α- Zirconium Titanium Phosphates - Fibrous Cerium Phosphate Composite Membranes and Their 1,10- Phen...

Sadek K.Shakshooki, Mohamed B.Hassan, Wafaa K.EL-Nowely, Abdulhafiz El-Belazi, Sumaia M. Abed, Mona.M. Al-Said

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α- Zirconium Titanium Phosphates - Fibrous Cerium Phosphate Composite Membranes and Their 1,10- Phenanthroline Cu(II) Pillared Materials

Sadek K.Shakshooki1,, Mohamed B.Hassan2, Wafaa K.EL-Nowely2, Abdulhafiz El-Belazi1, Sumaia M. Abed3, Mona.M. Al-Said3

1Department of Chemistry, Faculty of Science, Tripoli University

2Department of Chemistry, Sebha University, Sebha

3Industrial Research Centre, Tripoli, Libya

Abstract

Nanosized fibrous cerium phosphate, Ce(HPO4)2.2.9H2O(nCePf), and α- Zirconium -Titanium Phosphates, ZrxTi1-x(HPO4)2.H2O(α-ZTP), where x = 0.9, 0.8, 0. 67, 0.34, were synthesized. Novel composite membranes [ZrxTi(1-x)(HPO4)2]0.25 [Ce(HPO4)2]0.75 .3.3H2O were prepared. Reactions of the resulting composite membranes with 1,10-phenanthroline in ethanol, followed by the addition of 0.1M CuCl2.2H2O, in (1:1) ethanol: aqueous solution, lead to the formation of novel pillared materials: [(H1.16) Zr0.9Ti0.1 (PO4)2]0.25[(H1.16 ) Ce (PO4)2]0.75(PhenCu)0.42.2.25H2O, [(H1.5)Zr0.8Ti0.2 (PO4)2]0.25 [( H1.5)Ce (PO4)2] 0.75 (Phen Cu)0.25.1.77H2O, [(H0.3 ) Zr0.67Ti (PO4)2] 0.25 [(H 0.3) Ce (PO4)2]0.75.(Phen Cu)0.85. 4H2O, [(H1.6)Zr0.34Ti0.66 (PO4)2]0.25 [(H1.6) Ce (PO4)2]0.75.(PhenCu)0.2. 2.22 H2O, respectively. They were characterized by chemical, X-ray diffraction (XRD) and thermal analysis (TGA), accordingly were formulated. XRD patterns of the composite materials retain (d) spacing reflection of α-ZTP and nCePf, where d001 = 7.58 Å and 11.38 Å, respectively, The resulting composites are thermally stable and can be considered as novel ecofriendly solid acid catalysts, Ionex changers and ionc conductance materials.

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Cite this article:

  • K.Shakshooki, Sadek, et al. "α- Zirconium Titanium Phosphates - Fibrous Cerium Phosphate Composite Membranes and Their 1,10- Phenanthroline Cu(II) Pillared Materials." Physics and Materials Chemistry 2.1 (2014): 7-13.
  • K.Shakshooki, S. , B.Hassan, M. , K.EL-Nowely, W. , El-Belazi, A. , Abed, S. M. , & Al-Said, M. (2014). α- Zirconium Titanium Phosphates - Fibrous Cerium Phosphate Composite Membranes and Their 1,10- Phenanthroline Cu(II) Pillared Materials. Physics and Materials Chemistry, 2(1), 7-13.
  • K.Shakshooki, Sadek, Mohamed B.Hassan, Wafaa K.EL-Nowely, Abdulhafiz El-Belazi, Sumaia M. Abed, and Mona.M. Al-Said. "α- Zirconium Titanium Phosphates - Fibrous Cerium Phosphate Composite Membranes and Their 1,10- Phenanthroline Cu(II) Pillared Materials." Physics and Materials Chemistry 2, no. 1 (2014): 7-13.

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1. Introduction

Layered tetravalent metal phosphates with alpha and gamma structures bear resemblance to clay minerals [1, 2, 3] Their general formula are α-M(IV)(HPO4)2. H2O, θ-M(IV)(HPO4)2. 5H2O and γ-M(IV). PO4. H2PO4.2H2O (where M = Ti, Zr, Hf, Sn, Ge, Ce). Their structures have been established [4, 5, 6].

Earlier investigations on intercalating properties of layered α and γ-zirconium phosphates have demonstrated that coordination compounds can be formed between the layers of α-and γ-zirconium phosphates, able to coordinate in situ transition metal ions such as Cu(II), Ni(II), Co(II) and Pd(II) [7, 8]. These compounds found to behave as catalysts [7, 8, 9]. Results confirmed the formation of transition metal ions-phenanthroline complex species between the layers [7, 8, 9].

Synthetic membranes can be fabricated from a large number of different materials. It can be made from organic or inorganic materials including solids such as metal or ceramic, homogeneous films (polymers), heterogeneous solids (polymeric mixes, mixed glasses), and liquids. Ceramic membranes are produced from inorganic materials such as aluminum oxides, silicon carbide, and zirconium oxide. Their inorganic composite membranes are well known [10, 11, 12, 13].

Inorganic membrane-membrane composites are not a recent invention. Hundreds of scientific papers and few reviews on inorganic membrane composites, examples; SiO2-TiO2, SiO2-ZrO2, Pd-γAl2O3, Pd thin film deposited on ceramic materials, from metal complexes, from metal alloys, P-type zeolite membrane on porous -alumina, Pd-Cu membranes supported on ZrO2, mesoporous silica membranes containing iron oxide nanocrystallites, γ-A12O3-T iO2, and ZrO2 etc., were published [11, 12, 13, 14]. Most of these type of inorganic membrane composites are prepared by sol-gel method, electrochemical vapour deposition and by chemical vapour deposition metal alloy in gas phase [14, 15, 16, 17].

In our laboratory we are undertaking systematic investigations on new inorganic ion exchange membranes of tetravalent metal phosphates and their transition metal ions-organonitrogen heterocyclic pillared materials, that were prepared by different methods.

Here we are reporting synthesis and characterization of novel α-Mixed zirconium-titanium phosphates-fibrous cerium phosphate composite membranes and their 1,10-phenanthroline Cu(II) pillared products.

2. Materials and Methods

2.1. Chemicals

ZrOCl2.8H2O, TiCl4, CeSO4.4H2O, H3PO4 (85%), CuCl2.2H2O of BDH. Other reagents used were of analytical grade.

2.2. Instruments Used for Characterization

•  X-ray powder Diffractometer PW/1710 Philips, using Ni-filtered CuKα (λ= 1.5405Å).

•  Scanning electron microscopy (SEM) Jeol SMJ Sm 5610 LV

•  Nexus 670 FT-IR Nicolet spectrophotometer

•  Derivatograph MOM-C Budapest, Hungary and Shimadzu TGA-60H TG/DTA.

•  UV-Visible spectrophotometer, Spectronic

•  Atomic Absorption Spectrophotometer Alpha 4 (SPEX)

•  pH Meter WGW 521.

2.3. Preparation of Nanofibrous Cerium Phosphate, Ce(HPO4)2.2.9H2O (nCePf)

100ml of 0.05M CeSO4.4H2O in 0.5M H2SO4 solution were added drop wise to 100ml of 6M H3PO4 at 80oC with stirring. After complete addition the resultant material left to digest at that temperature for 5h.To that one liter of hot distilled water, (~60°C), was added with stirring for 1h. The resulting fibrous cerium phosphate was subjected to washing by re-slurring several times with distilled water up to pH 3.5, filtered, washed with ethanol and dispersed in distilled water (2 liters), and kept in form of slurry aqueous solution.

2.4. Preparation phosphate α-ZrxTi(1-x)(HPO4)2 .H2O(α-ZTP)

Crystalline mixed α-zirconium-titanium phosphates, α-ZrxTi(1-x)(HPO4)2.H2O (α-ZTP), were prepared, according to method that was reported by shakshooki etal [18], from refluxing Their parent amorphous materials ZrxTi(1-x)(HPO4)2 .3H2O, in 10 M H3PO4 for 100h.

2.5. Preparation of [α-ZrxTi(1-x)(HPO4)2]0.25[Ce(HPO4)2]0.75 Composite Membranes

The composite membranes [α-ZrxTi(1-x)(HPO4)2]0.25[Ce(HPO4)2]0.75.3.3H2O were prepared from reactions of slurry aqueous solution of α-ZrxTi(1-x)(HPO4)2.H2O with slurry aqueous solution of fibrous cerium phosphate in wt/wt % mole ratio 1:3, respectively. Typical preparation, 0.25g α-ZTP slurry aqueous solution + 0.75g nCePf slurry aqueous solution were used.

2.6. Exchange Capacities Determination of α-ZTP and nCePf and Their Composite Materials

To 100 mg of the material 25 ml of 0.1M NaCl solution were added, stirred for 1h, followed by titration with 0.1 M NaOH solution with stirring.

2.7. Estimation of Titanium

Titanium contents in the resulting materials was determined spectrophtometerically as described earlier [18].

2.8. Preparation of Novel [α-ZrxTi(1-x) (HPO4)2]0.25[Ce(HPO4)2]0.75.nH2O1,10- phenanthroline Cu(II) Pillared Materials

The novel pillared materials were prepared from reactions of the composites [α-ZrxTi(1-x) (HPO4)2]0.25[Ce(HPO4)2]0.75.3.3H2O membranes (0.25g) with (30ml) 0.1M 1,10-phenanthroline in ethanol with stirrings for 24h at room temperature and for 5h at 60˚C, followed by the addition of (15ml) 0.05M CuCl2.2H2O aqueous solution to the resultant 1,10-Phenanthroline inclusion composite products.

2.9. Estimation the Uptake of Cu2+ Metal Ions

The uptake of Cu2+ metal ions were determined from the analysis of the original metal ions concentration and on its non equilibrated solution by atomic absorption spectrophotometer.

3. Results and Discussion

Nanofibrous cerium phosphate membrane, Ce(HPO4)2.2.9H2O(nCePf), was prepared and characterized by chemical, XRD, TGA, FT-IR and by scanning electron microscopy (SEM).

3.1. XRD

XRD of nanofibrous cerium phosphate membrane is shown in Figure 1, with d001 = 10.89Å.

Figure 1. XRD of nanofibrous cerium phosphate
3.2. TGA

The thermal analysis of nanoCe(HPO4)2.2.9H2O was carried out at temperatures between 10-775°C. Its thermogram is shown in Figure 2. The final product was CeP2O7, results from the loss of water of hydration between 60-200°C, followed by POH groups condensation. The total weight loss found to be equal to 19.09%.

3.3. FT-IR

FT-IR become a key tool to investigate structure of tetravalent metal phosphates. Figure 3, shows FT-IR spectra of fibrous Ce(HPO4)2.2.9H2O, with a trend similar to that of M(IV) phosphates. It consists of broad band centered at 3350cm-1 assigned to vibrational modes of H2O molecules, suggest that water molecules are located at well defined sites, also attributed to an O-H asymmetric modes of water molecules. Small sharp band at 1628cm-1 is related to H-O-H bending, and sharp broad band centered at 1045cm-1 is corresponds to phosphate groups vibration The bands at the region 630-450 cm-1 are ascribe the presence of δ(PO4) and to vibrational of water molecules.

Figure 3. FT-IR spectra of nanofibrous cerium phosphate
3.4. SEM

SEM morphology image of the nanosized fibrous ceriumphosphate(nCePf) is shown in Figure 4. The photograph shows its average size is ~20.5 nm.

Crystalline α-mixed zirconium-titanium phosphates α-ZrxTi(1-x)(HPO4)2.H2O (where x = 0.9, 0.8, 0.67, and 0.34) were prepared and characterized by XRD, TGA, and by FTIR Spectroscopy. The materials found to be α-layered type materials.

3.5. XRD

Figure 5 shows typical X-ray diffractogram of mixed zirconium titanium phosphates, Zr0.8Ti0.2(HPO4)2.H2O, with basal spacing( d001) = 7.56Å.

3.6. TGA

The investigated samples found to have similar thermal decomposition mechanism, consisting of the following stages:

•  Loss of crystalline water (water of hydration) up to 200ºC.

•  Loss of the structural water due to POH groups condensation, start to occur >300ºC.

•  Finally formation of pyrophosphates of general formula [ZrxTi(1-x)]P2O7 at ~650-700ºC.

Typical thermogram of zirconium titanium phosphates, α-Zr0.8Ti0.2(HPO4)2.H2O, is shown in Figure 6. The thermal decomposition found to occur in two stages. which concern with the loss of water of hydration between 70-200°C, followed by POH groups condensation. The total weight loss found to be equal to 12.32 %, the final product was ( Zr0.8Ti0.2) P2O7.

3.7. FT-IR

Figure 7 shows typical FT-IR spectrum of mixed zirconium titanium phosphates, α-Zr0.8Ti0.2(HPO4)2.H2O, with a trend similar to the FT-IR spectra of tetravalent metal phosphates. Two sharp bands at ~3600, 3500 cm-1 and band at 1638 cm-1are assigned to vibrational modes of H2O molecules, suggest that water molecules are located at well defined crystallographic sites. The bands at ~3600, 3500 cm-1 were also attributed to an O-H asymmetric modes of interlayer water molecules. The band at 1638 cm-1 also corresponds to H-O-H bending modes. The bands in the region 608-510cm-1 ascribed to the presence of δ(PO4) and to vibrational of water molecules, follow trend similar to the FT-IR spectra of tetravalent metal phosphates [18, 19].

3.8. Ion Exchange Capacity
Figure 8. Na+ ions titration curve of α-Zr0.8Ti0.2(HPO4)2.H2O

Figure 8 shows typical Na+ ions titration curve of α-ZrxTi(1-x)(HPO4)2.H2O, and found to follow similar trend to that of crystalline layered mixed zirconium-titanium phosphates [18].

3.9. [α-ZrxTi(1-x)(HPO4)2]0.25 [Ce(HPO4)2]0.75 Composite Membranes

The composite membranes [α-ZrxTi0(1-x)(HPO4)2]0.25[Ce(HPO4)2]0.75.3.3H2O were prepared and characterized. The resultant composites were flexible homogeneous thin films with good mechanical properties. Its XRD, FT-IR and TGA are shown in Figure 9, Figure 10, Figure 11, respectively.

3.10. XRD

Figure 9 shows typical X-ray diffraction pattern of composite [α-Zr0.8Ti0.2 (HPO4)2]0.25[Ce(HPO4)2]0.75.3.3H2O with d spacing reflections at 11.38Å, 7.58Å, which are related to α-Zr0.8Ti0.2(HPO4)2.H2O and fibrous cerium phosphate, respectively, found to be typical for the X-ray patterns expected for such type of composite materials, where the composite materials retain their XRD patterns of their parent materials.

Figure 9. FT-IR spectra of [α-Zr0.8Ti0.2 (HPO4)2]0.25[Ce((HPO4)2]0.75.3.3H2O
3.11. FT-IR

Figure 10 shows FT-IR spectrum of the typical composite [α-Zr0.8Ti0.2(HPO4)2]0.25 [Ce(HPO4)2]0.75.3.3H2O, with a trend similar to that of M(IV) phosphates [18]. It consists of broad band centered at 3400cm-1 which is due to OH groups symmetric stretching of H2O, small sharp band at 1630cm-1 is related to H-O-H bending, and sharp broad band centered at 1030cm-1 is corresponds to phosphate groups vibration The bands at the region 600-450 cm-1 are ascribe the presence of δ(PO4).

Figure 10. FT-IR spectra of [α-Zr0.8Ti0.2 (HPO4)2]0.25[Ce((HPO4)2]0.75.3.3H2O
3.12. TGA

Thermogram of typical composite membrane [α-Zr0.8Ti0.2(HPO4)2]0.25 [Ce(HPO4)2]0.75.3.3H2O is shown in Figure 11. The thermal decomposition occurs in three stages. First two stages concern the loss of hydrated water of hydration between 65-300 oC, followed by POH groups condensation up to 750 oC. Total weight loss was 20.42 %. Found to be in agreement with formulation of the composite material. The final products were (α-Zr0.8Ti0.20)0.25] P2O7 and [(Ce) 0.75]P2O7.

Figure 11. TGA of [α-Zr0.8Ti0.2(H)1.5(PO4)2]0.25[Ce(H)1.5(PO4)2]0.7.5.3.3H2O
3.13. Novel Pillared Materials

[(H1.16) Zr0.9Ti0.1 (PO4)2]0.25[(H1.16) Ce (PO4)2]0.75(PhenCu)0.42.2.25H2O, [(H1.5)Zr0.8Ti0.2 (PO4)2]0.25 [( H1..5)Ce (PO4)2] 0.75 (Phen Cu)0.25.1.77H2O

[(H0..3 ) Zr0.67Ti (PO4)2] 0.25 [(H 0..3) Ce (PO4)2]0.75.(Phen Cu)0.85.4 H2O, [(H1.6)Zr0.34Ti0.66 (PO4)2] 0.25 [(H1.6 ) Ce(PO4)2]0.75.(PhenCu)0.2.2.22 H2O

were prepared and characterized by chemical, TGA analysis and FT-IR spectra. Their Cu2+ions content were determined by atomic absorption spectroscopy.

The resulting pillared products are porous materials where the divalent transition metal ions exchanged with the H+ of the POH groups and the organic ligand inserted in the interlayer region, where the presence of metal ion and the ligand act as pillars, that facilitate the access to the interlayer region of different reactants.

This pillaring process gives rise to porous solids can be tailor made by suitable choosing of the layered inorganic material [17]. Thermal analysis, TGA, is a good tool for characterization of M(IV) phosphates and their intercalated materials [6, 18, 19, 20], where at high temperature combustion of the complexes occurs to give the M(IV) pyrophosphate (in case of M(IV) phosphates) and M(IV) pyrophosphate + M oxide, in case of intercalated complex materials. So it is easy to formulate the product according to equations shown below:

a

b

(Where y= exchanged proton, Lx= ligand loading, n= water of hydration and z= metal ion mole content).

From the (a, b) the weight losses can be calculated. The content of metal ions was determined by atomic absorption spectroscopy analysis [20].

3.14. TGA of Pillared Materials

Figure 12 shows the thermogram of pillared compound [α-Zr0.9Ti0.1 (HPO4)2]0.25 [Ce(HPO4)2]0.75 (Phen Cu)0.42.2.25H2O. The thermal decomposition found to occur in 3 stages. First stage concern with the loss of water of hydration up to ~180ºC, followed by organic ligand decomposition and POH groups condensation as well as the formation of CuO, up to ~760ºC.

The thermal decomposition of the organic ligand and oxidation of Cu ions found to superimpose to that of the POH groups condensation. The final products were [(Zr0.9Ti0.1)0.25(Ce)0.75]P2O7 + (CuO)0.42. The total weight loss found to be equal to (28.98 %), the calculated value was (28.766%).

Figure 12. TG/DTAof [(H1.16) Zr0.9Ti0.1 (PO4)2]0.25[( H1.16 ) Ce (PO4)2]0.75 (PhenCu)0.42.2.25H2O

Figure 13 shows the thermogram of pillared compound [α-Zr0.8Ti0.2(H)1.5(PO4)2]0.25[Ce(H)1.5(PO4)2]0.75 (PhenCu)0.25. 1.77 H2O. The thermal decomposition found to occur in 3 stages. first stage is relating to the loss of water of hydration up to~180ºC, followed by organic ligand decomposition and POH groups condensation, as well as the formation of CuO, up to~760ºC. The final products were [(Zr0.8Ti0.2)0.25(Ce)0.75]P2O7 + (CuO)0.25. The total weight loss found to be equal to (23.01 %), the calculated value was (23.03%).

Figure 13. TG/DTA of [(H1.5)Zr0.8Ti0.2 (PO4)2]0.25 [( H1..5)Ce (PO4)2] 0.75 (Phen Cu)0.25.1.77H2O

Thermogram of [α-Zr0.67Ti0.33(H)0.3(PO4)2]0.25 [Ce(H)1.5(PO4)2]0.75 (Phen Cu)0.85.4H2O, is shown in Figure 14. The thermal decomposition found to occur in three stages. The first stage concerns the loss of water of hydration up to ~180ºC, followed by organic ligand decomposition and POH groups condensation, and the formation of CuO, up to ~760°C. The final products were [(Zr0.67Ti0.33)0.25(Ce)0.75]P2O7 + (CuO)0.85. The total weight loss found to be equal to (41.13 %), the calculated value was (40.78 %).

Figure 14. TGA/DTA [(H0..3 ) Zr0.67Ti (PO4)2]0.25[(H0..3)Ce (PO4)2]0.7 (Phen Cu)0.85.4 H2O

Figure 15 shows the thermogram of the pillared [α-Zr0.34Ti0.66(H)1.6(PO4)2]0.25[Ce(H)1.6(PO4)2]0.75(PhenCu)0.2. 2.2H2O. The thermal decomposition found to occur in 3 stages. first stage concerns the loss of water of hydration up to ~180°C, followed by organic ligand decomposition and POH groups condensation, as well as the formation of CuO, up to ~760°C. The final products were [(Zr0.34Ti0.66)0.25(Ce)0.75]P2O7 + (CuO)0.2. The total weight loss found to be equal to (22.56 %), the calculated value was (23.16 %).

Figure 15. TG/DTA of [(H1.6)Zr0.34Ti0.66 (PO4)2]0.25[(H1.6) Ce(PO4)2]0.75 (PhenCu)0.2.2.22 H2O

4. Conclusion

This study shows that α-zirconium titanium phosphates-nanofibrous cerium phosphate composite membranes can be obtained by mixing slurry aqueous solution of their parent materials in required wt / wt % mixing ratios. The resultant composites were flexible homogeneous thin films with good mechanical properties. XRD of the composites show that it is possible to obtain tailor made inorganic membrane-membrane composites, where their XRD patterns show two d spacing reflections which are related to the d spacing reflection of their parent compounds. i.e. their XRD retain the d spacing of their parent materials. The formulation of the investigated pillared materials is based on a fact that M(IV) phosphates are stable materials and extremely insoluble. The final products from thermal treatment are the pyrophosphates. The titanium % contents found to retain its molar ratio in hydrogen form, in pillars forms or when the materials used as ion exchangers, i.e. in its counter ions adsorbed forms. The pillared materials shows 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.

Aknowledgement

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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