CN106323689B - A Water Quality Monitoring-Oriented Trap for Trace Polar Organic Pollutants - Google Patents

Abstract

The invention relates to a cumulative sampling device which can be used for monitoring the concentration of polar organic pollutants in water with a composite characteristic adsorbent as an acceptor phase. The device is based on synthetic polymer membrane materials and mixed-mode solid-phase extraction adsorbents. The composite adsorbent is placed between two layers of polymer membranes to form a sandwich structure sampler, which can simultaneously enrich various polarities in water. Organic Pollutants. Aiming at the difference of polar organic pollutants in water, the present invention selects five characteristic solid-phase extraction adsorbents to form mixed-mode adsorbents, which have reversed-phase adsorption, weak anion exchange and weak cation exchange with increased polarity range at the same time. , has a broad-spectrum adsorption effect on polar organic pollutants in water; at the same time, a polymer permeable membrane with a specific pore size range is selected as the outer membrane, which can ensure the free passage of water, free dissolved and colloidal compounds, and shorten the adsorption equilibrium time. It can be used as a balanced sampler for monitoring trace organic pollutants in water and biological simulation sampling.

Description

A Water Quality Monitoring-Oriented Trap for Trace Polar Organic Pollutants

technical field

The invention relates to a capture device for enriching and monitoring polar organic pollutants in water with a composite characteristic adsorbent as a receiving phase. Due to the limitation of the pore size of an external polymer membrane, only two kinds of free dissolved state and colloidal state are allowed. The polar organic pollutants in the form enter the trap and are adsorbed, which truly reflects the biologically available concentration of polar organic pollutants in water. It can be used to simulate biological monitoring, evaluate the ecotoxicological effects of polar pollutants, and screen " Prioritize the control of pollutants” and rationally manage the use and discharge of polar pollutants.

Background technique

The invention relates to a capture device for enriching and monitoring polar organic pollutants in water with a composite characteristic adsorbent as a receiving phase. Due to the limitation of the pore size of an external polymer membrane, only two kinds of free dissolved state and colloidal state are allowed. The polar organic pollutants in the form enter the trap and are adsorbed, which truly reflects the biologically available concentration of polar organic pollutants in water. It can be used to simulate biological monitoring, evaluate the ecotoxicological effects of polar pollutants, and screen " Prioritize the control of pollutants” and rationally manage the use and discharge of polar pollutants.

Active sampling technology

Active sampling technology is the most common technology for collecting and extracting pollutant residues in water. The application of active sampling technology requires additional power to complete the sample collection during the sample collection process. Liquid-liquid extraction and solid-phase extraction are two typical active sampling methods. The concentration of pollutants collected by liquid-liquid extraction is the total concentration of chemicals in the sample, which cannot accurately distinguish the compounds in the bioavailable and bioavailable forms in the environment, and the consumption of organic solvents is large. In order to solve the shortcomings of liquid-liquid extraction, researchers have developed solid-phase extraction methods, including solid-phase extraction disks. This method uses suction filtration or pump pressure to pass water samples through a cylindrical container filled with polymer materials.

When the active sampling technology is used for sample collection and extraction, if the water sample is relatively turbid, the sample generally needs to be filtered through a glass fiber filter before passing through the adsorbent filler, which takes a long time to filter. In addition, target contaminants are subject to loss of contaminants during sample storage due to volatilization, adsorption to storage vessel walls, and chemical degradation. Moreover, the pollutant concentration obtained by the active sampling method can only reflect the pollutant status at the time of sampling, and this sampling method is easily affected by the pulsed input of pollutants. Furthermore, trace analysis and biotoxicity testing studies require collection and processing of large volumes of samples, which are time-consuming and labor-intensive. Although some researchers have used a large-volume solid-phase extraction sampling system, there are still inevitable problems with the solid-phase extraction method, and using a large-volume sampling system when multiple sampling points are required is more time-consuming and labor-intensive, and the investment cost is high. .

passive sampling technique

Passive is relative to active, that is, a passive method for sample collection and pollutant extraction that does not require external power or energy. The acquisition or concentration of pollutants by passive sampling technology is completely based on the process of automatic diffusion of chemicals from high chemical potential or high fugacity to low chemical potential or low fugacity. Target pollutants can enter organic compounds by passive diffusion along the chemical potential difference. Mutually. Compared with active sampling technology, passive sampling technology is closer to the enrichment method of pollutants in biological organisms.

Since the development of passive sampling technology for many years, the current passive sampling technology for organic pollutants in the water environment mainly includes but is not limited to semi-permeable membrane sampling device (SPMD), solid phase microextraction device (SPME), solid phase extraction disk (ED) , polyethylene sampling devices (PEDs) and polyoxymethylene sampling devices (POM). SPMD is a semi-permeable membrane made of low-density polyethylene (LDPE) filled with triolein and other substances. Organic pollutants in the water will pass through the semi-permeable membrane and be adsorbed by lipids in the membrane. SPMD has been successfully used in water Determination of hydrophobic organic matter in the environment, and simulate the determination of the bioconcentration process of aquatic organisms. SPME sampling is usually achieved by stirring to achieve the distribution equilibrium of the target pollutants on the water phase and SPME phase as soon as possible, so as to realize the extraction process of the target pollutants. These passive samplers are widely used to simulate organisms to predict the bioaccumulation behavior and bioavailability of hydrophobic organic pollutants in environmental media.

The enrichment phase in the above passive sampling techniques and devices is a polymer organic phase, which is generally weak in polarity and basically completes the extraction process based on the principle of "similar compatibility". The measurement is not suitable for polar or hydrophilic organic pollutants. Although there are reports that researchers use it for the determination of polar organic pollutants, the results are not ideal. In recent years, the research of pharmaceuticals and personal care products has been paid more and more attention, and the sampling technology for these polar organic pollutants (such as polar organic pollutant accumulation sampler, POCIS) has attracted more and more attention, and is widely used in water Monitoring of estrogens, antibiotics and non-antibiotics in the environment. The cumulative sampling technology of polar organic pollutants has a strong binding force to polar organic pollutants, which can well solve the problems of long sampling and enrichment time and rich accumulation of other passive sampling technologies when collecting and extracting polar organic pollutants. Insufficient collection and so on.

The microporous hydrophilic membrane used in traditional POCIS technology is generally a polyethersulfone material with a pore size of 0.1 microns. During use, it was found that due to the small pore size of 0.1 microns, when the target was extracted by the inner enrichment phase through the outer membrane The resistance is very large, resulting in a small extraction rate. After 28 days of exposure, the target substance is still in the linear enrichment stage in the sampler, and the distribution balance has not been reached. There are a series of problems such as large deviation and long time. The 0.1-micron pore size only allows free dissolved polar organic pollutants to enter the sampler and cannot collect colloidal polar organic pollutants. The colloidal state in natural water is an important form of polar organic pollutants, and it also has Bioavailability. In addition, due to long-term sampling in natural water bodies, biofouling is prone to occur. The adsorbent used in the traditional POCIS sampler is mainly Oasis HLB adsorbent, which uses the principle of reversed-phase adsorption to collect polar and non-polar organic pollutants in water. Because it takes into account both hydrophilicity and lipophilicity, and only based on a single reversed-phase adsorption Therefore, the adsorption range and adsorption efficiency of polar organic pollutants are not high. At present, the passive sampling technology of polar organic pollutants developed by the mechanism of mixed adsorption mode (reversed-phase adsorption and ion-exchange adsorption) has not been reported.

SUMMARY OF THE INVENTION

The principle of the present invention (economical and efficient accumulation sampling technology for polar organic pollutants) is: by selecting a hydrophilic polymer permeable membrane with a suitable pore size range as the outer membrane, combined with a specific composite adsorbent as the enrichment phase, not only guarantees The sampler can enrich and extract broad-spectrum polar organic pollutants in the water environment, and greatly shorten the sample collection time, improve the enrichment amount and analysis sensitivity, effectively avoid the biofouling phenomenon of the sampler, and reduce the sampling rate. Cost, and then can effectively achieve simulated biological monitoring and ecological risk assessment.

In the present invention, a larger pore size permeable membrane is used in the hydrophilic membrane, which can effectively enrich and extract most polar organic pollutants distributed in the true dissolved phase and the hydrocolloid phase, improve the sampling rate, and make the typical polar organic pollutants The enrichment balance of sexual pollutants can be reached within 2 weeks, which is convenient for calculating the concentration of pollutants in water.

In the selection of the adsorbent for the enriched phase, the present invention fully considers the expandability of the sampler, the scope of application, the cost of use and other factors, and selects five kinds of solid-phase extraction adsorbents as the accepting phase: polystyrene-divinylbenzene resin ( It is suitable for adsorbing polar analytes such as antibiotics that are not retained enough on C18 or C18 adsorbents), pyrrolidone-bonded polystyrene-divinylbenzene resin (on the basis of polystyrene/divinylbenzene resin, bonded with Pyrrolidone, which enhances the surface polarity, achieves a hydrophilic-lipophilic balance, and is suitable for the extraction of polar and non-polar substances), a solid polymer with anion-exchange groups modified on pyrrolidone-bonded polystyrene-divinylbenzene resin Phase extraction adsorbent (can extract a variety of acidic and basic substances without adjusting the pH value), solid phase extraction adsorbent modified with cation exchange groups on pyrrolidone-bonded polystyrene-divinylbenzene resin (enhanced The adsorption performance of weak alkaline substances), graphitized carbon black (strong adsorption of polar substances). In order to allow the sampler to absorb as many polar organic pollutants as possible in one extraction process, the present invention mixes the above five filler adsorbents in a certain proportion and by certain means, so that the composite adsorbent also has The reversed-phase adsorption, weak anion exchange and weak cation exchange with the increased polarity range realize mixed-mode solid-phase extraction adsorption, which has better selectivity and extraction efficiency than the single adsorption mode sampler.

The advantages of the present invention (polar organic pollutant accumulation sampling technology and sampler):

The principle of sampling technology and the production of the sampler are simple. On the basis of future research, a hydrophilic polymer permeable membrane with a larger pore size is used, and a composite characteristic adsorbent with a wide range of applications and economical feasibility is selected to realize mixed-mode solid-phase extraction and adsorption. Passive sampling technology and sampler that can achieve efficient enrichment and extraction of various polar organic pollutants in the water environment, low cost of sampler production and use, wide range of enrichment and extraction target pollutants, enrichment time Short, high enrichment efficiency, high analytical sensitivity, effectively avoiding the biofouling of the sampler.

In the sampling technology of the present invention, the target pollutant can quickly reach the distribution balance in the sampler, and the sampler is used as a balance sampler, which is more convenient to calculate the environmental concentration of the target pollution in the measured water body.

Therefore, the sampling technology of the present invention improves the conventional polar organic pollutant accumulation sampling technology, is more favorable for monitoring polar organic pollutants in the water environment, simulates biological monitoring and evaluates ecological risks, and has great scientific significance.

Description of drawings

Figure 1 is a schematic structural diagram of a polar organic pollutant trap.

Figure 2 is a schematic diagram of the enrichment kinetics of sulfapyridine in a polar organic pollutant trap in an on-site exposure experiment of a sewage treatment plant.

Figure 3 is a schematic diagram of the enrichment kinetics of sulfamethoxazole in the field exposure experiment of a polar organic pollutant trap in a sewage treatment plant.

Figure 4 is a schematic diagram of the enrichment kinetics of ketoprofen by polar organic pollutant traps in an on-site exposure experiment of a sewage treatment plant.

Figure 5 is a schematic diagram of the enrichment kinetics of thiamphenicol in the field exposure experiment of a polar organic pollutant trap in a sewage treatment plant.

Figure 6 is a schematic diagram of the enrichment kinetics of ofloxacin by polar organic pollutant traps in the field exposure experiment of a sewage treatment plant.

Detailed ways

In order to better understand the content of the present invention, the present invention is further described with reference to the accompanying drawings and implementation cases, but the examples do not limit the protection scope of the present invention.

The present invention (polar organic pollutant trap) has been placed in a sewage treatment plant in Shanghai for on-site experiments, and it was taken out for elution after 1 day, 3 days, 5 days, 7 days, 14 days, 21 days and 28 days of placement. analyze. The invention can enrich more than ten kinds of pharmaceutical polar pollutants at the same time, and can enrich the organic substances that cannot be enriched by the active sampling method (solid phase extraction). It can be seen from the accumulated enrichment concentrations of the five polar drugs with high detection rates, sulfapyridine, sulfamethoxazole, ketoprofen, flumethiamycin and ofloxacin, that these five pollutants are all The enrichment equilibrium can be reached within 4 weeks or even shorter time (see Figures 2, 3, 4, 5, and 6 in the description for details).

Example 1: Enrichment kinetics experiment of typical PPCPs drugs in water by polar organic pollutant traps

A large-scale urban sewage treatment plant in Shanghai is selected, a point is arranged in the water treatment process section, and the sampling device of the present invention is suspended in the water for 1 day, 3 days, 5 days, 7 days, 14 days, 21 days respectively. Days and 28 days later were removed for elution analysis. The invention can enrich more than ten kinds of pharmaceutical polar pollutants at the same time, and can enrich the organic substances that cannot be enriched by the active sampling method (solid phase extraction). The cumulative enrichment concentrations of five polar drugs with high detection rates, sulfapyridine, sulfamethoxazole, ketoprofen, flumethicone and ofloxacin (Fig. 2, 3, 4, 5, 6) It can be seen that these five pollutants can reach the enrichment equilibrium within 4 weeks or even shorter time.

Example 2: Broad-spectrum adsorption verification experiment of polar organic pollutant trap

Take the polar organic pollutant trap on the 28th day in Example 1, analyze the polar organic pollutants adsorbed by it, and take 5L of water samples on the 28th day, and transport them back to the laboratory for enrichment by solid phase extraction. , concentration and determination. The polar organic pollutants detected by the two methods were compared. Table 1 shows the comparison of the implementation steps of the solid-phase extraction and polar organic pollutant trap methods and the comparison results of the differences in the types of pollutants screened.

Table 1 Comparison of the list of pharmaceutical pollutants screened by different monitoring methods in an urban sewage plant

As can be seen from the above table, the polar organic pollutant trap sample pretreatment process is simpler, and more types of pollutants can be detected.

Claims (3)

1. A polar organic pollutant catcher in water environment is characterized in that: the device comprises two filter membranes, a composite characteristic adsorbent, two stainless steel compression rings and stainless steel fixing screws, wherein the adsorbent is placed between the two filter membranes, the filter membrane is placed between the two compression rings, the two compression rings and the two filter membranes are fixed together by the screws to form a multilayer composite sandwich structure, and the composite characteristic adsorbent is arranged at the central position of an inner ring of a stainless steel compression ring and cannot flow out from between the compression rings to be lost; the composite characteristic adsorbent is prepared by five solid phase extraction adsorbents, namely polystyrene-divinylbenzene resin, pyrrolidone bonded polystyrene-divinylbenzene resin, solid phase extraction adsorbent which is modified with anion exchange groups on the pyrrolidone bonded polystyrene-divinylbenzene resin, solid phase extraction adsorbent which is modified with cation exchange groups on the pyrrolidone bonded polystyrene-divinylbenzene resin and graphitized carbon black according to a proportion; wherein the filter membrane adopts a hydrophilic macromolecule permeable membrane with the aperture range of 0.45-1.0 μm.

2. The polar organic pollutant trap for use in an aqueous environment of claim 1 further comprising: the pressure ring is made of stainless steel.

3. The polar organic pollutant trap for use in an aqueous environment of claim 1 further comprising: the composite characteristic adsorbent is prepared by processing five solid phase extraction adsorbents, namely polystyrene-divinylbenzene resin, pyrrolidone-bonded polystyrene-divinylbenzene resin, solid phase extraction adsorbent with anion exchange groups modified on the pyrrolidone-bonded polystyrene-divinylbenzene resin, solid phase extraction adsorbent with cation exchange groups modified on the pyrrolidone-bonded polystyrene-divinylbenzene resin and graphitized carbon black to form mixed mode solid phase extraction adsorbent, and then proportionally configuring according to the property of the monitored target pollutant.

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