Recent progress in environmentally friendly geopolymers: A review.

New food packaging materials provide an attractive option for the advancement of nanomaterials. The poor thermal, mechanical, chemical, and physical properties of biopolymers and their inherent per...

Impact of metal nanoparticles on the mechanical, barrier, optical and thermal properties of biodegradable food packaging materials.

This study synthesized and characterized composites of graphene oxide and TiO2 (GO-TiO2). GO-TiO2 thin films were deposited using the doctor blade technique. Subsequently, the thin films were sensitized with a natural dye extracted from a Colombian source (Bactris guineensis). Thermogravimetric analysis, X-ray diffraction, Raman spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance measurements were used for physico-chemical characterization. All the samples were polycrystalline in nature, and the diffraction signals corresponded to the TiO2 anatase crystalline phase. Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR) verified the synthesis of composite thin films, and the SEM analysis confirmed the TiO2 films morphological modification after the process of GO incorporation and sensitization. XPS results suggested a possibility of appearance of titanium (III) through the formation of oxygen vacancies (Ov). Furthermore, the optical results indicated that the presence of the natural sensitizer and GO improved the optical properties of TiO2 in the visible range. Finally, the photocatalytic degradation of methylene blue was studied under visible irradiation in aqueous solution, and pseudo-first-order model was used to obtain kinetic information about photocatalytic degradation. These results indicated that the presence of GO has an important synergistic effect in conjunction with the natural sensitizer, reaching a photocatalytic yield of 33%.

https://royalsocietypublishing.org/doi/pdf/10.1098/rsos.181824

Photocatalytic activity of graphene oxide-TiO 2 thin films sensitized by natural dyes extracted from Bactris guineensis

The effect of nanomaterials on properties of geopolymers derived from industrial by-products: A state-of-the-art review

Au-TiO2/SiO2 photocatalysts with NOx depolluting activity: Influence of gold particle size and loading

Use of silicon dioxide (SiO2) and titanium dioxide (TiO2) have been widely investigated individually in coatings technology, but their combined properties promote compatibility for different innovative applications. For example, the photocatalytic properties of TiO2 coatings, when exposed to UV light, have interesting environmental applications, such as air purification, self-cleaning and antibacterial properties. However, as reported in different pilot projects, serious durability problems, associated with the adhesion between the substrate and TiO2, have been evidenced. Thus, the aim of this work is to synthesize SiO2 together with TiO2 to increase the durability of the photocatalytic coating without affecting its photocatalytic potential. Therefore, synthesis using sonochemistry, synthesis without sonochemistry, physical characterization, photocatalytic evaluation, and durability of the SiO2, SiO2@TiO2 and TiO2 coatings are presented. Results indicate that using SiO2 improved the durability of the TiO2 coating without affecting its photocatalytic properties. Thus, this novel SiO2@TiO2 coating shows potential for developing long-lasting, self-cleaning and air-purifying construction materials.

SiO2@TiO2 Coating: Synthesis, Physical Characterization and Photocatalytic Evaluation

Life Cycle Assessment (LCA) is considered an innovative tool to analyze environmental impacts to make decisions aimed at improving the environmental performance of building materials and construction processes throughout different life cycle stages, including design, construction, use, operation, and end-of-life (EOL). Therefore, during the last two decades, interest in applying this tool in the construction field has increased, and the number of articles and studies has risen exponentially. However, there is a lack of consolidated studies that provide insights into the implementation of LCA on construction and demolition waste (C&DW). To fill this research gap, this study presents a literature review analysis to consolidate the most relevant topics and issues in the research field of C&DW materials and how LCA has been implemented during the last two decades. A systematic literature search was performed following the PRISMA method: analysis of selected works is based on bibliometric and content-based approaches. As a result, the study characterized 150 selected works in terms of the evolution of articles per year, geographical distribution, most relevant research centers, and featured sources. In addition, this study highlights research gaps in terms of methodological and design tools to improve LCA analysis, indicators, and connection to new trending concepts, such as circular economy and industry 4.0.

Life Cycle Assessment on Construction and Demolition Waste: A Systematic Literature Review

The effect of the TiO2 addition on the physicomechanical properties of a geopolymer system based on metakaolin (MK) and hydroxide and potassium silicate as activators is presented in this article. Three different liquid-solid systems (0.35, 0.40, and 0.45) and two titanium additions were investigated (5% and 10% of the cement content). The flowability, setting time, and mechanical strength of the geopolymer mixtures and their microstructural characteristics were evaluated using techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). It was concluded that a percentage of up to 10% TiO2 does not affect the mechanical properties of the geopolymer, although it does reduce the fluidity and setting times of the mixture.

https://www.mdpi.com/2079-6412/7/12/233/pdf

Metakaolin-Based Geopolymer with Added TiO2 Particles: Physicomechanical Characteristics

Green roof systems, a technology which was used in major ancient buildings, are currently becoming an interesting strategy to reduce the negative impact of traditional urban development caused by ground impermeabilization. Only regarding the environmental impact, the application of these biological coatings on buildings has the potential of acting as a thermal, moisture, noise, and electromagnetic barrier. At the urban scale, they might reduce the heat island effect and sewage system load, improve runoff water and air quality, and reconstruct natural landscapes including wildlife. In spite of these significant benefits, the current design and construction methods are not completely regulated by law because there is a lack of knowledge of their technical performance. Hence, this review of the current state of the art presents a proper green roof classification based on their components and vegetation layer. Similarly, a detailed description from the key factors that control the hydraulic and thermal performance of green roofs is given. Based on these factors, an estimation of the impact of green roof systems on sustainable construction certifications is included (i.e., LEED—Leadership in Energy and Environment Design, BREEAM—Building Research Establishment Environmental Assessment Method, CASBEE—Comprehensive Assessment System for Built Environment Efficiency, BEAM—Building Environmental Assessment Method, ESGB—Evaluation Standard for Green Building). Finally, conclusions and future research challenges for the correct implementation of green roofs are addressed.

State-of-the-Art Green Roofs: Technical Performance and Certifications for Sustainable Construction

Green roof systems represent an opportunity to mitigate the effect of natural soil loss due to the development of urban infrastructure, which significantly affects natural processes such as the hydrological water cycle. This technology also has the potential to reduce the indoor building temperature and increase the durability of waterproof membranes, reduce run-off water and heat island effects, create meeting places, and allow the development of biological species. However, despite the described benefits, the use of this technology is still limited due to the costs and the environmental impact from using non-renewable building materials. Therefore, this article presents the hydraulic and thermal analysis of different semi-intensive green roofs using recycled (rubber and high density polyethylene (HDPE) trays) and reused materials (polyethylene (PET) bottles) in their drainage layers. Then, three roof systems were evaluated and compared to traditional drainage systems made with natural stone aggregates. Results showed that some systems are more useful when the goal is to reduce temperature, while others are more effective for water retention. Additionally, this study presents evidence of the potential of reducing the dead loads and costs of green roofs by using recycled and reused materials in drainage systems.

Aníbal Maury-Ramírez

Papers

SiO2@TiO2 Coating: Synthesis, Physical Characterization and Photocatalytic Evaluation

Life Cycle Assessment on Construction and Demolition Waste: A Systematic Literature Review

Metakaolin-Based Geopolymer with Added TiO2 Particles: Physicomechanical Characteristics

State-of-the-Art Green Roofs: Technical Performance and Certifications for Sustainable Construction

Evaluation of Semi-Intensive Green Roofs with Drainage Layers Made Out of Recycled and Reused Materials