UNIVERSITI PUTRA MALAYSIA

SYNTHESIS OPTIMIZATION AND EXTRACTION OF RARE EARTH METAL IONS BY POLY (N - METHYlHYDROXAMIC ACID) RESIN

SECKIN BALCl

FSAS 1998 19

SYNTHESIS OPTIMIZATION AND EXTRACTION OF RARE EARTH METAL IONS BY POLY (N - METHYlHYDROXAMIC ACID) RESIN

By

SECKIN BALel

Thesis Submitted in Fulfi l lment of the Requirements for the Degree of Master of Science in the Faculty of Science & Environmental Studies

Universiti Putra Malaysia May, 1 998

ACKNOWLEDGEMENTS

I extend my deepest thanks to my supervisors Assoc. Prof. Dr. Md. Jelas

Haron and co-supervisor Assoc. Prof. Dr. W. M. Z. Wan Yunus and Dr. Mansor

Ahmad for their invaluable comments and contributions to this study to make it more

efficient, to Mr. Kamal Margona for h is endless support during the analysis with AAS,

Mrs. Choo Chai Syam for her incredible efforts and friendship for I .C .P. analysis and

to Un iversiti Putra Malaysia for its invaluable approach and concerns to create the

best environment for academicians and students.

The deepest thanks are also exlented to Ambassador of Turkish Embassy,

H .E. Ferhat Ataman and h is wife Ayse Ataman, to Commercial Counsellor Mr. Attil la

Gokhan Kizilarslan and his wife Sevda Kizilarslan , to M il itary Attache Captain Oguz

Orh un and h is wife Ayten Orh un for their ful l support and encouragement for me to

do better.

Furthermore, I am very grateful to my spouse dear Ali Balci for an oppertun ity

to l ive in Malaysia and to do Master of Science; and for h is patience and support

econom ically and also spiritually, through out my study. And I also thanks to my dear

mother Mrs. Refika Merder who really help me by taking care of my chi ld,

disregarding her health problems. F inally I would l ike to dedicate my thesis to my

lovely son Yigithan Balci and my spouse Al i SalcL

11

TABLE OF CONTENTS

Page

ACKNOWLEDGEMENTS . . . . . . . , . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . " . . . . ... . . . . . . . . . .. .... . . . . . . . . .. . . ... i i

LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . " . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi

LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . vii

ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix

ABSTRAK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x

CHAPTER

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

I I LITERATURE REViEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Ion Exchange and Chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Types of Ion Exchangers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0

Synthetic Resin Ion Exchangers . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1

Cationic and Anionic Exchange Resin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1

Chelating Ion Exchangers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5

Preparation of Poly(Hydroxam ic Acid) Resin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . 18

Synthesis of poly(N- Substitutedhydroxamic Acid) Resin . . . . . . . . . . . . . . . . . . . 25

iii

Classification of Ion Exchange Methods Used in Analytical Chem istry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Separation of Rare Earth Metal Ions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

III MATERIALS AND METHODS ....................................... ............ 34

Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Preparation of Buffer Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Copolymerization of Poly(Methyacrylate-Divinyl Benzene) . . . . . . 36

Preparation of Poly(Hydroxamic Acid) Resins . . . . . . . . . . . . . . . . . . . . . . . 37

Preparation of Poly(N-Methyl Hydroxam ic Acid) Resin . . . . . . . . . . . . 38

The Classical Visual Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Infrared Spectroscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Hydrogen Ion Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Hydroxamic Acid Group Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Water Content Determination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Capacities of Poly(Hydroxamic Acid) and POly(N-methyl hydroxam ic Acid) Resins for Copper( l l ) and I ron( l I l) Ions . . . . . . . 39

Optimum Conditions for Preparation of Poly(N-methyl hydroxam ic Acid) Resin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40

Stabil ity of the Resin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Sorption Kinetic of the Resin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Sorption Capacity Metal Ions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

iy

Separation of Copper( l l) and I ron( I I I ) . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Separation and Elution of Rare Earth metal Ions . . . . . . . . . . . . . . . . . . . 46

IV RESULTS AND DiSCUSSiON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Confirmation of the Product . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Comparison of POly(N-unsubstituted Hydroxamic Acid) Resin and Poly(N-methyl Hydroxamic Acid) Resin Metal Complexes . . . . . . . . . . 52

Stabil ity of the Resin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Sorption Kinetics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . 62

Separation of Metal Ions by Poly(N-methylhydroxamic Acid) Resin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Separation of Copper( l l) and I ron( l l I ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Distribution Coefficient of the Resin for Rare Earth Metal Ions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Elution of Lanthanum( l l I) and Cerium( I I I ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Separation of Mixture of Rare Earth Elements . . . . . . . . . . . . . . . . . . . . . 73

V CONCLUSiON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , ............... 80

BIBLIOGRAPHy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , ............... 82

APPENDiX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

BIOGRAPHICAL DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . 90

LIST OF PUBLICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

LIST OF TABLES

Table Page

1 . Functional Groups of Some Commercial Ion Exchangers . . . . . . . . .. . . . . . . . . . . . . . . . 3

2. Rare Earth Content in Typical Xenotime ............................................... 31

3. Effect of N-Methylhydroxylam ine Hydrochloride Concentration on Preparation of N-Methyl Hydroxam ic Acid Resin ... . . ... . . . . . . . . . . . . . . . . . . . . . . . 41

4. Effect of Sodium Hydroxide Concentration on Preparation of N-Methyl Hydroxamic Acid Resin . . . . . . . . . .. . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... 42

5. Effect of Amount of Poly(Methylacrylate-Divinyl Benzene) on Preparation of N-Methyl Hydroxamic Acid Resin . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . 43

6. The Water Contents of the Resins Prepared from Different Amount of N-Methylhydroxylamine . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

7. The Water Contents of the Resins Prepared from Different Amount of Copolymer . . . . , " . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . , .. 56

8. Copper Sorption Capacity for Stabil ity Study ... . . . . . . . . .. . ... . . . . . ... . . . . . . ... . . . . . . . 61

9. The Highest Distribution Coefficient Values of Rare Earth Metal Ions and the Respective pH Values . . . . . . . ... . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . . . . . . . . . . . . . ... . . . 69

vi

LIST OF FIGURES

Figure Page

1 . I R Spectrum of P .M.A . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . .. . .. . . . . .. . . . . . . . . . . . . . . . . . . .. . . .. . . . . 50

2. I R Spectrum of NMPHA R .. .. . . . . . . . . . . . .... . ... .. . . .. . . . ... . . . . . . . . . . . . . . . . . . .... . . ... ... 51

3. Sorption Capacity of Cu2+ Ions on Unsubstituted PHA Resin at Various pH .................................................................. 53

4. Sorption Capacity of Cu2+ Ions on PNMHA Resin at Various pH ................ 54

5. Sorption Capacity of Copper(l l ) for the Resins Prepared Using Various Amount of NaOH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

6. Sorption Capacity of Copper(I I ) for the Resins Prepared Using Various Amount of PMA .......................................................... 59

7. Sorption Capacity of Copper(l l ) for the Resins Prepared Using Various Amount of N-Methylhydroxylamine Hydrochloride .............. 60

8. Effect of Shaking Periods on the Copper( l I ) Sorption Capacity of the Poly(N-methylhydroxamic Acid) Resin ........................... 63

9. Sorption Capacities of Copper ( I I ) and I ron ( I I I) of PHA and P(N-methyIHA) Resins ............................................................. 65

1 0. Separation of Copper ( I I ) from I ron ( I I I ) by poly(N-methyl HA)R . . . . . . . . . .. . . . . . . . . .. . . . . . . . . . . . . . . ... . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . 66

1 1 . Distribution Coefficient for Rare Earth Metal Ions at Various pH . . . . . . . . . . . .. . . 68

1 2. Elution of La3+ at pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

1 3. Elution of Ce3+ at pH 1 ..................................................................... 72

1 4. Elution of y3+, Sm3+, La3+ and Nd3+ at pH 2 ............................................ 75

\"11

15. Elution of Gd3+, Vb3+ , Pr3+, Ce3+ and Dy3+ at pH 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

16. Separation of V3+ and Sm3+ at pH 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

17. Separation of V3+ and Nd3+ at pH 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... 78

18. Separation of Sm3+ and La3+ at pH 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

,-iii

Abstract of thesis presented to the Senate of Universiti Putra Malaysia in fulfilment of the requirements for the degree of Master of Science.

SYNTHESIS OPTIMIZATION AND EXTRACTION OF RARE EARTH METAL IONS BY POLY (N-METHYLHYDROXAMIC ACID) RESIN

By

SECKIN BALCI

May 1 998

Chairman: Associate Professor Md Jelas Haron, Ph.D.

Faculty: Science and Environmental Studies

Poly(N-methyl hydroxamic acid) resin was synthesized from crosslinked

poly(methacrylate-d ivinyl benzene). The optimum amounts of N-

metylhydroxylam ine hydrochloride, NaOH, poly(methacrylate) were 2.2 g, 4 g and

and 4 g, respectively and 20 ml water-ethanol solution (75%) was used. The

reaction was completed at room temperature, for 24 hours. The abil ities of poly(N-

methylhydroxamic acid) resin and poly(N-unsubstituted hydroxamic acid) resin to

form complexes with Cu ion were compared. Kinetics study carried out indicated

that metal sorption process by the resin is fast and it is suitable to be used in

column technique. The resin showed good stabi l ity in buffer pH 4 and 1 M HCI

solution . Metal sorption capacities were determ ined for Cu, Fe, Y, La, Ce, Sm , Vb,

Nd, Pr, Dy and Gd. Separations of Cu / Fe, Y / Sm , Y / Nd, Sm / La have been

carried out.

ix

AOsual\ tesis yan9 dikemukakan kepada Senat Universiti Putra Malaysia sebagai memenuhi keparluan untuk ijazah Master Sa ins.

PENGOPTIMUMAN SINTESIS DAN PENGEKSTRAKAN ION LOGAM NADIR BUMI OLEH POLI(ASID N-METIL HIDROKSAMIK) RESIN

Oleh

SECKIN BALCI

May 1998

Pengerusi: Profesor Madya Md Jelas Haron, Ph.D.

Fakulti : Sains dan Pengajian Alam Sekitar

Resin poli (asid N-meti l h idroksamik) telah d isintesis daripada

poli (metakralik-divini l benzena) berangkai si lang. Jum lah optimum �

meti lh idroksi lamina h idroklorida, NaOH, poli(metakrilat) adalah masing - masing

2.2 g, 4 9 dan 4 9 dan 20 ml larutan air - etanol (75 %) digunakan. Tindak balas

d ilakukan pada suhu bi l ik selama 24 jam . Keupayaan resin poli(asid �

metilh idroksam ik) and poli(asid h idroksam ik) untuk membentuk kompleks dengan

ion Cu d ibandingkan . Kajian kinetik menunjukkan bahawa proses serapan logam

oleh resin adalah pantas dan sesuai untuk digunakan dalam teknik turus. Resin

menunjukkan kestabilan yang tinggi dalam larutan pen imbal pH 4 dan larutan 1 M

HCI . Muatan erapan logam ditentukan untuk Cu, Fe, Y, La, Ce, Sm, Vb, Nd, Pr,

Oy dan Gd. Pemisahan , Cu / Fe, Y / Sm, Y / Nd, Sm / La juga dilakukan.

x

CHAPTER I

INTRODUCTION

The phenomenon ion exchange which usually involves either inorganic or

organic ions in predom inantly aqueous solutions is a process involving the

reversible exchange of ions in solution with ions taken by a sol id ion - exchanging

material without perceptible permanent change in the structure of the solid.

Therefore, ion exchange can be any material that has the abil ity to uptake ionic

species from a solution with the simu ltaneous release of a chem ically equivalent

number of ions into solution .

The importance of the ion exchange however, is com ing from its widely

used area that provide the h ighest exchange capacity and is of greatest interest in

the laboratory as wel l as in industrial applications. They are used in many

chemical processes, including simple or chromatographic separations, catalysis

and analytical chem istry. Ion exchange processes are also employed in

hydrometallurgy and metal recoveries, the manufacture of sugar, in pharmacy and

medicine as wel l as in biochem istry and biotechnology, agricu lture and food

processing.

Within the framework of enrich ing economic and commercial activities

among the companies and countries, the current trend of these activities

2

influences the chemical industry and their researches. Scientists and researchers

have concentrated on some segments of chemical industry which are more

commercial as wel l as with scientific concerns. One of these segments is the

production of ion exchanger which is used in certain sectors such as nuclear

technology, electroplating industry, the sweetener industry, pharmacy, medicine,

biochem istry, biotechnology, analytical chem istry, homes, laboratories and small

industries, water treatment, treatment of drinking water and metal recovery.

Ion exchangers have been d istributed commercially under various trade

names: Allasion , Amberlite, Chempro, De-Acidite, Diaion, Dowex, Duolite, Imac,

lonac, Kastel, KatexlAnex, Lewatit, Liquonex, Mykion , Permutit, Purolite, Varion ,

Vionit, Wofatit, Zeo-Karb, Zerolit. Functional groups for some of these ion

exchangers are g iven in Table 1 (Dorfner, 1 99 1 ) .

Although hydroxamic acid ion exchange resin is sti l l not commercially

available today, many researches have been concentrated on th is type of resin,

especially on the various synthesis methods, within the last few years. A

successful experiment to produce hydroxamic acid resin was achieved in 1 965

where it was formed from a commercial carboxylic acid by esterification and then

treatment with hydroxylamine. The product was confirmed with visual tests

through the formation of complex by vanadium (V) and iron ( I I I ) ions. Furthermore,

infrared spectrometry also confirmed the presence of hydroxam ic acid groups in

the product. However, the conversion of carboxylic group to hydroxamic was

found to be very poor (only 3.9 %) (Petry et a I . , 1 965) .

Table 1 : Functional Groups of Some Commercial Ion Exchange Resins

Functional Group

Tertiary am ine

Quaternary ammonium

Amidoxime

Carboxylic acid

Mercaptane

Sulfonic acid

Amino-diacetic acid

Carboxymethyl

Diethylam inoethyl

Commercial Name

Duolite A 303, Lewatit AP 49, Lewatit M P 62

Duolite A 132, Duolite A 1 61 , Duolite A 1 62

Duolite ES 346

Duolite C 433, Duolite C 464, Duolite 468

Duolite ES 465

Duolite C 20, Duolite C 225, Duolite C 204 F

Dowex A 1 , Chelex 1 00, Amberlite IRC 71 8

Serva CM 23, Serva CM 32 Serva CM 52

Serva DEAE 23 SH, Serva Serva DEAE 23 SN, Serva DEAE 23 SS

3

4

Earlier two simi lar methods were used to synthesis this type of resin. I n one

method, carboxylic acid was first converted into the acid chloride and then used to

produce the (hydroxam ic acid) resin. The product was a bifunctional cation

exchanger with carboxylic acid and hydroxam ic acid (Cornaz et aI . , 1 957). In the

other method, a l inear hydroxamic acid resin was produced by hydroxylam inolysis

of poly (methyl acrylate) and hydroxylam ine in the presence of sodium methoxide

and benzene (Kern and Shulz, 1 957). These explorations of synthesis of

(hydroxamic acid) resin indicated that the synthesis method could be improved by

using a methacrylic acid - methylacrylate copolymer as this wou ld prevent the

formation of a hydride. A series of synthesis methods were studied by using

cross-linked polymer and commercial carboxyl ic acid as a starting material and

then used for the column operation. The resin synthesized sti l l contained

carboxylic acid groups because of the difficu lty in formation of the acid ch loride

intermediate (Vernon and Eccles, 1 975).

Mandez and Pil lai (1 990) prepared the resin from styrene maleic acid

copolymer via the four step reactions through the formation of carboxylic acid and

acid ch loride.

The (hydroxam ic acid) resin was also synthesized by a one-step reaction

by Wan Yunus (1 980). The resin , which was in microporous microbead particles,

was shown to be effective in the kinetics of metal sorption. The same method of

one step reaction was also exam ined with different starting chern icals were

poly(ethyl acrylate-divinyl benzene} (Wan Yunus et aI., 1 988 and Lee and Hong,

1 994) and poly(methyl acrylate-divinyl benzene) (Haron et a I . , 1 994).

5

The resins were used to separate n ickel from cobalt and for iron ( I I I )

-copper-cobalt separation (Haron et a I . , 1 994). gold from silver (Vernon and Wan

Yunus, 1 981 ) . zinc from cadmium and, cobalt from copper and n ickel (Shah and

Devi, 1 987) and uranium from neodymium (Mohammed, 1 987). The resins had

also been successful ly used for the recovery and separation of uranium and iron

from the simulated synthetic and real sea water (Vernon and Shah , 1 983; Vernon

and Eccles, 1 976b) .

Three different hydroxam ic acid resins which are N-methyl, N-phenyl and

N-unsubtituted were prepared from a commercial poly(styrene-divinyl benzene)

Amberlite (XAD-4) and their properties were compared (Phi l l ips and Fritz,

1 982).The resins showed good stabil ity and the capacities were not affected by

treatment with 2 M hydroch loric acid or 1 M ammonium hydroxide. (N­

methylhydroxamic acid) resin was synthesized by substituting N­

methylhydroxylammonium chloride via a four step reaction . The (N­

methylhydroxam ic acid) resin was found to have the h ighest metal capacity and

formed the most stable complexes with copper, alum inum , and thorium metal

ions. The extractions of nineteen metal ions including rare earth such as europium

and lanthanum were studied by using (N-methylhydroxamic acid) resin. The

results showed, the resin extracted 50 % of the ions at d ifferent pH values. This

indicate that the poly(N-methyl hydroxamic acid) resin can be used to separate

rare earth metal ions. However, the product sti l l contained carboxylic acid (Ph il l ips

and Fritz, 1 982) .

6

Wan Yunus et al. ( 1 986) described an alternative method of preparing the

poly(N-methyl hydroxamic acid) resin by hydrolysing poly(carboxylic acid-d ivinyl

benzene) . The preparation reaction was completed in 2 steps. In this study.

poly(methacrylate) was used as a starting polymer to prepare poly(N-Methyl

hydroxamic acid) resin. It was reported that the h ighest hydroxamic acid capacity

was obtained from poly(methacrylate) . Thus capabil ity of (N-methyl hydroxamic

acid) resin to sorb metal ions cou Id have been increased by appropriate method

and starting polymer.

The aims of this study are to synthesis a chelating polymer containing

(N-methylhydroxam ic acid) as a functional group from cross-linked

poly(methylacrylate--divinyl benzene). to compare the performance of (N­

unsubstituted hydroxam ic) and (N-substituted hydroxam ic acid) ion exchange

resins, to determine the abil ity of the resin to sorb rare earth metal ions which are

great econom ic important and copper and iron which are contained in the natural

or industrial sources and to separate several rare earth metal ions. and copper

from iron by the resin.

CHAPTER II

LITERATURE REVIEW

Ion Exchange and Chemistry

Ion exchangers is the name given to insoluble electrolytes containing labi le

ions that easily exchange with other ions in the surrounding medium without any

major physical change occurring in the electrolytes' own structure. The process

taking place is usual ly cal led the ion exchange reaction and the labile ions in the

ion exchangers exchange reversibly. The ion exchanging electrolyte is in general

of a macromolecule of complex nature. Since after d issociation, al l electrolytes

exist only as either cations or anions, the ionic sites present in a macromolecu lar

matrix in the case of ion exchangers can also only be either cationic or anion ic.

Thus the different matrices consisting of repeating units in the macromolecules,

such as inorganic materials, highly complex organic materials of natural origin,

and the comparatively simple·structured synthetic resins, carry an electrostatic

charge in the form of a surplus charge or a fixed ion which is neutralized by the

charge of the labile ion . These counter ions are cations in a cation exchanger and

an ions in an an ion exchanger.

7

8

The term ion exchange has often been closely related to or even used

synonymously with adsorption and absorption. Exchange-adsorption was used

instead of ion exchange during the transition in understanding from base

exchange to modern cation exchange or anion exchange. It is important first to

d istinguish between absorption and adsorption before one can identify ion

exchange.

Absorption refers to a uniform penetration of the component of a system

into the solid absorbing material following the old chemical rule of "similia

similibus solvuntur " ( l ike l ikes l ike) and with no change in concentration.

Absorption is thus a process in which the solid engulfs another substance by

d istributing it very even ly throughout its own entire structure. The term adsorption

on the other hand refers to the interaction of a solute with a sol id adsorbent

through physical forces associated with the solid, resulting in a change in

concentration of, e.g. , a particular dissolved component of a system which occurs

mainly at the surface of the solid. Adsorption is thus characterized by an increase

in concentration, which takes place at the interface of the l iquid carrying the solute

and the solid adsorbent. Adsorption and absorption can be denoted as sorption

processes. Here, although the term adsorption for an ion exchange process may

appear strange, phenomena associated with ion exchange have involved

mechanisms other than the ion ic exchange of ions.

Today, the term ion exchangers denotes insoluble polymeric or

macromolecu lar substances with fixed ions. The reactive groups are dissociable

and either present by nature in a natural ly occuring exchange material or have

9

later been incorporated during the manufacture of a synthetic ion exchanger. Ion

exchangers are therefore reactive polymers or reactive macromolecules, but this

term does not include macro-ions. In the case of ion exchangers as reactive

polymers, the reactive groups are not functional, neither in the sense of the

definition of functional groups in organic chemistry nor as defined in polymer

chemistry. It is by reactions of polymers that ion exchangers can usually easily be

obtained, and these are then cal led reactive polymers. The fixed ions or reactive

ionic groups of ion exchangers have the ability of undergoing ion ic exchange

reactions, but they are also able to store ionic species as counter- ions.

Ion exchange is a phenomenon or process involving the reversible

exchange of ions in solution with ions held by a solid ion-exchanging material , in

which there is no directly perceptible permanent change in the structure of the

solid. An ion exchanger can be any material that has the abil ity to uptake ionic

species from a solution with the simultaneous release of a chemical ly equivalent

number of ions into this solution . These materials include cellu lose, dextran and

agarose derivatives, clays and clay minerals, materials based on coal and other

organ ic natural products, synthetic l iquid ion exchangers and ion exchange

membranes. While all the types just mentioned are of greater or lesser uti l ity, in

special applications, in this text by 'ion exchanger' is meant synthetic ion

exchange resin, if not otherwise stated.

10

Types of Ion Exchangers

Ion exchange was first investigated with inorganic materials and found

some industrial use, but were almost completely displaced by synthetic ion

exchange resins. The demand for ion exchange materials that wou ld satisfy the

most diverse requirements led to the development of new products, which must

be considered as separate ion exchanger types according to their special

properties.

Among the available types, synthetic ion exchange resins are of the

greatest importance. But inorganic ion exchangers should not be neglected, since

these have once again aroused interest because of their mechanical, thermal and

chemical properties and because, in l ight of their m ineralogical parallels, they offer

information about numerous processes in soil science. The cel lu lose ion

exchangers represent a separate type with their own characteristics related most

closely to another group. Both types have been rapidly accepted in ion exchange

chromatography where they have become indispensable for analytical as well as

preparative work. I n addition, ion exchangers based on carbon have been

produced and, together with a number of other materials with ion exchanging

properties, have been investigated for their appl icabi l ity. Liquid ion exchangers, as

another type, probably are important primarily because of the technological

possibil ities they offer.

11

Synthetic Resin Ion Exchangers

For the description of properties of synthetic ion exchange resins, three

factors are decisive: The raw material which is used for the construction of the

skeleton or the matrix, bridging agents for crosslinking and insolubil ization , and

the type and number of the ionogenic groups. Synthetic ion exchange resins

chemically are insoluble poly-electrlytes with a h igh but not unl imited moisture

regain capacity. With regard to their function one speaks of cation exchangers,

anion exchangers, and chelating ion exchanger types.

I n principle, polymerization and polycondensation can in principle be used

as the synthesis routes to form the matrix. At the present time, polymerization

resins have become more important than polycondensation resins, as they have a

h igher chemical and thermal stabil ity.

Cationic and Anionic Ion Exchange Resin

One of the most starting material is styrene which is polymerized with itself

and with d ivinylbenzene into a polymeric molecule:

-CH - CH - CH - CH - CH - CH -2 2 2

CH - CH -

I 2

- CH - CH - CH - CH -2 2

12

Incorporation of functional groups such as -S03H , -COOH and -P03H into

the pendant benzene rings in the matrix produce a cationic ion exchange resin.

Where else anionic exchange resin is produced when functional groups such as -

NCH30H, -N H (CH2)2 0H or -NH3

0H is incorporated into the benzene rings.

Another important starting materials for ion exchanger are acrylic

compounds such as acrylic acid, methacrylic acid, acrylic acid ester or

acrrylonitrile. For example acrylic ion exchange resins was made by suspension

polymerization of methacrylic acid and divinyl benzene according to the following

equation (Dorfner, 1 991 ) :

CHa I C=CH2 + I COOH

CHa I

- C - CH - CH - CH -2 2

I COOH

- CH - CH -2

13

A simi lar ion exchanger can also be synthesized from an acrylic ester

fol lowed by hydrolysis of the copolymer (Dorfner, 1 991 )

H I C- CH

b�o� + Polymerization

.

Hydrolysis

14

f CH - CH2-+------ CH - CH2 -

L booH n

- CH - CH -2

A resin prepared from an acrylic molecu le eleminates same interaction of

an aromatic matrix, as in the resin prepared from styrene, especially with the

sample contain ing an aromatic components.

The degree of homogeneity of ion exchange structures depends on the

purity, nature and properties of the starting materials used for their production, as

well as on optimum conditions of polymer synthesis. In spite of irregu lar structure

of the matrix it is possible to produce ion exchangers with a uniform distribution of

the ionic groups. The ever-increasing experimental data of recent years suggests

that the heterogeneity of ion exchangers is sti l l a d ifferent nature, and at the

molecular level of polymer chem istry it is basically associated with the structure of

in itial copolymer.

Cross-linking naturally depends first of al l on the quantity of d ivinylbenzene

used as the cross-linking agent in production. Commercial ion exchangers of the

gel type contain nominally between 2 and 1 2% divinylbenzene (Dorfner, 1 991 ) .