- Email: [email protected]
polyacrylamide hydrogel
Available online at www.sciencedirect.com
ScienceDirect Materials Today: Proceedings 12 (2019) 529–535
www.materialstoday.com/proceedings
NCMD 2018
Removal of methyl orange over TiO2/polyacrylamide hydrogel Anil Barak, Yash Goel, Raj Kumar and S.K. Shukla* Department of Polymer Science, Bhaskaracharya College of Applied Sciences, University of Delhi, Delhi-110075, India
Abstract The present work describes the preparation of titanium oxide impregnated polyacrylamide hydrogel (TiO2/PAM) by in-situ polymerization technique. The prepared hydrogel was characterized by fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and x-ray diffraction (XRD) techniques. The physical properties (solvent content, swelling behaviour, porosity) of hydrogel were also studied by ASTM method. Further, results are revealing the formation of composite hydrogel with improved properties. Thus, obtained prepared hydrogel was used for removal of methyl orange dye from laboratory prepared water samples. The methyl orange removal efficiency and kinetics was evaluated by UV-Visible spectroscopy in different conditions. The results indicate the improvement in dye removal capacity due to impregnation of metal oxides in hydrogel matrix. © 2019 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of National Conference on Materials and Devices (NCMD - 2018)
Keywords: Hydrogel, Physical properties, Methyl orange removal, Water purification
1. Introduction The use synthetic dyes in different industries such as paints, textiles, printing inks, pharmaceuticals, food, cosmetics, plastic, photographic and paper industries are increasing exponentially. It is estimated that ~ 7 × 105 tons of synthetic dyes and pigments are annually used in industries across the world [1-2]. Out of total use of dyes, about 40,000–50,000 tons of dyes are discharged in water bodies from natural or anthropogenic means. The increase of dyes contents are creating several problems like interference in penetration of sun rays in water bodies, increasing harmful chemicals and disturbing oxygen balance [3-4]. The photodegradtion of dyes in water bodies also produces several harmful chemicals with carcinogenic nature [5]. These secondary pollutants are consumed by aquatic organisms, which are further bio magnified and leads serious problems along with theft to several aquatic organism. *
Corresponding author: Tel. 091-11-25087595; Email: [email protected]
2214-7853 © 2019 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of National Conference on Materials and Devices (NCMD - 2018)
530
Barak et al. / Materials Today: Proceedings 12 (2019) 529–535
Thus, it is important to design a appropriate methods to remove and control the dyes from water bodies. Some important methods used for removal of dyes are adsorption, photo- oxidation, chemical precipitation, reverse osmosis and electro decomposition. However, the efficacy of all the methods are depends on available water purifying materials like adsorbents, membrane, photo-catalysts and hydrogel [6-7]. Further, hydrogel are water insoluble, cross linked, three-dimensional polymers with huge capacity of holding water their chain networks. It is because the presence of hydrophilic functional groups in the polymer backbone along with cross-links between network chains. In this regards several bio and petro polymers cellulose, alginate, chitosan and acrylamides are used for preparing hydro gel. Among the different hydrogel the acrylamides (AAM) based hydrogels are found of considerable interest in water purification due to their high mechanical strength, adsorption capacities, regeneration abilities and capability of being reused for continuous processes. The addition of metal oxides in hydrogel has been offers several advantageous properties like strength, adsorption sites and photo catalysis. Several metal oxides in incorporated hydro gel are used for water purifications for different pollutants [8-9]. However, the potential of material is indicating more intensive application for properties and applications [10]. In this context, the present study reveals the synthesis of zinc and titanium oxide incorporated poly-acrylamide hydrogel and its application in removal methyl orange from artificial water sample. The structure and properties of hydro gel are also discussed along with its mechanism of dye removal. 2. Experimental 2.1. Chemicals Acrylamide (AM) as monomer (99.5% ), Potassium peroxy disulfate (99.5%) as initiator, N,Nmethylenebisacrylamide (NMBA) as cross linker from E- Merk and Titanium Oxide (99.8%) from LOBA chemical were procured and used as such. AR grade solvents and double distilled water were used during entire investigation. 2.2 Synthesis of hydrogel In a typical experiment, 2g of acrylamide was polymerized in 20 ml distilled water using 200mg K2S2O8 along with 150 mg TiO2 after stirring on a magnetic stirrer for 1 hour at 50oC. After 30 minutes 50 mg cross-linker was also added. The stirring was continued for another 20 minutes, which yields a white precipitate of TiO2 incorporated polyacrylamide hydrogel. The solution was filtered and gel was transferred to a petridish, which was dried in a vacuum oven and stored for further characterization and applications. 2.3 Characterization 2.3.1 Physical Characterization Water adsorption, swelling index, porosity and bulk density of hydrogel was evaluated by standards ASTM methods. Initially the hydrogels were cut into pieces of 0·5 cm3 size by using a surgical blade. The samples were immersed in 100 ml distilled water at room temperature for 24 hours to reach swelling equilibrium, which resulted in the adsorption of water inside the network of hydrogels, and then the weight was taken. The samples were dried in a vacuum oven to remove interstitial water at 40°C and 4 mm mercury (Hg) pressure for 48 h and the weight was measured. The change in the thickness of hydrogel samples was measured with a digital Vernier calliper [11]. The calculation for water uptake was made using Eqn 1 and swelling behaviour by Eqn 2:
m(%)
m2 m1 100 (1) m1
where m1 is the mass of the dry specimen and m2 is the mass of the specimen after water adsorption.
T (%)
h2 h1 100 (2) h1
where h1 is the thickness (mm) of the dry hydrogel specimen and h2 is the thickness (mm) of the hydrogel after water immersion. Porosity is the measurement of void space in a material in which air or solvent can be introduced
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and it is determined as the volume of water incorporated in the cavities per unit membrane volume using water uptake data discussed above. The calculation was made by Eqn 3:
Porosity
Wetweight Dryweight (3) Area length densityofwater
Further, bulk density of the hydrogel was determined by measuring the dimensions and weights of five samples. The size was measured with the help of a Vernier calliper. Three samples were tested for each experiment, and the average density was reported. 2.3.2. Structural characterization The chemical structure of hydrogel was evaluated by Bruker: Alpha model fourier transform infrared spectrometer. The spectra were recorded in the potassium bromide (KBr) phase after 16 scans at resolution of 4 cm−1 in the range of 4000–500 cm−1. The particle phase and crystallinity was estimated with the help of a Rigaku Rotaflex, Rad/Max-200B powder X-ray diffractometer using Cu Kα radiation with λ =1·5405 Å at a scanning rate of 2°/min. However, surface morphology of the synthesised materials was examined through a Hitachi-3700 scanning electron microscope operating at 20 kV. The samples were sputter-coated with a thin layer of gold before taking photographs to avoid charge accumulation. 2.3.3 Removal of dye The dyes removal capacity of hydrgel was estimated after recording the UV spectra of dyes solutions on a JASLO V-670 Spectrophotometer. Initially, aqueous solution of methyl orange was prepared by dissolving dye in requisite amount of water. Further, the 4 mL of solution was then taken in 3 different test tubes A, B and C. In tube A was left as reference while in B and C 200 mg of hydrogel piece was added. The sample B was kept in identical condition of A i.e ambient condition. However, test tube C was kept under the exposure of UV radiation in UV chamber. After the time interval of the 90 minutes (fig 2) solution was pipette out and UV-visible spectra were recorded in the wavelength range of 180-800 nm. 3. Results and discussion 3.1 Preparation of hydrogel The change in colour sequence and precipitation is indicative for the formation of impregnated hydrogels in the presence of TiO2 by free radical polymerisation [12]. The physical parameters of hydro gel are given in Table 1. The data is indicating that the titania is significantly changing the properties of hydrogel. The titania becomes the part of chain as well as improves the mechanical movements of PAM chain. Table 1. Physical properties of hydrogels Sample
PAM
TiO2/PAM
Swelling behavior (%)
140
207
Adsorption capacity (%)
192
246
Bulk density (g/cm3)
0.64
0.59
Porosity(%)
79.08
85.34
3.2 FTIR studies Fig. 1 is showing spectra of PAM and TiO2/AM hydrogels. The observed peaks in the spectra are listed in Table 2.In the case of composite hydrogel, the characteristic peaks including N–H and C–O peaks of AAM are shifted towards
532
Barak et al. / Materials Today: Proceedings 12 (2019) 529–535
lower frequency (i.e. a blue shift), which is indicating some interaction/association between TiO2 and AM chain. The interaction may improves the stability of PAM .
0.40 0.35
AAM AAM-TiO2
0.30
Transmittance
0.25 0.20 0.15 0.10 0.05 0.00 -0.05 -0.10 4000
3500
3000
2500
2000
1500
1000
500
-1
Wave No. (cm ) Fig. 1 FTIR spectra of hydrogels Table 2 IR peaks of hydrogels [10,13] -1
Observed (cm ) 2936 2864 2349
Reported (cm-1) 2937 2870 2340
Inferences CH2 (asymmetric) CH2 (symmetric) n-CH stretching
1750 1261 1046
1740 1310 1096
C=O stretching N–H in-plane bending 1096 cm−1 C–O single bond
3.3 X-ray diffraction The XRD pattern of pure acrylamide is shown in Fig 2A, which is indicating a broad peak around 27° with an intensity of 751 ascribed to pure acryl amide hydrogel [14]. However, XRD pattern of TiO2/PAM is shown in Fig 2 B. The spectra is indicating a broad peak identical to PAM at two theta value of 25° along with the peaks at 46 and 54 due to the presence of TiO2 in prepared hydrogel. The preponing of peak of acrylamide by 20 is also revealing the expansion of matrix after incorporating the TiO2 in acrylamide hydrogel. The intensity of peak in both hydrogel also changed, which are indicating the change in crystallinity of acrylamide matrix.
Barak et al. / Materials Today: Proceedings 12 (2019) 529–535
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800 700
PAM TiO2/PAM
Intensity (a.u.)
600 500 400 300 200 100 5
10
15
20
25
30
35
40
45
50
55
60
Angle (2) Fig. 2 XRD patterns for PAM and TiO2/PAAM 3.4 Morphological analysis SEM micrograph of hydro-gels is given in Fig. 3. The SEM photograph (Fig. 3A) of PAM is showing regular morphology with layered structure and dense packing. Furthermore, the SEM images of TiO2/PAM are shown in Figure 3B is indicating the porous morphology with heterogeneous appearance. The comparison of these two images reveals that the TiO2 grains appear on the surface and the inside of the AAM. 3.5 Removal of methyl orange Fig 4 is showing UV spectra of methyl orange recoded after different after different time intervals. The regular decrease in intensity is revealing the removal of methyl orange from solution. The intensity of peaks was used to estimate the quantitative presence of methyl orange in dyes using Beers law. The lowering in intensity is indicating the efficient removal of methyl orange in 50 minutes is 95.6 %. The dye removal capacity of hydrogel was also calculated by earlier reported method [15] and values were found 391 mg/gm. The dye removal capacity of pure PAM hydrogel was also estimated by similar method and results are indicating 92.6 % improvements in dyes removal capacity of hydrogel. It may be because the presence of TiO2 produces the photo-catalytic properties in TiO2/PAM hydrogel along with large swelling capacity. The photocatalytic behavior supports to remove methyl orange, while swelling behavior improves the interaction time and sites of dyes on hydrogel. In totality the synergistic approach helps to design a better water purifying substrate.
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Barak et al. / Materials Today: Proceedings 12 (2019) 529–535
Fig. 3 SEM image of A) PAM and B) TiO2/PAM-TiO2 1.1 1.0 0.9
0.0 min 10.0 min 20.0 min 30.0 min 40.0 min 50.0 min
0.8
Absorbance
0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 -0.1
410 420 430 440 450 460 470 480 490 500 510 520 530 540 550 560 570 580 590 600
Wavelength (nm)
Fig. 4 UV spectra of methyl orange at different time interval
Barak et al. / Materials Today: Proceedings 12 (2019) 529–535
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4. Conclusion TiO2/Polyacrylamide hydrogel were synthesized and explored for efficient removal of methyl orange from artificial solutions. The increment in dyes removal capacity was explained on the basis of optimized physical properties of hydro gel due to addition of TiO2. Finally, study indicates the improvement in mechanical properties like swelling of hydrogel after addition of metal oxide along with photo-catalytic character. Acknowledgement The authors are thankful to Dr. Balaram Pani, Principal, BCAS, for maintaining socio-academic environment in the college and Director, USIC, University of Delhi for providing instrumentation facility. References 1. I. Ali, Chem. Rev.112(2012)5073–5091. 2. N. Pandey, S.K.Shukla, .N.B. Singh, Nanocomposite 3(2017)47-66 3.A. Ojstrsek, D. Fakin, Desalin. Water Treat. 33(2011)147-155. 4. A. Mittal, J. Mittal, A. Malviya, D. Kaur, V.K. Gupta, J. Colloid. Interf. Sci.,343 (2010)463–473. 5. A. Gil, F. Assis, C.C.Albeniz, S.A. Korili, Chem. Eng. J. 168(2011)1032-1040. 6. M. A. Shannon, P. W. Bohn, M. Elimelech, J. G. Georgiadis, B. J. Marinas, A. M. Mayes, Nature, 452(2008)301-310. 7. M.G. Buonomenna, Desalination, 14(2013)73–88. 8. Y.T.Zhou, H.L. Nie, C.B. White, Z.Y. He, L.M. Zhu, J. Colloid. Interf. Sci., 330(2009) 29–37. 9. O.Ozay, S. Ekici, Y. Baran, S. Kubilay, N. Aktas, N. Sahiner, Desalination, 260(2010) 57–64. 10. N.Pandey, S. Surana, S.K. Shukla, N.B. Singh Emerging Materials Research,6(2) (2017)1-9. 11. S.K. Shukla, S. R. Deshpande, S. K. Shukla, A. Tiwari, Talanta, 99(2012)283-287. 12. A.Tiwari, S.K. Shukla, Express Polymer Letters 3(9) (2009)553–559. 13. Y.M. Murali, P.S.K. Murthy, J. Sreeramulu, K.R. Mohana, J. Appl.Polym. Sci. 98(2005) 98,302. 14. P.S.K. Murthy,.Y.M. Murali, J. Sreeramulu, K.R. Mohana, React. Funct. Polym. 66(2006)1482. 15. R.P.Rastogi, N.B. Singh, S.K. Shukla, Ind. J. Eng. Mater. Sci. 18( 2011)390-392.
ScienceDirect Materials Today: Proceedings 12 (2019) 529–535
www.materialstoday.com/proceedings
NCMD 2018
Removal of methyl orange over TiO2/polyacrylamide hydrogel Anil Barak, Yash Goel, Raj Kumar and S.K. Shukla* Department of Polymer Science, Bhaskaracharya College of Applied Sciences, University of Delhi, Delhi-110075, India
Abstract The present work describes the preparation of titanium oxide impregnated polyacrylamide hydrogel (TiO2/PAM) by in-situ polymerization technique. The prepared hydrogel was characterized by fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and x-ray diffraction (XRD) techniques. The physical properties (solvent content, swelling behaviour, porosity) of hydrogel were also studied by ASTM method. Further, results are revealing the formation of composite hydrogel with improved properties. Thus, obtained prepared hydrogel was used for removal of methyl orange dye from laboratory prepared water samples. The methyl orange removal efficiency and kinetics was evaluated by UV-Visible spectroscopy in different conditions. The results indicate the improvement in dye removal capacity due to impregnation of metal oxides in hydrogel matrix. © 2019 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of National Conference on Materials and Devices (NCMD - 2018)
Keywords: Hydrogel, Physical properties, Methyl orange removal, Water purification
1. Introduction The use synthetic dyes in different industries such as paints, textiles, printing inks, pharmaceuticals, food, cosmetics, plastic, photographic and paper industries are increasing exponentially. It is estimated that ~ 7 × 105 tons of synthetic dyes and pigments are annually used in industries across the world [1-2]. Out of total use of dyes, about 40,000–50,000 tons of dyes are discharged in water bodies from natural or anthropogenic means. The increase of dyes contents are creating several problems like interference in penetration of sun rays in water bodies, increasing harmful chemicals and disturbing oxygen balance [3-4]. The photodegradtion of dyes in water bodies also produces several harmful chemicals with carcinogenic nature [5]. These secondary pollutants are consumed by aquatic organisms, which are further bio magnified and leads serious problems along with theft to several aquatic organism. *
Corresponding author: Tel. 091-11-25087595; Email: [email protected]
2214-7853 © 2019 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of National Conference on Materials and Devices (NCMD - 2018)
530
Barak et al. / Materials Today: Proceedings 12 (2019) 529–535
Thus, it is important to design a appropriate methods to remove and control the dyes from water bodies. Some important methods used for removal of dyes are adsorption, photo- oxidation, chemical precipitation, reverse osmosis and electro decomposition. However, the efficacy of all the methods are depends on available water purifying materials like adsorbents, membrane, photo-catalysts and hydrogel [6-7]. Further, hydrogel are water insoluble, cross linked, three-dimensional polymers with huge capacity of holding water their chain networks. It is because the presence of hydrophilic functional groups in the polymer backbone along with cross-links between network chains. In this regards several bio and petro polymers cellulose, alginate, chitosan and acrylamides are used for preparing hydro gel. Among the different hydrogel the acrylamides (AAM) based hydrogels are found of considerable interest in water purification due to their high mechanical strength, adsorption capacities, regeneration abilities and capability of being reused for continuous processes. The addition of metal oxides in hydrogel has been offers several advantageous properties like strength, adsorption sites and photo catalysis. Several metal oxides in incorporated hydro gel are used for water purifications for different pollutants [8-9]. However, the potential of material is indicating more intensive application for properties and applications [10]. In this context, the present study reveals the synthesis of zinc and titanium oxide incorporated poly-acrylamide hydrogel and its application in removal methyl orange from artificial water sample. The structure and properties of hydro gel are also discussed along with its mechanism of dye removal. 2. Experimental 2.1. Chemicals Acrylamide (AM) as monomer (99.5% ), Potassium peroxy disulfate (99.5%) as initiator, N,Nmethylenebisacrylamide (NMBA) as cross linker from E- Merk and Titanium Oxide (99.8%) from LOBA chemical were procured and used as such. AR grade solvents and double distilled water were used during entire investigation. 2.2 Synthesis of hydrogel In a typical experiment, 2g of acrylamide was polymerized in 20 ml distilled water using 200mg K2S2O8 along with 150 mg TiO2 after stirring on a magnetic stirrer for 1 hour at 50oC. After 30 minutes 50 mg cross-linker was also added. The stirring was continued for another 20 minutes, which yields a white precipitate of TiO2 incorporated polyacrylamide hydrogel. The solution was filtered and gel was transferred to a petridish, which was dried in a vacuum oven and stored for further characterization and applications. 2.3 Characterization 2.3.1 Physical Characterization Water adsorption, swelling index, porosity and bulk density of hydrogel was evaluated by standards ASTM methods. Initially the hydrogels were cut into pieces of 0·5 cm3 size by using a surgical blade. The samples were immersed in 100 ml distilled water at room temperature for 24 hours to reach swelling equilibrium, which resulted in the adsorption of water inside the network of hydrogels, and then the weight was taken. The samples were dried in a vacuum oven to remove interstitial water at 40°C and 4 mm mercury (Hg) pressure for 48 h and the weight was measured. The change in the thickness of hydrogel samples was measured with a digital Vernier calliper [11]. The calculation for water uptake was made using Eqn 1 and swelling behaviour by Eqn 2:
m(%)
m2 m1 100 (1) m1
where m1 is the mass of the dry specimen and m2 is the mass of the specimen after water adsorption.
T (%)
h2 h1 100 (2) h1
where h1 is the thickness (mm) of the dry hydrogel specimen and h2 is the thickness (mm) of the hydrogel after water immersion. Porosity is the measurement of void space in a material in which air or solvent can be introduced
Barak et al. / Materials Today: Proceedings 12 (2019) 529–535
531
and it is determined as the volume of water incorporated in the cavities per unit membrane volume using water uptake data discussed above. The calculation was made by Eqn 3:
Porosity
Wetweight Dryweight (3) Area length densityofwater
Further, bulk density of the hydrogel was determined by measuring the dimensions and weights of five samples. The size was measured with the help of a Vernier calliper. Three samples were tested for each experiment, and the average density was reported. 2.3.2. Structural characterization The chemical structure of hydrogel was evaluated by Bruker: Alpha model fourier transform infrared spectrometer. The spectra were recorded in the potassium bromide (KBr) phase after 16 scans at resolution of 4 cm−1 in the range of 4000–500 cm−1. The particle phase and crystallinity was estimated with the help of a Rigaku Rotaflex, Rad/Max-200B powder X-ray diffractometer using Cu Kα radiation with λ =1·5405 Å at a scanning rate of 2°/min. However, surface morphology of the synthesised materials was examined through a Hitachi-3700 scanning electron microscope operating at 20 kV. The samples were sputter-coated with a thin layer of gold before taking photographs to avoid charge accumulation. 2.3.3 Removal of dye The dyes removal capacity of hydrgel was estimated after recording the UV spectra of dyes solutions on a JASLO V-670 Spectrophotometer. Initially, aqueous solution of methyl orange was prepared by dissolving dye in requisite amount of water. Further, the 4 mL of solution was then taken in 3 different test tubes A, B and C. In tube A was left as reference while in B and C 200 mg of hydrogel piece was added. The sample B was kept in identical condition of A i.e ambient condition. However, test tube C was kept under the exposure of UV radiation in UV chamber. After the time interval of the 90 minutes (fig 2) solution was pipette out and UV-visible spectra were recorded in the wavelength range of 180-800 nm. 3. Results and discussion 3.1 Preparation of hydrogel The change in colour sequence and precipitation is indicative for the formation of impregnated hydrogels in the presence of TiO2 by free radical polymerisation [12]. The physical parameters of hydro gel are given in Table 1. The data is indicating that the titania is significantly changing the properties of hydrogel. The titania becomes the part of chain as well as improves the mechanical movements of PAM chain. Table 1. Physical properties of hydrogels Sample
PAM
TiO2/PAM
Swelling behavior (%)
140
207
Adsorption capacity (%)
192
246
Bulk density (g/cm3)
0.64
0.59
Porosity(%)
79.08
85.34
3.2 FTIR studies Fig. 1 is showing spectra of PAM and TiO2/AM hydrogels. The observed peaks in the spectra are listed in Table 2.In the case of composite hydrogel, the characteristic peaks including N–H and C–O peaks of AAM are shifted towards
532
Barak et al. / Materials Today: Proceedings 12 (2019) 529–535
lower frequency (i.e. a blue shift), which is indicating some interaction/association between TiO2 and AM chain. The interaction may improves the stability of PAM .
0.40 0.35
AAM AAM-TiO2
0.30
Transmittance
0.25 0.20 0.15 0.10 0.05 0.00 -0.05 -0.10 4000
3500
3000
2500
2000
1500
1000
500
-1
Wave No. (cm ) Fig. 1 FTIR spectra of hydrogels Table 2 IR peaks of hydrogels [10,13] -1
Observed (cm ) 2936 2864 2349
Reported (cm-1) 2937 2870 2340
Inferences CH2 (asymmetric) CH2 (symmetric) n-CH stretching
1750 1261 1046
1740 1310 1096
C=O stretching N–H in-plane bending 1096 cm−1 C–O single bond
3.3 X-ray diffraction The XRD pattern of pure acrylamide is shown in Fig 2A, which is indicating a broad peak around 27° with an intensity of 751 ascribed to pure acryl amide hydrogel [14]. However, XRD pattern of TiO2/PAM is shown in Fig 2 B. The spectra is indicating a broad peak identical to PAM at two theta value of 25° along with the peaks at 46 and 54 due to the presence of TiO2 in prepared hydrogel. The preponing of peak of acrylamide by 20 is also revealing the expansion of matrix after incorporating the TiO2 in acrylamide hydrogel. The intensity of peak in both hydrogel also changed, which are indicating the change in crystallinity of acrylamide matrix.
Barak et al. / Materials Today: Proceedings 12 (2019) 529–535
533
800 700
PAM TiO2/PAM
Intensity (a.u.)
600 500 400 300 200 100 5
10
15
20
25
30
35
40
45
50
55
60
Angle (2) Fig. 2 XRD patterns for PAM and TiO2/PAAM 3.4 Morphological analysis SEM micrograph of hydro-gels is given in Fig. 3. The SEM photograph (Fig. 3A) of PAM is showing regular morphology with layered structure and dense packing. Furthermore, the SEM images of TiO2/PAM are shown in Figure 3B is indicating the porous morphology with heterogeneous appearance. The comparison of these two images reveals that the TiO2 grains appear on the surface and the inside of the AAM. 3.5 Removal of methyl orange Fig 4 is showing UV spectra of methyl orange recoded after different after different time intervals. The regular decrease in intensity is revealing the removal of methyl orange from solution. The intensity of peaks was used to estimate the quantitative presence of methyl orange in dyes using Beers law. The lowering in intensity is indicating the efficient removal of methyl orange in 50 minutes is 95.6 %. The dye removal capacity of hydrogel was also calculated by earlier reported method [15] and values were found 391 mg/gm. The dye removal capacity of pure PAM hydrogel was also estimated by similar method and results are indicating 92.6 % improvements in dyes removal capacity of hydrogel. It may be because the presence of TiO2 produces the photo-catalytic properties in TiO2/PAM hydrogel along with large swelling capacity. The photocatalytic behavior supports to remove methyl orange, while swelling behavior improves the interaction time and sites of dyes on hydrogel. In totality the synergistic approach helps to design a better water purifying substrate.
534
Barak et al. / Materials Today: Proceedings 12 (2019) 529–535
Fig. 3 SEM image of A) PAM and B) TiO2/PAM-TiO2 1.1 1.0 0.9
0.0 min 10.0 min 20.0 min 30.0 min 40.0 min 50.0 min
0.8
Absorbance
0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 -0.1
410 420 430 440 450 460 470 480 490 500 510 520 530 540 550 560 570 580 590 600
Wavelength (nm)
Fig. 4 UV spectra of methyl orange at different time interval
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4. Conclusion TiO2/Polyacrylamide hydrogel were synthesized and explored for efficient removal of methyl orange from artificial solutions. The increment in dyes removal capacity was explained on the basis of optimized physical properties of hydro gel due to addition of TiO2. Finally, study indicates the improvement in mechanical properties like swelling of hydrogel after addition of metal oxide along with photo-catalytic character. Acknowledgement The authors are thankful to Dr. Balaram Pani, Principal, BCAS, for maintaining socio-academic environment in the college and Director, USIC, University of Delhi for providing instrumentation facility. References 1. I. Ali, Chem. Rev.112(2012)5073–5091. 2. N. Pandey, S.K.Shukla, .N.B. Singh, Nanocomposite 3(2017)47-66 3.A. Ojstrsek, D. Fakin, Desalin. Water Treat. 33(2011)147-155. 4. A. Mittal, J. Mittal, A. Malviya, D. Kaur, V.K. Gupta, J. Colloid. Interf. Sci.,343 (2010)463–473. 5. A. Gil, F. Assis, C.C.Albeniz, S.A. Korili, Chem. Eng. J. 168(2011)1032-1040. 6. M. A. Shannon, P. W. Bohn, M. Elimelech, J. G. Georgiadis, B. J. Marinas, A. M. Mayes, Nature, 452(2008)301-310. 7. M.G. Buonomenna, Desalination, 14(2013)73–88. 8. Y.T.Zhou, H.L. Nie, C.B. White, Z.Y. He, L.M. Zhu, J. Colloid. Interf. Sci., 330(2009) 29–37. 9. O.Ozay, S. Ekici, Y. Baran, S. Kubilay, N. Aktas, N. Sahiner, Desalination, 260(2010) 57–64. 10. N.Pandey, S. Surana, S.K. Shukla, N.B. Singh Emerging Materials Research,6(2) (2017)1-9. 11. S.K. Shukla, S. R. Deshpande, S. K. Shukla, A. Tiwari, Talanta, 99(2012)283-287. 12. A.Tiwari, S.K. Shukla, Express Polymer Letters 3(9) (2009)553–559. 13. Y.M. Murali, P.S.K. Murthy, J. Sreeramulu, K.R. Mohana, J. Appl.Polym. Sci. 98(2005) 98,302. 14. P.S.K. Murthy,.Y.M. Murali, J. Sreeramulu, K.R. Mohana, React. Funct. Polym. 66(2006)1482. 15. R.P.Rastogi, N.B. Singh, S.K. Shukla, Ind. J. Eng. Mater. Sci. 18( 2011)390-392.