A holistic multi-methodology for sustainable renovation

A review of the barriers for building renovation has revealed a lack of methodologies, which can promote sustainability objectives and assist various stakeholders during the design stage of building renovation/retrofitting projects. The purpose of this paper is to develop a Holistic Multi-methodology for Sustainable Renovation, which aims to deal with complexity of renovation projects. It provides a framework through which to involve the different stakeholders in the design process to improve group learning and group decision-making, and hence make the building renovation design process more robust and efficient. Therefore, the paper discusses the essence of multifaceted barriers in building renovation regarding cultural changes and technological/physical changes. The outcome is a proposal for a multi-methodology framework, which is developed by introducing, evaluating and mixing methods from Soft Systems Methodologies (SSM) with Multiple Criteria Decision Making (MCDM). The potential of applying the proposed methodology in renovation projects is demonstrated through a case study

Effects of concurrent TeO2 reduction and ZnO addition on elastic and structural properties of (90 − x)TeO2–10Nb2O5–(x)ZnO glass

Niobium-containing tellurite glass with starting composition of (90 − x)TeO2–10Nb2O5–(x)ZnO (x = 0–15 mol%) have been prepared by melt-quenching method and the effect of reduction of TeO2 with simultaneous increase in ZnO on elastic properties was studied. Ultrasonic longitudinal and shear velocity showed initial decrease of 3.52% and 2.37%, respectively, at x = 5 mol%. For x > 5 mol%, longitudinal velocity showed weak recovery but shear velocity showed steady recovery with ZnO and recorded 0.95% increase in value at x = 15 mol% compared to x = 0 sample. Shear and Young's moduli recorded similar drop at x = 5 mol% followed by strong recovery at x > 5 mol%, while longitudinal and Bulk modulus showed weak and no recovery, respectively, with x. Infrared (IR) absorption spectra showed increase in intensity of NbO6-assigned peak accompanied by increase in intensity of ZnO4 tetrahedra and TeO4 trigonal bipyramid (tbp) assigned peaks indicating formation of both non-bridging oxygen, NBO and bridging oxygen, BO, respectively, with addition of ZnO. The initial drop in ultrasonic velocity and related elastic moduli observed at x = 5 mol% indicates weakening of network rigidity of the glass system due to structural modification as a direct effect of TeO2 reduction and existence of NBO. However, further replacement of TeO2 by ZnO at x > 5 mol% contributed to increase in BO causing rigidity of the glass network to improve. In addition, hardness, H, was observed to increase with ZnO indicating increase in connectivity of the glass network while Poisson's ratio, σ, decreased indicating increase in cross-link density of the glass system. The combined results of ultrasonic velocity and IR absorption spectra suggest that the role of TeO2 is very critical in the ternary glass system as, although ZnO addition showed improved rigidity due to recovery of shear modulus, the weakening of longitudinal and Bulk moduli indicates ZnO is not fully effective as glass former in place of TeO2

Optical performance of neodymium nanoparticles doped tellurite glasses

A series of neodymium NPs doped tellurite glass with composition of (TeO2)0.7(B2O3)0.3]0.7 (ZnO)0.3}1- x (Nd2O3 NPs) x (x = 0.005, 0.01, 0.02, 0.03, 0.04 and 0.05 mol%) was fabricated via melt-quenching method. Density and molar volume were measured and analyzed for the glass series. The optical properties of neodymium NPs doped tellurite glass were measured by UV–Vis spectrometer, photoluminescence and Z-scan technique. The optical band gap energy of the glass network was in the range of 3.178–3.209 eV. The upconversion emission of the laser glass excited at 800 nm was found in the ultraviolet region. Electronic polarizability, oxide ion polarizability, optical basicity and metallization criterion were calculated. Moreover, linear absorption coefficient, α, nonlinear refractive index ƞ (cm2/W), nonlinear absorption, β (x 10−3) and third order susceptibilities, χ (x 10−6) were measured. The optical efficiency of neodymium NPs doped tellurite glass exhibited excellent properties for its application in laser glass

A review of nano-based materials used as flocculants for water treatment

In recent years, the development of nanoparticle materials for water treatment has received great attention. From an industrial technological view point, the application of nanomaterials in the twenty-first century for water treatment will be the focal point of advanced materials design, processing and progress. In this context, the potential utilisation of different types of flocculants to clean up contaminated water becomes important to address the tremendous increase of water pollution resulting from continued high-level global industrialisation. A number of researchers have investigated the effectiveness of various nanoflocculants for this purpose. Although these nanoflocculants have been reported to successfully treat contaminated water, their flocculation performances are different. To the best of our knowledge, there is no review article which summarises the application and performance of nanoflocculants in the treatment of water containing various types of contaminants. This review summarises the recent development of a wide range of nanoflocculants for the treatment of water polluted particularly by heavy metals, dyes and bacteria. The influence of physicochemical properties of nanoflocculants upon their performance and optimum flocculation conditions is discussed in detail. This review will provide a useful source of information for researchers working on the advancement of cost-effective and environmentally friendly nanoflocculants

Effect of samarium nanopeprintss on optical properties of zinc borotellurite glass system

he glass series of samarium nanoparticles (NPs) doped zinc borotellurite glasses were successfully fabricated by using conventional melt-quenching technique. The structural properties of the prepared glasses were investigated by X-ray diffraction (XRD) analysis and FTIR analysis. It was confirmed that the prepared glasses are amorphous in nature. The bonding parameters of the glasses were analyzed by using FTIR analysis and were found the formation of non-bridging oxygen. The density of these glasses were measured and found to be increased with increasing samarium NPs content. The optical absorption spectra of these glasses were revealed that the fundamental absorption edge shifts to higher wavelengths as the content of Sm2O3 (NPs) increases. The optical energy band gap are found to be decreased linearly with an increasing samarium NPs concentration which is due to the formation of non-bridging oxygen in the glass system.KeywordsBorotellurite glass; optical band gap, Samarium nanoparticles

Optical properties of ternary TeO2-B2O3-ZnO glass system.

A series of ternary tellurite based glasses [(TeO2)70 (B203)30]100-x [ZnO]x glasses with different compositions of ZnO (x= 5 to 30 wt.% in steps of 5 wt.%) have been synthesized by melt quenching method. The role of ZnO to the glasses structure was studied by IR spectroscopy. FTIR spectra revealed broad, weak and strong absorption bands in the investigated range of wavenumber from 280-4000 cm-1 which associated with their corresponding bond modes of vibration and the glass structure. The indirect optical band gap and the direct optical band gap are in the range 2.08-3.12 and 1.54-2.36 eV, respectively. A decrease in the values of energy band gap Eg may come down to the reason that the non-bridging oxygen ion content increases with increasing ZnO content and shifting the band edge to lower energies. The optical band gap and Urbach energies were calculated from the absorption spectra measured between 190 and 900 nm at room temperature. The refractive index, n of the glasses change from 1.84-2.00 while the molar refractivities decrease from 13.06 to 12.00 with the increase of ZnO in mol%

Influence of erbium oxide on structural, physical, elastic and luminescence properties of rice husk biosilicate zinc borotellurite glasses for laser application

Nowadays, active search for more efficient and improved glass material to be employed as laser host has been take place in order to have laser with enhanced performance. In this research, erbium oxide doped rice husk biosilicate zinc borotellurite glasses have been fabricated successfully via conventional melt quenching technique. XRD pattern reveals that the prepared glasses are amorphous in nature while FTIR spectra records the presence of Si-O-Si, TeO3, BO4 as well as BO3 vibrational groups in the fabricated glasses. Increasing density from 3.3505 g/cm3 to 4.1852 g/cm3 along with the rigidity of the glass as hinted in the values for elastic moduli from 55.0 GPa to 250.0 GPa is caused by the incorporation of erbium oxide that reduce the amount of non-bridging oxygen in the glass matrix. Three bands that are recorded in PL spectra correspond to the violet, blue and green emission

Enhanced optical performance of tellurite glass doped with samarium nanoparticles for fiber optics application

We report on the optical efficiency of samarium nanoparticles (NPs) doped tellurite glasses experimentally, for the first time to the best of our knowledge. A high optical efficiency of samarium NPs doped tellurite glasses stable against crystallization was fabricated via melt- quenched technique. In particular, this work underlines the enhancement of optical properties with increasing samarium NPs concentration and the change of polarizability of tellurite glass network with the presence of samarium NPs. Using X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) analysis and transmission electron spectra (TEM), the amorphous arrangement, structural assignments and particle size had been revealed. The optical performance of samarium NPs doped tellurite glass was characterized by EL X-02C high accuracy ellipsometer and UV-Vis spectrophotometer. Based on ellipsometer and UV-Vis spectrophotometer, the refractive index was found slightly increases meanwhile the optical band gap is reduced with the presence of samarium NPs. The obtained value of electronic polarizability revealed that samarium NPs affect greatly on polarizability of tellurite glass network. The slightly increases and nonlinear variations of polarizability were found with increasing amount of samarium NPs. The metallization criterion was found to decreased which suggest that the samarium NPs doped tellurite glass tends to be more semiconductor. This is a first step towards high optical performance of tellurite glass with future applications in fiber optics and laser glass

Study of rice husk silicate effects on the elastic, physical and structural properties of borotellurite glasses

Successful extraction of high purity SiO₂ (about 99%) from rice husk (waste) was achieved in this work using the cold acid leaching method. Glass series [(TeO₂)0.₇ (B₂O₃)0.₃]1-x (SiO₂)x were fabricated using the rice husk silicate (RHS) by melt-quenching method. The samples were subjected to X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) characterization to study the structural nature of the glass system. Density and ultrasonic velocities were measured to obtain the elastic constants for the various silicate proportions in the glass using ultrasonic data obtained from non-destructive ultrasonic probing technique. The elastic moduli calculated from the obtained data were found to have increased with the addition of more RHS in the glass. Other parameters studied include the microhardness (H), Poisson's ratio (σ), softening temperature (ϴD) and fractal bond connectivity (d) and the fluctuation free volume (fugacity, fg). A very unusual occurrence was observed as microhardness value decreases in the glass system as more RHS (SiO₂) is introduced. The quality of the glass in terms of elastic behavior improved with addition of RHS in the borotellurite glass network

Graphene oxide deposition on neodymium doped zinc borotellurite glass surface: optical and polarizability study for future fiber optics

Neodymium oxide doped tellurite-based glass has been widely documented for potential uses in optoelectronics, but graphene oxide (GO)-coated tellurite-based glass has rarely been reported. In this work, we compare two sets of glass series which were GO-coated and uncoated tellurite-based glass series denoted as ZBTNd-GO and ZBTNd, respectively. The two sets of glasses were fabricated via melt-quenched process. A set of glass was coated with GO using low-cost spray coating method. The structural and morphological properties of the glass samples were investigated to confirm the type of structure in glass and formation of graphene oxide on glass surface. The X-ray diffraction (XRD) pattern confirmed the amorphous structural arrangement in both sets of glass series. The morphological study proved the existence of GO layers on top of the ZBTNd-GO surface. The optical bandgap energy of ZBTNd-GO glass was found in the range of 3.253 eV–3.381 eV which was higher than ZBTNd glass. Meanwhile, the refractive index of ZBTNd-GO glass varies from 2.301 to 2.332 which was higher than ZBTNd glass due to the presence of functionalized oxygenated groups in GO structure. The oxide ion polarizability of ZBTNd-GO glass was found decreased due to the shift of optical band gap when coated with GO. This work offers a new form of glass that could be used as a new strategy to upgrade the current photonic materials