Synthesis and Characterization of Greener Ceramic Materials with Lower Thermal Conductivity Using Olive Mill Solid Byproduct

In the current research, the valorization of olive mill solid waste as beneficial admixture into clay bodies for developing greener ceramic materials with lower thermal conductivity, thus with increased thermal insulation capacity towards energy savings, is investigated. Various clay/waste mixtures were prepared. The raw material mixtures were characterized and subjected to thermal gravimetric analysis, in order to optimize the mineral composition and maintain calcium and magnesium oxides content to a minimum. Test specimens were formed employing extrusion and then sintering procedure at different peak temperatures. Apparent density, water absorption capability, mechanical strength, porosity and thermal conductivity were determined on sintered specimens and examined in relation to the waste percentage and sintering temperature. The experimental results showed that ceramic production from clay/olive-mill solid waste mixtures is feasible. In fact, the mechanical properties are not significantly impacted with the incorporation of the waste in the ceramic body. However, the thermal conductivity decreases significantly, which can be of particular interest for thermal insulating materials development. Furthermore, the shape of the produced ceramics does not appear to change with the sintering temperature increase

Movement-based subgrouping in low back pain: synergy and divergence in approaches

Background Classification systems for low back pain (LBP) aim to guide treatment decisions. In physiotherapy, there are five classification schemes for LBP which consider responses to clinical movement examination. Little is known of the relationship between the schemes

Synergistic Sintering of Lignite Fly Ash and Steelmaking Residues towards Sustainable Compacted Ceramics

The development of value-added ceramic materials deriving only from industrial by-products is particularly interesting from technological, economic, and environmental point of views. In this work, the synergistic sintering of ternary and binary mixtures of fly ash, steelmaking electric arc furnace dust, and ladle furnace slag for the synthesis of compacted ceramics is reported. The sintered specimens’ microstructure and mineralogical composition were characterized by SEM-EDS and XRD, respectively. Moreover, the shrinkage, apparent density, water absorption, and Vickers microhardness (HV) were investigated at different sintering temperatures and raw material compositions. The characterization of the sintered compacts revealed the successful consolidation of the ceramic microstructures. According to the experimental findings, the ceramics obtained from fly ash/steel dust mixtures exhibited enhanced properties compared to the other mixtures tested. Moreover, the processing temperature affected the final properties of the produced ceramics. Specifically, a 407% HV increase for EAFD and a 2221% increase for the FA-EAFD mixture were recorded, by increasing the sintering temperature from 1050 to 1150°C. Likewise, a 972% shrinkage increase for EAFD and a 577% shrinkage increase for the FA-EAFD mixture were recorded, by increasing the sintering temperature from 1050 to 1150°C. The research results aim at shedding more light on the development of sustainable sintered ceramics from secondary industrial resources towards circular economy

Isotopic Grand Unification with the Inclusion of Gravity (revised version)

We introduce a dual lifting of unified gauge theories, the first characterized by the isotopies, which are axiom- preserving maps into broader structures with positive-definite generalized units used for the representation of matter under the isotopies of the Poincare' symmetry, and the second characterized by the isodualities, which are anti-isomorphic maps with negative-definite generalized units used for the representation of antimatter under the isodualities of the Poincare' symmetry. We then submit, apparently for the first time, a novel grand unification with the inclusion of gravity for matter embedded in the generalized positive-definite units of unified gauge theories while gravity for antimatter is embedded in the isodual isounit. We then show that the proposed grand unification provides realistic possibilities for a resolution of the axiomatic incompatibilities between gravitation and electroweak interactions due to curvature, antimatter and the fundamental space-time symmetries.Comment: 20 pages, Latex, revised in various details and with added reference

Synthesis and Characterization of Nickel-Alumina Composites from Recycled Nickel Powder

The recycling of metallic waste to create more valuable materials and their valorization into upgraded metal-based composites constitutes an important field of study. The composite industry nowadays considers environmental improvements as important as other properties of the materials. In the present paper, nickel powder was recycled from ferrous scrap, a low-cost and largely available material, by an effective hydrometallurgical recovery process. Then, this recycled powder was successfully used along with particulate α-alumina to prepare oblong nickel-based composite specimens with ceramic reinforcement loadings ranging from 0 to 30 wt.% by applying powder processing manufacturing techniques including cold isostatic pressing (CIP) and sintering. The microstructures obtained were characterized, the specimens were subjected to three-point bend tests, and their fracture behaviour was evaluated. By increasing the % ceramic reinforcement content, density clearly decreases while strengthening is achieved, thus leading to development of lightweight and enhanced oblong nickel-alumina composites. The composite microstructure, and particularly the metal-ceramic interface bonding, has a strong impact on fracture behaviour upon external loading

Decolorization kinetics of Procion H-exl dyes from textile dyeing using Fenton-like reactions

The decolorization kinetics of three commercially used Procion H-exl dyes was studied using a Fenton-like reagent. The effect of the major system parameters (pH, concentration of H2O2 and Fe3+ and initial dye concentration) on the kinetics was determined. For comparison, the effect of the use of UV irradiated Fenton-like reagent and of Fenton reagent on the kinetics was also examined. In addition, mineralization rates and the biodegradability improvement as well as the effect of the addition of Cl-, Co-3(2-) or HCO3- on the decolorization rates was studied. The reactions were carried out in a 300 ml stirred cylindrical reactor with the capability of UV irradiation. The dye half-life time goes through a minimum with respect to the solution pH between 3 and 4. It also exhibits a broad minimum with respect to Fe3+ and H2O2 at molar ratios of H2O2/Fe3+ from about 100 to 10. The addition of CO32- and HCO3 substantially reduces the decolorization rates, while this effect is significantly less pronounced with Cl-. At an optimum range of parameters, the mineralization rate (TOC reduction) is very slow for the Fenton-like process (TOC decrease from an initial 49.5 to 41.1 mg/l after 30 min and to only 35.2 mg/l after 600 min), but it increases significantly for the photo-Fenton-like process (to TOC values of 39.7 and 11.4 mg/l, respectively). The biodegradability, as expressed by the BOD/COD ratio, increases significantly from an initial value of 0.11-0.55 for the Fenton-like and to 0.72 for the photo-Fenton-like processes. (c) 2005 Elsevier B.V. All rights reserved

Development of reliable building bricks incorporating olive-mill wastewater focusing on thermal insulation and energy savings

The present communication reports the development of reliable building bricks with improved thermal insulation behavior through substitution of the water mixed with the standard ceramic clayey raw materials with olive-mill wastewater (OMWW). This endeavor will contribute to circular economy and environmental protection as well as possible energy savings and CO2 emission reductions. OMWW is an aqueous by-product generated in large amounts during olive oil production processes. It is characterized by high COD values, low biodegradability, high toxicity, acidic pH, a high concentration of potassium and high solid matter content. Therefore, finding eco-friendly and economically viable solutions for OMWW treatment and valorization represents a significant challenge in the oilproducing countries, in order to avoid severe environmental problems from the uncontrolled disposal of this effluent. For that purpose, a series of ceramic brick specimens are fabricated with the introduction of either olive-mill wastewater or water employing a pilot-plant simulation of the industrial brick manufacturing procedures. The brick thermal conductivity and the mechanical performance are evaluated. According to the results obtained the replacement of fresh water by olive-mill wastewater in the ceramic manufacturing provides a production of lighter building bricks of a decreased thermal conductivity (hence increased thermal insulation capability) as well as an acceptable and a reliable mechanical strength. Furthermore, the energy consumption measurements reveal energy savings of as much as 30 % attained during the brick firing. © 2019, University of Chemical Technology and Metallurgy

Effect of system parameters and of inorganic salts on the decolorization and degradation of Procion H-exl dyes. Comparison of H2O2/UV, Fenton, UV/Fenton, TiO2/UV and TiO2/UV/H2O2 processes

Reactive dyes are extensively used in the last years due to their superior performance, but they are environmentally hazardous. In the present work, the decolorization and degradation of commercial reactive azo dyes (Procion Navy H-exl, Procion Crimson H-exl and Procion Yellow H-exl) were studied using five advanced oxidation processes (AOPs): H2O2/UV, Fenton, UV/Fenton, TiO2/UV and TiO2/UV/H2O2. The dependence of the decolorization on the system parameters (solution pH, dye and reactants initial concentrations, and TiO2 loading) and on the presence of salts (NaCl, Na2CO3, NaHCO3, Na2SO4, NaNO3 and Na3PO4) was investigated. The decolorization (determined by spectrophotometric analysis) and the degradation (determined as TOC reduction) were compared for the different processes examined. The decolorization of the Procion H-exl solutions considered was found to strongly depend on the system parameters in all five AOPs. Although decolorization is very fast for the Fenton process and becomes even faster for the UV/Fenton process, degradation rates are relatively low for these two methods. Addition of H2O2 increases the decolorization and especially the degradation rates for the TiO2/UV process. The H2O2/UV and TiO2/UV/H2O2 processes result in the fastest dye degradation. The addition of the salts examined has in general an adverse effect on the decolorization rates, but to a varying degree depending on the salt used