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10 results on '"Francisco X. Nobre"'

1. Effect of thermal annealing on kaolin from the Amazon region, aiming at the production of geopolymer

Author

Luz M.A. Maruoka, Isnailson F. Pinheiro, Hilderson S. Freitas, Francisco X. Nobre, and Luis V.A. Scalvi

Subjects
Geopolymer, Kaolin, Amazon, Thermal annealing, Mining engineering. Metallurgy, TN1-997
Abstract

In the focus of environmental problems and climate change, research for alternative materials becomes essential. In this sense, research on geopolymers is very relevant, due to its sustainability characteristics linked to mechanical and physical properties. Metakaolin is a geopolymer precursor and obtained from kaolin, whose characteristics, which are specific to each region, impact on the characteristics of metakaolinite, which in turn influences the production of geopolymer. Characteristics of metakaolin from the Amazon region are not well known, with few publications, despite the importance of the region in the international context in terms of natural resources and environmental. In order to contribute to this research, the present investigation analyses the effect of thermal annealing temperature on kaolin and verifies the suitability of metakaolin as a precursor of geopolymer products. The kaolin in natura was benefited by wet sieving and thermally treated in the range 600 °C to 800 °C. Samples were characterized by XRD, with phases quantification and amorphous fraction obtained by Rietveld method, XRF, TG/DTG, specific surface area, laser granulometry, FTIR, SEM and EDS. An average specific surface area of 1.32 m2/g was identified for kaolin treated at 700 °C, where the amorphous fraction is 91.6% which has almost reached saturation, varying slightly to 800 °C as thermal annealing temperature. Considering environmental aspects and the energy savings, one may state that samples treated at 700 °C may efficiently be used as geopolymer precursor material. The vibration of the O–H bond in kaolinite treated at temperatures greater than 650 °C was not identified. Results suggest that the metakaolinite obtained from Amazon kaolin is indicated for geopolymer production.

Published
2023
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2. Hydrogen production from aqueous glycerol using titanate nanotubes decorated with Au nanoparticles as photocatalysts

Author

THALLES M.F. MARQUES, REINALDO N. MORAIS, FRANCISCO X. NOBRE, JARDEL M. ROCHA, ANUPAMA GHOSH, THIAGO ANDRÉ S. SOARES, BARTOLOMEU C. VIANA, GIOVANNA MACHADO, JEAN CLAUDIO S. COSTA, and JOSÉ M.E. DE MATOS

Subjects
Titanate nanotubes, Au nanoparticles, catalytic hydrogen production, glycerol, Science
Abstract

Abstract: Protonated titanate nanotubes (HTiNts) were synthesized using the hydrothermal method, followed by proton exchange with acid. Gold nanoparticles decorated titanate nanotubes (AuHTiNts) were obtained by the reduction of AuCl4- under vigorous stirring with an aqueous solution of HTiNts containing 1 wt% of ascorbic acid. To investigate the surface structural chemistry of the titanate and AuHTiNts, the following characterization methods were used: scanning and transmission electron microscopy, X-ray diffraction, UV-Vis diffuse reflectance spectroscopy, Raman spectroscopy and X-ray photo-electron spectroscopy. The mean internal and external diameters for titanate nanotubes were found to be 5.46 ± 0.08 nm and 8.42 ± 0.03 nm, respectively, whereas the mean diameter of gold nanoparticles was measured to be 9.68 nm ± 0.03 nm. The as-synthesized AuHTiNts was used as photocatalyst in hydrogen production from glycerol as a sacrificial agent. The enhancement in the production of hydrogen, using the heterogeneous AuHTiNts catalysts, can be attributed to the intrinsic catalytic potential of gold as well as its interactions with titanate nanostructure.

Published
2019
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4. Study of Metakaolinite Geopolymeric Mortar with Plastic Waste Replacing the Sand: Effects on the Mechanical Properties, Microstructure, and Efflorescence

Author

Ivana Soares, Francisco X. Nobre, Raimundo Vasconcelos, and Miguel A. Ramírez

Subjects
General Materials Science, geopolymer, sustainability, plastic waste, metakaolinite, efflorescence
Abstract

In this study, the production of a mortar was proposed in which plastic waste replaced sand by 0%, 50%, and 100% in order to create a sustainable alternative for construction. The performance of the mortars was tested with two types of activators, one with NaOH, as a simple activator, and the other with NaOH and Na2SiO3, as a compound activator. The effects of the LDPE plastic bag waste and the activators on compressive strength, porosity, microstructure analysis, and efflorescence formation were correlated and discussed. The results showed that the replacement of sand with plastic waste at 50% and 100% proportionally reduced the compressive strength due to the increase in porosity caused by the waste, especially in the group of mortars with the simple activator, and included the formation of efflorescence. On the other hand, the compound activator increased the packing of the particles in the mortar, as observed in the images of the microstructure. This reduced porosity inhibited efflorescence and resulted in higher resistances that reached a maximum value of 22.68 MPa at 28 days in the group of 50% mortars with the compound activator. Therefore, the study showed that there is potential for the replacement of sand with plastic waste for the production of mortars, which can be considered a more sustainable building material.

Published
2022

9. Biodiesel Production from Tucumã ( Astrocaryum Aculeatum Meyer) Almond Oil Applying the Electrolytic Paste of Spent Batteries as a Catalyst

Author

Flávio Augusto De Freitas, Igor R. S. Mendonça, Silma de S. Barros, Wanison A. G. Pessoa Jr., Ingrity S. Costa Sá, Larissa M. Barroso, Edson P. da Silva, Marco A. S. Farias, Francisco X. Nobre, Paulo J. S. Maia, Stefan Iglauer, and Kaori K. Y. Isla

Subjects
History, Polymers and Plastics, Business and International Management, Industrial and Manufacturing Engineering
Published
2021
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10. List of contributors

Author

Buzuayehu Abebe, S.K. Ajithaa, N.S. Alfia, Abuzer Amir, Embalil Mathachan Aneesh, A. Archana, R. Arulvel, Sangeetha Arunachalam, null Ashish, Jose Gnanaleela Aswin Jeno, Sthita Pragnya Behera, B. Bharathiraja, Pooja Bhardwaj, Nilutpal Bhuyan, Parameswaran Binod, Neelam Bora, Arghya Chakravorty, Ramachandran Chelliah, Sivasankaran Chozhavendhan, Patitapaban Dash, Flávio A. de Freitas, Ponnuswamy Renuka Devi, Vivek Dhand, Balaji Dhandapani, Lakshman Kumar Dogiparthi, Anurag Dutta, Rajalakshmanan Eshwaramoorthy, T. Gajendran, Lekshmi Gangadhar, Sujay Ghosh, G. Gowshikaa, Neeraj Gupta, R.V. Hemavathy, J. Jayabharathi, Mani Jayakumar, R. Jayasree, S. Jeevanantham, Senthilkumar Kandasamy, A. Karthic, Guruviah Karthigadevi, S. Karthikadevi, M. Karthikeyan, Rupam Kataki, Imran Khan, V. Kirubakaran, Jayachandran Krishna, Suresh Kumar Krishnan, Kannaiyan Sathish Kumar, Madhava Anil Kumar, Naresh Kumar, P. Senthil Kumar, Pratyush Kumar Das, Manonmani Kumaraguruparaswami, S. Chaitanya Kumari, Dibyajit Lahiri, Jaya Lakkakula, Márcia S.F. Lira, G. Carlin Geor Malar, Anurag Malik, Prasad Mandade, Naveen Kumar Manickam, S. Manikandan, Bishwambhar Mishra, Rajkamal Mohan, Gokilam Mohankumar, H.C. Ananda Murthy, K. Muthukumar, Moupriya Nag, Senthil Nagappan, Ekambaram Nakkeeran, Abhishek Nalluri, M. Narmatha, Vinod Kumar Nathan, Francisco X. Nobre, Deog-Hwan Oh, P. Naga Padma, Ashok Pandey, Sherly A. Paul, Aditya Amrut Pawar, Ayyappasamy Sudalaiyadum Perumal, Wanison A.G. Pessoa, N. Prabhu, Venkatesa Prabhu S, Minakshi Prasad, K.M. Prasannakumaran, Bidyut Prava Das, N. Praveen, R. Praveen Kumar, D. Premkumar, Himani Punia, S. Rachel, Murgan Rajamehala, Selvarasu Ranganathan, Gulzar Ahmed Rather, Sathish Raam Ravichandran, Rina Rani Ray, Sharrel Rebello, C. Nagendranatha Reddy, R. Reshmy, Huria Rizvi, S. Samraj, Siva Sankar Sana, S. Sangeetha Gandhi, C. Sanjay Kumar, A. Saravanan, Muthulingam Seenuvasan, I. Aberna Ebenezer Selvakumari, G. Adaikala Selvan, Mothil Sengottian, Parvati Sharma, S. Sharvari, Raveendran Sindhu, Bharati Singh, M. Vijay Pradhap Singh, R. Subbaiya, Kavitha Subbiah, Rajaram Sundaramoorthy, Caroline Mercy Andrew Swamidoss, Mitsuo L. Takeno, Deepa Thomas, Anitha Thulasisingh, Belachew Zegale Tizazu, Jayanti Tokas, Rajamanickam Usha, V.L. Vasantha, Kamini Velhal, Chidambaram Kulandaisamy Venil, M. Venkata Ratnam, Chitra Devi Venkatachalam, Krishnan Vignesh, Y. Vineetha, Ravichandran Viveka, Shuai Wei, P.R. Yaashikaa, and Rajasri Yadavalli

Published
2021
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