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Potential of pumice modified with iron(III) for copper removal from aqueous solutions

Guler U. A., Cebeci M. S.

Environment Protection Engineering

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2017

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Vol. 43, nr 3

165--180

EN

Iron-modified pumice (Fe-P) was prepared by the ion-exchange method using natural pumice from Kayseri, Turkey at room temperature without calcination. SEM, FTIR, XRD, and S-BET measurement were used to investigate the copper removal mechanism. The results show that the SBET of the pumice increased from 11.88 m2/g to 21.01 m2/g after iron modification. The effects of pH, contact time, initial copper concentration, temperature, and various cations (Na+, K+, Ca2+, Mg2+ and Al3+) at various pH were investigated in batch experiments. More than 92% of Cu(II) was removed after 180 min. Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherm models were applied to the equilibrium data at 298, 308 and 318 K. The maximum adsorption capacity at 298, 308 and 318 K was found to be 21.52, 19.48, and 19.67 mg/g, respectively. The kinetics of copper on Fe-P was best described by the pseudo-second order kinetic model. The negative values of free energy change and enthalpy change indicated that the adsorption process was feasible, spontaneous and exothermic.

2

Casting structure change caused by magnetic field

Szajnar J.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 24, nr 1

297-306

EN

Purpose: In this work problems of crystallization process for pure metal and alloy castings solidifying under forced convection resulting from use of rotational or rotational reversing magnetic field are presented. Design/methodology/approach: Influence of changes caused by forced convection in solidification conditions on columnar crystals zone and its limitation was studied. Obtained results show that magnetic field changes thermal and concentration conditions. Both conditions are connected with magnetic field induction B, that is with liquid metal velocity Vcm ahead of crystallization front. Examples of magnetic field application for casting structure change are shown. Findings: Model of columnar to equiaxed structure transition was based on modified concentration stability criterion of crystallization front, in which measurements of alloy addition concentration along ingot radius were incorporated. Gradient-kinetic conditions were evaluated with use of computer simulation of solidification process. Crystallization conditions at the interface enabled tracking of solidification process for actual casting from its surface to its axis. It was then possible to analyze relation between thermal and concentration conditions in time of solidification and to determine position of crystallization front stability loss, which after some simplifications can be considered as the columnar crystals zone width. Research limitations/implications: Experimental results confirmed justness of introduced model. In analysis also simulation results were used describing liquid metal flow ahead of crystallization front for different types of the interface showing qualitative relations between crystallization front geometry and structure changes. Practical implications: Relations are proposed, which can be used for columnar crystals zone width taking into account nominal concentration of alloy addition Co, forced by magnetic field liquid metal velocity Vcm and thermal conditions represented by pouring temperature Tzal, thermal gradient at the crystallization front at the moment of forced convection termination GT or difference in temperature on casting cross section delta T. Originality/value: This paper is a result of several studies conducted in Foundry Department since many years and connected of physical factors (ultrasonic vibrations, electromagnetic field) influence on crystallization process of static and continuous castings.

3

Zmiany w rozkładzie miedzi jako przyczyna przemiany struktury w odlewach wykonywanych w polu magnetycznym

Szajnar J.

Archiwum Odlewnictwa

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2002

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R. 2, nr 4

454--459

PL

W pracy określono zmiany w rozkładzie stężenia miedzi w odlewach z Al-Cu krystalizujących pod wpływem wymuszonej konwekcji wirującym polem magnetycznym (WPM). Stwierdzono, że zmiany w rozkładzie miedzi wywołane wymuszonym ruchem ciekłej fazy są powodem przemiany struktury kolumnowej w równoosiową. Stwierdzono również, że ruch ciekłego metalu przed frontem krystalizacji jest przyczyną różnicowania się stężenia miedzi w kryształach kolumnowych.

EN

This work describes copper distribution changes in AlCu castings stirred by rotating magnetic field. It is claimed, that the changes in Cu distribution caused by forced movement of the liquid phase are the main reason of columnar to equiaxed transformation (CET). Movement of the liquid metal in front of CET interface is also a reason for different Cu content in columnar crystals.

4

Rozkład miedzi w kryształach kolumnowych w odlewach wykonywanych w polu magnetycznym

Szajnar J.

Archiwum Odlewnictwa

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2002

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R. 2, nr 6

213-218

PL

Działanie pola magnetycznego wywołuje zmiany w warunkach oddawania ciepła przez odlew i w rozkładzie składników stopowych. W pracy określono zmiany w rozkładzie stężenia miedzi w strefie kryształów kolumnowych w odlewach z AI-Cu krystalizujących pod wpływem wymuszonej konwekcji wirującym polem magnetycznym (WPM). Stwierdzono, że zmiany w rozkładzie miedzi wywołane wymuszonym ruchem ciekłej fazy są powodem przemiany struktury kolumnowej w równoosiową oraz zmiany kierunku wzrostu tych kryształów.

EN

This work describes copper distribution changes in AICu castings stirred by rotating magnetic field. It is claimed, that the changes in Cu distribution caused by forced movement of the liquid phase are the main reason of columnar to equiaxed transformation (CET). Movement of the liquid metal in front of CET interface is also a reason for different Cu content in columnar crystals.