A Rotating Electrochemical Reactor Using Boron-doped Diamond and Titanium Electrodes for Degrading Polystyrene Microplastics, and Method Thereof

Abstract

Disclosed herein is a Rotating Electrochemical Reactor (RECR) for efficient degradation of polystyrene microplastics (PS-MPs) in water. The reactor uses Boron-Doped Diamond (BDD) anodes and titanium cathodes. This reactor minimizes anode fouling by rotating the anodes, which enhances mass transfer and reduces ohmic resistance in the electrochemical cell. This rotation disrupts bubble accumulation on the electrode surface, thereby ensuring a continuous and efficient electro-oxidation process. The Boron-Doped Diamond anodes generate highly reactive oxidative radicals, which directly attack PS-MPs, breaking them down into less complex and environmentally safe compounds without producing toxic by-products. This method offers a scalable, eco-friendly approach to addressing MP pollution in wastewater treatment applications, with potential for integration into larger water remediation systems.

Specification

Description:A Rotating Electrochemical Reactor Using Boron-doped Diamond and Titanium Electrodes for Degrading Polystyrene Microplastics, and Method Thereof
Field of the Invention
The present invention relates to an electrochemical reactor. More particularly, the present invention relates to rotational electrochemical reactor for a wastewater effluent treatment plant.
Background of the Invention
The environmental persistence of microplastics (MPs) in water systems has become a pressing issue due to the limitations of traditional separation and filtration technologies. Over time, numerous methods have been developed to separate MPs from wastewater, such as disc filtration, rapid sand filtration, dissolved air flotation, membrane bioreactors (MBR), ultrafiltration, dynamic membrane filtration, and electrocoagulation. Although effective in filtering and reducing MPs in wastewater treatment plants (WWTPs), these methods often fail to remove MPs completely, leading to ongoing release into natural water systems. Moreover, they largely function through separation rather than degradation, meaning MPs remain in a non-degraded, potentially harmful state. The need for alternative solutions that actively degrade MPs, rather than simply removing them from water, has become increasingly clear, highlighting a gap in existing technologies.
Researchers have also explored the possibility of degrading MPs rather than merely separating them from water. For instance, photocatalytic degradation has shown potential, yet studies indicate that it requires extended periods, often weeks, to achieve significant degradation, making it inefficient for practical applications. Additionally, techniques like ultrasound have been applied to recover polyethylene MPs from activated sludge, which reduces the risk of soil contamination. However, this ultrasound method has been associated with adverse impacts on the bacterial communities essential to healthy soil ecology. Therefore, while a few methods have aimed to degrade MPs, they have encountered critical challenges that limit their real-world applicability, particularly the time required and potential environmental side effects. This underscores the necessity of developing a degradation technique that is not only effective but also efficient and environmentally safe.
In recent years, electrooxidation (EO) has emerged as a promising approach for addressing complex pollutants in water, including pharmaceuticals, pesticides, and organic compounds resistant to conventional treatments. By utilizing an external electric current, EO induces oxidative reactions that break down contaminants without the need for extensive chemical additives. Although EO has proven effective in treating various organic pollutants, its application in MP degradation remains relatively unexplored. This gap is partly due to challenges associated with optimizing EO systems specifically for MPs. The process has demonstrated environmental benefits, such as minimal toxic by-products and waste, making it a sustainable alternative for industrial use. However, EO's full potential in MP degradation is limited by a set of specific technical issues, mainly around electrode material optimization and mass transfer intensification, which are crucial for improving reaction rates and degradation efficiency in an aqueous environment.
One key challenge in the EO process is the tendency for gas bubbles to accumulate on the anode, creating a bubble curtain that hinders effective oxidation. This bubble formation, particularly on the BDD anodes often used in EO systems, leads to fouling that disrupts the anode's reactivity and slows the overall reaction rate. Addressing this fouling issue is crucial to maintaining efficiency, as anode fouling interferes with the continuity of electrochemical reactions, necessitating regular maintenance and reducing operational efficacy. Some studies have examined alternative reactor configurations or combined EO with ultrasound to increase mass transfer by removing these obstructive gas layers, but these setups can be complex, costly, or difficult to scale for regular use. While approaches such as rotating multielectrode reactors have shown promise in enhancing mass transfer for certain pollutants, including phenol, their efficacy and practicality in degrading MPs remain inconclusive.
Boron-doped diamond (BDD) electrodes have gained recognition for their robustness and efficiency in EO, especially with organic pollutants. Commercially available due to relatively accessible production processes, BDD electrodes offer durability and high oxidation potential, which are essential for tackling persistent pollutants like MPs. Yet, despite these advantages, BDD-based EO has faced limitations in MP applications due to fouling, slow reaction rates, and suboptimal mass transfer mechanisms. Some experimental work has attempted to modify reactor designs to enhance interaction between BDD anodes and MPs, aiming to increase degradation rates by creating favorable reaction environments. For example, a study using a lab-scale BDD EO setup suggested that polystyrene MPs could be oxidized indirectly by radicals formed in the reaction, yet this process still suffered from reaction inefficiencies. Additional research has also introduced innovations, such as modified Ti-based anodes and additives like sodium dodecyl sulfate (SDS), to boost EO efficacy for MP degradation, although such modifications raise concerns regarding environmental impact and chemical stability.
Thus, the field has identified a clear need for optimized EO reactors that address both fouling issues and mass transfer limitations in a way that allows for sustainable, high-efficiency MP degradation. Existing technologies have shown some results but require further development to achieve practical, high-throughput solutions for environmental MP degradation. While some advanced EO reactors and modified electrode materials have been developed to improve treatment effectiveness, they do not fully address the needs of a scalable, efficient EO system for MPs. This ongoing gap highlights the necessity for a targeted electrochemical reactor solution that can integrate optimized materials and innovative design features to reliably enhance MP degradation without significant operational drawbacks.
Summary of the Invention
This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features or essential features of the claimed subject matter. Nor is this summary intended to be used to limit the claimed subject matter's scope.

Both the foregoing summary and the following detailed description provide examples and are explanatory only. Accordingly, the foregoing summary and the following detailed description should not be considered to be restrictive. Further, features or variations may be provided in addition to those set forth herein. For example, embodiments may be directed to various feature combinations and sub-combinations described in the detailed description.
It is one of the objectives of the present invention to provide a rotating electrochemical reactor which is capable of degrading the microplastics (MPs) from wastewater in an efficient and environmentally friendly manner.
It is one of the objectives of the present invention to provide a rotating electrochemical reactor capable of degrading the polystyrene-microplastics (MPs) into nontoxic molecules like water and carbon dioxide without addition of chemicals.
It is one of the objectives of the present invention to provide a rotating electrochemical reactor capable of producing high centrifugal force enhancing the mass transfer and reaction area over the electrode surface.
It is one of the objectives of the present invention to provide a rotating electrochemical reactor having almost 100% current efficiency achieved by using the Boron-Doped Diamond (BDD) electrode.
It is one of the objectives of the present invention to provide a rotating electrochemical reactor for wastewater treatment to promote faster electro-oxidation processes which lowers the current efficiency and increases energy efficiency.
It is one of the objectives of the present invention to provide a rotating electrochemical reactor that avoids incineration of plastic waste which releases toxic chemicals, MPs, and NPs into the air and to evade the contamination of soil and water during landfilling.
It is one of the objectives of the present invention to provide a rotating electrochemical reactor that assist to diminish many negative aspects of the marine or aquatic fish, marine food chain and consequently curtail the threat to animals/humans due to consumption of MPs in different way.
It is one of the objectives of the present invention to provide a rotating electrochemical reactor having ease of operation, strong oxidation performance, and environmental compatibility, electrochemical oxidation process using RECR can be accepted as a promising technology for treating refractory organic wastewaters.
As a preliminary matter, it will readily be understood by one having ordinary skill in the relevant art that the present disclosure has broad utility and application. As should be understood, any embodiment may incorporate only one or a plurality of the above-disclosed aspects of the disclosure and may further incorporate only one or a plurality of the above-disclosed features. Furthermore, any embodiment discussed and identified as being "preferred" is considered to be part of a best mode contemplated for carrying out the embodiments of the present disclosure. Other embodiments also may be discussed for additional illustrative purposes in providing a full and enabling disclosure. Moreover, many embodiments, such as adaptations, variations, modifications, and equivalent arrangements, will be implicitly disclosed by the embodiments described herein and fall within the scope of the present disclosure.
Accordingly, while embodiments are described herein in detail in relation to one or more embodiments, it is to be understood that this disclosure is illustrative and exemplary of the present disclosure and are made merely for the purposes of providing a full and enabling disclosure. The detailed disclosure herein of one or more embodiments is not intended, nor is to be construed, to limit the scope of patent protection afforded in any claim of a patent issuing here from, which scope is to be defined by the claims and the equivalents thereof. It is not intended that the scope of patent protection be defined by reading into any claim a limitation found herein that does not explicitly appear in the claim itself.
Additionally, it is important to note that each term used herein refers to that which an ordinary artisan would understand such term to mean based on the contextual use of such term herein. To the extent that the meaning of a term used herein-as understood by the ordinary artisan based on the contextual use of such term-differs in any way from any particular dictionary definition of such term, it is intended that the meaning of the term as understood by the ordinary artisan should prevail.
Furthermore, it is important to note that, as used herein, "a" and "an" each generally denotes "at least one," but does not exclude a plurality unless the contextual use dictates otherwise. When used herein to join a list of items, "or" , "/" denotes "at least one of the items," but does not exclude a plurality of items of the list. Finally, when used herein to join a list of items, "and" denotes "all of the items of the list."
In accordance with one embodiment of the present invention, there is provided a rotating electrochemical reactor (RECR) for degrading polystyrene microplastics (PS-MPs) from water, the reactor comprising a jacketed glass vessel defining an inner volume for electrolyte and microplastic suspension containment, a rotating shaft coated with Teflon and operatively connected to a motor for imparting centrifugal motion, a plurality of electrode pairs including a boron-doped diamond (BDD) anode and a titanium cathode, the electrodes positioned with a uniform spacing of approximately 1 cm, teflon-coated holders/supporters mounting said electrodes to the shaft with an arrangement minimizing inter-electrode spacing to facilitate intensified mass transfer, and a DC power supply providing electrical current across the electrodes to initiate an electro-oxidation process for PS-MPs degradation.
In accordance with one embodiment of the present invention, there is provided a rotating electrochemical reactor (RECR) for degrading polystyrene microplastics (PS-MPs) from water, the reactor comprising a jacketed glass vessel defining an inner volume for electrolyte and microplastic suspension containment, a rotating shaft coated with Teflon and operatively connected to a motor for imparting centrifugal motion, a plurality of electrode pairs including a boron-doped diamond (BDD) anode and a titanium cathode, the electrodes positioned with a uniform spacing of approximately 1 cm, teflon-coated holders/supporters mounting said electrodes to the shaft with an arrangement minimizing inter-electrode spacing to facilitate intensified mass transfer, and a DC power supply providing electrical current across the electrodes to initiate an electro-oxidation process for PS-MPs degradation, wherein the rotational speed of the shaft is adjustable, establishing centrifugal force that regenerates the electrochemical reaction area by reducing bubble formation on the electrode surfaces, thereby enhancing mass transfer efficiency and minimizing ohmic resistance.
In accordance with one embodiment of the present invention, there is provided a rotating electrochemical reactor (RECR) for degrading polystyrene microplastics (PS-MPs) from water, the reactor comprising a jacketed glass vessel defining an inner volume for electrolyte and microplastic suspension containment, a rotating shaft coated with Teflon and operatively connected to a motor for imparting centrifugal motion, a plurality of electrode pairs including a boron-doped diamond (BDD) anode and a titanium cathode, the electrodes positioned with a uniform spacing of approximately 1 cm, teflon-coated holders/supporters mounting said electrodes to the shaft with an arrangement minimizing inter-electrode spacing to facilitate intensified mass transfer, and a DC power supply providing electrical current across the electrodes to initiate an electro-oxidation process for PS-MPs degradation, wherein said reactor further comprising a pH sensor and a temperature sensor for maintaining operational parameters, with the pH range controlled between 6.0 and 7.0 and monitored throughout electro-oxidation, ensuring optimal degradation efficiency.
In accordance with one embodiment of the present invention, there is provided a rotating electrochemical reactor (RECR) for degrading polystyrene microplastics (PS-MPs) from water, the reactor comprising a jacketed glass vessel defining an inner volume for electrolyte and microplastic suspension containment, a rotating shaft coated with Teflon and operatively connected to a motor for imparting centrifugal motion, a plurality of electrode pairs including a boron-doped diamond (BDD) anode and a titanium cathode, the electrodes positioned with a uniform spacing of approximately 1 cm, teflon-coated holders/supporters mounting said electrodes to the shaft with an arrangement minimizing inter-electrode spacing to facilitate intensified mass transfer, and a DC power supply providing electrical current across the electrodes to initiate an electro-oxidation process for PS-MPs degradation, wherein the reactor further comprising inlet and outlet lines for continuous feed and evacuation of the water-electrolyte solution, and an outlet line for gas discharge allowing for safe venting of gases produced during electro-oxidation.
In accordance with one embodiment of the present invention, there is provided a rotating electrochemical reactor (RECR) for degrading polystyrene microplastics (PS-MPs) from water, the reactor comprising a jacketed glass vessel defining an inner volume for electrolyte and microplastic suspension containment, a rotating shaft coated with Teflon and operatively connected to a motor for imparting centrifugal motion, a plurality of electrode pairs including a boron-doped diamond (BDD) anode and a titanium cathode, the electrodes positioned with a uniform spacing of approximately 1 cm, teflon-coated holders/supporters mounting said electrodes to the shaft with an arrangement minimizing inter-electrode spacing to facilitate intensified mass transfer, and a DC power supply providing electrical current across the electrodes to initiate an electro-oxidation process for PS-MPs degradation, wherein the support structure for the rotating shaft and electrodes is coated with Teflon, thereby minimizing the risk of unwanted side reactions between the electrolyte and non-electrode components.
In accordance with one embodiment of the present invention, there is provided a rotating electrochemical reactor (RECR) for degrading polystyrene microplastics (PS-MPs) from water, the reactor comprising a jacketed glass vessel defining an inner volume for electrolyte and microplastic suspension containment, a rotating shaft coated with Teflon and operatively connected to a motor for imparting centrifugal motion, a plurality of electrode pairs including a boron-doped diamond (BDD) anode and a titanium cathode, the electrodes positioned with a uniform spacing of approximately 1 cm, teflon-coated holders/supporters mounting said electrodes to the shaft with an arrangement minimizing inter-electrode spacing to facilitate intensified mass transfer, and a DC power supply providing electrical current across the electrodes to initiate an electro-oxidation process for PS-MPs degradation, wherein the electrochemical process utilizes Na₂SO₄ as an electrolyte in a concentration of approximately 0.03 M, optimizing conductivity while minimizing chemical additives, thus promoting environmentally compatible operation.
In accordance with one embodiment of the present invention, there is provided a method for degrading polystyrene microplastics (PS-MPs) in water using the rotating electrochemical reactor (RECR), wherein the method comprising preparing a mono-dispersed suspension of PS-MPs in water within a stainless steel stirring vessel, introducing Na₂SO₄ electrolyte and monitoring the pH and temperature of the suspension, transferring the suspension to the RECR via a peristaltic pump, and applying electrical current and initiating shaft rotation to produce electrochemical oxidation on the BDD anode surface, thereby generating oxidizing radicals to break down PS-MPs.
In accordance with one embodiment of the present invention, there is provided a method for degrading polystyrene microplastics (PS-MPs) in water using the rotating electrochemical reactor (RECR), wherein the method comprising preparing a mono-dispersed suspension of PS-MPs in water within a stainless steel stirring vessel, introducing Na₂SO₄ electrolyte and monitoring the pH and temperature of the suspension, transferring the suspension to the RECR via a peristaltic pump, and applying electrical current and initiating shaft rotation to produce electrochemical oxidation on the BDD anode surface, thereby generating oxidizing radicals to break down PS-MPs, wherein the produced gases, including CO, CO₂, and H₂, are monitored using a gas chromatograph (GC) to evaluate PS-MPs degradation efficiency and ensure conversion to non-toxic byproducts.
In accordance with one embodiment of the present invention, there is provided a method for degrading polystyrene microplastics (PS-MPs) in water using the rotating electrochemical reactor (RECR), wherein the method comprising preparing a mono-dispersed suspension of PS-MPs in water within a stainless steel stirring vessel, introducing Na₂SO₄ electrolyte and monitoring the pH and temperature of the suspension, transferring the suspension to the RECR via a peristaltic pump, and applying electrical current and initiating shaft rotation to produce electrochemical oxidation on the BDD anode surface, thereby generating oxidizing radicals to break down PS-MPs, wherein Total Organic Carbon (TOC) analysis is performed at specified intervals to determine degradation progress and efficacy of PS-MPs mineralization.
Brief Description of the Drawings
Figure 1 shows the setup of Rotating Electro-Chemical Reactor.
Figure 2 shows the three-dimensional representation of Rotating Electro-Chemical Reactor as explained in one of the embodiments of the present invention.
Figure 3 shows detachable electrodes (BDD and Ti) with Teflon supporter mounted on the vertical Teflon coated rotating shaft by the motor.

Detailed Description of the Invention
The following detailed description refers to the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the following description to refer to the same or similar elements. While many embodiments of the disclosure may be described, modifications, adaptations, and other implementations are possible. For example, substitutions, additions, or modifications may be made to the elements illustrated in the drawings, and the methods described herein may be modified by substituting, reordering, or adding stages to the disclosed methods. Accordingly, the following detailed description does not limit the disclosure. Instead, the proper scope of the disclosure is defined by the appended claims. The present disclosure contains headers. It should be understood that these headers are used as references and are not to be construed as limiting upon the subjected matter disclosed under the header.
In the present invention, the rotating electrochemical reactor aims to degrade the polystyrene micro plastics (PS-MPs) from water in a very efficient way by reducing all the drawbacks of conventional electrochemical method. The rotating electrodes (boron doped diamond, BDD as an anode and titanium as a cathode) help to completely decrease the ohmic resistance of the electrolyte by removing the formation of bubble curtain as a side reaction over the electrode surface and the electro-oxidation reaction area are regenerated, resulting in enlarging the effective area of mass transfer toward the surface of electrode. This RECR promotes faster electro-oxidation processes which lowers the current efficiency and increases energy consumption. The transport method between the reactant and active radicals is intensified by this centrifugal motion of electrodes. Internal design of the rotor and electrodes played a major role in prompting the execution of this degradation procedure. By the application of the device RECR in the wastewater effluent treatment plant, it can assist to decline many negative aspects of the marine or aquatic fish, marine food chain and consequently curtail the threat to animals due to consumption of MPs in different way.
In accordance with one preferred embodiment, "Rotating Electro-Chemical Reactor" (RECR) is intended to focus on the degradation mechanism of polystyrene microplastics (PS-MPs) in water in a faster and environment friendly way without producing any toxic byproduct. In this reactor, electro-oxidation reaction takes place on the anode surface by direct and indirect electrochemical process based on in-situ generation of oxidizing radicals like hydroxyls (•OH) which allows it to break the polymeric bonds of PS-MPs and degrade them. Simultaneously, due to the side reaction of this electro-oxidation process there is a formation of gas bubbles on the electrode surface which hampered the mass transfer and electrochemical reaction. The RECR is capable of removing the formation of bubble curtain over the surface of electrode by incorporating the multiple rotating electrodes inside the reactor. For the centrifugal motion of electrodes, the electrochemical oxidation reaction area will be regenerated, thickness of the concentration boundary layer is minimized which results in enlarging the effective area of mass transfer toward the surface of electrode. The transport process between the reactant and active radicals is also intensified by the forced convection flow assisted by centrifugal motion. The rectangular type of boron doped diamond (BDD) electrodes and titanium electrodes are used as rotating anode and rotating cathode respectively in the RECR. The four pairs of anodes and cathodes are placed with 1 cm spacing in between two Teflon coated supporters and attached on the shaft driven by a motor. The rotating arrangement (including shaft) excluding electrodes are covered with Teflon coating and placed inside a jacketed glass vessel of 1.25-liter inner volume.
Referring to Figure 1-3, The "Rotating Electro-Chemical Reactor" RECR comprises of several parts wherein, 1 - Jacketed glass vessel, 2 - Rotating shaft (Teflon coated), 3 - Holder / Supporter (Teflon coated) for electrodes, 4 - Boron Doped Dimond (BDD) anode, 5 - Titanium cathode, 6 - Negative (-) terminal, 7 - Positive (+) terminal, 8 - Outlet line for produced gas, 9 - Motor, 10 - Inlet line for feed solution, 11 - Outlet line for feed solution, 12 - Inlet water line in jacketed part, 13 - Outlet water line from jacketed part, 14 - Valve, 15 - SAE 316L stainless steel stirring vessel, 16 - pH sensor, 17 - Temperature sensor, 18 - SAE 316L stainless steel stirrer, 19 - Peristaltic pump, 20 - Inlet port for raw materials (water, PS-MPs, electrolyte), 21 - Controller box (for pH, temperature and RPM), 22 - Total Organic Carbon (TOC) analyzer, 23 - DC Power supply (30 V, 10 A), 24 - Gas chromatography (GC), 25 - Pipeline.
Fig. 1 illustrates the "Rotating Electro-Chemical Reactor" RECR setup, which is majorly segmented into two sections, namely RECR (Fig. 2) and stirring vessel (15). Before starting the experiments, the mono-dispersed suspension of PS-MPs with known concentration in deionized water are prepared spontaneously in a 2-liter volume of SAE 316L stainless steel stirring vessel (15) for 30 min at 200 rpm stirring speed. The varying amount of Na2SO4 electrolyte is added through inlet port (20) with the suspension for the improvement of chemical conductivity. The prepared solution pH and temperature are checked by pH sensor (16) and temperature sensor (17). The pH range is maintained between 6.0 to 7.0. All the experiments are carried out at ambient temperature. After making the proper dispersion of PS-MPs (known concentration) in the stirring vessel (15), the solution is fed inside the RECR through inlet line (10) by peristaltic pump (19) to evaluate the performance of the reactor in batch and continuous mode. The reaction takes place by turning on the electric current and rotor with the help of DC power supply (23). The operating solution volume in the RECR (Fig. 2) is 1 L. The water flows through jacketed part of the glass vessel (1) or RECR from point (12) to (13) for minimizing the solution evaporation due to the temperature increase induced by electro-oxidation at high current intensities. The solution is recirculated from RECR to stirring vessel (15) after 30 min of the reaction in the RECR. The Total Organic Carbon (TOC) values are measured by TOC analyzer (22) at different time intervals to find the efficacy of the degradation process. Due to the electrochemical degradation of PS-MPs, the produced gases (CO, CO2 and H2) are analyzed by Gas Chromatography (GC) (24) at different time intervals to check the conversion of PS-MPs into CO2 and H2O.
Fig. 2 shows the three-dimensional representation of "Rotating Electro-Chemical Reactor" RECR which is mainly segmented into two sections namely rotating arrangements (Fig. 3) and jacketed glass vessel (1) with 1.25 L volume. The rotating arrangements (Fig. 3) are supported by a Teflon coated shaft (2). The shaft (2) can manually be mounted or detached to the motor (9).
The rotating arrangement is described in Fig. 3 which shows the different view of the detachable 4 pair of electrodes i.e. BDD anode (4) and Ti cathode (5) in between two Teflon supporter or holder (3). This supporter or holder (3) is mounted on the vertical Teflon coated shaft (2). The electrodes are rectangular in shape with a length of 5.04 cm, a breadth of 2.04 cm, a thickness of 0.296 cm, and a surface area of 24.75 cm2. The Teflon coated supporters or holder (3) has four wings. All wings consist of 1 pair of electrodes i.e. one BDD anode (4) and one Ti cathode (5) with 1 cm spacing. Each BDD anode (4) and Ti cathode (5) are linked with the positive terminal (7) and negative terminal (6) outputs of a DC power supply (23), respectively. The rotation of the shaft (2) with four pairs of electrodes can also be controlled by the DC power supply (23).

Further, the internal design of the rotor and electrodes of RECR plays a major role in prompting the execution of the PS-MPs degradation procedure. In RECR, rotating electrode completely decreases the ohmic resistance of the electrolyte by reducing the bubble formation over the electrode surface resulting in an increase of effective surface area of mass transfer and electrochemical reaction. There is a highest removal efficiency (more than 95%) is achieved within 1 hr at 200 rpm using lower current 2 A and lower electrolyte (Na2SO4) concentration (0.03 M) for this electrochemical oxidation process in RECR which enhances the intensification of the electrochemical process. The research of the present invention on rotating electrodes can degrade the PS-MPs in a very faster way using less chemicals (very low concentration (0.03 M) of Na2SO4 as an electrolyte). The presence of Teflon coating over the rotating part (excluding the electrodes) helps to minimize the side reaction with the other material. The reactor RECR enhances the degradation rate with minimum time scale by enhancing the mass transfer and electrochemical reaction and reducing the anode fouling due to centrifugal force of the rotating electrode. In RECR, rotating electrode completely decreases the ohmic resistance of the electrolyte by reducing the bubble formation over the electrode surface resulting in increase of effective surface area of mass transfer and electrochemical reaction.
The present invention has application in water and wastewater treatment plant (WWTP) in packaging, textiles, polymer and other processing industry.
While the invention is amenable to various modifications and alternative forms, some embodiments have been illustrated by way of example in the drawings and are described in detail above. The intention, however, is not to limit the invention by those examples and the invention is intended to cover all modifications, equivalents, and alternatives to the embodiments described in this specification.

The embodiments in the specification are described in a progressive manner and the focus of description in each embodiment is the difference from other embodiments. For same or similar parts of each embodiment, reference may be made to each other.

It will be appreciated by those skilled in the art that the above description was in respect of preferred embodiments and that various alterations and modifications are possible within the broad scope of the appended claims without departing from the spirit of the invention with the necessary modifications. , Claims:We Claim:
1. A rotating electrochemical reactor (RECR) for degrading polystyrene microplastics (PS-MPs) from water, the reactor comprising:
a jacketed glass vessel defining an inner volume for electrolyte and microplastic suspension containment;
a rotating shaft coated with Teflon and operatively connected to a motor for imparting centrifugal motion;
a plurality of electrode pairs including a boron-doped diamond (BDD) anode and a titanium cathode, the electrodes positioned with a uniform spacing of approximately 1 cm;
teflon-coated holders/supporters mounting said electrodes to the shaft with an arrangement minimizing inter-electrode spacing to facilitate intensified mass transfer; and
a DC power supply providing electrical current across the electrodes to initiate an electro-oxidation process for PS-MPs degradation.
2. The rotating electrochemical reactor (RECR) as claimed in claim 1, wherein the rotational speed of the shaft is adjustable, establishing centrifugal force that regenerates the electrochemical reaction area by reducing bubble formation on the electrode surfaces, thereby enhancing mass transfer efficiency and minimizing ohmic resistance.
3. The rotating electrochemical reactor (RECR) as claimed in claim 1, further comprising a pH sensor and a temperature sensor for maintaining operational parameters, with the pH range controlled between 6.0 and 7.0 and monitored throughout electro-oxidation, ensuring optimal degradation efficiency.
4. The rotating electrochemical reactor (RECR) as claimed in claim 1, further comprising:
inlet and outlet lines for continuous feed and evacuation of the water-electrolyte solution, and
an outlet line for gas discharge allowing for safe venting of gases produced during electro-oxidation.
5. The rotating electrochemical reactor (RECR) as claimed in claim 1, wherein the support structure for the rotating shaft and electrodes is coated with Teflon, thereby minimizing the risk of unwanted side reactions between the electrolyte and non-electrode components.
6. The rotating electrochemical reactor (RECR) as claimed in claim 1, wherein the electrochemical process utilizes Na₂SO₄ as an electrolyte in a concentration of approximately 0.03 M, optimizing conductivity while minimizing chemical additives, thus promoting environmentally compatible operation.
7. A method for degrading polystyrene microplastics (PS-MPs) in water using the rotating electrochemical reactor (RECR) of claim 1, the method comprising:
preparing a mono-dispersed suspension of PS-MPs in water within a stainless steel stirring vessel;
introducing Na₂SO₄ electrolyte and monitoring the pH and temperature of the suspension;
transferring the suspension to the RECR via a peristaltic pump; and
applying electrical current and initiating shaft rotation to produce electrochemical oxidation on the BDD anode surface, thereby generating oxidizing radicals to break down PS-MPs.
8. The method as claimed in claim 7, wherein the produced gases, including CO, CO₂, and H₂, are monitored using a gas chromatograph (GC) to evaluate PS-MPs degradation efficiency and ensure conversion to non-toxic byproducts.
9. The method as claimed in claim 7, wherein Total Organic Carbon (TOC) analysis is performed at specified intervals to determine degradation progress and efficacy of PS-MPs mineralization.

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