Adsorption Mechanism of Direct Red on Cellulose Acetate from Ananas Comous Leaves

Endang Widjajanti Laksono Fx,  Marfuatun and Siti Marwati

Departement of Chemistry, Education Faculty of Mathematics and Natural Science Yogyakarta State University, Yogyakarta 55281, Indonesia.

Corresponding Author E-mail : endang_widjajanti@uny.ac.id

DOI : http://dx.doi.org/10.13005/ojc/330657

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ABSTRACT:

The study describes the bacth experiment on technical diret red dyesremoval from aqueos solutionusing cellulose acetat prepared from Ananas comous leaves. The Adsorption investigations were carried out in various of time, adsorbent mass, adsorbate concentration, and temperature. The adsorption kinetics followed a pseudo second order reaction. The equilibrium adsorption data was best presented by the Freundlich isotherm. The calculated thermodynamic parameters indicate that the ongoing adsorption process was endothermic and non-spontaneous in nature.

KEYWORDS:

Direct Red; Cellulose Acetate; Ananascomous Leaves; Kinetics; Isotherm Adsorption

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Copy the following to cite this article: Fx E. W. L, Marfuatun M, Marwati S. Adsorption Mechanism of Direct Red on Cellulose Acetate from Ananas Comous Leaves. Orient J Chem 2017;33(6).

Copy the following to cite this URL: Fx E. W. L, Marfuatun M, Marwati S. Adsorption Mechanism of Direct Red on Cellulose Acetate from Ananas Comous Leaves. Orient J Chem 2017;33(6). Available from: http://www.orientjchem.org/?p=40087

Introduction

Water pollution caused by untreated synthetic dye effluents released from textile industries has been concerned. The development of dye production relates the number of dye waste. The textile industry is the main contributor of dye waste into the environment. The characteristic of dye waste are base, hot, high of BOD and COD levels, and containing some dissolved solids. In the dyeing process the dye is partially absorbed by textile material, and the residue(2-50%) goes to water ways[1], or rarely be treated[2] One of synthetic dye which use in Indonesia textile industries generally is direct red. Direct red is a di-azo compound containing several sulfonate groups. It has a soluble nature in water, low price, and easy to use.Unfortunately, it consumes long time to degrade, hence it potentially can be pollutant in water environment. Structure of direct red is shown in Figure 1.

Figure 1: Direct red structure Click here to View figure

Many water pollutant treatment methods, such as coagulation, flocculation, photo catalytic degradation, membrane filtration, microbiological decomposition[i], electro chemical oxidation,[ii], adsorption using fungi biosorbent[iii] have been applied. Adsorption is the process by which one substance(gas, liquid or solid) is taken into the body of another substance and  the most  popular method used to reduce dyes from wastewater[iv], due to its economical and effectiveness removinga variety of pollutants including heavy metals, organic compounds and inorganic compounds[v].Activated carbon has been reported as an ideal adsorbent to reduce the dye was televel in water. However, the activated carbon is less economical, due tothe high production and regeneration costs[vi]. But  the use of activated carbon still requires advanced treatment for suspension, so as not to make new waste[vii]. Therefore, researchers began developing other cheaper adsorbents, such asbentonite, zeolite, and kaolin. Many materials  have been used as adsorbents, such as diatomae [viii]^,[ix]and bentonite [x].Biological adsorbents such as eggshell powder,[xi]peanut shell,[xii] jackfruit leaf powder [xiii]and  banana peels[xiv]have been used to adsorb  dyes. Unfortunately, these adsorbents show  very low ability in adsorbing dyes. Development of cheaper, more efficient, and environmentally friendly adsorbent are of interest. Polymer is one of best adsorbents. The polymer produces less sediment in adsorption process and widely used in batch or column separation method. Poly(N, N-dimethylaminoethyl metacrylate)[xv], polypyrrole,[xvi] and poly(vinyl alcohol) [xvii] have been developed as adsorbents for dye waste. On the other hand, cellulose acetate,a derivative of cellulose,can also be usedas an adsorbent. Cellulose acetate is a biodegradable polymer; the membrane has a sufficiently high mechanical strength and transparency. In addition, cellulose acetate is used aselectrolyte membrane, photographic film, and specialty papers. Exhaustive exploration on the adsorption kinetics involving wastewater treatment   is important to  providing better understanding of the reaction pathways and possible mechanisms involved[xviii]. We are reporting the use of cellulose acetate membrane obtained from leaves of pineapple (Ananas comous) as an adsorbent to remove direct red in water. The equilibrium, kinetics and thermodynamics of dye adsoption by synthesized membranes are discussed

Materials and Methods

Pineapple (Ananas comous) leaves, an agriculturel waste, was obtained from  pineapple farm  in Yogyakarta.  Toluene, ethanol, sulfuric acid, glacial acetic acid, sodium hydroxide,  sodium hypochlorite, sodium chloride, pH buffer solution, technical direct red, and phenol-phtalien,and anhydride acetic acid were  purchased from Merck andwere usedas received without any further purification.

Adsorbent Preparation

Ananas comous leaves were cut into small pieces and dried in the oven at 60^oC and milled into powder. The cellulose was isolated by soaking the dry powder  in a mixture of ethanol and toluene (1:2) for one hour.The cellulose was filter of and dried in 60^oC for 3 hours. The dry cellulose was solvated in 2 M sodium hydrochloride solution for 3 hours to remove lign in, followed by  bleaching process using sodium hypochloride solution. Finally, the cellulose was acetylated using glacial acetic acid, sulfuric acid and anhydride acetic acid.[xix],[xx]

Adsorbent Characterization

The adsorbent was characterized using FTIR method. The FTIR spectra of the cellulose acetate indicates functional groups of before and after adsorption adsorbents. The Adsorption investigations were carried out in batch system in various of time, concentration of adsorbate, and temperature of adsorption. The adsorption measurements were conducted by mixing 0.5 gram of adsorbent in a 100 cm³ Erlenmeyer containing 50 cm³ of dye solution of known concentration. The solutions were agitated using an automatic shaker for a certain of time, and the supernatant solution was separated from the adsorbent by filtration using a What man No. 41 filter paper. The residual dye concentrations were analyzed using UV-Vis  Spectrometer at 496 nm wavelength.

Result and Discussion

Characterization of Adsorbent

The extraction of Ananas comous leaves yielded 20.71% cellulose. The acetylation process of cellulose produce 37.28% acetyl (degree of acetylation ~2)  indicating that the compound was cellulose diacetate. The FTIR spectra of cellulose acetate before and after adsorption are depicted in Figure 2. The absorption at 3749.62 cm^-1,a broad peak at 3464.15 cm^-1 and at 1373.32 cm^-1 represent the free OH vibration, OH (bonded) stretching vibration, and of OH bending vibration, respectively. The peak at 1751.36 cm^-1 represents the stretching vibration of C=O in acetyl groups, while peak at 1049.28 cm^-1 represents the CO stretching. The peak at 1242 cm^-1 relates to the presence of CH deformation. FTIR spectra does not recognize the difference of the  before and after adsorption samples due to the small amount of the adsorbate (ppm).

Figure 2: FTIR Spectra of Cellulose Acetate Click here to View figure

Adsorption Kinetics

The constant rate of adsorption was determined from pseudo first order and pseudo second order equation. Determination of the reaction order wasundertakenusing the optimum contact time of  adsorption. In order to study the constant rate of direct red, the pseudo first order equation, which well-knownLagergren first order equation,was employed,.The value of ln (q_e-q_t) was calculated at different temperature for interval time[i][ii]: Ln

(q_e – q_t) = ln q_e – k₁t                (1)

Where k₁ (min^-1) is the pseudo first order adsorption kinetic parameter, q_e and q_t denote the amount of direct red adsorbed at equilibrium and at any time t. The plot of pseudo first order is depictedin Figure 3. The ln (q_e-q_t) value decreases along with time consumed in the adsorption process.

Figure 3: The plot of Pseudo first order Click here to View figure

The pseudo second order equation in solution was represented by equation 2.[i]

Figure 4: The plot of pseudo second order Click here to View figure

Table 1: Kinetics Parameter of Direct Red Adsorption by Cellulose Acetate

Table 1 shows that R value of Pseudo second order is greater than that of the Pseudo first order, indicating that the adsorption mechanism of direct red obeys the pseudo second order reaction. In this system, the adsorption process was controlled by chemisorptions which involved valence forces through sharing or exchange of electrons between the sorbent and the sorbate. ^20,26 The adsorption process was conducted as a slow process (Fig. 4).

Adsorption Isotherm

Determination of adsorption isotherms was undertakenusing data of adsorption capacity  at various initial concentration of direct red solution.  The experimental equilibrium adsorption data have been tested using Langmuir and  Freundlich isotherm equations. The applicability of these isotherms equation to describe the adsorption process was adjudged by the correlation coefficient  or R values. ^21,27 Langmuir isotherm is determined by plottingthe equilibrium liquid phase concentration (C_e) vs.  Ce/qe, where q_e is the equilibrium adsorption capacity. The Langmuir isotherm is shown in Figure 5.

Figure 5: Langmuir Isotherm Click here to View figure

The plot of Cevs. log q_e gives a straight line with slope 1/n and intercept of log K_F, where K_F is the Langmuir constant. The Freundlich isotherm was described in Figure 6. The parameters of the isotherm and R values are listed in Table 2.

Figure 6: Freundlich Isotherm Click here to View figure

Table 2: The parameters of isotherm

Table. 2 indicates that R value of Freundlich isotherm is greater than 0.949, i.e. the Freundlichgiving the best fit. Freundlich isotherm is based on the assumption that adsorption occurs on a heterogeneous adsorption surface having unequally available sites with different energy of adsorption.²⁸ According with Ayawei et al²⁹ and  Vimonses³⁰,the Freundlich isotherm constant can be used toexplore the favourability of adsorption process.The adsorption process is favourableif the value of  n satisfies the condition  |1|  <  n < |10|.We found thatthe value of n = 1,1759 (1/n = 0,8504) indicating that the adsorption of direct red into cellulose acetate is favourable. The thermodynamic parameters were determined by measuring the effect of temperature on adsorption capacity. We observed that the increase of temperature is accompanied by the increase of adsorption capacity. This implies that the adsorption is endothermic process. The measurable thermodynamic parameters include the change in free energy (DG^o), enthalpy(DH^o), and entropy (DS^o), which may be determined using the following equation^{23, 31}:

ΔG^o = ΔH^o – TΔS^o              (3)

The values of ΔH^o and ΔS^o were calculated by plotting 1/T vs. ln K_d, where K_d is the distribution coefficient. K_d can be obtained comparing q_e to equilibrium liquid phase concentration after time t (C_t).The plot can be seen in Figure 7.

Figure 7: Thermodynamic plot for adsorption Click here to View figure

Based on Figure 7, the values of ΔH^oand ΔS^o  are 22,965 kJ.mol^-1and 60,710 J.mol^-1.K^-1, respectively.  The values of ΔG^o in each temperature is listed in Table 3.

Table 3: The values of Gibbsfree energy

Endothermic nature is indicated by the positive value of ΔH^o, the increase of ΔS^oand the decrease of ΔG^o.³² The positive value of ΔG^o indicates that absorption is nonspontaneous. The positive value of ΔS^o indicatesthe increasein randomness.

Conclusion

The cellulose acetate prepared using Ananascomousleaves is effective for removingthe reactive direct red in aqueos solutions. Adsorption kinetics followspseudo second order reaction. Equilibrium adsorption data presents the Freundlich isotherm. The calculated thermodynamic parameters indicate that the ongoing adsorption process is endothermic and nonspontaneous.

Acknoledgement

This work was supported financially by DIPA Yogyakarta State University,andthe  authors would like to thank Desiyuningfor her help in pre-research.

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