2024 年 65 巻 10 号 p. 1301-1309
A photocatalyst based on Ti3C2/ZnCo2O4/ZnIn2S4 composite material is prepared for the detection and treatment of persistent organic pollutants in groundwater environment of subway stations. And it is characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy. Then, a monitoring and governance system for persistent organic pollutants in the water environment is established, including sensor networks, data collection and processing, pollutant monitoring, and governance control. Finally, the degradation efficiency of the photocatalytic coupled ozone flow reactor for three types of chlorophenol organic compounds is experimentally verified to reach 93%, 86%, and 83%, respectively. The monitoring and treatment system for persistent organic pollutants in the water environment has achieved a removal rate of 90% for chemical oxygen demand (COD) and 80% for suspended solids. This study shows that the photocatalytic coupled ozone flow reactor has a high degradation effect on chlorophenol organic compounds. The monitoring and treatment system for persistent organic pollutants in the water environment has significantly reduced the concentration of heavy metal ions and achieved good removal effects on COD and suspended solids. This study provides effective technologies and methods for the monitoring and management of persistent organic pollutants in the water environment, which helps to solve water pollution problems, improve water environment quality, and protect water resources and ecological environment.
This study successfully prepared a new type of photocatalyst Ti3C2/ZnCo2O4/ZnIn2S4 and applied it to FCOFR. At the same time, this study designed a water environment POPs monitoring and treatment system based on IoT technology, which significantly improved the concentration of chlorophenol organic compounds and heavy metal ions. The results showed that the degradation efficiency of PCOFR for three types of chlorophenol organic compounds was 93%, 86%, and 83%, respectively, and the hydrogen production rate was 27369 µmol/h/g, 24087 µmol/h/g and 18694 µmol/h/g. In addition, the system significantly reduces the concentration of heavy metal ions, with removal rates of 90% and 80% for COD and suspended solids, respectively.
Persistent organic pollutants (POPs) are a class of organic compounds with high environmental stability and bioaccumulation, mainly including pesticides, industrial organic solvents, polychlorinated biphenyls, etc. [1]. These pollutants are difficult to degrade in the aquatic environment and accumulate through the food chain, posing a potential threat to ecosystems and human health [2]. Therefore, it is of great significance to study the monitoring and control technologies of POPs in the groundwater environment of subway stations (GEoSS). At present, the commonly used monitoring methods for POPs in GEoSS include chemical analysis, biological monitoring, and remote sensing technology [3]. However, these methods still have certain limitations in practical applications, such as long analysis time, high cost, and low accuracy [4]. Therefore, developing more efficient and economical monitoring methods is an important task for current research. The commonly used POPs treatment technologies in GEoSS include bioremediation, chemical oxidation, and adsorption [5]. These technologies have certain effects in practical applications. But there are also many limitations, such as limited bioremediation by microbial species and environmental conditions, potential secondary pollution caused by chemical oxidation, and issues with adsorbent regeneration and treatment [6]. Therefore, it is necessary to seek new and widely applied pollutant treatment technologies. Nano photocatalytic materials (NApm) have the advantages of efficient photocatalytic activity, good biocompatibility, and long service life, which can effectively degrade POPs in aquatic environments [7]. Especially under light conditions, NApm can exert the redox effects of photo generated electrons and holes, promoting the oxidation reaction of organic pollutants and achieving the degradation of pollutants [8]. In addition, NApm has a smaller particle size and larger specific surface area, making it easy to come into contact with pollutants in water, thereby improving the degradation efficiency of pollutants [9]. It can be seen that NApm has significant advantages and potential in the treatment of POPs in GEoSS. Therefore, this study focuses on the monitoring and treatment of POPs in GEoSS, explores the preparation and performance of NApm, and constructs a water quality monitoring and treatment system, hoping to provide scientific basis for achieving sustainable development of water environment.
Chlorophenols have high stability and difficulty in degradation, and can exist for a long time in water bodies [10]. Photocatalytic degradation has the advantages of high efficiency, no secondary pollution, and easy operation, and is widely used in fields such as water treatment and air purification [11]. Therefore, this study prepared a new composite photocatalyst (Ti3C2/ZnCo2O4/ZnIn2S4) based on Ti3C2, and the preparation process is shown in Fig. 1.
The preparation process of Ti3C2/ZnCo2O4/ZnIn2S4.
Preparation of Ti3C2 nanosheets: Firstly, Ti3AlC2 material was added to HF solution, and Ti3C2 nanosheets were obtained by stirring and continuous treatment at 40°C for 24 hours. Then, centrifuge and wash with deionized water to achieve a pH value greater than 6. Next, dry under vacuum conditions at 60°C to obtain multilayer Ti3C2. The multi-layer Ti3C2 was treated overnight with DMSO and further peeled off using ultrasound at a frequency of 500 Hz for a duration of 1 hour. Collect the stripped Ti3C2 and wash with ethanol and deionized water to remove residual DMSO. Finally, ultrasound treatment was performed under N2 atmosphere for 6 hours, and the precipitate was dispersed and dissolved in deionized water. After centrifugation and vacuum drying, a single-layer Ti3C2 nanosheet was obtained.
Preparation of ZnCo2O4 nanoparticles: Dissolve 0.1 mmol of Zn(NO3)2·6H2O and 0.1 mmol of Co(NO3)2·6H2O in 30 mL of methanol and stir continuously. Next, dissolve 328 mg of 2-methylimidazole into 10 mL of methanol solution, and then mix the two solutions. After standing at room temperature for 24 hours, the product was centrifuged, washed three times with methanol, and then vacuum dried at 60°C to obtain ZnCo ZIF. Finally, ZnCo ZIF was calcined in an O2 atmosphere and heated at a rate of 2°C/min to 300°C for 3 hours to obtain the bimetallic oxide ZnCo2O4 dodecahedron.
Preparation of ZnIn2S4 nanoparticles: Dissolve 0.29 mmol ZnCl2, 0.29 mmol InCl3·4H2O, and 0.71 mmol TAA in ultrapure water, stir for 60 minutes, and keep in an oil bath at 80°C for 2 hours. Then cool to room temperature, collect the precipitate and wash several times with ethanol and distilled water, and finally dry in a 60°C oven.
Preparation of Ti3C2/ZnCo2O4/ZnIn2S4 composites: Immerse Ti3C2 in ultrapure water and sonicate for 15 minutes to form a uniform suspension of Ti3C2. Then add ZnCo2O4/ZnIn2S4 powder to the suspension and stir for 2 hours. Synthesize Ti3C2/ZnCo2O4/ZnIn2S4 composite materials with different Ti3C2 mass ratios of 0.5, 2, and 5.
After the photocatalytic production is completed, corresponding reactors need to be prepared. This study uses a glass reactor and a visible light source based on the characteristics of Ti3C2/ZnCo2O4/ZnIn2S4. The reactor consists of an inlet (including the distribution of pollutants and actual water), an air inlet (a mixture of ozone and oxygen), a microporous aeration head (which fully disperses the gas entering the reaction chamber into small bubbles), a titanium dioxide double helix photocatalytic carrier (including photocatalyst and its stirring function), a glass tube (isolating UV lamp from solid-liquid), an outlet (for sampling), and a gas outlet (for collecting residual gas generated during the reaction process). The reactor adopts ozone resistant polytetrafluoroethylene material as the overall material, and considers the participation of ultraviolet lamps throughout the reaction process, so the reactor also has the characteristics of sealing and shading. The light source uses a purple light lamp with a wavelength of 410 nm and a specification of 120 mm UVB, which is used to provide energy to excite the luminescent catalyst. During the experiment, a UV lamp was installed inside the glass tube of the reactor to illuminate the catalytic carrier. The experiment uses chemical bonding to react the photocatalyst with the inner wall surface of the reactor, forming covalent bonds to fix the photocatalyst. Firstly, prepare a clean inner wall of the reactor and evenly apply 0.1 mmol of silane and photocatalyst powder onto the inner wall of the reactor, allowing the reagent to fully contact the photocatalyst and inner wall surface. Dry at room temperature of 25°C to allow the chemical bonding reaction to fully proceed. At the same time, an ozone generator is installed to generate ozone gas, usually consisting of an ozone generator and an ozone concentration control device. Establish a gas circulation system, including inlet and outlet pipelines, and circulation pipelines, for introducing reactants and ozone gases, discharging reaction products and unreacted gases, and circulating reactants and ozone gases. Install a temperature control system, including heating devices and temperature sensors, to control the temperature of the reactor. Heating devices usually use resistors, with a power selection between 800 W. The temperature sensor adopts Texas Instruments thermistor, with a measurement range of −50°C to 150°C and an accuracy of ±0.1°C. At the same time, a reaction monitoring system is installed to monitor the process of the reaction and the generation of products. Common monitoring methods include UV visible spectroscopy, mass spectrometry, gas chromatography, etc. The wavelength of UV visible spectroscopy is 190–1100 nm, the absorbance is 70%, and the transmittance is 30%. It is measured every hour. The measurement parameters of mass spectrometry include retention time, peak area, and peak height, which are measured every half hour. Measurement frequency: the measurement parameters of gas chromatography include chromatographic peak, retention time, and peak area, measured every hour. Finally, safety facilities such as explosion-proof devices, exhaust devices, and emergency shutdown devices should be installed around the reactor to ensure the safe operation of the reaction. The photocatalytic degradation experiment was conducted in a 1 L polytetrafluoro reactor, using Ti3C2/ZnCo2O4/ZnIn2S4 as the photocatalyst and ozone and ultraviolet lamp as oxidants. The concentration of photocatalyst is 0.1 mol/L, and the total dosage is 0.1 mol. The UVB lamp has a power of 9 W, the model is PHILIPS 9 W, the reaction time is 12 hours, and the solution pH is neutral to slightly alkaline. To determine the degree of pollutant degradation, the ozone concentration in the exhaust gas is detected, and the water sample filtered through a 0.22 µm filter membrane is tested. Figure 2 is the structural diagram of a PCOFR.
Structure of PCOFR.
Experimental instruments: Magnetic stirrer 78-1 (Jintan Scientific Instrument Co., Ltd.), ultrasonic cleaner KQ100-E (Kunshan Ultrasonic Instrument Co., Ltd.), electric constant temperature drying oven 601-1 (Dalian Fourth Instrument Factory), analytical balance FA2104N (Shanghai Precision Scientific Instrument Co., Ltd.), scanning electron microscope Gemini 300 (Zeiss, Germany), transmission electron microscope Hitachi H-800 (Hitachi, Japan), X-ray diffractometer D8 Focus (Bruker, Germany) X-ray photoelectron spectrometer Axis Supra (Shimadzu, Japan), UV spectrophotometer Lamda 900 (PerkinElmer, USA), fluorescence spectrophotometer, hydrogen generator, air generator, optical power meter, xenon lamp light source system, photocatalytic activity evaluation system FLU0R0MAX-4 (HORIBA, USA), gas chromatograph GC7920 (Beijing Zhongjiao Jinyuan Technology Co., Ltd.). WYJ series stabilized DC power supply (China Shanjie Electric Technology Co., Ltd.), pipette (Jinan Oulaibo Technology Co., Ltd.), and Autosorb-iQ-C type fully automatic physical/chemical adsorption instrument (Conta Instruments Co., Ltd. in the United States).
2.2 Design of water environment POPs monitoring and treatment systemWater environment POPs refer to organic compounds that are difficult to degrade, toxic, and bioaccumulative in water bodies, such as pesticides, industrial chemicals, and organic compounds generated by human activities. Monitoring and controlling POPs in the water environment is an important task for protecting water resources and the ecological environment. Therefore, this study proposes a water environment POPs monitoring and governance system based on Internet of Things (IoT) technology, as shown in Fig. 3.
The monitoring and treatment system for persistent organic pollutants in the water environment using Internet of Things technology.
Sensor network: Multiple sensor nodes are arranged in the water environment to monitor water quality parameters in real-time, such as dissolved oxygen, pH value, conductivity, temperature, etc. These sensor nodes can transmit data to base stations or cloud platforms through wireless communication technology. The layout of sensor nodes needs to consider the characteristics of the water environment and the distribution of pollution sources to ensure the comprehensiveness and accuracy of monitoring.
Data collection and processing: The data collected by sensor nodes is uploaded to the base station or cloud platform through communication modules. Base stations or cloud platforms store, process, and analyze data for real-time monitoring of pollution in the water environment. The process of data collection and processing needs to consider the real-time and accuracy of the data, as well as the security and privacy protection of the data.
POPs monitoring: Specific sensors can be added to the system to monitor the concentration of POPs, such as chlorophenol organic compounds. These sensors can be measured through methods such as chemical analysis or spectral analysis. The selection and arrangement of sensors need to consider the sensitivity and accuracy of monitoring, as well as the stability and durability of sensors.
Data analysis and early warning: Based on the collected data, the system can conduct data analysis and modeling to monitor the levels of organic pollutants in the water environment in real-time. When the concentration of organic pollutants exceeds the preset threshold, the system can send warning information to relevant personnel through SMS, email, or APP. The calculation of the preset threshold is eq. (1).
| \begin{equation} \textit{Threshold} = \textit{Ave} + \alpha \times \beta \end{equation} | (1) |
In eq. (1), the preset threshold for organic pollutants is Threshold. The average organic pollution concentration is Ave. The preset sensitivity coefficient is α. The standard deviation of the warning is β. The process of data analysis and early warning needs to consider the accuracy and real-time performance of algorithms, as well as the timeliness and effectiveness of early warning information.
Governance control: The system can be linked with governance equipment (such as integrated sewage treatment equipment (ISTE), sewage treatment plants, sewage outlets, etc.) to achieve governance control of pollutants. The ISTE used in this study is Fig. 4. The treatment system mainly consists of a hydrophobic organic solvent waste liquid treatment unit and a hydrophilic organic matter waste liquid treatment unit. The hydrophobic organic solvent wastewater treatment unit removes impurities through a bag filter and achieves the separation of solvent phase and wastewater phase through the principle of similar phase solubility. The hydrophobic solvent discharge system is entrusted to a third party for transportation and disposal, and the wastewater is discharged into the storage tank of hydrophilic organic waste liquid for subsequent treatment. The hydrophilic organic waste liquid treatment unit undergoes processes such as emulsion demulsification, heavy metal demulsification/desorption, and organic pollutant oxidation after removing impurities through a bag filter. The waste liquid undergoes chemical precipitation in a secondary reactor to remove pollutants such as heavy metals. The sludge is dehydrated through pressure filtration and outsourced for disposal. The filtrate is filtered through a bag filter and enters the resin adsorption unit to further remove trace heavy metals. Inorganic waste liquid and specialized waste liquid share a common treatment unit with hydrophilic organic waste liquid, and pollutants are removed through the same treatment steps. When the concentration of pollutants exceeds the threshold, the system can trigger corresponding treatment equipment, such as starting a photocatalytic reactor to degrade organic pollutants and carry out pollutant treatment and removal.
Integrated sewage treatment equipment.
The efficiency of photocatalytic degradation of organic pollutants is eq. (2).
| \begin{equation} \eta = \frac{\textit{Before}_{\textit{con}} - \textit{After}_{\textit{con}}}{\textit{Before}_{\textit{con}}} \times 100\% \end{equation} | (2) |
In eq. (2), the degradation efficiency is η. The pollutant concentrations before and after degradation are Beforecon and Aftercon, respectively. The process of governance control needs to consider the response speed and governance effectiveness of equipment, as well as the synergy and stability between the system and equipment.
Data visualization and remote monitoring: The system visualizes and displays the collected data through charts, maps, and other methods, making it convenient for users to monitor and analyze. At the same time, users can view the monitoring status of the water environment in real-time through the remote monitoring platform, and perform remote control and management. This process needs to consider the friendliness of the interface and the convenience of operation, as well as the stability and security of the system.
Overall, the design of a water environment POPs monitoring and governance system based on IoT technology can achieve real-time monitoring, data analysis, and early warning of POPs in the water environment. Moreover, it can be linked with governance equipment to improve the efficiency and accuracy of water environment governance. This system can provide scientific basis and technical support for water environment protection and governance, and promote sustainable development of the water environment.
Scanning electron microscopy (SEM) images have high resolution and magnification, and can display detailed information such as surface morphology, particle distribution, crystal structure, and fiber morphology of materials. The SEM images of Ti3C2/ZnCo2O4/ZnIn2S4 photocatalyst related materials are shown in Fig. 5. In Fig. 5(A), the multi-layer accordion shape of Ti3C2 after etching with Ti3AlC2. In Fig. 5(B), the surface of ZnCo2O4 after calcination is relatively rough, with clear boundary edges and corners, presenting a loosely packed state. In Fig. 5(C) and 5(D), a large number of cross-linked nanosheets form irregular clusters of ZnIn2S4 in their original state. During the synthesis process of ZnIn2S4, the interaction between nanosheets leads to their spontaneous aggregation to form irregular clusters. This self-assembly phenomenon can be controlled by adjusting the synthesis conditions and material properties, thereby achieving the regulation of the structure and properties of ZnIn2S4. The Ti3C2/ZnCo2O4/ZnIn2S4 photocatalyst has a flower like microsphere structure, and the morphology of Ti3C2 is quantum dots. The close combination of composite materials promotes the separation and migration of photo induced carriers in the photocatalytic hydrogen production process.
SEM images of Ti3C2/ZnCo2O4/ZnIn2S4 photocatalyst related materials ((A) SEM image of multilayer Ti3C2; (B) SEM image of ZnCo2O4; (C) SEM image of ZnIn2S4; (D) SEM image of Ti3C2/ZnCo2O4/ZnIn2S4).
Energy dispersive X-ray spectroscopy (EDS) surface scanning is a technique used to analyze material composition. It determines the elemental composition of the material by scanning an electron beam on the surface and measuring the X-ray energy spectrum reflected by the material surface. The EDS surface scanning image of Ti3C2/ZnCo2O4/ZnIn2S4 photocatalyst is shown in Fig. 6. The element mapping map and EDS test results indicate that Zn, In, S, C, O, Co, and Ti elements exist and are evenly distributed in the Ti3C2/ZnCo2O4/ZnIn2S4 composite material, indicating that the Ti3C2/ZnCo2O4/ZnIn2S4 composite material has been successfully synthesized [12].
EDS surface scanning image of Ti3C2/ZnCo2O4/ZnIn2S4 photocatalyst.
The UV visible diffuse reflectance spectra of photocatalytic related materials are shown in Fig. 7. Through UV-vis DRS spectroscopy research, it is found that Ti3C2/ZnCo2O4/ZnIn2S4 composite material has strong light absorption ability. The absorption edge of ZnIn2S4 is about 500 nm, while Ti3C2 and ZnCo2O4 can fully absorb visible light, thus enhancing the light absorption ability of the composite material. According to UV-vis DRS measurements, the energy gap Eg of ZnCo2O4 is 1.70 eV, and the energy gap Eg of ZnIn2S4 is 2.47 eV. In addition, M-S plot characterization revealed that ZnCo2O4 is a p-type semiconductor and ZnIn2S4 is an n-type semiconductor. The in-situ coupling of n-type ZnIn2S4 and p-type ZnCo2O4 forms an effective p-n junction interface. The presence of this interface accelerates the separation rate of electron hole pairs, while appropriate bandgap width and improved light absorption enhance the photocatalytic performance of the composite material. In summary, Ti3C2/ZnCo2O4/ZnIn2S4 composite material has excellent photocatalytic performance.
UV visible diffuse reflectance spectra of photocatalytic materials.
The evaluation of the catalytic hydrogen production effect of the catalyst is shown in Fig. 8. The photocatalytic hydrogen production performance of the sample is investigated under visible light irradiation using triethanolamine as a sacrificial agent. The original ZnIn2S4 exhibits relatively low photocatalytic hydrogen production activity, possibly due to the rapid recombination process of photo generated electron hole pairs. After adding co catalyst TC quantum dots, the photocatalytic hydrogen production performance of the material is improved. In the Ti3C2/ZnCo2O4/ZnIn2S4 composite material, when the Ti3C2 content is 2%, the H2 production rate reaches 27369 µmol/h/g, which is nearly 32 times higher than the original ZnIn2S4. The 2% Ti3C2/ZnCo2O4/ZnIn2S4 composite material exhibits a peak external quantum efficiency (EQE) of 9.66% at 420 nm and 0.08% at 550 nm. This indicates good photocatalytic activity within the wavelength range of 550 nm. The Ti3C2/ZnCo2O4/ZnIn2S4 composite material still maintains good photocatalytic hydrogen production performance after three photocatalytic cycles, indicating excellent photocatalytic stability, which is consistent with the expected results [13].
Evaluation of catalytic hydrogen production efficiency of catalysts ((A) shows the relationship between the photocatalytic hydrogen production of materials and time; (B) shows photoelectric conversion efficiency diagram of Ti3C2/ZnCo2O4/ZnIn2S4; (C) shows experimental diagram of photocatalytic hydrogen production cycle).
This study conducted experiments on a certain groundwater at subway stations with severe chlorophenol organic pollution. The morphology and structure of the groundwater were simulated in the laboratory, and sensor placement and system construction were carried out. The application effect of the water environment POPs monitoring and treatment system were verified. The experiment used a PCOFR to treat the main chlorophenol organic compounds in the groundwater. The degradation effect of chlorophenol organic compounds is Fig. 9. In Fig. 9(A), the PCOFR achieved degradation efficiency of 93%, 86%, and 83% for the three chlorophenol organic compounds of 2-Chlorophenol (2-CP), 2,4-Dichlorphenol (2,4-DCP), 2,4,6-Trichlorphenol (2,4,6-TCP), respectively. This reactor has a high degradation effect on all three types of chlorophenol organic compounds. However, in Fig. 9(B), the hydrogen production rate of PCOFR varies when dealing with these three types of chlorophenol organic compounds. This may be because the concentration of pollutants varies, and the degradation rate of different organic compounds may also vary. In addition, the influence of organic matter types may also lead to differences in hydrogen production efficiency. In summary, PCOFR has a good degradation effect on chlorophenol organic compounds, but its degradation efficiency and hydrogen production rate may vary when dealing with different organic compounds.
Degradation effect of chlorophenol organic compounds ((A) shows the adsorption and degradation rates of three chlorophenol organic compounds; (B) shows hydrogen production rate).
Figure 10 shows the degradation of three chlorophenol pollutants by PCOFR to produce CO2. Figure 10(A) is a graph of the rate at which three chlorophenol pollutants are degraded to produce CO2. Figure 10(B) is the trend chart of CO2 generation. Analyzing the data in Fig. 10, it can be seen from the trend that after PCOFR degrades three chlorophenol pollutants, the most CO2 generated is 2-CP, followed by 2,4-DCP, and the least is 2,4,6-TCP. This corresponds to their degradation rate, and organic compounds with high degradation rates also produce relatively more CO2. Therefore, PCOFR can evaluate the degradation effect of chlorophenol pollutants by detecting the amount of CO2 produced. This study can degrade different types of POPs by changing the type of photocatalyst in PCOFR, which is in line with the research hypothesis.
PCOFR for the degradation of three chlorophenol pollutants to produce CO2 ((A) shows the degradation rate chart of three chlorophenol pollutants to produce CO2; (B) shows trends in the degradation of three chlorophenol pollutants to produce CO2).
POPs in aquatic environments may sometimes involve metal ions. These metal ions may interact with POPs or form complexes in the aquatic environment, thereby affecting their chemical behavior and toxicity. Therefore, when studying and evaluating POPs in aquatic environments, it is necessary to consider the presence and potential effects of these metal ions. After the water environment POPs monitoring and treatment system, the comparison of metal ion concentrations in the inlet and outlet water is Table 1. According to the provided data, the water environment POPs monitoring and treatment system has significantly reduced the concentration of heavy metal ions in the water environment. Specifically, the concentration of Ag2+ decreased by 83.9%, the concentration of Cd2+ decreased by 99.1%, the concentration of Cr decreased by 99.8%, the concentration of Cu2+ decreased by 98.3%, the concentration of Hg2+ decreased by 99.9%, the concentration of Ni2+ decreased by 99.9%, and the concentration of Pb2+ decreased by 88.6%. The results indicate that the treatment system effectively removes heavy metal ions from water, which is of great significance for the protection of the water environment and the treatment of POPs. Reducing the concentration of heavy metal ions can help reduce potential risks to ecosystems and human health.
;%0A%09%09%09newWindow.document.open();%0A%09%09%09newWindow.document.write('<img src=%22./Graphics/MT-N2024004tab01.jpg%22>');%0A%09%09%09newWindow.document.close();%0A%09%09)
The monitoring and treatment system for water environment POPs has shown the removal effect of chemical oxygen demand (COD) and suspended solids in Fig. 11. In Fig. 11, the water environment POPs monitoring and treatment system performs well in sewage treatment, effectively reducing the organic matter content in the waste liquid and achieving a COD removal rate of 90%. This means that the system can effectively reduce the pollution of waste liquid to the environment and help protect the health of aquatic ecosystems. In addition, the system can effectively remove suspended solids from the waste liquid, making it clearer. The removal rate of suspended solids reaches 80%, further reducing solid pollutants in wastewater and improving water environment quality. The research results are in line with expectations, the monitoring and treatment system for persistent organic pollutants in water environment can effectively reduce the concentration of heavy metal ions in water, thereby reducing potential risks to ecosystems and human health [14]. In addition, the system can effectively remove organic matter and suspended solids from waste liquid, improving the quality of water environment. These results indicate that the system performs well in waste liquid treatment, contributing to the protection of water environment health and sustainable development.
Monitoring and governance system’s effectiveness in removing COD and suspended solids ((A) shows the COD removal effect; (B) shows the Removal effect of suspended solids).
Compared to previous studies, the results of this study have shown significant improvements in degradation efficiency, reduction of heavy metal ion concentration, and removal rate of suspended solids. Firstly, the degradation efficiency of PCOFR for three types of chlorophenol organic compounds reached 93%, 86%, and 83%, significantly improving compared to the previous degradation efficiency of around 80% [15, 16]. Secondly, the concentration of heavy metal ions in the water significantly decreased after PCOFR treatment. In addition, the removal rate of suspended solids in water after PCOFR treatment has also been significantly improved. By analyzing the Ti3C2/ZnCo2O4/ZnIn2S4 composite material using EDS surface scanning technology, it can be concluded that the composite material has excellent photocatalytic performance. At the same time, the composite material can effectively remove organic matter and suspended solids in water, thereby improving water quality [17]. These results indicate that PCOFR technology has good application prospects in treating POPs in water environments, and can promote green and sustainable development of the environment and scientific progress.
This study synthesized a new type of photocatalyst Ti3C2/ZnCo2O4/ZnIn2S4 and applied it to PCOFR to remove POPs from water. The prepared Ti3C2/ZnCo2O4/ZnIn2S4 composite material had excellent photocatalytic performance and stability, and could be used as an efficient catalyst for hydrogen production reactions. At the same time, a water environment POPs monitoring and governance system was designed using IoT technology. The experimental results showed that the system had a high degradation effect on chlorophenol organic compounds, significantly reducing the concentration of heavy metal ions, and effectively improving water quality. Through experimental verification, the degradation efficiency of PCOFR for three types of chlorophenol organic compounds reached 93%, 86%, and 83%, respectively, and the hydrogen production rate was 27369 µmol/h/g, 24087 µmol/h/g and 18694 µmol/h/g, respectively. Research had found that the water environment POPs monitoring and treatment system had significantly reduced the concentration of heavy metal ions, such as Ag2+, Cd2+, Cr, Cu2+, Hg2+, Ni2+, and Pb2+, which have decreased by 83.9%, 99.1%, 99.8%, 98.3%, 99.9%, 99.9%, and 88.6%, respectively. At the same time, the system had a significant removal effect on COD and suspended solids, with a COD removal rate of 90% and a suspended solids removal rate of 80%. The results indicated that the Ti3C2/ZnCo2O4/ZnIn2S4 composite photocatalyst developed and its application in water environment POPs monitoring and treatment systems had high performance and practicality. It provided scientific basis and technical support for water environment protection and governance. However, this study still has certain limitations, and future research can optimize the preparation methods of photocatalysts, improve their photocatalytic performance, broaden their application fields, and achieve more efficient and environmentally friendly water treatment technologies.
This work was supported by Construction technology of excavation station with large section under soft surrounding rock condition (k22-Guide-105).
