Method for removing heavy metal ions from wastewater by adsorption, and method for regenerating adsorbent material

Abstract

The present invention provides a method for removing heavy metal ions from wastewater by adsorption, and a method for regenerating an adsorbent material. The method for removing heavy metal ions from wastewater of the present invention adjusts the pH values ​​of wastewater in the first pH regulating tank, the second pH regulating tank, and the third pH regulating tank respectively to meet the optimal treatment pH range of different heavy metal ions, thereby realizing selective adsorption and removal of heavy metal ions such as antimony, arsenic, lead, and chromium in different adsorption columns, and has strong applicability to wastewater with complex pollution containing heavy metal ions such as Sb, As, Cd, and Pb; the method for regenerating an adsorbent material of the present invention can regenerate it using a sodium hydroxide solution or a hydrochloric acid solution, and at the same time, the adsorption regeneration liquid contains high concentrations of heavy metal ions such as Sb, As, Cd, and Pb, which can lay a foundation for the recycling of these heavy metal ions.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment, and in particular to a method for removing heavy metal ions from wastewater by adsorption and a method for regenerating an adsorption material. Background Art

[0002] Antimony and its compounds are important industrial raw materials, widely used in the production of flame retardants, alloys, semiconductors, etc., resulting in the increasing concentration of heavy metals such as antimony in the water and soil environment. However, antimony is also a potentially toxic and carcinogenic heavy metal, and is listed as one of the high-priority pollutants by countries and organizations such as the World Health Organization (WHO), the United States, Japan and China. As a major producer and exporter of antimony, my country has also included antimony in the strict restriction range. my country's antimony ore resources are mainly distributed in provinces such as Hunan, Guangxi, and Guizhou, such as the Lengshuijiang Tin Mine, Zhazixi and Banxi antimony mining areas in Hunan; metal antimony ores are often associated with sulfide minerals such as As, Cd, Pb, and Fe. In the long-term high-intensity mining activities, these sulfide minerals will undergo physical and chemical and biochemical reactions under the combined action of mechanical crushing, rainfall leaching, and microorganisms, producing a large amount of acidic mine wastewater. Acidic mine wastewater often contains a large amount of heavy metal ions such as Sb, As, Cd, and Pb. At present, the formation mechanism of acid mine drainage from antimony sulfide mines is unclear, and the pollution prevention and control technology is insufficient, which leads to the continuous increase of the concentration of heavy metal ions such as antimony in the water and soil environment of antimony mining areas, causing great harm to the health of residents in mining areas and having a serious impact on social development and stability. Therefore, how to remove heavy metal ions such as Sb, As, Cd, and Pb from acid mine drainage has become an urgent problem to be solved. Summary of the invention

[0003] In view of this, the present invention proposes a method for removing heavy metal ions from wastewater by adsorption and a method for regenerating adsorbent materials, so as to solve or at least partially solve the technical problems existing in the prior art.

[0004] In a first aspect, the present invention provides a method for removing heavy metal ions from wastewater by adsorption, comprising the following steps:

[0005] Passing the wastewater into the first pH adjustment tank and adjusting the pH of the wastewater to 2-4;

[0006] The wastewater in the first pH adjustment tank is introduced into a first treatment tank, wherein a plurality of antimony arsenic ion adsorption columns are provided in the first treatment tank, and the wastewater flows through the antimony arsenic ion adsorption columns and is adsorbed;

[0007] The wastewater in the first treatment tank is introduced into the second pH adjustment tank, and the pH of the wastewater is adjusted to 4-6;

[0008] The wastewater in the second pH adjustment tank is introduced into a second treatment tank, wherein a plurality of lead ion adsorption columns are provided in the second treatment tank, and the wastewater flows through the lead ion adsorption columns and is adsorbed;

[0009] The wastewater in the second treatment tank is introduced into the third pH adjustment tank, and the pH of the wastewater is adjusted to 6-9;

[0010] The wastewater in the third pH adjustment tank is introduced into a third treatment tank, wherein a plurality of cadmium ion adsorption columns are provided in the third treatment tank, and the wastewater flows through the cadmium ion adsorption columns and is adsorbed;

[0011] The adsorption materials used in the antimony arsenic ion adsorption column, the lead ion adsorption column, and the cadmium ion adsorption column are all Fe 3 O 4 -HCO composite adsorbent.

[0012] Preferably, in the method for removing heavy metal ions from wastewater by adsorption, the Fe 3 O 4 The preparation method of the -HCO composite adsorbent comprises the following steps:

[0013] 100 parts by weight of the ground sludge raw material is taken, dried at 100 to 500° C. for 2 to 8 hours, crushed and ground to obtain powder particles A with a particle size of 80 to 200 meshes, which are set aside;

[0014] With FeSO 4 and pure water as raw materials, prepare solution B with a mass ratio of 1:5 to 1:10; then add FeCl 3 and pure water as raw materials, prepare solution C with a mass ratio of 1:3 to 1:5; wherein: Fe 2+ and Fe 3+ The molar ratio is 1:1 to 1:3, and it is reserved;

[0015] Use pure water to dilute the concentrated ammonia water to prepare 500 parts by volume of an ammonia solution D with a concentration of 5% to 15 vol%, for standby use; wherein the volume of the ammonia water and the mass of the grinding sludge are based on ml:g;

[0016] Under the condition of heating temperature of 50-100° C., nitrogen is passed through the reactor for 5-10 minutes, and then powder particles A, solution B, solution C and solution D are respectively added into the reactor in proportion, stirred and mixed to be uniformly prepared into solution E, and then the temperature is kept constant, and the stirring reaction is continued at a speed of 150-500 rpm for 1-5 hours. Nitrogen protection needs to be continuously passed through during the stirring process. The product is separated by a magnet, washed with deionized water and anhydrous ethanol, and then dried at 50-100° C. for 8-24 hours. Finally, the dried solid is ground at room temperature to obtain powder particles of 80-200 mesh, which is Fe 3 O 4 -HCO composite adsorbent; the sludge contains rare earth oxides of lanthanum and cerium, SiO 2 and Al 2 O 3 .

[0017] Preferably, in the method for removing heavy metal ions from wastewater by adsorption, the molar ratio of Ce element to Fe element in the adsorbent used in the antimony arsenic ion adsorption column is 1:1; the molar ratio of Ce element to Fe element in the adsorbent used in the lead ion adsorption column and the cadmium ion adsorption column is 1.5:1.

[0018] Preferably, in the method for removing heavy metal ions from wastewater by adsorption, the wastewater flows through an antimony arsenic ion adsorption column and is maintained for 4 to 10 hours; the wastewater flows through a lead ion adsorption column and is maintained for 4 to 10 hours; the wastewater flows through a cadmium ion adsorption column and is maintained for 4 to 10 hours.

[0019] Preferably, in the method for removing heavy metal ions from wastewater by adsorption, the pH of the wastewater is adjusted to 2-4 or 4-6 using hydrochloric acid or sulfuric acid.

[0020] Preferably, the method for removing heavy metal ions from wastewater by adsorption comprises adjusting the pH of the wastewater to 6-9 using hydrochloric acid or sulfuric acid and sodium hydroxide or calcium oxide.

[0021] In the second aspect, the present invention also provides a method for regenerating the adsorbent material used in the method for removing heavy metal ions from wastewater by adsorption, comprising the following steps: passing the regeneration liquid into the first treatment tank, the second treatment tank, and the third treatment tank respectively, allowing the regeneration liquid to flow through the antimony arsenic ion adsorption column, the lead ion adsorption column, and the cadmium ion adsorption column and cleaning the adsorption column; wherein the regeneration liquid is a sodium hydroxide solution or a hydrochloric acid solution.

[0022] Preferably, the regeneration method of the adsorption material, after cleaning the adsorption column with the regeneration liquid, also includes: passing water into the first treatment tank, the second treatment tank, and the third treatment tank respectively, so that the water flows through the antimony arsenic ion adsorption column, the lead ion adsorption column, and the cadmium ion adsorption column and cleans the adsorption column.

[0023] Preferably, in the regeneration method of the adsorbent material, the concentration of the sodium hydroxide solution is 0.1-1.0 mol / L, and the concentration of the hydrochloric acid solution is 0.1-1.0 mol / L.

[0024] The method for removing heavy metal ions from wastewater by adsorption and the method for regenerating adsorbent materials of the present invention have the following beneficial effects compared with the prior art:

[0025] 1. The method for removing heavy metal ions from wastewater by adsorption of the present invention adjusts the pH value of the heavy metal wastewater in the first pH adjustment tank, the second pH adjustment tank and the third pH adjustment tank respectively to meet the optimal treatment pH range of different heavy metal ions, thereby realizing efficient selective adsorption and removal of heavy metal ions such as antimony, arsenic, lead and chromium in different adsorption columns, and has strong applicability and application to composite wastewater containing heavy metal ions such as Sb, As, Cd and Pb;

[0026] 2. The regeneration method of the adsorbent material of the present invention can utilize sodium hydroxide solution or hydrochloric acid solution to regenerate it. Meanwhile, the adsorption regeneration liquid contains high concentrations of Sb and As ions, Cd ions, and Pb ions, respectively, which can lay a foundation for the recycling of these heavy metal ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 The schematic diagram of the device structure used in the method for removing heavy metal ions from wastewater by adsorption of the present invention;

[0029] Figure 2 Fe at different pH 3 O 4 -HCO composite adsorbent for Sb ion removal rate and adsorption capacity;

[0030] Figure 3 Fe at different pH 3 O 4 -HCO composite adsorbent for As ion removal rate and adsorption capacity;

[0031] Figure 4 Fe at different pH 3 O 4 -HCO composite adsorbent for Pb ion removal rate and adsorption capacity;

[0032] Figure 5 Fe at different pH 3 O 4 -HCO composite adsorbent for Cd ion removal rate and adsorption capacity;

[0033] Figure 6 Fe 3 O 4 -XRD pattern of HCO composite adsorbent after adsorption of As and Sb ions;

[0034] Figure 7 Fe 3 O 4 -XRD spectrum of HCO composite adsorbent after adsorption of Pb and Cd ions;

[0035] Figure 8 Fe 3 O 4 -XRD patterns of HCO composite adsorbent before and after adsorption;

[0036] Fig. 9 Fe 3 O 4 -XPS spectrum of HCO composite adsorbent after adsorption of As(V);

[0037] Fig.10 Fe 3 O 4 -XPS spectrum of HCO composite adsorbent after adsorption of Sb(V);

[0038] Fig.11 Fe 3 O 4 -XPS spectrum of HCO composite adsorbent after adsorption of Pb(Ⅱ);

[0039] Fig.12 Fe 3 O 4 XPS spectrum of Cd(Ⅱ) adsorbed on -HCO composite adsorbent. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different proportions.

[0041] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0043] In the description of the present invention, it should be understood that the directions or positions indicated by “upper” and the like are based on the directions or positions shown in the accompanying drawings, or are the directions or positions in which the product of the invention is usually placed when in use, or are directions or positions commonly understood by those skilled in the art. These directions or positions are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0044] Furthermore, the terms “first”, “second”, etc. are merely used for distinguishing descriptions and are not to be understood as indicating or implying relative importance.

[0045] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] The present invention provides a method for removing heavy metal ions from wastewater by adsorption, comprising the following steps:

[0047] S1, passing the wastewater into the first pH adjustment tank, and adjusting the pH of the wastewater to 2-4;

[0048] S2, introducing the wastewater in the first pH adjustment tank into a first treatment tank, wherein a plurality of antimony arsenic ion adsorption columns are provided in the first treatment tank, and the wastewater flows through the antimony arsenic ion adsorption columns and is adsorbed;

[0049] S3, introducing the wastewater in the first treatment tank into the second pH adjustment tank, and adjusting the pH of the wastewater to 4-6;

[0050] S4, introducing the wastewater in the second pH adjustment tank into a second treatment tank, wherein a plurality of lead ion adsorption columns are provided in the second treatment tank, and the wastewater flows through the lead ion adsorption columns and is adsorbed;

[0051] S5, introducing the wastewater in the second treatment tank into the third pH adjustment tank, and adjusting the pH of the wastewater to 6-9;

[0052] S6, introducing the wastewater in the third pH adjustment tank into a third treatment tank, wherein the third treatment tank is provided with a plurality of cadmium ion adsorption columns, and the wastewater flows through the cadmium ion adsorption columns and is adsorbed;

[0053] Among them, the adsorption materials used in the antimony arsenic ion adsorption column, the lead ion adsorption column, and the cadmium ion adsorption column are all Fe 3 O 4 -HCO composite adsorbent, but Fe 3 O 4 The molar ratio of Ce and Fe in the -HCO composite adsorbent should be optimized according to the heavy metal ions to be adsorbed and removed.

[0054] It should be noted that the method for adsorbing and removing heavy metal ions in wastewater of the present application, the antimony and arsenic ion adsorption column, the lead ion adsorption column, and the cadmium ion adsorption column all include a shell and an adsorption material filled in the shell. Obviously, a plurality of through holes are opened on the outer periphery of the shell to facilitate the contact between the wastewater and the adsorption material filled in the shell for adsorption.

[0055] Further references Figure 1As shown, the device used in the method for removing heavy metal ions from wastewater of the present application is shown in the figure. The device includes a first pH regulating tank 1, on which a water inlet pipe 11 is opened; a first treatment tank 2, in which a plurality of antimony and arsenic ion adsorption columns 3 are arranged; a first pipe 21, one end of which is connected to the first pH regulating tank 1 and the other end is connected to the first treatment tank 2; a second pH regulating tank 4, between which a second pipe 41 is arranged, and the first treatment tank 2, and the second pipe 41 is connected to the first treatment tank 2 at one end, and the second pH regulating tank 4 at the other end; a second treatment tank 5, in which a plurality of lead ion adsorption columns 6 are arranged; a third pipe 51, one end of which is connected to the second pH regulating tank 4 and the second end is connected to the second treatment tank 5; a third pH regulating tank 9, between which a fourth pipe 91 is arranged, and the fourth pipe 91 is connected to the second treatment tank 5 at one end, and the third pH regulating tank 9 at the other end; The third treatment tank 92 is provided with a plurality of cadmium ion adsorption columns 93; the fifth pipeline 94 is connected to the third pH regulating tank 9 at one end and to the third treatment tank 92 at the other end, and the third treatment tank 92 is also provided with a clean water drainage pipe 90; the recovery tank 95, the water after adsorption treatment between the recovery tank 95 and the clean water drainage pipe 90 flows into the recovery tank 95 through the clean water drainage pipe 90 for storage; the alkali liquid storage tank 7, which stores alkali liquid such as sodium hydroxide solution, potassium hydroxide solution or calcium oxide solution; the acid storage tank 8, which stores acid such as hydrochloric acid or sulfuric acid; the sixth pipeline 71 is connected to the alkali liquid storage tank 7 and the acid storage tank 8 through the seventh pipeline 72 respectively; the sixth pipeline 71 is connected to the first pH regulating tank 1, the second pH regulating tank 4 and the third pH regulating tank 9 through the eighth pipeline 73 respectively. The first pH regulating tank 1, the second pH regulating tank 4 and the third regulating tank 9 are all provided with a stirring mechanism 12. The stirring mechanism 12 is a conventional stirring device for stirring the wastewater in the regulating tank. Valves 22 are provided on the first pipeline 21 , the second pipeline 41 , the third pipeline 51 , the fourth pipeline 91 , the fifth pipeline 94 , the sixth pipeline 71 , the seventh pipeline 72 and the eighth pipeline 73 , and correspondingly, water pumps may be provided on the pipelines according to the circumstances.

[0056] The principle of using the above device for wastewater treatment is:

[0057] The wastewater is introduced into the first pH regulating tank 11 through the water inlet pipe 11, and the pH is adjusted to 2-4 by the acid in the acid storage tank 8; the wastewater after pH adjustment is introduced into the first treatment tank 2 through the first pipe 21, and the wastewater flows through the antimony arsenic ion adsorption column 3 and is adsorbed in the adsorption column; the wastewater is then introduced into the second pH regulating tank 4 through the second pipe 41, and the pH is adjusted to 4-6 by the acid in the acid storage tank 8; the wastewater is then introduced into the second treatment tank 5 through the third pipe 51, and the wastewater flows through the lead ion adsorption column 6 and is adsorbed; the wastewater is then introduced into the third pH regulating tank 9 through the fourth pipe 91, and then the pH of the wastewater is adjusted to 6-9 by the acid in the acid storage tank 8 or the alkali in the alkali storage tank 7; the wastewater is then introduced into the third treatment tank 92 through the fifth pipe 94, and the wastewater flows through the cadmium ion adsorption column 93 and is adsorbed; the water after adsorption finally flows into the recovery tank 95 through the drain pipe 90 for storage.

[0058] The adsorption materials used in the antimony arsenic ion adsorption column, lead ion adsorption column and cadmium ion adsorption column of the present application are Fe 3 O 4 -HCO composite adsorbent, the Fe 3 O 4 The specific preparation method of -HCO composite adsorbent refers to the patent application number 201811433418.6. The wastewater in this application is antimony mining and beneficiation wastewater, and the heavy metal ions contained in it mainly include Sb, As, Cd, and Pb, which mainly exist in the valence states of Sb(V), As(V), Pb(II), and Cd(II). The Fe used in this application 3 O 4 -HCO composite adsorbent has different pH applicable ranges for different heavy metal ions.

[0059] Specifically, in the wastewater containing only Sb(V), the pH of the wastewater was adjusted to between 2 and 9, and an antimony arsenic ion adsorption column was used, and the adsorption material used in the adsorption column was Fe 3 O 4 -HCO composite adsorbent; testing Fe at different pH 3 O 4 -HCO composite adsorbent for Sb ion removal rate and adsorption capacity, the results are as follows Figure 2 shown.

[0060] According to the same method as above, Fe 3 O 4 -HCO composite adsorbent for As ion removal rate and adsorption capacity, the results are as follows Figure 3 shown.

[0061] According to the same method as above, Fe3 O 4 -HCO composite adsorbent for Pb ion removal rate and adsorption capacity, the results are as follows Figure 4 shown.

[0062] According to the same method as above, Fe 3 O 4 -HCO composite adsorbent for Cd ion removal rate and adsorption capacity, the results are as follows Figure 5 shown.

[0063] From above Figures 2 to 5 It can be seen that Fe 3 O 4 The optimal pH values ​​for the adsorption and removal of Sb(V), As(V), Pb(II), and Cd(II) by -HCO composite adsorbent are 2-4, 2-6, 4-6, and 6-9, respectively. 3 O 4 -HCO composite adsorbent has different optimal pH for adsorption and removal of Sb(V), As(V), Pb(II), and Cd(II). Therefore, considering the characteristics of antimony mining and beneficiation wastewater, which is acidic mine wastewater and has a low pH, the present invention achieves the selective removal of heavy metal ions such as Sb(V), As(V), Pb(II), and Cd(II) by controlling and adjusting the pH of antimony mining and beneficiation wastewater, that is, Sb(V) and As(V) are first adsorbed and removed at a pH of 2-4, Pb(II) ions are adsorbed and removed at a pH of 4-6, and Cd(II) is adsorbed and removed at a pH of 6-9. Under acidic conditions, Fe 3 O 4 The priority order of adsorption of heavy metal ions by -HCO composite adsorbent is: As(V)>Sb(V)>Pb(Ⅱ)>Cd(Ⅱ); under alkaline conditions, Fe 3 O 4 The priority order of adsorption of heavy metal ions by -HCO composite adsorbent is: Pb(Ⅱ)>As(Ⅴ)>Cd(Ⅱ)>Sb(Ⅴ).

[0064] This application is based on Fe 3 O 4 -HCO adsorption mechanism analysis of the adsorption column with composite adsorbent.

[0065] Test Fe 3 O 4 -HCO composite adsorbent and the X-ray diffraction (XRD) patterns of the remaining precipitates after adsorption of Sb(V), As(V), Pb(II), and Cd(II). The results are as follows Figures 6 to 8 shown. Figure 8 Fe 3 O 4-HCO composite adsorbent means that it has not been adsorbed, that is, Fe before adsorption 3 O 4 XRD pattern of -HCO composite adsorbent.

[0066] Test Fe 3 O 4 The XPS spectra of the -HCO composite adsorbent and the remaining precipitate after adsorption of Sb(V), As(V), Pb(II), and Cd(II) are as follows: Figures 9 to 12 shown.

[0067] The above X-ray diffraction (XRD) and XPS spectra show that the adsorption process is mainly Fe and Ce oxides (Ce 2 O 3 、CeO 2 、FeOOH、Fe 3 O 4 , Fe 2 O 3 、FeCe 2 O 4 ) surface groups and heavy metal ions such as Sb(V), As(V), Pb(II), and Cd(II) undergo ligand exchange and complexation, and heavy metals may also react with OH in the solution. - Precipitation is generated, and some protonated functional groups on the surface of the adsorbent are positively charged and interact electrostatically with pollutants.

[0068] Fe 3 O 4 Ce in the -HCO composite adsorbent is mainly CeO 2 and Ce 2 O 3 After adsorbing heavy metals As(V), Sb(V), Pb(II), and Cd(II), the peak binding energy of Ce(III) migrates. Therefore, it is inferred that the cerium oxide in the adsorbent reacts with the heavy metal ions to form a complex Ce-OY (Formula (1)) related to Ce and heavy metals, thereby transferring and removing the heavy metals in the solution.

[0069] Ce 2 O 3 +Y+H + →Ce-O-Y+H 2 O (1)

[0070] Among them, X is the carrier HCO, Y represents the heavy metal, and Z is the anion coordinated by the adsorption center, such as OH - .

[0071] Adsorption and removal mechanism of As(V). The optimal pH value for As(V) removal is 2-6, and the solution is in a slightly acidic state. At this time, As(V) is mainly in the form of H 2 AsO 4 - Existing in the solution, XRD characterization analysis shows that As(V) will react with FeOOH and Ce on the adsorbent 2 O 3 A complexation reaction occurs to generate Fe-O-As and Ce-O-As compounds (Formulas (2) and (3)), and a ligand exchange reaction occurs with X≡Fe-OH to generate an X≡Fe-As compound (Formula (4)).

[0072] FeOOH+H 2 AsO 4 - +H + →FeAsO 4 (2)

[0073] Ce 2 O 3 +H 2 AsO 4 - →CeAsO 4 +H 2 O (3)

[0074] X≡Fe-OH+H 2 AsO 4 - →Fe-OH 2 AsO 4 +H 2 O (4)

[0075] Adsorption and removal mechanism of Sb(V). Sb(V) is removed by Sb(OH) under the optimal reaction conditions (pH = 2). 6 - exists in the form of FeOOH and Ce 2 O 3 A complexation reaction occurs to generate Fe-O-Sb and Ce-O-Sb compounds (Formulas (5) and (6)), and a ligand exchange reaction occurs with X≡Fe-OH to generate a X≡Fe-Sb compound (Formula (7)).

[0076] H + +FeOOH+Sb(OH) 6 - →FeSbO 4 (5)

[0077] H + +Ce 2 O 3+Sb(OH) 6 - →CeSbO 4 +H 2 O (6)

[0078] X≡Fe-OH+Sb(OH) 6 - →Fe-O-Sb(OH) 5 - +H 2 O (7)

[0079] The adsorption and removal mechanism of Pb(Ⅱ). During the adsorption process, lead is mainly in the form of Pb 2+ The XRD characterization analysis shows that Pb(Ⅱ) and Fe 3 O 4 The iron cerium oxide in the -HCO composite adsorbent undergoes ligand exchange and complexation reaction to generate compounds (Formulas (8) and (9)). In addition, Pb(II) can also react with OH in water. - A reaction occurs to generate a precipitate (Formula (10)).

[0080] H + +FeOOH+Pb 2+ →PbFe 2 O 4 +H 2 O (8)

[0081] Ce 2 O 3 +Pb 2+ →Ce 2 Pb 2 O 6 (9)

[0082] Pb 2+ +OH - →Pb(OH) 2 (10)

[0083] Adsorption and removal mechanism of Cd(Ⅱ). During the adsorption process, cadmium is mainly in the form of Cd 2+ The XRD characterization analysis shows that Cd(Ⅱ) and Fe 3 O 4 The iron oxide in the -HCO composite adsorbent undergoes a ligand exchange reaction to remove it (Formula (11)), but no Cd and Ce compounds were found in the characterization results, indicating that no complex reaction occurred. Cd(II) can also react with OH in water. - A reaction occurs to generate a precipitate (Formula (12)).

[0084] H + +FeOOH+Cd 2+ →CdFe 2 O 4 +H 2 O (11)

[0085] Cd 2+ +OH - →Cd(OH) 2 (12)

[0086] In some embodiments, Fe is prepared according to patent application number 201811433418.6. 3 O 4 -HCO composite adsorbent, specifically, Fe 3 O 4 The preparation method of the -HCO composite adsorbent comprises the following steps:

[0087] 100 parts by weight of the ground sludge raw material is taken, dried at 100 to 500° C. for 2 to 8 hours, crushed and ground to obtain powder particles A with a particle size of 80 to 200 meshes, which are set aside;

[0088] With FeSO 4 and pure water as raw materials, prepare solution B with a mass ratio of 1:5 to 1:10; then add FeCl 3 and pure water as raw materials, prepare solution C with a mass ratio of 1:3 to 1:5; wherein: Fe 2+ and Fe 3+ The molar ratio is 1:1-1:3, for standby use;

[0089] Use pure water to dilute the concentrated ammonia water to prepare 500 parts by volume of an ammonia solution D with a concentration of 5% to 15 vol%, for standby use; wherein the volume of the ammonia water and the mass of the grinding sludge are based on ml:g;

[0090] Under the condition of heating temperature of 50-100° C., nitrogen is passed through the reactor for 5-10 minutes, and then powder particles A, solution B, solution C and solution D are respectively added into the reactor in proportion, stirred and mixed to be uniformly prepared into solution E, and then the temperature is kept constant, and the stirring reaction is continued at a speed of 150-500 rpm for 1-5 hours. Nitrogen protection needs to be continuously passed through during the stirring process. The product is separated by a magnet, washed with deionized water and anhydrous ethanol, and then dried at 50-100° C. for 8-24 hours. Finally, the dried solid is ground at room temperature to obtain powder particles of 80-200 mesh, which is Fe 3 O 4 -HCO composite adsorbent; sludge contains rare earth oxides of lanthanum and cerium, SiO 2and Al 2 O 3 .

[0091] In some embodiments, the molar ratio of Ce element to Fe element in the adsorbent used in the antimony arsenic ion adsorption column is 1:1; the molar ratio of Ce element to Fe element in the adsorbent used in the lead ion adsorption column and the cadmium ion adsorption column is 1.5:1.

[0092] In some embodiments, the wastewater flows through an antimony arsenic ion adsorption column and remains for 4 to 10 hours; the wastewater flows through a lead ion adsorption column and remains for 4 to 10 hours; the wastewater flows through a cadmium ion adsorption column and remains for 4 to 10 hours.

[0093] The above-mentioned 4-10h maintenance means that the Fe 3 O 4 The time taken for the -HCO composite adsorbent to contact and adsorb the wastewater is to allow the heavy metal ions in the wastewater to be fully adsorbed by the adsorbent. Specifically, the Fe in the adsorption column can be controlled by controlling the valve. 3 O 4 -HCO adsorption time of composite adsorbent and wastewater.

[0094] In some embodiments, the pH of the wastewater is adjusted to 2-4 or 4-6 using hydrochloric acid or sulfuric acid.

[0095] In some embodiments, the pH of the wastewater is adjusted to 6-9 using hydrochloric acid or sulfuric acid and sodium hydroxide or calcium oxide.

[0096] Based on the same inventive concept, the embodiment of the present application also provides a method for regenerating the adsorbent material used in the above-mentioned method for removing heavy metal ions from wastewater by adsorption, comprising the following steps:

[0097] The regeneration liquid is respectively introduced into the first treatment tank, the second treatment tank, and the third treatment tank, so that the regeneration liquid flows through the antimony arsenic ion adsorption column, the lead ion adsorption column, and the cadmium ion adsorption column and cleans the adsorption column; wherein the regeneration liquid is a sodium hydroxide solution or a hydrochloric acid solution.

[0098] In some embodiments, after cleaning the adsorption column with the regeneration liquid, it also includes: passing water into the first treatment tank, the second treatment tank, and the third treatment tank respectively, so that the water flows through the antimony arsenic ion adsorption column, the lead ion adsorption column, and the cadmium ion adsorption column and cleans the adsorption column.

[0099] In some embodiments, the concentration of the sodium hydroxide solution is 0.1-1.0 mol / L, and the concentration of the hydrochloric acid solution is 0.1-1.0 mol / L.

[0100] Specifically, the regeneration method of the adsorbent material can also be adopted Figure 1The device is performed by the device shown in . The device also includes a regeneration liquid storage tank 10, which is connected to the lower ends of the first treatment tank 2, the second treatment tank 5, and the third treatment tank 92 through the ninth pipeline 24, and a valve and a water pump can also be provided on the ninth pipeline 24; the regeneration liquid is placed in the regeneration liquid storage tank 10, and then enters the first treatment tank 2, the second treatment tank 5, and the third treatment tank 92 through the ninth pipeline 24 to respectively flush the antimony arsenic ion adsorption column, the lead ion adsorption column, and the cadmium ion adsorption column to flush away the adsorbed metal ions, and then water is added to the regeneration liquid storage tank 10 for flushing again, so that the heavy metal ion adsorption column is regenerated.

[0101] In some embodiments, a backwash drain pipe 23 is provided on the first treatment tank 2 and located above the first heavy metal ion adsorption column 3, the second treatment tank 5 and located above the second heavy metal ion adsorption column 6, and the third treatment tank 92 and located above the third heavy metal ion adsorption column 93. Obviously, a valve can be provided on the backwash drain pipe 23, and the regeneration liquid can be discharged through the backwash drain pipe 23 during the regeneration process of the heavy metal ion adsorption column.

[0102] The following further describes the method for removing heavy metal ions from wastewater by adsorption using a specific embodiment. Figure 1 The device shown is processed.

[0103] Example 1

[0104] The present invention provides a method for removing heavy metal ions from wastewater by adsorption, comprising the following steps:

[0105] S1. The water quality of the ore dressing wastewater in a certain antimony mine is as follows: Sb is 2.95 mg / L, As is 0.53 mg / L, Cd is 0.17 mg / L, Pb is 1.22 mg / L, and the raw water pH is 3.5;

[0106] S2, passing the wastewater in S1 into the first pH adjustment tank, and adjusting the pH of the wastewater to 2±0.5 using 1 mol / L hydrochloric acid solution and 1 mol / L sodium hydroxide solution;

[0107] S3, introducing the wastewater in the first pH adjustment tank into the first treatment tank, wherein a plurality of antimony arsenic ion adsorption columns are provided in the first treatment tank, the wastewater flows through the antimony arsenic ion adsorption columns and is adsorbed, and the retention time of the wastewater in the first treatment tank is controlled to be 5 hours (i.e., the adsorption time of the wastewater and the antimony arsenic ion adsorption columns is 5 hours);

[0108] S4, introducing the wastewater in the first treatment tank into the second pH adjustment tank, and adjusting the pH of the wastewater to 4.5±0.5 using 1 mol / L hydrochloric acid solution and 1 mol / L sodium hydroxide solution;

[0109] S5, introducing the wastewater in the second pH adjustment tank into the second treatment tank, wherein a plurality of lead ion adsorption columns are provided in the second treatment tank, the wastewater flows through the lead ion adsorption columns and is adsorbed, and the retention time of the wastewater in the second treatment tank is controlled to be 4.5h;

[0110] S6. The wastewater in the second treatment tank is introduced into the third pH adjustment tank, and the pH of the wastewater is adjusted to 6.52±0.5 using 1 mol / L hydrochloric acid solution and 1 mol / L sodium hydroxide solution;

[0111] S7, introducing the wastewater in the third pH adjustment tank into the third treatment tank, wherein a plurality of cadmium ion adsorption columns are provided in the third treatment tank, the wastewater flows through the cadmium ion adsorption columns and is adsorbed, and the retention time of the wastewater in the third treatment tank is controlled to be 5h;

[0112] The adsorption materials used in the above antimony arsenic ion adsorption column, lead ion adsorption column and cadmium ion adsorption column are all Fe 3 O 4 -HCO composite adsorbent, Fe 3 O 4 The preparation method of the -HCO composite adsorbent is specifically as follows:

[0113] The ground sludge raw material was dried at 300°C for 5 hours, and then crushed and ground to obtain powder particles A with a particle size of 80 to 200 meshes;

[0114] With FeSO 4 and pure water as raw materials, and a solution B with a mass ratio of 1:8 was prepared; FeCl 3 and pure water as the raw materials, and a solution C with a mass ratio of 1:4 was prepared; Fe 2+ and Fe 3+ The molar ratio is 1:2, and it is reserved;

[0115] Use pure water to dilute the concentrated ammonia water to prepare 500 volumes of 10% ammonia solution D for later use;

[0116] Under the condition of heating temperature of 60°C, nitrogen was passed through the three-necked flask for 5 to 10 minutes, and then the powder particles A, solution B, solution C and solution D were prepared into a mixed solution E in a mass ratio of 1:5:5:20 in the flask and stirred at 300 rpm for 2 hours. Nitrogen protection was required to be continuously passed through the stirring process. The generated substance was separated by a magnet and washed with deionized water and anhydrous ethanol, dried at 80°C for 12 hours, and the dried solid was ground at room temperature to obtain powder particles of 80 to 200 mesh, that is, Fe 3 O 4 -HCO composite adsorbent;

[0117] By controlling the grinding sludge and Fe ion content, the molar ratio of Ce element to Fe element in the adsorbent used in the antimony and arsenic ion adsorption column is 1:1; the molar ratio of Ce element to Fe element in the adsorbent used in the lead ion adsorption column and the cadmium ion adsorption column is 1.5:1.

[0118] After continuous and stable operation under the above working conditions, the pollutant concentrations of each adsorption column are shown in Table 1. As shown in Table 1, antimony and arsenic ions are mainly removed in the antimony arsenic ion adsorption column; lead ions are mainly removed in the lead ion adsorption column; cadmium ions are mainly removed in the cadmium ion adsorption column. After treatment, the effluent concentrations of Sb(V), As(V), Pb(II), and Cd(II) are 0.13 mg / L, 0.03 mg / L, 0.10 mg / L, and 0.01 mg / L, respectively. The total removal rates of Sb(V), As(V), Pb(II), and Cd(II) are 95.59%, 94.34%, 91.80%, and 94.12%, respectively. Except for Sb, all other removal rates can meet the relevant emission standards.

[0119] Table 1 - Influent and effluent concentrations of various heavy metal ions and environmental standards

[0120]

[0121] This embodiment also provides a method for regenerating the adsorption column, comprising the following steps:

[0122] In the above embodiment 1, the operation was continued stably for 10 days under the above working conditions, and the water intake was stopped; 0.1 mol / L sodium hydroxide solution was added to the antimony arsenic ion adsorption column, the lead ion adsorption column and the cadmium ion adsorption column, and the columns were soaked for 5 hours, and then the adsorption columns were rinsed three times with clean water to achieve the regeneration of the adsorption columns;

[0123] The above regenerated adsorption column is further used to remove Sb(V), As(V), Pb(II), and Cd(II) ions in the mining wastewater of the antimony mine area, and steps S2 to S6 are repeated 3 times. The test results show that after 3 times of adsorption, regeneration and desorption treatment, the removal rate of Sb(V), As(V), Pb(II), and Cd(II) ions by the process of the present invention is shown in Table 2.

[0124] Table 2 - Changes in removal rates of As(V), Sb(V), Pb(II), and Cd(II) during adsorption / desorption of adsorption columns

[0125] Contaminants / cycles 0 1 2 3 As(V) 94.34 90.59 87.91 83.64 Sb(V) 95.59 89.28 85.69 83.33 Pb(Ⅱ) 91.80 88.09 85.41 84.61 Cd(Ⅱ) 94.12 90.09 85.91 83.39

[0126] Example 2

[0127] The present invention provides a method for removing heavy metal ions from wastewater by adsorption, comprising the following steps:

[0128] S1. The water quality of mining wastewater in a certain antimony mine is as follows: Sb is 25.55 mg / L, As is 12.57 mg / L, Pb is 4.78 mg / L, Cd is 1.86 mg / L, and the raw water pH is 5.0;

[0129] S2, passing the wastewater in S1 into the first pH adjustment tank, and adjusting the pH of the wastewater to 2±0.5 using 1 mol / L hydrochloric acid solution and 1 mol / L sodium hydroxide solution;

[0130] S3, introducing the wastewater in the first pH adjustment tank into the first treatment tank, wherein a plurality of antimony arsenic ion adsorption columns are provided in the first treatment tank, the wastewater flows through the antimony arsenic ion adsorption columns and is adsorbed, and the retention time of the wastewater in the first treatment tank is controlled to be 10 hours (i.e., the adsorption time of the wastewater and the antimony arsenic ion adsorption columns is 10 hours);

[0131] S4, introducing the wastewater in the first treatment tank into the second pH adjustment tank, and adjusting the pH of the wastewater to 4.5±0.5 using 1 mol / L hydrochloric acid solution and 1 mol / L sodium hydroxide solution;

[0132] S5, introducing the wastewater in the second pH adjustment tank into the second treatment tank, wherein a plurality of lead ion adsorption columns are provided in the second treatment tank, the wastewater flows through the lead ion adsorption columns and is adsorbed, and the retention time of the wastewater in the second treatment tank is controlled to be 6 hours;

[0133] S6, introducing the wastewater in the second treatment tank into the third pH adjustment tank, and adjusting the pH of the wastewater to 7.0±0.5 using 1 mol / L hydrochloric acid solution and 1 mol / L sodium hydroxide solution;

[0134] S7, the wastewater in the third pH adjustment tank is introduced into the third treatment tank, the third treatment tank is provided with a plurality of cadmium ion adsorption columns, the wastewater flows through the cadmium ion adsorption columns and is adsorbed, and the retention time of the wastewater in the third treatment tank is controlled to be 6h;

[0135] The adsorption materials used in the above antimony arsenic ion adsorption column, lead ion adsorption column and cadmium ion adsorption column are all Fe 3 O 4 -HCO composite adsorbent, Fe 3 O 4 The preparation method of the -HCO composite adsorbent is specifically as follows:

[0136] The ground sludge raw material was dried at 300°C for 5 hours, and then crushed and ground to obtain powder particles A with a particle size of 80 to 200 meshes;

[0137] With FeSO 4 and pure water as raw materials, and a solution B with a mass ratio of 1:8 was prepared; FeCl 3and pure water as the raw materials, and a solution C with a mass ratio of 1:4 was prepared; Fe 2+ and Fe 3+ The molar ratio is 1:2, and it is reserved;

[0138] Use pure water to dilute the concentrated ammonia water to prepare 500 volumes of 10% ammonia solution D for later use;

[0139] Under the condition of heating temperature of 60°C, nitrogen was passed through the three-necked flask for 5 to 10 minutes, and then the powder particles A, solution B, solution C and solution D were prepared into a mixed solution E in a mass ratio of 1:5:5:20 in the flask and stirred at 300 rpm for 2 hours. Nitrogen protection was required to be continuously passed through the stirring process. The generated substance was separated by a magnet and washed with deionized water and anhydrous ethanol, dried at 80°C for 12 hours, and the dried solid was ground at room temperature to obtain powder particles of 80 to 200 mesh, that is, Fe 3 O 4 -HCO composite adsorbent;

[0140] By controlling the grinding sludge and Fe ion content, the molar ratio of Ce element to Fe element in the adsorbent used in the antimony and arsenic ion adsorption column is 1:1; the molar ratio of Ce element to Fe element in the adsorbent used in the lead ion adsorption column and the cadmium ion adsorption column is 1.5:1.

[0141] After continuous and stable operation under the above working conditions, the pollutant concentrations of each level of adsorption column are shown in Table 3. As shown in Table 3, antimony and arsenic ions are mainly removed in the antimony arsenic ion adsorption column; lead ions are mainly removed in the lead ion adsorption column; cadmium ions are mainly removed in the cadmium ion adsorption column. After treatment, the effluent concentrations of Sb(V), As(V), Pb(II), and Cd(II) are 0.85 mg / L, 0.30 mg / L, 0.35 mg / L, and 0.08 mg / L, respectively. The total removal rates of Sb(V), As(V), Pb(II), and Cd(II) are 96.67%, 97.61%, 92.68%, and 95.70%, respectively. Except for Sb, all other wastewaters can meet the relevant emission standards.

[0142] Table 3 - Influent and effluent concentrations of various heavy metal ions and environmental standards

[0143]

[0144] This embodiment also provides a method for regenerating the adsorption column, comprising the following steps:

[0145] In the above embodiment 2, the operation was continued stably for 10 days under the above working conditions, and the water intake was stopped; 0.5 mol / L sodium hydroxide solution was added to the antimony arsenic ion adsorption column, the lead ion adsorption column and the cadmium ion adsorption column, and the columns were soaked for 6 hours, and then the adsorption columns were rinsed three times with clean water to achieve the regeneration of the adsorption columns;

[0146] The above regenerated adsorption column is further used to remove Sb(V), As(V), Pb(II), and Cd(II) ions in the mining wastewater of the antimony mine area, and steps S2 to S6 are repeated 3 times. The test results show that after 3 times of adsorption, regeneration and desorption treatment, the removal rate of Sb(V), As(V), Pb(II), and Cd(II) ions by the process of the present invention is shown in Table 4.

[0147] Table 4 - Changes in removal rates of As(V), Sb(V), Pb(II), and Cd(II) during adsorption / desorption of adsorption columns

[0148] Contaminants / cycles 0 1 2 3 Sb(V) 96.67 90.63 86.73 82.15 As(V) 97.61 91.34 88.73 86.65 Pb(Ⅱ) 92.68 89.21 86.52 83.16 Cd(Ⅱ) 95.7 91.05 84.26 80.12

[0149] Comparative Example 1

[0150] This comparative example provides a method for removing heavy metal ions from artificial synthetic wastewater by adsorption, comprising the following steps:

[0151] S1. In order to investigate the competitive adsorption relationship between As(V), Sb(V), Pb(II), and Cd(II) ions, heavy metal wastewater containing As(V), Sb(V), Pb(II), and Cd(II) ions was artificially synthesized according to the water quality characteristics of mining wastewater in a certain antimony mining area. The water quality is as follows: Sb is 20.00 mg / L, As is 20.00 mg / L, Pb is 20.00 mg / L, Cd is 20.00 mg / L, and pH is 5.0;

[0152] S2, take three portions of the wastewater in S1, and use 1 mol / L hydrochloric acid solution and 1 mol / L sodium hydroxide solution to adjust the pH of the wastewater to 2±0.5, 4±0.5 and 7±0.5 respectively;

[0153] S3, three portions of wastewater adjusted with pH values ​​of 2±0.5, 4±0.5 and 7±0.5 by S2 are introduced into three first treatment tanks respectively, wherein a plurality of antimony arsenic ion adsorption columns are provided in the first treatment tank, the wastewater flows through the antimony arsenic ion adsorption columns and competitive adsorption and removal of various ions are achieved in the columns, and the retention time of the wastewater in the first treatment tank is controlled to be 10 hours (i.e., the adsorption time of the wastewater and the antimony arsenic ion adsorption columns is 10 hours);

[0154] The adsorption material used in the antimony arsenic ion adsorption column is Fe 3 O 4 -HCO composite adsorbent, Fe 3 O 4The preparation method of the -HCO composite adsorbent is specifically as follows:

[0155] The ground sludge raw material was dried at 300°C for 5 hours, and then crushed and ground to obtain powder particles A with a particle size of 80 to 200 meshes;

[0156] With FeSO 4 and pure water as raw materials, and a solution B with a mass ratio of 1:8 was prepared; FeCl 3 and pure water as the raw materials, and a solution C with a mass ratio of 1:4 was prepared; Fe 2+ and Fe 3+ The molar ratio is 1:2, and it is reserved;

[0157] Use pure water to dilute the concentrated ammonia water to prepare 500 volumes of 10% ammonia solution D for later use;

[0158] Under the condition of heating temperature of 60°C, nitrogen was passed through the three-necked flask for 5 to 10 minutes, and then the powder particles A, solution B, solution C and solution D were prepared into a mixed solution E in a mass ratio of 1:5:5:20 in the flask and stirred at 300 rpm for 2 hours. Nitrogen protection was required to be continuously passed through the stirring process. The generated substance was separated by a magnet and washed with deionized water and anhydrous ethanol, dried at 80°C for 12 hours, and the dried solid was ground at room temperature to obtain powder particles of 80 to 200 mesh, that is, Fe 3 O 4 -HCO composite adsorbent;

[0159] By controlling the grinding sludge and Fe ion content, the molar ratio of Ce element to Fe element in the adsorbent used in the antimony arsenic ion adsorption column is 1:1.

[0160] After continuous and stable operation under the above working conditions, the pollutant concentrations of each level of adsorption column are shown in Table 5.

[0161] Table 5 - Influent and effluent concentrations and removal rates of various heavy metal ions

[0162]

[0163] It can be seen from Table 5 that when the pH is 2, after only one stage treatment tank adsorption (i.e. competitive adsorption) treatment, the effluent concentrations of As(V), Sb(V), Pb(II) and Cd(II) are 5.44 mg / L, 4.00 mg / L, 13.95 mg / L and 16.14 mg / L respectively; the total removal rates of As(V), Sb(V), Pb(II) and Cd(II) are 72.80%, 80.00%, 30.25% and 19.30% respectively. Since the concentrations of As(V), Sb(V), Pb(II), and Cd(II) are all 20 mg / L, there is competitive adsorption of the four heavy metal ions, and the concentration of As(V) is much higher than the concentration of As(V) in Example 2 (12.57 mg / L), the adsorption removal rates of As(V) and Sb(V) ions are reduced compared with Example 2. Since the concentrations of the four heavy metal ions in Comparative Example 1 are all 20 mg / L), there is greater competitive adsorption compared with Example 2, which leads to a decrease in the adsorption removal rates of As(V) and Sb(V) ions; in general, when the pH is 2, As(V) and Sb(V) are still mainly adsorbed and removed, and the selective adsorption removal of As(V) and Sb(V) at pH 2 is well achieved.

[0164] When the pH is 4, after only one stage of treatment tank adsorption (i.e. competitive adsorption) treatment, the effluent concentrations of As(V), Sb(V), Pb(II), and Cd(II) are 2.49 mg / L, 14.91 mg / L, 1.42 mg / L, and 12.36 mg / L, respectively, and the total removal rates of Sb(V), As(V), Pb(II), and Cd(II) are 87.55%, 25.45%, 92.90%, and 38.20%, respectively. Since the concentrations of the four ions of As(V), Sb(V), Pb(II), and Cd(II) are all 20 mg / L, there is competitive adsorption of the four heavy metal ions, and compared with Example 2, the adsorption removal rates of Pb(II) and As(V) ions are reduced. In general, when the pH is 4, the removal is mainly based on the adsorption of Pb(Ⅱ) and As(Ⅴ), which better reflects the selective adsorption and removal of Pb(Ⅱ).

[0165] When the pH is 7, after only one stage of treatment tank adsorption (competitive adsorption) treatment, the effluent concentrations of As(V), Sb(V), Pb(II), and Cd(II) are 4.15 mg / L, 19.91 mg / L, 2.51 mg / L, and 6.40 mg / L, respectively, and the total removal rates of Sb(V), As(V), Pb(II), and Cd(II) are 79.25%, 0.45%, 87.45%, and 68.00%, respectively. Since the concentrations of As(V), Sb(V), Pb(II), and Cd(II) are all 20 mg / L, there is competitive adsorption of the four heavy metal ions, and the initial concentration of Cd(II) (20 mg / L) is much higher than the concentration of Cd(II) ions (1.86 mg / L) in Example 2, the adsorption removal rate of Cd(II) ions decreases compared with Example 2. In general, when the pH value is 7, the adsorption and removal of Cd(Ⅱ) is still relatively high, which better reflects the selective adsorption and removal of Cd(Ⅱ).

[0166] By comparing the above Examples 1 to 2 with Comparative Example 1, it can be seen that after pH adjustment, the selective adsorption removal rate of Sb(V), As(V), Pb(II), and Cd(II) is significantly higher than the competitive adsorption removal rate. Therefore, by adjusting the pH, the selective adsorption removal of Sb(V), As(V), Pb(II), and Cd(II) in heavy metal wastewater can be better achieved.

[0167] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for removing heavy metal ions from wastewater by adsorption, characterized in that: The following steps are involved: Passing the heavy metal wastewater into the first pH adjustment tank, and adjusting the pH of the wastewater to 2-4; The wastewater in the first pH adjustment tank is introduced into a first treatment tank, wherein a plurality of antimony arsenic ion adsorption columns are provided in the first treatment tank, and the wastewater flows through the antimony arsenic ion adsorption columns and is adsorbed; The wastewater in the first treatment tank is introduced into the second pH adjustment tank, and the pH of the wastewater is adjusted to 4-6; The wastewater in the second pH adjustment tank is introduced into a second treatment tank, wherein a plurality of lead ion adsorption columns are provided in the second treatment tank, and the wastewater flows through the lead ion adsorption columns and is adsorbed; The wastewater in the second treatment tank is introduced into the third pH adjustment tank, and the pH of the wastewater is adjusted to 6-9; The wastewater in the third pH adjustment tank is introduced into a third treatment tank, wherein a plurality of cadmium ion adsorption columns are provided in the third treatment tank, and the wastewater flows through the cadmium ion adsorption columns and is adsorbed; Among them, the adsorption materials used in the antimony arsenic ion adsorption column, the lead ion adsorption column, and the cadmium ion adsorption column are all Fe3O4-HCO composite adsorbent; The preparation method of the Fe3O4-HCO composite adsorbent comprises the following steps: 100 parts by weight of the ground sludge raw material is taken, dried at 100 to 500° C. for 2 to 8 hours, crushed and ground to obtain powder particles A with a particle size of 80 to 200 meshes, which are set aside; With FeSO4 and pure water as raw materials, a solution B with a mass ratio of 1:5 to 1:10 is prepared; then with FeCl3 and pure water as raw materials, a solution C with a mass ratio of 1:3 to 1:5 is prepared; wherein: the Fe in solution B and solution C 2+ and Fe 3+ The molar ratio is 1:1 to 1:3, and it is reserved; Use pure water to dilute the concentrated ammonia water to prepare 500 parts by volume of an ammonia solution D with a concentration of 5% to 15 vol%, for standby use; wherein the volume of the ammonia water and the mass of the grinding sludge are based on ml:g; Under the condition of heating temperature of 50-100° C., nitrogen is passed through the reactor for 5-10 minutes, and then powder particles A, solution B, solution C and solution D are respectively added into the reactor in proportion, stirred and mixed to prepare solution E, and then the temperature is kept constant, and the stirring reaction is continued at a speed of 150-500 rpm for 1-5 hours. Nitrogen protection needs to be continuously passed through during the stirring process. The product is separated by a magnet, washed with deionized water and anhydrous ethanol, and then dried at 50-100° C. for 8-24 hours. Finally, the dried solid is ground at room temperature to obtain powder particles of 80-200 mesh, which is a Fe3O4-HCO3 composite adsorbent; the sludge contains rare earth oxides of lanthanum and cerium, SiO2 and Al2O3; The molar ratio of Ce element to Fe element in the adsorbent used in the antimony arsenic ion adsorption column is 1:1; the molar ratio of Ce element to Fe element in the adsorbent used in the lead ion adsorption column and the cadmium ion adsorption column is 1.5:

1.

2. The method for removing heavy metal ions from wastewater by adsorption according to claim 1, characterized in that: The wastewater flows through the antimony and arsenic ion adsorption column and remains for 4 to 10 hours; the wastewater flows through the lead ion adsorption column and remains for 4 to 10 hours; the wastewater flows through the cadmium ion adsorption column and remains for 4 to 10 hours.

3. The method for removing heavy metal ions from wastewater by adsorption according to claim 1, characterized in that: The pH of the wastewater is adjusted to 2-4 or 4-6 using hydrochloric acid or sulfuric acid.

4. The method for removing heavy metal ions from wastewater by adsorption according to claim 1, characterized in that: The pH of the wastewater is adjusted to 6-9 using hydrochloric acid or sulfuric acid and sodium hydroxide or calcium oxide.

5. A method for regenerating an adsorbent material used in the method for removing heavy metal ions from wastewater by adsorption as claimed in claim 1, characterized in that: The method comprises the following steps: respectively passing the regeneration liquid into the first treatment tank, the second treatment tank and the third treatment tank, allowing the regeneration liquid to flow through the antimony arsenic ion adsorption column, the lead ion adsorption column and the cadmium ion adsorption column and cleaning the adsorption column; wherein the regeneration liquid is a sodium hydroxide solution or a hydrochloric acid solution.

6. The method for regenerating an adsorbent material according to claim 5, characterized in that: After the adsorption column is cleaned with the regeneration liquid, the method further includes: respectively passing water into the first treatment tank, the second treatment tank, and the third treatment tank, so that the water flows through the antimony arsenic ion adsorption column, the lead ion adsorption column, and the cadmium ion adsorption column to clean the adsorption column.

7. The method for regenerating an adsorbent material according to claim 5, characterized in that: The concentration of the sodium hydroxide solution is 0.1 to 1.0 mol / L, and the concentration of the hydrochloric acid solution is 0.1 to 1.0 mol / L.

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