Description:FIELD OF THE INVENTION
The present invention relates to the field of emulsions. Particularly, the present invention provides an emulsion liquid membrane (ELM). In particular, the present invention provides Edible oil based Bio-ELMs and process of its synthesis, and stability. Further, the invention provides a method for extraction of pollutants from wastewater by treatment with said Bio-ELM.

BACKGROUND OF THE INVENTION
In the recent years, Emulsion Liquid Membrane (ELM) has garnered much attention, for its simple operation and high selectivity for the target solute. ELM is known for its high selectivity due to the larger interfacial area that permits effective mass transfer. The Emulsion Liquid Membrane (ELM) system can selectively recover solutes even at low concentrations and simultaneously extract and remove solutes from aqueous solutions. Additionally, the ELM can be highly stable, ensuring its effectiveness over extended period. ELM has demonstrated important potential in the field of pollution control.
For a successful ELM process, emulsion stability and formulation of liquid membrane are the two main criteria. The method of contaminant separation by utilizing emulsion liquid membrane involves the dispersal of the emulsion into the aqueous feed phase and the transportation of the constituents across the organic oil phase to arrive at the internal stripping phase as droplets. The main hurdle in the ELM process is emulsion stability, meaning the breakdown of the emulsion to release the internal phase of the outside emulsion droplet. Therefore, it is necessary to reach the target stability level to overcome the application problems. However, the use of chemical components in liquid membrane synthesis can lead to a plethora of issues, including high costs, non-biodegradable, toxicity to the environment, and negative health impacts on living organisms. Some studies and patents have investigated the use of vegetable oils and bio-diluents in ELM synthesis.
CN101108214B discloses a method for extracting alkaloids in coptis chinensis by emulsion liquid membrane separation. The method involves the synthesis of an emulsion using edible oil as film solvent, Span 80 or the mixture of Span 80 and co-surfactant as surfactant, phospholipid as carrier, and Coptidis rhizome hydrochloric acid extract or sulfuric acid extract. The preparation steps involve mixing of all the component under 8000 rev/mins～10000 rev/mins rotating speed, stirring 1- 3min to make stable w/o type emulsion.
ID202406854S discloses a method to treat liquid waste containing methyl orange using emulsion liquid membrane from used cooking oil. The emulsion liquid membrane disclosed in was prepared by dissolving Span 80 as much as 4%, Aliquat 336 as much as 31.3%, and D2EHPA as much as 31.3% and used cooking oil as much as 33.3% in a chemical glass with a volume ratio of 1:3 to the internal phase (made up of a 2M concentration NaOH solution; mixing the internal phase with the liquid membrane phase with a volume ratio of 3:1 by dripping the internal phase into the membrane phase for 50 minutes and stirring at a speed of 1200 rpm to produce an emulsion.
Also, Thakur and Jawa have published a report on synthesizing ELM using rice bran oil, sunflower oil, olive oil, soya bean oil, etc, incorporating Aliquat 336 (Methyltrioctylammonium chloride), [MOIm] Bf4 (1-methyl-3-octylimidazolium tetrafluoroborate), [BMIm] Cl (1-butyl-3-methylimidazolium chloride), [BMIm]Bf4 (1-butyl-3methylimidazolium tetrafluoroborate), [BMIm] Pf6 (1-butyl-3-methylimidazolium hexafluorophosphate) in the membrane phase [Thakur A, Jawa GK. Comparative study on effect of ionic liquids on static stability of green emulsion liquid membrane. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2022, 644,128776]. In a similar way, Q. Yang et al. demonstrated that soybean lecithin can effectively stabilize curcumin-loaded emulsions for up to 30 days, underscoring the bio-compatibility and sustainability of plant-based emulsifiers [Yang Q., Chen Q., Xu L., Liu X., Yuan F., Gao Y., Soybean lecithin-stabilized oil-in-water emulsions increase the stability and in vitro bio-accessibility of bioactive nutrients, Food Hydrocolloids, 2021,117,106708]. Sujatha et al. have synthesized used cooking oil-based ELM using Span 80, D2EHPA for extraction of lead [Sujatha S., Natarajan R., Vasseghian Y., Manivasagan R., Conversion of waste cooking oil into value-added emulsion liquid membrane for enhanced extraction of lead: Performance evaluation and optimization, Chemosphere, 2021, 284, 131385].
Even though numerous studies in the prior art have focussed on the use of edible oils as diluents for the synthesis of the ELMs but, the stability of emulsions still remains a challenging task that has not been optimally addressed leading to a loss in extraction efficiency. Also, the prior art has employed expensive combinations of oils, diluents, and carriers that are mostly hydrocarbon based. Thus, there is a need to develop ELM that can be synthesised using cheaper and bio-degradable materials without compromising on the stability and extraction efficiency.
OBJECTIVES OF THE INVENTION
It is a primary objective of the present invention to provide a Bio-ELM.
It is another objective of the present invention to provide Bio-ELM with higher stability and enhanced pollutant extraction efficiency.
It is another objective of the present invention to provide a Bio-ELM that is cost-effective and environmentally sustainable.
It is another objective of the present invention to provide a process for synthesis of a Bio-ELM.
It is another objective of the present invention to provide a method for extraction of pollutants from wastewater.

SUMMARY OF THE INVENTION
The present invention provides an edible oil-based bio-emulsion liquid membrane (Bio-ELM), wherein, the membrane comprises:
a membrane phase comprising of bio-diluents in a range from 90 to 98 % v/v, surfactant in a range from 1 to 5 % v/v, carrier solvent in a range from 1 to 5 % v/v; and an internal aqueous phase.

The bio diluent is an edible oil selected from sesame oil, soybean oil and olive oil.
The surfactant is a non-ionic surfactant selected from sorbitan monooleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monooleate, octylphenol ethoxylate, and sorbitan monolaurate.
The carrier solvent is selected from xylene, toluene, heptane, pentane and combinations thereof, preferably heptane.
The internal aqueous phase comprises alkali hydroxides, preferably sodium hydroxide, ammonium hydroxide, and potassium hydroxide.
The Bio-ELM is having emulsion droplets of size in a range of 5 to 14 µm.
The present invention also provides a process for synthesizing the edible oil-based bio-emulsion liquid membrane as defined herein, wherein the process comprises steps of:
adding surfactant, carrier solvent and bio-diluent to obtain a membrane phase;
stirring the membrane phase to obtain a membrane phase mix;
adding the internal aqueous phase drop by drop into the membrane phase mix; and
stirring the membrane phase mix with internal aqueous phase to obtain the edible oil-based bio-emulsion liquid membrane.
The surfactant, carrier solvent and bio-diluent are added in a percent ratio of 2:2:96 v/v.
The stirring of membrane phase is carried out at 2000 rpm to 4000 rpm for 45 minutes to 75 minutes and wherein the stirring of membrane phase mix with the internal aqueous phase is carried out at 1000 rpm to 2000 rpm for 15 minutes to 25 minutes.
The present invention further provides a method for extraction of pollutants from wastewater by contacting edible oil-based bio-emulsion liquid membrane as defined herein with the wastewater under continuous mixing at a pH in a range of 6 to 8.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 illustrates a schematic representation of process for synthesis of Bio-emulsion liquid membrane.
Figure 2 illustrates images of synthesized Bio-ELMs a) Sesame oil b) Soybean oil and c) Olive oil.
Figure 3 illustrates creaming index (CI) analysis of Bio-ELM and synthetic ELM by separated layers after 3 days for a) sesame oil, b) soybean oil, c) olive oil, and d) synthetic ELM.
Figure 4 illustrates analysis of emulsion stability by creaming index (%) of Bio-ELM and synthetic ELM after a storage time of 3 days.
Figure 5 illustrates microscopic images for the emulsion droplets of Bio-ELMs (day 1 to day 3): a) olive oil Bio-ELM b) sesame oil Bio-ELM c) soybean oil Bio-ELM d) synthetic ELM.
Figure 6 illustrates schematic representation of the emulsion coalescence process in Bio-ELMs after a certain period of time.
Figure 7 illustrates phase separation study for (a) soybean oil and olive oil Bio-ELM, (b) sesame oil Bio-ELMs by H/H0 verses time (min/hr).
Figure 8 illustrates captured pictures of soybean oil and olive oil Bio-ELM during the phase separation observation (0 to 90 minutes).
Figure 9 illustrates captured pictures of sesame oil Bio-ELM during the phase separation observation (1 to 6 days).
Figure 10 illustrates phase separation and microscopic analysis comparison of Bio-ELM and synthetic ELM.
Figure 11 illustrates captured pictures of the methylene (MB) dye colour reduction.
Figure 12 illustrates microscopic analysis of emulsion for (a) prior art. (b) present invention.
Figure 13 illustrates results for Interfacial Tension (IFT) Analysis of prior art and present invention.

DETAILED DESCRIPTION OF THE INVENTION
For convenience, before further description of the present disclosure, certain terms employed in the specification, and examples are delineated here. These definitions should be read in light of the remainder of the disclosure and understood as by a person of skill in the art.
The terms used herein have the meanings recognized and known to those of skill in the art, however, for convenience and completeness, particular terms and their meanings are set forth below. The articles “a”, “an” and “the” are used to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article.
The terms “comprise” and “comprising” are used in the inclusive, open sense, meaning that additional elements may be included. It is not intended to be construed as “consists of only”. The term "at least one" is used to mean one or more and thus includes individual components as well as mixtures/combinations. Throughout this specification, unless the context requires otherwise the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to imply the inclusion of a stated element or step or group of element or steps but not the exclusion of any other element or step or group of element or steps. The term “including” is used to mean “including but not limited to”. “including” and “including but not limited to” are used interchangeably.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the disclosure, the preferred methods and materials are now described.
The present disclosure is not to be limited in scope by the specific embodiments described herein, which are intended for the purposes of exemplification only. Functionally equivalent products, compositions, and methods are clearly within the scope of the disclosure, as described herein.
The terms “Diluent” and “Bio-diluent” as used herein have been used interchangeably.
The present invention focusses on the synthesis of a Bio-Emulsion Liquid Membrane (Bio-ELM) utilizing edible oils to improve emulsion stability for the separation of wastewater pollutants, including dyes, heavy metals, and toxic compounds. Conventional synthetic ELMs frequently encounter instability, where the emulsion rapidly disintegrates, impairing membrane performance and diminishing separation efficiency. To overcome these challenges, a Bio-ELM was developed using edible oils such as sesame oil, olive oil, and soybean oil as bio-diluents in the membrane phase, combined with a surfactant like sorbitan monooleate and a solvent like n-heptane as the carrier at specific volume ratios (v/v%). The internal aqueous phase contains sodium hydroxide (NaOH), which contributes to forming a stable, white, milky, creamy-textured Bio-ELM.
The present invention overcomes the drawbacks of the prior art, as bio-diluents such as sesame oil, olive oil, and soybean oil are used instead of petrochemical-based materials in the membrane phase of Bio-ELM. The bio-diluents olive, soybean, and sesame oils are biodegradable, environmentally friendly, and provide a sustainable approach that reduces the ecological footprint. Bio-diluents help to stabilize the emulsion for a longer time, which enhances the extraction efficiency. The bio-diluent contributes surface-active components that increase viscosity, enhance interfacial film strength, and sometimes even add antioxidant protection. These effects synergize with the minimal use of surfactant (v/v%), thus reducing the need for higher surfactant loading while forming a stable emulsion.
The Edible oil-based ELM not only enhances long-term emulsion stability but also improves environmental performance in wastewater treatment applications. Compared to traditional hydrocarbon-based diluents like kerosene or cyclohexane, these natural alternatives offer greater membrane stability and ecological safety.
In an aspect, the present invention provides an edible oil-based bio-emulsion liquid membrane (Bio-ELM), wherein, the membrane comprises:
a membrane phase comprising of bio-diluents in a range from 90 to 98 % v/v, surfactant in a range from 1 to 5 % v/v, carrier solvent in a range from 1 to 5 % v/v; and an internal aqueous phase.
In an embodiment of the present invention, the bio diluent is an edible oil selected from sesame oil, soybean oil and olive oil.
In an embodiment of the present invention, the surfactant is a non-ionic surfactant selected from sorbitan monooleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monooleate, octylphenol ethoxylate, and sorbitan monolaurate.
In an embodiment of the present invention, the carrier solvent is selected from xylene, toluene, heptane, pentane and combinations thereof, preferably heptane.
In an embodiment of the present invention, the internal aqueous phase comprises alkali hydroxides, preferably sodium hydroxide, ammonium hydroxide, and potassium hydroxide.
In an embodiment of the present invention, the Bio-ELM is having emulsion droplets of size in a range of 5 to 14 µm.
In another aspect, the present invention provides a process for synthesizing the edible oil-based bio-emulsion liquid membrane as defined herein, wherein the process comprises steps of:
adding surfactant, carrier solvent and bio-diluent to obtain a membrane phase;
stirring the membrane phase to obtain a membrane phase mix;
adding the internal aqueous phase drop by drop into the membrane phase mix; and
stirring the membrane phase mix with internal aqueous phase to obtain the edible oil-based bio-emulsion liquid membrane.
In an embodiment of the present invention, the surfactant, carrier solvent and bio-diluent are added in a percent ratio of 2:2:96 v/v.
In an embodiment of the present invention, the stirring of membrane phase is carried out at 2000 rpm to 4000 rpm for 45 minutes to 75 minutes and wherein the stirring of membrane phase mix with the internal aqueous phase is carried out at 1000 rpm to 2000 rpm for 15 minutes to 25 minutes.
In a further aspect, the present invention further provides a method for extraction of pollutants from wastewater by contacting edible oil-based bio-emulsion liquid membrane as defined herein with the wastewater under continuous mixing at a pH in a range of 6 to 8.
The developed Bio-ELMs show promise for potential application in wastewater treatment processes with a lower sensitivity towards pH, the ELM can be used between pH 6-8, which is close to several water treatment requirements, offering a more sustainable approach to membrane technology.
EXAMPLES:
The present disclosure is further illustrated by reference to the following examples which are for illustrative purposes only and does not limit the scope of the disclosure in any way. These examples are not intended to be inclusive of all aspects of the subject matter disclosed herein, but rather to illustrate representative features, methods, compositions, and results. These examples are not intended to exclude equivalents and variations of the present disclosure, which are apparent to one skilled in art.
Example 1: Synthesis of Bio-emulsion liquid membrane (ELM).
The surfactant sorbitan monooleate (0.4 ml), carrier solvent n-heptane (0.4 ml) and bio-diluent sesame oil (19.2 ml), were added to obtain the membrane phase, and the mixture was stirred at 3000 rpm for 1 hour to obtain the membrane phase mix. Adding the internal aqueous phase containing sodium hydroxide (0.25 N) drop by drop into the membrane phase mix to maintain membrane phase: internal aqueous phase ratio at 1:1 followed by stirring at 1500 rpm for 20 minutes to obtain the white milky creamy textured Bio-ELM (Fig. 1 and Fig. 2).
The Bio-ELMs is compared with conventional synthetic ELMs to analyze emulsion stability through phase separation observations, revealing that Bio-ELMs exhibited superior stability.
Stability study:
The stability of the Bio-ELMs and synthetic ELM was evaluated through microscopic droplet size analysis and creaming index measurements. These methods allow for a comprehensive understanding of the emulsion's behaviour over time. The process of microscopic evaluation is simple and robust.
1(a). Creaming index analysis
Creaming index analysis (Figure 3 and figure 4) was performed to compare the stability of Bio-ELMs with that of synthetic ELMs. A higher creaming index (CI) indicates lower emulsion stability. In the case of Bio-ELMs, formulations using sesame, olive, and soybean oils exhibited lower CI values, indicating enhanced emulsion stability compared to the synthetic ELM.
To predict the emulsions' long-term behavior, coalescence time was examined both theoretically and experimentally. It was observed that Bio-ELMs synthesized with sesame oil demonstrated the highest stability among the oils tested. Specifically, the emulsion coalescence time was recorded as 432,000 seconds for sesame oil-based ELM, 5400 seconds for soyabean oil-based ELM and 4200 seconds for olive oil-based ELM underscoring their significant stability advantages. Higher shear conditions promote finer dispersion of the internal aqueous phase, producing smaller droplets (5-14 µm) with narrower size distribution. Smaller droplets resist coalescence and gravitational settling better, improving overall kinetic and thermodynamic stability. Uniform small droplets reduce the Ostwald ripening phenomenon, where smaller droplets dissolve and redeposit into larger ones. Also, uniform and smaller sizes ensure better emulsifier alignment at the interface, creating robust interfacial films and reducing breakage in the emulsion.
The superior stability of sesame oil-based Bio-ELMs was attributed to its ability to produce smaller droplets, which reduced coalescence and minimized emulsion destabilization.
Microscopic analysis of droplet morphology
Microscopic analysis (Fig. 5) was performed to observe and analyze the changes in emulsion droplet size over time. In the initial observations, Bio-ELM synthesized using sesame oil showed very small (6 ± 0.5 µm), uniform emulsion droplets, indicating high stability. Similarly, Bio-ELMs synthesized with soybean (11 ± 0.5 µm) and olive oils (12.5 ± 0.5 µm) also displayed small and relatively uniform droplets, although slightly less stable than sesame. In contrast, the synthetic ELM exhibited larger droplet sizes (25 ± 0.5 µm) from the beginning, indicating weaker initial stability. Upon storage, significant changes were observed. For the synthetic ELM, by the second and third day, the droplet size increased noticeably, and by the end of the third day, only a few large droplets remained, demonstrating complete emulsion destabilization. In comparison, the Bio-ELMs maintained much better stability, than the synthetic ELM. Sesame Bio-ELM showed only minor changes in droplet size even after three days, reflecting their superior stability. However, for Bio-ELMs based on soybean and olive oils, an increase in droplet size was observed by the second and third days, though they still remained more stable than the synthetic ELM.
Phase separation analysis
The investigation into phase separation was conducted to evaluate the stability of the emulsions. Photographic documentation of both the initial emulsion samples and the resultant separated layers was undertaken for assessment. The bottle test method was employed to examine the phase separation of emulsion phases, which facilitated the identification of coalescence formation. In this method, the emulsion's initial height and the height of the separated layer of emulsion are considered. As illustrated in Fig. 6, the process of emulsion coalescence is depicted schematically. Coalescence refers to the phenomenon where small emulsion droplets amalgamate to form larger droplets due to droplet aggregation. This results in fluctuations; over time, the aggregated droplets merge, forming larger droplets. The stability is determined by measuring the emulsion coalescence time at w/o interface, with results calculated using Equation 1.
H/H_0 = (Height of separated phase at time t (cm))/(Initial emulsion height (cm)) (1)
The H/H0 versus time plot was utilized for phase separation analysis by measuring the separated height of emulsions. The data for olive and soybean oils are presented in Fig. 7 (a), indicating that the phase separation rate for these oils occurred earlier than for sesame oils as shown in Fig. 7 (b), the data were plotted accordingly for enhanced comprehension. The Bio-ELMs of soybean and olive demonstrated reduced stability, as emulsion coalescence was observed at 90 min and 70 min. The sesame Bio-ELMs exhibited superior emulsion stability compared to soybean and olive. As shown in Fig. 7 (b), the values of H/H0 for sesame were observed to be higher. The captured pictures of phase separation are shown in Fig. 8 and Fig. 9. The highest stability was observed for sesame emulsions, with the highest H/H0 value recorded at 120 hours.
Comparative study of Bio-ELM vs. synthetic ELM
For comparing the synthetic ELM vs Bio-ELM, the soybean oil was used as a bio-diluent. Further component details are as follows:
Synthetic ELM components: Membrane phase is Sorbitan Monooleate, n-heptane and cyclohexane (2:2:96 v/v). Internal aqueous phase (NaOH 0.25 N) is used.
Bio-ELM components: Membrane phase is Sorbitan Monooleate, n-heptane, soybean oil (2:2:96 v/v). Internal aqueous phase (NaOH 0.25 N) is used.

Phase separation analysis
The phase separation study was conducted to assess the stability of Bio-ELM and Synthetic ELM over a 30-minute period. As shown in Fig. 10, both emulsions initially appeared homogeneous immediately after synthesis. After 30 minutes, the Bio-ELM exhibited no phase separation. In contrast, the Synthetic ELM showed a pronounced separation of the membrane and internal aqueous phases, with a distinct upper layer forming, indicative of higher emulsion breakage and coalescence. The visual difference suggests that the Bio-ELM possesses superior emulsion stability under the given experimental conditions.
Microscopic analysis of droplet morphology
The emulsion droplets of Bio-ELM were uniformly dispersed with relatively smaller sizes and a narrow size distribution as shown in Fig. 10. The inter-droplet distances were small but without significant aggregation, indicating a strong steric and possibly electrostatic stabilization. Minimal change in droplet morphology was observed after 30 minutes, confirming resistance to coalescence. But in the synthetic ELM, the emulsion droplets displayed a broader size distribution, with larger droplets dominating after 30 minutes. This indicates the coalescence of smaller droplets over time. The appearance of larger spherical droplets, along with visible gaps between them, is consistent with structural destabilization and phase separation observed.
Extraction efficiency
A visual comparison of pollutant methylene blue (MB) dye removal using synthetic ELM and Bio-ELM is shown in Fig. 11. The Bio-ELM achieved 98.90% extraction efficiency, showing near-complete decolorization, while the synthetic ELM achieved 79.45% removal from the initial 20 ppm dye solution.

Comparative study of present invention with the prior art
A comparative study of the present invention with the prior art was done based on the parameters as listed in the table 1 below.
Table 1:-
Parameters Prior art* Present invention
Oils used in Bio-ELM synthesis Sesame oil or Jojoba oil or Olive oil or Clove oil or Rosemary oil or Peppermint oil or Soybean oil Sesame oil or Olive oil or Soybean oil
Stirring speed and time Homogenization at 1500 rpm for 20 minutes Homogenization at 3000 rpm for 60 minutes
Internal aqueous phase addition condition Addition at 800 rpm for 10 minutes Addition at 1500 rpm for 20 minutes
* Wakle M. et al. “Bio-Emulsion Liquid Membrane (Bio-ELM) Synthesis, by using seven different vegetable oils for wastewater treatment” Sep 2023
In the prior art, membrane phase components Sorbitan Monooleate, n-heptane, and selected oil were homogenized at 1500 rpm for 20 minutes, followed by adding the internal aqueous phase (NaOH) at 800 rpm for 10 minutes. Microscopic analysis showed average droplet sizes of 40-45 µm, indicating relatively coarse emulsions as shown in Fig. 12 (a). Whereas in the present invention optimized process parameters were used to enhance emulsion stability and droplet uniformity. The homogenization was done at a speed of 3000 rpm for 60 minutes. Additionally, the internal aqueous phase was added at 1500 rpm for 20 minutes, compared to milder conditions in prior art.
Reduction in droplet Size and improved stability
Higher shear conditions promote finer dispersion of the internal aqueous phase, producing smaller droplets (5-14 µm) with narrower size distribution, as shown in Fig. 12 (b).
Smaller droplets resist coalescence and gravitational settling better, improving overall kinetic and thermodynamic stability.
Uniform small droplets reduce the Ostwald ripening phenomenon, where smaller droplets dissolve and redeposit into larger ones. Also, uniform and smaller sizes ensure better emulsifier alignment at the interface, creating robust interfacial films and reducing breakage in the emulsion.

Interfacial Tension (IFT) Analysis
The interfacial tension (IFT) analysis evaluated the stability of emulsions synthesized using parameters from Prior art and those optimized in the present invention. IFT values were measured over 30 minutes at 5-minute intervals to monitor emulsion destabilization.
The IFT for prior art showed a sharp increase from 5 mN/m at 0 minute to 13.5 mN/m at 30 minutes (Fig. 13), indicating rapid loss of interfacial stability. This rise in IFT reflects weakening of the interfacial film, leading to increased droplet coalescence and phase separation. In contrast, the emulsion in the present invention showed a slower increase in IFT, rising from 5 mN/m to only 7.2 mN/m over the same 30 minutes period (Fig. 13). This gradual change suggests stronger interfacial film formation, which maintains emulsion integrity for a longer time.
Sesame oil demonstrated the highest stability, with the emulsion remaining stable for 5 days until equilibrium was reached, followed by soybean oil (2.4 hours), olive oil (1.5 hours), and synthetic ELM, which stabilized only for 20 minutes.
Advantage of Present Invention:
Enhancement in the emulsion stability.
Reduced Surfactant Requirement.
Improved Phase Separation Control.
Natural Additive Benefits (higher viscosity, stronger interfacial film formation, and antioxidant effects.
Reduced Environmental Impact.
Biocompatibility and Eco-friendly.
Simple operation for wastewater treatment application. , Claims:1. An edible oil-based bio-emulsion liquid membrane (Bio-ELM), wherein, the membrane comprises:
a membrane phase comprising of bio-diluents in a range from 90 to 98% v/v, surfactant in a range from 1 to 5 % v/v, carrier solvent in a range from 1 to 5 % v/v; and an internal aqueous phase.

2. The edible oil-based bio-emulsion liquid membrane as claimed in claim 1, wherein the bio-diluent is an edible oil selected from sesame oil, soybean oil and olive oil.

3. The edible oil-based bio-emulsion liquid membrane as claimed in claim 1, wherein the surfactant is a non-ionic surfactant selected from sorbitan monooleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monooleate, octylphenol ethoxylate, and sorbitan monolaurate.

4. The edible oil-based bio-emulsion liquid membrane as claimed in claim 1, wherein the carrier solvent is selected from xylene, toluene, heptane, pentane, and combinations thereof, preferably heptane.

5. The edible oil-based bio-emulsion liquid membrane as claimed in claim 1, wherein the internal aqueous phase comprises alkali hydroxides, preferably sodium hydroxide, ammonium hydroxide, and potassium hydroxide.

6. The edible oil-based bio-emulsion liquid membrane as claimed in claim 1, wherein Bio-ELM is having emulsion droplets of size in a range of 5 to 14 µm.

7. A process for synthesizing the edible oil-based bio-emulsion liquid membrane as defined in claim 1, wherein the process comprises steps of:
- adding surfactant, carrier solvent and bio-diluent to obtain a membrane phase;
- stirring the membrane phase to obtain a membrane phase mix;
- adding the internal aqueous phase drop by drop into the membrane phase mix; and
- stirring the membrane phase mix with internal aqueous phase to obtain the edible oil-based bio-emulsion liquid membrane.

8. The process as claimed in claim 7, wherein the surfactant, carrier solvent and bio-diluent are added in a percent ratio of 2:2:96 v/v.

9. The process as claimed in claim 7, wherein the stirring of membrane phase is carried out at 2000 rpm to 4000 rpm for 45 minutes to 75 minutes and wherein the stirring of membrane phase mix with the internal aqueous phase is carried out at 1000 rpm to 2000 rpm for 15 minutes to 25 minutes.

10. A method for extraction of pollutants from wastewater by contacting edible oil-based bio-emulsion liquid membrane as defined in claim 1 with the wastewater under continuous mixing at a pH in a range of 6 to 8.