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- 저자 : Nnabuk Okon Eddy (검색결과 2 건)
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Nnabuk Okon Eddy,Rajni Garg,Rishav Garg,Samson I. Eze,Emeka Chima Ogoko,Henrietta Ijeoma Kelle,Richard Alexis Ukpe,Raphael Ogbodo,Favour Chijoke Techno-Press 2023 Advances in nano research Vol.15 No.1
Nanoparticles are known for their outstanding properties such as particle size, surface area, optical and electrical properties. These properties have significantly boasted their applications in various surface phenomena. In this work, calcium oxide nanoparticles were synthesized from periwinkle shells as an approach towards waste management through resource recovery. The sol gel method was used for the synthesis. The nanoparticles were characterized using X-Ray diffractometer (XRD), Fourier Transformed Infra-Red Spectrophotometer (FTIR), Brunauer Emmett Teller (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and ultra violet visible spectrophotometer (UV-visible). While DLS and SEM underestimate the particle diameter, the BET analysis reveals surface area of 138.998 m<sup>2</sup>/g, pore volume = 0.167 m<sup>3</sup>/g and pore diameter of 2.47 nm. The nanoparticles were also employed as an adsorbent for the purification of dye (methyl orange) contaminated water. The adsorbent showed excellent removal efficiency (up to 97 %) for the dye through the mechanism of physical adsorption. The adsorption of the dye fitted the Langmuir and Temkin models. Analysis of FTIR spectrum after adsorption complemented with computational chemistry modelling to reveal the imine nitrogen group as the site for the adsorption of the dye unto the nanomaterials. The synthesized nanomaterials have an average particle size of 24 nm, showed a unique XRD peak and is thermally and mechanically stable within the investigated temperature range (30 to 70 ℃).
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Influence of pozzolans on properties of cementitious materials: A review
Garg, Rishav,Garg, Rajni,Eddy, Nnabuk Okon Techno-Press 2021 Advances in nano research Vol.11 No.4
Use of additives/supplementary materials in partial substitution of cement is gaining widespread attention across the world due to the sustainability issue with production of cement. With their pozzolanic activity & filler effect, use of nano-pozzolans such as nano-silica has been proved as quite promising & cost-effective for use as supplementary cementitious materials. This study is aimed at highlighting the effect of partial substitution of cement/addition of various nano-pozzolans on the hydration, strength and microstructure of the cementitious materials. Further, the effect of incorporation of other pozzolans has also been discussed. Comparative account of pozzolanic activity of different pozzolans has also been critically analyzed. It has been found that the cement matrix gets improved in terms of its microstructure by partial substitution of cement/addition of pozzolan in appropriate amount resulting in enhancement of the bulk properties by consumption of portlandite. The improved compressive strength of cementitious materials not only results in enhancement of the durability but also the service life of the construction structures and results in reduction of the cost incurred in maintenance and repair. Thus, the cement demand can be decreased by the partial substitution of cement/addition of such materials. It will result in an ultimate reduction of the greenhouse effect and lead to sustainable development.
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