Bio-reinforced self-healing concrete using magnetic iron oxide nanoparticles
- Authors: Seifan, Mostafa , Sarmah, Ajit , Ebrahiminezhad, Alireza , Ghasemi, Younes , Samani, Ali Khajeh , Berenjian, Aydin
- Date: 2018
- Type: Text , Journal article
- Relation: Applied Microbiology and Biotechnology Vol. 102, no. 5 (2018), p. 2167-2178
- Full Text: false
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- Description: Immobilization has been reported as an efficient technique to address the bacterial vulnerability for application in bio self-healing concrete. In this study, for the first time, magnetic iron oxide nanoparticles (IONs) are being practically employed as the protective vehicle for bacteria to evaluate the self-healing performance in concrete environment. Magnetic IONs were successfully synthesized and characterized using different techniques. The scanning electron microscope (SEM) images show the efficient adsorption of nanoparticles to the Bacillus cells. Microscopic observation illustrates that the incorporation of the immobilized bacteria in the concrete matrix resulted in a significant crack healing behavior, while the control specimen had no healing characteristics. Analysis of bio-precipitates revealed that the induced minerals in the cracks were calcium carbonate. The effect of magnetic immobilized cells on the concrete water absorption showed that the concrete specimens supplemented with decorated bacteria with IONs had a higher resistance to water penetration. The initial and secondary water absorption rates in bio-concrete specimens were 26% and 22% lower than the control specimens. Due to the compatible behavior of IONs with the concrete compositions, the results of this study proved the potential application of IONs for developing a new generation of bio self-healing concrete.
Mechanical properties of bio self-healing concrete containing immobilized bacteria with iron oxide nanoparticles
- Authors: Seifan, Mostafa , Sarmah, Ajit , Samani, Ali Khajeh , Ebrahiminezhad, Alireza , Ghasemi, Younes , Berenjian, Aydin
- Date: 2018
- Type: Text , Journal article
- Relation: Applied Microbiology and Biotechnology Vol. 102, no. 10 (2018), p. 4489-4498
- Full Text: false
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- Description: Concrete is arguably one of the most important and widely used materials in the world, responsible for the majority of the industrial revolution due to its unique properties. However, it is susceptible to cracking under internal and external stresses. The generated cracks result in a significant reduction in the concrete lifespan and an increase in maintenance and repair costs. In recent years, the implementation of bacterial-based healing agent in the concrete matrix has emerged as one of the most promising approaches to address the concrete cracking issue. However, the bacterial cells need to be protected from the high pH content of concrete as well as the exerted shear forces during preparation and hardening stages. To address these issues, we propose the magnetic immobilization of bacteria with iron oxide nanoparticles (IONs). In the present study, the effect of the designed bio-agent on mechanical properties of concrete (compressive strength and drying shrinkage) is investigated. The results indicate that the addition of immobilized Bacillus species with IONs in concrete matrix contributes to increasing the compressive strength. Moreover, the precipitates in the bio-concrete specimen were characterized using scanning electron microscope (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDS). The characterization studies confirm that the precipitated crystals in bio-concrete specimen were CaCO3, while no precipitation was observed in the control sample.
Exploring greener pathways and catalytic systems for ethylene carbonate production
- Authors: Ng, Wei , Minh Loy, Adrian , McManus, David , Gupta, Ashwani , Sarmah, Ajit , Bhattacharya, Sankar
- Date: 2023
- Type: Text , Journal article , Review
- Relation: ACS Sustainable Chemistry and Engineering Vol. 11, no. 39 (2023), p. 14287-14307
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- Description: The production of cyclic carbonates is pivotal in carbon capture and utilization (CCU), providing an opportunity to utilize recycled CO2. Ethylene carbonate (EC) holds significance among cyclic carbonates in industrial settings due to its extensive applications in lithium-ion batteries and industrial lubricants and as a precursor for green polycarbonate production. However, the current synthesis of EC relies on toxic, fossil-based epoxide reactants, which poses sustainability challenges. To meet the growing demand for green chemistry, three greener alternative pathways for EC synthesis have been proposed, involving the reaction of carbon-based reactants (CO2, urea, and dimethyl carbonate) with ethylene glycol (EG) derived from biodiesel waste. This Perspective addresses key inquiries surrounding alternative EC synthesis pathways through quantitative and qualitative assessments. Specifically, we elucidate (a) possible sustainable routes, (b) current advances in the first principle of kinetic and operational methods, and (c) differences in reactions from the perspectives of thermodynamics, safety, and greenness of production. Notably, the direct carboxylation of CO2 with EG emerges as a promising green synthesis route, but challenges persist, such as catalyst development and water inhibition. Finally, future prospects for overcoming challenges in the green manufacturing of EC are discussed, providing insights into advancing CCU. © 2023 American Chemical Society.