Available online at www.ijntps.org | ISSN: 2277 – 2782 INTERNATIONAL JOURNAL OF NOVEL TRENDS IN PHARMACEUTICAL SCIENCES
RESEARCH ARTICLE
Effective Adsorption of Chromium using Chitosan/ Sodium Alginate/Polyethylene glycol ternary blends 1
2
2
2*
A. Srividhya, M. Saranya, T. Gomathi and P.N. Sudha
1
Department of Chemistry, Dravidian University, Kuppam, Andhra Pradesh, India *Department of Chemistry, D.K.M. College for Women, Vellore, Tamil Nadu, India
2
Abstract The ternary blends consisting of chitosan (CS)/Sodium alginate(SA)/Polyethylene glycol(PEG) were preapared by solution blending method. Chitosan was studied as a potential biosorbent due to its positive charge and relatively low cost. Sodium Alginate features are formability, hydrophilicity, biocompatibility, biodegradability, and exhibits high activity with the carbonyl and hydrogen groups on the chain. Polyethylene glycol (PEG), a linear or branched polyether, is formed through ring-opening polymerization of ethylene oxide. Blends of synthetic and natural polymers represent a new class of materials and have attracted much attention, especially in bio-application as biomaterial. The study involves evaluating the metal binding performance of chitosan/sodium alginate/polyethylene glycol using chromium aqueous solution. The characterization of the prepared sample was carried out using analytic techniques. The Intermolucular interactions were determined by Fourier Transform infrared and Crystalline nature of the prepared ternary blend determined by X-ray Diffraction studies. Thermal studies were carried out using TGA and DSC. Morphology of the Chitosan/ Sodium Alginate/ Polyethylene glycol ternary blends were observed using SEM studies. The blend shows significant effect on Adsorption models. Keywords: Blends, Adsorption, Chromium, Chitosan, Polyethylene glycol, Sodium Alginate. INTRODUCTION The contamination of water from the disposal of industrial waste often contain considerable amount of heavy metals that would endanger public health and environment if not given adequate treatment. Heavy metals such as Hg, Cr, Ni, Cd, Cu and Zn, which are usually associated with greater degree of toxicity are present in wastewater. Chromium is one such toxic metal which is being widely used. Chromium is generated by electroplating, tanning and textile industry and is potentially toxic to humans [1]. Different technologies and processes are currently used such as ion-exchange, activated charcoal, complexation, precipitation and other chemical and electrochemical techniques. Adsorption is widely recognized as an effective, efficient and economic method for water contamination applications, and for separation analytical purposes. Biosorption, which involves active and non-active uptake by biomass, is a good alternative to traditional processes. Widely available biopolymers are also being used for sorption mainly because they are a cheap resource. Chitosan, consists of a biopolymer of glucosamine and NVOLUME 7 | NUMBER 1 | FEB | 2017
acetylglucosamine units linked by β-1,4 glycosidic bonds. Today, chitosan is mostly prepared commercially by the alkaline deacetylation of chitin. Chitin, composed of β (1→4)-N-acetyl-Dglucosamine units, is synthesized by a number of living organisms in the lower plant and animal kingdoms, serving many functions where reinforcement and strength are required [2]. Alginates derived from seaweed (Phaeophyceae, mainly Laminaria) possess good film-forming properties that make them particularly useful in food packaging applications. They are linear unbranched polymers containing β-(1->4)-linked Dmannuronic acid and α-(1->4)-linked L-guluronic acid residues. Alginate gels are not thermo reversible.[3] Polyethylene glycol is non-toxic, odorless, neutral, lubricating, nonvolatile and nonirritating and is used in a variety of pharmaceuticals and in medications as a solven, To whom correspondence should be addressed:
P.N. Sudha Email:
[email protected]
|8
P.N.Sudha et al., Effective Adsorption of Chromium using Chitosan/ Sodium Alginate/Poly Ethylene Glycol ternary blends dispensing agent, ointment and suppository bases, vehicle, and tablet excipient, this polymer is chosen for its unique properties. Blend polymers are used often in industry to enhance the mechanical properties. To increase the strength of a blend polymer, a homogeneous mixture must be obtained. There are three ways in which to mix polymers: (I) Physical blend involving large particles, (II) Physical blend involving fine particles using a mold and (III) Mixing polymers using a chemical known as a compatibilizer [4]. The objective of the work is to develop a cost effective technology for the removal of heavy metals and prepare a novel biosorbent (chitosan/sodium alginate/polyethylene glycol) which is suitable for adsorption of high percentage of heavy metals. MATERIALS AND METHODS MATERIALS Chitosan of 92% deacetylated was purchased from India Sea Foods, Cochin, Kerala. Sodium alginate and polyethylene glycol were purchased from Sigma Aldrich, Banglore, India. All other chemical used were of analytical grade and used as received. Preparation of Chitosan/ polyethylene glycol/ sodium alginate ternary blends One gram of chitosan was dissolved in 100 ml of 10% acetic acid by stirring for 20 minutes and the viscous liquid was used for further reaction. 1 gram of polyethylene glycol (400) was dissolved in 20ml of deionised water. 1 gram of sodium alginate was made a paste with 25 ml of deionised water with continuous stirring. All the three solutions were stirred well continouslu for 30 minutes and poured in petriplate and dried. Characterization Fourier transform infrared spectroscopy FT-IR was used to characterize the blends. FT-IR spectra were obtained in the wavenumber range 1 -1 from 4000 to 650 cm- during 64 scans, with 2 cm resolution (Paragon 1000, Perkin-Elmer, USA). The FT-IR spectra were normalized and major vibration bands were identified associated with the main chemical groups. X-ray diffraction X-ray diffractometer was used to characterize the crystallinity of pure and the blend films. Xray diffraction (XRD) patterns were recorded by VOLUME 7 | NUMBER 1 | FEB | 2017
reflection method with nickel-filtered Cu Kα radiation using a RigakuX-ray diffractometer operated at 40kV and 30mA in the 2θ scanning mode from 5° to 80°. Thermogravimetric Analysis Thermogravimetric analysis was conducted on a SDT Q600 V8.0 Build 95 instrument in the o o temperature range of 50 to 800 C and the heating rate of 20 K/min. Differential Scanning Calorimetry The differential scanning calorimetry (DSC) measurements were performed with NETZSCH DSC 200 PC in a pan Al, pierced lid in the N2 atmosphere at a heating rate of 20 K /min. Scanning electron microscopy (SEM) The morphology of the films obtained was assessed by scanning electron microscopy (SEM), (JSM 6360LV, JEOL/Noran), the microscope was attached to a dispersive energy spectrometer (EDS). The images were obtained using an accelerating voltage of 10– 15 kV. Before examination the samples were sprayed with a fine layer of gold using a low deposition rate, refrigerated and placed at the maximum distance from the target to prevent damage to them. Adsorption studies of heavy metal Chromium using CS/SA/PEG ternary blends. The metal solutions with different initial concentrations were agitated and the solution was taken from the bottle to analyse the amount of unadsorbed metals at equilibrium remediation as per the methods of APHA (1990) by Atomic Absorption Spectroscopy (Varian AAA 220 FS). RESULT AND DISCUSSION FT-IR Spectral studies (FTIR) The FT-IR Spectra of Chitosan (Figure – 1) shows -1 the broad band at 3454.75 cm for –OH stretching, which overlaps the NH stretching in the same region and the presence of intra molecular hydrogen bonding. The peak observed at 2923.08 -1 cm is typical C-H stretch. A small peak at 1740.23 -1 cm is due to C=O stretching. The absorption in the -1 -1 range of 1628.87 cm to 1540.02 cm represents the amide I carbonyl stretch as the shoulder on the broad amine deformation [5] and the peak at -1 shows the presence of CH2 1421.52 cm deformations and OH deformation [6]. The peak at
|9
P.N.Sudha et al., Effective Adsorption of Chromium using Chitosan/ Sodium Alginate/Poly Ethylene Glycol ternary blends -1
-1
the blended polymer is not very stable. Eighty percent of the blends add disintegrated within 0 460 C. At the end of the experiment at around, only of the blend remained as a residue. From 500°C there is only a linear shallow decrease in weight with increase in temperature.
1384.01 cm , 1322.23 cm shows the presence of C-O stretching and O-H in plane bending vibration. -1 -1 The peaks at 1098.72cm and 1021.37cm show the presence of C-N stretching coupled vibrations, glycosidic bonds in the pyranose ring. The peaks at -1 -1 -1 776.38 cm , 674.35 cm and 472.23 cm shows the presence of CH2 rocking, OH out of plane bending and C-C bending .[7] The FT-IR Spectra of CS/AL/PEG Blend (1:1:1) (Figure – 2) represents CS/SA/PEG(1:1:1) ternary blends which shows the -1 -1 prominent peaks at 3415.9 cm 1604.7cm , -1 -1 1409.6cm and 1091.6 cm . The broad peak at -1 -1 3415.9 cm 1, 1604.7 cm , 1409.6cm and 1091.6 -1 -1 cm . The broad peak at 3415.9 cm shows the presence of inter molecular hydrogen bonding OH stretching, NH stretching and also the polymeric -1 association. The peak at 1604.7cm shows the presence of N-H bending (amide II band) which confirms the polymeric linkage. The peaks at 1409.6 -1 -1 cm and 1091.6 cm shows the presence of OH in plane bending and C-O stretching vibrations. The change in shift of the observed peak proves that blending has done effectively.
DSC studies Figure (5) represents the DSC curves of the CS/ SA / PEG (1:1:1) ratio. The glass transition temperature of the blend was observed at 78.35°C. A broad endothermic peak obtained at around 230°C shows the recrystallisation process at different temperature. This shows significant effect of high thermal stability. Scanning Electron Microscopic (SEM) The CS/SA/PEG (1:1:1) blend was subjected to Scanning Electron Microscopic analysis viewing both the surface and cross section. The results are presented in fig 6 &7. Film morphology was determined from SEM micrographs of film surface and cross-section. The surface morphology of the blend film contained round and other shaped particles immersed in homogenous chitosan matrix indicating that the three components existed in the blend in a fine mixture (Figure –6). The cross-section of the blend films was rough. In addition, nanopores were also observed throughout the film matrices (Figure - 7), which suggested that the blend films contained nanoporous structures. The nanopores in CS/SA/PEG films were formed due to selfcondensation and phase separation of the polymers which helped it to be used as a good adsorbent [9].
X ray Diffraction studies (XRD) The (Figure -3) shows the XRD spectrum of CS/SA/PEG (1:1:1) ternary blends shows a very broad peaks at around 2θ=20° and 2θ=42°. From the nature of broad peak, it was concluded that the CS/SA/PEG has amorphous nature. The crystallinity of prepared ternary blend is a key-parameter in the accessibility to internal sites for both metal ions and water [8]. TGA studies TGA thermogram details of CS/SA/PEG (1:1:1) ternary blends. From the (Figure-4) it is evident that Fig 1. FTIR Spectral details of Chitosan
Fig 2. FTIR Spectral details of CS/SA/PEG Blend(1:1:1) 100.0
90 D7 88
95
86
90
84
85
82
80
64 62
3938.0 1604.7
70
674.35
60
1151.84 1098.72 1021.37
1409.6
75 3928.6
65
1091.6
3912.8 3826.3 3811.8 3740.4
55 50 %T
3776.4 3791.4
2337.1 2352.7
45 40
3454.75
68
1421.52 1384.01 1322.23
70 1628.87
%T
72
1540.02
2923.08
74
1740.23
76
776.38
78
66
3897.2
472.23
80
35 30
60
25
58
20
56
15
54
10
2922.7
5
52 50
3415.9
0.0
3500
3000
2500
2000
Wavenumbers (cm-1)
VOLUME 7 | NUMBER 1 | FEB | 2017
1500
1000
500
4000.0
3600
3200
2800
2400
2000
1800
1600
1400
1200
1000
800
600
400.0
cm-1
|10
P.N.Sudha et al., Effective Adsorption of Chromium using Chitosan/ Sodium Alginate/Poly Ethylene Glycol ternary blends
200
Fig 4. TGA thermal studies of CS/SA/PEG Blend (1:1:1)
69.8951 74.3325
300
49.0492
Lin(counts)
400
54.9065 59.4031 62.3614
24.1405 27.4538 31.0234
500
37.4527 41.7521 42.6199
20.3145
Fig 3. X ray Diffraction studies of CS/SA/PEG Blend (1:1:1)
100
0 0
10
20
30
40
50
60
70
80
90
2Theta
Fig 5. DSC thermal studies of CS/SA/PEG Blend (1:1:1)
Fig 6. Scanning Electron Micrograph of CS/SA/PEG blend (1:1:1) – Surface Morphology
Fig 7. Scanning Electron Micrograph of CS/SA/PEG blend (1:1:1) – Cross Sectional Morphology
Fig 8. Langmuir isotherm for Chromium
Chromium
Ceq/Cads (g/dm3)
2.5 2.0 1.5 1.0 0.5 0.0 0
100
200
300
3
Ceq (mg/dm )
VOLUME 7 | NUMBER 1 | FEB | 2017
|11
P.N.Sudha et al., Effective Adsorption of Chromium using Chitosan/ Sodium Alginate/Poly Ethylene Glycol ternary blends ADSORPTION STUDIES OF CHROMIUM WITH CS/PEG/AL (1:1:1) In this study, chitosan/sodium alginate/ polyethylene glycol blend were developed and used as a biosorbent for the removal of Chromium (VI) ions from aqueous solution.. Langmuir Isotherm The Langmuir adsorption is one of the most widely used isotherm for monolayer adsorption on to the adsorbent which is made up of elementary sites. The linearized Langmuir isotherm equation is as follows: Ceq /Cads = bCeq /KL + 1/KL Cmax = KL /b
where Cads = amount of metal ion adsorbed (mg/g) Ceq = equilibrium concentration of metal ion (mg −3 dm ) 3 KL = Langmuir constant (dm /g) 3 b = Langmuir constant (dm /mg) Cmax = maximum metal ion adsorbed The constants “b” and “KL” can be attained by Langmuir equation.[10]. The Langmuir adsorption isotherm plot for Cr(VI) using CS/SA/PEG blends. A plot of Ceq/Cads vs. Ceq yield a straight line (Figure-8), where “b” and “KL” can be calculated using the intercept and slope of linear plot and also verifying the use of the Langmuir adsorption isotherm.
Table 1. Comparison of Langmuir and Freundlich adsorption isotherm parameters Metal ions Langmuir constants 3 3 2 KL (dm /g) b (dm /mg) Cmax (mg/g) R Cr(VI) 1.015 0.003332 304.62 0.9253 Table 1 shows that the Langmuir model fitted the experimental data well. This does not necessarily mean that the hypothesis of the model is valid for these sorption systems is verified. The parameters of Langmuir adsorption isotherm, evaluated from the linear plots, are presented in Table - 1 along with the correlation 2 coefficient. The magnitude of the Langmuir constants and the correlation coefficient (R = 0.9253), indicate that the uptake of Cr(VI) from aqueous solutions by the CS/SA/PEG blend is feasible.. The obtained results of adsorption of Cr(VI) onto biosorbent relates with the Langmuir equation and also the degree of suitability was estimated by dimensionless constant separation factor or equilibrium parameter, RL which can be calculated from the equation for different initial concentrations of Cr(VI) RL = 1/1+bCf 3 Where Cf is the final concentration (mg/dm ) of Cr(VI) 3 b is the Langmuir constant (dm /mg) The above calculated RL values used to predict whether an adsorption system is favorable or unfavorable. If the obtained RL> 1, unfavorable isotherm; RL= 1, linear isotherm; RL= 0, irreversible isotherm; and 0 < RL< 1 favorable isotherm. The calculated RL values were represented in Table-2. Table 2. Calculated RL values 3 Metal ions Initial concentration C0 (mg/dm )
Final concentration Cf RL values 3 (mg/dm ) 1000 280 0.517341 500 105 0.740818 Cr(VI) ion 200 40 0.882394 100 19 0.940461 50 7.5 0.975619 From the above obtained values in (Table-2), it was evident that the calculated RL falls within the range of 0
