331 J. Saudi Chem. Soc., Vol. 9, No.2; pp. 331-340 (2005) CHELATION PROPERTIES OF SOME CONDENSATION POLYMERS TOWARD SOME TRIVALENT LANTHANIDE IONS Ayman A. Ahmad, Fuad AI-Rimawi, Fawwaz I. Khalili, and Mohammad S. Mubarak' Department of Chemistry, Faculty of Science, University of Jordan, Amman 11942, Jordan (Received 5 th June 2004; Accepted 12th Dec. 2004) J)"! ,I JG--2,6-.;.l.)\J,.I ..;:v- J)"! .,1') ,.....o.;I5:.:JI ,-""I.,J-I c.i ,yI5:.:JI .. ::.A.. vliy.i .Li. ,3 J)"!) ,2 cJ..... :..;.I) l.> :w..,..J-I :.:.,. ..:r)i <Jb i 'i rJ 'i 'i .r--' .. 'i j\:;;)'JI EDTA 0" C' vI-L........ Uli vlr-WI 0)...\..4.. -4..Li J.>- C10 4 - v,. :w. yi"" :.:.,. ...:...ilS" 0)';"; J.>-i l.>i ..be)) L.i...:;.lS" Xylenol orange JL.......:..-I ) l.>y.\) P'11..:r) Jt.:JI 0)';"; J.>-i yL:.lI A-U l.>i U)..l.ll Tb J + > Gd J + > Sm J + > Nd J + > La J +: The sorption properties of some condensation polymers; poly(galic acid-2,6-diylmethylene), polymer [, poly(piperazine-l,4-diylmethylene), polymer ll, and poly(catechol-3,6-diylmethylene), polymer [1[, toward the trivalent lanthanide metal-ions, La J +, Nd J +, Sm J +, Gd J +, and Tb J + was investigated as a function of contact time, pH, and counter ion by complexometric titration using standard EDTA solution and xylenol orange as an indicator. For the three polymers, the highest metal-ion uptake was achieved at pH 7.0 and by using perchlorate as the counter ion. Re sults of the study revealed that polymer II has the highest metal-ion uptake capacity, and that the metal-ion uptake follows the order: Tb J + > Gd 3 + > Sm J + > Nd 3 +> La 3 + Keyword s: Phenolic-formaldehyde polymers; Lanthanide metal-ion s; Chelation behavior; Counter ion; Piperazine INTRODUCTION studied by several authors and research groups [1- 25]. Vernon [21] has summarized the desirable The sorption properties of chelate-forming properties of a chelating polymer which include: polymers have been the subject of considerable high capacity, high selectivity, fast kinetjcs of current interest [1-4]. In addition, the role played metal-ion uptake, and high mechanical strength by toxic heavy metals in the aquatic environment and durability. [5-7] has stimulated considerable activity and Chelate-forming polymers are produced by interest [1-14] in the development of metal incorporating chelating groups into a polymeric chelating polymers that found widespread use in matrix [2,27]; such chelating groups may be the separation and monitoring of trace heavy covalently bound to a polymer matrix as pendent metal ions, including lanthanides, from aqueous groups or incorporated into the repeating units of solutions [J ,2,12-16]. Interest in chelating the polymer backbone by polymerization of a polymers also stems from the need to separate suitable monomer contammg the required precious metals from aqueous solutions [1, 8, 12, chelating group. Although the condensation of 15, 16]; these polymers have been extensively phenol and formaldehyde is one of the most well- To whom all correspondence should be addressed; Tel.: +962 6 5355000, ext. 2320; Fax: +962 6 5348932; e-mail: mmubarak@ju.edu.jo