100 research outputs found
Bio-mediated Synthesis of Nanomaterials for Packaging Applications
Full text linkChange in lifestyle of humans in this present generation with huge dependence on packaging materials has encouraged several studies on development of new variety of packaging materials. Emphasis on replacement of existing non-biodegradable packaging materials with biodegradable materials paved the way for the use of biopolymers. Lack of properties, such as thermal stability and mechanical strength in biopolymers led to the development of bio-polymer nano-composites by adding metal/metal oxide nanoparticles as fillers into the biopolymers. Metal/metal oxide nano-particles improve mechanical/tensile strength, thermal stability as well as antimicrobial properties of the binding and receiving polymer matrix. Bio-mediated synthesis of metal/metal oxide nanoparticles result to development of novel packaging materials at a low cost and without releasing hazardous wastes into the environments. Novel packaging materials with metal/metal oxide nanoparticles as additives are capable of increasing the shelf life of food stuffs, in certain cases they act as indicators of quality food inside the package. Summarily, this present chapter focuses on bio-mediated synthesis of various metal/metal oxide nano-particles and their applications in food packaging
A panoramic view of motherhood by juxtaposing the select trilogies of Flora Nwapa and Perumal Murugan
Full text link<p>This article by Vimala Johnshi Rani compares the portrayal of motherhood in the works of African writer Flora Nwapa and Indian writer Perumal Murugan. By examining trilogies by each author, Rani explores how women in post-colonial South Africa and India navigate societal expectations and personal desires.</p>
Ammonium removal and recovery from wastewater with porous geopolymers
Full text linkAbstract
Porous geopolymer granules are emerging as a promising material for high-value applications such as adsorption and ammonium (NH₄⁺) recovery from wastewater. This thesis presents a comprehensive investigation into the fabrication, characterization, and application of porous metakaolin-based geopolymer granules produced via direct foaming, one-part alkali activation, and high-shear granulation. Porosity was introduced using either hydrogen peroxide (H₂O₂) or municipal solid waste incineration fly ash containing metallic aluminum (Al0) as blowing agents. Increased porosity, particularly in the micro- and nanoscale range, significantly enhanced the specific surface area and NH₄⁺ adsorption capacity—up to 126% higher compared to nonporous granules, with optimal performance observed using 10% H₂O₂ solution. The granules demonstrated sufficient mechanical strength (≥2 MPa) and were evaluated for environmental safety and ion-exchange behavior. While fly ash improved porosity, it introduced leaching concerns for elements like antimony and vanadium, limiting its optimal content to 0.3 wt.% Al0. Adsorption-desorption studies showed that porous geopolymer granules achieved an average NH₄⁺ uptake capacity of up to 9.0 mg/g, and NH₄⁺ recovery of 51–98% over the 30 adsorption and desorption cycles using KNO₃ as a regenerant, though performance declined after 20 cycles. Application in municipal wastewater highlighted the need for pretreatment to mitigate pore blocking and surface fouling. Overall, these findings establish porous geopolymer granules as a feasible, regenerable, and effective material for NH₄⁺ recovery, contributing to circular nitrogen economy and sustainable wastewater treatment strategies. Original papers Yu, Y., Perumal, P., Corfe, I. J., Paul, T., Illikainen, M., & Luukkonen, T. (2023). Combined granulation–alkali activation–direct foaming process: A novel route to porous geopolymer granules with enhanced adsorption properties. Materials & Design, 227, 111781. https://doi.org/10.1016/j.matdes.2023.111781 https://doi.org/10.1016/j.matdes.2023.111781 Self-archived version Luukkonen, T., Yu, Y., Adhikary, S. K., Kauppinen, S., Finnilä, M., & Perumal, P. (2024). Metallic aluminium in municipal solid waste incineration fly ash as a blowing agent for porous alkali-activated granules. Royal Society Open Science, 11(8), 240598. https://doi.org/10.1098/rsos.240598 https://doi.org/10.1098/rsos.240598 Self-archived version Yu, Y., Perumal, P., Sithole, T., & Luukkonen, T. (2025). Recovery of ammonium and nitrate from wastewater using adsorption-based techniques: A review. Journal of Cleaner Production, 519, 145976. https://doi.org/10.1016/j.jclepro.2025.145976 https://doi.org/10.1016/j.jclepro.2025.145976 Self-archived version Yu, Y., Bhuyan, M., Perumal, P., Luukkonen, T. (2025). Ammonium removal and recovery from municipal wastewater by ion exchange using porous metakaolin geopolymer granules. Manuscript submitted for publication. Tiivistelmä
Huokoiset geopolymeerirakeet ovat nousemassa lupaavaksi materiaaliksi korkean lisäarvon sovelluksiin, kuten adsorptioon ja ammoniumin (NH₄⁺) talteenottoon jätevedestä. Tämä väitöskirja esittelee kattavan tutkimuksen metakaoliinipohjaisten huokoisten geopolymeerirakeiden valmistuksesta, karakterisoinnista ja käytöstä hyödyntäen vaahdotusta, alkaliaktivointia sekä granulointia. Huokoisuutta lisättiin käyttämällä vaahdotusaineina joko vetyperoksidia (H₂O₂) tai yhdyskuntajätteenpolton lentotuhkaa, joka sisälsi metallista alumiinia (Al0). Huokoisuuden lisääntyminen, erityisesti mikro- ja nanokokoluokissa, paransi merkittävästi rakeiden ominaispinta-alaa ja NH₄⁺-adsorptiokapasiteettia – jopa 126 % verrattuna ei-huokoisiin rakeisiin. Paras suorituskyky saavutettiin 10 % H₂O₂-liuoksella. Rakeet osoittivat riittävää mekaanista lujuutta (≥2 MPa), ja niitä arvioitiin myös ioninvaihtokyvyn osalta. Vaikka lentotuhka lisäsi huokoisuutta, se aiheutti haitallisten aineiden, kuten antimonin ja vanadiinin, liukenemista, minkä vuoksi optimaalinen tuhkapitoisuus rajoitettiin 0.3 paino-% Al0:aan. Adsorptio-desorptiotutkimukset osoittivat, että huokoiset geopolymeerirakeet saavuttivat keskimääräisen NH₄⁺-ottokapasiteetin jopa 9.0 mg/g ja NH₄⁺-saannon 51–98 % 30 adsorptio- ja desorptiosyklin aikana, kun KNO3 20:a regeneroivana aineena käytettiin, vaikka suorituskyky heikkeni syklin jälkeen. Pitkän aikavälin käytössä suorituskyky kuitenkin heikkeni. Kunnallisen jäteveden käsittelyssä havaittiin huokosten tukkeutumista ja pintaan kertyvää kiintoainesta, mikä korostaa esikäsittelyn merkitystä. Yhteenvetona voidaan todeta, että huokoiset geopolymeerirakeet ovat käyttökelpoinen, uudelleenkäytettävä ja tehokas materiaali NH₄⁺:n talteenottoon, edistäen typen kiertotaloutta ja kestävää jäteveden käsittelyä. Osajulkaisut Yu, Y., Perumal, P., Corfe, I. J., Paul, T., Illikainen, M., & Luukkonen, T. (2023). Combined granulation–alkali activation–direct foaming process: A novel route to porous geopolymer granules with enhanced adsorption properties. Materials & Design, 227, 111781. https://doi.org/10.1016/j.matdes.2023.111781 https://doi.org/10.1016/j.matdes.2023.111781 Rinnakkaistallennettu versio Luukkonen, T., Yu, Y., Adhikary, S. K., Kauppinen, S., Finnilä, M., & Perumal, P. (2024). Metallic aluminium in municipal solid waste incineration fly ash as a blowing agent for porous alkali-activated granules. Royal Society Open Science, 11(8), 240598. https://doi.org/10.1098/rsos.240598 https://doi.org/10.1098/rsos.240598 Rinnakkaistallennettu versio Yu, Y., Perumal, P., Sithole, T., & Luukkonen, T. (2025). Recovery of ammonium and nitrate from wastewater using adsorption-based techniques: A review. Journal of Cleaner Production, 519, 145976. https://doi.org/10.1016/j.jclepro.2025.145976 https://doi.org/10.1016/j.jclepro.2025.145976 Rinnakkaistallennettu versio Yu, Y., Bhuyan, M., Perumal, P., Luukkonen, T. (2025). Ammonium removal and recovery from municipal wastewater by ion exchange using porous metakaolin geopolymer granules. Manuscript submitted for publication. Academic dissertation to be presented with the assent of the Doctoral Programme Committee of Technology and Natural Sciences of the University of Oulu for public defence in the Oulun Puhelin auditorium (L5), Linnanmaa, on 10 October 2025, at 12 noonAbstract
Porous geopolymer granules are emerging as a promising material for high-value applications such as adsorption and ammonium (NH₄⁺) recovery from wastewater. This thesis presents a comprehensive investigation into the fabrication, characterization, and application of porous metakaolin-based geopolymer granules produced via direct foaming, one-part alkali activation, and high-shear granulation. Porosity was introduced using either hydrogen peroxide (H₂O₂) or municipal solid waste incineration fly ash containing metallic aluminum (Al0) as blowing agents. Increased porosity, particularly in the micro- and nanoscale range, significantly enhanced the specific surface area and NH₄⁺ adsorption capacity—up to 126% higher compared to nonporous granules, with optimal performance observed using 10% H₂O₂ solution. The granules demonstrated sufficient mechanical strength (≥2 MPa) and were evaluated for environmental safety and ion-exchange behavior. While fly ash improved porosity, it introduced leaching concerns for elements like antimony and vanadium, limiting its optimal content to 0.3 wt.% Al0. Adsorption-desorption studies showed that porous geopolymer granules achieved an average NH₄⁺ uptake capacity of up to 9.0 mg/g, and NH₄⁺ recovery of 51–98% over the 30 adsorption and desorption cycles using KNO₃ as a regenerant, though performance declined after 20 cycles. Application in municipal wastewater highlighted the need for pretreatment to mitigate pore blocking and surface fouling. Overall, these findings establish porous geopolymer granules as a feasible, regenerable, and effective material for NH₄⁺ recovery, contributing to circular nitrogen economy and sustainable wastewater treatment strategies.Tiivistelmä
Huokoiset geopolymeerirakeet ovat nousemassa lupaavaksi materiaaliksi korkean lisäarvon sovelluksiin, kuten adsorptioon ja ammoniumin (NH₄⁺) talteenottoon jätevedestä. Tämä väitöskirja esittelee kattavan tutkimuksen metakaoliinipohjaisten huokoisten geopolymeerirakeiden valmistuksesta, karakterisoinnista ja käytöstä hyödyntäen vaahdotusta, alkaliaktivointia sekä granulointia. Huokoisuutta lisättiin käyttämällä vaahdotusaineina joko vetyperoksidia (H₂O₂) tai yhdyskuntajätteenpolton lentotuhkaa, joka sisälsi metallista alumiinia (Al0). Huokoisuuden lisääntyminen, erityisesti mikro- ja nanokokoluokissa, paransi merkittävästi rakeiden ominaispinta-alaa ja NH₄⁺-adsorptiokapasiteettia – jopa 126 % verrattuna ei-huokoisiin rakeisiin. Paras suorituskyky saavutettiin 10 % H₂O₂-liuoksella. Rakeet osoittivat riittävää mekaanista lujuutta (≥2 MPa), ja niitä arvioitiin myös ioninvaihtokyvyn osalta. Vaikka lentotuhka lisäsi huokoisuutta, se aiheutti haitallisten aineiden, kuten antimonin ja vanadiinin, liukenemista, minkä vuoksi optimaalinen tuhkapitoisuus rajoitettiin 0.3 paino-% Al0:aan. Adsorptio-desorptiotutkimukset osoittivat, että huokoiset geopolymeerirakeet saavuttivat keskimääräisen NH₄⁺-ottokapasiteetin jopa 9.0 mg/g ja NH₄⁺-saannon 51–98 % 30 adsorptio- ja desorptiosyklin aikana, kun KNO3 20:a regeneroivana aineena käytettiin, vaikka suorituskyky heikkeni syklin jälkeen. Pitkän aikavälin käytössä suorituskyky kuitenkin heikkeni. Kunnallisen jäteveden käsittelyssä havaittiin huokosten tukkeutumista ja pintaan kertyvää kiintoainesta, mikä korostaa esikäsittelyn merkitystä. Yhteenvetona voidaan todeta, että huokoiset geopolymeerirakeet ovat käyttökelpoinen, uudelleenkäytettävä ja tehokas materiaali NH₄⁺:n talteenottoon, edistäen typen kiertotaloutta ja kestävää jäteveden käsittelyä
Nanostructured, functional, and flexible materials for energy conversion and storage systems
No full text
Assessing the carbonation potential of wood ash for CO2 sequestration
Full text linkAbstract
Wood ash, a byproduct of wood combustion, poses environmental challenges when disposed of in landfills. This study explores a sustainable alternative by investigating the carbonation of wood ash, a process converting CO2 into stable carbonate minerals. With increasing concerns about waste management, this research aims to identify optimal carbonation conditions by varying relative humidity, liquid-to-solid ratio (L/S), and temperature. Results demonstrate that the ideal conditions for wood ash carbonation involve a moderate relative humidity of 55%, room temperature at 25 °C, and a lower L/S ratio. Thermogravimetric analysis (TGA) indicates that extended curing times increase CaCO3 formation. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) confirm the presence of carbonate phases. Mechanical strength tests reveal that samples with lower porosity and higher carbonation products exhibit superior strength. This study contributes to the understanding of wood ash carbonation but also emphasizes its potential practical applications in construction materials as light aggregates in cement concrete. The research explores the implications for sustainable waste management, offering insights into environmentally and economically viable solutions for wood ash recycling.摘要
草木灰是木材燃烧的副产品，直接填埋会导致环境问题。本文提出了一种可持续的替代方案，通过调控草木灰的碳化过程，将CO 转化为稳定的碳酸盐。在废弃物处理日益受到关注的背景下，本文通过调节相对湿度、液固比(L/S)和温度，确定了最佳碳化条件。研究结果显示，草木灰碳化的理想条件是相对湿度55%、室温25℃以及较低的液固比。热重分析(TGA)表明，延长养护时间可以促进CaCO 的生成；扫描电镜(SEM)和X射线衍射(XRD)证实了碳酸盐相的存在。力学性能试验表明，孔隙率低且碳化程度高的试件具有更高的强度。本研究不仅有助于理解草木灰的碳化过程，还强调了其在制备轻质骨料等建筑材料中的应用价值，提供了一种可行的、环保且经济的草木灰回收解决方案。Abstract
Wood ash, a byproduct of wood combustion, poses environmental challenges when disposed of in landfills. This study explores a sustainable alternative by investigating the carbonation of wood ash, a process converting CO2 into stable carbonate minerals. With increasing concerns about waste management, this research aims to identify optimal carbonation conditions by varying relative humidity, liquid-to-solid ratio (L/S), and temperature. Results demonstrate that the ideal conditions for wood ash carbonation involve a moderate relative humidity of 55%, room temperature at 25 °C, and a lower L/S ratio. Thermogravimetric analysis (TGA) indicates that extended curing times increase CaCO3 formation. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) confirm the presence of carbonate phases. Mechanical strength tests reveal that samples with lower porosity and higher carbonation products exhibit superior strength. This study contributes to the understanding of wood ash carbonation but also emphasizes its potential practical applications in construction materials as light aggregates in cement concrete. The research explores the implications for sustainable waste management, offering insights into environmentally and economically viable solutions for wood ash recycling.摘要
草木灰是木材燃烧的副产品，直接填埋会导致环境问题。本文提出了一种可持续的替代方案，通过调控草木灰的碳化过程，将CO 转化为稳定的碳酸盐。在废弃物处理日益受到关注的背景下，本文通过调节相对湿度、液固比(L/S)和温度，确定了最佳碳化条件。研究结果显示，草木灰碳化的理想条件是相对湿度55%、室温25℃以及较低的液固比。热重分析(TGA)表明，延长养护时间可以促进CaCO 的生成；扫描电镜(SEM)和X射线衍射(XRD)证实了碳酸盐相的存在。力学性能试验表明，孔隙率低且碳化程度高的试件具有更高的强度。本研究不仅有助于理解草木灰的碳化过程，还强调了其在制备轻质骨料等建筑材料中的应用价值，提供了一种可行的、环保且经济的草木灰回收解决方案
Tailoring the shell structures in core-shell metal nanostructures for improved catalytic reduction of nitroaromatics
No full textCore-shell metal nanostructures have garnered significant attention from researchers worldwide in recent years due to their size- and shape-dependent properties, which arise from the synergistic effects between the core and shell. These properties are particularly valuable for applications in catalysis. This review focuses on recent advancements in the synthesis of various metal shell layers on cores of different sizes and shapes for the catalytic reduction of nitroaromatics. Initially, recent contributions to the synthesis of diverse bimetallic nanostructures, including hollow, crown-jewel, alloy, and core-shell architectures are summarized. Subsequently, the influence of tailoring metal shells, including monolayer, bilayer, and alloy layer metal shells on core metals, on the catalytic activity of nitroaromatics is discussed. This review highlights significant progress in the design and synthesis of various nanostructures and compositions through precise control of nucleation and growth processes using specific synthetic methods. Moreover, the discussion focused on how the catalytic reduction of nitroaromatics is influenced by the synergistic effect when different layers of metal shells are applied to the core. Furthermore, the advantages and limitations associated with the synthesis of core-shell nanostructures are highlighted in each section. Finally, perspectives on future research directions for core-shell metal nanostructures are provided
Therapeutic effect of Saraca asoca (Roxb.) Wilde on lysosomal enzymes and collagen metabolism in adjuvant induced arthritis
No full text- …
