beneficial effect of chitosan gpolyacrylamide copolymer ... · state in india) is becoming a ......

INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCES Volume 1, No 5, 2011

© Copyright 2010 All rights reserved Integrated Publishing Association

Research article ISSN 0976 – 4402

Received on December, 2010 Published on January, 2011 820

Beneficial effect of chitosangpolyacrylamide copolymer in removal of heavy metals from industrial dye effluents

Z. Ansar Ali 1 , Jayachandran Venkatesan 2 , Se Kwon Kim 2, 3 , P.N. Sudha 4 1 Department of Chemistry, Bharathiar University, Coimbatore, Tamil nadu

2 Department of Chemistry, Pukyong National University, Busan, Republic of Korea 3Marine Bioprocess Research Center, Pukyong National University, Busan, Republic of

Korea 4Department of Chemistry, DKM College, Thiruvalluvar university, Vellore, Tamilnadu

[email protected]

ABSTRACT

Water is an essential matter to human and other living organisms. Chitin, chitosan, poly acrylamide polymers are individually used for waste water treatment due to biocompatibility and inexpensive. In the present study graft copolymer of chitosan with acrylamide has been synthesized in the presence of nitrogen using ceric ammonium nitrate, nitric acid redox system with UV irradiation. The synthesis copolymer subjected to various analytical techniques such as fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) to confirm the formation of copolymer. The cross linkage between chitosan and polyacrylamide was analysed and proven with FTIR and DSC. The SEM results shown the formation and strong chemical interaction between chitosan and polyacrylamide. The prepared graft copolymer was subjected to industrial dye effluent and result revealed that the copolymer prepared is excellent in removing all the polluted ions including heavy metals. Hence, chitosangpolyacrylamide copolymer could open way for waste water treatment in industrial level.

Keywords: Chitosan, polyacrylamide, copolymer, dye effluent treatment,

1. Introduction

Water is an essential matter to human and other living organism. Water is polluted in many ways like effluent of leather and chemical industries, electroplating industries and dye industries (Sudha, 2010). The scarcity of potable ground water in Tamil Nadu (one of the state in India) is becoming a serious issue due to industrial pollution. The high level of heavy metal ion concentrations were detected with antimony up to 0.42 mg/1, mercury to 0.02 mg/1, lead to 1.82 mg/1, and cadmium and 1.31 mg/1 and including microbial contamination (Somasundaram et al., 1993). Specifically, Ranipet has been known for air and water pollution caused by tanneries, chemical industries and dye industries. The effluent polluted ground water and turned it “brownish” causing several diseases to the residents. Several methods have been used to purify the water like sedimentation, filtration, ultra filtration, and reverse osmosis. Membrane filtration, widely used in chemical and biotechnology processes, is already established as a valuable means of filtering and cleaning wastewater and industrial process water and moreover membrane filter are highly efficient and inexpensive and more flexible to handle (Chang et al., 2002).

Chitosan belongs to a family of linear, cationic biopolymers obtained from Ndeacetylation of chitin in alkaline media. This polysaccharide is a random copolymer, containing (14)


Z. Ansar Ali, Jayachandran Venkatesan, Se Kwon Kim, P.N. Sudha International Journal of Environmental Sciences Volume 1 No.5, 2011

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linked 2acetamide2deoxy(3Dglucopyranose) and 2amino2deoxy(3Dglucopyranose) residues. Chitosan is watersoluble at an acidic pH and provide interesting properties such as biocompatibility, biodegradability and its degradation products are nontoxic directed to numerous applications in waste water treatment, chemical industry, pharmacy, biotechnology and biomedicine (Kim and Mendis, 2006; Kim and Rajapakse, 2005; Shahidi and Abuzaytoun, 2005; Venkatesan and Kim, 2010; Venkatesan et al., 2010). Chitin and chitosan are widely used for waste water treatment and treatments of polymers experimentally proven that decrease the chemical oxygen demand, total nitrogen and destroy the microbial population (Meyer et al., 2000; Sudha, 2010). However, due to its low mechanical strength and flexible behavior, chitosan has limited in application of water treatment, while addition of synthetic polymers increased its properties tremendously.

Chitosan bears two types of reactive groups, free aminogroups on deacetylated units and secondly, the hydroxyl groups on C3 and C6 carbons. These reactive groups are easily modified with other polymeric compound by copolymerization. Polyacrylamide is a polymer formed from acryl amide subunits that can also be readily crosslinked. In the crosslinked form, it is highly waterabsorbent and can be used for waste water treatment (Martin et al., 1996; Venkatesan and Kim, 2010; Venkatesan et al., 2010). Chitosan and polyacryl amide are highly promising biomaterials for various field. Microspheres of polyacrylamide – grafted chitosan crosslinked with glutaraldehyde was by grafting of acrylamide onto a chitosan backbone at three acrylamide concentrations (polymer/monomer ratio = 1:1, 1:2, and 1:3). The synthesis of the grafted polymer was achieved by K2S2O8induced freeradical polymerization (Kumbar et al., 2003).Various researchers have developed many methods for copolymerization of chitosan with acryl amide such as microwave assisted (ceric ammonium sulphate drug delivery).

Graft polymerization of acrylamide on chitosan using ammonium persulfate as an initiator, was prepared (Mochalova et al., 2006). The effect of temperature pH of the medium and concentrations of initiator, chitosan and acrylamide on grafting kinetics and efficiency were established. Graft copolymerization of mixtures of acrylic acid and acrylamide onto chitosan using potassium per sulphate as initiator and methylenebisacrylamide as a crosslinker was carried (Mochalova et al., 2007). Vinyl graft copolymerization featuring recent advances toward controlled radicalbased reactions with Chitin/Chitosan trunk polymers was reported (Jenkins and Hudson, 2001). Semiinterpenetrating polymer network hydrogel was prepared to recognize hemoglobin, by molecularly imprinted method, in the mild aqueous media of chitosan and acrylamide in the presence of N,N‘methylenebisacrylamide as the crosslinking agent (Xia et al., 2005). Hydrogel was synthesized by crosslinking acrylamidechitosan mixture with N,N' methylene bisacrylamide (Makarand V. Risbud, 2000). Grafting of acrylamide onto carboxyl methyl chitosan using ceric ammonium nitrate as an initiator was carried out under nitrogen atmosphere in aqueous solution (Joshi and Sinha, 2007). The molecularly imprinted polymer was achieved by entrapment of the selective soft polyacrylamide gel in the pores of the crosslinked chitosan beads by letting acrylamide monomer and the protein diffuse into the pores of chitosan beads before starting the polymerization and was reported (Guo et al., 2004).

In the present study, we have synthesized copolymer of acrylamide and chitosan and with ceric ammonium nitrate as a redox system with UV radiation. The obtained copolymer was subjected to various analytical techniques such as FTIR, DSC and SEM to confirm the copolymer formation. From the results we have concluded that, the formation of copolymer of acryl amide on the chitosan matrix was in proper arrangement. This copolymerization will



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be highly useful for various application fields including drug delivery and waste water treatment. In the present work efficacy of chitosan grafted polyacrylamide for treating dye industry effluent was attempted and found successful.

2. Materials and Methods

Chitosan was kindly gifted by India Sea food, Cochin, Kerala, India. acrylamide, ceric ammonium nitrate and all other chemical used in the experiments were of analytical grade. The dye industry effluent was collected from the outlets of tanneries of SIPCOT industrial estate, Ranipet, Vellore district, Tamilnadu. India

2.1 Preparation of copolymer

A 2% W/V solution of chitosan was prepared in 2% aq. acetic acid. A solution of 0.1M ceric ammonium nitrate (CAN) in 10ml of in nitric acid was added followed by a known amount (1g in 50 ml of water) of acrylamide drop by drop with continuous stirring with UV. The temperature of reaction was maintained at 70 °C for 45 minutes, the product was precipitated by using sodium hydroxide solution with vigorous stirring. The precipitate was washed with distilled water several times to remove homopolymer formed and filtered.

The grafting yield (GY %) and grafting efficiency (GE %) was calculated as follows:

Wg Grafting Efficiency (GE %) = x 100

Wg + Wi

WgWi Grafting Yield (GY %) = ×100

Wi

Where, Wg Weight of grafted copolymer; Wi Weight of homopolymer (acryl amide), respectively

2.2 Characterization of polymer

The prepared grafted copolymer of chitosangpolyacrylamide was analysed by FTIR in a wide range wavelength between 400 cm 1 and 4000 cm 1 , and in solid state using KBr pelletisation. A Perkin – Elmer spectrophotometer was used. A DSC thermo gram was obtained by NET Z SCH – Geratebau GmbH thermal analyser. Samples were dried in vacuum desiccators and powdered in a standard aluminum pan. 2.0mg of this sample was heated about 33 °C to 350 °C at a heating rate of 10 °K/min under constant purging of nitrogen. SEM study of the prepared graft copolymer was carried out by JSM – 640 Scanning Electron Microscope, JEOL. The dried sample film was cut and was sputter – coated with gold using a microscope sputter coater and viewed through the microscope.

2.3 Physiochemical characterization of Effluent



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Physicochemical factors such as pH, Electrical conductivity (EC), Dissolved Oxygen (DO), Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Dissolved Solids (TDS), Total Suspended Solids (TSS), Total Solids (TS), Alkalinity, Chloride, Hardness, sodium and heavy metals such as cadmium, copper, cobalt, nickel, chromium, lead and zinc were analyzed as per the methods (Eaton and Franson, 2005; Trivedy and Goel, 1984)

3. Results and Discussions

3.1 General description

The prepared chitosangpolyacrylamide copolymer appeared as yellowish white solid, insoluble in water, and has less swelling capacity than unmodified chitosan. The scheme of the possible polymerization reaction has been described in Figure 1. It indicates the formation of free radical initially with acrylamide monomer which constantly gets added to chitosan residue.

Figure 1: Scheme of the possible reaction

3.2 Effect of time on copolymerization

The effect of reaction time on copolymer formation was studied by keeping the initiator concentration, monomer (fixed weight of chitosan and acrylamide 0.5 g) amount, and temperature (70 °C), constant. The yield of copolymer, grafting efficiency and grafting yield have been represented in Figure 2. The grafting efficiency of the copolymer the formation in reaction is not significant change, whereas, grafting yield is significantly changed with reaction time. As a result, the maximum yield has been found at 55 min. Hence 55 min was found to be rate of grafting (Joshi and Sinha, 2007; Sharma et al., 1980).



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Figure 2: Determination of grafting rate with time

3.3 Effect of initiator concentration

The reaction conditions were kept fixed, the effect of ceric ammonium nitrate concentration has been changed, and the changes in the grafting efficiency and grafting yield have been shown in Figure 3. The graft yield and grafting efficiency are increasing with the increase in initiator concentration. The maximum yield was found at initiator concentration 0.9 g/10ml of HNO3, hence 0.9 g was found to be the optimum initiator concentration in this grafting reaction at 70 ºC. This might be because of CAN directly attacks the characteristic group of alcohol and amine group of chitosan polymer backbone producing free radicals; those initiate the graft copolymerization with acrylamide. It was found at lower level of CAN concentration grafting yield is very low, comparatively grafting efficiently is moderate. Moreover, by increasing the initiator concentration, there might be increase in free radical formation randomly; hence the grafting yield increases significantly. Further increase the initiator concentration resulted in a decrease of the grafting efficiency and grafting. It might be due to increases in the number of chitosan free radicals terminated prior to acrylamide addition (Joshi and Sinha, 2007; Shukla and Sharma, 1987).

Figure 3: Effect of initiator concentration on copolymerization

3.4 Effect of monomer concentration

Figure 4, represents the effect of monomer concentration of acrylamide on copolymerization reaction (grafting parameters). The grafting efficiency and grafting yield was found to



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increase with increasing monomer (acrylamide) concentration. The maximum grafting yield has been found at 0.7 mol/l, and then decreased. This decreasing behavior might be because increasing the monomer concentration causes reduction in the active site backbone of chitosan polymer. Additionally, higher the monomer concentration, the primary radicals attack the monomer instead of reacting with the backbone polymer. The excess monomer concentration will shield the graft copolymer which might be inhibiting the rate of copolymerization. Hence 0.7 g of acrylamide was found to be the optimum monomer concentration in this grafting reaction at standard 70 °C (Joshi and Sinha, 2007).

Figure 4: Effect of monomer amount on copolymer formation

3.5 FTIR study of copolymer

FTIR is a promising tool to identify unknown substances and to determine the amount of components in a given sample. This test was performed to get authenticated information about the vibrational origin of the amide, carbonyl and alcoholic groups of chitosan and polyacrylamide. Copolymer based on polyacrylamide has been synthesized by grafting acrylamide onto chitosan molecule via, ceric ammonium nitrate with UV irradiation.

The grafting of copolymer was confirmed by FTIR spectroscopy and the spectrums of chitosan and chitosangpolyacrylamide graft copolymer are depicted in Figure 5 (a) (b), respectively. The IR spectrum of the chitosan has strong peaks observed at 3454.75 cm 1 due to OH group, bands at 2923.08 cm 1 and 1021.37 cm 1 may be due to CH stretching vibration of =CHOCH2 (COC) stretching vibration, respectively.

In the case copolymer of chitosangpolyacrylamide peaks are sharper than that of chitosan alone. The FTIR spectrum of chitosangpolyacrylamide copolymer showed a broad absorption band at 3434.71cm 1 due to–OH stretching of polyacrylamide and amide group of chitosan. A band at 1633.40 cm 1 and 1411.69 cm 1 due to the amide bond of polyacrylamide and to CN stretching in graft copolymer confirmed graft copolymer formed between chitosan and acrylamide. These characteristic bands confirm grafted copolymerization of acrylamide onto chitosan. (Kumbar et al., 2003; Singh et al., 2006)



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Figure 5: Infrared spectra of (a) chitosan and (b) copolymerized chitosanacryl amide

3.6 Differential scanning calorimetry analysis

DSC is an excellent tool to measure the thermal stability as a function of temperature this technique provides a rapid, accurate and precise measurement of the thermal stability. The DSC provides a direct measurement for different heat flows between an inert reference and a sample. The DSC curve of copolymer is depicted in Figure 6. The figures revealed that the pair of exothermic and endothermic peaks at 250 ºC and 273 ºC is characteristic peaks of chitosan. The DSC thermo grams show two other peaks: a wide endothermic peak that span from 80 ºC and an exothermic peak at 146 ºC. The first one can be attributed to the loss of water from chitosan while the exothermic process of the second peak may be attributed to the partial crystallization of polyacrylamide after the loss of water. The second thermal event may be related to the decomposition of amine glucosamine units with correspondent exothermic peak at 295 °C. The obtained results are coherent with previous reported (Guinesi and Cavalheiro, 2006). Thermo gram of chitosangpolyacrylamide shows a broader endothermic peak at 75.2 ºC, due to loss of water molecule, and a high intense exothermic peak at 273.2 ºC, due to decomposition of glycoside unit of chitosan, and from the glass – transition temp, we conclude that chitosangpolyacrylamide has higher thermal stability (Al Karawi et al.).

Figure 6: DSC thermograms of chitosangpolyacrylamide composite.



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3.7 Morphological studies of copolymer

The scanning electron micrograph of chitosan, acrylamide and chitosangpolyacrylamide are shown in Figure. 7 (a), (b) and (c), respectively, the high magnification of copolymer separately depicted as Figure 7 (d). The copolymerization of acrylamide modified the surface morphology of chitosan significantly making it useful for water treatment. It is clearly seen from Figure 7 (c) and (d) that flaked nature of acrylamide was modified with copolymerization process. Moreover, the fibrous nature of chitosan and flaked nature of acrylamide were modified into uniform structure. SEM image of chitosan was smooth and no pores or semipores on the surface. The SEM image of chitosangpolyacrylamide revealed that uniform distribution of polyacrylamide might be improving that characteristic nature of chitosan as well as acrylamide. Distinct difference has been observed in the morphology of chitosan and acrylamide. This characteristic membrane may responsible to allow water with greater adsorbing property (AlKarawi et al.).

Figure 7: Comparative image of (a) chitosan (b) acrylamide (c) chitosangpolyacrylamide (d) High magnified chitosangpolyacrylamide

3.8 Effect of adsorbent dosage in dye effluent treatment

The Table .1 represents the physicochemical parameters and heavy metal content of the dyeing industry effluent collected from an industry from Ranipet Industrial area, (considered to be world’s fifth most polluted sites of the world) and the effect of copolymer adsorbent dosage on dye effluent treatment. All the parameters along with the heavy metal contents were found to be very high than the accepted limits

Various dosages of the prepared chitosangpolyacrylamide graft copolymer have been used to treat dye effluent. The parameters such as COD, TS and ions such as chloride, sulphate and also heavy metals such as copper, chromium, zinc have been decreased drastically with the increase in the adsorbent dosage. The purification of water has been found at minimum amount of sample required (5mg/L). Hence 5 mg was found to be the optimum dosage of grafted copolymer in treating the effluent time (Singh et al., 2009).



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Table 1: Effect of adsorbent dosage in dye effluent treatment

Sample dose (mg/ml) Parameters Initial dye

conc. 1 2 3 4 5

Turbidity mg/l 160 22 6 1 1 0

EC (mmhos/cm) 13300 7549 2540 1480 960 944

TDS mg/l 9310 4335 1778 936 422 404

pH 11.3 8.1 7.7 7.5 7.4 7.4 Total alkalinity mg/l 676 460 444 420 344 221

Total Hardness mg/l 1544 1106 874 492 335 320

Ammonia mg/l 1.2 0.2 0 0 0 0

Nitrite mg/l 0.1 0.1 0 0 0 0.2

Nitrate mg/l 124 85 28 24 12 10

Chloride mg/l 5460 995 476 158 144 120

Fluoride mg/l 1.8 0.5 0.2 0.1 0.1 0.1

Sulphate mg/l 1420 552 248 276 155 120

Phosphorus mg/l 4.8 1.2 0.5 0.4 0.3 0.2

BOD mg/l 3738 1125 746 510 362 220

COD mg/l 22915 1560 958 735 506 320

Iron mg/l 4.5 2 0.1 0 0 0 Iron mg/l 4.526 2.01 0.092 0.000 0.000 0.000

Zn mg/l 62.4 26.7 22.5 12.5 8.4 5.5

Cu mg/L 17.4 8.5 5.2 3.2 2.9 2.1

Co mg/l 45 27 19 15 12 7

Cr mg/l 124 65 46 25 15 7

3.9 Effect of time in dye effluent treatment

Table .2 represents the effect of time on the treatment of dye effluent by the copolymer. On increasing the time, the initial dye concentration reduces. After the treatment for 5 hours all the parameters reduced to the maximum extent. Hence 5 hrs was found to be an optimum treatment time (Guinesi and Cavalheiro, 2006).



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Table 2: Effect of time in dye effluent treatment

Hour Parameters Initial dye conc.

1 2 3 4 5

Turbidity mg/L 160 11 6 1 1 0

EC (mmhos/cm) 13300 4505 2540 980 460 350

TSS mg/l 9310 3510 1778 736 522 335

pH 11.3 8.5 7.65 7.5 7.35 7.35 Total alkalinity mg/l 676 465 320 244 154 120


Ammonia mg/l 1.2 0.66 0.01 0 0 0

Nitrite mg/l 0.1 0.071 0.036 0.025 0.015 0.01

Nitrate mg/l 124 55 28 21 12 11

Chloride mg/l 5460 779 276 167 144 76

Fluoride mg/l 1.8 0.5 0.2 0 0 0

Sulphate mg/l 1420 256 175 98 65 50

Phosphorus mg/l 4.8 2.01 1.11 0.51 0.24 0.11

BOD mg/l 3738 1650 760 624 420 350

COD mg/l 22915 12540 3856 1223 766 450 Iron mg/lit 4.526 2.011 0.022 0.000 0.000 0.000

Zn mg/l 62.4 25.5 21.1 13.7 7.5 3.3

Cu mg/l 17.4 8.2 5.3 2.8 2.1 1.8

Co mg/l 45 24 15 11 7 6

Cr mg/l 124 67 43 25 13 8

3.10 Effect of pH on effluent treatment

The Table 3 represents the effect of pH on dye effluent treatment. The reduction of all the parameters in the effluent by the grafted copolymer was found to be pH dependent. Results showed that there was maximum adsorption of all the parameters in the effluent by chitosan gpolyacrylamide at pH 7. And hence pH 7 was found to be better on treating the waste water (Guinesi and Cavalheiro, 2006). The reactor was started with an initial organic loading rate (OLR) of 0.5 g COD/L.d at a constant hydraulic retention time of 48 h (Mehrdad Farhadian et al., 2007; Puňal, et al., 2000). The study was conducted under ambient environmental



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conditions. The OLR was increased from 0.5 to 1 g COD/L. d by decreasing the HRT stepwise from 48 hours to 24 hours during initial 35 days of operation.

Table 3: Effect of pH on dye effluent treatment

pH Parameters Initial dye

conc. 5 6 7 8 9

Turbidity mg/L 160 55 20 1 12 14

EC (mmhos/cm) 13300 2530 2540 2480 2460

TSS mg/L 9310 2345 1778 120 722 945 pH 11.3 95 7 0 12 25 Total alkalinity mg/l 676 250 120 15 120 150


Ammonia mg/l 1.2 0.05 0.01 0 0 0.02

Nitrite mg/l 0.1 0.045 0.036 0.01 0.025 0.03

Nitrate mg/l 124 55 24 10 12 25

Chloride mg/l 5460 465 176 101 144 154

Fluoride mg/l 1.8 0.7 0.2 0.1 0.1 0.24

Sulphate mg/l 1420 560 248 116 225 229

Phosphorus mg/l 4.8 1.15 0.52 0.36 0.48 0.55

BOD mg/ml 3738 1450 746 420 662 675

COD mg/ml 22915 8111 1458 406 496 500

Iron mg/l 4.5 2.33 0.092 0 0.052 0.02

Zn mg/l 62.4 29.3 20.4 8.4 10.4 15.5

Cu mg/l 17.4 9.3 6.2 3.2 7.9 9.3

Co mg/l 45 26 15 8 10 13

Cr mg/l 124 72 55 6 25 27

On the day 36 the COD concentration of the substrate increased to 2000 mg/L at HRT of 24 h resulting in increase of OLR to 2 g COD/L. d. Then the OLR was increased up to 16 g COD/L. d. by reducing HRT stepwise from 24 to 6 h (Stronach et al., 1987; Ayoob Torkian and Eqbali Hashemian, 2003). The loading pattern and reduction of HRT during the study period are shown in Figure 2 and Figure 3 respectively. The ambient room temperature during most of the period of the study varied between 29 o C and 37 o C.

4. Conclusions



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The graft copolymerizations of chitosan with acrylamide have been done in the presence of CAN as redox initiator and by novel technique U.V. irradiation. The grafting was strongly confirmed by FTIR. The Differential Scanning Calorimetry studies showed that the grafted copolymer has high thermal stability. And the morphological structure by SEM revealed that copolymer is uniformly formed onto chitosan backbone, which showed that the grafted copolymer has improved porosity and fractured structure, which can be responsible for adsorption of molecules. The effects of dosage, time and pH of the medium on adsorption efficiency copolymer were studied for waste waster dye effluent. Significant result has been found for the industrial application. Hence the chitosangpolyacrylamide can be use for waste water treatment at industrial level.

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beneficial effect of chitosan gpolyacrylamide copolymer ... · state in india) is becoming a ......

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