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Effect of calcinated halloysite on structure and properties of rigid poly(vinyl chloride) composites

Wieczorek Martina, Tomaszewska Jolanta, Bajda Tomasz, Długosz Jacek

Chemical and Process Engineering

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2022

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Vol. 43, nr 3

383-–404

EN

Halloysite is a filler which may be used to produce composites with thermoplastic polymer matrix. This work summarized the results of investigations of processing, structural, mechanical, and thermal properties of the composites with poly(vinyl chloride) (PVC) matrix and raw halloysite (HA) as well as its calcined product (KHA). The effectiveness of calcination was confirmed with X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, and nitrogen adsorption method. The PVC composites with HA as well as KHA were processed in the molten state in the Brabender mixer chamber. The reduction of gelation time and simultaneous increase in maximum torque with filler content were found based on the results of plastographometric analysis. SEM images of PVC/halloysite composites showed a homogeneous distribution of the filler in the polymer matrix. The introduction of halloysite leads to a slight increase in Young’s modulus and tensile strength compared to neat PVC, where the increase of both parameters is greater when KHA is used. The incorporation of 1% KHA led to an increase in impact strength, an effect which may be attributed to toughening of the polymer. A slight improvement of the Vicat softening temperature of 2.7 degrees C for PVC/HA and heat deflection temperature of 2.4 C for PVC/KHA was also ascertained for PVC modified with 10 wt% of filler.

2

Time constraints on experimental studies of lead apatites

Topolska Justyna, Bajda Tomasz, Puzio Bartosz, Manecki Maciej, Kozub-Budzyń Gabriela

Geological Quarterly

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2019

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Vol. 63, No. 4

721--728

EN

The paper presents the results of experimental studies on the synthesis and thermodynamic stability of selected Pb-apatites in terms of criteria determining termination of the experiments. Based on the case study, we indicate difficulties in analysing the obtained experimental data. Time-resolved sampling of precipitate formed during a dropwise synthesis of pyromorphite was performed and the results were compared to the literature data. It has been concluded that the Ostwald ripening time for synthesized solids depends primarily on the chemical composition of the intended Pb-apatite phase. We presented that heterogeneity of precipitate affects its dissolution in terms of repeatability of the results and equilibrating time. A unique 9-year-long experiment on vanadinite stability at a pH range from 2.0-6.0 revealed that among all tested dissolution conditions only the reactions at the pH = 3.5 can perform as the basis for some thermodynamic calculations. It has been concluded that the rate of phase transitions in the Pb-apatites group can be misleading in terms of determining the equilibrium of the system, and the experimental setup designed particularly to provide reliable controls in this aspect should be involved. Means in this respect have been proposed.

3

Sorption of chromate by clinoptilolite modified with alkylammonium surfactants

Bajda Tomasz, Kłapyta Zenon

Mineralogia

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2006

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Vol. 37, iss. 2

93--98

EN

Clinoptilolite from Dylągówka (Poland) with an external cation exchange capacity (ECEC) of 16 meq/100 g determined by adsorption of alkylammonium ions was treated with hexadecyltrimethylammonium (C16) and dioctadecyldimethylammonium (2C18) bromides in amounts equivalent to 1.0 and 1.5 ECEC. The products were characterized using IR spectroscopy and C and N determinations. The sorption of chromate on the modified mineral was measured spectrophotometrically as a function of pH, concentration of Cr(VI) or the proportion of the sorbent to solution. The amount of chromate removed from the solution continuously decreased with increasing pH in the range 1.3-10. At pH 2.6-3.1, the maximum adsorption of Cr(VI) by the organo-zeolites (103 and 124 mmol/kg) was observed for the samples modified using a 1.5 ECEC surfactant concentration. Considerably lower adsorption values (37 and 46 mmol/kg) were obtained with sorbents prepared using a 1.0 ECEC concentration of the alkylammonium ions.

PL

Klinoptilolit z Dylągówki o zewnętrznej pojemności wymiany kationów (ECEC) 16 meq/100 g poddano modyfikacji przy użyciu bromków heksadecylotrimetyloamoniowego (C16) i dioktadecylodimetyloamoniowego (2C18) w ilości 1,0 i 1,5 ECEC minerału. Dla produktów reakcji wykonano badania spektroskopowe w podczerwieni oraz oznaczenia C i N. Sorpcję chromianów na otrzymanych organo-zeolitach określono spektrofotometrycznie jako funkcję pH, stężenia Cr(VI) lub proporcji sorbent/roztwór. Ze wzrostem pH w przedziale 1,3–10, ilości chromianów pochłanianych z roztworu systematycznie malała. Dla próbki modyfikowanej przy użyciu soli C16 w ilości 1,0 ECEC, graniczne wartości wynosiły 67 i 6 mmol/kg. Przy pH 2,6–3,1, maksymalną sorpcję Cr(VI) (124 i 103 mmol/kg) stwierdzono dla organo-zeolitów otrzymanych przy zastosowaniu 1.5 ECEC związków C16 i 2C18. Znacznie mniejsze wartości (46 i 37 mmol/kg) obserwowano w przypadku sorbentów zawierających jony alkiloamoniowe w ilości 1.0 ECEC. Ilość Cr(VI) usuniętego z roztworu przez organo-zeolity otrzymane dla stężenia wymienionych soli 1.0 ECEC nie zależała od wielkości jonów alkiloamoniowych związanych z powierzchnią zeolitu. Natomiast w przypadku stężenia 1.5 ECEC, próbka zawierająca kationy C16 wykazywała z reguły większą chłonność sorpcyjną względem tego pierwiastka w porównaniu z otrzymaną stosując kationy 2C18.