Method for removing bisphenol S from water by using sunlight combined with carbonate to activate peroxymonosulfate

Abstract

The present invention relates to a method for removing bisphenol S in water by using sunlight combined with carbonate to activate permonosulfate, that is, adding carbonate and permonosulfate to the bisphenol S-contaminated wastewater to be treated, fully stirring and mixing, and then irradiating with sunlight to achieve degradation of bisphenol S. The sunlight / carbonate / permonosulfate system established by the present invention can make full use of the alkaline buffering effect of carbonate, so that the pH value of the solution is stably maintained at a high level, greatly improves the light absorption efficiency of permonosulfate and bisphenol S, promotes the generation of singlet oxygen and superoxide radicals, and achieves the purpose of rapid degradation of bisphenol S. The present invention does not require additional energy supply, greatly reduces the cost, has the advantages of efficient degradation of bisphenol S, environmental friendliness, etc., and has broad application prospects in ensuring water ecological safety.

Description

Technical Field

[0001] The invention relates to a method for removing bisphenol S in water by using sunlight combined with carbonate to activate peroxymonosulfate, and specifically belongs to the technical field of wastewater treatment. Background Art

[0002] Bisphenol S (BPS) is one of the important raw materials for industrial production and is widely used in the manufacture of polycarbonate plastics, epoxy resins in food can linings, baby bottles, and thermal paper. However, BPS is considered a typical emerging pollutant and endocrine disruptor with potential toxicity, which may lead to decreased sperm quality in men, infertility in women, liver damage, and neurological dysfunction. BPS is more stable than other bisphenols and is therefore more difficult to degrade. Traditional water treatment technologies have limited removal effects on BPS, resulting in a high detection rate in various environmental matrices (such as surface water, groundwater, and soil sediments). Studies have shown that the concentration of BPS in China's Taihu Lake increased from 67 ng / L in 2013 to 160 ng / L in 2016. Moreover, due to its longer half-life, BPS will flow through the water cycle throughout the country and even be transferred to the ocean, causing wider pollution. Therefore, it is imperative to explore an efficient and environmentally friendly method for removing BPS.

[0003] At present, the methods for the treatment of bisphenol pollution mainly include biodegradation, adsorption degradation and oxidative degradation. However, no research has shown that BPS can be directly biodegraded. In addition, adsorption degradation may take a long time or require more expensive materials to synthesize, and the adsorption removal rate may not achieve the expected effect. Therefore, traditional methods are not suitable for efficient degradation of BPS.

[0004] Advanced oxidation processes (AOPs) based on free radicals have been widely used to degrade biorefractory organic pollutants in wastewater. In recent years, AOPs using peroxymonosulfate (PMS) as an oxidant have become a hot topic of research. The structure of PMS is similar to that of the traditional Fenton oxidant hydrogen peroxide (H2O2), but the redox potential of PMS is higher than that of H2O2, and the energy required for activation is lower. In addition, PMS is a stable, non-toxic, inexpensive and highly soluble solid potassium salt that is easier to transport and store than liquid H2O2. Although PMS is oxidizing, its reaction rate with organic pollutants is average and usually requires external energy or chemical consumption, such as heating, ultraviolet (UV), ultrasound, transition metals or carbon-based materials. However, most of the use of UV or thermal activation has some limitations, such as unsatisfactory activation performance, high cost, and huge energy consumption. Heavy metal activation will produce heavy metal pollution and increase the risk of secondary pollution, high risk of metal dissolution (transition metal ions / metal oxides), etc., which limits its actual environmental application.

[0005] Compared with UV, solar energy is a clean and economical renewable energy. Therefore, the use of sunlight (solar) to activate PMS has become a research hotspot. However, there are still limitations to the widespread application of solar / PMS systems. The molar extinction coefficient of PMS is very low in the wavelength range of sunlight, and it is almost impossible to absorb photons from sunlight. In addition, according to the Planck equation, only light with a wavelength less than 317nm can destroy the peroxide bond (OO) in PMS because of its high bond dissociation energy (377kJ / mol), which further limits the possibility of PMS being directly activated by sunlight. Some studies have shown that photocatalysts such as TiO2 and CoFe2O4 can effectively activate PMS under solar radiation. However, these catalysts are expensive and require complex preparation methods. Degrading pollutants without any catalyst may be an environmentally friendly and cost-effective method. Studies have shown that under alkaline conditions, the morphology of pollutants and PMS may change, and their absorption spectra may undergo red shifts, which leads to higher solar light absorption capacity. On the one hand, under alkaline conditions, the photolysis rate of PMS can be significantly increased. On the other hand, under alkaline conditions, the target pollutants exist mainly in anionic form, which are generally relatively more reactive compared to protonated or uncharged molecules. In addition, previous studies have shown that organic pollutants can act as photosensitizers, thereby being excited to form reactive intermediates, such as the excited triplet state of the pollutant (P*), which can further react with PMS to generate other ROS via electron transfer. Carbonate (CO3 2− ) is an alkaline, non-toxic substance that is cheap and easily available. Wu Leliang et al. tried to add CO3 2− To degrade BPS in water, the system has limited ability to remove BPS and the reaction time is too long. The results show that after 10 hours of reaction, the degradation rate of BPS is only 90.12%, and the degradation effect of this system on BPS in actual water is not good, and it is strongly inhibited, which needs further improvement. Therefore, by adding CO3 to the wastewater containing BPS 2− and PMS and irradiated with sunlight, it is expected that BPS will be removed quickly and efficiently. Summary of the invention

[0006] The present invention aims to provide a method for activating peroxymonosulfate by combining sunlight with carbonate (solar / CO3 2− The present invention does not require expensive oxidants and catalysts, can utilize natural sunlight to oxidatively degrade BPS, is easy to operate, and can remove BPS from polluted water in an efficient, stable, economical and environmentally friendly manner.

[0007] To achieve the above technical objectives, the method of removing bisphenol S in water by sunlight combined with carbonate activation of permonosulfate of the present invention degrades bisphenol S in wastewater under room temperature conditions by irradiating with sunlight, using carbonate as an alkaline buffer and permonosulfate as an oxidant. The specific steps are as follows:

[0008] Step 1: adding carbonate to wastewater containing bisphenol S to obtain a mixed solution;

[0009] Step 2: adding peroxymonosulfate to the mixed solution and irradiating the mixture with sunlight to obtain wastewater from which bisphenol S has been removed.

[0010] The carbonate is sodium carbonate.

[0011] The peroxymonosulfate is potassium peroxymonosulfate.

[0012] The concentration of the sodium carbonate in the wastewater is 0.5-5 mM.

[0013] The concentration of potassium permonosulfate in wastewater is 0.5-5 mM.

[0014] The wavelength of the sunlight is 290-800nm.

[0015] The sunlight irradiation time is 5 to 120 minutes, and the stirring speed is 100 to 300 revolutions per minute.

[0016] The present invention has the beneficial effects:

[0017] 1. The purpose of the present invention is to introduce CO3 into the solar / PMS system 2− , forming solar / CO3 2− The composite system of solar / PMS can enhance the removal of organic pollutants in water by solar / PMS. It is simple to operate, has mild reaction conditions, low energy consumption, and can prevent toxic metal ions from entering the ecosystem to cause secondary pollution. It is economical and environmentally friendly, has strong adaptability, and has broad application prospects.

[0018] 2. The present invention has a high removal efficiency of BPS in water. For example, after treating the polluted water for 120 minutes, the removal rate of bisphenol S can reach 98.06%.

[0019] 3. CO3 used 2− It is inexpensive, safe and stable, easy to store and transport, and has a buffering effect. Its use can also avoid the problem of acidification of water after treatment.

[0020] 4. Since sunlight is a green, clean and sustainable light source, the present invention can directly utilize natural sunlight, which is simple to operate, environmentally friendly and low-cost, and basically has no safety hazards. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The degradation curves of BPS under different systems under sunlight of the present invention are shown;

[0022] Figure 2 is the UV-visible spectrum of BPS under different conditions of the present invention;

[0023] Figure 3 The contribution of different reactive oxygen species in the degradation of BPS in the present invention;

[0024] Figure 4 For the solar / CO3 2− / Electron paramagnetic resonance spectrum of PMS system;

[0025] Figure 5 For the solar / CO3 2− / PMS system degradation curve of BPS in different types of water bodies. DETAILED DESCRIPTION

[0026] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0027] Example 1

[0028] This embodiment utilizes CO3 2− The method for promoting sunlight-activated PMS to degrade BPS is achieved by the following steps:

[0029] Under the condition of temperature (25±1℃), the initial concentration of BPS C0 was 20μM, and PMS and CO3 2− The dosage concentration ratio was 1:3 (1mM:3mM). After sufficient stirring, the mixture was placed under sunlight (16.7mW / cm 2 ). The concentration C of BPS in the system at different reaction times was detected, and the degradation of BPS within 120 minutes was obtained.

[0030] Control group 1 (solar only): at a temperature of 25 ± 1 °C, the initial concentration of BPS C0 was 20 μM, and the total volume of the system was 40 mL. After sufficient stirring, the system was placed under sunlight (16.7 mW / cm 2 ). The concentration C of BPS in the system at different reaction times was detected, and the degradation of BPS within 120 minutes was obtained.

[0031] Control group 2 (PMS alone): Under the condition of temperature (25±1℃), add 1mM PMS to the BPS water sample with an initial concentration C0 of 20μM, and stir it thoroughly while ensuring that the total volume of the system is 40mL. Detect the concentration C of BPS in the system at different reaction times, and obtain the degradation of BPS within 120 minutes.

[0032] Control group 3 (CO3 alone 2− ): At a temperature of 25 ± 1 ° C, add 3 mM CO3 2− Added to the BPS water sample with an initial concentration C0 of 20 μM, and fully stirred while ensuring that the total volume of the system was 40 mL. The concentration C of BPS in the system at different reaction times was detected to obtain the degradation of BPS within 120 minutes.

[0033] Control group 4 (solar / PMS): Under the condition of temperature (25±1℃), add 1mM PMS to the BPS water sample with an initial concentration C0 of 20μM, and after fully stirring, place it under sunlight while ensuring that the total volume of the system is 40mL. Detect the concentration C of BPS in the system at different reaction times, and obtain the degradation of BPS within 120 minutes.

[0034] Control group 5 (solar / CO3 2− ): At a temperature of 25 ± 1 ° C, add 3 mM CO3 2− Add the BPS water sample with an initial concentration C0 of 20 μM, and after sufficient stirring, place it under sunlight while ensuring that the total volume of the system is 40 mL. Detect the concentration C of BPS in the system at different reaction times and obtain the degradation of BPS within 120 minutes.

[0035] Control group VI (PMS / CO3 2− ): Under the condition of temperature (25±1℃), add 1mM PMS and 3mM CO3 2− Add the BPS water sample with an initial concentration C0 of 20 μM, and stir it fully while ensuring that the total volume of the system is 40 mL. Detect the concentration C of BPS in the system at different reaction times and obtain the degradation of BPS within 120 minutes.

[0036] from Figure 1 It can be seen that when using solar, PMS and CO3 alone 2− When the water samples were treated, the BPS removal rates were 3.32%, 2.21% and 1.83% respectively. 2− System and PMS / CO3 2−When the system degrades BPS, the degradation rates can reach 13.49%, 9.41% and 13.69%. It is worth noting that sunlight, CO3 2− The combination of chlorinated polyol and PMS has an excellent degradation effect on BPS in aqueous solution, with a degradation rate of up to 98.06%. Figure 2 It can be seen that BPS does not absorb any light at wavelengths greater than 320nm. However, the addition of PMS and CO3 2− After that, the absorption spectrum of BPS red-shifts and the molar absorptivity is higher. Therefore, under alkaline conditions, the interaction between BPS and PMS leads to the absorption of sunlight, which accelerates the generation of reactive oxygen species (ROS) and the degradation of BPS. Under sunlight irradiation, BPS can be excited to BPS*, which will further react with oxidants to form other ROS, such as singlet oxygen ( 1 O2) and superoxide radicals (O2 •− ).

[0037] (1)

[0038] (2)

[0039] (3)

[0040] (4)

[0041] (5)

[0042] (6)

[0043] (7)

[0044] Example 2

[0045] In this example, PMS and CO3 2− Effect of addition molar ratio on BPS degradation rate.

[0046] Taking Example 1 as a reference, the only difference is that the concentration of PMS in the mixed solution is changed to 0.5, 1, 1.5, 2, 3, and 5 mM. After 120 minutes, the degradation rates of BPS are 12.60%, 84.92%, 98.06%, 100.00%, 100.00%, 100.00%, and 97.00%, respectively.

[0047] Example 3

[0048] Take Example 2 as a reference, the only difference is changing CO3 2−The concentrations were 0, 0.5, 1, 2, 3, and 5 mM, that is, without adding CO3 2− , and PMS / CO3 2− When the molar concentration ratios were 2, 1, 0.5, 0.33, and 0.25, the BPS degradation rates reached 13.50%, 22.99%, 77.35%, 89.83%, 98.06%, and 95.33% after 120 minutes, respectively.

[0049] Example 4

[0050] At temperature (25 ± 1 ° C), BPS, PMS and CO3 were added to the water sample. 2− , ensuring that their initial concentrations C0 were 20μM, 1mM and 3mM respectively. Under the premise of ensuring that the total volume of the system was 40mL, quenchers of different active substances were added, ascorbic acid 10mM (quencher of all ROS), methanol 10mM (corresponding to ROS as sulfate free radical SO4 •− and hydroxyl radicals HO•), tert-butyl alcohol 10mM (corresponding to ROS is HO•), histidine 5mM (corresponding to ROS is 1 O2), 0.1mM nitroblue tetrazolium (corresponding to ROS is O2 •− ).like Figure 3 As shown, solar / CO3 2− / PMS system ROS has 1 O2 and O2 •− , the most important role is played by 1 O2.

[0051] Example 5

[0052] Under the condition of temperature (25±1℃), the initial concentration of bisphenol S (BPS) C0 is 20μM, and the total volume of the system is 40mL. 2− The concentration ratio was 1:3 (1mM:3mM), and samples were taken after 120 minutes of reaction under sunlight and dark conditions. The free radical scavenger 2,2,6,6-tetramethyl-4-piperidone (TEMP) was added, and the generation of free radicals was analyzed using an electron paramagnetic resonance spectrometer. Figure 4 As shown, the electron paramagnetic resonance spectrum shows 1 O2 signal, and as sunlight is introduced into CO3 2− / After the PMS system, 1 The intensity of the O2 signal increased significantly, which further proved that the solar / CO3 2 − The main ROS of the / PMS system are 1 O2.

[0053] Example 6

[0054] Solar / CO3 2− The applicability of the / PMS system to different types of water samples included the following steps: water samples were collected from Le'an River (Shangrao, China), Poyang Lake, and Yao Lake (Nanchang, China), as well as tap water samples collected in the laboratory, and BPS was added to obtain a BPS solution with an initial concentration of 20 μM to simulate actual water samples. Under the premise of ensuring that the total volume of the system was 40 mL, PMS and CO3 2− The dosage concentration ratio was 1:3 (1mM: 3mM), and after sufficient stirring, it was placed under sunlight. The concentration C of BPS in the system at different reaction times was detected, and the degradation of BPS within 120 minutes was obtained.

[0055] The results are as follows Figure 5 As shown, the solar / CO3 2− / PMS system can effectively remove BPS in water in actual water samples, which shows that solar / CO3 2− The / PMS system has high adaptability in actual water bodies and therefore has good application prospects.

[0056] The above description of the embodiments is to facilitate those skilled in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work.

Claims

1. A method for removing bisphenol S from water by using sunlight combined with carbonate to activate peroxymonosulfate, characterized in that: The method described degrades bisphenol S in wastewater under room temperature conditions by irradiating with sunlight, using carbonate as an alkaline buffer and peroxymonosulfate as an oxidant. The specific steps are as follows: Step 1: adding carbonate to wastewater containing bisphenol S to obtain a mixed solution; Step 2: adding peroxymonosulfate to the mixed solution and irradiating the mixture with sunlight to obtain wastewater from which bisphenol S has been removed; The carbonate is sodium carbonate, and the concentration of the sodium carbonate in the wastewater is 0.5-5 mM; The wavelength of the sunlight is 290-800nm.

2. The method for removing bisphenol S from water by using sunlight combined with carbonate to activate peroxymonosulfate according to claim 1, characterized in that: The peroxymonosulfate is potassium peroxymonosulfate.

3. The method for removing bisphenol S from water by using sunlight combined with carbonate to activate peroxymonosulfate according to claim 2, characterized in that: The concentration of potassium permonosulfate in wastewater is 0.5-5 mM.

4. The method for removing bisphenol S from water by using sunlight combined with carbonate to activate peroxymonosulfate according to claim 1, characterized in that: The sunlight irradiation time is 5 to 120 minutes, and the stirring speed is 100 to 300 revolutions per minute.

Images