CN113908800B

CN113908800B - Method for removing bisphenol A in sewage by using modified red mud

Info

Publication number: CN113908800B
Application number: CN202111198291.6A
Authority: CN
Inventors: 陈志承; 余茜倩
Original assignee: China University of Geosciences
Current assignee: China University of Geosciences
Priority date: 2021-10-14
Filing date: 2021-10-14
Publication date: 2022-08-23
Anticipated expiration: 2041-10-14
Also published as: CN113908800A

Abstract

The invention relates to the technical field of wastewater treatment, in particular to a method for removing BPA in sewage by using modified red mud. A method for removing BPA in sewage by using modified red mud comprises the following steps: s1, modifying the red mud to obtain modified red mud; s2, adding the modified red mud into BPA-containing sewage, and decomposing BPA in the sewage under aeration conditions, wherein the adding amount of the modified red mud in each liter of BPA-containing sewage is 13-14 g. The invention provides a method for efficiently and stably removing BPA (bisphenol A) by using modified red mud in an alkaline environment, wherein the BPA removing effect is more than 55 percent, and the technology can be widely applied to the fields of environmental pollution treatment and environmental remediation and has good market prospect.

Description

Method for removing bisphenol A in sewage by using modified red mud

Technical Field

The invention relates to the technical field of wastewater treatment, in particular to a method for removing bisphenol A in sewage by using modified red mud.

Background

The red mud is a byproduct of extracting alumina from bauxite by using caustic soda in a Bayer process, and has the advantages of fine red mud particles, large specific surface area, strong water absorption, alkalescence and lasting alkalinity. In the last century, some countries, such as the united states, banga, japan, etc., have directly dumped red mud into the sea, causing great harm to the living and environment in the sea. In some non-coastal areas, the large accumulation of the red mud not only occupies a large amount of land area, but also can cause harm to the surrounding environment and further influence the health of human beings and organisms in the surrounding areas.

It is estimated that the worldwide alumina industry emits more than 7000 million tons of red mud per year. In 2007, the discharge amount of red mud in China reaches 4000 ten thousand tons, in 2010, the discharge amount reaches 4500-. The accumulation of the red mud causes great harm to the environment, and how to effectively utilize the red mud as resources is urgent.

With the rapid development of industrial technology, a large amount of industrial wastewater, household wastewater and farmland irrigation water have more and more serious pollutants. The pollutants are mostly pesticides, dyes, phenols, and some medical and personal care products. The treatment methods commonly used at present include adsorption treatment, chemical oxidation, electrochemical method, and the like.

The existing technologies for utilizing red mud and treating sewage are mainly based on the adsorption performance of the red mud and iron-containing minerals in the red mudThe oxidation activity of (2). The physical adsorption method is that the red mud is loaded on a porous material carrier such as activated carbon, but the method only physically adsorbs organic pollutants on the red mud and does not fundamentally realize the degradation of the pollutants (patent CN 202011142113.7); the other part of the technology is mainly based on Fenton reaction, and is prepared into a catalyst by grinding red mud, acidizing and then calcining at high temperature, but the method usually needs to use H ₂ O ₂ Chemical reagents and the like increase the cost, and meanwhile, the safety risk exists in the aspects of material transportation, storage and the like. Moreover, the pH range for effective application of the Fenton reaction is short, so that the application field of the method is severely limited. In addition, due to H ₂ O ₂ The stability is weak, the duration of the Fenton reaction on organic matters is often short, and ideal removal effect on organic pollutants in some natural environments is difficult to achieve.

At present, the technology related to air aeration is mainly based on the utilization of an air aeration method for treating sulfur-containing wastewater, removing ammonia nitrogen wastewater, arsenic-containing wastewater and the like, and the oxidation of oxygen in the air is utilized to change the form of pollutants, so that the effect of removing the pollutants is achieved, however, the technologies need to adjust the proper pH value before the wastewater is treated, and a large amount of acid and alkali can be consumed in the process, so that the application range of the technology is limited; on the other hand, some technologies based on the comprehensive use of air aeration and other methods (such as biological treatment technology, flocculation and the like) can achieve good effects on some sewage treatment, but the technical method has the disadvantages of complex treatment steps, expensive treatment cost and not wide application prospect.

Disclosure of Invention

In view of the above, the invention provides a method for removing bisphenol A in sewage by using modified red mud.

The invention provides a method for removing bisphenol A in sewage by using modified red mud, which comprises the following steps:

s1, modifying the red mud to obtain modified red mud;

s2, adding the modified red mud into the bisphenol A-containing sewage, and decomposing the bisphenol A in the sewage under aeration conditions, wherein the adding amount of the modified red mud in each liter of the bisphenol A-containing sewage is 13-14 g.

Further, the specific modification step of the red mud in the S1 comprises the following steps:

s11, carrying out freeze drying treatment on the red mud, and then sequentially carrying out grinding, sieving and ignition loss treatment;

s12, taking the burned red mud and pure water according to the mass ratio of 1: 10, mixing and stirring to prepare a red mud turbid liquid;

s13, adding a reducing agent into the red mud turbid liquid, and uniformly mixing under an oxygen-free condition to obtain modified red mud; wherein the molar concentration ratio of iron to the reducing agent in the red mud is 5: 3-30.

Further, the reducing agent in S13 is one or more of a sodium hydrosulfite mixed reagent, oxalic acid, and hydroxylamine hydrochloride.

Further, the sodium hydrosulfite mixing agent is a mixture of sodium hydrosulfite, sodium citrate and sodium bicarbonate.

Further, the air flux for aeration in S2 was 5-6L/min.

Further, the time condition for decomposition was 72 hours.

The technical scheme provided by the invention has the beneficial effects that: the invention relates to a method for removing bisphenol A in sewage by using modified red mud, which has the following advantages:

(1) the invention provides a method for efficiently and stably removing bisphenol A by using modified red mud in an alkaline environment, the removal effect of the bisphenol A reaches more than 55 percent, and the technology can be widely applied to the fields of environmental pollution treatment and environmental remediation and has good market prospect;

(2) the method has the advantages of simple reaction process, convenient operation, low requirement on equipment and low operation cost;

(3) compared with the traditional Fenton reaction technology, the method avoids the problems of use of hydrogen peroxide and a series of transportation safety and the like caused by the use of the hydrogen peroxide;

(4) the invention realizes the comprehensive utilization of the red mud waste.

Drawings

FIG. 1 is a flow chart of a method for removing bisphenol A in sewage by using modified red mud according to the invention;

FIG. 2 is an XRD representation of the raw red mud of example 1 of the present invention;

FIG. 3 is a graph showing the degradation kinetics of bisphenol A by red mud before and after modification in example 1 of the present invention;

FIG. 4 is an ESR spectrum of hydroxyl radicals of the modified red mud reaction system in example 1 of the present invention;

FIG. 5 is an ESR spectrum of hydroxyl radicals of the original red mud reaction system in example 1 of the present invention;

FIG. 6 is a graph showing the degradation kinetics of bisphenol A by three types of modified red mud in example 2 of the present invention;

FIG. 7 is a graph showing the effect of the addition amount of the modified red mud on the removal efficiency of bisphenol A in example 3 of the present invention;

FIG. 8 is a graph comparing the removal efficiency of bisphenol A by modified red mud and conventional Fenton's reagent in example 3 of the present invention.

Detailed Description

To make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be further described with reference to the accompanying drawings.

As shown in fig. 1, a method for removing bisphenol a (bpa) in sewage by using modified red mud comprises the following steps:

s1, modifying the red mud to obtain modified red mud, wherein the specific method of the red mud modification treatment comprises the following steps: s11, carrying out freeze drying treatment on the natural red mud, and then sequentially carrying out grinding, sieving and ignition loss treatment;

s13, adding a reducing agent into the red mud turbid liquid, and uniformly mixing under an oxygen-free condition to obtain modified red mud; wherein the molar concentration ratio of iron to the reducing agent in the red mud is 5: 3-30;

in the invention, the preparation method of the modified red mud is a liquid phase reduction method, the pH value of the natural red mud is 10.5, the dried red mud is ground by adopting a ceramic mortar and pestle, the ground red mud is screened by a 100-mesh nylon screen, and a powdery red mud sample is roasted in a muffle furnace at 500 ℃ for more than 12 hours for loss-on-ignition treatment. Specifically, the reducing agent is one or more of a sodium hydrosulfite-sodium citrate-sodium bicarbonate mixed reagent, oxalic acid and hydroxylamine hydrochloride. The modified red mud is alkalescent modified red mud with pH of 8.0 +/-0.5.

S2, adding the modified red mud into BPA-containing sewage, and decomposing BPA in the sewage for 78 hours under aeration conditions, wherein the adding amount of the modified red mud in each liter of BPA-containing sewage is 13-14 g. In the invention, air is pumped into the BPA-containing sewage by using an air pump, wherein the power of the air pump is 35W, the air flux of an alternating current pump of 220V is preferably 5-6L/min.

The test shows that the removal rate of BPA in the sewage by adopting the method of the invention reaches more than 55 percent. The method disclosed by the invention can have good degradation efficiency on pollutants in a slightly alkaline environment, and overcomes the limitation of pH in the conventional sewage treatment method. The invention utilizes air aeration as a 'starter' of catalytic reaction, and overcomes the dependence of the prior method technology on Fenton reagent.

The invention utilizes the use of chemical reducing agents to regulate and control the chemical form of iron in the red mud, and assists air aeration treatment to generate active species so as to degrade organic pollutants. Compared with the existing red mud-based heterogeneous Fenton reaction technology (patent CN202010521222.3), the technology avoids H ₂ O ₂ The use of the red mud can realize the high-efficiency utilization of the red mud, and can achieve ideal effect on removing organic pollutants in a slightly alkaline environment. Compared with the existing air aeration technology, the technology utilizes the high alkalinity characteristic of the red mud, does not need to regulate and control the initial pH value, has simple integral operation steps and has great application prospect in the field of wastewater treatment.

< example 1>

A method for removing BPA in sewage by using modified red mud comprises the following steps:

s11, carrying out freeze drying treatment on the natural red mud, and then sequentially carrying out grinding, sieving and ignition loss treatment;

s12, taking the weight ratio of the red mud after loss of burning to water as 1: 10, mixing and stirring to prepare a red mud turbid liquid;

s13, sequentially adding 20mL of 0.3M sodium citrate, 2.5mL of 1M sodium bicarbonate and 0.5223g of sodium hydrosulfite into 10mL of the red mud turbid solution, and uniformly mixing under an oxygen-free condition to obtain modified red mud;

s2, adding 1g of modified red mud into 72.5mL of BPA-containing sewage with the initial concentration of 6.90ug/L, introducing air into the sewage at the air flux of 5-6L/min by using an air pump, and decomposing the BPA in the sewage under the aeration condition for 78 h.

In order to compare the decomposition effect of the modified red mud prepared in this example, 72.5mL of BPA-containing wastewater with an initial concentration of 6.90ug/L was separately prepared, 1g of burned out red mud (hereinafter referred to as "virgin red mud") treated in S11 was placed in the wastewater, air was introduced into the wastewater at an air flow rate of 5-6L/min by an air pump, and the BPA in the wastewater was decomposed under aeration conditions. Wherein the pH of the original red mud is 10.5, and BET-N is used ² The specific surface area of the powder was determined by specific surface analysis, which indicated that the specific surface area was 25.1336m ² As shown in fig. 2, it can be seen from fig. 2 that the minerals contained in the original red mud mainly include hematite, quartz, calcium carbonate, and kaliophilite, which are equivalent to the mineral composition of other reported natural red mud.

At different decomposition time, 1-2mL of the sewage solution decomposed by the modified red mud and the sewage solution decomposed by the original red mud are respectively taken, filtered, and then the concentration of the BPA remained in the two sewage solutions is measured by using high performance liquid chromatography, and the test result is shown in FIG. 3. As can be seen from fig. 3, after sufficient reaction, the removal rate of BPA in sewage by the modified red mud is 54%, while the removal rate of BPA in sewage by the original red mud is only 37.5%. The hydroxyl radical ESR spectrum and the superoxide radical ESR spectrum of the modified red mud and original red mud reaction system measured at 1 hour of reaction were obtained, and the results are shown in fig. 4 and 5. As shown in fig. 4 and 5, the hydroxyl radicals and superoxide radicals generated by the modified red mud are far higher than those generated by the original red mud, and the above results show that the modified red mud has much higher efficiency for removing BPA than the natural red mud.

< example 2>

The embodiment researches the decomposition capability of the modified red mud with different reducing agent types on BPA in sewage, and comprises the following steps:

s1, preparing modified red mud of different reducing agent types:

s12, taking the mass ratio of the red mud after loss of burning to water as 1: 10, mixing and stirring to prepare a red mud turbid solution;

s13, sequentially adding 20mL of 0.3M sodium citrate, 2.5mL of 1M sodium bicarbonate and 0.5223g of sodium hydrosulfite into 10mL of the red mud turbid solution, and uniformly mixing under an oxygen-free condition to obtain sodium hydrosulfite type (DCB type) modified red mud;

s14, adding 15mL of 0.2M oxalic acid into 10mL of red mud turbid liquid, stirring, and fully reacting under an oxygen-free condition to obtain oxalic acid type (OXA type) modified red mud;

s15, adding 15mL of 0.4M hydroxylamine hydrochloride into 10mL of red mud turbid solution, stirring, and fully reacting under an oxygen-free condition to obtain hydroxylamine hydrochloride type (HAHC type) modified red mud;

s2, preparing three parts of 72.5mL of BPA sewage solution (the initial pH is 8.0 +/-1) with the initial concentration of 6.90ug/L, correspondingly adding 1g of sodium dithionite type modified red mud, 1g of oxalic acid type modified red mud and 1g of hydroxylamine hydrochloride type modified red mud into the sewage solution to obtain three reaction systems of the modified red mud with different reducing agent types, introducing air into the three reaction systems by using an air pump at the air flux of 5-6L/min, respectively taking out 1-2mL of the solution from the three reaction systems at different decomposition time, filtering the solution by using a 0.22 mu m filter membrane, and then determining the concentration of the residual BPA by using high performance liquid chromatography. As shown in fig. 6, after sufficient reaction, the removal rate of BPA from the sodium hydrosulfite-type modified red mud reaches 54%; the removal rate of the oxalic acid type modified red mud to BPA reaches 45.5 percent; the removal rate of the hydroxylamine hydrochloride type modified red mud reaches 43.4 percent. Therefore, the sodium hydrosulfite type modified red mud has the best effect of removing BPA.

< example 3>

The embodiment researches the decomposition capability of the modified red mud with different reducing agent concentrations on BPA in sewage, and comprises the following steps:

s1, carrying out freeze drying treatment on the natural red mud, and then sequentially carrying out grinding, sieving and ignition loss treatment;

s2, taking the weight ratio of the red mud after loss of burning to water as 1: 10, mixing and stirring to prepare a red mud turbid solution;

s3, preparing modified red mud with different reducing agent concentrations: s31, sequentially adding 20mL of 0.3M sodium citrate, 2.5mL of 1M sodium bicarbonate and 0.2612g of sodium hydrosulfite into 10mL of the red mud turbid solution, and uniformly mixing under an oxygen-free condition to obtain 0.2612g of sodium hydrosulfite type modified red mud (0.5xDCB type modified red mud);

s32, sequentially adding 20mL of 0.3M sodium citrate, 2.5mL of 1M sodium bicarbonate and 0.5223g of sodium hydrosulfite into 10mL of the red mud turbid solution, and uniformly mixing under an oxygen-free condition to obtain 0.5223g of sodium hydrosulfite type modified red mud (1xDCB type modified red mud);

s33, sequentially adding 20mL of 0.3M sodium citrate, 2.5mL of 1M sodium bicarbonate and 1.0446g of sodium hydrosulfite into 10mL of the red mud turbid solution, and uniformly mixing under an oxygen-free condition to obtain 1.0446g of sodium hydrosulfite type modified red mud (2xDCB type modified red mud);

s34, sequentially adding 20mL of 0.3M sodium citrate, 2.5mL of 1M sodium bicarbonate and 2.6115g of sodium hydrosulfite into 10mL of the red mud turbid solution, and uniformly mixing under an oxygen-free condition to obtain 2.6115g of sodium hydrosulfite type modified red mud (5xDCB type modified red mud);

s35, sequentially adding 20mL of 0.3M sodium citrate, 2.5mL of 1M sodium bicarbonate and 5.223g of sodium hydrosulfite into 10mL of the red mud turbid solution, and uniformly mixing under an oxygen-free condition to obtain 5.223g of sodium hydrosulfite type modified red mud (10xDCB type modified red mud);

s4, preparing five parts of BPA sewage solution (initial pH is 8.0 +/-1) with 72.5mL of initial concentration of 6.90ug/L, correspondingly adding 1g of 0.5xDCB type modified red mud, 1g of 1xDCB type modified red mud, 1g of 2xDCB type modified red mud, 1g of 5xDCB type modified red mud and 1g of 10xDCB type modified red mud (the initial pH of the reaction system is 5-9 without adjusting the pH value of the solution) to obtain a reaction system of the five parts of red mud modified by different reducing agents, introducing air into the five parts of reaction system by using an air pump at an air flux of 5-6L/min, respectively taking 1-2mL of BPA solution out of the five parts of reaction systems at different decomposition times, filtering by using a 0.22 mu m filter membrane, and measuring the concentration of the residual BPA by using high performance liquid chromatography. As shown in fig. 7, after sufficient reaction, the removal rates of BPA from the modified red mud with different concentrations of the reducing agent are all greater than 50%, wherein the removal effect of the modified red mud with 1xDCB type is the best.

< example 4>

This example explores the respective decomposition capacities of modified red mud and conventional fenton reaction (pH 8.5) for BPA in wastewater, and includes the following steps:

s2, adding 1g of modified red mud into 72.5mL of BPA-containing sewage with initial concentration of 6.90ug/L, introducing air into the sewage at an air flux of 5-6L/min by using an air pump to obtain a first reaction system, decomposing the obtained first reaction system under aeration conditions, simultaneously taking 72.5mL of BPA solution with initial concentration of 6.90ug/L, and adding 0.0025mol Fe into the BPA solution ²⁺ (ferrous ammonium sulfate) and 0.0025molH ₂ O ₂ Then, a second reaction system is obtained, and the pH of the second reaction system is adjusted to 8.25 to fully react;

s3, respectively taking 1-2mL of solution from the first reaction system and the second reaction system, filtering the solution by a 0.22 mu m filter membrane, and measuring the concentration of the residual BPA by using high performance liquid chromatography.

The test result is shown in fig. 8, and the removal rate of the modified red mud to BPA reaches 54%; the removal rate of BPA by the traditional Fenton reaction under the alkaline condition is only 28%, so that the modified red mud has better removal effect on BPA.

In this document, the terms front, back, upper, lower and the like in the drawings are used for the sake of clarity and convenience only for the components are located in the drawings and the positions of the components relative to each other. It is to be understood that the use of the directional terms should not be taken to limit the scope of the claims.

The features of the embodiments and embodiments described herein above may be combined with each other without conflict.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and should not be taken as limiting the scope of the present invention, which is intended to cover any modifications, equivalents, improvements, etc. within the spirit and scope of the present invention.

Claims

1. A method for removing bisphenol A in sewage by using modified red mud is characterized by comprising the following steps:

s1, modifying the red mud to obtain modified red mud; the specific modification steps are as follows:

s11, carrying out freeze drying treatment on the red mud, and then sequentially carrying out grinding, sieving and loss-on-ignition treatment;

s13, adding a reducing agent into the red mud turbid liquid, and uniformly mixing under an oxygen-free condition to obtain modified red mud; wherein the molar concentration ratio of iron to the reducing agent in the red mud is 5: 3-30; the reducing agent is one or more of sodium hydrosulfite mixed reagent, oxalic acid and hydroxylamine hydrochloride;

2. The method for removing bisphenol A in sewage by using modified red mud as claimed in claim 1, wherein the sodium hydrosulfite mixing reagent is a mixture of sodium hydrosulfite, sodium citrate and sodium bicarbonate.

3. The method for removing bisphenol A in sewage by using modified red mud as claimed in claim 1, wherein the air flux for aeration in S2 is 5-6L/min.

4. The method for removing bisphenol A in sewage by using modified red mud as claimed in claim 1, wherein the time condition of decomposition is 72 h.