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This research studies the effects of composition and granulometry analysis of 139 heavy clays on the important characteristics of wet and adobe clay bricks. ANN models were obtained with high prediction accuracy in training cycles (r(2)): 0.580-0.907. Standard score analysis (SS) is performed to evaluate the optimal content of raw materials to gain adobe bricks. Optimal macro-oxides content was 53-66% SiO2, 4.6-7.5% Fe2O3, 12.5-18.2% Al2O3, 0.9-8.8% CaO, 1.2-3.6% MgO. The optimal quantity of alevrolite-sized particles varied between 46 and 65%, and clay-sized particles contents ranged from 20.4 to 40.6%.

The surface sediments sampled from forty sampling sites in the Boka Kotorska Bay, starting from October 2005 to December 2019, were analysed for the content of ten heavy metals (As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Zn, Fe). Five complex indices (pollution load index (PLI), potential ecological risk index (RI), mean ERM quotient (MERMQ), toxic risk index (TRI), contamination severity index (CSI)) were determined for each site in the study period (2005, 2007, 2013, 2019), and statistically examined by principal component analysis (PCA) and cluster analysis (CA). In the semi-enclosed Bay, which consists of four smaller bays (Kotor, Risan, Tivat, Herceg Novi bays), a spatio-temporal comparison of sediment quality was carried out using PCA and CA analysis of the considered pollution indices. Statistical results revealed that the increased environmental risk in 2005 was observed in the bay of Kotor; in 2007 was in the bay of Tivat and Risan; in 2013 in the bay of Kotor and Tivat; and in 2019 was in the bay of Tivat, particularly at the shipyard site Bijela. The PCA and CA analysis highlighted that the sediment contamination in Kotor bay decreased from 2005 to 2019, while at the same time increased in Tivat bay, which is an indication of pollution due to urbanization and population growth in this part of the Bay. The results gave a statistical overview of the similarities between the pollution indices and the differences in the degree of sediment pollution in the Bay during the last two decades.

In this paper, the main subject concerns comparing different techniques to prepare raw clay samples for energy-dispersive X-ray fluorescence spectrometry (EDXRF). Three kinds of sample preparation procedures are examined, such as loose powder, pressed pellet, and fired pressed pellet. The fired pressed pellet approach was observed as a part of universal sample preparation for physic, mechanical, and instrumental analysis, which has not been previously tested as a solution in chemical analysis by the EDXRF method. The observed sample preparation techniques were compared by calculating the parameters of validation (recoveries, limit of detection - LOD, limit of quantification - LOQ, precision, and expanded uncertainties of measurements) of 11 elements (Si, Al, Fe, Ca, Mg, K, Na, Ti, P, Mn, and S) using 15 certified reference materials (CRMs). Calibration curves were created and evaluated using 30 reference materials (RM) for all three approaches. Results proved that the fired pressed pellet is the most practical and precise approach for sample preparation of raw clays.

In recent years, thermal decomposition studies of transition metal complexes with benzenepolycarboxylate ligands have become an area of a great importance due to the possibility of obtaining useful metal oxides with desirable electrical, magnetic and catalytic properties [1]. As a contrast to conventional methods for the preparation of metal oxides, such as hydrothermal or sol– gel treatment, thermolysis is faster, more efficient and environmentally friendly. Mn(II)–dipya (dipya = 2,2’-dipyridylamine) complex with tetraanion of 1,2,4,5-benzenetetracarboxylic (pyromellitic, H4pyr) acid, [Mn2(dipya)2(pyr)(H2O)2], has been prepared and characterized by elemental, spectral and microscopy analyses. Direct thermolysis of the complex up to 1200 °C in an air atmosphere yielded spinel Mn3O4 oxide material. The obtained Mn3O4 has been characterized for its structural, spectroscopic, morphological and optical properties. The possibilities of using this oxide as photocatalyst or co-photocatalyst for removing textile organic dyes, as well as inorganic pigmentary material, were also investigated and discussed.

Due to rapid urbanisation, urban microclimate research has become increasingly popular in the last decade. Significant variation in microclimate conditions can be created due to diversity in urban geometry and it can affect outdoor thermal comfort. Biometeoro-logical measurements and survey were conducted in different urban settings (square, park, street) of the city of Novi Sad during a warm autumn day in October 2019. Air temperature, relative humidity, wind speed and globe temperature, but also outdoor thermal comfort indices such as Mean Radiant Temperature (Tmrt) and Physiological Equivalent Temperature (PET) were obtained for each location. The largest differences in the biometeorological conditions are noticed between the urban park and other urban areas. The maximum average value of Ta was at the city square with 27.9oC, while in the urban park and street Ta were about 25oC. The values of RH were the lowest at the city square. Globe temperature (Tg) had the highest values, on average, at the city square (about 40oC), while the average values in the urban park and street were about 26–28oC. The highest average PET values are registered at the city square (41.4oC), followed by substantially lower average PET registered in urban park (27.1oC) and urban street canyon (26.2oC). The analysis showed that during about 70% of the time, urban dwellers experience extreme heat stress at the city square. Contrary to that, no extreme heat stress is noticed in urban park and street canyon.

The industrial raw material compositions in brick or tile production are normally adapting from time to time with novel clays. The proper raw material change must be based on the reliable raw material characterization tests. Regardless to the fact that commonly used (Bigot, Muller- Biehl, Ratzenberger, Piltz, Hermansons, etc.) drying sensitivity criterions allow the comparison of different raw materials they are not related with the mineral composition and mechanical nature of clays. Besides these are timedemanding tests. The X-ray characterization of raw material is reliable only when orientated samples are prepared. In other cases, it is necessary to have additional characterization test such as thermo-differential (DTA) and thermo-gravimetric (TG) analysis in order to confirm the presence or absence of individual clay minerals. The quantity of the interlayer water content present in clays is in direct correlation with the mineralogical composition and the clay type. This effect can be easily qualified on the DTA/TG curves. This was a trigger for establishing the novel rapid drying sensitivity criteria. The analysis of different raw materials has confirmed that the moisture loss registered on TG curves at 2000C can be used as novel drying sensitivity criterion. This value is respectively for insensitive raw materials less than 2.0 while for highly sensitive one is larger than 2.80. The proposed method is very simple, rapid and reliable for the application in brick and tile industry. The second objective of this paper was to compare the results of the proposed method with the widely used Bigoth, Ratzenberg and Piltz tests. A good correlation was found.

The usage possibility of 19 composites of raw refractory clays from Serbia containing approximately 53.29% of SiO2 and 26.73% of Al2O3 is presented. The sum of fluxing oxides was 57.74%, while these materials contained 32% of quartz, 29% of kaolinite and 26% of illite–mica. Dilatometry tests revealed a sudden shrinkage with the peak at approximately 1115 °C, owing to the formation of mullite. The refractoriness was in the range of 1581–1718 °C, which classifies the composites from low- to high-duty refractories. Based on correlation analysis, the refractoriness mostly depended on the content of alumina. The lightness of the fired test pieces was lower after firing when compared to the dry samples, and it decreased with the firing temperature from reddish to grayish. The study presents a novel attempt to define all the necessary properties of raw refractory clays and products fired at the 1100–1300 °C range on a laboratory level. Most of these clays can be used as natural refractory materials for ceramic and glass furnace lining. The organic matter in some of the samples influences negatively the fast-firing process.

A biphasic [Mn(dipya)(H2O)4](tpht)/{[Zn(dipya)(tpht)]·H2O}n complex material, I, (dipya = 2,2’-dipyridylamine, tpht2– = dianion of terephthalatic acid) was synthesized by ligand exchange reaction and characterized by XRPD and FTIR spectroscopy. A ZnO/ZnMn2O4 composite, II, has been prepared via thermal decomposition of precursor I in an air atmosphere at 450 °C. XRPD, FTIR and FESEM analyses of II revealed the simultaneous presence of spherical nanoparticles of wurtzite ZnO and elongated nanoparticles of spinel ZnMn2O4. The specific surface area of II was determined by the BET method, whereas the volume and average size of the mesopores were calculated in accordance with the BJH method. The measurements of the mean size, polydispersity index and zeta potential showed colloidal instability of II. Two band gap values of 2.4 and 3.3 eV were determined using UV–Vis diffuse reflectance spectroscopy, while the measurements of photoluminescence revealed that II is active in the blue region of the visible spectrum. Testing of composite II as a pigmentary material showed that it can be used for the colouring of a ceramic glaze.

Geopolymerization was investigated as an alternative to traditional ceramic products by developing a more sustainable approach that avoids thermal treatment. The study presents the first known alkali-activation of the raw clay and waste clay brick mixture using the solid to liquid ratios of 2.33 and 2.78. Several experimental sets were prepared to harden under varying conditions (2–4 days drying in 60 °C–70 °C and 3 h steam-curing). Non-activated and activated samples were analyzed for their physical and chemical properties after 14, 21, and 28 days. The tile-shaped specimens exhibited better initial drying behavior than the cubes and produced stronger materials with fewer cracks. Pre-curing in steam conditions induced higher flexural strength (13.7 MPa) and water absorption (13.13%) for the geopolymer tiles. The highest Si/Al molar ratio in the amorphous portion of 5.78 induced the best flexural strength. The geopolymerization process showed microstructural changes associated with the appearance of fibrous Na-zeolite nanocrystals. The degree of geopolymerization and zeolite formation was enhanced by steam-curing, but the microstructural stress and heterogeneity induced by the reactions resulted in higher water absorption. Ongoing reactions of amorphization in the bulk material and further crystallization at the surface are documented after 6 months of curing. This first detailed study reveals that the production of geopolymer ceramics from brick waste is possible, but further optimization of the activating solution and curing parameters is required.

APSTRAKT: U ovoj disertaciji su prikazani rezultati ispitivanja legure Fe72Cu1V4Si15B8, koja pripada familiji FINEMET-tipa legura. Legura je izrađena ultrabrzim hlađenjem rastopa legure na rotirajućem disku. Dobijena legura ima već formirane nanokristalne faze (α-Fe(Si) i Fe23B6 faze), koje se nalaze u amorfnoj matrici, što je ustanovljeno XRD analizom i Mesbauerovom spektroskopijom. Pored toga, Mesbauerovom spektroskopijom je ustanovljeno postojanje znatno više kristalnih faza koje zbog male zastupljenosti nisu detektovane XRD analizom. Legura je termički tretirana, što je indukovalo strukturne promene koje su doprinele promeni magnetnih svojstava. DTA analizom je legura zagrevana do 1073 K, različitim brzinama (β= 5K/min, 10K/min i 20 K/min), kojom su ustanovljena dva kristalizaciona pika: (i) od 750 K do 780 K i (ii) od 875 K do 900 K (za β= 5 K/min). Oba pika su nesimetrična, što ukazuje na složenost procesa kristalizacije. Ovi pikovi odgovaraju jednom termomagnetnom piku u intervalu od 745 K do 875 K (za H=7960 A/m i β= 4 K/min). Termomagnetnim merenjima je ustanovljena Kirijeva temperatura amorfne faze legure koja iznosi oko 615 K i Kirijeva temperatura iskristalisane legure koja iznosi oko 875 K. Nakon toga su uzorci oblika trake odgrevani različitim temperaturama (Tan= 573 K – 973 K). Ustanovljeno je da je pri Tan= 773 K došlo do najvećeg povećanja magnetizacije zasićenja, Ms uz minimalno povećanje koercitivnog polja, Hc. Povećanje Ms se objašnjava uvećanjem zastupljenosti α-Fe(Si) faze, sa porastom Tan, usled transformacije amorfne u kristalnu fazu. Prosečna veličina novoformiranih kristalita α-Fe(Si) faze ista je kao i veličini kristalita u neodgrevanoj leguri do Tan=773 K. Pri Tan>773 K dolazi do naglog povećavanja prosečne veličine kristalita ove faze, što uzrokuje slabiju pokretljivost magnetnih domena, zbog čega se smanjuje Ms. Isti trend promena Ms uočen je i za longitudinalnu i normalnu (perpendikularnu) orijentaciju uzorka u magnetnom polju u odnosu, This dissertation presents the results of examination of the alloy Fe72Cu1V4Si15B8, which belongs to the FINEMET-type family of alloys. The alloy was prepared with a rapid quenching of the melt on a rotating disc. The as-prepared alloy already contains nanocrystals of α-Fe(Si) and Fe23B6 phases, in an amorphous matrix, that is observed by XRD analysis and by Mössbauer spectroscopy. In addition, Mössbauer spectroscopy revealed the existence of significantly more crystal phases that, due to their low presence, were not detected by XRD analysis. The alloy was thermally treated, which induced structural changes that contributed to the changes in magnetic properties. First, the alloy was heated to 1073 K, at different rates (β = 5K/min, 10K/min and 20 K/min), and two crystallization peaks were found by DTA analysis: (i) from 750 K to 780 K, and (ii) from 875 K to 900 K (for β = 5 K/min). Both peaks are asymmetric, which indicates the complexity of the crystallization process. These peaks correspond to a single thermomagnetic peak in the range from 745 K to 875 K (for H = 7960 A/ m and β = 4 K/ min). Thermomagnetic measurements revealed the Curie temperature of the amorphous phase of the alloy at 615 K, and the Curie temperature of the crystallized alloy at 875 K. After that, the ribbon-shaped samples were annealed at different temperatures (Tan = 573 K - 973 K). It was found that at Tan = 773 K there was the huge increase in saturation magnetization (Ms) with a minimal increase in the coercive field (Hc). The increase in Ms is explained by the increase of the abundance of α-Fe (Si) phase, with the increase of Tan, due to the transformation of amorphous into crystalline phase. The average size of the evolved crystallites of α-Fe (Si) phase is the same as the size of crystallites in the as-prepared alloy up to Tan = 773 K. At Tan > 773 K there is a sharp increase in the average size of crystallites of this phase, which causes slow mobility of magnetic domains due

The nanocomposite samples, containing copper and iron species in the silica matrix, were prepared by annealing at temperatures up to 1100°C. The samples were investigated by X-ray diffraction analysis, Fourier transform infrared spectroscopy, and cyclic voltammetry. The results of the performed study depict to the presence of a temperature gradient, which acts on the sample during the annealing treatment in the furnace. For the first time, the influence of the temperature gradient on the formation mechanism of the samples was discussed. © 2021, Pleiades Publishing, Ltd.

Drying has an enormous impact on the quality of final masonry clay elements. The accumulated knowledge about modeling the drying process, as well as the registered progress in computing the coupling between the heat and mass transfer during the last decade has reached the applicative industrial level. The available novel commercial drying solutions have dropped the drying cycle to 5 hours for hollow clay products and up to 9 hours for clay blocks of large size and weight. The ability to speed up the drying process also strongly depends on the properties of the raw materials. The decision on optimization of the existing dryer and its upgrade or investment in a novel drying facility must be experimentally validated. Results of the one-month monitoring and analysis of the production process in one Serbian brick factory including the material and energy balances are given in this paper. Based on the collected data, raw material limitations and costs of the novel dryer the existing tunnel dryer upgrade and the minimization of the "false" ambient air into the dryer are proposed.

The main idea of this research was to evaluate rice and sunflower hulls, sawdust and their ashes, as additives in clay brick production using mathematical analysis. All available papers, containing the parameters of interest, were used in the study, which consisted of total 316 cases, obtained from the literature. The major oxide content of clays and mixtures, then weight percent addition and particle size ranges of secondary raw materials, and process parameters (firing temperature, soaking time and average heating rate) were selected as inputs to mathematical models. Shaping moist was the only parameter characterizing transition state of the products analyzed as an output parameter. The other parameters described the fired product quality: linear shrinkage, bulk density, water absorption, compressive and bending strength. The main goal was to find the relationships and the main influences between raw material properties, process parameters, and the quality of the obtained products and mixtures, by using mathematical tools. Statistical and mathematical analyses were applied for prediction of final product quality. Developed artificial neural network empirical models (ANNs) give a reasonable fit to experimental data and successfully predict the most of the observed output variables, showing the good prediction capabilities (coefficient of determination varied between 0.714 and 0.998). Sensitivity analysis showed that, among all the studied parameters concerning raw materials and process parameters, the dominant influence belonged to loss on ignition.

This research describes a study of 11 selected samples of brick clays applied in roofing tile production, by using simultaneous thermal analysis. Additionally, the laboratory-sized samples were prepared and fired (850-950 degrees C) and technological properties were determined. Mathematical analysis was applied to sum all the experimental results and help discriminate the samples by their behavior during firing. The samples, very similar according to mineralogical and chemical content, as well as granulometry tests, were successfully grouped using principal component analysis (PCA). The PCA was used to explore and easily visualize the differences between samples. The PCA performed for differential thermal analysis (DTA), differential scanning calorimetry (DSC) and differential thermogravimetry (DTG) curves clearly showed that the heat flow was mainly influenced by carbonate content and its grain size, while DTG discriminated samples according to the contents of clay minerals and carbonates. In addition, dilatometry analysis revealed which samples underwent the highest densification during the firing process. The PCA analysis of fired products properties showed that the highest correlations were between water absorption with firing shrinkage and compressive strength.

The aim of this study was to test montmorillonite and hydromica type of brick clays by using simultaneous thermal analysis and dilatometry in an assessment of the suitability of brick clays to produce building elements. The plasticity coefficient and drying susceptibility were determined to discover the behavior of brick clays. Fired products' characteristics were studied by performing water absorption and compressive strength tests. All the methods were employed in the construction of the firing curves in a tunnel kiln. The results could increase the degree of certainty to lead the production process towards obtaining the desired features of brick elements.

Nanocomposites (HAp/iron oxide), made of hydroxyapatite (HAp) and ferrimagnetic iron oxide, were synthesized by high-energy ball milling a mixture consisting of iron oxide nanoparticles and the starting materials used for the HAp synthesis: calcium hydrogen phosphate anhydrous (CaHPO4), and calcium hydroxide (Ca(OH)2). Two HAp/iron oxide samples with the magnetic phase content of 12 and 30 wt.% were prepared and their microstructure, morphology and magnetic properties were analysed by X-ray diffraction and transmission electron microscopy. Furthermore, the measurement of particle size distribution was performed by laser scattering, and temperature/field dependence on magnetization was determined. X-ray diffraction data confirmed the formation of two-phased samples (HAp and spinel iron oxide) without the presence of any other parasite phase. The shape of particles was nearly spherical in both samples, ranging from only a few to several tens of nanometres in diameter. These particles formed agglomerates with the most common value of the number-based particle size distribution of 380 and 310 nm for the sample with 12 and 30 wt.% of iron oxide, respectively. Magnetization data showed that both HAp/iron oxide composites had superparamagnetic behaviour at room temperature. © 2019 University of Novi Sad, Faculty of Technology. All rights reserved.

The goal of this study was the research on the usage capability of various industrial wastes in clay bricks. Changes in product's behavior were studied in terms of relative differences in ceramic-technological parameters compared to samples without waste materials addition. The effects of organic and inorganic wastes were investigated in terms of changes introduced to products during shaping, drying, and firing. Samples with coal dust addition showed the highest sensitivity to drying, whereas the greatest plasticity and shaping moist were detected in samples with 50 wt.% of fly and landfill ashes. Waste material addition quantities and firing temperatures were independent parameters that influenced dependent parameters such as compressive strength, water absorption, firing shrinkage, weight loss during firing, and volume mass. The optimization results demonstrated that sunflower hulls, wood sawdust, soybean husks, and saturation sludge are best to be used in solid-brick production. Coal dust, landfill ashes, and neutralization (inorganic) sludge are best to be used in hollow-brick production. Sunflower hulls ash can be added in higher quantity to heavy clay to produce blocks or in lower quantity in roof tiles. The addition of 50 wt.% fly ash allows production of roof tiles.

Istraživanje u okviru doktorske disertacije obuhvata uzorkovanja inhalativne frakcije praškastih materija generisane u zubotehničkoj laboratoriji i procesom brušenja čelika EN 90MnCrV8, primenu savremenih metodologija uzorkovanja, analizu uzorka laserskom difrakcijom i analizom slike, zasnovanom na mikrografijama skenirajućeg elektronskog mikroskopa i statističku obradu podataka. Osnovni cilj istraživanja je razvoj funkcionalnog modela za evaluaciju rezultata merenja karakteristika praškastih materija, koji je obuhvatio identifikaciju, procenu i vrednovanje karakteristika prahova, u cilju unapređenja tačnosti rezultata u vezi sa karakterizacijom čestica. Složena geometrija čestica je ispitana analizom 14 parametara, 6 koji definišu veličinu i 8 parametara koji opisuju morfološke karakteristike, upotrebom dva softvera za analizu slike. Dobijeni rezultati obrađeni su primenom metode analize glavnih komponenti i hijerarhijske klaster analize, čime se prevazišao problem subjektivnog prilaza i izvršila redukcija i selekcije reprezantativnih parametara na osnovu kojih se može dovoljno dobro definisati i okarakterisati uzorak., Тhis PhD thesis presented the development of the functional model for evaluation оf measuring results of powder materials’ characteristics, which involved the identification, assessment and evaluation of particles characteristics, in order to improve the accuracy of the results. Sampling of inhalation fraction of the powder materials’ was done in the dental laboratory and grinding process of the EN 90MnCrV8 steel. Particle analysis was performed whit laser diffraction and image analysis based on micrographics from scanning electron microscopy and data were statistically analyzed. The complex particle geometry was examined by analyzing 14 parameters, 6 which define the size and 8 parameters that describe the morphological characteristics, using two image analysis software. To deal with a large number of the numerical parameters used to characterise the particle geometry and the nonlinear relationships among these parameters, principal component analysis (PCA) and hierarchical cluster analysis (CA) algorithm was applied to identify representative numerical descriptors within each group.

U disertaciji je ispitana termička stabilnost pet kompleksa prelaznih metala (Cu, Ni i Zn) sa anjonima aromatičnih polikarboksilnih kiselina: ftalne (pht), izoftalne (ipht) i piromelitne (pyr) kiseline i različitim aminskim ligandima, kao što su etilendiamin (en), bipiridin (bipy) i 2,2'-dipiridilamin (dipya). Razmatrani kompleksi [Cu2(bipy)2(pht)2]·4H2O, Na2[Cu(pht)2]·2H2O, K2[Cu(pht)2]·2H2O, [Zn(dipya)(ipht)]n i [Ni2(en)2(H2O)6(pyr)]·4H2O sintetisani su reakcijom izmene liganada. Strukture kompleksa detaljno su opisane zajedno sa uporednom analizom strukturnih karakteristika. Posebna pažnja posvećena je načinu koordinacije odgovarajućeg polikarboksilato-jona i konformaciji karboksilat-grupa koji uslovljavaju različitu dimenzionalnost (0 – 2D) ispitivanih materijala..., Thermal stability of five transition metal (Cu, Ni and Zn) complexes containing the anions of aromatic polycarboxylic acids: phthalic (pht), isophthalic (ipht) and pyromellitic acid (pyr), and different amine ligands such as ethylenediamine (en), bipyridine (bipy) and 2,2'-dipyridylamine (dipya) was investigated. The examined complexes [Cu2(bipy)2(pht)2]·4H2O, Na2[Cu(pht)2]·2H2O, K2[Cu(pht)2]·2H2O, [Zn(dipya)(ipht)]n and [Ni2(en)2(H2O)6(pyr)]·4H2O were synthesized by ligand exchange reaction. Structures of the complexes are described in detail together with a comparative analysis of structural characteristics. Special attention has been devoted to the coordination mode of the corresponding polycarboxylato ion and the conformation of the carboxylate groups which cause the different dimensionality (0 – 2D) of the investigated materials...

NiA and NiX zeolites were prepared and characterised using XRD, FTIR and SEM, and subsequently tested as electrodes for hydrogen (HER) and oxygen (OER) evolution reactions in alkaline media. Linear sweep voltammetry and chronoamperometry techniques showed that NiA has higher catalytic activity for these two reactions, as evidenced by higher current densities, which can be correlated with a higher weight fraction of Ni in this electrocatalyst than in the NiX and with its higher conductivity. HER and OER kinetic parameters, including Tafel slope, exchange current density and apparent activation energy were evaluated. Electrochemical impedance spectroscopy analysis yielded values of the resistance of the solution, charge transfer and mass transfer, as well as double layer capacitance and pseudo-capacitance of the working electrode, at different potentials and temperatures. Unlike the HER, during which the mass transfer resistance of the adsorbed intermediate is dominant in the case of NiA, the OER impedance response is controlled by the charge transfer process itself at the potentials of interest for these process. The overall resistance related to the HER is lower for NiA than for NiX. © 2018 Hydrogen Energy Publications LLC

Palladium ion-exchanged zeolite X (PdX) was prepared by zeolite impregnation with palladium acetylacetonate, followed by thermal degradation of the salt. PdX was characterised using SEM-EDS, ICP-OES and XRD. Analysis revealed presence of 7.78 wt.% of Pd in the form of PdO. Subsequently, PdX was tested for hydrogen evolution reaction (HER) in alkaline medium using linear scan voltammetry, chronoamperometry and electrochemical impedance spectroscopy measurements. The influence of addition of carbon black on the materials catalytic performance was also investigated. The HER kinetic parameters, including Tafel slope, exchange current density and activation energy, were determined. In order to provide atomic-level insights, experimental results were complemented by density functional theory calculations. It is suggested that favourable hydrogen adsorption energetics on PdO is responsible for efficient HER catalysis by this novel electrocatalyst. (c) 2017 Elsevier Ltd. All rights reserved.

This research describes a study of 11 selected samples of brick clays applied in roofing tile production, by using simultaneous thermal analysis. Additionally, the laboratory-sized samples were prepared and fired (850-950 °C) and technological properties were determined. Mathematical analysis was applied to sum all the experimental results and help discriminate the samples by their behavior during firing. The samples, very similar according to mineralogical and chemical content, as well as granulometry tests, were successfully grouped using principal component analysis (PCA). The PCA was used to explore and easily visualize the differences between samples. The PCA performed for differential thermal analysis (DTA), differential scanning calorimetry (DSC) and differential thermogravimetry (DTG) curves clearly showed that the heat flow was mainly influenced by carbonate content and its grain size, while DTG discriminated samples according to the contents of clay minerals and carbonates. In addition, dilatometry analysis revealed which samples underwent the highest densification during the firing process. The PCA analysis of fired products properties showed that the highest correlations were between water absorption with firing shrinkage and compressive strength.