CN114471514A

CN114471514A - Preparation method, application and modeling method of novel water body sediment catalyst

Info

Publication number: CN114471514A
Application number: CN202210147109.2A
Authority: CN
Inventors: 龙琭璐; 黄娜; 刘立寒; 羊蔚铭; 庞晗; 张赖敏
Original assignee: Sichuan Agricultural University
Current assignee: Sichuan Agricultural University
Priority date: 2022-02-17
Filing date: 2022-02-17
Publication date: 2022-05-13
Anticipated expiration: 2042-02-17
Also published as: CN114471514B

Abstract

The invention provides a preparation method, application and a modeling method of a novel water body sediment catalyst, which comprises the steps of collecting sediment samples from rivers, processing the sediment samples, and carrying out natural air drying for 2 weeks; step 2, selecting impurities of branches and weeds, freeze-drying for 48 hours, and labeling for later use; step 3, putting a certain amount of sediment sample in a 3mL crucible into a tubular furnace, heating to 700 +/-50 ℃ at the heating rate of 10 ℃/min in the air atmosphere, and calcining at constant temperature for 2h to prepare the catalyst for activating the PMS to degrade pollutants; and 4, degrading the organic matters by using the prepared catalyst for activating PMS to degrade pollutants and potassium persulfate. The invention provides a method for activating potassium persulfate to degrade organic matters by simply treating water body polluted sediments, and simultaneously, training 42 sediment samples by adopting a conventional regression mode, selecting an optimal regression model for modeling, and predicting the total carbon and organic matter content of the sediments through a degradation rate.

Description

Preparation method, application and modeling method of novel water body sediment catalyst

Technical Field

The invention belongs to the technical field of environmental protection, and particularly relates to a preparation method, application and a modeling method of a novel water body sediment catalyst.

Background

In recent years, due to rapid development of human activities and social economy, a large amount of exogenous pollutants enter rivers and lakes and are deposited in the lake bottom, so that a plurality of rivers and lakes are seriously polluted, and sediments become sources and sinks of the pollutants, so that the development of pollution control of the rivers and the lakes is very important, the sediments contain a large amount of resources, the generation amount of river sediment is increased year by year and the quantity of the river sediment is huge along with large-scale development of river water body environment treatment and dredging engineering, and the development of resource utilization of the river sediment has very important social and economic significance.

At present, various methods for resource utilization of sediments exist. Firstly, the dredged sediment is incinerated to generate electricity, and heat energy is converted into electric energy. Secondly, the sediment is used as a building material and is subjected to heat treatment to be used as a production raw material, so that the building material meeting various national standards is produced. In addition, the aggregate can be used as common concrete aggregate and can be made into slag broken stones, building blocks, pavement bricks and the like. Thirdly, a large amount of silicate materials in the sediment are utilized to prepare the ceramsite. The ceramsite is prepared by the processes of drying, crushing, screening, granulating, forming and the like, and has good mechanical properties, light weight and high strength. Fourthly, the river dredging sediment is used as a raw material to synthesize zeolite with a porous structure and more active sites to be used as an adsorbent to remove heavy metals in water. Fifth, the researchers of modifying the dredged sediment to prepare the catalyst mainly use metal elements such as iron in the sediment as the reaction sites of the catalyst for the treatment of sulfides in the atmospheric environment.

In recent years, some emerging pollutants which are difficult to degrade are widely concerned by researchers, and tetracycline antibiotics are one of typical emerging pollutants. The emergence of antibiotics has an indispensable role for the prevention and treatment of diseases, however, the improper use of antibiotics can lead to their remaining in the aqueous environment and soil. Tetracycline antibiotics accumulated in the aquatic ecosystem finally enter human bodies through food chains, and have potential hazards to human health and the environment. In order to reduce the harm of antibiotics to human body and environment, besides reducing the usage amount, a method for effectively removing antibiotics is required.

The existing methods for treating antibiotics mainly comprise conventional treatment methods (coagulation, precipitation and disinfection lamps), adsorption methods (activated carbon), membrane separation methods, chemical oxidation methods and the like. Among them, the chemical oxidation method is attracting attention due to its high efficiency and low cost. Compared with common chemical oxidation, based on^-OH and SO₄ ^2-Is an emerging technology developed in recent years for degrading novel organic pollutants, and mainly generates organic pollutants with extremely high activity by catalytically activating persulfate^-OH and SO₄ ^2-To degrade organic contaminants. At present, researchers prepare efficient catalysts to catalyze the decomposition of hydrogen peroxide or persulfate on the basis of a conventional Fenton reagent method, so that the generation amount and the generation rate of free radicals are improved, and the treatment efficiency of antibiotics in livestock wastewater and the effluent quality are improved.

At present, researchers have preliminarily explored various methods for recycling the sediments, such as sediment incineration power generation, although solid waste can be recycled, a large amount of combustion improver is needed, the requirement on temperature control is high, and air pollution can be caused; secondly, researchers use the sediment sintering products as building materials to prepare, certain economic value is reflected, but the defects of complex process, high energy consumption and the like exist, and organic matters existing in a large amount in the sediment are not effectively utilized. Thirdly, the ceramsite is prepared, but the available silicate component in the sediment is low, and the defects of high requirement on equipment in the production process and the like exist, so that the application of the ceramsite in industry is further limited. Fourthly, the adsorbent such as zeolite is prepared by modifying the adsorbent, but the prior modification process is complex, the cost is high, and the adsorption effect is not obvious.

The method for measuring the total carbon and organic matters of the sediments mainly refers to the measurement of corresponding indexes in soil. The total carbon of the deposit is measured by an infrared carbon-sulfur analyzer, a total carbon analyzer and an element analyzer. The organic carbon index is commonly used for indicating the content of organic matters in sediments, so as to judge the source of the organic matters, reflect the primary productivity condition of surface water and the input condition of terrestrial organic matters, and is an important index in sediment quality research. Potassium dichromate (K) in soil monitoring Specification NY/T112.1-2006₂Cr₂O₇) The method comprises the steps of measuring organic matters by an external heating method, keeping the temperature in an oil bath kettle at 170-180 ℃ in the presence of excessive sulfuric acid, boiling the solution for 5min, oxidizing organic carbon by using potassium dichromate serving as an oxidant, dripping the residual oxidant back by using a standard ferrous sulfate solution, calculating potassium dichromate consumed by the organic matters of the soil according to the residual amount, and calculating the organic matters of the soil. The dry burning method is used for measuring CO released after carbon in soil organic matters is oxidized₂Amount of the compound (A). The principle of the ignition method is to determine the soil weight loss caused by the ignition of carbon in soil organic matters. Weighing the soil sample without hygroscopic water at 105 ℃, then burning the soil sample at 350-1000 ℃ for 2h, and then weighing. The weight difference between the two times of weighing is the weight of soil organic matters in the soil sample. Most of the methods have the problems of complicated operation, large workload, high danger and the like.

The invention provides a method for recycling sediments, which is characterized in that sediments are modified to be used as a catalyst, the catalyst is used for quickly and effectively activating potassium hydrogen persulfate to degrade tetracycline in water, and meanwhile, a model for predicting the total carbon and organic matter content of the sediments in a quick, simple and convenient indirect mode is invented.

Disclosure of Invention

The invention aims to solve the defects in the prior art, provides a preparation method, application and a modeling method of a novel water body sediment catalyst, provides a model which can be used as a Fenton-like catalyst to activate potassium persulfate to degrade organic pollutants by simply treating water body pollution sediment, and provides a rapid, simple and convenient indirect mode for predicting the total carbon and organic matter content of the sediment.

The invention adopts the following technical scheme:

a preparation method of a novel water body sediment catalyst comprises the following steps:

step 1, collecting sediments from a river or lake, treating the sediments, and naturally airing for 2 weeks;

step 2, picking out branches and weeds in the collected sediments, and freeze-drying the collected sediments for 48 hours to obtain pretreated sediments, and labeling the pretreated sediments for later use;

and 3, putting a certain amount of the sediment obtained in the step 2 into a 3mL crucible, then placing the crucible into a tubular furnace, heating to 700 +/-50 ℃ at the heating rate of 10 ℃/min in the air atmosphere, and calcining for 2 hours at constant temperature to obtain the catalyst.

The application of a catalyst for novel water body sediment comprises the following steps:

the preparation method of the novel water body sediment catalyst is used, the prepared catalyst activates PMS to generate active substances to degrade organic pollutants, and the degradation rate D and the K value of a sample are calculated.

Specifically, 0.01g of the prepared catalyst is weighed in a 50mL beaker, the concentration of the catalyst is 0.2g/L, 50mL of 20ppm tetracycline TC is added, ultrasonic treatment is carried out for 5min, magnetic stirring is carried out for adsorption and balance for 20min, then 0.01g of PMS is added, and the mixture is mixed to be used for degrading organic matters.

A method of modeling total carbon and organic matter content of a predicted deposit, comprising:

step 1, collecting a plurality of point position sediments, and determining TC, OM, IC, TN and the contents of the following metals: cd. Cu, Pb, Zn, Ni, Fe, Mn;

step 2, calculating a deposit pollution index Pi according to the physicochemical property content of the deposit in the step 1_(OM)、Pi_(TP)、Pi_(TN)、FF、RI；

Step 3, respectively measuring the degradation rate D and the K value of the sample by using the catalyst of the novel water body sediment, and analyzing the degradation rate by adopting a pearson correlation matrixD. K value and the correlation of the physicochemical properties of the deposit, and selecting several factors (TC, OM, IC, TN and Pi) with better correlation_OM、Pi_TNAnd FF), and selecting the optimal regression model of each factor to model by adopting linear regression, support vector machine regression, random forest regression, gbdt regression, xgb regression and lgb regression respectively.

The invention has the beneficial effects that:

the invention provides a novel sediment recycling application which can be used as a Fenton-like catalyst to activate potassium persulfate to degrade organic matters by simply treating water polluted sediment and converting a large amount of organic matters contained in the sediment into carbon as a carbon-based catalyst (the carbon-based material has the performance of activating PSM to generate active species). The method has the advantages of wide sources, simple working procedures, lower cost and no pollution to the environment, and organic matters in the sediment are converted into carbon materials by calcining for 2 hours in the air atmosphere, so that the carbon materials are effectively utilized. Degradation experiments show that the tetracycline antibiotics in water can be efficiently removed, and the fenton-like effect is excellent. Meanwhile, the removal rate is stable under different degradation conditions. The dissolution of trace elements and macroelements is low while pollutants are efficiently degraded.

Meanwhile, through a large amount of sampling analysis, the invention discovers that the catalytic performance has positive correlation with certain pollution indexes of the sediment, on the basis, the relationship of degradation and deposition physical and chemical properties is established through mathematical modeling, the sediment is simply calcined to prepare the catalyst for a degradation experiment, and certain pollution indexes of the sediment are reversely deduced through a degradation result.

Drawings

FIGS. 1(a) -1 (f) are SEM representations of the deposit of the present invention before and after calcination;

FIG. 2 is a FTIR characterization of deposits;

FIG. 3(a) is a graph of catalyst usage;

FIG. 3(b) is a PMS usage graph;

FIG. 3(c) is an initial pH profile;

FIG. 3(d) is an inorganic anion diagram;

FIG. 4(a) shows an EPR test DMPO capture experiment;

FIG. 4(b) shows EPR test TEMP capture experiments;

FIG. 4(c) is a graph of the effect of different scavengers on tetracycline degradation;

FIG. 5 is a diagram of the reusability of the material;

FIG. 6(a) and FIG. 6(b) show the degradation rate (D) and the K value (LnC), respectively₀/C) and deposit physicochemical properties (left) and contamination level index (right);

FIG. 7 is a flow chart of the steps of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention are described below clearly and completely, and it is obvious that the described embodiments are some, not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The sediment can be used as a catalyst for activating PMS to degrade pollutants through simple three-step treatment. The method has simple steps and can realize the resource utilization of the solid waste.

Examples

As shown in fig. 7, a method for preparing a catalyst for a novel water body sediment comprises:

taking a metropolis as a background sampling area, collecting sediment samples of a certain river and lake of the metropolis, and processing sediments, wherein the processing steps are as follows:

step 1, natural air drying for 2 weeks.

And 2, picking out impurities such as tree branches and weeds, freezing and drying the collected sediment for 48 hours to obtain a pretreated sediment sample (the precursor substance in the step 3), and labeling for later use.

And 3, putting a certain amount of the sediment sample obtained in the step 2 into a 3mL crucible, then placing the crucible into a tubular furnace, heating to 700 +/-50 ℃ at a heating rate of 10 ℃/min in an air atmosphere, and calcining for 2 hours at a constant temperature to obtain the catalyst.

the catalyst prepared by the preparation method of the novel water body sediment catalyst activates PMS to generate active substances to degrade organic pollutants, and the degradation rate D and the K value of a sample are calculated.

A model for predicting total carbon and organic matter content of a deposit, comprising:

collecting 42 point samples (Li's rock, Bai tiao river, clear water river, Sanxue lake, Egret bay, Xinglong lake, Jincheng lake, Fu river, Jiangan river, peach pod village, touch river, Chongzhou culture pond and Jianyang culture pond), measuring TC, OM, IC, TN and metal content (Cd, Cu, Pb, Zn, Ni, Fe and Mn), calculating deposit pollution index Pi according to the physicochemical property content_(OM)、Pi_(TN)、Pi_(TP)、FF、RI。

Pi＝(C_sample/C_backgroud) (1)

Wherein, C_sampleMeasured concentration of sediment, C_backgroudIs a background value of sediment pollutants; c_{backgroud(TN)}＝550mg kg^-1And C_{backgroud(TP)}＝600mg kg^-1(ii) a FF represents the index of general pollution, F_aveIs the average value of TN and TP; f_maxThe maximum value of TN and TP; e_r ⁱRepresenting a potential ecological risk factor; t represents the toxicity coefficient of a single heavy metal; RI is a potential ecological risk index of a certain heavy metal, and a smaller numerical value indicates that the sediment sample has a smaller risk of heavy metal pollution.

Activating the 42 point samples by using a catalyst prepared by a novel water body sediment catalyst preparation method, respectively measuring the degradation rate D and the value K of the samples, and analyzing the degradation rate (abbreviated as D) and the value K (Ln (C)) by using a pearson correlation matrix₀The results are shown in FIGS. 6(a) -6 (b)), and factors (TC, IC, OM, TN, Zn, Pi) having a good correlation with the physicochemical properties of the deposit were selected_TN、Pi_OMFF), selecting the optimal regression model for each factor by adopting linear regression, support vector machine regression, random forest regression, gbdt regression, xgb regression and lgb regression respectively, and modeling as shown in table 1.

TABLE 1 root mean square error (Rmse) for different regression model training

Note: the smaller the Rmse, the better the data fit, and the model for each factor is the model corresponding to the smallest Rmse value.

And (3) experimental test:

experiment 1 scanning Electron microscopy (FE-SEM, Sigma HD, Zeiss, Germany) high resolution Transmission Electron microscopy (HRTEM, Tecnai G2F 20, ThermoFisher, USA).

As is clear from fig. 1(a) to 1(b), the deposit has a rough surface and many micropores, and the organic material after calcination is sintered into carbon and adheres to the surface thereof. Mapping (FIG. 1(c) -FIG. 1(f)) results showed an abundant uniform distribution of carbon.

Experiment 2 Fourier transform Infrared Spectroscopy test (FT-IR, Spectrum GX, USA)

As can be seen from FIG. 2, the surface of the deposit contained C-O, C-C, C ═ C bonds and the like at 3420cm^-1One broad peak due to-OH at the surface of the deposit.

As shown in fig. 3(a) -3 (d), experiment 3 investigated and compared the effect of different degradation parameters (catalyst amount, PMS amount, pH, inorganic anions) on degradation. Degradation experiments 10mg of MCS was added to 50ml (20mg/L) of TC solution, sonicated for 5min, and the solution was stirred with a magnetic stirrer for at least 20min to reach adsorption equilibrium. Then, 10mg of PMS was added to the above solution to initiate a reaction, samples were taken every 10min, and TC absorbance was measured in an ultraviolet-visible spectrophotometer (Cary 50, Agilent technologies, USA) and then converted into concentration for 5 times. As shown in FIGS. 4(a) to 4(c), a trace amount of the catalyst and PMS efficiently degrades TC, and the system has good catalytic performance under different initial pH and inorganic anion environments.

Experiment 4 is performed with adsorption equilibrium, then methanol MeOH, tert-butanol TBA and Acetone are used for masking free radicals, L-histidine is used for masking singlet oxygen, other experiment steps are the same as experiment 3, and EPR result analysis is combined, the results are shown in fig. 4(a) -4 (c), hydroxyl free radicals and singlet oxygen exist in the system, and the singlet oxygen is mainly generated by carbon-based activated PMS.

Experiment 5 the degradation experiment was the same as experiment 3, the degraded solution was recovered and passed through a 0.45um filter membrane, and ICP-MS was used to determine the concentration of different metal ions in the solution. The results are shown in Table 2, the dissolution of various metal ions is low, and the sediment calcination product is proved to be an environment-friendly and efficient Fenton-like catalyst.

Table 2: degradation experiment ion dissolution (mg/L)

As shown in fig. 5: after the deposit is calcined as a catalyst to participate in the reaction, the deposit is recovered in a centrifugal mode, the PMS is activated again according to the first experimental condition to degrade the tetracycline, and after five times of circulation, the degradation rate is reduced to 60%, so that the method has good reusability. The ions in the degraded solution were measured by ICP-MS, and the results are shown in Table 1. Cd. Pb, Zn, Cu, Ni, Fe and Mn ions are dissolved out low, silicon is dissolved out at 0.5667 +/-0.0008 mg/L, and silicon is used as a nonmetal element and has low influence on the environment, so the catalyst has good stability and ecological friendliness.

Experiment 6 total heavy metal: with HNO₃-HF-HClO₄Digesting at 280 ℃ by a graphite electric heating plate, measuring by using ICP-OES, and taking GBW07428(GSS-14) as a quality control; total phosphorus TP is developed by an alkali fusion-molybdenum antimony uvioresistant spectrophotometer; measuring total nitrogen TN and total carbon TC by adopting an element analyzer; and removing inorganic carbon from OC and OM by hydrochloric acid soaking method, and analyzing and determining by element analyzer.

From fig. 6(a) -6(b), the deposit physicochemical properties and the correlation of the deposit physicochemical properties with the person of activated PMS degradation were analyzed: the organic matter, the organic carbon and the total carbon have obvious positive correlation with the degradation rate, the degradation rate and the K value, the correlation coefficients are 0.73, 0.71 and 0.60 respectively, and TN has good positive correlation with the degradation rate and the K value. Of the organic contamination index of the deposit, Pi_OM、Pi_TNThere is also a positive correlation with catalytic performance. Other factors have small influence on the catalytic performance of the sediment and have weak correlation, so that an equation can be established by means of mathematical modeling and the like to reflect the organic pollution condition of the sediment through the catalytic performance.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a novel water body sediment catalyst is characterized by comprising the following steps:

step 1, collecting sediments from a river or lake, treating the sediments and naturally airing the sediments;

2. The method for preparing the novel water body sediment catalyst according to claim 1, wherein in the step 1, the catalyst is naturally air-dried for 2 weeks.

3. The application of the catalyst for the novel water body sediment is characterized by comprising the following components:

activating PMS to generate active substances by using the catalyst prepared in the claim 1, degrading organic pollutants, and calculating the degradation rate D and the K value of a sample.

4. The application of the novel catalyst for water body sediments as claimed in claim 3, is characterized in that 0.01g of the prepared catalyst is weighed in a 50mL beaker, the concentration of the catalyst is 0.2g/L, 50mL of 20ppm tetracycline TC is added, the mixture is subjected to ultrasonic treatment for 5min, magnetic stirring is carried out for adsorption and balance for 20min, then 0.01g of PMS is added, and the mixture is mixed for degrading organic matters.

5. A method of modeling total carbon and organic matter content of predicted sediment, comprising:

step 1, collecting a plurality of point position sediments, and determining the contents of TC, OM, IC, TN and Cd, Cu, Pb, Zn, Ni, Fe and Mn metals;

step 2, calculating a deposit pollution index Pi according to the physicochemical property content of the deposit in the step 1_OM、Pi_TP、Pi_TN、FF、RI；

Step 3, respectively measuring the degradation rate D and the degradation rate K of the sample by using the method as claimed in claim 3, analyzing the degradation rate D, K value by using a pearson correlation matrix, and selecting TC, OM, IC, TN and Pi_OM、Pi_TNAnd the factors of the FF are respectively subjected to linear regression, support vector machine regression, random forest regression, gbdt regression, xgb regression and lgb regression, and the optimal regression model of each factor is selected for modeling.