CN113526626B - Method for removing pentavalent antimony pollutants in water by using three-dimensional iron-manganese composite electrode - Google Patents

Abstract

The invention relates to the technical field of wastewater treatment, in particular to a method for removing pentavalent antimony pollutants in water by using a three-dimensional ferro-manganese composite electrode, which comprises the following steps: iron and manganese particles are mixed to be used as an anode, and an iron plate is used as a cathode to prepare an electric flocculation reactor for treating the wastewater containing pentavalent antimony pollutants. The method for removing the pentavalent antimony pollutants in the water by using the three-dimensional iron-manganese composite electrode to strengthen the electrocoagulation effect simplifies the adding link of the medicament, reduces the treatment cost and can effectively remove the pentavalent antimony pollutants in the wastewater. Meanwhile, the content of iron and manganese in the solution after the reaction is very low, no secondary pollution is caused, and the method is very suitable for industrial popularization and application.

Description

A method for removing pentavalent antimony pollutants in water by three-dimensional iron-manganese composite electrode

technical field

The invention relates to the technical field of wastewater treatment, in particular to a method for removing pentavalent antimony pollutants in water by a three-dimensional iron-manganese composite electrode.

Background technique

In recent years, the problem of heavy metal antimony in the printing and dyeing industry has become a new challenge in pollution prevention and control. As a catalyst commonly used in the production process of raw polyester fiber (ie polyester industrial yarn) in the textile industry, antimony compounds often remain in polyester fabrics and are released in large quantities in subsequent processes. Studies have shown that antimony and its compounds have slow, acute toxicity and carcinogenicity to organisms, and have been listed as priority pollutants in various countries. At present, the commonly used methods for removing antimony pollutants in water include chemical precipitation, adsorption, ion exchange, etc. Compared with trivalent antimony, pentavalent antimony has high electronegativity and high solubility, making it more difficult to remove.

Electroflocculation technology is a hot spot in the field of water treatment research recently. Electroflocculation technology refers to the electrochemical reaction of electrodes under the action of an external electric field. The metal anode produces cations with flocculation properties, which are hydrolyzed and polymerized in solution to form a series of hydroxides or polynuclear hydroxyl complexes. Antimony pollutants are removed by adsorption, co-precipitation and air flotation. Currently, the commonly used electrode materials are iron , aluminum two, mostly plate or rod.

Some scholars have paid attention to the effect of electrode combination on the floc structure. The results show that the combined use of aluminum-iron electrodes can improve the removal efficiency, and the electroflocculation product has a better crystalline state. Some researchers added manganese sulfate or manganese chloride solution to the waste water containing antimony, and obtained a good antimony removal effect. However, additional dosing increases the difficulty of operation and increases the cost of removal.

CN 106746058 A discloses a method for removing pentavalent antimony in waste water, in which combined with the advantages of electrochemical treatment, the pentavalent antimony is now reduced to trivalent or even partially reduced to zero-valent antimony by using the working electrode, and then the coagulation The method uses ferric chloride as a flocculant to further remove antimony compounds in wastewater.

Likewise CN 104724797 A discloses a method for enhancing electrochemical removal of pentavalent antimony pollutants in water by manganese ions, utilizing a cationic dissolution method to generate ferrous and iron ions, and combining with external manganese ions to effectively reduce pentavalent antimony pollutants, and simultaneously The generation of manganese dioxide can strengthen the electroflocculation, so that the antimony pollutants in the water can be effectively removed.

However, on the one hand, the effect of such a method will be affected by the reduction degree of pentavalent antimony, and on the other hand, adding a flocculant will also increase the cost.

SUMMARY OF THE INVENTION

Aiming at the unsatisfactory effect of the prior art method for removing pentavalent antimony pollutants in wastewater, the need to add flocculants, and the high cost, the invention provides a method for removing pentavalent antimony in water by utilizing a three-dimensional iron-manganese composite electrode to enhance the effect of electric flocculation The method for pollutants, the method simplifies the adding link of medicines, reduces the treatment cost, and can effectively remove the pentavalent antimony pollutants in the wastewater.

For achieving the above object, the technical scheme adopted in the present invention is:

A method for removing pentavalent antimony pollutants in water by a three-dimensional iron-manganese composite electrode, comprising the following steps:

The iron and manganese particles are mixed as the anode, and the iron plate is used as the cathode to prepare the electroflocculation reactor to treat the wastewater containing pentavalent antimony pollutants.

The starting principle of the present invention is: the iron-manganese composite electrode prepared by using iron and manganese particles produces three-dimensional iron-manganese double hydroxide flocs with amphoteric surface hydroxyl groups under the condition of electrification, which has the advantages of large specific surface area and large adsorption capacity. , which can effectively adsorb antimony pollutants. At the same time, compared with the traditional electrode morphology, the three-dimensional porous dielectric electrode can make the electrode material have a larger contact area with the water flow and improve the yield of electroflocculation products. Increase the frequency of effective collision of flocs, increase the particle size of flocs, and enhance the effect of electro-flocculation, thereby effectively removing antimony pollutants in water. removal efficiency.

The inventor found in the research that the anode with iron and manganese particles mixed in the present invention can have a strong adsorption effect, which is convenient for the collection and removal of flocs.

The volume ratio of iron and manganese particles is 7:3 to 19:1, preferably, the volume ratio of iron and manganese particles is 7:3 to 5:1, and most preferably, when the volume ratio of iron and manganese is 8:2 , the floc has the largest specific surface area and the highest removal efficiency.

Preferably, the particle sizes of the iron and manganese particles are both 20-50 cm.

When the electro-flocculation reactor treats wastewater, the applied current is 0.20-0.35A. Less than 0.20A will result in insufficient removal, and excessive current will cause unnecessary energy loss.

When the electro-flocculation reactor treats wastewater, the hydraulic retention time is more than 30min, and less than 30min will lead to insufficient removal.

Preferably, when the electro-flocculation reactor treats waste water, the hydraulic retention time is 60-90 min. If the removal time is too long, and the electrolysis time is too long, too many metal ions will be generated, causing secondary pollution.

The distance between the anode and the cathode is 0.5-2 cm, preferably 1 cm.

When the volume of the waste water containing antimony pollutants to be treated is 2L, the volume of the anode is at least 260mL.

Compared with the prior art, the present invention has the following beneficial effects:

The method of the invention does not need to add any flocculant, the removal cost of antimony-containing pollutants is reduced, the pentavalent antimony does not need to be reduced to trivalent antimony pollutants in the treatment process, and the treatment effect is not affected by the reduction degree; The body is easy to float and has the characteristics of high-efficiency solid-liquid separation. And through the effect of the iron-manganese composite electrode, the removal efficiency of pentavalent antimony and other pollutants can be effectively improved on the one hand, and the content of iron and manganese in the solution after the reaction is also very low, and there is no harm of secondary pollution, which is very suitable for industrial application.

Description of drawings

FIG. 1 is a graph showing the variation of the removal rate of antimony pollutants with time in Example 1 and Comparative Example 1. FIG.

Fig. 2 is the SEM scanning electron microscope image of iron-manganese composite double hydroxide flocs in Example 1 and iron flocs in Comparative Example 1; wherein (a) is iron-manganese composite double hydroxide flocs; (b) is iron flocs Granular.

FIG. 3 is a graph showing the variation of the removal rate of antimony pollutants with time under different electric current densities in Example 2. FIG.

FIG. 4 is a graph showing the variation of the removal rate of antimony pollutants with time under different ratios of iron and manganese in Example 3. FIG.

FIG. 5 is a graph showing the variation of the removal rate of antimony pollutants with time under different ratios of iron and manganese in Example 4. FIG.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention. Those skilled in the art can make modifications or equivalent replacements on the basis of understanding the technical solutions of the present invention, without departing from the spirit and scope of the technical solutions of the present invention, and all should be included within the protection scope of the present invention.

Example 1

In the electrochemical reactor, the iron and manganese particles are mixed as the anode and the iron plate as the cathode. The DC power supply is used for power supply, the current density is 0.35A, the volume ratio of iron and manganese is 8:2, the volume ratio of anode volume to water to be treated is 260ml/2L, and the distance between the plates is 1cm. Prepare antimony-containing wastewater, wherein the pentavalent antimony concentration is 1mg/L, adjust the pH value of the water to 6.5, pump the water to be treated into the electrochemical reactor, turn on the power supply, and start the reaction. When the treatment time is 60 minutes, the antimony removal rate reaches 95.19%, and when the treatment time is 90 minutes, the antimony removal rate reaches 98.74%.

Comparative Example 1

A three-dimensional iron electrode was prepared by using iron particles, which was used as an anode to replace the iron-manganese composite electrode in Example 1. Other conditions were the same as in Example 1, and the treatment effect of pentavalent antimony pollutants in wastewater was tested. When the treatment time is 60 minutes, the antimony removal rate reaches 81.8%, and when the treatment time is 90 minutes, the antimony removal rate reaches 94.45%.

Figure 1 shows a comparison of the removal effects of Example 1 and Comparative Example 1 on antimony pollutants.

The iron-manganese composite double hydroxide flocs prepared in Example 1 and the iron flocs prepared in Comparative Example 1 were observed microscopically. The SEM scanning results are shown in Figure 2, where (a) is the iron-manganese composite double hydroxide. The floc has a hexagonal sheet-like structure with a larger specific surface area and more surface active adsorption points; while the iron floc in (b) is granular, has a precise accumulation and a small specific surface area, which is also the reason for the two The main reason for the difference in the removal of antimony contaminants. During the experiment, it was found that when the reaction time was the same, the iron-manganese electrode was used, and it was observed that the solution in the reactor was relatively clear, and the scum layer on the surface was obviously thicker, indicating that the air flotation effect was good and the separation ability was strong.

Example 2

In the electrochemical reactor, the iron and manganese particles are mixed as the anode and the iron plate as the cathode. The DC power supply was used for power supply. Four control groups were set up in the experiment. The current densities were 0.20A, 0.25A, 0.30A and 0.35A respectively. Prepare antimony-containing wastewater, wherein the pentavalent antimony concentration is 1mg/L, adjust the pH value of the water to 6.5, pump the water to be treated into the electrochemical reactor, turn on the power supply, and start the reaction. The results are shown in Figure 3. When the treatment time is 60 minutes, the antimony removal rate is the lowest at 0.20A, which is 76.24%, and the antimony removal rate is the highest at 0.35A, which is 95.19%. When the treatment time is 90 minutes, the current The antimony removal rate was the lowest under the density of 0.20A, which was 80.98%, and the antimony removal rate was the highest under the current density of 0.35A, which was 98.74%. It can be seen that the removal efficiency of antimony pollutants will be lower if the current density is too small, but the removal effect of antimony pollutants will also be unsatisfactory if the current density is too large.

Example 3

In the electrochemical reactor, the iron and manganese particles are mixed as the anode and the iron plate as the cathode. DC power supply was used for power supply. Four control groups were set up in the experiment. The volume ratios of iron and manganese were 7:3; 8:2; 9:1; 19:1; the volume ratio of anode to water to be treated was 260ml/2L; is 0.35A, and the distance between the plates is 1cm. The antimony-containing wastewater was prepared, wherein the pentavalent antimony concentration was 1 mg/L, the pH value of the water was adjusted to 6.5, the water to be treated was pumped into the electrochemical reactor, the power was turned on, and the reaction was started. The results are shown in Figure 4. When the treatment time is 60 minutes, when the volume ratio of iron and manganese is 7:3, the antimony removal rate is the lowest, which is 90.03%, and when the volume ratio of iron and manganese is 8:2, the removal rate of antimony is the highest, which is 95.19 %, when the treatment time is 90 minutes, the antimony removal rate is the lowest when the iron-manganese volume ratio is 19:1, which is 96.76%, and the antimony removal rate is the highest when the iron-manganese volume ratio is 8:2, which is 98.74%. On the whole, when the iron content gradually increases, the removal efficiency of antimony pollutants first increases and then decreases. Therefore, the best antimony pollutant treatment effect can be obtained by controlling the ratio of the two in the optimal range.

Example 4

In order to verify that the adsorption effect of iron and manganese flocs is stronger than that of iron flocs, under different ratios of iron and manganese in Example 3, after the reaction, the flocs were collected by centrifugation, and a re-adsorption experiment was carried out. Add 1 g of flocs to 100 ml of wastewater with an initial concentration of Sb(V) of 1 mg/L and pH=6.5, and stir with a magnetic stirrer with a rotating speed of 500 r/min to make the flocs evenly dispersed in the beaker, and the removal rate increases with time. The changes are shown in Figure 5. It can be clearly seen that the mixed system of iron and manganese, in which the efficiency of antimony pollutants is much higher than that of iron system. The body removal rate is only 20.87%.

Table 1 Removal rate of antimony pollutants under different ratios of iron and manganese

Claims (4)

1. a three-dimensional iron-manganese composite electrode removes the method for pentavalent antimony pollutants in water, is characterized in that, comprises the steps: iron, manganese particles are mixed as anode, iron plate are prepared as negative electrode electroflocculation reactor, process containing pentavalent antimony Wastewater from antimony contaminants; The volume ratio of iron and manganese is 7:3 to 19:1; When the electro-flocculation reactor treats wastewater, the applied current is 0.20-0.35A; When the electro-flocculation reactor treats wastewater, the hydraulic retention time is 60-90 minutes. 2 . The method for removing pentavalent antimony pollutants in water by a three-dimensional iron-manganese composite electrode according to claim 1 , wherein the volume ratio of iron and manganese is 7:3 to 5:1. 3 . 3 . The method for removing pentavalent antimony pollutants in water by a three-dimensional iron-manganese composite electrode according to claim 1 , wherein the particle diameters of iron and manganese particles are both 20-50 cm. 4 . 4 . The method for removing pentavalent antimony pollutants in water with a three-dimensional iron-manganese composite electrode according to claim 1 , wherein the distance between the anode and the cathode is 0.5-2 cm. 5 .

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