Temat: pumice - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Response surface methodology (RSM) and its application for optimization of ammonium ions removal from aqueous solutions by pumice as a natural and low cost adsorbent
Autorzy:: Moradi, M.
Fazlzadehdavil, M.
Pirsaheb, M.
Mansouri, Y.
Khosravi, T.
Sharafi, K.
Tematy:: pumice
ion adsorption
response surface methodology; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/950773.pdf Link otwiera się w nowym oknie
Opis:: This research was conducted to study the adsorption of ammonium ions onto pumice as a natural and low-cost adsorbent. The physico-chemical properties of the pumice granular were characterized by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Modeling and optimization of a NH₄+ sorption process was accomplished by varying four independent parameters (pumice dosage, initial ammonium ion concentration, mixing rate and contact time) using a central composite design (CCD) under response surface methodology (RSM). The optimum conditions for maximum removal of NH₄+ (70.3%) were found to be 100 g, 20 mg/l, 300 rpm and 180 min, for pumice dosage, initial NH₄+ ion concentration, mixing rate and contact time. It was found that the NH₄+ adsorption on the pumice granular was dependent on adsorbent dosage and initial ammonium ion concentration. NH₄+ was increased due to decrease the initial concentration of NH₄ and increase the contact time, mixing rate and amount of adsorbent.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Lightweight Geopolymer Made of Pumice with Various Aluminum Powder Ratios
Autorzy:: Çetınkaya, S.
Kurt, H.
Kütük, N.
Tematy:: lightweight geopolymers
pumice
compressive strength
aluminum powder; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1031665.pdf Link otwiera się w nowym oknie
Opis:: In this work, a lightweight geopolymer was prepared using various mass proportions of extra fine aluminum powder and pumice stone that is durable to heat and sound-proof. The effect of NaOH concentration, aluminum mass ratio, the curing temperature and the curing time of the mixture on the compressive strength of the lightweight geopolymers were examined. The concentration of NaOH was found to be 2 M while the mass proportion of Na₂SiO₃/NaOH was found to be 17.5 on the lightweight geopolymers that have the highest compressive strength and the best workability in experiments. The lightweight geopolymer attained the best compressive strength with 1.6 MPa on the 28th day of curing process at 40°C. The mass proportion of aluminum used in the lightweight geopolymer was 2.5% as the density of the lightweight geopolymer obtained was 0.9 g/cm³. Their properties were examined using the Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Use of pumice and scoria aggregates for controlling alkali silica reaction
Autorzy:: Tapan, M.
Tematy:: alkali-silica reaction
aggregate
pumice
scoria
SEM; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/110861.pdf Link otwiera się w nowym oknie
Opis:: Turkey has important potential pumices reserves (68% of the reserve of the world) and 56 % of pumice reserve of Turkey is in the East Anatolia Region. It is important to assess huge pumice reserves in Eastern Turkey for its use in the cement and concrete industry. Use of acidic pumice and basic pumice (scoria) as cement additive or aggregate are gaining popularity because of their proven structural/durability properties. This paper presents the results of an investigation to assess the effectiveness of pumice and scoria aggregates in controlling alkali silica reaction (ASR) of alkali silica reactive aggregate using the following test methods: the accelerated mortar bar test (ASTM C 1260) and the scanning electron microscopy technique (SEM). The morphologies, structures and properties of the samples were determined by XRD, ICP-MS, XRF and thin section study. Mortar cubes were specially prepared according to ASTM standards using 10, 20 and 30% pumice or scoria aggregate as alkali silica reactive aggregate replacement. The results are compared with ASTM requirements to assess the suitability of pumice or scoria for preventing alkali silica reactivity. According to the results of these methods, pumice aggregates control the alkali silica reaction whereas scoria aggregates decrease expansion but is not as effective as pumice in preventing ASR. The results of SEM analysis showed alkali silica gel formation and serious decomposition of aggregate texture due to ASR in scoria added mortar bars.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Elimination of Hexavalent Chromium Ions in Water Using a Manganese-Coated Pumice Adsorbent
Autorzy:: Lestari, Puji
Purwiandono, Gani
Pramayshela, Shike
Siswoyo, Eko
Tematy:: adsorption
hexavalent chromium
isotherm
Mn-coated pumice; Pokaż więcej
Wydawca:: Polskie Towarzystwo Inżynierii Ekologicznej
Powiązania:: https://bibliotekanauki.pl/articles/59114164.pdf Link otwiera się w nowym oknie
Opis:: A natural pumice stone stone coated with manganese (Mn) has been prepared and utilized to remove hexavalent chromium (Cr(VI)) ions in water via adsorption process. Prior to the application, the natural pumice was ground, sieved, and immerse in a dilute HCl solution. The coating of Mn on the acid-activated pumice was carried out by soaking the powder in 0.5 M Mn(NO3)2 solution for 72 h. The characterisation of the produced pumice adsorbent was performed with scanning electron microscopy and fourier-transform infrared spectroscopy instruments. The adsorption of Cr(VI) onto Mn-coated pumices was optimum at pH 3. Both the Langmuir and Freundlich isotherm models could be used to describe the adsorption process. The rate of adsorption followed the model for pseudo- second-order kinetics. The maximum adsorption capacity of Mn-coated pumice towards Cr(VI) ions was 1.94 mg/g.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Effect of Pumice Powder on Mechanical, Thermal, and Water Absorption Properties of Fiberboard Composites
Autorzy:: Şeker, Ulvi
Koyuncu, Menderes
Ulay, Göksel
Wydawca:: Sciendo
Cytata wydawnicza:: Koyuncu M, Ulay G, Şeker U. Effect of Pumice Powder on Mechanical, Thermal, and Water Absorption Properties of Fiberboard Composites. Fibres & Textiles in Eastern Europe. Sciendo, 2023;31}(3): 30-36. https://doi.org/10.2478/ftee-2023-0025
Opis:: Composites were produced using medium-density fiberboard (MDF) flour with pumice powder which was mixed at various ratios by the hand lay-up technique. Mechanical properties, such as tensile and three-point bending strengths, were determined by ASTM D3039 and ASTM D790 respectively. The best three-point bending and tensile strength properties were maximum values obtained from composites containing 20wt% pumice powder (pp) and 50wt% pumice powder (pp) respectively. It is observed that the water absorption rate into the composites decreases with an increase in the pumice powder-to-ratio. The composite filled with 50wt%pumice powder absorbed the least amount of water compared to the other composites. All composites were characterized by scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FTIR), and differential scanning calorimetry analysis (DSC). SEM images revealed a near-homogeneous surface partly free of defects and holes. However, lateral profile images showed the presence of MDF flour particles agglomerated and a considerable number of bubbles and cavities that could interfere with the mechanical properties of the composites. The results of the mechanical, and thermal properties suggested that pumice powder epoxy composites with MDF flour can increase their tensile, three-point-bending strength, and glass transition temperature for the pure MDF flour composite.
Dostawca treści:: Repozytorium Centrum Otwartej Nauki

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Skocz do pozycji: 6.

Tytuł:: Immobilization of Lycinibacillus fusiformis B26 cells in different matrices for use in turquoise blue HFG decolourization
Autorzy:: Dogan, N. M.
Sensoy, T.
Doganli, G. A.
Bozbeyoglu, N. N.
Arar, D.
Akdogan, H. A.
Canpolat, M.
Tematy:: agar
calcium alginate
decolourization
FTIR
immobilization
pumice; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/204696.pdf Link otwiera się w nowym oknie
Opis:: The decolourization of Turquoise Blue HFG by immobilized cells of Lysinibacillus fusiformis B26 was investigated. Cells of L. fusiformis B26 were immobilized by entrapment in agar and calcium alginate matrices and attached in pumice particles. The effects of operational conditions (e.g., agar concentrations, cell concentrations, temperature, and inoculum amount) on microbial decolourization by immobilized cells were investigated. The results revealed that alginate was proven to be the best as exhibiting maximum decolourization (69.62%), followed by agar (55.55%) at 40°C. Pumice particles were the poorest. Optimum conditions for agar matrix were found: concentration was 3%, cell amount was 0.5 g and temperature was 40°C (55.55%). Ca-alginate beads were loaded with 0.5, 1.0 and 2.0 g of wet cell pellets and the highest colour removal activity was observed with 2.0 g of cell pellet at 40°C for alginate beads. Also, 0.5 and 1.0 g of pumice particles that were loaded with 0.25 and 0.5 g of cell pellets respectively were used and the results were found very similar to each other.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Suitability and characterization of pumice, bauxite, and ferrochrome slag as alternative raw materials in vitrified ceramic industry
Autorzy:: Benkli, Yunus Emre
Koca, Kazım
Tematy:: vitrified ceramics
pumice
ferrochrome slag
bauxite
industrial waste; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/58971236.pdf Link otwiera się w nowym oknie
Opis:: Since the natural raw materials used in the manufacture of clay-based ceramic products vary greatly in the sintering stage, the resulting products are quite heterogeneous. In addition, different types of waste could be used to make ceramic tiles and bricks. Therefore, this study aimed to investigate the effects of pumice, bauxite, and ferrochrome slag on the vitrified ceramic body. In this context, firstly, binary slip mixtures were prepared by composing 40% clay with 60% pumice, bauxite, and ferrochrome slag one by one, which was reduced to 150 μm in particle size. Then, the mixtures were shaped by slip casting method and sintered at 1000°C, 1100°C, 1200°C, and 1250°C. The qualitative XRD analysis was performed in order to see the phase variation, and physical properties were determined with shrinkage and water adsorption measurements. Since pumice transformed into a glassy phase after sintering at 1100°C, an amorphous phase was observed in all samples produced with pumice. In addition, the mullite development occurred in clay-pumice body composition with the temperature increment. However, tridymite and cristobalite phases were analysed in clay bauxite and ferrochrome body compositions. The shrinkage and water adsorption values, which were high in the samples sintered at 1000°C, began to reduce from 1100°C to 1250°C significantly. In particular, water adsorption reached 0% in the clay-pumice system which was suitable for a fully vitrified-high density standard (ISO13006-10545/98). Besides, the brighter colour was reached in the clay-pumice system while brown and black colour was seen in clay-bauxite and clay-ferrochrome bodies, respectively.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Evaluation of Mechanical Properties of Lightweight Concrete with Pumice Aggregate
Autorzy:: Shafiq, Malik Salman
Khan, Fasih Ahmed
Badrashi, Yasir Irfan
Khan, Fayaz Ahmed
Fahim, Muhammad
Abbas, Asim
Adil, Waqas
Tematy:: lightweight concrete
pumice lightweight aggregate
saline water curing; Pokaż więcej
Wydawca:: Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Powiązania:: https://bibliotekanauki.pl/articles/2024034.pdf Link otwiera się w nowym oknie
Opis:: This paper presents the findings of a study carried out for evaluation of the mechanical behavior of lightweight concrete. Pumice, a rock resulting from cooling of lava, having entrapped air bubbles, has been used as a light- weight coarse aggregate. Evaluation of the mechanical behavior of the Pumice Lightweight Aggregate Concrete (PLWAC) has been carried out in comparison with the conventional concrete while comparing the mechanical properties of the two. Complete replacement of the coarse aggregate by volume had been carried out in the PLWAC. The testing regime consisted of conducting laboratory tests on concrete samples for evaluation of the mechanical properties including compressive strength, tensile stength, workability and dry density. It was concluded from the results that the use of lightweight aggregate resulted in a reduction in workability, as indicated by the slump test. Moreover, the dry density of PLWAC was also reduced by 30% as compared to the conventional concrete. A significant decrease (49%) in the compressive strength of PLWAC as compared to conventional concrete while a minor difference was observed in the tensile strenght of the two (2.9%). Based on the results of this study, it is recommended that PLWAC cannot be used in structures subjected to heavy loading conditions. However, PLWAC has a good potential to be used in low-cost structures with accompanying benefits of weight reduction.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Analiza możliwości wielokrotnego zastosowania matrycy wykonanej z pumeksu do kowalencyjnego wiązania inwertazy EC 3.2.1.26
Analysis of possibility of reutilization of pumice stone matrix for covalent binding of invertase EC 3.2.1.26
Autorzy:: Raducka, A.
Ogoński, T.
Tematy:: inwertaza
immobilizacja
pumeks
regeneracja
invertase
immobilization
pumice stone
regeneration; Pokaż więcej
Wydawca:: Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Powiązania:: https://bibliotekanauki.pl/articles/2070483.pdf Link otwiera się w nowym oknie
Opis:: Jednym z czynników decydujących o przydatności materiału do zastosowania jako matrycy w przemysłowych procesach z użyciem immobiIzowanych enzymów jest możliwość jego wielokrotnego użycia. W pracy cy przedstawiono wyniki doświadczalnych badań przydatności pumeksu meksu do wielokrotnego wiązania inwertazy. Stwierdzono, że granulowany pumeks jest nośnikiem, który można regenerować i wielokrotnie stosować do wiązania inwertazy z Saccharomyces cerevisiae.
One of the most important factors deciding which material is a suitable support for covalent binding of enzymes is the ability of that material to reutilization. In this work the matrix made from granulated pumice stone was used for baker's yeast invertase covalent immobilization. It was found that granulated pumice stone might be regenerate( and reused for invertase immobilization.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Obtaining lightweight concrete using colemanite waste and acidic pumice
Autorzy:: Erdogan, Y.
Yasari, E.
Gamage Ranjith, P.
Tematy:: lightweight concrete
colemanite waste
acidic pumice
density
uniaxial compressive strength; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/109990.pdf Link otwiera się w nowym oknie
Opis:: This paper presents some results of ongoing laboratory work to design a lightweight concrete using colemanite waste and pumice. Hisarcik and Espey colemanite wastes, acidic pumice aggregate as well as normal Portland cement were used to produce lightweight concrete with economic and environmental advantages. Two different groups and twenty different prescriptions were tried to produce lightweight concrete. The effect of colemanite waste on workability and strength of lightweight concrete were analysed by fresh and hardened concrete tests. The properties of materials examined include slump, air content, density and uniaxial compressive strength of the mortar. The results obtained were compared with control concrete properties and Turkish standard values. The examined tests results showed that lightweight concrete can be produced by the use of acidic pumice aggregate and colemanite waste. Furthermore, the colemanite waste can be used as cement additives and can reduce the cost and environmental pollution with using natural stone aggregate.
Dostawca treści:: Biblioteka Nauki

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