Description:TECHNICAL FIELD
The present disclosure relates to water treatment using a triple interpenetrating polymer network (IPN) hydrogel designed for efficient removal of microplastics (MPs) from contaminated water. Specifically, the present disclosure relates to a method for synthesizing a triple interpenetrating polymer network hydrogel. Further, the present disclosure relates to a triple interpenetrating polymer network hydrogel composition.
BACKGROUND
Plastic and microplastic (MP) pollution pose significant environmental challenges globally, impacting ecosystems and public health. The persistent rise in plastic manufacturing, coupled with inadequate waste management, has led to the accumulation of plastic waste, particularly MPs, in water bodies. Reports indicate alarming levels of plastic dumping, contributing to the deterioration of marine environments and posing threats to aquatic life. In India, a surge in per capita plastic waste generation exacerbates the issue, emphasizing the urgent need for effective waste reduction strategies. The environmental impact of plastic pollution is further exacerbated by the leaching of harmful chemicals from plastics into food, beverages, and water, creating a health concern. The difficulty in treating end-of-life plastics, especially non-recyclable items like bags and cutlery, contributes to their persistence in the environment. The rise in medical waste, including surgical face masks, adds another dimension to microplastic pollution.
Existing technologies face limitations in addressing the diverse range of microplastics, including variations in density, composition, and environmental behaviour. The lack of effective methods for microplastic removal prompts the exploration of innovative solutions to mitigate environmental impact.
Therefore, in light of the foregoing discussion, there exists a need to overcome the aforementioned drawbacks.
SUMMARY
The present disclosure provides a method for synthesizing a triple interpenetrating polymer network hydrogel. The present disclosure addresses the technical problem of how to utilize a hydrogel efficiently and sustainably for the removal of microplastics from water bodies, expanding its applicability to water filtration processes. An aim of the present disclosure is to provide a solution that, at least partially, overcomes the challenges encountered in the prior art, presenting an improved method for enhancing microplastic capture. This innovative approach extends the utility of the hydrogel to water filtration, offering a versatile solution for the removal of particulate matter and impurities, thereby contributing to advancements in water treatment technologies.
One or more objectives of the present disclosure is achieved by the solutions provided in the enclosed independent claims. Advantageous implementations of the present disclosure are further defined in the dependent claims.
In one aspect, the present disclosure provides a method for synthesizing a triple interpenetrating polymer network hydrogel. The method comprising: performing mixing of a polyvinyl alcohol (PVA) solution, a chitosan (CS) solution, and a copper-polyoxometalate (Cu-POM) solution to obtain a first mixture; blending an aniline monomer doped with hydrochloric acid into the first mixture; forming a porous hydrogel with a triple interpenetrating polymer network (IPN) structure by performing a sequential interpenetrating polymerization of the doped aniline monomer mixed in the first mixture in presence of a chemical initiator for polymerization of the doped aniline monomer into polyaniline and to the IPN structure; and adding a cross-linking agent into the porous hydrogel to form a cross-linked network within the porous hydrogel suited to adsorb microplastics from a water sample.
In response to the challenges posed by microplastic pollution, the present invention introduces the triple interpenetrating polymer network (IPN) hydrogel designed for efficient microplastic removal in water treatment. The hydrogel's unique architecture incorporates a polymer network of Polyvinyl Alcohol (PVA), Chitosan (CS), and Polyaniline (PANI) in a triple interpenetrating structure, ensuring mechanical robustness for real-world applications.
To enhance the hydrogel's efficacy, a novel copper-substituted polyoxometalate (Cu-POM) nanocluster is in-situ decorated within the hydrogel. This addition not only improves the adsorption capabilities of the hydrogel but also contributes to its responsiveness to external stimuli such as pH or temperature, allowing controlled pollutant release or regeneration.
The hydrogel's triple IPN structure, coupled with the Cu-POM nanocluster, provides a versatile and selective approach to microplastic removal. Its tunable porosity, large surface area, and high adsorption capacity make it suitable for capturing and retaining microplastics efficiently. The hydrogel's responsiveness to environmental conditions ensures long-term use and sustainability, offering a multifaceted solution to the challenges of water pollution and environmental conservation. In conclusion, the present disclosure addresses the critical need for an efficient and sustainable method for microplastic removal, contributing to the broader goal of environmental preservation and water quality improvement.
In another aspect, the present disclosure provides a triple interpenetrating polymer network hydrogel composition that comprises one part by weight of polyvinyl alcohol, one part by weight of chitosan, half part by weight of polyaniline, and half part by weight of copper-polyoxometalate.
The triple interpenetrating polymer network hydrogel composition of the present disclosure has same technical effects as described above for the method. For example, the triple interpenetrating polymer network hydrogel demonstrates improved adsorption capacity, mechanical robustness, and responsiveness to external stimuli, making it highly efficient in the selective removal of microplastics from water samples.
It is to be appreciated that all the aforementioned implementation forms can be combined. All steps which are performed by the various entities described in the present application as well as the functionalities described to be performed by the various entities are intended to mean that the respective entity is adapted to or configured to perform the respective steps and functionalities. It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.
Additional aspects, advantages, features and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative implementations construed in conjunction with the appended claims that follow.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a flowchart depicting a method for synthesizing a triple interpenetrating polymer network hydrogel, in accordance with an embodiment of the present disclosure;
FIGs. 2A-2D collectively depicts a flow diagram of the method for synthesizing the triple interpenetrating polymer network hydrogel, in accordance with an embodiment of the present disclosure;
FIG. 2E is a photograph of the triple interpenetrating polymer network hydrogel, in accordance with an embodiment of the present disclosure;
FIG. 2F is an enlarged schematic diagram of the triple interpenetrating polymer network hydrogel, in accordance with an embodiment of the present disclosure;
FIG. 3A is a chemical structure of the triple interpenetrating polymer network hydrogel, in accordance with an embodiment of the present disclosure;
FIG. 3B is a scanning electron microscope photograph of the triple interpenetrating polymer network hydrogel, in accordance with an embodiment of the present disclosure;
FIG. 4 is a schematic diagram depicting photodegradation of microplastics disposed in the triple interpenetrating polymer network hydrogel, in accordance with an embodiment of the present disclosure;
FIG. 5A is an exemplary graphical representation depicting percentage removal of microplastics per cycle from a water sample using the triple interpenetrating polymer network hydrogel, in accordance with an embodiment of the present disclosure;
FIG. 5B is an exemplary graphical representation depicting a variation in a percentage removal of microplastics using the triple interpenetrating polymer network hydrogel in solutions having various pH, in accordance with an embodiment of the present disclosure; and
FIG. 5C is an exemplary graphical representation depicting a variation in a percentage removal of microplastics using various hydrogels, in accordance with an embodiment of the present disclosure.
The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those skilled in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.
Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:
In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.
DETAILED DESCRIPTION OF EMBODIMENTS
The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognize that other embodiments for carrying out or practicing the present disclosure are also possible.
FIG. 1 is a flowchart depicting a method for synthesizing a triple interpenetrating polymer network hydrogel, in accordance with an embodiment of the present disclosure. With reference to FIG. 1, there is shown a flowchart of a method 100. In some implementations, the method 100 is executed by a skilled person. The method 100 may include steps 102 to 108.
There is provided the method 100 for synthesizing a triple interpenetrating polymer network (IPN) hydrogel, the triple IPN hydrogel is a unique three-dimensional structure composed of interconnected polymer networks within a hydrogel matrix. A hydrogel is gel-like material primarily composed of water and polymer chains. Hydrogels are known for their high water absorption capacity, flexibility, and biocompatibility. A triple network structure of the triple IPN hydrogel includes polyvinyl alcohol (PVA), chitosan (CS), and polyaniline (PANI) interconnected with copper-polyoxometalate (Cu-POM), that imparts unique properties to the triple IPN hydrogel. This configuration enhances the mechanical robustness of the triple IPN hydrogel, making it well-suited for real-world applications. The incorporation of Cu-POM nanoclusters further enhances its adsorption capabilities, particularly for microplastics (MP) in water samples. The triple IPN hydrogel's tunable porosity and large surface area enable efficient physical and chemical adsorption of pollutants. Additionally, the cross-linked network formed during synthesis contributes to structural stability, ensuring durability in various environmental conditions. The triple IPN hydrogel's responsiveness to external stimuli, such as pH or temperature changes, allows for controlled pollutant release or regeneration, extending its usability. Overall, the triple interpenetrating polymer network hydrogel presents a multifaceted and sustainable solution for pollutant removal, highlighting advantages in terms of efficacy, versatility, and environmental applicability. The term “microplastics” refers to tiny particles of plastic material, typically measuring less than 5 millimetres (mm) in size. These minuscule plastic fragments result from the breakdown of larger plastic items through processes like weathering, photodegradation, and mechanical abrasion. Microplastics can also enter the environment in smaller forms, such as microbeads used in personal care products or as pellets in industrial processes. The term “nanocluster” refers to a small, well-defined assembly of nanoparticles that are grouped together, often exhibiting unique properties and behaviours due to their nanoscale dimensions and specific arrangement. Nanoclusters can consist of a few to several hundred nanoparticles, forming a cluster with a size typically ranging from about 1 to 10 nanometres (nm).
At step 102, the method 100 includes performing mixing of a polyvinyl alcohol (PVA) solution, a chitosan (CS) solution, and a copper-polyoxometalate (Cu-POM) solution to obtain a first mixture. Each solution contributes distinct properties to the hydrogel, making the mixing process essential for achieving a synergistic combination of these components. PVA, a water-soluble synthetic polymer, forms the matrix of the hydrogel, providing mechanical strength and water absorption capacity. Chitosan, a natural biopolymer, enhances biocompatibility and introduces positive charges under acidic conditions, contributing to the hydrogel's structure and potential interaction with charged substances. The incorporation of Cu-POM, a nanocluster material, introduces unique functionality, particularly enhancing the hydrogel's photodegradation capabilities. The mixing ensures homogeneity, allowing for a uniform distribution of each component in the first mixture.
In some implementations, the PVA solution is obtained by performing mixing and stirring of 3-5 % w/w of polyvinyl alcohol with 95-97% w/w of the de-ionized water. Specifically, in some examples, the PVA at a concentration of 3.85% w/w may be blended with 96% w/w deionized (DI) water. The resulting mixture underwent stirring at a rotational speed ranging from 400 to 600 rpm, maintaining a temperature of 50 to 90 degrees Celsius for a duration of 4 to 6 hours. In some implementations, the CS solution is obtained by performing mixing and agitating of 2% w/w chitosan with 98% w/w of an aqueous acetic acid solution. Specifically, in some examples, CS flakes, constituting 2% w/w, may be introduced into a distinct container. Subsequently, a 98% w/w aqueous acetic acid solution (with a 2% v/v concentration) may be added to the container. The resulting mixture underwent agitation for a duration of 4 to 8 hours at a temperature of 40 to 80 degree Celsius.
In some implementations, the Cu-POM solution is obtained by performing mixing and probe-sonication of 9-10% w/w of copper-polyoxometalate with 90-91% w/w of de-ionized water. In some examples, the copper-polyoxometalate is a Kegging-type copper-polyoxometalate. In such examples, the Kegging-type Copper-polyoxometalate (Cu-POM) may be synthesized through a meticulous hydrothermal process. In such process, copper sulphate pentahydrate (CuSO4·5H2O) was dissolved in deionized water (DI water), forming the copper precursor. Simultaneously, molybdenum trioxide hydrate (MoO3·H2O), ethylene diamine, and phosphoric acid (H3PO4) may be added to the solution. Thorough mixing via a magnetic stirrer ensured a homogeneous distribution of these components. The resulting mixture was then subjected to a Teflon-lined autoclave and treated hydrothermally at 180 to 220 degrees Celsius for 72 hours. After hydrothermal processing, the precipitate was separated through centrifugation, followed by rinsing with DI water to eliminate impurities. The final step involved oven-drying the rinsed precipitate to obtain the Cu-POM powder. This synthesis process allows for the controlled formation of the Kegging-type Cu-POM, demonstrating a systematic approach to producing the desired polyoxometalate material.
At step 104, the method 100 further includes blending an aniline monomer doped with hydrochloric acid into the first mixture. The aniline monomer is a key component in the formation of polyaniline (PANI), a conductive polymer known for its versatile applications. The doping process involves introducing hydrochloric acid to aniline, resulting in the formation of a doped aniline monomer. This blending step ensures that the aniline monomer is uniformly distributed within the mixture, facilitating its subsequent polymerization and integration into the evolving hydrogel network. The doped aniline brings specific chemical characteristics to the hydrogel, influencing its final properties and making it suitable for applications such as pollutant adsorption. In some examples, the first mixture after mixing the aniline monomer doped with hydrochloric acid may be blended for an additional 6 to 8 hrs. to ensure the uniform blending of the first mixture.
At step 106, the method 100 further includes forming a porous hydrogel with a triple IPN structure by performing a sequential interpenetrating polymerization of the doped aniline monomer mixed in the first mixture in presence of a chemical initiator for polymerization of the doped aniline monomer into polyaniline and to the triple IPN structure. In some implementations, the porous hydrogel with the triple IPN structure is a Cu-POM nanocluster-infused triple IPN hydrogel. The objective of this step is to create the porous hydrogel with the triple IPN structure, characterized by the simultaneous presence of three interpenetrating polymer networks – polyvinyl alcohol (PVA), chitosan (CS), and polyaniline (PANI). This unique architecture enhances the hydrogel's mechanical strength, stability, and adsorption capabilities. The triple IPN structure is designed to optimize the triple IPN hydrogel's performance, making it well-suited for real-world applications, particularly in the context of microplastic (MP) capture from water or a water sample. Each polymer network contributes distinct properties – PVA provides mechanical strength, CS enhances biocompatibility, and PANI introduces conductivity and adsorption capacity. The term “sequential interpenetrating polymerization” refers to process in polymer chemistry where two or more polymerization reactions occur consecutively or in a stepwise manner to produce a material with interpenetrating polymer networks (IPNs). In some examples, the sequential interpenetrating polymerization involves the successive polymerization of different monomers to form distinct polymer networks within the triple IPN hydrogel. The sequential nature of the interpenetrating polymerization allows for a controlled and organized buildup of the polymer networks, ensuring their integration and interpenetration throughout the hydrogel structure. This results in a porous framework with enhanced surface area, providing ample sites for the adsorption of microplastics. In some implementations, the sequential semi-interpenetrating polymerization includes polymerization of aniline to polyaniline with addition of an equimolar ammonium persulfate (APS) aqueous solution in an ice bath condition for 10-15 hours. In some implementations, the chemical initiator is the APS aqueous solution.
In some implementations, the method 100 includes incorporating the Cu-POM into a Metal-Organic Framework (MOF) forming Polyoxometalate-based Metal-Organic Framework (POMOF) which is then integrated within in the triple IPN structure of the porous hydrogel. In such implementation, the incorporation of Cu-POM into a Metal-Organic Framework (MOF) to form Polyoxometalate-based Metal-Organic Framework (POMOF), followed by its integration within the triple interpenetrating polymer network (IPN) structure of the porous hydrogel, serves to enhance the hydrogel's efficacy in removing microplastics from water. This strategic integration brings forth a combination of unique properties and synergistic effects. Cu-POM, known for its distinctive adsorption capabilities, is enriched by its inclusion in a MOF, amplifying its selective adsorption properties. The resulting POMOF, when seamlessly integrated into the hydrogel's triple IPN structure, contributes to the creation of a versatile and adaptable material. This tailored composition not only improves the hydrogel's adsorption efficiency but also imparts responsiveness to environmental conditions. The adaptability of the hydrogel to specific contaminants, particularly microplastics, is optimized through the synergistic effects of Cu-POM and MOF. Ultimately, this innovative integration aims to provide a smart and efficient solution for the targeted removal of microplastics, offering a versatile tool for addressing the challenges posed by water pollution.
At step 108, the method 100 further includes adding a cross-linking agent into the porous hydrogel to form a cross-linked network within the porous hydrogel suited to adsorb microplastics from a water sample. In some implementations, the cross-linking agent is one of: glutaraldehyde (GA) or sodium tri-metaphosphate (STMP). The incorporation of a cross-linking agent, such as aqueous glutaraldehyde (GA) or sodium tri-metaphosphate (STMP) is essential to establish covalent bonds between polymer chains within the hydrogel. This process results in the formation of a robust and three-dimensional cross-linked network. The primary objective is to provide mechanical stability to the porous structure of the hydrogel, ensuring its durability and preventing degradation during water treatment applications. The cross-linked network acts as a protective matrix, reinforcing the hydrogel's structure against external forces and maintaining its porous architecture. This reinforcement is vital for the hydrogel to withstand the challenges posed by water environments while retaining its optimal adsorption capabilities. In some implementations, the cross-linking process serves as a barrier, preventing leaching of components from the hydrogel into the water. This ensures that the hydrogel remains effective in adsorbing microplastics without introducing undesirable substances into the treated water. Additionally, the cross-linked structure mitigates the risk of hydrogel breakdown over time, contributing to its long-term stability. By creating the cross-linked network, the hydrogel's surface area is enhanced, providing an increased number of sites for the physical and chemical adsorption of microplastics. This optimization is critical for maximizing the hydrogel's efficiency in capturing and retaining microplastic particles from diverse water samples.
Advantageously, the cross-linking agent not only reinforces the hydrogel but also imparts durability, allowing the hydrogel to maintain its effectiveness over extended periods of use. This characteristic is particularly advantageous for practical applications where the hydrogel needs to endure various environmental conditions and be reusable for multiple treatment cycles.
In some implementations, the adding of the cross-linking agent includes adjusting an average pore size of a plurality of pores of the cross-linked network within the triple IPN hydrogel, based on an amount of the cross-linking agent added to the porous hydrogel. In other words, the incorporation of the cross-linking agent allows for precise control over the average pore size within the cross-linked network of the triple IPN hydrogel. This adjustment is crucial because the size of microplastics in water samples can vary significantly. By modulating the pore size, the hydrogel can be tailored to effectively capture microplastics of diverse dimensions. Larger pores accommodate larger microplastics, while smaller pores enhance the adsorption of smaller particles. This adaptability ensures that the hydrogel's adsorption capacity is optimized for a wide range of microplastic sizes, contributing to its versatility in water treatment applications.
In some implementations, the amount of the cross-linking agent added into the porous hydrogel depends on a size and a concentration of microplastics in a water sample to be treated. In other words, the amount of the cross-linking agent added to the porous hydrogel is intricately linked to the size and concentration of microplastics in the water sample intended for treatment. Larger concentrations or sizes of microplastics may require a higher degree of cross-linking to fortify the hydrogel structure and prevent saturation. Conversely, for lower concentrations or smaller microplastics, a more moderate amount of cross-linking may suffice. This adaptive approach ensures that the hydrogel is efficiently utilized based on the specific characteristics of the microplastics present in the water, enhancing its overall effectiveness.
Beneficially, optimizing the cross-linking agent's amount based on microplastic characteristics not only enhances adsorption efficiency but also contributes to the hydrogel's structural stability. A well-calibrated cross-linked network withstands the challenges posed by different microplastic sizes and concentrations, promoting the hydrogel's longevity and reusability. This is particularly important for practical applications where the hydrogel undergoes repeated treatment cycles in varying environmental conditions.
In some other implementations, the method 100 includes causing photodegradation of the adsorbed microplastics at a surface of the porous hydrogel due to embedded Cu-POM nanocluster in the porous hydrogel. Photodegradation provides an extra layer of effectiveness in breaking down the chemical structure of adsorbed microplastics. Specifically, the photodegradation is employed to harness the power of sunlight as well as under an ultraviolet (UV) light in breaking down the chemical structure of adsorbed microplastics on the surface of the hydrogel. This supplementary mechanism complements the physical adsorption and chemical interactions occurring within the triple IPN hydrogel. By subjecting the adsorbed microplastics to photodegradation, the aim is to facilitate the breakdown of larger plastic particles into smaller fragments. This transformation may render the microplastics more amenable to subsequent natural degradation processes, potentially reducing their persistence in the environment. The Cu-POM nanoclusters embedded in the porous hydrogel exhibit photocatalytic properties, generating reactive species under sunlight or UV light exposure. The presence of these reactive species enhances the breakdown of the microplastics, creating a synergistic effect with the inherent properties of the nanoclusters. Moreover, the three-dimensional interpenetrating polymer network (IPN) structure of the hydrogel provides an ideal matrix for the stable incorporation and distribution of Cu-POM nanoclusters. This ensures uniform exposure of the nanoclusters to sunlight and UV light sources, optimizing the efficiency of the photodegradation process. In essence, the incorporation of photodegradation in the method 100 reflects a commitment to environmental friendliness and a comprehensive approach to microplastic remediation. By utilizing light to facilitate the breakdown of microplastics, the method seeks to contribute to the broader efforts aimed at mitigating the impact of microplastic pollution in water samples and promoting sustainable water treatment practices.
In another implementation, the method 100 includes upcycling spent hydrogel including absorbed microplastics into carbon nanoparticles via a hydrothermal process. The spent hydrogel corresponds to the porous hydrogel with the cross-linked network that has adsorbed the microplastics present in water for a defined duration. In such implementation, the spent hydrogel, having fulfilled its primary role in adsorbing microplastics, is repurposed to extract additional value. This aligns with the principle of resource efficiency, ensuring that materials are utilized to their fullest potential before reaching the end of their life cycle. By transforming the spent hydrogel into the carbon nanoparticles, the method 100 embraces the concept of a circular economy. Rather than discarding the triple IPN hydrogel as waste, it undergoes a secondary use, reducing the overall environmental impact and promoting a closed-loop system. The hydrothermal process mentioned above involves subjecting the spent hydrogel to elevated temperatures and pressures in the presence of water. This controlled environment facilitates the carbonization of the hydrogel, leading to the formation of carbon nanoparticles. During hydrothermal treatment, the organic components of the spent hydrogel undergo carbonization, resulting in the formation of carbonaceous structures. This transformation is fundamental to the generation of carbon nanoparticles with unique properties. The carbon nanoparticles obtained from the hydrothermal process are repurposed as an adsorbent. In some examples, the carbon nanoparticles demonstrate exceptional efficiency in removing heavy metal chromium (Cr (VI)) from contaminated water. This highlights the versatility of the upcycled material in addressing different environmental challenges. The reuse of carbon nanoparticles for water treatment exemplifies a sustainable approach. It not only addresses microplastic pollution but extends the environmental benefit by tackling heavy metal contamination, contributing to overall water quality improvement.
In yet another implementation, the cross-linked network within the porous hydrogel refers to PVA-Chitosan- polyaniline polymer networks. In such implementation, the PVA-Chitosan-polyaniline polymer network includes the PVA, the chitosan, the polyaniline (PANI), and the Cu-POM in a proportionate ratio of 1:1:0.5:0.5. In other words, a triple interpenetrating polymer network hydrogel composition includes one part by weight of polyvinyl alcohol, one part by weight of chitosan, half part by weight of polyaniline, and half part by weight of copper-polyoxometalate.
In some implementations, the method 100 further includes affixing the porous hydrogel with the cross-linked network on a substrate and disposing within a water body to allow the cross-linked network within the porous hydrogel to serve as a microplastic entrapment apparatus. The microplastics are captured within the plurality of pores created by the cross-linked network. Affixing the porous hydrogel with the cross-linked network on a substrate provides structural support and stability. This arrangement allows the hydrogel to effectively serve as a microplastic entrapment apparatus by leveraging its porous structure. The cross-linked network within the hydrogel creates a multitude of pores, enhancing the capacity to capture and retain microplastics present in water bodies. The substrate serves as a platform for strategically placing the hydrogel in water bodies. This ensures a spatial distribution that maximizes exposure to areas prone to microplastic contamination. The affixed hydrogel, with its tailored triple interpenetrating polymer network (IPN) structure, offers an efficient and targeted approach for microplastic entrapment. By disposing the hydrogel within a water body, the method facilitates a long-term solution for microplastic capture. The cross-linked network's durability ensures that the hydrogel remains effective over extended periods, providing a sustainable and continuous entrapment apparatus. In some examples, the substrate-affixed hydrogel can be deployed in water treatment plants, especially in areas where microplastic contamination is a significant concern. The hydrogel can serve as an additional filtration step to enhance the removal of microplastics from treated water. In another example, deploying the hydrogel in rivers, lakes, or other natural water bodies can help mitigate the impact of microplastics on aquatic ecosystems. The substrate-bound hydrogel can act as a targeted solution in areas prone to pollution. In yet another example, placing the hydrogel near industrial outflows or areas with high human activity may assist in capturing microplastics before they disperse into the broader environment. This proactive approach contributes to pollution prevention.
FIGs. 2A-2D collectively depicts a flow diagram of the method for synthesizing the triple interpenetrating polymer network hydrogel, in accordance with an embodiment of the present disclosure. With reference to FIGs. 2A-2D, there is a flow diagram 200 for synthesizing the triple interpenetrating polymer network hydrogel. Initially, in FIG. 2A, the PVA solution, the CS solution, and the Cu-POM solution are combined together in a beaker to produce a homogeneous mixture. Subsequently, 1-2 ml of Hydrochloric doped aniline monomer are mixed the homogenous mixture of the PVA solution, the CS solution, and the Cu-POM solution. Further, the solutions are stirred on a magnetic stirrer as shown in FIG. 2A at 70 degrees Celsius for 6 to 7 hours. Further, in FIG. 2B, a chemical initiator is added to the beaker in an ice bath condition for 10-15 hours to initiate polymerization. The chemical initiator is the APS aqueous solution. Furthermore, in FIG. 2C, the cross linking agent is added to the prepared mixture. In this case, the glutaraldehyde (GA) is used as the cross linking agent. Lastly, in FIG. 2D, the prepared solution is dried in a Petridis at 25 degrees Celsius.
FIG. 2E is a photograph of the triple interpenetrating polymer network hydrogel, in accordance with an embodiment of the present disclosure. With reference to FIG. 2E, there is shown a photograph 204 of the triple interpenetrating polymer network hydrogel.
FIG. 2F is an enlarged schematic diagram of the triple interpenetrating polymer network hydrogel, in accordance with an embodiment of the present disclosure. With reference to FIG. 2E, there is shown an enlarged schematic diagram 206 of the triple interpenetrating polymer network hydrogel. The enlarged schematic diagram 206 shows entanglement of multiple polymers such as PVA polymer chains 208, CS polymer chains 210, and polyaniline polymer chains 212. The enlarged schematic diagram 206 further shows one or more Cu-POM crystals 214 entangled in the PVA polymer chains 208, the CS polymer chains 210, and the polyaniline polymer chains 212. Further, empty or vacant spaces in between the entanglement of the PVA polymer chains 208, the CS polymer chains 210, and the polyaniline polymer chains 212 represents one or more pores 216 of the triple interpenetrating polymer network hydrogel, as shown by dotted circles in FIG. 2F.
FIG. 3A is a chemical structure of the triple interpenetrating polymer network hydrogel, in accordance with an embodiment of the present disclosure. With reference to FIG. 3A, there is shown a chemical structure 300 of the triple interpenetrating polymer network hydrogel. The chemical structure 300 reveals the interwoven networks of Polyvinyl alcohol (PVA), Chitosan (CS), and Polyaniline (PANI), forming a robust and interconnected three-dimensional matrix. The intricate arrangement of these polymers contributes to the hydrogel's unique properties, including high water absorption capacity, tunable porosity, and mechanical strength. Additionally, the incorporation of Copper-polyoxometalate (Cu-POM) nanoclusters is integral to the hydrogel's enhanced functionality, particularly in the removal of microplastics from water sources. The triple IPN structure is designed to provide optimal performance in water treatment applications, highlighting the versatility and effectiveness of the developed hydrogel.
FIG. 3B is a scanning electron microscope (SEM) photograph of the triple interpenetrating polymer network hydrogel, in accordance with an embodiment of the present disclosure. With reference to FIG. 3A, there is shown a SEM photograph 302 of the triple interpenetrating polymer network hydrogel. The term “scanning electron microscope photograph” to an image captured using a scanning electron microscope. Scanning electron microscope is a powerful microscopy technique that uses electrons to create detailed images of the surface morphology of specimens at an extremely high resolution. The SEM photograph 302 reveals an intricate structure of the triple IPN hydrogel, highlighting a presence of a plurality pores 304 and surface features that resemble cracks on a rough surface. The plurality of pores 304, depicted in high resolution, are a key aspect of the hydrogel's design, contributing to its high adsorption capacity and effectiveness in capturing microplastics from water sources. Each of the plurality of pores 304 has an average pore size 306 that may be adjusted based on an amount of the cross linking agent added while synthesis on the triple IPN hydrogel and based on size of the microplastics being removed. The rough surface texture observed in the SEM photograph 302 enhances the hydrogel's surface area, providing ample sites for physical and chemical interactions with pollutants. This SEM analysis further validates the robust and porous nature of the triple IPN hydrogel, highlighting its suitability for real-world applications in water treatment and microplastic capture.
FIG. 4 is a schematic diagram depicting photodegradation of microplastics disposed in the triple interpenetrating polymer network hydrogel, in accordance with an embodiment of the present disclosure. With reference to FIG. 4, there is shown a schematic diagram 400 depicting photodegradation of microplastics disposed in a triple interpenetrating polymer network hydrogel 402. Further, the triple interpenetrating polymer network hydrogel 402 is exposed to a light coming from a light source 404. In the illustrated embodiment of FIG. 4, the light source 404 is the sun and the light is sunlight or the UV light. However, in some other embodiments, the light source 404 may include the UV light source or any other light source as per application requirement and availability. The schematic diagram 400 visually represents the crucial mechanism by which the triple IPN hydrogel 402 facilitates the breakdown of microplastics. This process is initiated by exposure to light, specifically utilizing the embedded Cu-POM nanocluster within the triple IPN hydrogel 402. As depicted, the microplastics, symbolized within the hydrogel structure, undergo photodegradation upon exposure to light. The embedded Cu-POM nanocluster plays a pivotal role in this photodegradation process, potentially enhancing the efficiency of microplastic breakdown. In some implementations, the triple IPN hydrogel 402 facilitates the breakdown of polyvinyl chloride (PVC) microplastics 406 and polypropylene (PP) microplastics 408. In some other implementations, the triple IPN hydrogel 402 may facilitate the breakdown of other types of microplastics, including but not limited to polyvinyl chloride (PVC) microplastics and polypropylene (PP) microplastics. The unique properties of the triple IPN hydrogel 402 make it versatile in addressing various types of microplastics present in different environmental settings. By leveraging its triple IPN structure, the triple IPN hydrogel 402 demonstrates efficacy in facilitating the breakdown of diverse microplastic materials, highlighting its adaptability and potential application across a broad spectrum of environmental conditions.
FIG. 5A is an exemplary graphical representation depicting percentage removal of microplastics from a water sample per usage cycle of the triple interpenetrating polymer network hydrogel, in accordance with an embodiment of the present disclosure. With reference to FIG. 5A, there is shown a graphical representation 500A depicting percentage removal of microplastics from a water sample per usage cycle of the triple interpenetrating polymer network hydrogel. Each cycle represents a specific period or instance of hydrogel application in water treatment. An x-axis of the graphical representation 500A represents number of treatment cycles, ranging from the 1st cycle to the 6th cycle. In other words, the x axis represents a variable associated with the number of usage cycles performed using the triple IPN hydrogel. The corresponding y-axis (ordinate) represent the percentage removal of PVC microplastics and PP microplastics, showing how this removal efficiency varies over different treatment cycles. The graphical representation 500A demonstrates that the triple IPN hydrogel exhibits maximum efficiency in the 1st cycle, gradually diminishing in subsequent cycles. This observed trend indicates a reduction in the hydrogel's efficacy for microplastic removal over successive treatment cycles.
FIG. 5B is an exemplary graphical representation depicting a variation in a percentage removal of microplastics using the triple interpenetrating polymer network hydrogel in solutions having various pH, in accordance with an embodiment of the present disclosure. With reference to FIG. 5B, there is shown a graphical representation 500B illustrating a variation in percentage removal of microplastics (MP) using the triple IPN hydrogel across solutions with different pH levels. The x-axis represents the pH values of the solutions, while the y-axis denotes the corresponding percentage removal of PVC microplastics and PP microplastics. The graphical representation 500B aims to highlight the triple IPN hydrogel's performance under varying pH conditions. The triple IPN hydrogel demonstrated remarkable microplastic removal efficiency, ranging from 78.8% to 95.5% for PVC microplastics and 83.5% to 93.3% for PP microplastics, within a solution pH range of 2.5 to 6.5. However, a notable decline in removal efficiency is observed as the solution pH exceeded 7 and approached 12. Analyzing the data provides insights into the hydrogel's efficacy in microplastic removal across a range of pH values, contributing valuable information for potential applications in diverse environmental settings.
FIG. 5C is an exemplary graphical representation depicting a variation in a percentage removal of microplastics using various hydrogels, in accordance with an embodiment of the present disclosure. With reference to FIG. 5C, there is shown a graphical representation 500C depicting a variation in a percentage removal of microplastics using three different hydrogels. The x-axis represents the various hydrogels, while the y-axis denotes the corresponding percentage removal of PVC microplastics and PP microplastics. The three hydrogels includes a IPN hydrogel (HG@IPN), a hydrogel (POM-HG@IPN) incorporating polyoxometalate (POM) within its structure as part of an interpenetrating polymer network, and a hydrogel (POMOF-HG@IPN) where the polyoxometalate-based metal-organic framework (MOF) is integrated into the interpenetrating polymer network. As illustrated in FIG. 5C, the graphical representation 500C demonstrates impressive capabilities of both the POM-HG@IPN and the POMOF-HG@IPN in effectively adsorbing microplastics. Inclusion of the POMOF nanocluster in the hydrogel increase the photodegradation effectiveness of adsorbed microplastics on the hydrogel matrix, leveraging the synergistic benefits of MOF and POM catalysts.
Modifications to embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as "including", "comprising", "incorporating", "have", "is" used to describe and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural. The word "exemplary" is used herein to mean "serving as an example, instance or illustration". Any embodiment described as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments and/or to exclude the incorporation of features from other embodiments. The word "optionally" is used herein to mean "is provided in some embodiments and not provided in other embodiments". It is appreciated that certain features of the present disclosure, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the present disclosure, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable combination or as suitable in any other described embodiment of the disclosure. , Claims:1. A method (100) for synthesizing a triple interpenetrating polymer network hydrogel, the method (100) comprising:
performing (102) mixing of a polyvinyl alcohol (PVA) solution, a chitosan (CS) solution, and a copper-polyoxometalate (Cu-POM) solution to obtain a first mixture;
blending (104) an aniline monomer doped with hydrochloric acid into the first mixture;
forming (106) a porous hydrogel with a triple interpenetrating polymer network (IPN) structure by performing a sequential interpenetrating polymerization of the doped aniline monomer mixed in the first mixture in presence of a chemical initiator for polymerization of the doped aniline monomer into polyaniline and to the triple IPN structure; and
adding (108) a cross-linking agent into the porous hydrogel to form a cross-linked network within the porous hydrogel suited to adsorb microplastics from a water sample.
2. The method (100) as claimed in claim 1, wherein the adding of the cross-linking agent comprises adjusting an average pore size (306) of a plurality of pores (304) of the cross-linked network within the triple IPN hydrogel, based on an amount of the cross-linking agent added to the porous hydrogel.
3. The method (100) as claimed in claim 2, wherein the amount of the cross-linking agent added into the porous hydrogel depends on a size and a concentration of microplastics in a water sample to be treated.
4. The method (100) as claimed in claim 2, wherein the method (100) further comprises affixing the porous hydrogel with the cross-linked network on a substrate and disposing within a water body to allow the cross-linked network within the porous hydrogel to serve as a microplastic entrapment apparatus, wherein the microplastics are captured within the plurality of pores (306) created by the cross-linked network.
5. The method (100) as claimed in claim 1, wherein the PVA solution is obtained by performing mixing and stirring of 3-5 % w/w of polyvinyl alcohol with 95-97% w/w of the de-ionized water.
6. The method (100) as claimed in claim 1, wherein the CS solution is obtained by performing mixing and agitating of 2% w/w chitosan with 98% w/w of an aqueous acetic acid solution.
7. The method (100) as claimed in claim 1, wherein the Cu-POM solution is obtained by performing mixing and probe-sonication of 9-10% w/w of copper-polyoxometalate with 90-91% w/w of de-ionized water.
8. The method (100) as claimed in claim 1, wherein the method (100) comprises causing photodegradation of the adsorbed microplastics at a surface of the porous hydrogel due to embedded Cu-POM nanocluster in the porous hydrogel, wherein the porous hydrogel with the triple IPN structure is a Cu-POM nanocluster-infused triple IPN hydrogel.
9. The method (100) as claimed in claim 1, wherein the method (100) comprises upcycling spent hydrogel comprising absorbed microplastics into carbon nanoparticles via a hydrothermal process, wherein the spent hydrogel corresponds to the porous hydrogel with the cross-linked network that has adsorbed the microplastics present in water for a defined duration.
10. The method (100) as claimed in claim 1, wherein the cross-linked network within the porous hydrogel refers to PVA-Chitosan- polyaniline polymer networks.
11. The method (100) as claimed in claim 10, wherein the PVA-Chitosan-polyaniline polymer network comprises the PVA, the chitosan, the polyaniline (PANI), and the Cu-POM in a proportionate ratio of 1:1:0.5:0.5.
12. The method (100) as claimed in claim 1, wherein the sequential semi-interpenetrating polymerization comprises polymerization of aniline to polyaniline with addition of an equimolar ammonium persulfate (APS) aqueous solution in an ice bath condition for 10-15 hours, wherein the chemical initiator is the APS aqueous solution.
13. The method (100) as claimed in claim 1, wherein the cross-linking agent is one of: glutaraldehyde (GA) or sodium tri-metaphosphate (STMP).
14. The method (100) as claimed in claim 1, wherein the method (100) comprises incorporating the Cu-POM into a Metal-Organic Framework (MOF) forming Polyoxometalate-based Metal-Organic Framework (POMOF) which is then integrated within in the triple IPN structure of the porous hydrogel.
15. A triple interpenetrating polymer network hydrogel composition comprising:
one part by weight of polyvinyl alcohol;
one part by weight of chitosan;
half part by weight of polyaniline; and
half part by weight of copper-polyoxometalate.