Wyniki wyszukiwania - BazTech

1

Microstructural Analysis of Ambient Cured Phosphate Based-Geopolymers with Coal-Ash as Precursor

Burduhos Nergis Dumitru Doru, Vizureanu Petrica, Lupescu Stefan, Burduhos Nergis Diana Petronela, Perju Manuela-Cristina, Sandu Andrei Victor

Archives of Metallurgy and Materials

|

2022

|

Vol. 67, iss. 2

595--600

EN

An alternative for Ordinary Portland cement (OPC) consumption is the production and integration of green cement. In other words, the clinker consumption has to be replaced with new low-carbon binders. A possible solution was introduced by the geopolymerisation technology. However, the alkaline activation of geopolymers offers the possibility of obtaining greener materials with high properties, superior to OPC, but due to the high price of sodium silicate, their industrial use is limited. In the past few years, a new activator has been discovered, namely phosphoric acid. This study approaches the obtaining of coal ash-based geopolymers activated with acid solution cured at room temperature. Accordingly, phosphoric acid, 85% by mass, was diluted in distilled water to obtain a corresponding activation solution for H3PO4/Al2O3 ratio of 1.0 and two types of geopolymers were ambient cured (22°C ±2°C). Moreover, to evaluate the geopolymerisation potential of this system (coal ash - phosphoric acid), SEM and EDS analysis was performed to investigate their morphologic characteristics.

2

Wpływ modyfikacji bentonitu na jego właściwości adsorpcyjne

Kwaśny Justyna, Balcerzak Wojciech, Kryłów Małgorzata, Wassilkowska Anna, Ruggiero-Mikołajczyk Małgorzata

Przemysł Chemiczny

|

2020

|

T. 99, nr 9

1335--1338

PL

Przeprowadzono kwaśną aktywację bentonitu za pomocą kwasu solnego, uzyskując wzrost powierzchni właściwej BET adsorbentu o 228 p.p. Zmianie uległy również inne parametry powierzchniowe, takie jak średnica i objętość porów, a także powierzchnia i objętość mikroporów. Impregnacja bentonitu nanometrycznym tlenkiem cyrkonu(IV) nie przyniosła zamierzonych efektów i przyczyniła się do pogorszenia właściwości adsorpcyjnych bentonitu. Efektywność adsorpcji określano, przeprowadzając testy adsorpcji siarkowodoru w warunkach beztlenowych. Skuteczność impregnacji bentonitu oceniano na podstawie obrazów powierzchni adsorbentów, wykonanych za pomocą skaningowego mikroskopu elektronowego (SEM).

EN

Com. bentonite was activated with HCl soln. to increase its sp. surface area by 228 percentage points (p.p.). Changes of diam., pore volume, as well as area and volume of micropores were also obsd. The impregnation of bentonite with nanometric ZrO₂ resulted in deterioration of the adsorption capacity of bentonite. The bentonite adsorbents were used for removal of H₂S from biogas under anaerobic conditions. The ZrO₂ modified bentonite was less efficient than the HCl-activated one, where 99% removal H₂S from N₂ stream was achieved.

3

Modified bentonite-derived materials as catalystsfor selective catalytic reduction of nitrogen oxides

Szymaszek Agnieszka, Kubeł Maciej, Samojeden Bogdan, Motak Monika

Chemical and Process Engineering

|

2020

|

Vol. 41, nr 1

13–-24

EN

In the last few years, cationic layered clays, including bentonites have been investigated as potentialcatalysts for SCR DeNOxsystems. In this work, bentonite as the representative of layered clays wasmodified in order to obtain an alternative, low-cost NH3–SCR catalyst. Samples of raw clay wereactivated with HCl or HNO3, treated with C2H2O4and subsequently pillared with alumina by the ion-exchange. Afterwards, the modified materials were impregnated with iron and copper. The obtainedcatalysts were characterized by XRD and FT-IR. SCR catalytic tests carried out over analyzed samplesindicated the conversion of NO of approximately 90% for the most active sample. The type of acidused for modification and the type of active phase strongly influenced the catalytic properties of theanalyzed materials.

4

Preparation of activated bentonite and its adsorption behavior on oil-soluble green pigment

Zheng R., Gao H., Ren Z., Cen D., Chen Z.

Physicochemical Problems of Mineral Processing

|

2017

|

Vol. 53, iss. 2

829--845

EN

The present research work focuses on effective preparation of activated bentonite (AB) and its application in removal of oil-soluble green pigment (OSGP) from either vegetable oils or food-processing wastewater. Mono-factor experiments were carried out to explore the effects of operation factors in preparation of AB. The parameters investigated were the effect of contact time, adsorbent dosage, initial OSGP concentration and temperature. The chemical composition, crystalline phases, microstructure and functional groups of prepared AB were characterized and evaluated by X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR), respectively. The adsorption kinetics and equilibrium isotherms were studied, finding that the adsorption process fitted better with the pseudo-second-order model and the Freundlich isotherm equation. In addition, thermodynamic parameters, such as standard the Gibbs free energy (ΔG°), standard enthalpy (ΔH°) and standard entropy (ΔS°) were also calculated, indicating that adsorption was spontaneous and endothermic. The findings of this investigation suggest that AB prepared through microwave activation as a cheap adsorbent holds great potential to remove oil-soluble green pigment in the wastewater treatment process.

5

Removal of phenol from wastewater using activated waste tea leaves

Mohsin K., Anwar R. S., Nadeem F., Amir Y., Syed W. A.

Polish Journal of Chemical Technology

|

2013

|

Vol. 15, nr 2

1--6

EN

This investigation enumerates the treatment of phenol contaminated synthetic wastewater by Activated Waste Tea Leaves (AWTL). Phosphoric acid was used for the modification of waste tea leaves. The effects of initial pH, biosorbent dose, contact time, and initial phenol concentration were studied on the phenol uptake from the synthetic solution. Kinetic modelling was performed using pseudo 1st and 2nd order kinetics. The Langmuir and Freundlich’s Models were employed to interpret the AWTL behaviour at various mass transfer gradients. The results show that the optimum values for pH, biosorbent dose and contact time were 2.2 g/L and 180 minutes, respectively. Pseudo 2nd order kinetic and the Langmuir’s Models best described the kinetic and equilibrium behaviours, respectively.

6

Influence of acid activation on the ion-exchange properties of manisa-gordes clinoptilolite

Yorukoglu A.

Physicochemical Problems of Mineral Processing

|

2012

|

Vol. 48, iss. 2

591-598

EN

In this study, the possibilities of using Manisa-Gördes district tuffs having important deposits rich of clinoptilolites have been investigated for the removal of heavy metal ions from industrial wastewaters. Adsorption of ammonium and metal cations such as Pb++, Cu++, Cd++ and Zn++ ions from aqueous solution onto sulphuric, hydrochloric and nitric acid activated samples were studied. Experimental data were obtained from batch equilibrium tests on samples activated at different acid concentrations at two different size fractions. It has been found that selectivity of the zeolite is sequentially Pb++ > NH4 + > Cu++, Cd++ > Zn++. Experimental results show that the NH4 + ion exchange capacity of 95 meq/100 g for the raw material can be increased to 140 meq/100 g after activation with sulphuric acid. In general, acid activation was observed to increase the ion exchange capacity, sulphuric acid responding better than hydrochloric and nitric acids.

7

Sedimentological and technical studies on the montmorillonitic clays of abu tartur plateau, western desert, Egypt

Sediek K.N., Amer A. M.

Physicochemical Problems of Mineral Processing

|

2007

|

Vol. 41

89-99

EN

One of the most known sedimentary formation among Egyptian Upper Cretacous rock units is named Duwi Formation (Lower Maastrichtian), an outcrop at the Abu Tartur plateau, Kharga Oasis, Western Desert, Egypt. This formation displays three montmorillonitic clayey layers. The investigations of these sediments provide information on the texture, constituents and type of clay minerals, which helps define and describe their physical and technical properties. Granulometrically, the selected samples have siltstone, mudstone and claystone facies. Mineralogical analysis of the studied deposits proved that the clay minerals compose mainly of montmorillonite, in addition to small amount of glauconite, and traces of illite. Scanning electron microscopy revealed three main micro-structures, namely honeycomb, matrix, and turbulent. Acid activation of eight samples was performed using hydrochloric acid. The efficiency of activation was examined by measuring their bleaching capacity to crude cotton seed oil, and changes in their surface areas. The acid treatment resulted in more than 4-fold increase in the activity of the pretreated bentonite samples. The extent of activation was found to be pronounced after the first 30 minutes of acid treatment.

PL

Jednym z najbardziej znanych utworów osadowych skał Egipskiego Górnego Cretacous jest formacja Duwi w Dolnym Maastrichtianie wysadu Równiny Abu Tartur Oazy Charga na Egipskiej Pustyni Zachodniej. Formacja ta posiada trzy warstwy montmorylonitowe. Badania osadów dostarczyły informacji o teksturze, składnikach i typie minerałów gliniastych, co pomaga definiować i opisywać ich fizyczne oraz techniczne właściwości. Badane próbki zawierały facje pyłowe, mułowe i gliniaste. Analiza mineralogiczna badanych osadów wykazała że minerały gliniaste zawierały głównie montmorylonit, a także małe ilości glaukonitu i ślady illitu. Skaningowa mikroskopia elektronowa wykazała trzy główne mikro-struktury, a mianowicie plastra miodu, matrycową i chaotyczną. Przeprowadzono aktywację kwasową ośmiu próbek stosując kwas chlorowodorowy. Skuteczność aktywacji badano poprzez pomiar zdolności do wybielania surowego oleju z nasion bawełny oraz zmiany w ich obszarach powierzchniowych. Aktywacja kwasem prowadziła do czterokrotnego wzrostu aktywności próbek. Stopień aktywacji był znaczący po pierwszych 30 minut traktowania kwasem.