American Journal of Chemistry

p-ISSN: 2165-8749    e-ISSN: 2165-8781

2014;  4(1): 22-28

doi:10.5923/j.chemistry.20140401.03

Synthesis and Thermal Behavior of Novel Pillared Ө-Type Zirconium Phosphate 1,10-Phenanthroline Zn(II), Cd(II), Cr(III), Fe(III) and La(III) Materials

Sadek Shakshooki, Bashir Elnageh Ali, Samia El-Rais, Mahmood El-Rais

Department of Chemistry, Faculty of Science, Tripoli University, Tripoli, Libya

Correspondence to: Sadek Shakshooki, Department of Chemistry, Faculty of Science, Tripoli University, Tripoli, Libya.

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Copyright © 2012 Scientific & Academic Publishing. All Rights Reserved.

Abstract

Ө-Type zirconium phosphate, Zr(HPO4)21.88H2O, was prepared and characterized. Reaction of 0.1M 1,10-phenanthroline in ethanol with Ө-typeZr(HPO4)21.88H2O, lead to the formation of Ө-typeZr(HPO4)2 (Phen)0.2760.5H2O. Novel pillared materials: Ө-Zr(H)1.1(PO4)2(Phen)0.276(Zn)0.451.1H2O, Ө-Zr(H)1.95(Phen)0.276(PO4)2(Cd)0.051 1.1H2O, Ө-Zr(H)0.5(PO4)2(Phen)0.25(Cr)0.50.45H2O, Ө-Zr(H)0.8(PO4)2(Phen)0.275(Fe)0.41.43H2O, Ө-Zr(H)0.82(PO4)2(Phen)0.275 (La)0.391.3H2O, were prepared and characterized by chemical, X-ray diffraction, thermal analysis and FT-IR spectroscopy. Their metal ions contents were determined. The pillared materials show the increase of their thermal stability which can be related to metal ions effect. These materials can be considered as new solid acid catalysts, inorganic ion exchangers and as ionic conductance materials.

Keywords: Ө-Type Zirconium Phosphate, Pillared Ө- type Zirconium Phosphate - 1,10-phenanthroline

Cite this paper: Sadek Shakshooki, Bashir Elnageh Ali, Samia El-Rais, Mahmood El-Rais, Synthesis and Thermal Behavior of Novel Pillared Ө-Type Zirconium Phosphate 1,10-Phenanthroline Zn(II), Cd(II), Cr(III), Fe(III) and La(III) Materials, American Journal of Chemistry, Vol. 4 No. 1, 2014, pp. 22-28. doi: 10.5923/j.chemistry.20140401.03.

Article Outline

1. Introduction
2. Materials and Methods
3. Results and Discussions
4. Conclusions
ACKNOWLEDGEMENTS

1. Introduction

Tetravalent metal phosphates are very insoluble compounds with good thermal stabilities and high ion exchange capacities[1,2]. The discovery of their crystalline materials[3,4], represent a fundamental step in chemistry of these compounds with general formula α-M(IV) (HPO4)2 H2O, and γ-M(IV)PO4H2PO42H2O, (where M = Ti, Zr, Hf, Ge, Sn , Ce). These materials contain structural POH groups with labile protons. They can exchange their protons with counter ions such as alkali, alkaline earth, transition divalent and trivalent metal ions[1-4] and act as intercalates[1,2 5,6]. Increase attention direct toward their intercalation[5,6], catalytic[7], electrical conductance[8], and sensors[9]. Layered zirconium phosphates have potential applications as inorganic fillers, sorpents and solid acid catalysts[14-16].
This class of compounds can bond themselves to pillaring reactions by metal amine complexes exchanged in their interlayer. Successful pillaring of these type of layered materials can accomplished via amine intercalation reaction [17-21]. They can form complex pillars between the layers as its formation in-situ by ion exchange of transition metal ions and ligand intercalation. As catalysts attracted attention recently and still in their infancy[22-24]. However, to date very little work on pillared materials of layered zirconium and titanium phosphates. In our Laboratory we are carrying out systematic studies on novel lamellar M(IV) phosphates Here we are reporting synthesis and thermal properties of novel of Ө-typezirconium phosphate 1,10-phenanthroline -Zn(II), Cd(II), Cr(III), Fe(III) and La(III) pillared materials.

2. Materials and Methods

Chemicals:
ZrOCl28H2O,H3PO4(85%),CdCl26H2O,1,10-Phenanthroline, HF, HCl (purchased from BDH), Zn(NO3)24H2O, Cr(NO3)3 3H2O (purchased from LTD), Fe(NO3)39H2O (purchased from ERBA) ,NaOH, NaCl (T- Baker), La(NO3)36H2O (purchased from Riedel-de Haen) were used as received. Other reagents used were of analytical grade.
Instruments used for characterization
§ X-ray powder Diffractometer PW/1710 Philips, using Ni-filtered CuKα (λ= 1.5405Å).
§ Nexus 670 FT-IR Nicolet spectrophotometer.
§ Derivatograph MOM-C Budapest, Hungary and Shimadzu TGA-60H TG/DTA.
§ Atomic Absorption Spectrophotometer Alpha4 (SPEX).
§ Perkin-Elmer 2400 automatic elemental analyzer
§ pH Meter WGW 521.
Preparation of Ө-type zirconium phosphate
50ml 0.5M ZrOCl28H2O in 3M HF were mixed with 200ml of (4.6M) H3PO4 in Pyrex round bottom flask (prior to mixing, the solutions were cooled at ~15ºC). The mixture was left at ~15ºC for 3days. The resultant precipitate was washed with distilled water, by addition and decantation of distilled water up to pH3.The resultant product was filtered and dried in air for 72 hrs at room temperature ~25ºC.
Preparation of Ө- type zirconium phosphate- 1,10- phenanthroline
110 ml of 0.1M 1,10 phenanthroline in ethanol were added to 1.5g Ө-type zirconium phosphate, Zr(HPO4)2 1.88H2O, with stirring at room temperature. After complete addition the stirring was continued for 5days at room temperature and 5hrs at 50ºC. The resultant product was filtered, washed with ethanol and dried in air for 48hrs.
Preparation of Ө-type zirconium phosphate-1,10- phenanthrolineZn(II)
To 100mg of Ө-type zirconium phosphate1,10– phenanthroline, 3.5 ml of 0.05 M Zn(NO3)24H2O in HNO3 solution of pH4 solution were added, followed by addition of 3.5 ml of distilled water with stirring at room temperature. The stirring continued for 24hrs at room temperature (~25ºC). The product was filtered , washed with distilled water, an dried in air for 48hrs. The filtrate plus water washing were collected and diluted up to 100 ml.
Preparation of pillared Ө-type zirconium phosphate -1,10- phenanthrolineCd(II)
To 100mg of Ө–type zirconium phosphate-1,10- phenanthroline, 3.5 ml of 0.05M CdCl26H2O in HNO3 solution of pH4 solution were added, followed by addition of 3.5ml of distilled water, with stirring, at room temperature. The stirring was continued for 24 hrs, at room temperature , the product was filtered washed with distilled water and dried in air for 48 hrs. The filtrate plus water washing were collected and diluted up to 100 ml.
Preparation of pillared Ө-typezirconium phosphate 1,10-phenanthroline Cr(III)
To 100mg of Ө- type zirconium phosphate 6 ml of 0.05 M Cr(NO3)33H2O in HNO3 solution of pH4 were added with stirring at room temperature. The stirring was continued for 24hrs. The product was filtered washed with distilled water and dried in air for 48hrs. The filtrate and water washing were collected and diluted up to 100 ml.
Preparation of pillared Ө-type zirconium phosphate -1,10-phenanthroline Fe(III)
To 100mg of Ө-type zirconium phosphate -1,10 phenanthroline 6 ml of 0.05 M Fe(NO3)3.9H2O in HNO3 solution of pH4 were added with stirring at room temperature. The stirring was continued for 24hrs. The product was filtered washed with distilled water and dried in air for 48hrs. The filtrate and water washing were collected and diluted to 100ml.
The above mentioned filtrates plus water washing were kept for atomic absorption analysis for the remaining Zn2+, Cd2+, Cr3+, Fe3+ metal ions.
Preparation of pillared Ө-type zirconium phosphate -1,10-phenanthrolineLa(III)
To 100mg Ө-type zirconium phosphate -1,10- phenanthroline, 6 ml of 0.05 M La(NO3)3.6H2O in HNO3 solution of pH4 were added with stirring at room temperature .The stirring was continued for 24hrs at room temperature. The product was filtered washed with distilled water and dried in air for 48hrs. The filtrate and water washing were collected diluted to 100 ml.( kept for analysis of La3+ ions by EDTA method).
Figure 1. X-ray diffractogram of Ө-type Zr(HPO4)21.88H2O
Exchange capacity
Exchange capacity of Ө-type zirconium phosphate was determined by addition of 25 ml of 0.10 M NaCl solution to100 mg of the material, with stirring for one hour and then titrated with 0.10 M NaOH solution.

3. Results and Discussions

θ-Type zirconium phosphate, Ө-Zr(HPO4)2.1.88H2O, was prepared from reaction of tetravalent zirconium salt and H3PO4 in HF solution. The reaction can be described as:
The resultant product was characterized by chemical, X-ray and thermal analysis and by FT-IR spectroscopy. Its exchange capacity was determined by Na+ ions titration.
XRD
Figure 1 shows the X-ray powder diffraction pattern of the θ-type zirconium phosphate, shows the presence of diffraction maxima with basal spacing equal 9.85Å. The Ө-type materials exhibit lamellar structure. Negatively charged layers are formed by macroanions [Mn(IV)(HPO4)2]2- and protons (H+) bonded to the oxygen adjacent to the anionic layer form positively charged layers. The water molecules occupying crystallographic sites are located almost in the center of interlayer cavities.
FT-IR
FT-IR becomes a key tool to investigate structure of tetravalent metal phosphates[1,2,22].
Figure 2 Shows FT-IR spectrum of Ө-type zirconium phosphate in the range 4000-400cm-1 wave number. The narrow bands at 3604.65, 3434.11cm-1 and band at 1640.39cm-1 are assigned to vibrational modes of H2O molecules, suggest that water molecules are located at well defined crystallographic sites. These bands at 3434.11, 3434.11cm-1 were also attributed to O-H asymmetric modes of interlayer water molecules. The band at 1640.39cm-1 also corresponds to H-O-H bending modes. The broad band at 3147.10cm-1 assigned to (P)OH stretching mode of the hydrogen bond, it had shoulder at 3310cm-1 attributed to O-H stretching coming from symmetry lowering effect of the H2O interlayer molecules. The bands at the region 1273.21-1054.46 cm-1 are assigned as P-O asymmetry stretching of PO4 groups, while a band at 976.33 cm-1 is characteristic to the bonding in plane of the (P-O) bond. The bands in the region 609.14 to 515.39cm-1 ascribed to the presence of δ(PO4) and to vibration of water molecules (609.14cm-1), while the band at 671.64 cm-1 is connected with O-H bond (out of plane). A tentative assignment of various vibration modes is proposed based on previous works preformed in other M(IV) phosphate compounds [1,2,22].
Figure 2. FT- IR-spectra of Ө-type Zr(HPO4)21.88H2O
Exchange capacity
Exchange capacity of Ө-type zirconium phosphate was determined by Na+ ions titration. The titration curve is shown in Figure 3. The exchange capacity found to be equal to 6.2Meq/g The calculated value 6.01Meq/g. The difference is due to partial hydrolysis of HPO4-2 groups due to pH effect.
Figure 3. Na+ ions titration curve of Ө- type of Zr(HPO4)21.88H2O.
TG/DTA Ө-Type zirconium phosphate
Thermal analysis of Ө-type Zr(HPO4)2.1.88H2O is shown in Figure 4, was carried out at temperature range ~25-800℃ in air atmosphere. The heating rate was 10ºC/min. The thermal decomposition exhibits two weight loss stages, the loss of water of hydration followed by POH groups condensation. The final product was ZrP2O7. The thermal decomposition found to follow the same trends of thermal decomposition of tetravalant metal phosphates[1-3,22]. The thermal decomposion was accompanied by endothermic peaks.
Figure 4. TG/DTA of Ө-type of Zr(HPO4)21.88H2O
TG/DTA of Ө-Type zirconium phosphate- 1,10- phenanthroline
Figure 5. TGA/DTA of Ө-Type Zr(HPO4)2(Phen)0.276 0.5H2O
Figure 5 shows the thermogram of the intercalated material Zr(HPO4)2(Phen)0.2760.5H2O. Its thermal decomposition occurs mainly in five stages. The first and second stages are concerned with the loss of water of hydration that occurred between ~40-170℃, followed by melting of the organic ligand, its decomposition and P-OH groups condensation up to 700℃. The total % weight loss found to be equal to 22.47%. The % of the intercalated 1,10-phenanthroline found to be 14.57%, which was found to be in agreement of the summation of its C,H,N elemental contents. The final product was ZrP2O7. The decomposition accompanied by endothermic peaks, The thermal decomposition represented by the following scheme:
where nH2O = water of hydration, L = ,1,10-phenanthroline x = loading of the organic base, H2OSt = the structural water results from POH groups condensation. The thermal behavior of the materials found to follow the same trend of that observed for inclusion products of layered tetravalent metal phosphates[6,7,23,24]. The thermal decomposition of the organic ligand found to super imposed wih POH groups condensation .
Thermal decomposition of pillared materials
The thermal decomposition of the inclusion product can be described as follows :
where nH2O = water of hydration, L = ,1,10-phenanthroline x = loading of the organic base, H2OSt = the structural water results from POH groups condensation, M the mtalion equivalen. The thermal behavior of the materials found to follow the same trend of that observed for pillared materials of layered tetravalent metal phosphates[6,7,23,24]. The thermal decomposition of the organic ligand found to superimpose with POH groups condensation and the oxidation of the metal ions.
TG/DTA of pillared Ө-Type zirconium phosphate -1,10-phenanthroline Zn(II)
Figure 6. TGA/DTA of Ө-type Zr(H)1.1(PO4)2(Phen)0.276 (Zn)0.451.1H2O
Thermogram of pillared compound Zr(H)1.1(PO4)2 (Phen)0.276 (Zn)0.451.1H2O is shown in Figure 6. The thermal decomposition occurs in four stages The first two stages are concerned with the loss of water of hydration up to 200℃. The third and fourth stage are concerned with melting decomposition of the organic ligand and POH groups condensation. The final products were ZrP2O7+(ZnO)0.45. The total % weight loss found to be equal to 21.534%.
Elemental (C,H,N) analysis related to 1,10- phenanthroline found, C=11.79, H =0.65, N=2.28 of total 14.72%. Its calculated value from TGA analysis was 13.72%. So the TGA can be easily correlate for 1,10 –phenanthroline % contents , due to TGA is a good tool for formulation of such type of pillared materials[6,7,24]. The thermal decomposition of the pillared material was accompanied by endothermic peaks at 59.89, 153.81, 340.20 and 514.5oC .
TG/DTA of pillared Ө-type zirconium phosphate 1,10-phenanthroline Cd(II)
Figure 7. TGA/DTA of Ө-type Zr(H)1.95(PO4)2(Phen)0.276 (Cd)0.051.1H2O
Figure 7 shows the thermogram of Ө-Zr(H)1.95(PO4)2 (Phen)0.276(Cd)0.0511.1H2O. The thermal decomposition found to occur in four stages. The first two stages concern with the loss of water of hydration up to 200℃, with two endothermic peak at 59.43 and 152.23℃, followed by melting decomposition of the organic ligand and P-OH groups condensation The final products were ZrP2O7+(CdO) 0.051. the total weight loss found to be equal to 24.42%. The calculated value from TGA analysis for 1,10- phenanthrolie found to be equal to13.86% which was found to be in agreement with the summation of its C,H,N elemental contents.
TG/DTA of pillared Ө-type zirconium phosphate -1,10-phenanthroline Cr(III)
Figure 8 shows its thermogram of Zr(H)0.5(PO4)2 (Phen)0.25 (Cr)0.50.45H2O .The thermal decomposition found to occur in four stages, water of hydration loss occurs between 65-180℃, followed by melting decomposition of the organic ligand and POH groups condensation. The thermal decomposition was accompanied by endothermic peaks at 59.89,152.13, 240.12, 351.98 and 464.56℃, with weight loss. The total weight % loss found to be equal 15.144%. The final products were ZrP2O7+Cr0.5O0.75. Elemental (C,H,N) analysis related to 1,10-phenanthroline found ,C =10.0, H = 0.55 and N = 2.1 with total % = 12.6%. The calculated value from TGA analysis for 1,10-phenanthrolie found to be equal to 12.37 %. The thermal decomposition of the resulted pillared material was accompanied by endothermic peaks at 60.50, 181.83, 300, 340, 419.82 and 579.81℃, were accompanied by weight loss.
TG/DTA of pillared Ө-Type zirconium phosphate-1,10- phenanthroline Fe(III)
Thermogram of pillared Zr(H)0.8(PO4)2(Phen)0.275 (Fe)0.41.43H2O is show in Figure 9. The thermal decomposition occurs mainly in four stages. The first two stages are concerned with water hydration loss up to 200oC, followed by organic ligand melting , decomposition and POH groups condensation up to 700℃. The final products were ZrP2O7 +Fe0.4O0.6. The total weight loss found to be equal to 23.393%. The thermal decomposition found to accompanied with endothermic peaks at 56,177.22, 343.06, 411.49,482 and 603.61℃.
Figure 8. Figure 8 :TGA/DTA of Ө-type Zr(H)0.5(PO4)2(Phen)0.25(Cr)0.50.45H2O
TG/DTA of pillared Ө-type zirconium phosphate -1,10-phenanthroline La(III)
Figure 10 shows the thermogram of Ө-Zr(H)0.82(PO4)2 (Phen)0.275(La)0.39.1.3H2O. The thermal decomposition found occur in four stages. The first two stages are concerned with the loss of water of hydration up to 200℃, followed by melting, decomposition of the organic ligand. The final products were ZrP2O7 + La0.39 O0.585. The total weight loss found to be equal to 27.02%. The calculated value from TGA analysis for 1,10-phenanthrolie found to be equal to 14.91% which was found to be in agreement with the summation of its C,H,N elemental contents. As expected, the thermal decomposition of the organic ligand found to superimpose wih POH groups condensation and the oxidation of the metal ions .
Figure 9. TGA/TDA of Ө-Zr(H)0.8(PO4)2 (Phen)0.275(Fe)0.4.1.43H2O
Figure 10. TGA/TDA of Ө-Zr(H)0.82(PO4)2 (Phen)0.275(La)0.39.1.3H2O
The thermal decomposition of Ө-type zirconium phosphate -1,10-phenanthroline and its pillared materials were accompanied with endothermic peaks(figures 5-10).
pillared Ө-Type zirconium phosphate-1,10– phenanthroline and their Zn(II) ,Cd(II), Cr(III), Fe(III) and La (III) compound are complexes formed "in- situ", have been chosen because of their possible applications as solid acid catalysts.
C,H,N data , which are related to 1,10-phenanthroline of Ө-type zirconium phosphate-1,10–phenanthroline intercalated product and its pillared materials, found to correlate with their thermal analysis It was found, that the intercalation of the organic ligand does not alter the symmetry of the phosphate groups and does not change all the acidic sites of the host layers, that is due to “cover effect”.
The resultant materials were formulated according to elemental (C,H,N) analysis, thermal analysis and their metal ions uptake.

4. Conclusions

This study shows that Ө-zirconium phosphates can be obtained by direct precipitation method, the HF method. The formulation of the investigated pillared of Ө-zirconium phosphate is based on a fact that M(IV) phosphates are stable materials and extremely insoluble. The final products from thermal treatment are the pyrophosphates and metal oxides. The pillars formed or when the Ө-zirconium phosphates was used as ion exchangers and intercalate material. i.e. in its counter ions adsorbed forms. The loading of the organic ligand found to be quite low from the direct intercalation of 1,10-phenanthroline., this is due to covering effect. The pillared materials show the increase of their thermal stability which can be related to metal ions effect. These materials can be considered as new solid acid catalysts, inorganic ion exchangers and as ionic conductance materials.

ACKNOWLEDGEMENTS

To Departments of Chemistry, Faculty of Sciences, Tripoli University and Sebha University for providing research facilities, to microanalysis centre of Cairo University for elemental and TGA analysis.

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