Ultrasound Assisted Hydrotropic Extraction: A Greener Approach for

Subscriber access provided by READING UNIV

Article

Ultrasound Assisted Hydrotropic Extraction: A Greener Approach for the Isolation of Geraniol from the Leaves of Cymbopogon martinii Miral R. Thakker, Jigisha K. Parikh, and Meghal A Desai ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/ acssuschemeng.7b03374 • Publication Date (Web): 15 Jan 2018 Downloaded from http://pubs.acs.org on January 15, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

ACS Sustainable Chemistry & Engineering is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 41 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Sustainable Chemistry & Engineering

Ultrasound Assisted Hydrotropic Extraction: A Greener Approach for the Isolation of Geraniol from the Leaves of Cymbopogon martinii Miral R. Thakker1,2, Jigisha K. Parikh2 and Meghal A. Desai2* 1

Chemical Engineering Department, Pacific School of Engineering, Palsana, Surat-394305, Gujarat, India.

2

Chemical Engineering Department, Sardar Vallabhbhai National Institute of Technology, Surat395007, Gujarat, India

Abstract

Geraniol, a prime constituent in the leaves of Cymbopogon martinii, has the varied range of biological activities and applications. For the selective isolation of geraniol, a newer concept of

*

Address to whom correspondence should be made

desai_ma @yahoo.co.in, [email protected] Tel: 91-261-2201709, 2201641; Fax: 91-261-2201641

ACS Paragon Plus Environment

1

ACS Sustainable Chemistry & Engineering 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 41

combining hydrotropic extraction with ultrasound was adopted to reduce the time of extraction and hydrotrope requirement while maintaining the quality of the product. Sodium cumene sulfonate was selected as a suitable hydrotrope amongst sodium cumene sulfonate, sodium salicylate, sodium salt of para toluene sulfonic acid and resorcinol using the solubilization study. The screening of extraction parameters viz., ultrasound amplitude, cycle time, volume of hydrotropic solution, hydrotropic concentration, ultrasonic power and sonication time was carried out using the Taguchi method. Optimization of process parameters was performed using central composite response surface design. 1.9012 % (w/w) yield of geraniol was obtained under optimized conditions (65 % ultrasound amplitude, 65 mL volume of 1 M aqueous solution of sodium cumene sulfonate, 60 W ultrasound power, 70 % cycle time and 16 min of sonication time). A microscopic study was also performed to understand the extraction mechanism. Ultrasound assisted hydrotropic extraction turned out to be a superior sustainable alternative compared to the hydrotropic extraction because of shortening of extraction time and reduction in hydrotrope concentration.

Key words: Geraniol, Hydrotropes, Microscopy, Response surface methodology, Taguchi method, Ultrasound.

INTRODUCTION A recent trend in modern society is “Green consumerism”, which requires few synthetic substances in food, flavor and perfume industry. Due to increased inclination towards sustainable development and green concepts, extraction of naturally occurring products has increased. The


2

Page 3 of 41 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


chemicals derived from the plants are considered as “GRAS – generally recognized as safe” and thus they can widely be used commercially in food, flavor and fragrance industry

1,2

.

Cymbopogon martinii, commonly known as palmarosa, is a perennial aromatic grass of Indian origin. The oil extracted from palmarosa is universally known as palmarosa oil, having geraniol and geranyl acetate as the major constituents 3. Geraniol, a terpene alcohol, is commonly known for a wide spectrum of pharmacological and biological activities such as antifungal

4

,

antimicrobial 4, anti-helminthic 5 and plant based insect repellent 6. Geraniol has been found to exhibit antiproliferative properties against malignant cells 7. It is an exhaustively used compound in toiletries, flavor and fragrance industries 7,8 and, therefore, its consumption is more than 1000 metric tonnes per annum 8. Since the oil composition is affected by the harvesting time and season, the suitability of harvesting time and effect of climatic conditions were studied by Smitha and Rana 9, and Kakaraparthi et al.

10.

A minor variation in the geraniol content was

observed (83.58 % against 88.21 %) for harvesting in different seasons (April – May, 2013 against September – October, 2013) 9. This was possible if harvesting time could be selected in a proper manner. Similar results have been observed while harvesting the leaves in the months of October – December, 2012 (76.9 %) and January – March, 2013 (78.3 %) 10. Thus, the geraniol content can be kept almost constant during different harvesting seasons. Conventionally palmarosa oil was extracted using the field distillation process 11 but no reports are available for isolating geraniol from the leaves. Though simple, this method is laborious, time consuming and energy inefficient 12. Moreover, post processing treatment forms the integral part for purifying geraniol which in turn makes the operation more tedious and increases energy burden. In order to overcome environmental and energy issue along with the mentioned one for conventional method, the concept of green chemistry and eco-extraction has emerged


13-15

.

3


Chemat et al.

13

Page 4 of 41

have introduced the term green extraction and laid six principles to follow. The

main goals of these movements are to reduce the burden on the environment and make the process energy efficient 13,14. During the past decades, hydrotropes have been extensively used in the areas of extraction of various phytochemicals, distillation, microemulsion formulation and drug formulation

16-22

. The extraction process using hydrotrope can be considered as a green

extraction because they are chemically inert, easily separable, readily reusable and selective towards the targeted compounds

16-25

. However this method suffers from the limitation of

extended extraction time and a higher concentration of hydrotrope

23

. These limit the wide

acceptance of hydrotropic extraction as an alternative to the conventional method for isolation of value added components from various plant materials. Ultrasound assisted extraction (UAE), a clean and green technology, was effectively implemented in natural product extraction due to obvious advantages like reduction of solvent volume, lessening the extraction time and improving the product quality along with reduced processing costs 15,26-31. Energy efficiency and environmentally benign nature are the key features of this method

15,26-31

. This is because low

frequency high intensity ultrasound waves induce acoustic cavitation which may lead to the destruction of cell walls and thereby releasing the active constituents

15,32

. Various bioactive

compounds from different plant materials have been successfully extracted using ultrasound assisted extraction

15,26-32

. The presence of organic solvents after purification is one of the

concerns in extraction using ultrasound.

Aiming towards incorporating the concept of value addition to the existing novel process and thereby achieving green and sustainable development, ultrasound treatment was engrained in hydrotropic extraction. It would be interesting to investigate the effect of sonication in


4

Page 5 of 41 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


hydrotropic solution since the solution has high viscosity and low surface tension. Further, addition of surfactant has altered the transformation of stable and transient bubbles which are responsible for acoustic phenomena. In case of non ionic surfactant, transient bubble formation appeared to be enhanced leading to improved cavitation

33

. This behavior can be expected for

hydrotropic solution because of similar nature and, therefore, increased penetration of hydrotropic solution in the cells should occur. Hence, a synergistic effect of sonication and hydrotropy can be expected on plant cells and intensification of the process may be achieved. Finally, ultrasound assisted hydrotropic extraction (UAHE) should provide integrity of positive features of both the techniques viz., selectivity, rapid recovery of solute and reusability of solvent, reduced solvent consumption and shortened extraction time. Based on these objectives, UAHE was employed for the isolation of geraniol from palmarosa leaves. Solubilization of geraniol in various hydrotropes namely, sodium cumene sulfonate (NaCuS), sodium salicylate (NaSal), sodium salt of para toluene sulfonic acid (Na-PTSA) and resorcinol was conducted for selecting the best hydrotrope amongst these for extraction purpose. The screening of process parameters affecting the performance of UAHE was initially done using the Taguchi method. Response surface methodology (RSM) was utilized to design mathematical model, study interaction effect and optimize process parameters. The technique was compared with hydrotropic extraction to appreciate the benefits of incorporating sonication. Energy and environmental aspects were also analyzed for the green and sustainable prospective of UAHE. The effect of extraction mechanism on the plant cell was analyzed using SEM.

MATERIALS AND METHODS Materials


5


Page 6 of 41

Leaves of Palmarosa were collected from Directorate of Medicinal and Aromatic Plants Research (DMAPR), Anand, India (22.5 °N latitude and 73.0 °E longitude) during November, 2016. The leaves, after drying under a shed for 72 h, were stored in a moisture-free environment at room temperature. Geraniol (99.9% pure) was purchased from Sigma Aldrich, Bangalore, India. Four hydrotropes viz., sodium cumene sulfonate (92 % pure, National Chemicals, Baroda, India), sodium salicylate (99 % pure, Finar Ltd., Ahmedabad, India), sodium salt of para toluene sulfonic acid (98 % pure, Loba Chemie Pvt. Ltd., Mumbai, India) and resorcinol (99 % pure, Loba Chemie Pvt. Ltd., Mumbai, India) were procured for solubilization and extraction purposes. Sodium cumene sulfonate was used after re-crystallization. Deionized water was used for preparation of aqueous solutions. Optimum particle size of the leaves, based on previous study, was kept at 280 µm 34. Hexane of HPLC and spectroscopy grade was procured from Finar Ltd., Ahmedabad, India.

Methods Solubility study Solubilization of geraniol in aqueous solution of NaCuS, NaSal, Na-PTSA and resorcinol in the concentration range of 0.2 – 2 M was performed for selecting the suitable hydrotrope for the extraction study. 0.5 mL geraniol was added in 1 mL hydrotropic solution, which was then agitated at high speed for rapid dissolution using cyclomixer (REMI CM 101 Plus, Mumbai, India) for 15 min at a room temperature. The hydrotropic solution was then partitioned with hexane (1 mL solution: 1.5 mL hexane) to determine the amount of geraniol dissolved in the hydrotropic solution.


6

Page 7 of 41 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Ultrasound assisted hydrotropic extraction (UAHE) For combining the sonication with hydrotropic extraction, ultrasonic processor (UP200Ht, Hielscher Ultrasonics GmbH Company, Germany; 26 kHz working frequency; 200 W power) having sonotrode of 7 mm diameter (S26d7) was used for sonication. The processor has three variables namely, power, amplitude and cycle time. A glass vessel of 100 mL capacity was employed as an extractor. The probe was kept in the extraction vessel with 2 cm immersion depth. The plant material along with the hydrotropic solution was subjected to sonication for extraction of geraniol. In the present study, solid loading was kept constant at 2 g since an increased solid content has resulted in slurry formation creating difficulty in cavitation and, thereby, deterring the mass transfer and finally, poor extraction. Also, filtration has become very difficult and loss of hydrotropic solution was observed. The volume of the solution was varied in the range of 40 – 80 mL while concentration was kept in the range of 0.2 – 1.8 M for studying their impact on the geraniol recovery. Extraction time was varied from 4 to 20 min. Each experiment was performed at least twice. Upon completion of extraction, the mixture was filtered using the WhatmanTM filter paper (110 mm ø, cat number: 1001-110). Since the solid loading was less which may pose difficulty in recovering the solute by mere dilution, partitioning using hexane has been carried out. From the collected filtrate, 1 mL was then partitioned with 1 mL hexane for 30 min and then analyzed using gas chromatography (GC). The lean aqueous solution obtained after partitioning was again contacted with fresh hexane (1 mL) for examining possible presence of geraniol, however, no traces of geraniol were found.

Screening of parameters using the Taguchi method


7


Page 8 of 41

For optimization of 5 or more variables, it is advisable to perform screening study to identify the influential parameters which can be optimized 35. In the present study, the Taguchi method, a fractional factorial design, is employed for screening purpose, since it is based on an orthogonal array, i.e., the design is balanced and each factor is given equal weightage. This leads to independent evaluation of each factor without getting influenced by other factors. Based on the obtained responses, signal-to-noise (S/N) ratio is computed (either for the maximization of a response, minimization of a response or to achieve the target value). S/N ratio combines the number of repetitions into a single value presenting a variation in the results. To observe the impact of variation due to individual parameter, level total S/N ratio or its mean is computed based on individual S/N ratio for each factor at each level

22,36,37

. A variation in the level total

S/N ratio or its mean depends upon the yield of the geraniol which in turn is affected by changes introduced in the system by varying various parameters. Thus, the parameters for which larger variations in level total S/N ratio or its mean are observed can be considered to be the influencing one and should be included for optimization. Six factors viz., ultrasound amplitude, cycle time, volume of hydrotropic solution, hydrotropic concentration, ultrasonic power and sonication time were selected, which could influence the extraction of geraniol. Experimental planning for these factors and result analysis were carried out using Minitab (version 18.0) software (Minitab Inc., PA, U.S.A.). L8 array comprising of these factors and their respective levels is shown in Table 1.

Optimization of process parameters using response surface methodology Response Surface Methodology (RSM) is widely used for constructing and exploring estimated functional relationship between a response variable and design variables involving


8

Page 9 of 41 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


extraction of phytochemicals

38-40

. Based on the screening study, ultrasound amplitude, volume

of hydrotropic solution, ultrasound power and sonication time have been considered for optimization and modeling as shown in Table 2. Cycle time and concentration of hydrotrope were kept constant at 70 % and 1 M, respectively.

Second order polynomial which includes all interaction terms was used for the model equation and prediction.

݅=4

Y = ߚ0 + ෍ ߚ݅ ܺ݅ + ݅=1

݅=4

෍ ߚ݅݅ ܺ݅2 ݅=1

݅=4

+ ෍ ෍ ߚ݆݅ ܺ݅ ݆ܺ ݅ 0.75

47

. Moreover, the Radj2 = 0.8304 value determines the importance of the model.

No

significant difference between R2 and Radj2 values was found, which shows the desirability of the model. The model F value and p value were found to be 11.14 and less than 0.0001, respectively. This also reveals that model is significant. There is only 0.01 % probability for F value to be large because of error or noise. The coefficient of determination was 0.91, indicating that 91 % of the experimental yield values matched the model-predicted values.

The lack of fit, a measure for the fitness of model, was insignificant (p > 0.05). Thus, the number of experiments was sufficient to determine the effects of independent variables on geraniol yield.

The Rpred2 = 0.5885 was in reasonable agreement with Radj2 = 0.8304, since the difference between these values was less than 0.3. Further, the adequate precision was 11.585, thus, the mathematical model was adequate and could be used to navigate the design space. The model was fitted to the following second order polynomial equation and was used to predict the yield.


14

Page 15 of 41 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Y = 1.61 – 0.19 A + 0.092 B + 0.024 C - 0.13 D + 6.62*10-3 AB + 0.037 AC - 0.337*10-3 AD + 5.494*10-4 BC - 0.031 BD + 1.387*10-3 CD - 0.052 A2 - 0.067 B2 - 0.14 C2 - 4.725*10-3 D2

(2)

The equation in terms of coded factors was used to determine the relative impact of each factor while the equation in terms of actual factors was applied to make prediction of the response at a given level of each factor. A plot of predicted yield against actual yield is shown in Figure 3. The data points are splited evenly by 45o line which suggests that model equation prediction was good.

The order of factors affecting the extraction yield, based on F value can be written as: ultrasound amplitude (A) > sonication time (D) > volume of hydrotropic solution (B) > ultrasound power (C)

The influence of A, B, D, A2, B2, C2 on the extraction yield was highly significant (p < 0.0001). The insignificant terms (p > 0.05) were removed from the equation to improve the model. The modified equation is presented below.

Y = 1.61 – 0.19 A + 0.092 B - 0.13 D - 0.052 A2 - 0.067 B2 - 0.14 C2

(3)

To explore the consequences of extraction variables on the response, three-dimensional (3-D) response surface plots were constructed by keeping the dependent variable on the z-axis against two extraction variables. 3-D surface graphs were also useful to get the maximum, minimum and middle points


15


Page 16 of 41

Figure 4a shows the interaction effect of ultrasound amplitude (A) and volume (B) on the yield of geraniol while Figure 4b represents the interaction between ultrasound amplitude (A) and power (C).

Using the optimization tool, optimum set of conditions was obtained as 65 % ultrasound amplitude, 65 mL volume of hydrotropic solution, 60 W ultrasound power and 16 min of sonication time along with 1.8919 % (w/w) predicted yield (desirability = 0.907).

Additional experiments were performed to confirm the yield of geraniol under the optimized conditions, which was found to be 1.9012 % (w/w) and in good agreement with the predicted one (Table 5). The optimum conditions were, further, investigated for observing changes in the yield by varying cycle time and hydrotrope concentration (Table 5). In case of lower cycle time, the operation time for transducer reduces thereby dampening the effect of fluid stream velocity in presence of viscous drag during off time. This results in reduction of net fluid stream velocity and cushioned impact on cell wall, microjet phenomena and turbulence; and finally, reduced yield. In case of continuous mode, high thermal energy dissipation might have contributed to the degradation of the solute as reflected in the reduced yield. For a higher hydrotrope concentration, the results were not encouraging which might be because of hampered mass transfer characteristics and degradation of the solute. A lower concentration of hydrotrope (0.2 M) might not be sufficient enough to carry out complete extraction.

Thus, 1 M concentration of

hydrotrope and 70 % duty cycle were sufficient to carry out the efficient extraction of geraniol from the leaves of palmarosa.


16

Page 17 of 41 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Moreover, the experiments were performed without sonication while keeping other parameters constant (except time) to understand the influence of ultrasound on extraction. While extracting geraniol without the aid of ultrasound, agitation was provided to have the solid particles in suspension and have uniform mass transfer. In this case, the yield of geraniol was found to be 1.0476 % (w/w) at 16 min and reached the maximum value of 1.6082 % (w/w) at 3 h. The amount of solute extracted was found to be less (15.41 %) compared to the yield of UAHE. This could be explained with two aspects i) for dissolution of solute from plant matrix, swelling of plant material followed by diffusion of solute to the bulk takes place. During this transfer, a stagnant layer of solvent is formed between plant material and bulk solution. This restricts the mass transfer between the plant material and the solution by acting as a diffusion barrier, thereby, drastically reducing the rate of mass transfer

32

, ii) hydrotropes used in extraction

perform two tasks, viz., increasing the permeability by dissolving or destructing cell wall and solubilizing the targeted component. A higher concentration (approximate 2 M) of hydrotropes augments this phenomenon as reported by various researchers

18-20

. However, in the present

study it was much less than the reported one, thereby decreasing the rate of above process. In case of ultrasound treatment, cell wall damage, ease of solvent penetration and either breaking or replenishment of stagnant layer were possible due to collapse of asymmetric bubble near the surface. In addition, an increased turbulence and micro mixing in the solution can enhance the movement of solute transfer in the bulk solution.

The purity of geraniol extracted using UAHE was 97.96 % while the essential oil obtained using hydrodistillation for the same plant material contained 88.9 % geraniol having 1.6326 %


17


Page 18 of 41

(w/w) yield along with the presence of geranyl acetate (3.7 %), linalool (1.1 %), geranial (2.3 %) and traces of other compounds. Thus, a high valued geraniol was obtained using UAHE compared to the conventional way of extraction and thereby enhancing the commercial value.

SEM analysis Ultrasound induced cavitation produces microjets due to implosion of bubbles. The implosion further contributes to turbulence and micro mixing. These phenomena engender various physical changes leading to increased penetration of solvent by changing permeability or rupturing cell walls 15,32. The inclusion of hydrotropes may affect the magnitude of these effects due to its very low surface tension as compared to water (̴ 43 mN/m vs 72 mN/m) (microviscosity ̴ 0.60 P)

48

48

and high viscosity

. Changes in the leaves matrix because of hydrotrope and sonication

were analyzed using SEM as shown in Figure 5. Figures 5 (a - c) show variation in the plant matrix subjected to UAHE under optimized conditions. The vigorous changes can be observed indicating synergistic impact of hydrotrope and ultrasound. Increased wettability by presence of hydrotropes and hammer-type impact

32

of solution due to sonication have resulted in various

effects like local shear force, erosion, fragmentation and detexturation as explained by Chemat et

al.

15

. These phenomena allowed the rapid release of the solute from the cell followed by

dissolution as well as deep penetration of hydrotrope into plant matrices for solubilizing the target product. In case of hydrotropic treatment without ultrasound, small changes were observed for extraction time of 16 min (Figure 5d) while for 3 h (Figure 5e), severe modifications similar to UAHE have been observed. This observation suggests that the extreme changes in the leaf morphology by hydrotrope alone was possible but it was a time consuming step, thereby becoming the rate limiting step and making the overall mass transfer process sluggish in nature.


18

Page 19 of 41 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Therefore, incorporation of sonication in hydrotropic extraction has resulted in overcoming this slothful behavior.

Outcome of the study Concerted efforts for embedding two distinct extraction techniques have resulted in promising outcomes. Not only a faster extraction rate was achieved, but consumption of hydrotrope was also reduced. The shortened extraction time in turn required less power consumption for completion of extraction and shrunken carbon footprint as seen from Table 5. Reduced hydrotrope requirement can lessen the water requirement for solute recovery by diluting hydrotropic solution. This, further, condenses the thermal energy requirement for reconcentrating the hydrotropic solution for extraction. Even during partitioning with organic solvent, the demand of solvent could be less due to comparatively low viscosity at 1 M. The NaCuS solution after extraction and partitioning was reused as such for extraction purpose up to next two stages. During extraction and filtration around 5 mL solution was lost; hence, it was made up to have 65 mL volume before utilizing for extraction. Almost constant relative viscosity of hydrotropic solution used in all the stages was observed, suggesting a little variation in the concentration. In the second stage of extraction, the yield of geraniol was found to be 1.8432 % (w/w) while in the third stage, 1.8405 % (w/w) yield of geraniol was obtained. Thus, recycling of aqueous hydrotropic solution after mere filtration was possible with a negligible drop in the yield. These features of UAHE can improve the financial prospects of the process, a critical factor for a higher scale study. For scaling up UAHE, multi-probe extractor can be designed with variable power option. The probes can be placed based on the intensity at various locations. Thoughtful design along with obtained processing conditions may help in achieving high rate of return and


19


Page 20 of 41

reduced break-even point at a higher scale. Technology incorporating UAHE is expected to improve product quality, process parameters and reduce operational cost 49.

CONCLUSION Ultrasound assisted hydrotropic extraction (UAHE) was employed for isolation of geraniol from the leaves of palmarosa. Various parameters viz., ultrasound amplitude, cycle time, volume and concentration of hydrotropic solution, sonication power and extraction time affecting UAHE were investigated using the Taguchi method followed by optimization using central composite response surface design. From the experimental data, a second order polynomial mathematical model was developed for the response. The maximum yield (1.9012 % w/w) was obtained under the optimized conditions, viz., 65 % of ultrasound amplitude, 70 % cycle time, 65 mL volume of 1 M NaCuS solution, 60 W ultrasound power and 16 min of extraction time. The ultrasound amplitude was the most influencing parameter affecting the process. The current technique has provided a better product yield along with the shortened extraction time and reduced hydrotrope consumption against hydrotropic extraction without sonication. The microscopic study was useful to understand the extraction phenomena. A synergistic effect between hydrotrope and ultrasound has offered sustainability to the existing novel techniques. This novel eco-extraction method can further be employed for extracting valuable compounds from various plant materials and for evaluating possibilities for a higher scale application.

ACKNOWLEDGEMENT We are thankful to Sardar Vallabhbhai National Institute of Technology, Surat, India for the financial support under the head of Institute Research grant.


20

Page 21 of 41 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


REFERENCES 1) Kumar, A.; Shukla, R.; Singh, P.; Dubey, N. K. Biodeterioration of some herbal raw materials by storage fungi and aflatoxin and assessment of Cymbopogon flexuosus essential oil and its components as antifungal. Int. Biodeterior. Biodegradation. 2009,

63 (6), 712−716. (DOI: 10.1016/j.ibiod.2009.03.011) 2) Burt, S. Essential oils: their antibacterial properties and potential applications in foods −

a

review.

Int.

J.

Food

Microbiol.

2004,

94

(3),

223−253.

(DOI:

10.1016/j.ijfoodmicro.2004.03.022) 3) Mallavarapu, G. R.; Rao, B. R. R.; Kaul, P. N.; Ramesh, S; Bhattacharya, A. K. Volatile constituents of the essential oils of the seeds and the herb of palmarosa (Cymbopogon martinii (Roxb.) Wats. var. motia Burk.). Flavour Fragr. J. 1998, 13 (3), 167-169.

(DOI:

10.1002/(SICI)1099-1026(199805/06)13:33.0.CO;2-B) 4) Bard, M.; Albrecht, M. R.; Gupta, N.; Guynn, C. J; Stillwell, W. Geraniol interferes with membrane functions in strains of Candida and Saccharomyces. Lipids 1988, 23 (6), 534-538. (DOI: 10.1007/BF02535593) 5) Kumaran, A. M.; D'Souza, P.; Agarwal, A.; Bokkolla, R. M; Balasubramaniam, M. Geraniol, the putative antihelmintic principle of Cymbopogon martinii. Phytother. Res.

2003, 17 (8), 957. (DOI: 10.1002/ptr.1267)


21


Page 22 of 41

6) Barnard, D. R; Xue, R. D. Laboratory evaluation of mosquito repellents against Aedes

albopictus, Culex nigripalpus, and Ochlerotatus triseriatus (Diptera: Culicidae). J. Med. Entomol. 2004, 41 (4), 726-730. (DOI: 10.1603/0022-2585-41.4.726) 7) Chen, W.; Viljoen, A. M. Geraniol- a review of a commercially important fragrance material. S. Afr. J. Bot. 2010, 76 (4), 643-651. (DOI: 10.1016/j.sajb.2010.05.008) 8) Lapczynski, A.; Bhatia, S. P.; Foxenberg, R. J.; Letizia, C. S.; Api, A. M. Fragrance material review on geraniol. Food Chem. Toxicol. 2008, 46 (11), S160-S170. (DOI: 10.1016/j.fct.2008.06.048) 9) Smitha, G. R.; Rana, V. S. Variations in essential oil yield, geraniol and geranyl acetate contents in palmarosa (Cymbopogon martinii, Roxb. Wats. var. motia) influenced by inflorescence development. Ind. Crops Prod. 2015, 66, 150-160. (DOI: 10.1016/j.indcrop.2014.12.062) 10) Kakaraparthi, P. S.; Srinivas, K. V. N. S.; Kumar, J. K.; Kumar, A. N.; Rajput, D. K.; Anubala, S. Changes in the essential oil content and composition of palmarosa (Cymbopogon martini) harvested at different stages and short intervals in two different seasons. Ind. Crops Prod. 2015, 69, 348-354. (DOI: 10.1016/j.indcrop.2015.02.020) 11) Rao, B. R. R.; Kaul, P. N.; Syamasundar, K. V; Ramesh, S. Chemical profiles of primary and secondary essential oils of palmarosa (Cymbopogon martinii (Roxb.) Wats var.

motia

Burk.). Ind.

Crops

Prod.

2005,

21

(1),

121-127.

(DOI:

10.1016/j.indcrop.2004.02.002)


22

Page 23 of 41 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


12) Desai, M.; Parikh, J; Parikh, P.A. Extraction of natural products using microwaves as a heat source. Sep. Purif. Rev. 2010, 39 (1-2), 1-32. (DOI: 10.1080/15422111003662320) 13) Chemat, F.; Vian, M. A; Cravotto, G. Green extraction of natural products: concept and principles. Int. J. Mol. Sci. 2012, 13 (7), 8615-8627. (DOI: 10.3390/ijms13078615) 14) Rombaut, N.; Tixier, A.; Bily, A; Chemat, F. Green extraction processes of natural products as tools for biorefinery. Biofuel. Bioprod. Biorefin. 2014, 8 (4), 530-544. (DOI: 10.1002/bbb.1486) 15) Chemat, F.; Rombaut, N.; Sicaire, A. G.; Meullemiestre, A.; Fabiano-Tixier, A. S.; Abert-Vian, M. Ultrasound assisted extraction of food and natural products. mechanisms, techniques, combinations, protocols and applications. a review. Ultrason.

Sonochem. 2017, 34, 540-560. (DOI: 10.1016/j.ultsonch.2016.06.035) 16) Subbarao, C. V.; Chakravarthy, I. P. K.; Sai Bharadwaj, A. V. S. L.; Prasad, K. M. M. Functions of hydrotropes in solutions. Chem. Eng. Technol. 2012, 35 (2), 225-237. (DOI: 10.1002/ceat.201100484) 17) Eastoe, J.; Hatzopoulos, M. H.; Dowding, P. J. Action of hydrotropes and alkylhydrotropes. Soft Matter 2011, 7 (13), 5917-5925. (DOI: 10.1039/C1SM05138E) 18) Subramaniam, S.; Palanisamy, A.; Sivasubramanian, A. An unique solvent assisted ‘green’ hydrotropic precipitation and response surface optimization for isolation of the dietary

micronutrient

β-sitosterol-d-glucopyranoside

from

Desmostachya

bipinnata. RSC Adv. 2015, 5 (10), 7479-7484. (DOI: 10.1039/C4RA13923B)


23


Page 24 of 41

19) Mishra, S. P.; Gaikar, V.G. Aqueous hydrotropic solution as an efficient solubilizing agent

for

andrographolide

from

Andrographis

paniculata

leaves. Sep.

Sci

Technol. 2006, 41 (6), 1115-1134. (DOI: 10.1080/01496390600633675) 20) Dandekar, D. V.; Jayaprakasha, G. K.; Patil, B. S. Hydrotropic extraction of bioactive limonin from sour orange (Citrus aurantium L.) seeds. Food Chem. 2008, 109 (3), 515520. (DOI: 10.1016/j.foodchem.2007.12.071) 21) Sharma, R. A.; Gaikar, V. G. Hydrotropic extraction of reserpine from Rauwolfia

vomitoria

Roots. Sep.

Sci.

Technol.

2012,

47

(6),

827-833.

(DOI:

10.1080/01496395.2011.635623) 22) Desai, M. A.; Parikh, J. Hydrotropic extraction of citral from Cymbopogon flexuosus (Steud.)

Wats. Ind.

Eng.

Chem.

Res.

2012, 51

(9),

3750-3757.

(DOI:

10.1021/ie202025b) 23) Nagarajan, J.; Heng,W. W.; Galanakis, C. M.; Ramanan, R. N.; Raghunandan, M. E.; Sun, J.; Ismail, A.; Beng-Ti, T.; Prasad, K. N. Extraction of phytochemicals using hydrotropic

solvents. Sep.

Sci.

Technol.

2016,

51

(7),

1151-1165.

(DOI:

10.1080/01496395.2016.1143842) 24) Ansari, K. B., Gaikar, V. G. Green hydrotropic extraction technology for delignification of sugarcane bagasse by using alkybenzene sulfonates as hydrotropes.

Chem. Eng. Sci. 2014, 115, 157-166. (DOI: 10.1016/j.ces.2013.10.042) 25) Lebeuf, R.; Illous, E.; Dussenne, C.; Molinier, V.; Silva, E. D.; Lemaire, M.; Aubry, J. Solvo-surfactant properties of dialkyl glycerol ethers: application as eco-friendly


24

Page 25 of 41 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


extractants of plant material through a novel hydrotropic cloud point extraction (HCPE) process.

ACS

Sustain.

Chem.

Eng. 2016,

4

(9),

4815-4823.

(DOI:

10.1021/acssuschemeng.6b01101) 26) Shirsath, S. R.; Sonawane, S. H; Gogate, P. R. Intensification of extraction of natural products using ultrasonic irradiations-a review of current status. Chem. Eng. Process.

2012, 53, 10-23. (DOI: 10.1016/j.cep.2012.01.003) 27) Tiwari, B. K. Ultrasound: a clean, green extraction technology. TrAC, Trends Anal.

Chem. 2015, 71, 100-109. (DOI: 10.1016/j.trac.2015.04.013) 28) Vilkhu, K.; Mawson, R.; Simons, L.; Bates, D. Applications and opportunities for ultrasound assisted extraction in the food industry-a review. Innov. Food Sci. Emerg.

Technol. 2008, 9 (2), 161-169. (DOI: 10.1016/j.ifset.2007.04.014) 29) Chemat, F.; Rombaut, N.; Meullemiestre, A.; Turk, M.; Perino, S.; Fabiano-Tixier, A. S.; Abert-Vian, M. Review of green food processing techniques. preservation, transformation, and extraction. Innov. Food Sci. Emerg. Technol. 2017, 41, 357-377. (DOI: 10.1016/j.ifset.2017.04.016) 30) Li, Y.; Fabiano-Tixier, A. S.; Tomao, V.; Cravotto, G.; Chemat, F. Green ultrasoundassisted extraction of carotenoids based on the bio-refinery concept using sunflower oil as an alternative solvent. Ultrason. Sonochem. 2013, 20 (1), 12-18. (DOI: 10.1016/j.ultsonch.2012.07.005)


25


Page 26 of 41

31) Sicaire, A. G.; Vian, M. A.; Fine, F.; Carre, P.; Tostain, S.; Chemat, F. Ultrasound induced green solvent extraction of oil from oleaginous seeds. Ultrason. Sonochem.

2016, 31, 319-329. (DOI: 10.1016/j.ultsonch.2016.01.011) 32) Saleh, I. A.; Vinatoru, M.; Mason, T. J.; Abdel-Azim, N. S.; Aboutabl, E. A.; Hammouda, F. M. A possible general mechanism for ultrasound-assisted extraction (UAE) suggested from the results of UAE of chlorogenic acid from Cynara scolymus L.

(artichoke)

leaves. Ultrason.

Sonochem.

2016,

31,

330-336.

(DOI:

10.1016/j.ultsonch.2016.01.002) 33) Keswani, M.; Raghavan, S.; Deymier, P. Effect of non-ionic surfactants on transient cavitation in a megasonic field. Ultrason. Sonochem. 2013, 20 (1), 603-609. (DOI: 10.1016/j.ultsonch.2012.05.018) 34) Thakker, M. R.; Parikh, J. K.; Desai, M. A. Microwave assisted extraction of essential oil from the leaves of Palmarosa: multi-response optimization and predictive modelling. Ind. Crops Prod. 2016, 86, 311-319. (DOI: 10.1016/j.indcrop.2016.03.055) 35) Sharif, K. M.; Rahman, M. M.; Azmir, J;, Mohamed, A.; Jahurul, M. H. A.; Sahena, F.; Zaidul, I. S. M. Experimental design of supercritical fluid extraction – a review. J.

Food Eng. 2014, 124, 105-116. (DOI: 10.1016/j.jfoodeng.2013.10.003) 36) Ross, P. J. Taguchi Techniques for Quality Engineering; McGraw- Hill Book Co: New York, U.S.A., 1989. 37) Taguchi, G.; Chowdhury, S.; Wu, Y. Taguchi’s Quality Engineering Handbook; John Wiley and Sons: New York, U.S.A., 2005.


26

Page 27 of 41 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


38) Yoswathana, N. Optimization of ScCO2 extraction of rambutan seed oil using response surface methodology. Int. J. Chem. Eng. Appl. 2013, 4 (4), 187-190. (DOI: 10.7763/IJCEA.2013.V4.291) 39) Xu, Q.; Shen, Y.; Wang, H.; Zhang, N.; Xu, S.; Zhang, L. Application of response surface methodology to optimize extraction of flavonoids from fructus sophorae. Food

Chem. 2013, 138 (4), 2122-2129. (DOI: 10.1016/j.foodchem.2012.11.099) 40) Azmir, J.; Zaidul, I. S. M.; Rahman, M. M.; Sharif, K.M.; Sahena, F.; Jahurul, M. H. A.; Mohamed, A. Optimization of oil yield of Phaleria macrocarpa seed using response surface methodology and its fatty acids constituents. Ind. Crops Prod.

2014, 52, 405-412. (DOI: 10.1016/j.indcrop.2013.11.009) 41) Booth, J. J.; Abbott, S.; Shimizu, S. Mechanism of hydrophobic drug solubilization by small molecule hydrotropes. J. Phys. Chem. B 2012, 116 (51), 14915-14921. (DOI: 10.1021/jp309819r) 42) Shimizu, S.; Matubayasi, N. Hydrotropy: monomer–micelle equilibrium and minimum hydrotrope concentration. J. Phys. Chem. B 2014, 118 (35), 10515-10524. (DOI: 10.1021/jp505869m) 43) Booth, J. J.; Omar, M.; Abbott, S.; Shimizu, S. Hydrotrope accumulation around the drug: the driving force for solubilization and minimum hydrotrope concentration for nicotinamide and urea. Phys. Chem. Chem. Phys. 2015, 17 (12), 8028-8037. (DOI: 10.1039/c4cp05414h)


27


Page 28 of 41

44) Goula, A. M.; Ververi, M.; Adamopoulou, A.; Kaderides, K. Green ultrasound-assisted extraction of carotenoids from pomegranate wastes using vegetable oils. Ultrason.

Sonochem. 2017, 34, 821-830. (DOI: 10.1016/j.ultsonch.2016.07.022) 45) Purohit, A. J.; Gogate, P. R. Ultrasound-assisted extraction of β-carotene from waste carrot residue: effect of operating parameters and type of ultrasonic irradiation. Sep. Sci

Technol. 2015, 50 (10), 1507-1517. (DOI: 10.1080/01496395.2014.978472) 46) Li, H.; Chen, B.; Yao, S. Application of ultrasonic technique for extracting chlorogenic acid from Eucommia ulmodies Oliv. (E. ulmodies). Ultrason. Sonochem. 2005, 12 (4), 295-300. (DOI: 10.1016/j.ultsonch.2004.01.033) 47) Chauhan, B.; Gupta, R. Application of statistical experimental design for optimization of alkaline protease production from Bacillus sp. RGR-14. Process Biochem. 2004, 39 (12), 2115-2122. (DOI: 10.1016/j.procbio.2003.11.002) 48) Balasubramanian, D.; Srinivas, V.; Gaikar, V. G.; Sharma, M. M. Aggregation behavior of hydrotropic compounds in aqueous solution. J. Phys. Chem. 1989, 93 (9), 3865-3870. (DOI: 10.1021/j100346a098) 49) Pingret, D.; Fabiano-Tixier, A.; Le Bourvellec, C.; Renard, C. M. G. C.; Chemat, F. Lab and pilot-scale ultrasound-assisted water extraction of polyphenols from apple pomace. J. Food Eng. 2012, 111 (1), 73-81. (DOI: 10.1016/j.jfoodeng.2012.01.026)


28

Page 29 of 41 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


List of Tables Table 1. L8 orthogonal array, yield and S/N ratio Table 2. Variables and their levels Table 3. Design matrix using CCD (uncoded variables) and experimental results Table 4. Analysis of variance for response surface quadratic model Table 5. Confirmation experiment and comparison

List of Figures Figure 1. Effect of different concentrations of various hydrotropes on solubility Figure 2. Effect of different parameters on S/N ratio Figure 3. Predicted yield vs. actual yield for UAHE Figure 4. Response surface plots showing interaction effect of different parameters on geraniol yield.

Figure 5. SEM analysis (a, b, c) different views of leaves treated in UAHE, (d) view of leaf after HE treatment of 16 min, (e) view of leaf after HE treatment of 180 min


29


Page 30 of 41

Table 1. L8 orthogonal array, yield and S/N ratio

Exp. No.

Yield of geraniol (%, w/w) S/N ratio

Factors A

B

C

1

1 (20)

1 (50)

2

1

3

D

E

F

Y1

Y2

1 (40) 1 (0.2)

1 (20)

1 (4)

0.7780

0.7719

-2.2147

1

1

2 (80)

2 (20)

1.0280

1.0199

0.2054

1

2 (100)

2 (80) 1

1

2

1.8480

1.8747

5.3959

4

1

2

2

2

2

1

0.9774

0.9821

-0.1778

5

2(80)

1

2

1

2

1

1.0285

1.0251

0.2297

6

2

1

2

2

1

2

0.9309

0.9395

-0.5822

7

2

2

1

1

2

2

0.5781

0.5814

-4.7353

8

2

2

1

2

1

1

0.7760

0.7666

-2.2560

2 (1.8)

A: Ultrasound amplitude (%), B: Cycle time (%), C: Volume of hydrotropic solution (mL), D: Hydrotrope concentration (M), E: Ultrasonic power (W), F: Sonication time (min), Values in the bracket show the physical values of the factor.


30

Page 31 of 41 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Table 2. Variables and their levels Independent variables

Levels -α

-1

0

1

+α

Ultrasound amplitude (%) (A)

20

35

50

65

80

Volume of hydrotropic solution (mL) (B)

40

50

60

70

80

Ultrasound power (W) (C)

20

40

60

80

100

Sonication time (min) (D)

4

8

12

16

20


31


Page 32 of 41

Table 3. Design matrix using CCD (uncoded variables) and experimental results Volume of hydrotropic Ultrasound Ultrasound power (W) amplitude (%) solution(mL) (A) (B) (C)

of Sonication Yield time (min) geraniol (%, w/w) (D)

1

-1 (35)

-1 (50)

-1 (40)

-1 (8)

0.9856

2

1 (65)

-1

-1

-1

1.2956

3

-1

1 (70)

-1

-1

1.1256

4

1

1

-1

-1

1.4684

5

-1

-1

1 (80)

-1

0.8523

6

1

-1

1

-1

1.4351

7

-1

1

1

-1

1.0536

8

1

1

1

-1

1.6785

9

-1

-1

-1

1 (16)

1.1708

10

1

-1

-1

1

1.5616

11

-1

1

-1

1

1.2423

12

1

1

-1

1

1.6852

13

-1

-1

1

1

1.214

14

1

-1

1

1

1.6632

15

-1

1

1

1

1.2605

16

1

1

1

1

1.6887

17

-2 (20)

0 (60)

0 (60)

0 (12)

1.1552

18

2 (80)

0

0

0

1.6745

19

0 (50)

-2 (40)

0

0

1.0565

20

0

2 (80)

0

0

1.6523

21

0

0

-2 (20)

0

0.9865

Run No.


32

Page 33 of 41 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


22

0

0

2 (100)

0

1.1234

23

0

0

0

-2 (4)

1.2112

24

0

0

0

2 (20)

1.9985

25

0

0

0

0

1.6523

26

0

0

0

0

1.5895

27

0

0

0

0

1.4523

28

0

0

0

0

1.6582

29

0

0

0

0

1.7523

30

0

0

0

0

1.5541

Values in the parentheses are decoded form of variables, , A-Ultrasound amplitude (%), BVolume of hydrotropic solution (mL), C- Ultrasound power (W), D- Extraction time (min)


33


Page 34 of 41

Table 4. Analysis of variance for response surface quadratic model Source

SS

DF

MS

F value

p – value

Model

2.21

14

0.16

11.14

< 0.0001

A

0.89

1

0.89

62.36

< 0.0001

B

0.20

1

0.20

14.41

0.0018

C

0.014

1

0.014

1.00

0.3325

D

0.42

1

0.42

29.42

< 0.0001

AB

7.024*10-4

1

7.024*10-4

0.049

0.8270

AC

0.022

1

0.022

1.58

0.2284

AD

1.395*10-3

1

1.395*10-3

0.098

0.7583

BC

4.829*10-6

1

4.829*10-6

3.401*10-4

0.9855

BD

0.015

1

0.015

1.06

0.3199

CD

3.077*10-5

1

3.077*10-5

2.167*10-3

0.9635

A2

0.075

1

0.075

5.27

0.0366

B2

0.12

1

0.12

8.76

0.0097

C2

0.55

1

0.55

39.06

< 0.0001

D2

6.123*10-4

1

6.123*10-4

0.043

0.8383

Lack of Fit

0.1602

10.0000 0.0160

1.5180

0.3373

R2

0.9123

Radj 2

0.8304

RPred 2

0.5885

Adeq Precision

11.5846

Significant

Not significant

DF=Degrees of freedom, SS = Sum of square, MS = Mean square, A-Ultrasound amplitude (%), B- Volume of hydrotropic solution (mL), C- Ultrasound power (W), D- Extraction time (min)


34

Page 35 of 41 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Table 5. Confirmation experiment and comparison Yield of geraniol (%, w/w)

Operating Parameters Method

UAHE

HE

Ultrasound amplitude

Volume of Ultrasound hydrotropic power solution

Sonication time*

Cycle time

Hydrotrope concentration

65

65

60

16

70

1

1.9012

65

65

60

16

40

1

1.5298

65

65

60

16

100

1

1.7825

65

65

60

16

70

0.2

1.7121

65

65

60

16

70

1.8

1.6213

-

65

-

16

-

1

1.0476

-

65

-

60

-

1

1.2986

-

65

-

120

-

1

1.4842

-

65

-

180

-

1

1.6082

*In case of HE, it is extraction time


35


Page 36 of 41

Figure 1. Effect of different concentrations of various hydrotropes on solubility


36

Page 37 of 41

Main Effects Plot for SN ratios Data Means A

B

C

D

E

F

1.0

0.5

Mean of SN ratios

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


0.0

-0.5

-1.0

-1.5

-2.0

-2.5 1

2

1

2

1

2

1

2

1

2

1

2

Signal-to-noise: Larger is better

Figure 2. Effect of different parameters on S/N ratio


37


Design-Expert® Software Yield of Geraniol

Predicted vs. Actual

Color points by value of Yield of Geraniol: 1.9985

2

0.8523

1.8

1.6

Predicted

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 38 of 41

1.4

1.2

1

0.8

0.8

1

1.2

1.4

1.6

1.8

2

Actual

Figure 3. Predicted yield vs. actual yield for UAHE


38

Page 39 of 41 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(a)

(b)

Figure 4. Response surface plots showing interaction effect of different parameters on geraniol yield


39


Page 40 of 41

Figure 5. SEM analysis (a, b, c) different views of leaves treated in UAHE, (d) view of leaf after HE treatment of 16 min, (e) view of leaf after HE treatment of 180 min


40

Page 41 of 41 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Synopsis: UAHE has the potential to be considered as a sustainable alternative for the isolation of geraniol.


41

Ultrasound Assisted Hydrotropic Extraction: A Greener Approach for

Recommend Documents