsorbent with tailored textural properties for CO2 separation under simulated flue gas conditions. Impact of MgO impregnation on CO2 adsorption behavior of AC was also studied and an isothermal mass transfer model was developed to model the CO2 adsorption process in a binary mixture on porous carbon. The work was divided into four phases. The first phase of the work was focused on the synthesis of activated carbon using steam, CO2 and potassium hydroxide (KOH) as activating agents and evaluation of the CO2 adsorption performance under a range of temperature and inlet CO2 concentrations (CCO2). The KOH treated activated carbon had the best CO2 adsorption performance of 1.8 mol/kg due to its microporous structure under the optimized experimental conditions of 30 mol% CO2 and 25°C. All prepared activated carbon samples had a better performance at low temperature (~25°C) and/or high CCO2 (~30 mol%). In the second phase, the KOH activation conditions in the first phase was used for the activated carbon preparation using three different types of biomass (forest residue, agricultural residue and animal manure) as precursor and two different pyrolysis processes (fast and slow pyrolysis). The main finding in this phase was that activated carbons have different sensitivity to CO2 separation according to their micro-pore distributions; and total pore volume and surface area are not significant factors for CO2 adsorption on ACs. Overall, the pinewood saw dust derived ACs showed the best adsorption capacity of 78.1 mg/g (at 15 mol% CO2 in N2 and 25°C). In phase 3, the results of impregnating AC with magnesium oxide (MgO) showed that preparation method has a greater impact than metal content on the surface area and porosity of ACs. Moreover, MgO impregnation of AC overcomes the limitation of using not–impregnated AC at moderate temperature and low partial pressure of CO2. In the phase 4, an isothermal mass transfer model for CO2 adsorption in a mixture of CO2/N2 has been developed. The adsorption equilibrium data of CO2 on KOH activated carbon were determined at 273, 298, 323 and 348 K. The simulation of CO2 adsorption in a fixed-bed of activated carbon was performed in Python using a bi-Linear Driving Force (bi-LDF) approximation for isothermal mass transfer. The model was used to reproduce the CO2 adsorption breakthrough curves for CO2/N2 gas mixture and it can be used for designing a fixed-bed adsorption process to separate CO2 and N2 using microporous and mesoporous carbon materials

Selective CO₂ Capture by Activated Carbons: Evaluation of the Effects of Precursors and Pyrolysis Process

Activated carbons are produced from different Canadian waste biomasses including agricultural waste (wheat straw and flax straw), forest residue (sawdust and willow ring), and animal manure (poultry litter). The precursors are carbonized through the fast and slow pyrolysis processes and then activated with potassium hydroxide. A fixed-bed reactor is used for temperature swing adsorption of CO₂ in a gas mixture of N₂, O₂, and CO₂ to study the cyclic CO₂ adsorption capacity and selectivity of the produced activated carbons. The breakthrough adsorption capacity of the produced activated carbon is measured under a flue gas condition of 15 mol % of CO₂, 5 mol % of O₂, and 80% of N₂ at 25 °C and atmospheric pressure. Slow pyrolysis based activated carbon has a lower surface area and total pore volume but higher adsorption capacity in the presence of N₂. Sawdust based activated carbon synthesized using the slow pyrolysis process creates the highest ultra-micropore volume of 0.36 cm³/g, and the highest adsorption capacity in N₂ (78.1 mg/g) but low selectivity (2.8) over O₂ because of the oxygen functional groups on the surface. Ultra-micropores and surface chemistry of adsorbents are far more important than particle size, total pore volume, and internal surface area of the adsorbents. All the samples fully recovered their initial adsorption capacity in each cycle (for up to 10 cycles). This work also demonstrates that adsorption capacity and selectivity of activated carbon can be controlled and optimized through the choice of starting material and carbonization conditions

DNAH11 and a Novel Genetic Variant Associated with Situs Inversus: A Case Report and Review of the Literature

Background. Primary ciliary dyskinesia (PCD), also known as the immotile-cilia syndrome, is a clinically and genetically heterogeneous syndrome. Improper function of the cilia causes impaired mucociliary clearance. Neonatal respiratory distress, rhinosinusitis, recurrent chest infections, wet cough, and otitis media are respiratory presentations of this disease. It could also manifest as infertility in males as well as laterality defects in both sexes, such as situs abnormalities (Kartagener syndrome). During the past decade, numerous pathogenic variants in 40 genes have been identified as the causatives of primary ciliary dyskinesia. DNAH11 (dynein axonemal heavy chain 11) is a gene that is responsible for the production of cilia’s protein and encodes the outer dynein arm. Dynein heavy chains are motor proteins of the outer dynein arms and play an essential role in ciliary motility. Case Presentation. A 3-year-old boy, the offspring of consanguineous parents, was referred to the pediatric clinical immunology outpatient department with a history of recurrent respiratory tract infections and periodic fever. Furthermore, on medical examination, situs inversus was recognized. His lab results revealed elevated levels of erythrocyte sedimentation rate (ESR) and C reactive protein (CRP). Serum IgG, IgM, and IgA levels were normal, while IgE levels were elevated. Whole exome sequencing (WES) was performed for the patient. WES demonstrated a novel homozygous nonsense variant in DNAH11 (c.5247G > A; p. Trp1749Ter). Conclusion. We reported a novel homozygous nonsense variant in DNAH11 in a 3-year-old boy with primary ciliary dyskinesia. Biallelic pathogenic variants in one of the many coding genes involved in the process of ciliogenesis lead to PCD

Comprehensive assessment of respiratory complications in patients with common variable immunodeficiency

[Background] Common variable immunodeficiency (CVID) is a heterogeneous group of disorders, characterized by recurrent upper and lower respiratory tract infections and some noninfectious clinical complications.[Objective] To provide a detailed evaluation of respiratory presentations and complications in a cohort of Iranian patients with CVID.[Methods] A retrospective cohort study was conducted on 245 CVID patients who were recorded in the Iranian primary immunodeficiency disorders registry network. Respiratory manifestations were evaluated by reviewing clinical hospital records, immunologic findings, pulmonary function tests (PFT), and high-resolution computed tomography (HRCT) scans.[Results] Most of the patients (n = 208, 85.2%) had experienced at least 1 episode of acute respiratory manifestation, and pneumonia was observed in 31.6 % (n = 77) of cases as a first disease manifestation. During the follow-up, pneumonia, sinusitis, and otitis media were documented in 166 (68.6%), 125 (51.2%), and 103 (42.6%) cases, respectively. Abnormal PFT measurements were documented in 53.8% of patients. Among these patients, 21.5% showed restrictive changes, whereas 18.4% of patients showed an obstructive pattern. Bronchiectasis was the most frequent radiological finding, confirmed in 27.2% of patients. Patients with bronchiectasis were older at the time of immunodeficiency diagnosis (P < .001) and had longer diagnosis delay (P < .001) when compared with patients without bronchiectasis.[Conclusion] This study highlights the importance of monitoring the respiratory tract system even in asymptomatic patients. Pulmonary function tests and CT scans are the most commonly used techniques aiming to identify these patients early, aiming to reduce the rate of long-term respiratory complications.Funding Sources: This research was supported by the Tehran University of Medical Sciences, Tehran, Iran (grant no. 35741)

The cytoskeletal regulator HEM1 governs B cell development and prevents autoimmunity

The WAVE regulatory complex (WRC) is crucial for assembly of the peripheral branched actin network constituting one of the main drivers of eukaryotic cell migration. Here, we uncover an essential role of the hematopoietic-specific WRC component HEM1 for immune cell development. Germline-encoded HEM1 deficiency underlies an inborn error of immunity with systemic autoimmunity, at cellular level marked by WRC destabilization, reduced filamentous actin, and failure to assemble lamellipodia. Hem1−/− mice display systemic autoimmunity, phenocopying the human disease. In the absence of Hem1, B cells become deprived of extracellular stimuli necessary to maintain the strength of B cell receptor signaling at a level permissive for survival of non-autoreactive B cells. This shifts the balance of B cell fate choices toward autoreactive B cells and thus autoimmunity