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Modifications of copper-montmorillonite by fatty hydrazides synthesized from palm oil were carried out. Copper-montmorillonite was prepared by cationic exchange process of sodium montmorillonite and copper ions from CuCl2 or CuSO4 in an aqueous solution. The copper contents being 0.03mmol/g before and 0.45mmol/g after ion exchange process for Cu-MMT1 detected by atomic absorption spectrophotometeric indicate that copper ions from the aqueous solution were successfully exchanged with the sodium ion in the clay gallery. Conversion of copper-montmorillonite by fatty hydrazides into the organoclay was carried out by stirring the copper-montmorillonite in hydrochloric acid solution of fatty hydrazide. The formation of organoclay was characterized by XRD, FTIR and Elemental analyses. The XRD study confirms the formation of organoclay by increasing the basal spacing from 1.24 to 3.52nm. The FTIR spectroscopy showing absorption peaks at 3220 and 1600 cm-1 attributed to NH and C=O stretching respectively confirms the presence of fatty hydrazides in the modified clay. The elemental analysis results show that nitrogen content increases in line with the suggestion that the fatty hydrazides are incorporated with the montmorillonite.
Clay minerals attract a great deal of attention from a very wide range of scientific and industrial fields because of natural abundance and exhaustless potentials . Organic modification of clay minerals is a conclusive step in preparing different types of advanced materials. Actual interest is seen to coordinate the clay minerals for preparing nanocomposites and to produce new materials with catalytic , optical  and electronic functions . Plenty works were widely involved with the exchange adsorption of heavy metal cations by clay minerals due to environmental interests to prevent heavy metal pollution . The quantity of multivalent heavy metal cation adsorbed often increases the CEC of the clay mineral because multivalent cation rather to link by equimolar than equivalent exchange .Moreover the heavy metal ions able to precipitate at the surface in the shape of hydroxyl carbonates, hydroxides or other basic salts . In general immobilization of Cu2+,Cd2+,Zn2+ and also Ni2+ but not Pb2+ in any extent can be performed by using poly(hydroxyl aluminum)smectite. The effect of immobilization of each metal ion take place over a particular PH range: 4-6 for Cu2+; 6-8 for Zn2+ and Ni2+ ; and 7-9 for Cd2+ [8-9]. In Cu-montmorillonite there are three different occurrences of Cu2+ ions: majority of the Cu2+ ions replace the original metal ions in the interlayer, or move into hexagonal cavities of Si-O sheet, and small portion penetrate into the octahedral vacancies. This result indicates that there are three different occurrences of Cu2+ ions in montmorillonite: entering into the interlayer, adsorbing in the hexagonal cavities and penetrating into the octahedral vacancies. The first is ascribed to the exchangeable adsorption while the second and the third are attributed to the specific adsorption. When heating the Cu2+ adsorbed montmorillonite occurred causes to move into the hexagonal sites because of lose coordinated water of hydrated Cu2+ ions.
Further heating cause to dehydroxylation and penetrating some Cu2+ ions into the octahedral vacancies from the hexagonal cavities. Dehydroxylation assists to migration the Cu2+ ions into the octahedral vacancies . Layered silicates exhibit strong dispersion and cation exchange properties in many media e.g. water and ethanol which is why silicate is good candidate for fabricating nanocomposites . The inorganic interlayer cations replace by cationic surfactants and changes the hydrophilic silicate surface into hydrophobic. The equilibrium between hydrophilic and hydrophobic depends on the length and packing density of the alkyl chains . Hydrazides use as starting materials and intermediates in the synthesis of certain Amides, aldehydes, and heterocyclic compounds that are otherwise difficult to prepare. They have also been used to identify carboxylic acids and to detect carbonyl compounds that form acyl hydrazones in analytical organic chemistry. The reactions between hydrazines and carboxylic acids or their esters are mostly similar to carboxylic acids and esters with amines . Reactions of esters generally require refluxing for a few hours. In the matter of synthesis of isoniazid hydrazine hydrate is refluxed with the ethyl or methyl ester of isonicotinic acid . The hydrazides isonicotinic acid hydrazide or isoniazid thus can be synthesized in presence of lipases. Nowadays fatty hydrazides were prepared from several sources including amide, ester and carboxylic acids . In this paper sodium montmorillonite by the cationic exchange process converted to copper-montmorillonite. We present the preparation and characterization of new organo-montmorillonite by using fatty hydrazides as organic modifier. Fatty hydrazides were applied as intercalation agent by cation exchange process to organically modification of montmorillonite clay.
2.1. Materials and methods
Sodium-montmorillonite (Na-MMT) with a cation exchange capacity (CEC) of 119 meq /100 g was provided by Kunipia-F Ind. Co. Japan. RBD palm oil was supplied by Southern Edible Oil Industry. (M) Sdn. Bhd. Malaysia. Lypozyme (Mucor Miehei Lipase) was purchased from Novo Nordisk, Denmark. Hexane analytical grade was purchased from Sigma, UK. (CuCl2. 2H2O) and (CuSO4. 5H2O) analytical grade were purchased from Merck, Germany. Hydrazine monohydrate (58%) was purchased from Acros Org, USA.
2.1.1 Fatty hydrazide (FH) synthesis
Synthesis of fatty hydrazide was carried out by shaking (5.00g) of palm oil in 17.00 ml of hexane mixed with (8ml) of hydrazine monohydrate which was neutralized by hydrochloric acid (5M) in presence of Lypozyme (0.25g) in a stoppered flask. The shaking process was carried out in a water bath at 40°C and speed of 100rpm for 24h. The mixture was then transfered into hot hexane (2000ml) and filtered to remove the Lypozyme. The organic phase was then separated from the water phase by using a separation funnel. The product in hexane was then stored in a refrigerator at a temperature up to less than 5°C. The obtained FH was then filtered and dried in vacuum desiccators and stored in a freezer.
2.1.2 Preparation of Cu-MMT
Preparation of Cu-MMT was performed by cation exchange process as previously also reported by Ma et al(2004) where, Na+ ions in the MMT structure was exchanged with Cu+2 ions. Na-MMT (42.02g) was first transfered into 400ml distilled water and vigorously stirred for 1h. Then, 17.05g of (CuCl2· 2H2O) was added to the clay suspension. The mixture was then agitated for 12h at 60°C and allowed to settle for 24h. The supernatant was then discarded and the clay was filtered and washed with distilled water. This washing was repeated until SO4-2 ions in the washing solution could not be detected by (0.1M) BaCl2 solution. The clay was then dried in an oven at 60°C for 24h. The procedure for preparation of Cu-MMT from (CuSO4· 5H2O) is similar to Cu-MMTs from (CuCl2· 2H2O) .The Cu-MMTs from (CuCl2· 2H2O) and (CuSO4· 5H2O) are designated Cu-MMT1 and Cu-MMT2 respectively.
2.1.3 Preparation of organoclay
The synthesis of FH-MMT was also carried out by a cation exchange reaction: Cu-MMT1 (10.00g) was first dispersed in 600ml distilled water by vigorously stirring at 80°C for 1h. The clay suspension was then mixed with 86.00ml of concentrated HCl solution (13.36g) of fatty hydrazide and 1000ml distilled water and continued stirring for 1h. The product was then filtered and washed with distilled water until no chloride as detected with (0.10M) AgNo3 solution. The product was then dried in an oven at 60°C for 24h. The clay was then ground to 75micron or less particles. This procedure was used for Cu-MMT2 preparation. The products were designated FH-Cu-MMT1 and FH-Cu-MMT2 respectively.
X-Ray Diffraction Analysis (XRD) on samples was performed to evaluate the d-spacing of clay layers by using Powder X-Ray Diffraction (PXRD-6000, Shimadzu. Japan) with monochromatic Cu Ka radiation (l = 0.154 nm) and an acceleration voltage of 30 kv. Determine the quantitative and qualitative elements the by using Elemental Analyzer (CHNS-932, LECO Corporation. USA) determining the concentration of a particular metal element by Atomic absorption spectrophotometer (Perkin-Elmer-2380. England) and in addition to determine the functional groups in compounds Fourier transform infrared spectrophotometer (FTIR 1650 Spectrum BX. Perkin-Elmer. England) were applied. Thermal characterization of samples was carried out by thermogravimetric Analysis (TGA) using (Thermo gravimetric Analyzer TGA7. Perkin-Elmer, England).
3. Results and discussion
3.1. X-ray diffraction of the organo-montmorillonite
Figure 1 shows XRD patterns of Na-MMT, Cu-MMT1, and Cu-MMT2. The basal (d001) spacing of Na-MMT, Cu-MMT1 and Cu-MMT2 calculated by XRD result were 1.26, 1.24 and 1.24nm respectively which corresponded to original structure of montmorillonite. The shape difference between Na-MMT and Cu-MMT exhibits that intensity decreased and could be due to cation exchange from Na+ to Cu2+ similar to that of Cu-MMT obtained from Ca-MMT  indicating the presence of fully hydrated hexaqua-copper ions in the interlayer of montmorillonite.
Figure 1: XRD patterns of clay (a) Na-MMT, (b) Cu-MMT1 and (c) Cu- MMT2
Figure 2: XRD patterns of modified clay (a) FH-Cu-MMT1 and (b) FH-Cu-MMT2
Figure 2(a) shows the XRD pattern of FH-Cu-MMT1. Two peaks observe that the small one nearly 5.00° corresponds to original Cu-MMT and the sharp peak at 2.51° corresponds to d-spacing of 3.52nm. Figure 2(b) shows the XRD pattern of FH-Cu-MMT2 which is similar to FH-MMT1 and reveals two peaks that the small one nearly 5.00° corresponds to original structure of Cu-MMT and the sharp one at 2.47°correspond to 3.57nm. Thus substantial increasing the d-spacing of modified clay and peak position shifted to a lower angle suggesting that penetrating alkylohydrazide into clay interlayer replacing the copper ions.
3.2. Fourier transforms infrared spectra
Figure 3(a and b) shows the FTIR spectra of Cu-MMT1 and Cu-MMT2 respectively. For Cu-MMT1 a wide range infrared absorption peaks at 3628 and 1638cm‾1 due to the stretching and deformation of the interlayer water of montmorillonite and attributed to OH stretching vibration of montmorillonite. In addition a very strong band observes at 1040cm-1 which corresponds to Si-O-Si stretching vibration of montmorillonite and also two strong absorption bands observe at 534 and 470cm-1 which may be due to Al-O stretching and Si-O bending vibrations of montmorillonite. The description of absorption peaks for Cu-MMT2 is similar to Cu-MMT1.
Figure 3: FTIR spectra of clay (a) Cu-MMT1, (b) Cu-MMT2
Figure 4(a) shows the FTIR spectra of FH-Cu-MMT1. Several new absorption peaks were observed which could describe as follow; the first is a small absorption peak at 3230 cm-1 attributed to the N-H stretching which corresponds to presence of hydrazides group into the clay interlayer. Two new absorption peaks indicated at 2922 and 2851cm-1 which corresponds to C-H asymmetric stretching and C-H symmetric stretching of alkyl group respectively. A new absorption peak shown at 1600 cm-1 that attributed to C=O stretching of hydrocarbon chain and the last peaks at 1488 and 1470cm-1 which corresponds to CH2 plane scissoring related to hydrocarbon chain.
Figure 4: FTIR spectra of (a) FH-Cu-MMT1 and (b) FH-Cu-MMT2
Figure 4(b) shows the FTIR spectra of FH-Cu-MMT2.The description of FH-Cu-MMT2 is similar to FH-Cu-MMT1. The important vibrations for the study of adsorption of amides by clay minerals are NH2 or NH stretching and deformation and C=O stretching. The positions of the NH2 and NH stretching and deformation vibrations in spectra of amides and amine are very similar. Likewise location of the C=O stretching vibration in the spectra of amides is very similar to that in the spectra of carbonyl compounds .
3.3 Elemental Analysis
The concentration of Cu2+ ions for Cu-MMT1 and Cu-MMT2 were 0.287 and 0.355 mg/l respectively calculated from Atomic absorption spectrophotometer results confirms Cu2+ ions properly replaced with Na+ ions. The CEC results of Cu-MMT1 and Cu-MMT2 were 44.7 and 55.9mmol/100g of clay that confirms the cation exchange between Cu2+ and Na+ ions. Furthermore to confirm the presence of alkylohydrazide inside the clay layer elemental analysis by using CHNS was performed. According to Table 1 the increase of the nitrogen content present in the modified clay compared to the unmodified clay reveals the presence of alkylohydrazide in the clay interlayer.
Table 1: Amounts of Nitrogen in unmodified and modified clay
Montmorillonite Interlayer cation %N in the clay Amount of alkylammonium
in the organoclay
based on N content (mmol/g)
Cu-MMT1 Cu2+ 0.16 -
Cu-MMT2 Cu2+ 0.17 -
FH-Cu-MMT1 R-CO-NH-NH3+ 3.39 1.15
FH-Cu-MMT2 R-CO-NH-NH3+ 3.50 1.19
3.4 Thermogravimetric analysis
Thermal analysis of clay minerals investigated on heating records the reaction occurring in the samples such as dehydration, dehydroxylation, and phase transition explains by proper TG and DTG effects .
Table 2: Total weight loss for each step of decomposition of the clay
Sample Weight loss (%) Total weight loss (%)
<200°C 200-500°C 500°C-800°C
Cu-MMT1 13.06 2.62 3.34 19.02
Cu-MMT2 15.29 2.69 3.48 21.46
FH-Cu-MMT1 2.00 51.00 14.70 67.70
FH-Cu-MMT2 1.30 56.40 1.40 59.10
Figure 5(a and b) show TGA and DTG curves of Cu-MMT1 and Cu-MMT2 respectively. Figure 5(a) shows decomposition of Cu-MMT1 in three steps: The first appears at temperature below 200°C attributed to the surface adsorbed water and desorbed interlayer water. The second step appears at around 600°C ascribed to degenerated hydroxyl groups which reveal a loss of bound water in the crystal. This temperature peak explains the thermal stability of MMTs. The third step at around 850°C attributed to the collapse of the MMTs structure that is not completed here.
Figure 5(a): TGA and DTG curves of Cu-MMT1
Figure 5(b) shows TGA for Cu-MMT2 that the description of this curve is similar to Cu-MMT2.
Figure 5(b): TGA and DTG curves of Cu-MMT2
Figure 6(a): TGA and DTG curves of FH-Cu-MMT1
Figure 6(a and b) show the TGA and DTG of FH-Cu-MMT1 and FH-Cu-MT2 respectively. There are three steps in weight loss of each organoclay-montmorillonite. The first and second decomposition steps split into two stages that at around 100°C and 350°C which are principally attributed to the chemical decomposition of the organic compound. The third decomposition step ascribed to dehydroxylation of the clay layers occurs at ca.500 and 600°C. Formation of carbonaceous compounds takes place above 700 °C [18-20].
Figure 6(b): TGA and DTG curves of FH-Cu-MMT2
The TGA and DTG thermograms of FH-Cu-MMT1 and FH-Cu-MMT2 clearly exhibit that the weight losses are due to both dehydroxylation of montmorillonite and degradation of alkylohydrazide group. Table 2 summarizes the results of weight loss due to the heating of the clay and organoclay. The total weight loss of each compound indicates that high weight loss of FH-MMT is due to existence of the surfactant in the clay interlayer. The amount of FH intercalated into the clay based on the weight loss of FH-Cu-MMT1 and FH-Cu-MMT2 is 2.10 and 1.90mmol/g respectively
Increase of Cu2+ ions for Cu-MMT1 and Cu-MMT2 were 0.287 and 0.355 mmol/g respectively detected by atomic absorption spectrometry indicate copper-montmorillonites were successfully performed by ion exchange reaction and copper ions replacing with the sodium ions in the clay galleries. The formation of organoclay by using fatty hydrazides was characterized by XRD, FTIR and Elemental analyses. The XRD study shows that the basal spacing increase from 1.24 to 3.52nm.The FTIR spectroscopy shows absorption peaks at 3220 and 1600 cm-1 attributed to NH and C=O stretching respectively that confirm the presence of fatty hydrazides in the modified clay. The elemental analysis results reveals that nitrogen content of the clay increases from 0.00 to 1.15mmol/g and 1.19mmmol/g suggesting that the fatty hydrazides are incorporated with the montmorillonite.