Evaluation of band gap energy of TiO2 precipitated from titanium sulphate

The determination of the band gap energy () of semiconductors powder materials can be performed from diffuse reflectance spectroscopy (DRS) measurements. For this purpose, the classical theory proposed by Kubelka and Munk (K-M) and the so-called plot Tauc, both discussed here, have been largely employed. We investigate the values of anatase TiO2 particles synthesized by precipitation of titanyl sulphate in the presence of 5% ammonia solution and titanium and iron salts. Based on K-M function and Tauc plot and considering that the TiO2 anatase phase is an indirect band gap semiconductor, our results indicate that the samples subjected to a mechanochemical treatment (mill rotation speed equal to 300 rpm) present substantially lower values compared to those reported by other authors in a recent work(undefined

Applied optics in the development of smart asphalt mixtures

The functionalization of asphalt mixtures is carried out in order to provide new capabilities to the road pavements, with major social, environmental and financial benefits. Optical characterization techniques as well as optical processes like photocatalysis play a major role in the development of new asphalt mixtures with smart functions. These advanced capabilities which are being developed in asphalt mixtures are: photocatalytic, superhydrophobic, self-cleaning, de-icing/anti-ice, self-healing, thermochromic, and latent heat thermal energy storage. The main objective of this research work is to stress the importance of optics and photonics technologies giving an overview of advanced functionalized smart asphalt mixtures.This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UIDB/04650/2020. This work was partially financed by FCT - Fundação para a Ciência e a Tecnologia - under the projects of the Strategic Funding UIDB/04650/2020, MicroCoolPav project EXPL/EQU-EQU/1110/2021, and NanoAir project PTDC/FISMAC/6606/2020

Photocatalytic performance of textiles coated with titanium dioxide-reduced graphene oxide system for degradation of crude petroleum under similar solar irradiation

The pollution caused by oil and its toxic derivatives presents a considerable risk to the public health and the environment. This work is devoted to the study of the influence of TiO2 nanoparticles immobilized on three types of textiles materials (Cotton, Entretela, and Polylactic Acid-PLA) coated with reduced graphene oxide (RGO) to be used for degradation of crude petroleum under simulated solar irradiation. The morphological studies of the functionalized textiles substrates were performed by using Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy, which indicated an excellent dispersion and adhesion of nanoparticles of about 60% (atomic %Ti) on the textile fibers covered with RGO after washing. Ultraviolet-visible Diffuse Reflectance spectra suggest a reduction in the band gap energy of TiO2 up to 2.86 eV due to the presence of RGO. The functionalized textiles presented at least 60% of photocatalytic efficiency measured by Rhodamine B degradation, decreasing less than 12% after the rigorous washing. The excitation/emission Synchronous Fluorescence Spectroscopy and Fourier-transform Infrared spectroscopies demonstrated a great potential for photocatalytic degradation of the functionalized textiles substrates as the appearance of the hydroxyl, carboxyl, and the C-O bands confirm the photoinduced oxidation of the organic compounds implying with high prospects in petroleum and wastewater treatment areas. Moreover, this environmentally friendly, sustainable, and inclusive research work can be included in clean technologies, contributing to the novel socio-economic model recognized as "Green Recovery".[GRAPHICS].This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2019 and the project PTDC/FIS-MAC/6606/2020. Also, the third author would like to acknowledge the FCT for the Ph.D. scholarship (SFRH/BD/137421/2018). Moreover, the authors would like to acknowledge Sociedade Nacional de Combusti ' veis de Angola (Sonangol), which partially provided the crude oil samples

Use and misuse of the Kubelka-Munk function to obtain the band gap energy from diffuse reflectance measurements

The determination of the optical band gap energy (Eg ) is important for optimization of the generation of electron/hole pairs in semiconductor materials under illumination. For this purpose, the classical theory proposed by Kubelka and Munk (K-M) has been largely employed for the study of amorphous and polycrystalline materials. In this paper, the authors demonstrate, step by step, how to use the K-M function and apply it thoroughly to the determination of the Eg of TiO2 semiconductor powder (pressed at different thicknesses) from diffuse reflectance spectroscopy (DRS) measurements. For the sample thicknesses 1–4 mm, Eg values of 3.12–3.14 eV were obtained. With this work it is envisaged a clarification to the procedure of determination of the Eg from the K-M theory and DRS data, since some drawbacks, and misconceptions have been identified in the recent literature. In particular, the widely used practice of determining the Eg of a material directly from the K-M function is found to be inadequate

Mitigation of urban heat island effects by thermochromic asphalt pavement

Asphalt road pavements are usually dark and, consequently, have a low albedo. Therefore, they absorb energy as heat, increasing the Urban Heat Island (UHI) effect, which impacts the environment, energy consumption, and human health. Through the functionalization with thermochromic materials (TM), this work aims to develop a smart asphalt pavement able to change its surface color, increasing the reflectance, and thus mitigate this phenomenon. To achieve this goal, asphalt substrates were functionalized by a surface spray coating of a thermochromic solution (TS) containing aqueous solution of thermochromic microcapsules (thermocapsules), dye, and epoxy resin. To evaluate the functionalization features, Fourier Transform Infrared Spectroscopy (FTIR), and Thermal Differential test (TDT) with cyclic temperature variation were performed in the functionalized asphalt binder. Moreover, Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectrometry (EDS), a Quick Ultraviolet Accelerated Weathering Test (QUV) with Colorimetry test, and an adaptation of the Accelerated Polishing Test (APT) were performed on the functionalized asphalt mixture. The results indicate that the functionalization of asphalt substrates with TS exhibits a reversible color-change ability, higher luminosity values when subjected to temperatures above 30 C, and wear resistance

Advancements in phase change materials in asphalt pavements for mitigation of urban heat island effect: bibliometric analysis and systematic review

This research presents a dual-pronged bibliometric and systematic review of the integration of phase change materials (PCMs) in asphalt pavements to counteract the urban heat island (UHI) effect. The bibliometric approach discerns the evolution of PCM-inclusion asphalt research, highlighting a marked rise in the number of publications between 2019 and 2022. Notably, Chang’an University in China has emerged as a leading contributor. The systematic review addresses key questions like optimal PCM types for UHI effect mitigation, strategies for PCM leakage prevention in asphalt, and effects on mechanical properties. The findings identify polyethylene glycols (PEGs), especially PEG2000 and PEG4000, as prevailing PCMs due to their wide phase-change temperature range and significant enthalpy during phase transitions. While including PCMs can modify asphalt’s mechanical attributes, such mixtures typically stay within performance norms. This review emphasises the potential of PCMs in urban heat management and the need for further research to achieve optimal thermal and mechanical balanceThis research was partially funded by the Portuguese Foundation for Science and Technology (FCT) under the framework of the projects MicroCoolPav EXPL/EQU-EQU/1110/2021, NanoAir PTDC/FIS-MAC/6606/2020, UIDB/04650/2020, and UIDB/04029/2020. This research was also supported by the doctoral Grant PRT/BD/154269/2022 financed by the FCT, and with funds from POR Norte-Portugal 2020 and State Budget, under MIT Portugal Program. I.R.S. would like to acknowledge the FCT for funding (2022.00763.CEECIND). V.C.B. acknowledges the Fundação Cearense de Apoio ao Desenvolvimento Científico e Tecnológico (Funcap), MLC-0191- 00144.01.00/22 (Edital Mulheres na Ciência), and the National Council for Scientific and Technological Development (CNPq), Process 404978/2021-5—Call CNPq/MCTI/FNDCT N° 18/2021—Faixa B—Consolidated Groups

Asphalt binder "Skincare"? aging evaluation of an asphalt binder modified by Nano-TiO2

Aging by oxidation of asphalt roadway material promotes changes in its physical, chemical, and rheological properties, affecting its hardening and accelerating the degradation of its corresponding asphalt mixture. Titanium dioxide (TiO2) has been applied in engineering investigations to promote anti-aging and photocatalytic properties. In this study, a commercial binder was modified with nano-TiO2 (using contents of 0.1, 0.25, 0.5, 1, 2, 3, and 6%). It was evaluated by physicochemical and rheological tests (penetration, softening point, mass loss, dynamic viscosity, rheology, and Fourier transform infrared spectroscopy-FTIR) before and after aging by rolling thin-film oven test (RTFOT) and pressure aging vessel (PAV). The results indicated that incorporating nano-TiO2 mitigates binder aging, pointing out 0.25% as an optimum modification content for the investigated asphalt binder.This research was partially funded by the Portuguese Foundation for Science and Technology (FCT), PhD scholarship SFRH/BD/137421/2018, NanoAir PTDC/FISMAC/6606/2020, UIDB/04650/2020, and UIDB/04029/2020. V.C.B. would like to acknowledge National Council for Scientific and Technological Development (CNPq) for the funding on behalf of the scholarship 308360/2017-6. Furthermore, we would like to thank the Industrial Research Fund (IOF) for funding the PAPPoA project (IOF/SBO/41859/2020)

Pavimentos rodoviários termosensitivos: funcionalização com termocápsulas para mitigação dos efeitos de ilha de calor

A coloração preta dos pavimentos rodoviários acentua a absorção de energia em forma de calor e contribui para o fenómeno de ilha de calor, que possui impactos relacionados com o ambiente, o consumo de energia e a saúde. Através da concessão de novas habilidades (funcionalização) por aspersão superficial de um revestimento contendo uma solução com corante e partículas termocromáticas (termocápsulas), cuja mudança de cor é sensível a variações de temperatura, foi possível alterar reversivelmente a cor da superfície do pavimento a partir de 30 °C e apresentar uma solução capaz de ajudar a reduzir a temperatura em meio urbano.Os autores agradecem o apoio da Fundação para a Ciência e Tecnologia (FCT), NanoAir PTDC/FISMAC/6606/2020, UIDB/04650/2020 e UIDB/04029/2020

Evaluation of the best solution for the functionalization of photocatalytic, superhydrophobic, and self-cleaning properties on asphalt mixtures

This research aims to develop asphalt mixtures with new capabilities with photocatalytic, superhydrophobic, and self-cleaning capabilities. Different solutions were prepared combining nano-TiO2 and micro-PTFE on water, and ethyl alcohol and dimethyl ketone with different concentrations. The solutions were sprayed over the asphalt mixtures and the new capabilities were evaluated via decolourization of Rhodamine B dye aqueous solution under simulated solar irradiation and Water Contact Angle measurements. Among the combinations analysed, the best solution was TiO2 PTFE with ethyl alcohol (8 g/L)

Photocatalytic performance of textiles coated with TiO2-RGO system for degradation of crude petroleum under similar solar irradiation

The pollution caused by oil and its toxic derivatives presents a considerable risk to the public health and the environment. Here, we studied the influence of TiO2 nanoparticles immobilized on three types of textiles materials (Cotton, Entretela and PLA) coated with reduced graphene oxide (RGO) to be used for degradation of crude petroleum under simulated solar irradiation. The morphological studies of the functionalized textiles substrates were performed by using Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy, which indicated an excellent dispersion and adhesion of nanoparticles on the textile fibres covered with RGO. Ultraviolet–visible Diffuse Reflectance spectra suggests a reduction in the band gap energy of TiO2 due to the presence of RGO. The excitation/emission Synchronized Fluorescence and Fourier transform Infrared spectroscopies demonstrated that the functionalized textiles substrates exhibit a great potential for photocatalytic degradation of organic compounds with high prospects in petroleum and wastewater treatment areas