Der Pharma Chemica
Journal for Medicinal Chemistry, Pharmaceutical Chemistry, Pharmaceutical Sciences and Computational Chemistry

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Research Article - Der Pharma Chemica ( 2018) Volume 10, Issue 4

Thermodynamic and Kinetic Studies for Adsorption of Methyl Violet Dye on to Creeson Seeds

Huda N Al-Ani*

Department of Chemistry, College of Science, University of Baghdad, Jadiriya, Baghdad, Iraq

*Corresponding Author:
Huda N Al-Ani
Department of Chemistry
College of Science
University of Baghdad
Jadiriya, Baghdad, Iraq

Abstract

The present investigation describes the adsorption of Methyl Violet (MV) dye onto Creeson (Lepidium sativum) (LS) seeds known as Garden cress from its aqueous solution, has been known centuries ago in eastern regions then spread worldwide. The using of creeson seeds as adsorbent for the removal MV dye was investigated in aqueous solution. Effect of experimental coefficient like connection time, primary concentration of adsorbate (MV) and amount of adsorbent seeds (LS) dose and temperature were evaluated to obtain the optimum condition for adsorption of MV onto Cresson seeds using batch adsorption. The adsorption information were mathematically analyzed using isotherms of adsorption like Langmuir, Freundlich and Dubinin-Radushkevich isotherms to study adsorption mechanism of MV dye onto creeson seed. The isotherms of adsorption were advanced and equilibrium data adjusted well to Freundlich isotherm model. The studies of kinetic indicated that the process of adsorption followed the model of second-order kinetic. The quantities (ΔG0, ΔH0 and ΔS0) were estimated and the obtained ΔG° negative values indicate a spontaneous adsorption process, ΔH° value obtained positive designate to endothermic properties of adsorption process and ΔS° value obtained positive during the adsorption indicate increased randomness.

Keywords

Creeson seed, Methyl violet dye, Adsorption kinetics

Introduction

Artificial dyes of great extent assortment and amount are used by various industries for coloring their eductors [1-3]. Plausible quantity of the dyes appended in the practicability to be left over semifinished and finally find their way to water collection. Presence of dyes in a water collection position earnest cause of danger to the environment like the change in color, nature of the water and makes it infelicitous for human exhaustion. The growing environmental problems caused by dye flowing out have driven plausible research exertions to decrease of dye wastewater. Methyl Violet (MV) is in particular important because of its extensive appliance in antibacterial [4], temper inks, textiles, bacteria categorization and in paints [5,6]. The intake of MV may cause excitation to the breathing apparatus, and swallowing exemplary causes distress to the digestive system [7]. Furthermore, MV dye is rebellious and hard to control to demean because of the existence of three aryl groups, which each one is bonded to N2 atom that interplay with one or two CH3 groups Figure 1 [8]. An extensive range of technologies had been developed for removal by artificial dyes with aqueous solutions to diminution their effect in the environment, inclusive membrane filtration processes [9], adsorption mechanics [10], clotting [11], developed processes of oxidation [12] and processes of ozonation [13]. Between the above-referred to techniques, sorption is higher quality to the different mechanisms in terms which have a low cost, elasticity, modesty of a plan, case of procedure and insensitivity to toxic contaminating [14]. The adsorption is one of the greatest qualified mechanisms can be valid for MV dye removal [15,16] and the mercantile adsorbents as plant seeds are costing much, to examine is perform by some researchers for recognizing low-priced adsorbents [17].

derpharmachemica-Chemical-structure

Figure 1: Chemical structure and 3D structure of MV dye

Agricultural by yields have been considerably studied for pollutant, these contain peat, wood, pine bark, peanut shells, plant seeds, wool, banana pith, compost and leaves [18]. Cresson seeds can employ like an origin of agriculturally-based. The seeds swell upon moistening and once swollen comprise of a rigid core with a cancellate swollen external layer. The gummous layer of blown seeds is a pectinous template, made up of plausible amounts of unesterified galacturonic acid with a large capaciousness of hydration [19,20]. The aim of this study is using Cresson seeds as an adsorbent for the polltant MV dye from waterish solution; study the effect of specific coefficients as, elementary concentration of MV, connection time, adsorbent dose and the temperature for maximum removal of MV dye in its aqueous solutions using UV-visible spectrophotometer; determined the kinetic equation best describe the data obtained; determined the adsorption equation which best describe the equilibrium uptake and finally to calculate the thermodynamic coefficients (ΔHo, ΔGo and ΔSo) for practical execution to Creeson seeds. Study the mechanisms of adsorption proses.

Experimental Section

Materials

Sorbent

Cresson seeds (Lepidium sativum seeds), brownish red in color, were purchased from the local market, prepared as whole seed, the plants producing these seeds grown extensively in Iraq Figure 2. The required quantity of seeds were washed with distilled water then allowed to swell for 30 min and directly used as adsorbent

derpharmachemica-fresh-plants

Figure 2: Cresson dry seeds and fresh plants

Sorbate

The commercial Analytical MV dye appearance green to dark-green powder[with Molecular formula (C25H30ClN3) and Molecular weight- 407.986 g/mol; λmax was 590 nm, Mono isotopic mass 407.212830 Da, EC Number 208-953-6, Melting point: 205 to 215°C, Soluble in water and ethanol, CAS Registry Number: 548-62-9] was used for the preparation of stock solution of 40 mg/l, with dissolving 0.01 g from MV dye with 250 ml distilled water. A series of diluted solutions were prepared (30, 20, 10 mg/l) by fresh diluting of the stock solution, to compute the best λmax using UV-Visible spectrophotometer.

Methods

The experiments of adsorption were executed using batch equilibrium method [21]. Swollen seeds were taken in 250 ml round bottom flask containing 125 ml of MV dye solution. The flasks were placed on a hot plate with magnetic stirrer (Bibby Strlintd, UK) and shaken at 150 rpm at 25°C, Finally predetermined time intervals, adsorbent was dismissed by centrifugation with 150 rpm, the supernatant assayed using UV-visible spectrophotometer. Seeds uptake by the adsorbent at equilibrium (Qe) was computed by following equation:

Qe = (C0 – Ce) V/W (1)

Where, Qe=Amount sorbed in (mg/g) of MV dey, C0=Initial concentration in (mg/l) of MV dey, Ce=Equilibrium concentration in (mg/l) and V=Total volume of solution in (litre) and W=Adsorbent used mass of (Cresson seeds) (gram) [22,23]. Removal percentage or adsorption percentage (%R) were calculated using Equation 2:

%R = [(C0 – Ce)/C0] × 100 (2)

Results and Discussion

Effect of adsorption parameters

Adsorbent

The chemical world phenomena and porous structure of adsorbent generally determines sorption activity. The results for the dye uptake using various amounts were carried out by prepared different concentration of MV dye (2, 3, 4, 5, 6, 7, 8, 9 and 10 mg/l) and calculated the absorbability using UV-Visible spectrophotometer then plot the calibration curve Figure 3.

derpharmachemica-calibration-curve

Figure 3: The calibration curve of MV dye

Effect of connection time

Cresson seeds mixture with (0.5 g) and (125 ml) volume solution with initial concentration (7 mg/l) of MV dye at 25°C for different time (5, 10, 20, 30, 40, 50, 60, 70 and 80 min) and centrifuged. MV concentration were determined as above the contact time effect on adsorption of MV are demonstrated in Figure 4, the equilibrium was attained after shaking for 80 min, there for 70 min was accepted as optimum time for adsorption of MV on Cresson seeds, additionally growth in contraction time did not exhibit any increase in adsorption due to a saturation in a surface sites [24].

derpharmachemica-creeson-seeds

Figure 4: The influence of contact time upon adsorption MV dye onto creeson seeds

Effect of adsorbent doses

A primary concentration MV dye (40 mg/l) were used in conjunction with different amount of swollen creeson seeds of (0.1, 0.3, 0.5, 1 and 1.2 g), the other parameters were kept constant; contact time 70 min, agitation speed 150 rpm; temperature 40°C. MV uptake was found to increase with increase in LS dosage up to 1.2 g of seeds. Therefore optimum creeson (LS) dose was chosen as 1 g for the subsequent experiment as show in Figure 5.

derpharmachemica-adsorbent-dose

Figure 5: The influence of adsorbent dose on adsorption MV dye on to creeson seeds

Effect of primary concentrations

Experiential evaluates for adsorption by different concentration of MV (3, 4, 7, 8, 9 and 10) mg/l are shown in Figure 6. Such as the concentration for MV increase, more and more sites of surface are covered at higher concentration, the capacity of adsorbent obtain consumed caused by non-availability of surface location [21].

derpharmachemica-primary-concentration

Figure 6: The effect of primary concentration at adsorption process using MV dye on to Creeson seeds

Effect of temperature

Experiments were executed at different temperature 25, 30, 35, 40 and 45°C in conjunction with the optimum other parameters, contact time 70 min, adsorbent dose 1 g, agitation speed 150 rpm Figure 7 shows that at 40°C there are the best removal R% and so this temperature was chosen for further experiments.

derpharmachemica-MV-dye

Figure 7: The influence of temperature on adsorption of MV dye onto creeson seeds

Adsorption isotherms

To determine the adsorption capacity and potential for selecting the adsorbent for elimination of MV dye, the topic of adsorption isotherm is essential in selecting the adsorbent. From the batch experiment executed, the most efficient state parameters chosen were; Cresson seeds dose 1 g, contact time 70 min and agitation speed 150 rpm. Adsorption isotherm study was carried out by five different temperatures which were 25, 30, 35, 40 and 45°C. The most common isotherm model was employed for describing the adsorption data, which was adsorption isotherm Figure 8.

derpharmachemica-adsorption-isotherms

Figure 8: The adsorption isotherms on adsorption of MV dye on to cresson seeds using different temperatures

The equilibrium values obtained are depicted in Table 1.

At 25°C At 30°C At 35°C At 40°C At 45°C
Ce Qe Ce/Qe Ce Qe Ce/Qe Ce Qe Ce/Qe Ce Qe Ce/Qe Ce Qe Ce/Qe
0. 033 0. 065 0. 505 0. 179 0. 064 0. 102 0. 027 0. 263 0. 102 0. 141 0. 052 2. 424 0. 130 0. 042 3. 076
0.062 0.075 0.744 0.224 0.062 1.468 0.170 0.116 1.468 0.131 0.047 2.787 0.1812 0.058 3.103
0.555 0.199 3.022 0.558 0.112 4.169 0.771 0.185 4.169 0.711 0.237 2.999 0.659 0.238 2.768
0.600 0.303 3.202 0.803 0.158 1.687 0.331 0.196 1.687 0.525 0.153 3.438 0.682 0.209 3.267
1.971 0.346 3.916 1.912 0.323 2.525 1.327 0.525 2.525 1.391 0.346 4.0179 1.399 0.379 3.684
2.110 0.454 4.867 1.925 0.291 4.494 1.591 0.429 4.494 1.951 0.383 5.094 1.632 0.485 3.367
1.810 0.304 5.950 2.109 0.272 2.266 1.156 0.510 2.265 1.150 0.316 3.636 1.626 0.458 3.654
2.170 0.276 7.876 3.129 0.315 9.331 3.000 0.369 9.331 2.320 0.514 4.518 0.950 0.300 3.166
1.590 0.199 7.969 1.701 0.185 2.176 1.129 0.519 2.176 2.388 0.543 4.402 2.871 0.662 4.340
3.626 0.276 14.038 2.131 0.251 3.006 0.714 0.237 3.006 0.741 0.182 3.071 1.434 0.407 3.526
3.990 0.269 14.805 4.330 0.363 7.458 2.506 0.352 7.458 1.911 0.471 4.124 2.591 0.572 4.532

Table 1: Equilibrium parameters on adsorption of MV dye on to cresson seeds

Langmuir adsorption isotherm

The Langmuir adsorption isotherm is legal for monolayer adsorption on to a level with a limited number of homogeneous situation [24]. It is founded on evaluation of adsorption identity, such as evenly plentiful adsorption locale, monolayer surface covering and no influence between adsorbed type [25,26]. In agreement with the Langmuir isotherm, the adsorption practicability be able to declared as:

Ce/Qe = Ce/Qm + KL/(Qm) (3)

Ce in (mg ⁄l) is equilibrium concentration in solution of MV dye, Qe in (mg/g)=Adsorbed amount at equilibrium per unit weight, Qm in (mg ⁄g)=The adsorption ability at the highest level denominated effective dissociation constant. The linear diagram of Ce⁄Qe VS. Ce propose the suitability of Langmuir isotherm (Figure 9). The assess of Qm and KL were computed by the slope and intercepts of the charts are listed in (Table 2). Langmuir constants relates to adsorption ability and rate of adsorption consecutively.

derpharmachemica-Langmuir-adsorption

Figure 9: The Langmuir adsorption isotherm on adsorption of MV dye onto cresson seeds

T (°K) Langmuir isotherm results
Qm K L R2
298 0.275 9.676 0.963
303 0.478 0.630 0.878
308 0.479 2.762 0.831
313 1.103 0.352 0.840
318 2.109 0.167 0.795

Table 2: Langmuir parameters of adsorption isotherm with their correlation coefficient on adsorption of MV dye on cresson seeds

The linearity of the plots (0.795 → 0.963) at different temperature as show in Table 2 in Langmuir isotherm model.

Freundlich adsorption isotherm

Batch isotherm data fitted to the linear format with the Freundlich adsorption isotherm (Table 3) which is commonly expressed by sequential Equation [27].

Freundlich isotherm Results
T (°K) Kf n R2
298 0.227 2.899 0.815
303 0.169 1.629 0.952
308 0.135 2.041 0.783
313 0.261 1.217 0.988
318 0.403 1.456 0.759

Table 3: Freundlich isotherm model parameters to the adsorption of MV dye on cresson seeds

LnQe=LnKf + (1/n) Ce (4)

Where, Kf and n are computed from Figure 10 and data are provided in Table 2. These are signal of the adsorption capacitance and adsorption strength consecutively. The linearity of the plots (0.759 → 0.988) at different temperature is evident and the result show that (n) is more than (1) that indicates that adsorption is favorable as show in Table 4, favorable sticking of adsorbate to adsorbent [28]. This assistance the suitability of Freundlich isotherm indicating that adsorption by swollen Creeson seeds may be governed by physisorption. From the values of the regression coefficient R2 listed in Table 4, Freundlich isotherm gave good and fitted better than Langmuir isotherm from the calculated results for experimental data R2.

derpharmachemica-model-adsorption

Figure 10: Freundlich isotherm model of adsorption of MV dye on cresson seeds

At (298)° K At (303)° K At (308) °K At (313)°K At (318) °K
LnCe LnQe LnCe LnQe LnCe LnQe LnCe LnQe LnCe LnQe
-3.404 -2.737 -1.720 -2.749 -3.144 -2.776 -1.958 -2.959 -3.144 -2.775
-2.891 -2.597 -1.496 -2.785 -1.772 -2.157 -2.032 -3.0533 -1.772 -2.157
-0.511 -1.162 -0.584 -2.187 -0.261 -1.688 -0.340 -1.439 -0.260 -1.688
-0.029 -1.193 -0.213 -1.845 -1.106 -1.628 -0.644 -1.879 -1.106 -1.628
-0.302 -1.063 0.648 -1.130 0.283 -0.643 0.330 -1.061 0.283 -0.643
0.747 -0.791 0.654 -1.229 0.255 -0.846 0.668 -0.959 0.255 -0.846
0.593 -1.190 0.746 -1.302 0.145 -0.673 0.139 -1.152 0.145 -0.673
0.775 -1.289 1.141 -1.156 1.203 -0.997 0.842 -0.666 1.203 0.998
0.464 -1.612 0.531 -1.686 0.121 -0.656 0.870 -0.616 0.121 -0.656
0.129 -1.356 0.757 -1.381 -0.337 -1.437 -0.299 -1.703 -0.337 -1.438
1.384 -1.311 1.312 -1.998 0.893 -1.045 0.648 -0.752 0.892 -1.044

Table 4: Freundlich isotherm parameters of adsorption and their correlation coefficient on adsorption of MV dye on cresson seeds

Dubinin-Radushkevich isotherm

This adsorption isotherm model was selected to calculate the quality porosity of biomass and the seeming energy of adsorption. The represented model is using sequential Equation 5:

Qe =Qs e-Kad Ԑ2 (5)

Ln Qe = Ln Qs - Kad Ԑ2 (6)

Where, Kad is the isotherm constant (mol2.J-2), Qs is the Dubinin-Radushkevich isotherm constant connected to level of sorbate sorption by sorbent level [29,30].

E (sorption energy) = 1/√2Kad (7)

Ԑ = R T Ln [1+1/Ce] (8)

A diagram between ln qe against Ԑ2 for sorbents, to submit straight lines to suggest an adjustment of isotherm to the experimental data. The obvious energy (E) of adsorption from Dubinin-Radushkevich isotherm model is able to calculate by relation given as Equation 7 [31]. In (Tables 5 and 6) show the height value of E=5000 J.mol-1, that indicates that the adsorption is physisorption show Figure 11.

At (298) °K At (303) °K At (308) °K At (313) °K At (318) °K
LnQe Ɛ 2 LnQe Ɛ 2 LnQe Ɛ 2 LnQe Ɛ 2 LnQe Ɛ 2
-2.737 73170151 -2.7488 22549901 -2.776 66577894 -2.9599 29559650 -2.775 32654557
-2.5967 53252129 -2.785 18302064 -2.157 24398784 -3.0533 31437740 -2.157 24566648
-1.1617 5902756 -2.187 6693774 -1.688 4538839 -1.439 5215264 -1.688 5952397
--1.1931 3076678 -1.845 4116652 -1.628 12693844 -1.879 7692924 -1.628 5690521
-1.063 1879657 -1.130 1123131 -0.643 2068555 -1.061 1985137 -0.643 2030991
-0.791 923783 -1.229 1110768 -0.846 1559529 -0.959 1158447 -0.846 1595141
-1.190 1187618 -1.302 955793 -0.673 2547418 -1.152 2648691 -0.673 1604506
-1.289 881741 -1.156 488060 -0.997 452163 -0.666 869008 0.998 3611289
-1.612 1461358 -1.686 1356912 -0.6564 2638387 -0.616 827732 -0.656 62369
-1.356 364144 -1.381 939480 -1.437 5028452 -1.703 6936560 -1.438 1954698
-1.311 307022 -1.998 273986 -1.0435 773048 -0.752 1198358 -1.044 743912

Table 5: The experimental data of Dubinin-Radushkevich isotherm (D.R.) isotherm on adsorption of MV dye onto cresson seeds

Temperature (°K) Kad (mol2.J-2) Qs (mg.g-1) E (kJ/mol) R2
298 2 × 10-8 0.2272 5000 0.859
303 8 × 10-8 0.2792 2500 0.860
308 3 × 10-8 0.3745 4100 0.742
313 7 × 10-8 0.4132 2700 0.921
318 6 × 10-8 0.5091 2900 0.491

Table 6: The calculated data of Dubinin-Radushkevich isotherm (D.R.) isotherm

derpharmachemica-isotherm

Figure 11: The Dubinin-Radushkevich isotherm (D.R.) isotherm on adsorption of MV dye on to Cresson seeds

Kinetics

Lagergren kinetic rate equation

The equation of Lagergren kinetics has been mainly used for the adsorption of an adsorbate from an aqueous solution [32]. Lagergren authentic paper declared the pseudo-first order rate equation for liquid-solid adsorption array in 1898 and was summarize as follows Equation 9:

Ln (Qe-Qt) = LnQe-K1t (9)

The pseudo second-order equation as equation (10), which applied to empirical data:

t/Qt = 1/K2 Qe2 + t/Qe (10)

Where, Qe and Qt respectively are the adsorption capacities at equilibrium and at (t) time in (mg g-1). K1 in (min-1)=Adsorption rate constant for pseudo-first order [33]. Where, K2=Constant of adsorption rate for pseudo second-order in (g/mg. min) and (t) is time in min show Figure 12. The parameters obtained by the application of the two kinetic models were reported in Table 7.

derpharmachemica-kinetic-equation

Figure 12: The model of pseudo first-order kinetic equation for adsorption of MV dye on cresson seeds

At (298) °K At (303) °K At (308) °K At (313) °K At (318) °K
Time
(min)
Ln
(Qe-Qt)
t/Qt Time (min) Ln
(Qe-Qt)
t/Qt Time (min) Ln
(Qe-Qt)
t/Qt Time
(min)
Ln
(Qe-Qt)
t/Qt Time
(min)
Ln
(Qe-Qt)
t/Qt
5 -2.392 46.664 5 -3.668 57.654 5 3.156 68.399 5 -2.38 34.602 5 -2.553 32.272
10 1.961 17.289 10 -4.061 99.255 10 1.703 203.045 10 -2.08 89.102 10 -3.013 54.444
20 -1.598 161.079 20 -2.526 100.099 20 0.887 210.084 20 -2.782 114.187 20 -3.477 99.056
30 -2.828 215.123 30 -5.116 282.353 30 -6.812 262.467 30 -4.287 164.745 30 -3.826 142.18
40 -2.645 313.603 40 -3.487 363.636 40 -2.24 423.28 40 -3.016 212.653 40 -4.351 182.648
50 -3.252 312.769 50 -4.234 511.509 50 -4.493 478.377 50 -3.079 261.643 50 -4.509 226.143
60 -3.393 363.665 60 -4.923 571.565 60 -3.989 617.284 60 -3.244 302.877 60 -5.573 262.009
70 -3.619 407.545 70 -5.719 642.378 70 -4.034 714.286 70 -3.355 346.198 70 -5.878 304.347
80 -4.466 427.608 80 -6.223 57.654 80 -4.092 808.081 80 -3.778 364.602 80 -5.998 349.112

Table 7: The calculated data of Lagergren kinetic rate equation on adsorption of MV dye on to Cresson seeds

The value of the rate constant calculated from the equations of pseudo first-order and Pseudo second-order which found R2 value for equation of pseudo first-order is=0.578 and for the second order is 0.827 more than the value of pseudo first-order equation, that suggesting that the interaction between the seed and the MV dye follow the pseudo-second order mechanism as show in Figure 13 and Table 8.

derpharmachemica-equation-model

Figure 13: The kinetic equation model of pseudo second-order for adsorption of MV dye on cresson seeds

  Pseudo first - order Pseudo second - order
T (°K) K1 Qe R2 K2 Qe R2
298 0.052 0.693 0.459 0.891 0.182 0.937
303 0.033 0.046 0.574 -4.826 0.103 0.975
308 0906 4.317 0.512 2.139 0.105 0.979
313 0.016 0.084 0.377 0.688 0.216 0.993
318 0.049 0.089 0.966 1.306 0.239 0.999

Table 8: Parameters of kinetic models to adsorption with MV dye on cresson seeds

Where, Keq is the equilibrium constant, Qe is concentration at equilibrium of solid phase (mg⁄g), Ce is concentration at equilibrium for liquid phase (mg ⁄ l) and T=An absolute temperature and R=Gas constant [34]. The values of ΔH° and ΔS° computed from slope and intercept using Vant Hoff plots Figure 14 and are given in Table 9.

derpharmachemica-adsorption

Figure 14: The plot of Vant-Hoff between Ln Keq VS 1⁄T on the adsorption of MV dye onto creeson seeds

T (°K) 1/T Keq LnKeq ∆H°
(J.mol-1)
∆G°
(J.mol-1)
∆S°
(J.mol-1.K- 1)
298 0.00336 1.1246 0.1174 9037.3180 -290.377 31.3009
303 0.00330 1.1696 0.1566   -393.959 31.1253
308 0.00323 1.2112 0.1916   -489.806 30.9322
313 0.00319 1.3300 0.2852   -740.921 31.2404
318 0.00314 1.4130 0.3457   -912.441 31.2885

Table 9: Thermodynamic parameters for adsorption of MV dye on creeson seeds

When the system temperature is increase, the degree of adsorption increase, this become clear from Keq values which increase with increase the temperature, which means endothermic process, this verified by ΔH° positive values. The positive value of ΔS° the change in entropy, propose by increased randomness during the process of adsorption. The ΔG° with negative value suggest that adsorption is spontaneous. The equilibrium values obtained are depicted in (Table 9).

Conclusions

This study confirmed that Creeson seeds can be adopted in reality for removal of MV dye in solution. The removal efficiency reaches 76% in some examples. The adsorption process based on solution with temperature effect. The adsorption process was best fitted with Freundlich adsorption model and kinetics fitted to pseudo-Second order model. According to experimental consequence, creeson seeds is recommended as an available and safe biosorbent to the removal. Parameters of thermodynamic as ΔH°, ΔS° and ΔG° were computed, which demonstrated that the adsorption was endothermic nature and spontaneous process, which was evident by increasing the randomness of the dye at the solid and liquid interface.

References

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