1,720,983 research outputs found
Filling Fresh Metakaolin‐Based Geopolymer Paste with Wood Ash: Chemical and Mechanical Characterization
No full textAssessing the carbonation potential of wood ash for CO2 sequestration
Get PDFAbstract
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
Si/Polymer/Natural Drug Materials Prepared by Sol–Gel Route: Study of Release and Antibacterial Activity
No full textMosses on Geopolymers: Preliminary Durability Study and Chemical Characterization of Metakaolin-Based Geopolymers Filled with Wood Ash
No full textBurning wood is estimated to produce about 6–10% of ash. Despite the possibility of recycling wood ash (WA), approximately 70% of the wood ash generated is landfilled, causing costs as well as environmental pollution. This study aims to recycle WA in an alternative way by inserting it as filler in geopolymeric materials. Here, metakaolin, NaOH, sodium silicate, and WA are used to realize geopolymers. Geopolymers without and with 10, 20 and 30% of WA are synthesized and characterized after 7, 14, 28 and 56 days. The article’s study methods are related to geopolymers’ chemical, biological and mechanical properties. The geopolymers synthesized are compact and solid. The pH and conductivity tests and the integrity and weight loss tests have demonstrated the stability of materials. The FT-IR study and boiling water test have confirmed the successful geopolymerization in all samples. The antibacterial analysis, the moss growing test and the compressive strength test have given a first idea about the durability of the materials synthesized. Furthermore, the compressive strength test result has allowed the comparison from the literature of the specimens obtained with the Portland cement (PC). The results obtained bode well for the future of this material
Metakaolin-Based Geopolymers Filled with Industrial Wastes: Improvement of Physicochemical Properties through Sustainable Waste Recycling
No full textThe increasing global demand for cement significantly impacts greenhouse gas emissions and resource consumption, necessitating sustainable alternatives. This study investigates fresh geopolymer (GP) pastes incorporating 20 wt.% of five industrial wastes—suction dust, red mud from alumina production, electro-filter dust, and extraction sludges from food supplement production and from partially stabilized industrial waste—as potential replacements for traditional cement. Consistent synthesis methods are used to prepare the geopolymers, which are characterized for their physicochemical, mechanical, and biological properties. Ionic conductivity and pH measurements together with integrity tests, thermogravimetry analysis (TGA), and leaching analysis are used to confirm the stability of the synthesized geopolymers. Fourier-transform Infrared (FT-IR) spectroscopy is used to follow geopolymerization occurrences. Results for ionic conductivity, pH, and integrity revealed that the synthesized GPs were macroscopically stable. TGA revealed that the main mass losses were ascribable to water dehydration and to water entrapped in the geopolymer networks. Only the GP filled with the powder of the red mud coming from alumina production experienced a mass loss of 23% due to a partial waste degradation. FT-IR showed a red shift in the main Si-O-(Si or Al) absorption band, indicating successful geopolymer network formations. Additionally, most of the GPs filled with the wastes exhibited higher compressive strength (37.8–58.5 MPa) compared to the control (22 MPa). Only the GP filled with the partially stabilized industrial waste had a lower mechanical strength as its structure was highly porous because of gas formation during geopolymerization reactions. Despite the high compressive strength (58.5 MPa) of the GP filled with suction dust waste, the concentration of Sb leached was 25 ppm, which limits its use. Eventually, all samples also demonstrated effective antimicrobial activity against Escherichia coli and Staphylococcus aureus due to the alkaline environment and the presence of metal cations able to react with the bacterial membranes. The findings revealed the possibility of recycling these wastes within several application fields
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Bootstrapping an Italian VerbNet: data-driven analysis of verb alternations
Get PDFThe goal of this paper is to propose a classification of the syntactic alternations admitted by the most frequent Italian verbs. The data-driven two-steps procedure exploited and the structure of the identified classes of alternations are presented in depth and discussed. Even if this classification has been developed with a practical application in mind, namely the semi-automatic building of a VerbNet-like lexicon for Italian verbs, partly following the methodology proposed in the context of the VerbNet project, its availability may have a positive impact on several related research topics and Natural Language Processing tasks
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
- …
