Journal of Chemical, Biological and Physical Sciences Modification of ...

JCBPS; Section B; Feb.2015–Apr.2015, Vol. 5, No. 2; 1700-1710.

E- ISSN: 2249 –1929

Journal of Chemical, Biological and Physical Sciences An International Peer Review E-3 Journal of Sciences Available online at www.jcbsc.org

Section B: Biological Sciences CODEN (USA): JCBPAT

Research Article

Modification of Wood by Grafting of Carboxylic Acid Functions Using Acrylic Acid A. Kassale, K. Barouni, M. Bazzaoui, A. Albourine* Team chemistry of Coordination laboratory materials and environment, Faculty of science, Université Ibn Zohr, B.P.: 8106 cited Dakhla. Agadir, Morocco. Received: 11 March 2015; Revised: 21 April 2015; Accepted: 26 April 2015

Abstract: The aim of this work is the preparation of other supports to replace traditional support used in the purification of effluent from textile industry. It’s in this context that we are interested in the preparation of sawdust grafted by carboxylic functions using acrylic acid (A.Ac).In this study we audited several parameters: the nature of the solvent, the acrylic acid volume, the solvent, concentration of KMnO4, contact time and temperature. To confirm the results obtained we have used the following analysis technique: the infrared spectroscopy (I.R), electron microscopy (SEM) and mass gain. Key words: wood, grafting, acrylic acid, cellulose, adsorption.

Résumé: Le but de ce travail est la préparation d'autres supports pour remplacer les supports traditionnels utilisés dans l'épuration des effluents de l'industrie de textile. c'est dans ce contexte que nous nous sommes interéssés à la préparation de la sciure de bois greffé par des fonctions carboxyliques en utilisant l'acide acrylique (A.Ac). Dans cette étude nous avons vérifiés plusieurs paramètres à savoir: la nature du solvant, le volume d'acide acrylique, le volume du solvant, la concentration de KMnO4, le temps de contact et la température.Pour confirmer les résultats obtenus nous avons utilisés les technique d'analyse suivantes: La spectroscopie infra-rouge (I.R), la microscopie électronique à balayage (MEB) et le gain de masse. Mots clés: bois, greffage, acide acrylique, cellulose, adsorption. 1700

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INTRODUCTION The metals and dyes constitute the focus of many environmental concerns because of their nonbiodegradable and polluting nature. There exist several physicochemical processes/ methods for removal and / or recovery of colored materials and dyes from effluents, and the adsorption is one of the most effective1,2. Because the adsorbent is one of the key factors determining the effectiveness of any adsorption processes, the scope of many studies have been constructed on the basis of investigation of alternative adsorbents which suitable to particular operations. Taking the adsorption of dyes and colored materials, the usability of various natural and synthetic adsorbents have been studied, such as chitin and chitosan3, wool carbonized waste,4, peat 5,6, bagasse pith7,8, maize cob9, banana pith10, hard wood saw dust 6,11, cotton waste, hair, bark and rice husk12, tea waste ash13, agricultural residues14,15, clay16,17 and fly ash18. Usually, the effectiveness of any adsorption process largely depends on the physicochemical properties of the adsorbent used. Thus, the regenerability, availability and operational costs coming out are becoming of prime importance aspects in adsorption processes. It is in this context that we are interested in the use of natural supports (sawdust), as locally available material that allows the decontamination of dyes. The material is used in several works for the depollution of industrial wastewater19,20. However, their adsorbent power is limited to certain molecules by chemical incompatibilities. It is then necessary to change the chemical nature of their surface to create an affinity between this area and the species to adsorb. Thus, various recent works has gone into the chemical modification of polymers to establish the polluting molecules21, 22. 2. MATERIAL AND METHODS 2.1 Modification of sawdust: Wood is a material of biological, done mainly cellulose. It is revolving, variable and degradable. The physico-chemical properties of wood (heats of pyrolysis, density, permeability) vary greatly, depending on the different species of wood. The sawdust used in this study is sawdust of particle size between 0.3 and 0.5 mm FIR. The modification of wood by acrylic acid is done in two steps: • Step 1:10 g of sawdust are treated with a solution of KMnO4 (0, 016 M) for 2 hours at room Temperature. After spinning and rinsing with distilled water, the wood sample is dried at Room temperature for 24 hours (figure 1)

Sawdust --OH

KMnO4

Sawdust --O

• Step 2:1g of sawdust treated with KMnO4 mixed with acrylic acid (A.Ac) dissolved in n-hexane is heated under reflux. After a time of contact determined with monomer grafting, sawdust is wrung out, washed with distilled water and then with acetone and then extracted the soxhlet apparatus with acetone for 6 hours. The sawdust is finally dried in an oven at 60°C for 24 hours. The reaction of cellulose grafting is described23 in figure 2.

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A. Kassale et al. O Hexane

Cell

+

O

Cell

O

CH2CH2C-OH

o 70 C

OH

O

acrylic acid

Figure 2: Reaction of grafting of cellulose from sawdust by the Ac. A. To control the effectiveness of the grafting, are calculated the performance of grafting measurement of mass gain using the following relationship:

%G =

estimated

by

m f – mi . 100 mi

mi: initial mass of support. mf: final mass of support after grafting. 2.2 Parameters influencing grafting (a)Influence of the nature of the solvent: The nature of the solvent has a great influence on the grafting of acrylic acid. For this we make grafting tests in different solvents. All tests are carried out for 10 hours in 10 ml of solvent. The reaction is conducted at temperature of 70°C. Figure 3 shows yields of grafting for different solvents.

performance of grafting (%)

25

20

15

10

5

0 Hexane

Toluène

xylène

Benzene

Figure 3: Effect of the nature of the solvent on the performance of grafting (m = 0.5 g; 0.044 mmol of Acrylique acid; 10 ml of solvent, t = 10 hours; T = 70 ° C). We note, that the grafting of acrylic acid on wood is more effective compared to other solvents hexaneacting. Note that thehexane is more apolar than others, so acrylic acid would become more accessible to 1702


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the active sites of wood.Recall that in the benzene, the reaction is performed in a rushing and that this sol vent unlinks molecular aggregates of acrylic acid24,25. Hexane is a solvent suitable for the reaction of grafting of acrylic acid on wood using KMNO4. It is relatively inexpensive and can be recovered finally reaction. (b) Influence of the volume of hexane: The amount of hexane has a significant influence on the performance of grafting: in excessive amounts, the material degrades; in too small quantities it does not enough swelling of the wood to allow the reaction26. 0.044 mmol of acrylic acid are added to 0.5 g of sawdust treated with KMnO4 for 10hours at70 °C. The results obtained for different volumes of hexane are illustrated in figure 4.


25 20 15 10 5 0

6

8

10

15

20

25

30

Volume d'hexane (ml)

Figure 4: Effect of the volume of hexane of grafting of wood performance (m = 0.5 g; 0.044 mmol of Acrylique acid; t = 10 hours; T = 70 ° C). The grafting yield increases with the increase in the amount of 10 ml, beyond which, observed a decrease in the yield of grafting.

hexane up

to a value

equal

to

(c)Influence of the concentration of KMnO4: We treat 0.5 g of sawdust by KMnO4 by varying the concentration of the latter while setting the other parameters at the optimum values (3 ml of acrylic acid in the presence of 10 ml of Hexane to 70 °C for 10 hours). The results are shown in figure 5. Figure 5 shows an increase in the yield of grafting of sawdust by acrylic acid at a concentration of 0.016 mol / l KMnO4. After this value, there is a decrease in the yield of grafting. As quoted it, the optimal value for the concentration of KMnO4, corresponds to the superposition of boot and manganese ions termination reactions. As a first step, the increasing amount manganese ions give rise to a growing number of free radicals on the cellulose. Where a gradual increase in the percentage of grafting to a certain maximum. Beyond which occurs endings of chains by reaction of their active ends with ion manganese 25, 27. 1703


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25 20 15 10 5 0

0.008

0.01

0.016

0.02

0.025

0.03

0.035

0.04

0.05

Concentration of KMnO4 (mol/l)

Figure 5: Effect of the concentration of KMnO4 of grafting of wood performance (m = 0.5 g; 0.044 mmol of Acrylique acid; 10 ml of hexane; t = 10 hours; T = 70 ° C). (d) Influence of reaction time: 0.5 g of KMnO4 treated wood sawdust is put in contact with 3 ml of acrylic acid in the presence of 10 ml hexane at 70 °C for a time between 2 hours and 24 hours (figure 6).


25 20 15 10 5 0

2

4

6

8

10

14

18

24

Time (h)

Figure 6: Effect of the time of grafting of wood performance (m = 0.5 g; 0.044 mmol of Acrylique acid; 10 ml of hexane; T = 70 ° C). We are seeing an increase in the yield of grafting the first 10 hours up to a maximum equal to 21.2%. Beyond this time, we notice a decrease in performance of grafting. This result can be explained by the very rapid swelling of cellulose which can cause its dissolution after 10 hours of contact28,29. (e) Influence of the quantity of acrylic acid: 0.5 g of sawdust treated with KMnO4 in the presence of 10ml of hexane for 10 h at T = 70 °C are brought into contact with varying amounts of acrylic acid (figure 7).

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25 20 15 10 5 0

0.007

0.014

0.021

0.029

0.036

0.044

0.051

Quantity of Ac.A (mmol)

Figure 7: Effect of the quantity of acrylic acid grafting performance (m = 0.5 g, 10 ml of hexane; t = 10 hours; T = 70 ° C). Figure 7 shows that there is an optimal value for a quantity of acrylic acid, 044mmol; this is probably explained by the formation of homopolymer which limits the rate of fixation27. (f) Influence of reaction temperature: We vary the temperature of reaction between 30 °C and 120 °C, working in optimum conditions. The initial mass is equal to 0.5 g. The results are shown in figure 7. From the results obtained, we note the following points:  Grafting yield is less than 6% for temperatures below 50 ° C, these conditions are insufficient for the activation of the reaction.  Temperatures between 60 and 80 ° C to accelerate the speed of the reaction of grafting. Where performance of grafting gradually increases until it reaches a temperature of 70°C maximum. After this temperature we see a very rapid decrease in the yield of grafting.


25 20 15 10 5 0

30

50

60

70

80

90

100

120

Température of grafting (°C)

Figure 7: Effect of temperature on the yield of grafting (m = 0.5 g, 0.044 mmol of acrylique acid; 10 ml of hexane; t = 10 hours). 1705


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2.3 Characterization of graft support (a) Characterization by spectroscopy (IR): The IR spectra recorded before and after grafting of wood are shown in figure 8. Comparison of Spectra FTIR of non-grafted wood fibres and grafted wood fibres reflects the following changes:  The strip to 1657 cm -1 characteristic of H2O molecules absorbed for wood grafted by Acrylic acid becomes less intense.  The Strip to 1735 cm -1 assigned to the C═O stretching vibrations, becomes more intense for wood grafted by acrylic acid.  The Strip to 3410 cm -1 characteristic of groups OH becomes wider and less intense in the Spectrum of the graft wood: attributed to groups OH carboxylic acid function. It can be concluded that the FTIR spectroscopic study confirms the grafting of carboxylic Functions on the wood. (b) Characterization by scanning electron microscopy (SEM): Figure 9 represents the media SEM images and to observe a significant change in the morphology of the brackets after grafting. Indeed, examination of wood grafted and non-grafted wood morphology shows that the structure of graft wood appears grainy and becomes less fibrillar. This can be explained by the introduction of the chains grafted in the woods which turns into grains do not cover the entire surface. We also note the presence of a few pores that may be interesting for the extraction of pollutants.

Before the grafting

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After the grafting

Figure 8: The IR spectra recorded before and after grafting of wood (a

(b

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(a'

(b'


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A. Kassale et al.

(c

(c'

Figure 9: Images SEM of cellulosic materials: (a) and (a') wood not grafted, (b), (b'), (c) and (c') wood grafted with Ac.A. 2.4 Estimation of the quantity of functions acids monoester grafted on the wood The determination of the acidic functions occurs on 0.15 g of medium mixed with 5 ml of H2SO4 (0.1 N) and 50 ml of distilled water. A determination in return by soda (0.1 N) followed by pH-Metry permits to determine the quantity of acid per gram of product, by the following expression 23:

(

A t mEqH + / g

)

=

Vi – V0 . 0,1 m

m = mass of support (g) Vo = volume (ml) of NaOH (0, 1N) used to neutralize 5 ml of H2SO4 (0, 1N). Vi = volume (ml) of NaOH (0, 1N) titled for the product. The amount of monoester expressed as a percentage is given by the following expression:

A . B  100  −3 M (%) =  At – 0  . B . 10 .MM 1000  

and

B =

100 100 + % GM

A0 = acidity of initial support. At = acidity of the modified wood. MM = molecular mass (g/mol) Acrylic acid. % GM = mass percentage gain. The results are grouped in the table 1:

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Table 1: Estimation of indices of acidity and the amount of monoester trained on grafted Materials. Capacity ( mEqH+/g ) Gain mass Samples %

Equivalent volume (ml)

monoester At

AGM

( found )

(calculated )*

M%

nongrafted wood

--

12,5

0,38

--

--

B.A.Ac

21,2

13,9

2,32

2,96

21,04

Acidity AGM is given by this relation:

A GM =

GM . 1000 MM

The estimation of acidic sites of media grafted with succinic anhydride from gain mass (AGM) and by the determination allows us to confirm the grafting of groups carboxyl on the different media used. 3. CONCLUSION The experimental study that we made shows that can be grafted functions on the sawdust.

successfully

from

the

carboxylic

In this study:  The quantity of acrylic acid is fixed at 0.044 mmol and the temperature to 70°C. The maximum grafting yield for a reaction time equal to 10 hours for 0.5 g of support.  Hexane can improve the responsiveness of acrylic acid with support and achieve efficiencies of grafting about 21.2%.  These results are in good agreement with the data from the literature30  FTIR infrared spectroscopic study, allows to highlight the grafting of carboxylic acid groups on wood fibers.  Examination by scanning electron microscopy (SEM) of the morphology of the obtained Materials, shows that features grafted on to the wood do not completely cover the surface. But confirms the introduction of carboxylic ester functions on the surface of the media.  After theestimate of the amount of acidic functions, we can say the prepared media have number of important free acidic sites, where the interest used to secure the pollutants. REFERENCES 1. D. Ghosh, K.G. Bhattacharyya, Appl. Clay Sci ; 2002, 20,295. 2. N. Kannan, M.M. Sundaram, Dyes Pigments, 2001, 51, 25. 1709


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