HTML / Full Text View Download Manuscript
Nano Progress
Research Article
Cost-Effective Alumina-Polymer Nanocomposite: An Excellent Candidate for the Removal of Heavy Metal Ions from Environmental Samples
C. M. Babu,a R. Balasubramanian,b R. Vinodh,a P. Thirukumaran,b A. Shakila Parveen,b A. Selvamani,c B. Sundaravel d and V. Ramkumar*c
dDepartment of Chemistry, Kalasalingam Academy of Research and Education, Krishnan Kovil, 626126, Tamil Nadu, India.
*Corresponding author E-mail address: srirams27@gmail.com (V. Ramkumar)
DOI: 10.36686/Ariviyal.NP.2019.01.01.001
Abstract: An efficient solid phase extraction method has been demonstrated for the removal and preconcentration determination of Cu (II), Co (II), Mn (II) and Cd (II) by using a new adsorbent material, alumina modified polyethylene glycol (PEG) nanocomposite (PEG-Al2O3). Flame atomic absorption spectroscopy (FAAS) was used to determine the concentration of metal ions adsorbed by PEG-Al2O3. Physically adsorbed metal ions from PEG-Al2O3 were initially eluted by using hydrochloric acid and the resultant solution was tested by FAAS. Various adsorption conditions such as effect of pH, amount of adsorbent, preconcentration time, elution time, volume of aqueous phase, and concentration of metal ion were optimized. High metal up-take was found providing this order: Cu (II) > Co (II) > Mn (II) > Cd (II) due to the strong contribution of surface loaded polyethylene glycol. Metal ions, (Cu (II), Co (II), Cd (II) and Cd (II)) containing four real samples (sea water, river water, tap water and grape juice) were studied. To our delight, the prepared PEG-Al2O3 nanocomposite was worked well towards the removal of metal ions with an excellent recovery percentage of 98-100%.
Keywords: Alumina; Polyethylene glycol; Nanocomposite; Heavy metals; Preconcentration; Real sample analysis
Publication Details: Received: 06th February 2019; Revised: 11th February 2019; Accepted: 11th February 2019; Published: 18th February 2019
1. Introduction
Trace metals (for example, Cu, Co, Mn and Cd) are widely spread in environment and may easy enter the food chain from the environment.[1,2] Some trace metals are essential elements and play an important role in human metabolism. However, at higher concentrations, the metals are accepted as potentially poisonous.[3] The consideration of hazardous metal ions is an important practice owing to their potential toxic effects on humans, and the adverse impacts on the environment. Therefore, the removal and determination of trace heavy metals in different environmental samples is of great attention to analytical chemists. Flame atomic absorption spectrometry (FAAS) is widely used for the factual determination of heavy metals at trace levels due to its simplicity and lower cost than other instruments. However, there are some limitations in direct determination of heavy metals in environmental samples by FAAS because of matrix interferences and insufficient sensitivity of instrument.[4] To overcome this issue, an initial pre-concentration procedure is frequently required prior to removal and determination of trace metal ions by FAAS. Till date, several pre-concentration techniques such as ion-exchange, co-precipitation, solvent extraction, cloud point extraction and solid phase extraction have been reported for determination of heavy metals at trace levels in various environmental samples such as natural waters, soil and food.[5-14] Solid phase extraction is an excellent separation, removal and preconcentration technique for trace metal ions with advantages for example simplicity, flexibility, and high enrichment factor. Various solid phase materials have been introduced for the preconcentration and separation of heavy metal ions. For example, chemically modified silica gel with aminothioamidoanthraquinone, polyurethane foam functionalized with naphthol, cellulose functionalized with 8-hydroxyquinoline, zeolite, Amberlite XAD-4 coated with dithiocarbamates, carboxylic acid (COOH) bonded to silica gel, 8-hydroxyquinoline anchored to silica gel, silica gel modified by 2,4,6-trimorpholino-1,3,5-triazin, 4,6-dihydroxy- 2-mercaptopyrimidine (DHMP) loaded on activated carbon, naphthalene loaded with tetraoctylammonium bromide and silica gel-polyethylene glycol are reported as adsorbent materials.[15-24] Various adsorbents such as octadecyl functional groups bonded on silica gel, C-18, glycerol-silica gel, chelating adsorbents, Amberlite XAD resins, Chromosorb resins and other sorbents have been demonstrated for adsorption of metal chelates in the preconcentration and separation of metal ions.[25-33] Inorganic solid adsorbents such as alumina, silica and zirconia are well characterized by their high mechanical properties and strong resistivity to thermal degradation as compared to other biosorbents or organic adsorbents. In addition, advantages of alumina are often proved to be an excellent adsorbent for the removal of heavy metals. In fact, the unique properties of alumina such as high surface area, existence in several structures and amphoteric properties are highly commendable.[34,35] The utilization of alumina-based adsorbents for the removal of toxic heavy metals from various matrices has been well studied, and used to determination lead contaminant in drinking waters.[36] In addition, modified alumina-based adsorbents are reported for the efficient removal of various toxic heavy metals from different water samples.[22,37-39]
Herein, a new adsorbent material, alumina modified polyethylene glycol (PEG) nanocomposite (PEG-Al2O3) was prepared and characterized by various technique such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), Ultraviolet–visible spectroscopy (UV-Visible), Fourier-transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The aim of this present work is the removal and preconcentration determination of Cu (II), Co (II), Mn (II) and Cd (II) at trace levels in environmental and food samples prior to their flame atomic absorption spectrometric determinations and introduce a new solid phase extraction method. The method is based on the retention of Cu (II), Co (II), Cd (II) and Cd (II) by alumina modified polyethylene glycol in a batch method, elution by hydrochloric acid solution and measurement by FAAS.
2. Experimental Section
2.1. Materials and Methods
Analytical grade reagents and chemicals, and doubled distilled water were used throughout the study. A stock solution of 1000 µgmL-1 of Cu (II) was prepared by dissolving 0.314 g of (CH3COO)2Cu.2H2O(Merck) in water and diluting to 100 mL in a volumetric flask. Similarly, stock solutions of Co (II), Mn(II) and Cd(II) were prepared by dissolving 0.423 g of (CH3COO)2Co.2H2O, 0.307 g of (CH3COO)2Mn.H2O and 0.237 g of (CH3COO)2Cd.2H2O, respectively. The above stock solutions were standardized by EDTA titration.[21] The test solutions were prepared by appropriate dilution of the above prepared stock solutions. A 0.10 mol L-1 solution of NaOH was prepared by dissolving 2.0 g of NaOH (Merck) in water and diluted to 500 mL in a volumetric flask. Neutral Alumina (Aldrich~150 mesh, 50Å and surface area > 200 m2/g) was activated by treatment with HCl (5 mol L-1) and dried in vacuum at 120 °C. Polyethylene glycol (PEG, Mw = 4000), (Merck) was heated at 50 °C under vacuum for 40 min before use in order to remove traces of moisture.
Analyst (Perkin Elmer) GBC 902 flame atomic absorption spectrometer (Australia) equipped with Cu, Co, Mn and Cd hollow cathode lamps and air-acetylene flame was used for the analysis. The selected wavelengths for determination of Cu, Co, Mn and Cd were 324.8 nm, 240.7 nm, 279.5 nm and 228.8 nm, respectively. Lamp current of 10 mA was used. Slit width of 0.7 nm for copper, manganese, cadmium and 0.2 nm for cobalt, the acetylene flow was 1.5 L min-1 used for the detection of metals. N2 adsorption desorption isotherms were obtained at 77 K on a Belsorp mini, BEL Japan system. Prior to analysis, the samples were pre-treated at 473 K for 2 h under nitrogen atmosphere. The SEM and TEM images of the material were examined by using SEM-JEOL, JSM-5600 and JEOL, JEM 2100 model. FT-IR spectra were recorded from KBr by using Bomem FT-IR spectrophotometer (Canada). UV-Visible spectrophotometer model T90/T90+ PG instruments (London), TGA-DTA model EXSTAR 6000 (JAPAN), A digital pH-Meter model 632 cyber scan (Japan), with a combined glass electrode was used for pH adjustments was used for analysis. All instrumental settings were those recommended by the manufacturer.
![](/webadmin/ckeditor_html/kcfinder/upload/images/AP-NP-2019-02-003%20(R1)/Scheme.png)
![](/webadmin/ckeditor_html/kcfinder/upload/images/Scheme%201.png)
2.2. Preparation of Adsorbent and Test Samples
A 1.3 g of polyethylene glycol was weighed and transferred to a 250 mL conical flask. 100 mL of acetone was then added to the above conical flask and allowed to stir until the complete dissolution of the organic modifier was obtained. To the above mixture, 10.0 ± 0.1 g of alumina was added and the reaction mixture was further stirred for 4h. Finally, alumina modified polyethylene glycol (PEG-Al2O3) were filtered, washed well with 100 mL acetone, 50 mL ethyl alcohol and finally with 50 mL of diethyl ether. The obtained PEG-Al2O3 was dried in an oven at 50 °C for 8 h. Scheme I shows the schematic representation for the preparation of adsorbent.
The collected sea-waster, river-water and tap-water, grape juice samples were filtered through a Whatman filter paper with pore size of 40Å. The pH range adjusted by using 5 mL of hydrochloric acid and 5 mL of sodium hydroxide, stored in polyethylene bottles, kept in the refrigerator before use and filtered prior to use. Samples were analyzed with and without addition of metal ions to perform a recovery test.
Reaction conditions: adsorption was carried out at different values of pH, while keeping the other variables constant. It was found that Cu, Co, Mn and Cd were quantitatively adsorbed on PEG-Al2O3 in the pH range 8. In subsequent studies, the pH was maintained at 7-8. In the case of weight of the sorbent, the reaction conditions were investigated with 4.0 μg of Cu, Co, Mn and Cd, since 4.0 μg is the maximum percentage of metal up take found. The preconcentration time is 3 h, and the elution time is 30 minutes for all the metal ions Cu, Co, Mn and Cd as for the maximum metal uptake result.
2.3. General Procedure
2.3.1. Preconcentration by the Preparation of Polymer Metal Adsorption
0.4 g of dry sorbent (PEG-Al2O3) was gently shaken for 3 h with 100 mL of 10 ppm solution of each metal ion at an appropriate pH value. The concentration of metal ions in the filtrate was then determined by FAAS.
2.3.2 Elution of Metal Ions
The adsorbed metal ions were eluted with 3.0 mL of 2.0 mol L-1 of hydrochloric acid and the concentration of each element in the eluent was determined by FAAS. A blank solution was also run under the same analytical condition without adding any metal ion.
2.3.3. Determination of Metal Ions
Metal ions in the test solution were thus preconcentrated by solid phase extraction method using the PEG-Al2O3 as the solid sorbent. All the preconcentration processes were carried out batchwise. The preconcentrated sample of Cu, Co, Mn and Cd solutions could be tested by FAAS, ICP-MS or ICP-OES. In the present work, elute collected after the elution was analyzed with FAAS for better accuracy. The FAAS instrument used for the metal ion determination was AAnalyst (Perkin Elmer) GBC902.
3. Results and Discussions
3.1. Material Characterization
Alumina-grafted polyethylene glycol has been previously employed as a solid–liquid phase-transfer catalyst. It is proved that the PEG polymeric material could form complexes with cations much like crown ethers.[25] Therefore, polyethylene glycol was easily immobilized on Alumina and used as a new adsorbent for the removal and preconcentration of Cu, Co, Mn and Cd ions. In order to improve the recovery of preconcentration, the effect of various reaction variables was studied and optimized. The percentage of metal ions adsorbed on the adsorbent was calculated from the amounts of metal ions in the starting sample and the amounts of metal ions eluted from the adsorbent.
![](/webadmin/ckeditor_html/kcfinder/upload/images/AP-NP-2019-02-003%20(R1)/Fig%201.png)
![](/webadmin/ckeditor_html/kcfinder/upload/images/Pic%201.png)
TEM and SEM images of fresh Al2O3 and PEG-Al2O3 are shown in Fig.1. The obtained images elucidate the formation of polymer nanocomposite. The SEM image implies the spherical like morphology of Al2O3 and the PEG-Al2O3 composite material exhibits rough surface morphology. The uniform dispersion of Al2O3 in PEG was confirmed by SEM images (Fig. 1a-b). The TEM images of PEG-Al2O3 were showed that the spherical form of Al2O3 nanoparticles were uniformly distributed in the polymer matrix. The particle size of alumina was found to be 20-50 nm. The surface area of the alumina and PEG-Al2O3 was determined by BET analysis. Nitrogen sorption isotherms of Al2O3 and PEG-Al2O3 are depicted in Fig. 2. Both Al2O3 and PEG-Al2O3) showed type IV isotherm with H3 hysteresis loop. This result indicates that the presence of mesoporous with wormhole-like structure. Pure alumina showed surface area was found to be 150 m2/g, whereas, the PEG-Al2O3 showed an improved surface area of 230 m2/g. This is may be due to the much better porous like structure of PEG-Al2O3. This result suggested that the mixing of PEG and Al2O3 nanoparticles enhanced the textural properties to a great extent, which may be beneficial for the metal ion adsorption.
![](/webadmin/ckeditor_html/kcfinder/upload/images/AP-NP-2019-02-003%20(R1)/Fig%202.png)
![](/webadmin/ckeditor_html/kcfinder/upload/images/Pic%202.png)
3.2. Optimization conditions for extraction of metal ions
Several analytical parameters were optimized for effective preconcentration of Cu, Co, Mn and Cd from real samples (Fig. 1. a-f).
3.2.1. Effect of pH on metal ion uptake properties
The pH is a very important parameter for the metal uptake of the adsorbing agents on solid polymeric material (sorbent). The adsorption of metal ions was performed in both acidic and alkaline media. The preliminary investigation showed that the metal ions are retained by the adsorbent in the alkaline solution. The decrease of pH leads to neutralization of surface charge, thus, the adsorption of cations may decrease.[26] Ionization of the adsorbing adsorbent and the stability of the metal-adsorbent adsorption vary, when changing the pH. It was noticed that the metal uptake increased significantly with increasing pH up to 8 and then it was started to decrease after 8h. The adsorbed stability depended strongly on the pH, as the affinity and stability of the adsorption increased. The result indicated that the Cu, Co, Mn and Cd ions was adsorbed selectively to the higher extend over the pH range. As presented in Fig. 3(a) the highest recoveries are obtained for all metal ions at pH 8. Therefore, pH of 8 was selected for further investigations.
![](/webadmin/ckeditor_html/kcfinder/upload/images/AP-NP-2019-02-003%20(R1)/Fig%203.png)
![](/webadmin/ckeditor_html/kcfinder/upload/images/Pic%203.png)
3.2.2. Amount of PEG-Al2O3
The amount of solid phase material is another important factor on the batch studies for quantitative recovery. In order to estimate the optimum adsorbent quantity, the recoveries of Cu (II), Co (II), Mn (II) and Cd (II) were examined by using the adsorbent quantities in the range of 0.1-0.5 g. The results shown in Fig. 3 (b) indicate that quantitative recoveries were achieved when adsorbent quantity was greater than 0.1 g. In the proposed procedure, 0.4 g of the adsorbent was used for further experiments. When the amount of adsorbent increased the metal uptake was also found to be increased. However, the uptake capacity of the adsorbent saturated after it reaches the maximum absorption percentage. The maximum metal uptake was obtained when the amount of PEG-Al2O3 was 0.4 g. By using 0.4 g of adsorbent, it can be reused at least three times without any loss in the adsorbent capacity. The used adsorbents can also be recovered by a simple procedure. Used PEG-Al2O3 was stirred with 100 mL of 5 % hydrochloric acid for 2 h, filtered and dried. The recycled adsorbent can be reused three times without any loss in the sensitivity. As presented in Fig. 3 (b) the ideal recoveries are obtained for all metal ions at 0.4 g. Therefore, 0.4 g was chosen as an optimum amount and adopted for further investigations.
3.2.3. Effect of Preconcentration Time
Preconcentration time was the time allowed for the adsorbent to be in contact with metal ion solution. Both the stirring and digestion processes were included in the preconcentration time. The saturation time for the metal uptake of the adsorbent was obtained by plotting percentage metal uptake against contact time, keeping the initial metal ion concentration constant. The minimum time needed for good enrichment of Cu, Co, Mn and Cd was 3 h. As presented in Fig. 3 (c) the perfect recoveries are obtained for all metal ions at 3 h. Therefore, 3 h was selected for further investigations.
3.2.4. Effect of Elution Time Parameter
The minimum time required to carry out elution of the metal ions from the sorbent is called elution time. The maximum extraction was 40 minutes. A satisfactory eluent should effectively elute theadsorbed metal ions with small volume in order to achieve high enrichment factor. Various acids and organic solvents such as acetone, hexane, ethanol, HCl and HNO3 were tested as the eluent for desorbing metal ions from the adsorbent surface. Among the solvents studied, hydrochloric acid provided higher recovery compared to other solvents. Therefore, the effect of hydrochloric acid concentration was studied. As the results in Fig. 3 (d) show, the highest recoveries were obtained when 0.10-0.25 mol L-1 of hydrochloric acid was used as an eluent. The effect of the volume of the eluent was also studied and 3.0 mL of 0.2 mol L-1 of hydrochloric acid was selected as the optimum value because it was sufficient for quantitative recovery of the metal ions. As presented in Fig. 3 (d) the highest recoveries are obtained for all metal ions at 30 minutes. Therefore, 30 minutes was selected as optimum elution time for further investigations.
3.2.5. Effect of Metal Ion Concentration
The impact of metal ion concentration on the extraction procedure was studied. When the concentration of metal ion increased, the enrichment efficiency increased. However, after reaching the maximum percentage of metal ion uptake, the saturation level reaches and subsequently started decreasing. When the amount of metal ions was high in a particular volume of water, the effective separation of the metal ion increased. As presented in Fig. 3 (e) the maximum recoveries are obtained for all the metal ions at 80 ppm.
3.2.6. Effect of Aqueous Phase Volume
Solutions containing 0.314 g of Cu were diluted from 50 to 500 mL by deionised water and, Cu, Co, Mn and Cd was analyzed by the general procedure. The effect of aqueous volume in batch method was studied with 0.4 g of adsorbent equilibrated at optimum pH for 5 h. It was observed that the adsorption of Cu, Co, Mn and Cd remained constant up to 500 mL. The volume of aqueous phase is an important factor for the adsorption of metals. They indicated that the exchange reaction of Cu, Co, Mn and Cd was rapid and the efficiency was high. As presented in Fig. 3 (f) the concentrated recoveries are obtained for all metal ions at 500 mL.
3.3. Interference Studies
In order to examine the effect of different ions on determination of Cu (II), Co (II), Mn (II) and Cd (II), constant amounts of Cu (II), Co (II), Mn (II) and Cd (II) were taken with different amounts of ions and subsequently the general procedure was followed. Deviation of ±5 % or more from the absorbance value of the standard solution was considered as interference. The results presented in Table 3 show that a large number of ions tested have no effect on determining Cu (II), Co (II), Mn (II) and Cd (II). The effect of interfering ions in real samples concentrate such as NaCl, NaNO3, Na2SO4, KCl, MgCl2, CaCl2 on solid phase extraction were studied. Interfering ions are separately added to the solution containing metals and the present procedure was followed. The matrices contents in the eluent solution were found to be significantly lower and suitable for FAAS determination.
The simultaneous preconcentration of Cu (II), Co (II), Mn (II) and Cd (II) were determined as follows. 100 mL of the solution containing 25 mL of 10 ppm of Cu (II), Co (II), Mn (II) and Cd (II) was prepared and NaOH was used for adjusting pH value. The adsorbed metal ions were eluted with 3.0 mL of 2.0 mol L-1 of HCl and the concentration of each element in the eluent was determined by FAAS and the result shown in the Table S1 (See Supporting Information). A blank solution was also run under the same analytical conditions without adding Cu (II), Cu (II), Mn (II) and Cd (II) ions. Metal up-take was found providing this order: Cu (II) > Co (III) > Mn (II) > Cd (II) due to the strong contribution of surface loaded polyethylene glycol.
Sea Water | River Water | Tap Water | |||||||
Metals | Added Concentration (ngmL-1) |
Found (ngmL-1)
|
Recovery (%) | Added Concentration (ngmL-1) | Found (ngmL-1) | Recovery (%) | Added Concentration (ngmL-1) | Found (ngmL-1) | Recovery (%) |
Cu (II) | - | 6.5 ± 0.2 | - | - | 4.61 ± 0.4 | - | - | 2.5 ± 0.4 | - |
10 | 16.5 ± 0.5 | 100 | 10 | 14.5 ± 0.5 | 99 | 10 | 12.5 ± 0.5 | 100 | |
20 | 26.3 ± 0.3 | 98 | 20 | 24.57 ± 0.3 | 99 | 20 | 22.47 ± 0.3 | 99 | |
Co (II) | - | 4.6 ± 0.3 | - | - | 3.0 ± 0.3 | - | - | 3.3 ± 0.3 | - |
10 | 14.6 ± 0.2 | 100 | 10 | 13.0 ± 0.2 | 100 | 10 | 13.3 ± 0.6 | 100 | |
20 | 24.5 ± 0.6 | 99 | 20 | 22.8 ± 0.6 | 98 | 20 | 23.1 ± 0.6 | 98 | |
Mn (II) | - | 1.2 ± 0.1 | - | - | 2.2 ± 0.3 | - | - | 2.1 ± 0.1 | - |
10 | 11.1 ± 0.6 | 99 | 10 | 12.1 ± 0.6 | 99 | 10 | 12.0 ± 0.5 | 99 | |
20 | 21.1 ± 0.2 | 99 | 20 | 22.2 ± 0.2 | 100 | 20 | 22.1 ± 0.3 | 100 | |
Cd (II) | - | 2.6 ± 0.1 | - | - | 1.1 ± 0.1 | - | - | 0.6 ± 0.1 | - |
10 | 12.5 ± 0.3 | 99 | 10 | 11.1 ± 0.6 | 100 | 10 | 10.4 ± 0.5 | 98 | |
20 | 22.4 ± 0.5 | 98 | 20 | 21.0 ± 0.4 | 99 | 20 | 20.5 ± 0.3 | 99 |
3.4. Removal of heavy metals from environmental samples
The proposed solid phase extraction procedure was applied for the removal and to determine the Cu (II), Mn (II) and Cd (II) ions present in sea-water, river-water, tap-water and grape juice samples. The results are given in Table 1 and 2. Different amounts of the investigated metal ions were also spiked to the samples and the resulting solutions were submitted to the preconcentration procedure. Good agreement was achieved between the added and found concentrations of analytes using the recommended procedure. The recovery values for the analyte ions were in the range of 98-100%. In order to estimate the accuracy of the procedure, these values revealed that there is good agreement between the two methods and there was also no significant difference between the results by performing t-test at 95% confidence limit.
Sample | Metal | Added Concentration (ngmL-1) |
Found (ngmL-1) |
Recovery (%) |
Grape Juice | mn | - | 1.6 ± 0.2 | - |
10 | 11.6 ± 0.6 | 100 | ||
20 | 21.4 ± 0.1 | 98 |
![](/webadmin/ckeditor_html/kcfinder/upload/images/AP-NP-2019-02-003%20(R1)/Fig%204.png)
![](/webadmin/ckeditor_html/kcfinder/upload/images/Pic%204.png)
Composition of Interfering ions (g) | Metals | % up taken in Sea water | % up taken in River water | % up taken in Tab water |
NaCl (0.5), NaNO3 (0.5), Na2SO4 (0.5),KCL(0.5), MgCl2(0.5), CaCl2 (0.5) | cu | 95.1 | 97.9 | 98.2 |
Mn | 92.2 | 94.8 | 96.7 | |
co | 90.3 | 96.7 | 97.2 | |
cd | 86.6 | 92.3 | 94.1 |
3.5. Adsorbent and metal characterization
The PEG-Al2O3 are special type of branched inorganic-organic copolymer which has polyethylene glycol functional groups in the side chains that has been found to be stable to acid, base, high temperature and oxygen. FT-IR spectrum of PEG-Al2O3 (Fig. 4) shows that the presence of -OH and ethylene oxide groups on the surface of the adsorbent.
FT-IR spectrum of PEG-Al2O3 and Al-PEG-Cu was recorded in KBr medium (400-4000cm-1) exhibited a number of band as shown in above spectrum. The tentative assignments of various stretching and bending frequencies in comparison with FTIR absorption bands of PEG-Al2O3 and Al-PEG-Cu listed in Table S2 (in Supporting Information). PEG-Al2O3 shows number of absorption bands and the absorption frequencies are in a slightly shifted position compared with those of the reactants, PEG-Al2O3 and Al-PEG-Metal adsorption. The peak observed at 3416 cm-1 may be assigned to the –OH group. The peak observed 2878 cm-1 indicates the -CH2O (sym) and the peak 1122 cm-1 may be attributed to binding of metal ions on to the adsorbent. FT-IR spectra of Al-PEG-Cu spectrum display the presence of some peaks. The peaks absence at 1122 cm-1, 2873 cm-1 may be assigned due to the formation of Al-PEG-metal ion adsorption. The structurally important absorption frequencies of adsorbent and metal adsorption have been presented in the above UV-visible spectra (Fig. 5). The ligand peak at 527 nm indicates that the PEG adsorbed the metal ions. TGA analysis was conducted to understand the decomposition properties of the modified sorbent and metal adsorbed sorbent. The TGA data for the decomposition of the PEG-Al2O3 and Al-PEG-Metal are shown in Fig. 6. The initial decomposition temperature for both was observed around 30 °C with a sharp decrease in weight being observed around 450 °C. An additional sharp decrease in weight was observed between 30 °C and 450 °C. Metal adsorbed compound is more thermally stable than adsorbent. Fig. 6 & S1 show that weight loss in µg and percentage, Table S3 shows that weight loss of the compounds in percentage.
![](/webadmin/ckeditor_html/kcfinder/upload/images/AP-NP-2019-02-003%20(R1)/Fig%205.png)
![](/webadmin/ckeditor_html/kcfinder/upload/images/Pic%205.png)
![](/webadmin/ckeditor_html/kcfinder/upload/images/AP-NP-2019-02-003%20(R1)/Fig%206.png)
![](/webadmin/ckeditor_html/kcfinder/upload/images/Pic%206.png)
3.6. Sorbent Regeneration
To be viable material for sorbent system they must be chemically stable. The sorbent could be easily regenerated with 1:1 HCl. To obtain sorbent reusability, the sorption-desorption cycle was repeated four times with the same adsorbent. More than 95% of the desorbed metal ions were removed using 1:1 HCl. This revealed the good recyclability and stability of the adsorbent under acidic condition.
4. Conclusions
In this work we showed that the methodical performance of PEG-Al2O3 nanocomposite for preconcentration and removal of trace amounts of Cu, Co, Mn and Cd in sea-water, river-water, tap-water and grape juice samples and simultaneous determination. PEG-Al2O3 nanocomposite represents a potentially significant advancement in the field of preconcentration and analytical separation due to its high surface area, thus making possible free interference preconcentration of Cu, Co, Mn and Cd ions in different matrices. The performance of proposed method was significantly better than that of previous method with respect to preconcentration system, including satisfactory removal and preconcentration efficiency. Moreover the prepared adsorbent is eco-friendly and very economical because it can be recycled and used several times without any loss in the recovery. In addition, the method is simple, precision and no need of organic solvents as eluent. The method is highly sensitive and selective for removal and preconcentration determination of trace amounts of Cu (II), Co (II), Mn (II) and Cd (II) by FAAS. To the best of our knowledge, this is the first report on the PEG-Al2O3 nanocomposite as an adsorbent for the removal and preconcentration of metal ions. The sorbent finds broad applications as preconcentrations and separation matrix for metal ion. It has a superior reusability and stability, the investigated adsorbent has been studied for the quantitative separation of Cu (II), Co (II), Mn (II) and Cd (II) and it may be applied for the removal of other transition metals as well.
Supporting Information
FT-IR and TGA results are provided in the supporting information file.
Acknowledgements
The authors V.R and A.S are greatly acknowledge the DST-SERB-NPDF/2017, New Delhi for providing National Post-Doctoral Fellowship (NPDF) to carry out the research work.
Conflicts of Interest
The authors declare no conflict of interest.
References
- Zhao G.; Huang X.; Tang Z.; Huang Q.; Niua F.; Wang X. Polymer-Based Nanocomposites for Heavy Metal Ions Removal from Aqueous Solution: A Review. Polym. Chem., 2018, 9, 3562-3582. [CrossRef]
- Kyzas G. Z.; Bomis G.; Kosheleva R. I.; Efthimiadou E. K.; Favvasa E. P.; Kostoglou M.; Mitropoulos A. C. Nanobubbles Effect on Heavy Metal Ions Adsorption by Activated Carbon. Chem. Eng. J., 2019, 356, 91-97. [CrossRef]
- Abou El-Reash Y.G. Magnetic Chitosan Modified with Cysteine-Glutaraldehyde as Adsorbent for Removal of Heavy Metals from Water. J. Environ. Chem. Eng., 2016, 4, 3835-3847. [CrossRef]
- Mohammad B.; Hassanlou P. G.; Amini M. M.; Omidi F.; Esrafili A.; Farzadkia M.; Bagheri A. Application of Solvent-Assisted Dispersive Solid Phase Extraction as a New, Fast, Simple and Reliable Preconcentration and Trace Detection of Lead and Cadmium Ions in Fruit and Water Samples. Food Chem., 2015, 187, 82-88. [CrossRef]
- Daneshvar T. G.; Shemirani F. Magnetic Multi-Wall Carbon Nanotube Nanocomposite as an Adsorbent for Preconcentration and Determination of Lead (II) and Manganese (II) in Various Matrices. Talanta, 2013, 115, 744-750. [CrossRef]
- Reza F. H.; Behbahani M. Solid Phase Extraction of Pb (II) and Cd (II) in Food, Soil, and Water Samples Based on 1-(2-pyridylazo)-2-Naphthol-Functionalized Organic–Inorganic Mesoporous Material with the Aid of Experimental Design Methodology. Food Anal. Method, 2015, 8, 982-993. [CrossRef]
- Azzam A. M.; El-Wakeel S. T.; Mostafaa B. B.; El-Shahat M.F. Removal of Pb, Cd, Cu and Ni from Aqueous Solution Using Nano-Scale Zero-Valent Iron Particles. J. Environ. Chem. Eng., 2016, 4, 2196-2206. [CrossRef]
- Nahid P.; Naghdi T. Silicon Carbide Nanoparticles as an Adsorbent for Solid Phase Extraction of Lead and Determination by Flame Atomic Absorption Spectrometry. J. Ind. Eng. Chem., 2014, 20, 3502-3506. [CrossRef]
- Lemos V. A.; Franca R. S.; Moreira B. O. Cloud Point Extraction for Co and Ni Determination in Water Samples by Flame Atomic Absorption Spectrometry. Sep. Purif. Technol., 2007, 54, 349-354. [CrossRef]
- Hitoshi M.; Matsuda Y.; Mori T.; Uehara A.; Ishikawa Y.; Endo M.; Shida J. Visual Colorimetry for Trace Antimony (V) by Ion-Pair Solid-Phase Extraction with Bis [2-(5-chloro-2-pyridylazo)-5-Diethylaminophenolato] Cobalt (III) on a PTFE Type Membrane Filter. Anal. Sci., 2008, 24, 219-223. [CrossRef]
- Koshya N.; Singh D. N. Fly Ash Zeolites for Water Treatment Applications. J. Environ. Chem. Eng., 2016, 4, 1460-1472. [CrossRef]
- Sadeghi M.; Nematifar Z.; Irandoust M.; Fattahi N.; Hamzei P.; Barati A.; Ramezani M.; Shamsipur M. Efficient and Selective Extraction and Determination of Ultra-Trace Amounts of Hg2+ Using Solid Phase Extraction Combined with Ion Pair Based Surfactant-Assisted Dispersive Liquid–Liquid Microextraction. RSC Adv., 2015, 5, 100511-100521. [CrossRef]
- Wang Y.; Wang B.; Wang Q.; Di J.; Miao S.; Yu J. Amino-Functionalized Porous Nanofibrous Membranes for Simultaneous Removal of Oil and Heavy-Metal Ions from Wastewater. ACS Appl. Mater. Interfaces, 2019, 11, 1672–1679. [CrossRef]
- Saravaia H.; Gupta H.; Popat P.; Sodha P.; Kulshrestha V. Single-Step Synthesis of Magnesium-Doped Lithium Manganese Oxide Nanosorbent and their Polymer Composite Beads for Selective Heavy Metal Removal. ACS Appl. Mater. Interfaces, 2018, 10, 44059-44070. [CrossRef]
- Moawed E. A.; El-Shahat M. F. Preparation, Characterization and Application of Polyurethane Foam Functionalized with α-Naphthol for Preconcentration and Determination of Trace Amounts of Nickel and Copper in Cast Iron and Granite. React. Funct. Polym., 2006, 66, 720-727. [CrossRef]
- Kara A.; Tekin N.; Alan A.; Safakli A.; Physicochemical Parameters of Hg (II) Ions Adsorption from Aqueous Solution by Sepiolite/Poly (vinylimidazole). J. Environ. Chem. Eng., 2016, 4, 1642-1652. [CrossRef]
- Elwakeel K. Z.; Al-Bogami A. S. Influence of Mo (VI) Immobilization and Temperature on As (V) Sorption onto Magnetic Separable Poly p-Phenylenediamine-Thiourea-Formaldehyde Polymer. J. Hazard. Mater., 2018, 342, 335-346. [CrossRef]
- Pourreza N.; Zolgharnein J.; Kiasat A. R.; Dastyar T. Silica Gel–Polyethylene Glycol as a New Adsorbent for Solid Phase Extraction of Cobalt and Nickel and Determination by Flame Atomic Absorption Spectrometry. Talanta, 2010, 81, 773-777. [CrossRef]
- Barbara F. Selective Dispersive Micro Solid-Phase Extraction using Oxidized Multiwalled Carbon Nanotubes Modified with 1, 10-Phenanthroline for Preconcentration of Lead Ions. Food Chem., 2016, 209, 37-42. [CrossRef]
- Wittaya N.; Aeungmaitrepirom W.; Tuntulani T. Chemically Modified Silica Gel with Aminothioamidoanthraquinone for Solid Phase Extraction and Preconcentration of Pb (II), Cu (II), Ni (II), Co (II) and Cd (II). Talanta, 2007, 71, 1075-1082. [CrossRef]
- Vieira E.G.; Soares I.V.; Pires G.; Ramos R.A.; do Carmo D.R.; Dias Filho N.L. Study on Determination and Removal of Metallic Ions from Aqueous and Alcoholic Solutions using a New POSS Adsorbent. Chem. Eng. J., 2015, 264, 77-88. [CrossRef]
- Ghaedi M.; Ahmadi F.; Shokrollahi A. Simultaneous Preconcentration and Determination of Copper, Nickel, Cobalt and Lead Ions Content by Flame Atomic Absorption Spectrometry. J. Hazard. Mater., 2007, 142, 272-278. [CrossRef]
- Shamspur T.; Sheikhshoaie I.; Mashhadizadeh M.H. Flame Atomic Absorption Spectroscopy (FAAS) Determination of Iron (III) After Preconcentration on to Modified Analcime Zeolite with 5-((4-Nitrophenylazo)-N-(2′, 4′-dimethoxyphenyl)) Salicylaldimine by Column Method. J. Anal. At. Spectrom., 2005, 20, 476-478. [CrossRef]
- Pourreza N.; Rastegarzadeh S.; Larki A. Simultaneous Preconcentration of Cd (II), Cu (II) and Pb (II) on Nano-TiO2 Modified with 2-Mercaptobenzothiazole Prior to Flame Atomic Absorption Spectrometric Determination. J. Ind. Eng. Chem., 2014, 20, 2680-2686. [CrossRef]
- Jani A. M. M.; Losic D.; Voelcker N. H. Nanoporous Anodic Aluminium Oxide: Advances in Surface Engineering and Emerging Applications. Prog. Mater. Sci., 2013, 58, 636-704. [CrossRef]
- Weiquan C.; Yu J.; Jaroniec M. Template-Free Synthesis of Hierarchical Spindle-like γ-Al2O3 Materials and their Adsorption Affinity Towards Organic and Inorganic Pollutants in Water. J. Mater. Chem., 2010, 20, 4587-4594. [CrossRef]
- Mohammadi S.; Afzali D.; Pourtalebi D. Flame Atomic Absorption Spectrometric Determination of Trace Amounts of Lead, Cadmium and Nickel in Different Matrixes After Solid Phase Extraction on Modified Multiwalled Carbon Nanotubes. Open Chem., 2010, 8, 662-668. [CrossRef]
- Khezeli T.; Daneshfar A. Development of Dispersive Micro-Solid Phase Extraction Based on Micro and Nano Sorbents. Trends Analyt. Chem., 2017, 89, 99-118. [CrossRef]
- Hassanien M. M.; Mortada W. I.; Kenawy I. M.; El-Daly H. Solid Phase Extraction and Preconcentration of Trace Gallium, Indium, and Thallium Using New Modified Amino Silica. Appl. Spectrosc., 2017, 71, 288-299. [CrossRef]
- Mirzaei M.; Behzadi M.; Abadi N. M.; Beizaei A. Simultaneous Separation/Preconcentration of Ultra Trace Heavy Metals in Industrial Wastewaters by Dispersive Liquid–Liquid Microextraction Based on Solidification of Floating Organic Drop Prior to Determination by Graphite Furnace Atomic Absorption Spectrometry. J. Hazard. Mater., 2011, 186, 1739-1743. [CrossRef]
- Khajeh M.; Laurent S.; Dastafkan K. Nanoadsorbents: Classification, Preparation, and Applications (with Emphasis on Aqueous Media). Chem. Rev., 2013, 113, 7728-7768. [CrossRef]
- Baytak S.; Turker A. R. Application of Ram Horn Powder (RHP) for the Preconcentration and Determination of Copper in Various Samples by Flame Atomic Absorption Spectrometry. J. Anal. Chem., 2006, 61, 483-489. [CrossRef]
- Anup J. B.; Gogoi S.; Baruah G.; Dutta R. K. Utilization of Co-Existing Iron in Arsenic Removal from Groundwater by Oxidation-Coagulation at Optimized pH. J. Environ. Chem. Eng., 2016, 4, 2683-2691. [CrossRef]
- Pourreza N.; Zolgharnein J.; Kiasat A. R.; Dastyar T. Silica Gel–Polyethylene Glycol as a New Adsorbent for Solid Phase Extraction of Cobalt and Nickel and Determination by Flame Atomic Absorption Spectrometry. Talanta, 2010, 81, 773-777. [CrossRef]
- Naiya T. K.; Bhattacharya A. K.; Das S. K. Adsorption of Cd (II) and Pb (II) from Aqueous Solutions on Activated Alumina. J. Colloid Interf. Sci., 2009, 333, 14-26. [CrossRef]
- Vunain E.; Mishra A. K.; Mamba B. B. Dendrimers, Mesoporous Silicas and Chitosan-Based Nanosorbents for the Removal of Heavy-Metal Ions: A Review. Int. J. Biol. Macromol., 2016, 86, 570-586. [CrossRef]
- Mazaher A.; Elmongy H.; Madrakian T.; Abdel-Rehim M. Nanomaterials as Sorbents for Sample Preparation in Bioanalysis: A Review. Analytica Chimica Acta., 2017, 958, 1-21. [CrossRef]
- Qiu H.; Yan J.; Lan G.; Liu Y.; Song X.; Peng W.; Cui Y. Removal of Cu2+ from Wastewater by Modified Xanthan Gum (XG) with Ethylenediamine (EDA). RSC Adv., 2016, 6, 83226-83233. [CrossRef]
- Chen J.; Wang Y.; Ding S.; Ding J.; Li M.; Zhang C.; Zou M. Sub-and Super-Critical Water Oxidation of Wastewater Containing Organic and Heavy Metallic Pollutants and Recovery of Superfine Metallic Particles. J. Environ. Chem. Eng., 2016, 4, 2698-2705. [CrossRef]
© 2019, by the authors. Licensee Ariviyal Publishing, India. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
![](../images/gray-bg.jpg)