Extraction of Citric Acid and Maleic Acid from Their Aqueous Solutions

Article Cite This: J. Chem. Eng. Data XXXX, XXX, XXX−XXX

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Extraction of Citric Acid and Maleic Acid from Their Aqueous Solutions Using a Phosphorus-Bonded Extractant, Tri‑n‑octylphosphineoxide, and a Secondary Amine, Dioctylamine ̇ Erdem Hasret,† Ş ah Ismail Kırbaşlar,† and Hasan Uslu*,‡,§ †

Engineering&Architecture Faculty, Chemical Engineering Department, Istanbul University, Avcılar Istanbul, Turkey ̇ ̇ Faculty of Healthy Sciences, Istanbul Esenyurt University, Esenyurt Istanbul, Turkey § Chemical and Materials Engineering Department, Faculty of Engineering, King Abdulaziz University, Jeddah, Saudi Arabia ‡

ABSTRACT: The aim of this study is to investigate the extraction of citric acid and maleic acid from their aqueous solutions using different solvent−extractant mixtures in order to find the most effective composition for the extraction. Citric and maleic acids are chosen as the carboxylic acids due to their commercial worth in the industrial processes. Carboxylic acids are recovered from their aqueous solutions by reactive extraction, a promising liquid−liquid extraction technique, using trioctylphosphineoxide (TOPO), and a secondary amine called dioctylamine (DOA). TOPO has been chosen as an extractant since it has low water solubility, high stability, and it is more environmentally friendly than the amine-type extractants. For other amine extractants used in reactive extraction processes, there is a lack of study in the literature about the extraction of these acids with DOA. Extractants were dissolved in nine different solvents (butanol, decanol, octanol, isoamylalcohol, octane, decane, methylisobutylketone, and diisobutylketone) having different chemical structures. All experiments were carried out at 298.15 K. Comparisons of the results were made using the distribution coefficient (D), loading factor (Z), and the extraction yield (%E). It has been observed that a considerable amount of citric acid and maleic acid extraction was achieved using DOA (in the range of 13.95−99.19% and 31.94−99.41% according to the diluent used for citric acid and maleic acid, respectively) compared to that achieved with TOPO (in the range of 0.81−67.12% and 16.25−89.33% according to the diluent used for citric acid and maleic acid, respectively).

1. INTRODUCTION There is a colossal request for chemicals which could be integrated from biomass or inexhaustible assets. Chemical companies are always searching for ecological amiable courses to create biofuel and biochemicals which are sought after on the planet market. Many carboxylic acids are delivered by microorganisms; however, the test lies in their generation by a maturation method utilizing sustainable carbon sources as the preferred stock.1,2 Citric acid and maleic acid are important chemicals which are used in many industrial productions through fermentation. These acids are used as acidulants in food, confectionary, beverage, pharmaceutical (10%), and soluble aspirin preparation,3 and must be purified for use in industrial applications. The fermentation technique is the most picked strategy for the generation of carboxylic acids which are utilized as a part of drug and sustenance added substance ventures. These acids are created as roughly 8% in mass, and they should be separated from solution for use. Refining and precipitation,4 membrane,5,6 and adsorption7,8 strategies have been utilized for isolating numerous acids from fluid and other media © XXXX American Chemical Society

arrangements; however, these days reactive extraction is the most encouraging technique. Reactive extraction is more and more being utilized as a part of the separations procedure. This technique depends on the acid−amine complex development. Moreover, proper diluents ought to be utilized for diminishing the viscosity of the amine and aiding the formation of the complex of acid and amine after the reactive extraction in the organic phases. It has been seen from literature that some applications of separation and purification of citric acid and maleic acid are available. Thakre et al. studied extraction of citric acid by using tri-n-butylphosphate, tri-n-octylamine, and Aliquat 336 in butyl acetate, decanol, and benzene at isothermal conditions. All experimental data were modeled and optimized by the linear solvation energy relationship (LSER) model.9 Chanukya et al. focused the extraction and isolation citric acid from Fruit juices by the supported liquid membrane which was produced by Received: June 19, 2017 Accepted: December 11, 2017

A

DOI: 10.1021/acs.jced.7b00562 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data

Article

Table 1. Physical Properties of Chemicals Used in This Study chemical

IUPAC name

MW (kg·kmol−1)

density (kg·m−3)

supplier

purity (%w)

ref

n-decane n-octane 1-butanol 1-decanol 1-octanol isoamyl alcohol ethyl methyl ketone isobutyl methyl ketone diisobutyl ketone tri-n-octylphosphine oxide dioctylamine citric acid maleic acid

decane octane butan-1-ol decan-1-ol octan-1-ol 3-methyl-1-butanol butan-2-one 4-methylpentan-2-one 2,6-dimethylheptan-4-one 1-dioctylphosphoryloctane N-octyloctan-1-amine 2-hydroxy-1,2,3-tricarboxylic acid (2Z)-but-2-enedioic acid

142 114 74 158.29 130 88 72 100 142.23 38 664 24 146 192.12 116.07

730 703 810 840 827 810 805 801 806 831 790 1665 1590

Merck Merck Merck Merck Merck Merck Merck Merck Merck Acros Acros Merck Acros

≥94 ≥99 ≥99.5 ≥99 ≥99 ≥98 ≥99 ≥99 ≥96 ≥99 ≥99 ≥99 ≥99

16 16 16 17 16 16 16. 16 17 CASRN: 78-50-2 CASRN: 1120-48-5 18 19

2.2. Methods. Aqueous solutions of citric acid and maleic acid were prepared by dissolving in distilled water with concentrations of 0.453 mol·kg−1 and 0.749 mol·kg−1, respectively. Organic phases were obtained by mixing TOPO with nine different diluents (1-butanol, isobutyl methyl ketone, ethyl methyl ketone, isoamyl alcohol, diisobutyl ketone, noctane, 1-octanol, n-decane, 1-decanol) and also mixing DOA with the same diluents. These TOPO + diluent mixtures and DOA + diluent mixtures were made to help us find the optimum concentration of organic phase that can be used in the reactive extraction processes. Equal volumes (10 mL) of the organic and aqueous phases were mixed in an Erlenmeyer flask. These prepared two-phase systems were shaken in a temperature controlled Shaker at 150 rpm and 25 °C for 2 h. After the equilibrium, the flasks were let standing to achieve a perfect separation of the phases. Once the phases were separated, the carboxylic acid concentration in the aqueous phase was found by base titration with 0.1 N NaOH using phenolphthalein indicator. The volumes of the both phases before and after extraction have been measured. The organic phase concentration of citric and maleic acids after extraction was calculated by mass balance.

polytetrafluoroethylene. Aliquat-336, toluene, and sodium carbonate+sodium bicarbonate were used as the carrier phase.10 Djas and Henczka investigated the separation of citric acid from aqueous solution by supercritical carbon dioxide extraction method. Tri-n-octylamine was used in the ScCO2 method so that reactivity can be done with citric acid. According to the results complexes between acid and amine in the ratio (1:1) were reported.11 Rani et al. reported that uses of Alamine 336 in octan-1-ol is an efficient extractant for extracting citric acid from aqueous media. The mass transfer coefficient was determined based on the Hatta number.12 Bayazıt et al. used two different amine extractants such as a secondary (Amberlite LA-2) and tertiary (Tridodecylamine) for extraction of citric acid from aqueous solution. The highest extraction efficiency was determined as 99.05% with Amberlite LA-2 dissolved in octan-1-ol.13 Rahmanian et al. tried to extract maleic and phatalic acid by supercritical carbon dioxide mixed with trioctylamine (TOA) at different temperatures. TOA was used as an (IPFR) ion-pair forming reagent for increasing the extraction efficiency of ScCO2 method. They found that the extracted acids amount was decreased with decreasing temperature.14 Another method for the separation of maleic acid was an adsorption method by Chollier et al.15 Platinium catalyst was used to adsorp maleic acid from water. In this study, citric acid extraction with TOPO and DOA in alcohol, alkane, and ketone, which has not been studied up to now, was discussed. Maleic acid and citric acid were chosen according to their acidic properties. Maleic acid has two carboxylic groups and citric acid has three carboxyclic groups. A comparison of the acids from different extractants using many diluents was the aim of this work.

3. RESULTS AND DISCUSSION 3.1. Physical Extraction Results. The physical extraction experiments were performed with diluents (1-butanol, isobutyl methyl ketone, ethyl methyl ketone, isoamyl alcohol, diisobutyl ketone, n-octane, 1-octanol, n-decane, 1-decanol) for better understanding of the effect of TOPO and DOA to the extraction of citric and maleic acids. The results were evaluated according to the KD values that were given below in Figure 1 and presented in Table 2 as the raw amine concentration is 0. Among the solvents used in this study, the highest distribution coefficient for citric acid was obtained with MEK (0.554) and the lowest with n-octane (0.006). The highest distribution coefficient for maleic acid was obtained with 1butanol (0.898) and the lowest also with n-octane (0.016). As seen from the results given in the tables, all pure solvents gave poor distrubution coefficients with respect to the mixtures used in reactive extraction experiments. 3.2. Reactive Extraction Results. i. Distribution Coefficients. Distribution coefficient (KD) of acids by TOPO and DOA can be expressed by a ratio of the total molality of acid in the organic phase mHA,aq to the aqueous phase mHA,org at equilibrium.

2. EXPERIMENTAL SECTION 2.1. Materials. Tri-n-octylphosphine oxide (≥99 purity), dioctylamine (≥99 purity), and maleic acid (≥99 purity), were purchased from Acros Organics. Citric acid (≥99 purity), 1butanol (≥99,5 purity), isobutyl methyl ketone (≥99 purity), ethyl methyl ketone (≥99 purity), isoamyl alcohol (≥98 purity), diisobutyl ketone (≥96 purity), n-octane (≥99 purity), 1-octanol (≥99 purity), n-decane (≥94 purity), 1-decanol (≥99 purity) were purchased from Merck. All chemicals were used without further purification, and Table 1 shows the physical properties of chemicals used in this study. The densities of pure liquids were used to estimate densities of the equilibrium phases and the mutual solubility of solvents and water. B



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> diethyl sebacate > diisobutyl ketone >1-butanol > isoamyl alcohol >1-decanol >1-octanol. For maleic acid extraction with TOPO−diluent system: isobutyl methyl ketone > diisobutyl ketone > ethyl methyl ketone > n-decane > diethyl sebacate > n-octane >1-butanol > isoamyl alcohol >1-decanol >1-octanol. For citric acid extraction with DOA−diluent system: isobutyl methyl ketone > diisobutyl ketone >1-octanol >1-decanol > isoamyl alcohol >1-butanol > diethyl sebacate > ethyl methyl ketone > n-decane > n-octane. For maleic acid extraction with DOA−diluent system: diisobutyl ketone > diethyl sebacate > ethyl methyl ketone > isobutyl methyl ketone > isoamyl alcohol >1-octanol > n-octane >1-decanol > n-decane >1butanol. The evaluation of KD values between physical extraction and reactive extraction of citric acid and maleic acid shows that the addition of TOPO and DOA to the organic phase significantly improves the KD values. For citric acid extraction with TOPO diluted in ethyl methyl ketone, the KD value increases up to 3.194 times larger than that attained with pure solvent, and for maleic acid extraction with TOPO diluted in methyl isobutyl ketone the KD value increases up to 15.3 times larger than that attained with pure solvent. Comparison of the KD values achieved using DOA in the organic phase to the ones achieved with only pure solvent reveals that for citric acid extraction with DOA diluted in methyl isubutyl ketone the KD value increases up to 55.44 times larger than that attained with pure solvent, and for maleic acid extraction with DOA diluted in diisobutyl ketone the KD value increases up to 164 times larger than that attained with pure solvent. ii. Extraction Yield. Extraction yield (%E) can be defined by using distribution coefficient (KD):

Figure 1. Distribution coefficients (KD) between water and pure solvents.

Molalities of the chemicals in mixed phases have been calculated by the following equations: morg:(HA) =

nHA,org Vorg ·ρorg − nHA,org ·MHA − n(TOPOorDOA),org ·M TOPOorDOA

(1)

morg(TOPOorDOA) =

norg,(TOPOorDOA) Vorg · ρorg − nHA,org ·MHA − n(TOPOorDOA),org ·M TOPOorDOA (2)

maq(HA) =

KD =

naq,(HA) Vaq ·ρaq − nHA,aq ·MHA

(3)

mHA,aq mHA,org

(4)

%E =

The reactive extraction of citric acid and maleic acid with TOPO and DOA diluted in nine different solvents (1-butanol, isobutyl methyl ketone, ethyl methyl ketone, isoamyl alcohol, diisobutyl ketone, n-octane, 1-octanol, n-decane, 1-decanol) was investigated. The organic phase TOPO concentration was changed from 0.229 mol·kg−1 to 2.74 mol·kg−1 using various diluents. However, the organic phase DOA concentration was changed from 0.303 mol·kg−1 to 1.707 mol·kg−1 diluted in the same solvents. The initial aqueous citric acid and maleic acid concentrations were 0.453 mol·kg−1 and 0.749 mol·kg−1, respectively. The data for the distribution of citric acid and maleic acid between water and TOPO or DOA dissolved in various diluents are shown in Tables 2 to 5 and are illustrated in Figure 2a−d. The maximum extracted citric acid (KD: 122.582) was achieved with 1.639 mol·kg−1 DOA dissolved in isobutyl methyl ketone which was higher than that for all other diluents. The maximum extracted maleic acid (KD: 168.187) was achieved with 1.662 mol·kg−1 DOA dissolved in diisobutyl ketone which was higher than that for all other diluents. The results show that that KD increases with an increase in the initial amount of TOPO and DOA in the organic phase. Besides recovery of these acids by reactive extraction considerably enhances the distribution coefficients of the extraction process instead of the ones attained in physical extraction. The KD values for the reactive extraction of citric acid and maleic acid by TOPO and DOA diluted with different solvents were found in the following order: For citric acid extraction with TOPO−diluent system: ethyl methyl ketone > isobutyl methyl ketone > n-octane > n-decane

KD × 100 1 + KD

(5)

An examination of the data found in Tables 2 and 3 shows that the extraction efficiency of citric acid varies in the range of 0.81−67.12% according to the diluents used and the maximum extracted citric acid can be achieved by TOPO (2.07 mol·kg−1) diluted in ethyl methyl ketone as 67.12%. For the maleic acid when TOPO diluted by methyl isobutyl ketone (2.064 mol· kg−1) used, these values are 16.25−89.33% for the extraction interval and 89.33% for the maximum extraction efficiency (Figure 3). An examination of the data found in Tables 4 and 5 shows that the extraction efficiency of citric acid varies in the range of 13.95−99.19% according to the diluents used, and the maximum extracted citric acid can be achieved by DOA (1.639 mol·kg−1) diluted in isobutyl methyl ketone as 99.19%. For the maleic acid when DOA is diluted by diisobutyl ketone (1.662 mol·kg−1), these values are 31.94−99.41% for the extraction interval and 99.41% for the maximum extraction efficiency. It can be clearly understood from the experimental results that DOA is a very effective extractant for these acids and the increase in TOPO and DOA concentration results in a regular increase in extraction efficiency. iii. Loading Ratio. Loading ratio can be defined as the ratio between acid concentration in the organic phase and DOA or TOPO concentration in the organic phase.2,9 Z= C

mHA,org m TOPO

or

Z=

mHA,org mDOA

(6) DOI: 10.1021/acs.jced.7b00562 J. Chem. Eng. Data XXXX, XXX, XXX−XXX


Article

Table 2. Citric Acid Extraction Results with TOPO + Diluent System at T = 298.5 K and P = 1.01332 bara diluent butanol

decanol

isoamyl alcohol

methyl isobutyl ketone

octanol

octane

decane

diisobutyl ketone

ethyl methyl ketone

mTOPO.(org) (mol·kg−1)

mHA.(aq) (mol·kg−1)

mHA.(org) (mol·kg−1)

D

Z

%E

0.23 0.515 0.885 1.372 2.034 0 0.233 0.515 0.886 1.378 2.044 0 0.228 0.516 0.883 1.378 2.058 0 0.23 0.515 0.893 1.369 2.053 0 0.233 0.521 0.891 1.385 2.046 0 0.232 0.515 0.885 1.375 2.067 0 0.236 0.514 0.88 1.373 2.061 0 0.232 0.519 0.886 1.379 2.074 0 0.229 0.525 0.881 1.373 2.07 0

0.374 0.395 0.374 0.365 0.345 0.368 0.445 0.445 0.439 0.419 0.378 0.447 0.449 0.439 0.409 0.399 0.369 0.443 0.414 0.341 0.301 0.219 0.186 0.444 0.432 0.451 0.45 0.415 0.383 0.448 0.419 0.363 0.332 0.24 0.189 0.45 0.419 0.366 0.301 0.269 0.192 0.442 0.437 0.363 0.282 0.234 0.199 0.448 0.276 0.258 0.212 0.168 0.149 0.292

0.079 0.058 0.079 0.088 0.108 0.085 0.008 0.008 0.014 0.034 0.075 0.005 0.006 0.014 0.044 0.054 0.084 0.009 0.039 0.112 0.152 0.234 0.267 0.009 0.021 0.001 0.003 0.038 0.07 0.005 0.034 0.09 0.121 0.213 0.264 0.002 0.034 0.087 0.152 0.184 0.261 0.011 0.016 0.09 0.171 0.219 0.254 0.005 0.177 0.195 0.241 0.285 0.304 0.161

0.21 0.145 0.211 0.241 0.314 0.23 0.017 0.019 0.033 0.082 0.199 0.013 0.008 0.032 0.107 0.135 0.227 0.022 0.093 0.329 0.503 1.066 1.433 0.021 0.049 0.003 0.007 0.091 0.182 0.012 0.082 0.249 0.366 0.886 1.399 0.006 0.081 0.237 0.505 0.683 1.363 0.024 0.037 0.247 0.604 0.933 1.276 0.012 0.639 0.754 1.138 1.697 2.041 0.554

0.343 0.112 0.089 0.064 0.053

17.39 12.8 17.41 19.44 23.91 18.72 1.69 1.86 3.17 7.55 16.56 1.25 0.81 3.15 9.64 11.88 18.51 2.18 8.55 24.74 33.47 51.59 58.9 2.06 4.69 0.33 0.66 8.35 15.38 1.15 7.55 19.92 26.81 46.99 58.32 0.61 7.47 19.13 33.54 40.58 57.69 2.35 3.6 19.82 37.66 48.27 56.05 1.16 38.98 42.99 53.23 62.92 67.12 35.65

0.033 0.016 0.016 0.025 0.037 0.016 0.028 0.049 0.039 0.041 0.168 0.218 0.17 0.171 0.13 0.091 0.003 0.003 0.027 0.034 0.148 0.175 0.137 0.155 0.128 0.144 0.168 0.173 0.134 0.127 0 0.07 0.173 0.193 0.159 0.122 0 0.77 0.371 0.274 0.208 0.147 0

a

mTOPO.(org) is the molality of topo in the organic phase; mHA.(aq) is the molalitiy of acid in the aqueous phase; mHA.(org) is the molality of the acid in the organic phase; D is the distribution coefficient; Z is the loading factor; %E is the extraction efficiency. Standard uncertainties u are u(T) = 1 K, u(P) = 1 kPa, u(mTOPO(org)) = 0.07 mTOPO(org), u(mHA(aq)) = 0.03mHA(aq), and u(mHA(org)) = 0.01 mol·kg−1. Solvent: organic diluent + water. D



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Table 3. Maleic Acid Extraction Results with TOPO + Diluent System at T = 298.5 K and P = 1.01332 bara diluent butanol

decanol

isoamyl alcohol


octanol

octane

decane

diisobutyl ketone

ethyl methyl ketone

mTOPO.(org) (mol·kg−1)

mHA.(aq) (mol·kg−1)

mHA.(org) (mol·kg−1)

D

Z

%E

0.229 0.516 0.883 1.377 2.057 0 0.236 0.518 0.888 1.376 2.059 0 0.239 0.514 0.883 1.382 2.063 0 0.228 0.518 0.881 1.372 2.064 0 0.229 0.525 0.895 1.377 2.062 0 0.233 0.521 0.884 1.376 2.062 0 0.235 0.516 0.888 1.377 2.073 0 0.228 0.52 0.885 1.382 2.071 0 0.228 0.516 0.88 1.382 2.058 0

0.415 0.397 0.395 0.388 0.333 0.395 0.627 0.589 0.516 0.444 0.345 0.674 0.455 0.416 0.398 0.386 0.34 0.484 0.484 0.347 0.257 0.193 0.08 0.586 0.598 0.536 0.506 0.435 0.367 0.637 0.611 0.506 0.378 0.262 0.191 0.737 0.611 0.506 0.367 0.275 0.164 0.7 0.567 0.481 0.309 0.214 0.148 0.73 0.364 0.311 0.254 0.209 0.157 0.403

0.334 0.352 0.354 0.361 0.416 0.354 0.122 0.16 0.233 0.305 0.404 0.075 0.294 0.333 0.351 0.363 0.409 0.265 0.265 0.402 0.492 0.556 0.669 0.163 0.151 0.213 0.243 0.314 0.382 0.112 0.138 0.243 0.371 0.487 0.558 0.012 0.138 0.243 0.382 0.474 0.585 0.049 0.182 0.268 0.44 0.535 0.601 0.019 0.385 0.438 0.495 0.54 0.592 0.346

0.804 0.888 0.894 0.931 1.249 0.898 0.194 0.271 0.45 0.686 1.17 0.111 0.645 0.801 0.884 0.943 1.204 0.548 0.547 1.16 1.909 2.88 8.369 0.277 0.253 0.397 0.481 0.72 1.043 0.176 0.227 0.481 0.982 1.861 2.919 0.016 0.225 0.48 1.042 1.729 3.574 0.07 0.321 0.558 1.424 2.495 4.062 0.027 1.055 1.41 1.949 2.583 3.765 0.858

0.647 1.537 0.257 0.409 0.202 0 0.516 0.308 0.262 0.222 0.196 0 0.332 0.647 1.473 0.263 0.198 0 1.162 0.777 0.558 0.405 0.324 0 0.659 0.406 0.272 0.228 0.185 0 0.593 0.467 0.42 0.354 0.271 0 0.585 0.471 0.431 0.345 0.282 0 0.8 0.516 0.497 0.387 0.29 0 1.683 0.85 0.562 0.391 0.288 0

44.56 47.05 47.21 48.22 55.53 47.31 16.25 21.3 31.06 40.7 53.91 10.03 39.2 44.46 46.92 48.52 54.63 35.42 35.37 53.71 65.62 74.23 89.33 21.71 20.17 28.43 32.48 41.86 51.05 14.99 18.48 32.48 49.54 65.04 74.49 1.61 18.37 32.44 51.02 63.35 78.13 6.54 24.32 35.81 58.74 71.39 80.25 2.6 51.34 58.5 66.09 72.09 79.01 46.17

a

mTOPO.(org) is the molality of TOPO in the organic phase; mHA.(aq) is the molalitiy of acid in the aqueous phase; mHA.(org) is the molality of the acid in the organic phase; D is the distribution coefficient; Z is the loading factor; %E is the extraction efficiency. Standard uncertainties u are u(T) = 1 K, u(P) = 1 kPa, u(mTOPO(org)) = 0.07 mTOPO(org), u(mHA(aq)) = 0.03mHA(aq), and u(mHA(org)) = 0.01 mol·kg−1. Solvent: organic diluent + water. E



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Table 4. Citric Acid Extraction Results with DOA + Diluent System at T = 298.5 K and P = 1.01332 bara diluent butanol

decanol

isoamyl alcohol


octanol

octane

decane

diisobutyl ketone

ethyl methyl ketone

mDOA,(org) (mol·kg−1)

mHA,(aq) (mol·kg−1)

mHA,(org) (mol·kg−1)

D

Z

%E

0.352 0.668 0.993 1.327 1.668 0 0.35 0.66 0.971 1.237 1.621 0 0.335 0.686 0.993 1.346 1.648 0 0.341 0.673 0.993 1.335 1.639 0 0.384 0.674 0.994 1.293 1.626 0 0.317 0.673 0.985 1.32 1.628 0 0.347 0.663 0.992 1.282 1.632 0 0.335 0.668 0.982 1.355 1.707 0 0.303 0.673 0.987 1.331 1.651 0

0.104 0.026 0.011 0.012 0.006 0.368 0.208 0.053 0.011 0.008 0.005 0.447 0.149 0.028 0.012 0.009 0.005 0.443 0.141 0.103 0.01 0.006 0.004 0.444 0.16 0.032 0.015 0.01 0.005 0.448 0.39 0.196 0.036 0.013 0.011 0.45 0.115 0.03 0.02 0.016 0.011 0.442 0.14 0.024 0.011 0.008 0.005 0.448 0.155 0.025 0.012 0.011 0.008 0.292

0.349 0.427 0.442 0.441 0.447 0.085 0.245 0.4 0.442 0.445 0.448 0.006 0.304 0.425 0.441 0.444 0.448 0.01 0.312 0.35 0.443 0.447 0.449 0.009 0.293 0.421 0.438 0.443 0.448 0.005 0.063 0.257 0.417 0.44 0.442 0.003 0.338 0.423 0.433 0.437 0.442 0.011 0.313 0.429 0.442 0.445 0.448 0.005 0.298 0.428 0.441 0.442 0.445 0.161

3.367 16.58 39.003 37.305 80.453 0.23 1.178 7.585 41.721 57.35 88.607 0.013 2.047 15.221 37.644 51.461 81.812 0.022 2.211 3.415 44.304 71.846 122.582 0.021 1.825 13.13 28.267 44.439 96.081 0.012 0.162 1.306 11.532 33.703 40.362 0.006 2.924 13.862 22.21 27.225 41.042 0.024 2.238 17.788 41.382 54.179 91.325 0.012 1.922 17.259 36.15 41.042 56.444 0.554

0.991 0.64 0.445 0.332 0.268 0 0.701 0.606 0.456 0.36 0.276 0 0.909 0.62 0.444 0.33 0.272 0 0.915 0.521 0.446 0.335 0.274 0 0.763 0.624 0.44 0.343 0.276 0 0.199 0.381 0.423 0.333 0.272 0 0.974 0.638 0.437 0.341 0.271 0 0.934 0.642 0.451 0.328 0.262 0 0.983 0.636 0.447 0.332 0.27 0

77.1 94.31 97.5 97.39 98.77 18.72 54.09 88.35 97.66 98.29 98.88 1.25 67.18 93.84 97.41 98.09 98.79 2.18 68.85 77.35 97.79 98.63 99.19 2.06 64.6 92.92 96.58 97.8 98.97 1.15 13.95 56.63 92.02 97.12 97.58 0.61 74.51 93.27 95.69 96.46 97.62 2.35 69.11 94.68 97.64 98.19 98.92 1.16 65.78 94.52 97.31 97.62 98.26 35.65

a

mTOPO.(org) is the molality of TOPO in the organic phase; mHA.(aq) is the molalitiy of acid in the aqueous phase; mHA.(org) is the molality of the acid in the organic phase; D is the distribution coefficient; Z is the loading factor; %E is the extraction efficiency. Standard uncertainties u are u(T) = 1 K, u(P) = 1 kPa, u(mTOPO(org)) = 0.07 mTOPO(org), u(mHA(aq)) = 0.03mHA(aq), and u(mHA(org)) = 0.01 mol·kg−1. Solvent: organic diluent + water. F



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Table 5. Maleic Acid Extraction Results with DOA + Diluent System at T = 298.5 K and P = 1.01332 bara diluent butanol

decanol

isoamyl alcohol


octanol

octane

decane

diisobutyl ketone

ethyl methyl ketone

mDOA,(org) (mol·kg−1)

mHA,(aq) (mol·kg−1)

mHA,(org) (mol·kg−1)

D

Z

%E

0.369 0.666 1.003 1.327 1.628 0 0.359 0.669 1.008 1.307 1.635 0 0.34 0.669 1.006 1.287 1.64 0 0.335 0.676 1.001 1.327 1.643 0 0.347 0.693 0.994 1.316 1.625 0 0.335 0.681 0.974 1.359 1.657 0 0.331 0.681 1.029 1.324 1.657 0 0.343 0.663 1.006 1.339 1.662 0 0.307 0.632 1.006 1.286 1.63 0

0.219 0.039 0.028 0.014 0.019 0.395 0.298 0.029 0.017 0.013 0.009 0.674 0.353 0.025 0.015 0.011 0.007 0.48 0.247 0.028 0.017 0.013 0.007 0.586 0.29 0.022 0.013 0.018 0.009 0.637 0.406 0.134 0.014 0.014 0.009 0.737 0.51 0.119 0.023 0.018 0.014 0.7 0.37 0.044 0.018 0.009 0.004 0.718 0.186 0.047 0.01 0.009 0.007 0.403

0.53 0.71 0.721 0.735 0.73 0.354 0.451 0.72 0.732 0.736 0.74 0.075 0.396 0.724 0.734 0.738 0.742 0.269 0.502 0.721 0.732 0.736 0.742 0.163 0.459 0.727 0.736 0.731 0.74 0.112 0.343 0.615 0.735 0.735 0.74 0.012 0.239 0.63 0.726 0.731 0.735 0.049 0.379 0.705 0.731 0.74 0.745 0.031 0.563 0.702 0.739 0.74 0.742 0.346

2.42 18.013 25.378 51.343 37.861 0.898 1.513 25.021 42.73 57.834 83.55 0.111 1.121 28.445 48.722 67.322 102.275 0.561 2.036 25.544 43.553 55.463 113.51 0.277 1.581 33.367 54.714 41.232 85.797 0.176 0.847 4.595 53.84 51.343 84.299 0.016 0.469 5.308 31.869 39.734 52.841 0.07 1.025 15.99 40.857 84.299 168.187 0.044 3.026 14.963 75.311 78.307 108.267 0.858

1.435 1.066 0.719 0.554 0.448 0 1.257 1.077 0.726 0.563 0.453 0 1.164 1.081 0.73 0.574 0.452 0 1.497 1.066 0.731 0.554 0.452 0 1.321 1.049 0.74 0.556 0.456 0 1.024 0.903 0.755 0.541 0.447 0 0.722 0.925 0.706 0.552 0.444 0 1.104 1.064 0.726 0.553 0.448 0 1.832 1.111 0.735 0.575 0.455 0

70.76 94.74 96.21 98.09 97.43 47.31 60.2 96.16 97.71 98.3 98.82 10.03 52.84 96.6 97.99 98.54 99.03 35.93 67.06 96.23 97.76 98.23 99.13 21.71 61.26 97.09 98.21 97.63 98.85 14.99 45.84 82.13 98.18 98.09 98.83 1.61 31.94 84.15 96.96 97.55 98.14 6.54 50.61 94.11 97.61 98.83 99.41 4.2 75.16 93.74 98.69 98.74 99.08 46.17

a

mDOA.(org) is the molality of TOPO in the organic phase; mHA.(aq) is the molalitiy of acid in the aqueous phase; mHA.(org) is the molality of the acid in the organic phase; D is the distribution coefficient; Z is the loading factor; %E is the extraction efficiency. Standard uncertainties u are u(T) = 1 K, u(P) = 1 kPa, u(mTOPO(org)) = 0.07 mTOPO(org), u(mHA(aq)) = 0.03mHA(aq), and u(mHA(org)) = 0.01 mol·kg−1. Solvent: organic diluent + water. G



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Figure 2. (a) Variation of distribution coefficients for (a) citric acid with TOPO concentration in different solvents; (b) maleic acid with TOPO concentration in different solvents; (c) citric acid with DOA concentration in different solvents; (d) maleic acid with DOA concentration in different solvents.

TOPO and DOA diluted in different solvents was investigated. The results were evaluated on the basis of distribution coefficients, extraction efficiencies, and loading ratios. The following conclusions can be drawn: According to the results of physical and reactive extraction, the use of extractants such as TOPO and DOA significantly enhances the extraction of citric and maleic acids from their aqueous solutions. The use of amine based extractant, DOA, shows considerably better results than the phosphorus-based extractant, TOPO, in both citric acid and maleic acid extraction processes despite having some issues in the separation step. The maximum extracted citric acid (KD: 122.582) was achieved with 1.639 mol·kg−1 DOA dissolved in isobutyl methyl ketone with an extraction efficiency of 99.19% and the maximum extracted maleic acid (KD: 168.187) was achieved with 1.662 mol·kg−1 DOA dissolved in diisobutyl ketone with an extraction efficiency of 99.41%. The results show that that KD and extraction efficiency increases with an increase in the initial amount of TOPO and DOA in the organic phase. The DOA + isobutyl methyl ketone system and the DOA + disobutyl ketone system in the organic phase is recommended for the citric acid and maleic acid extraction processes respectively. It is concluded that the use of solvents may serve individually as adequate materials to extract the citric and maleic acid from their dilute aqueous solutions; however, the extraction performance can be enhanced considerably by using

The effect of TOPO concentration on loading, Z, is shown in Tables 2 and 3 and the effect of DOA concentration on loading is shown in Tables 4 and 5. Overloading (loading greater than unity) indicates that complexes with more than one acid molecule per TOPO or DOA molecule have been formed. Interpreting these values briefly shows us that for citric extraction with TOPO diluted in a solvent, the loading ratio is lower than unity in all cases, so overloading is not expected. For maleic extraction with TOPO diluted in a solvent, the loading ratio is lower than unity in almost all cases except for only one specimen in each TOPO with butanol, isoamyl alcohol, isobutyl methyl ketone, and ethyl methyl ketone organic phase. Extraction of maleic acid using DOA diluted with a solvent in the organic phase shows Z values bigger than unity at low concentrations of DOA, but overloading is eliminated when the DOA concentration increases in organic phase. In citric acid extraction with DOA, almost in all specimens Z values were smaller than unity, so overloading was not observed. The loading curve is a plot of Z versus extractant concentration. In Figure 4a−d the effect of TOPO and DOA concentration on loading is shown, respectively. As shown in the panels of the Figure 4 loading ratio decreases with increasing amine concentration.

4. CONCLUSIONS In this study in addition to the physical extraction experiments, the reactive extraction of citric acid and maleic acid with H



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Figure 3. Variation of extraction efficiency for (a) citric acid with TOPO concentrations; (b) maleic acid with TOPO concentration; (c) citric acid with DOA concentration; (d) maleic acid with DOA concentration. (6) Dai, Y.; King, C. J. Selectivity between lactic acid and glucose during recovery of lactic acid with basic extractants and polymeric sorbents. Ind. Eng. Chem. Res. 1996, 35, 1215−1224. (7) Husson, S. M.; King, C. J. Multiple-acid equilibria in adsorption of carboxylic acids from dilute aqueous solution. Ind. Eng. Chem. Res. 1999, 38, 502−511. (8) Lee, E. G.; Moon, S. H.; Chang, Y. K. Lactic acid recovery using two-stage electrodialysis and its modelling. J. Membr. Sci. 1998, 145, 53−66. (9) Thakre, N.; Prajapati, A. K.; Mahapatra, S. P.; Kumar, A.; Khapre, A.; Pal, D. Modeling and Optimization of Reactive Extraction of Citric Acid. J. Chem. Eng. Data 2016, 61, 2614−2623. (10) Chanukya, B. S.; Prakash, M.; Rastogi, N. K. Extraction of Citric Acid from Fruit Juices using Supported Liquid Membrane. J. Food Process. Preserv. 2017, 41, 1745−4549. (11) Djas, M.; Henczka, M. Reactive extraction of citric acid using supercritical carbon dioxide. J. Supercrit. Fluids 2016, 117, 59−63. (12) Rani, K. N. P.; Kumar, T. P.; Murthy, J. S. N.; Sankarshana, T.; Vishwanadham, B. Equilibria, Kinetics, and Modeling of Extraction of Citric Acid from Aqueous Solutions with Alamine 336 in 1-Octanol. Sep. Sci. Technol. 2010, 45, 654−662. (13) Bayazit, S. S.; Uslu, H.; Inci, I. Comparative Equilibrium Studies for Citric Acid by Amberlite LA-2 or Tridodecylamine (TDA). J. Chem. Eng. Data 2009, 54, 1991−1996. (14) Rahmanian, A.; Ghaziaskar, H. S. Selective extraction of maleic acid and phthalic acid by supercritical carbon dioxide saturated with trioctylamine. J. Supercrit. Fluids 2008, 46, 118−122. (15) Chollier, M. J.; Epron, F.; Lamy-Pitara, E.; Barbier, J. Study of the adsorption of maleic acid on platinum by electrochemical methods. J. Chim. Phys. Phys.-Chim. Biol. 1997, 94, 2027−2036. (16) Smallwood, I. M. Handbook of Organic Solvent Properties; John Wiley&Sons Inc.: New York, 1996.

phosphorus or amine based extractants such as TOPO or DOA.

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. ORCID

Hasan Uslu: 0000-0002-4985-7246 Funding

This work was supported by Scientific Research Project Coordination Unit of Istanbul University. Project No. 22274 Notes

The authors declare no competing financial interest.

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REFERENCES

(1) Oasmaa, A.; Kuoppala, E.; Gust, S.; Solantausta, Y. Fast Pyrolysis of Forestry Residue. 1. Effect of Extractives on Phase Separation of Pyrolysis Liquids. Energy Fuels 2003, 17, 1−12. (2) Hatti-Kaul, R.; Törnvall, U.; Gustafsson, L.; Börjesson, P. Industrial Biotechnology for the Production of Bio-Based Chemicals − A Cradle-to-Grave Perspective. Trends Biotechnol. 2007, 25, 119− 124. (3) Buchard, E. F.; Merrit, E. G. Citric Acid” In “Kirk-Othmers Encyclopedia Of Chemical Technology, 3rd ed.;Wiley: New York, 1979; Vol. 6, pp 150. (4) Schügerl, K. Integrating processing of biotechnology products. Biotechnol. Adv. 2000, 18, 581−599. (5) Tung, L. A.; King, C. J. Sorption and extraction of lactic and succinic acids at pH > pKa1. 1. Factors Governing Equilibria. Ind. Eng. Chem. Res. 1994, 33, 3217−3223. I



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Figure 4. Variation of loading factor for (a) citric acid with TOPO concentration; (b) maleic acid with TOPO concentration; (c) citric acid with DOA concentration; (d) maleic acid with DOA concentration. (17) Cheremisinoff, N. P. Industrial Solvents Handbook, 2nd ed.; Marcel Dekker Inc.: New York, 2003. (18) Apelblat, A. Citric Acid; Springer International Publishing: Switzerland, 2014. (19) Wongkaew.; et al. The Solubility of Maleic Acid in Various Inorganic Salts and Organic Solvents: Thermodynamics Model and Paremeters,. Fluid Phase Equilib. 2017, 450, 75−85.

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Extraction of Citric Acid and Maleic Acid from Their Aqueous Solutions

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