Multi-component sorption studies are essential to identify the applicability
of red mud as a low-cost sorbent for the simultaneous removal of metal ions
from wastewaters. Sorption kinetics of Co2+ and Sr2+ionswas studied, at
their different molar ratios in the mixture. The pseudo-second-order rate
model best described the kinetics of metal sorption from binary metal
systems. The increase of initial concentration of each cationin the mixture
provoked its increased sorption capacity, but decreased sorption rate.
Co2+sorption was superior in terms of both the rate and the capacity,
therefore exertedstrong inhibitory effect on Sr2+sorption

Milenković, Aleksandra S.

Smičiklas, Ivana D.

Vukelić, Nikola

Šljivić-Ivanović, Marija Z.

Repository of the Vinča Nuclear Institute (VinaR)

     PHYSICAL CHEMISTRY 2014  12th International Conference on Fundamental and Applied Aspects of Physical Chemistry          The Conference is dedicated to the 25. Anniversary of the Society of Physical Chemists of Serbia            September 22-26, 2014  Belgrade, Serbia   II   ISBN 978-86-82475-30-9 Title: PHYSICAL CHEMISTRY 2014 (Proceedings) Editors: Ž. Čupić and S. Anić Published by: Society of Physical Chemists of Serbia, Studenski trg 12-16, 11158, Belgrade, Serbia Publisher: Society of Physical Chemists of Serbia For Publisher: S. Anić, President of Society of Physical Chemists of Serbia Printed by: “Jovan” Priting and Publishing Company; 200 Copies; Number of pages: 6+ 441; Format: B5; Printing finished in September 2014.  Text an Layout: “Jovan”  Neither this book nor any part may be reproduced or transmitted in any form or by any means, including photocopying, or by any information storage and retrieval system, without permission in writing from the publisher.  200 - Coppy priting    IV  PHYSICAL CHEMISTRY 2014  12th International Conference on  Fundamental and Applied Aspects of Physical Chemistry     Organized by The Society of Physical Chemists of Serbia  in co-operation with   Institute of Catalysis Bulgarian Academy of Sciences   Boreskov Institute of Catalysis of Siberian Branch of the Russian Academy of Sciences  Faculty of Physical Chemistry, University of Belgrade, Serbia  Institute of Chemistry Technology and Metallurgy,  University of Belgrade, Serbia  Vinča Institute, University of Belgrade, Serbia  Institute of General and Physical Chemistry, Serbia    Faculty of Pharmacy, University of Belgrade, Serbia    VInternational Organizing Committee  Chairman:  S. Anić (Serbia) Vice-chairman:  M. Gabrovska (Bulgaria)                             V. A. Sadykov  (Russia)  Members: N. Cvjetičanin (Serbia), S. N. Blagojević (Serbia), M. Daković (Serbia), T. Grozdić (Serbia), D. Jovanović (Serbia), M. Kuzmanović (Serbia), D. Marković (Serbia), J. Marković-Dimitrić (Serbia), B. Milosavljević (USA), M. Mojović (Serbia), N. Ostrovski (Serbia), I. Pašti (Serbia), M. Petković (Serbia), A. Popović-Bjelić (Serbia),  B. Simonović (Serbia), D. Stanisavljev (Serbia),  B. Šljukić (Serbia), N. Vukelić (Serbia), V. Vukojević (Sweden)  International Scientific Committee  Chairman:  Ž. Čupić (Serbia) Vice-chairmans: V. N. Parmon (Russia)                                   S. Rakovsky (Bulgaria) Members: B. Adnađević (Serbia), S. Anić (Serbia), A. Antić-Jovanović (Serbia), G. Bačić (Serbia), A. Kelarakis (Greece), R. Cervellati (Italy), V. Dondur (Serbia), Ivan Gutman (Serbia), S. D. Furrow (USA), K. Hedrih (Serbia), M. Jeremić (Serbia), A. V. Knyazev (Russia), Lj. Kolar-Anić (Serbia), V. Kuntić (Serbia), Z. Marković (Serbia),  S. Mentus (Serbia), Š. Miljanić (Serbia), M. Perić (Serbia), M. Plavšić (Serbia), D. M. F. Santos (Portugal), G. Schmitz (Belgium), I. Schreiber (Czech), P. Sevčik (Slovakia), B. C. Simionescu (Romania), N. Stepanov (Russia), D. Todorović (Serbia), M. Trtica (Serbia), V. Vasić (Serbia), D. Veselinović (Serbia)   Local Executive Committee  Chairman:              S. Blagojević Vice-chairmans:    A. Ivanović-Šašić  Members: P. Banković,  N. Bošnjaković, J. Dostanić,  A. Đerić, A. Ignjatović, A. Jović, N. Jović-Jovičić, D. Lončarević, J. Krstić, J. Maksimović, V. Marković, M. Milenković, S. Maćešić, V. Marković, B. Nedić, N. Potkonjak, D. Ranković, M. Stević, M. Žunić, M. Ristić,          PHYSICAL CHEMISTRY 2014  C-19-P   292KINETIC STUDY OF COMPETITIVE Co2+ AND Sr2+SORPTION BY BAUXITE RESIDUE  A. Milenković1, I. Smičiklas1, M. Šljivić-Ivanović1 and N. Vukelić2  1 University of Belgrade, “Vinča” Institute of Nuclear Sciences, Radiation and Environmental Protection Department, P.O. Box 522, 11000 Belgrade, Serbia(aleksmileks@gmail.com) 2University of Belgrade, Faculty of Physical Chemistry, Studentskitrg 12-16, P. O. Box 137, 11001 Belgrade, Serbia  ABSTRACT Multi-component sorption studies are essential to identify the applicability of red mud as a low-cost sorbent for the simultaneous removal of metal ions from wastewaters. Sorption kinetics of Co2+ and Sr2+ionswas studied, at their different molar ratios in the mixture. The pseudo-second-order rate model best described the kinetics of metal sorption from binary metal systems. The increase of initial concentration of each cationin the mixture provoked its increased sorption capacity, but decreased sorption rate. Co2+sorption was superior in terms of both the rate and the capacity, therefore exertedstrong inhibitory effect on Sr2+sorption.  INTRODUCTION Due to high efficacy and low-cost, sorption processes can be applied for the decontamination of liquid radioactive wastes [1]. Nowadays, wastes and by-productsfrom various industries are studied as potential sorbents [2]. Red mud, an alkaline by-product of alumina industrial production from bauxite ore, is an example of heterogeneous mineral material interesting for environmental applications [3]. In the previous study, alkaline red mud from “Birač” Alumina Factory (Bosnia and Herzegovina) was found to be a promising sorbent for 60Co and 90Sr ions [4]. Thesetwo radioactive isotopes go hand in hand as products of nuclear reactor operations: 60Co isa corrosion product, while 90Sr occurs by fission of uranium and plutonium. Therefore, multi-component sorption studies are required to identify the capabilities and limitations of red mud as a low-cost sorbent for the simultaneous removal of these metal ions from wastewater.  In this paper, time dependant sorption of 60Co and 90Sr was examined using mixtures with different molar ratios of selectedcations.         PHYSICAL CHEMISTRY 2014  C-19-P   293EXPERIMENTAL After settling, the liquid phase above red mud particles was decanted,whereas the solid residue was dried at 105oC and homogenized in the mortar. Stock solutions of Co2+ and Sr2+ions (2.10-3 mol/dm3) were prepared by dissolving Co(NO3)2·6H2O and Sr(NO3)2salts, in deionized water. Simulated liquid wastes with different molar ratios of two cations(Co2+: Sr2+ = 1:2, 1:1 and 2:1) were prepared from stock solutions, keeping the overall cation concentration constant (2.10-3 mol/ dm3). The initial pH of each mixture was adjusted to 5, with a few drops of 0.01 mol/dm3 HNO3. The effect of contact time on the amount of cations removed was determined by equilibrating 0.1000 g of red mud with 20.00 cm3 of mixture solutions, on the laboratory shaker.At different time intervals ranging from 15 min to 48 h, one of the batches was taken for solid/liquid separation. Sorbedcation concentrations were determined by Perkin Elmer 3100 Atomic Absorption Spectrometer, as differences between initial and final concentrations.   RESULTS AND DISCUSSION The amounts of Co2+ and Sr2+sorbedat various time intervals from the mixed solutions are presented in the Fig. 1. It can be observed that thesorption onto red mud wasgenerally fast during first hours of contact, followed by a slower reaction step.With the increase of initial concentration of each cation,equilibration time increased as well. Equilibrium times for Co2+ sorption were 6 h for 1:2 molar ratio to Sr2+, and 24 h for the ratios 1:1 and 1:2. Sorption of Sr2+ reached equilibrium in 6 h and 30 h, for Co2+: Sr2+ molar ratios 2:1 and 1:1, respectively, whereas for the ratio 1:2 sorbed amounts of Sr2+ slightly increased during the second day of equilibration.  Applicability of several kinetic models for the interpretation of experimental results was tested. Highest correlation coefficients (R2) between the model and the experimental results were obtained using the pseudo-second-order kinetic equation [5]:       (1)    where k2 (g/(mmol min)) is the pseudo-second-order rate constant, qe (mmol/g) the amount of cationsorbed at equilibrium, and qt is the amount of cationsorbed at any time t. Calculated kinetic parameters are presented in Table 1. Calculated sorption capacities increased along with the initial concentration of a particular cation, whereas the rate constants decreased.  From binary solutions,Co2+ was sorbed more selectively on red mud surface, showing higher qe and k2 values. Consideringequimolar mixture, Co2+ sorption capacity was almosttwice theamount of Sr2+sorbed (0.203 mmol/g        PHYSICAL CHEMISTRY 2014  C-19-P   294and 0.117 mmol/g, respectively). The equilibrium sorbed amounts from single metal solutions (initial cationconcentration 10-3mol/dm3) were found to be 0.206 mmol/g for Co2+ and 0.197 mmol/gSr2+[4].  0 500 1000 1500 2000 2500 30000,000,050,100,150,200,25Co2+  sorbed amount (mmol/g)t  (m in)M ola r ra tioC o 2+:S r2+ 1 :1 2 :1 1 :2A ) 0 5 0 0 1 0 0 0 1 5 0 0 2 0 0 0 2 5 0 0 3 0 0 00 ,0 00 ,0 50 ,1 00 ,1 50 ,2 0 M o la r  ra t ioC o 2 + :S r 2 + 1 :1 2 :1 1 :2Sr2+ sorbed amount (mmol/g)t  (m in )B ) Figure 1. Effect of contact time on competitive Co2+ (A) and Sr2+ (B)sorption by red mud.  Table 1.The parameters of pseudo-second-order kinetic model  for competitive Co+2 and Sr2+ sorption onto red mud Molar ratio Co:Sr Co2+ Sr2+ qe mmol/g k2 g/(mmolmin) R2 qe mmol/gk2 g/(mmolmin) R2 1:2 0.134 0.412 0.99 0.205 0.015 0.98 1:1 0.203 0.128 0.99 0.117 0.033 0.98 2:1 0.275 0.043 0.99 0.045 0.227 0.99  Foreach binary system, total sorption capacity remainedrelatively constant (Σqe = 0.326±0.006 mmol/g).Individual and overall sorbed amounts are        PHYSICAL CHEMISTRY 2014  C-19-P   295presented in Fig. 2. The results demonstrate that the presence of Sr2+ ions in the mixture did not interfere with Co2+ sorption. Conversely, Co2+ inhibited removal of Sr2+.  CONCLUSION With the increase of the initial concentration of a particular cation in the mixture,its sorption capacity increased, whereasthe corresponding pseudo-second-order rate constant decreased. Considering experimental conditions applied in this study, red mud can be utilized for simultaneous removal of Co2+ and Sr2+cations. However, coexisting Sr2+ions did not affect Co2+ sorption capacity, while Co2+exerted strong inhibitory effect on Sr2+ removal.   ACKNOWLEDGEMENT  This work was supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia (Project III43009).  REFERENCES [1] IAEA-TECDOC-1336, Combined methods for liquid radioactive waste treatment, Final report of a coordinated research project, 1997–2001, Vienna 2003. [2] S. Bailey,T. R. Olin, M. A. Dean, A review of potentially low-cost sorbents for heavy metals, Water Res.,1999, 33, 2469–2479. [3] S. Wang, H. M. Ang, M. O. Tadé, Novel applications of red mud as coagulant, adsorbent and catalyst for environmentally benign processes, Chemosphere 2008, 72, 1621–1635. [4] A.Milenković, I.Smičiklas, J.Marković, N.Vukelić, Immobilization of 60Co and 90Sr ions using red mud from aluminum industry, Nuclear Technology & Radiation Protection, 2014, 29, 79-87. [5] Y.S. Ho, G. McKay, Pseudo-second order model for sorption processes, Process Biochem., 1999, 34, 451–465. 0,000,050,100,150,200,250,300,35(100%)(100%)1Co:2Sr1Co:1Sr2Co:1SrEquilibrium sorption  (mmol/g)Molar ratio of cations  Co2+    Sr2+(100%)(71.0%)(33,5%)(55,7%)Figure 2.  Individual and overall amounts of Co2+andSr2+sorbed  by red mud  from binary mixtures.  

Kinetic study of competitive CO2+ and Sr2+sorption by bauxite residue

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Kinetic study of competitive CO2+ and Sr2+sorption by bauxite residue

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