Preparation method of red mud colloid and application of red mud colloid in heavy metal wastewater treatment

Abstract

The invention belongs to the technical field of environmental protection, and particularly discloses a preparation method of red mud colloid and application of the red mud colloid in heavy metal wastewater treatment.The preparation method comprises the steps that red mud of different masses is dispersed in water to obtain red mud turbid liquid; and simply filtering the red mud turbid liquid to obtain red mud colloid. The uniform and stable red mud colloid is obtained by adjusting the mass ratio of the red mud to the water and the temperature. The red mud colloid disclosed by the invention can efficiently adsorb heavy metal ions in water, can keep a good treatment effect under the condition of high-concentration heavy metal ions, and is suitable for high economic benefit requirements in industrial heavy metal wastewater treatment; and in the treatment process, the red mud colloid and the heavy metal ions are combined to quickly generate precipitates and quickly separate solid from liquid, so that secondary pollution to the environment is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental protection and relates to a method for preparing red mud colloid and application of the red mud colloid in heavy metal wastewater treatment. Background Art

[0002] Red mud is an industrial solid waste generated during alumina production. Currently, red mud is produced at a rate of 175.5 million tons per year, and global red mud stocks approach 4 billion tons. However, only a limited amount of red mud is reused globally; the vast majority is stored in landfills. Land storage has been the primary method for disposing of large quantities of red mud. However, due to the high alkalinity of red mud, long-term storage not only consumes significant land resources but also causes air pollution and soil alkalinization, thereby contaminating groundwater. The environmental pressures associated with long-term red mud storage have also, to a certain extent, constrained the development of the aluminum industry.

[0003] Heavy metal wastewater primarily originates from wastewater discharged by mining, smelting, electrolysis, electroplating, pesticide, pharmaceutical, and paint companies. These toxic heavy metals, including lead, nickel, cadmium, arsenic, and mercury, exist in the environment in ionic form. Since heavy metals cannot be decomposed or destroyed, they can only migrate and change their physical and chemical forms. Once in the environment or ecosystem, heavy metals in various chemical states or forms can persist, accumulate, and migrate, causing harm.

[0004] Lyu et al. modified red mud and applied it to adsorb Pb in aqueous solution. 2+ ions, modified red mud to Pb 2+ The adsorption capacity of ions is significantly improved, but the preparation process uses a hydrothermal method and a high-concentration sodium hydroxide solution, which increases production costs and poses a safety hazard.

[0005] Dong et al. directly converted red mud into magnetic adsorbent, which showed excellent Zn 2+ However, the preparation process is carried out under high temperature and high pressure, the synthesis time is long, and the large amount of reducing agent used reduces the economic benefits of the adsorbent.

[0006] Both of these studies focus on complex modifications of raw red mud. The use of high-concentration reagents and high-temperature, high-pressure treatments poses environmental risks, cost-effectiveness, and instability issues in the modified results. Furthermore, these efforts fail to effectively increase red mud utilization. Therefore, a method is urgently needed that fully utilizes the resource content of red mud, offers a simple preparation process, and is easily scalable. This method could provide a new solution for the simultaneous treatment of red mud and heavy metal-contaminated wastewater. Summary of the Invention

[0007] To solve the problems existing in the prior art, the present invention proposes a method for preparing red mud colloid and its application in heavy metal wastewater treatment. Water is used as the liquid phase to mix and stir with red mud, avoiding the use of organic solvents, reducing production costs, improving production safety, and solving the problems mentioned in the above background technology.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing red mud colloid, which is based on simple mechanical mixing and is implemented in the following steps:

[0009] Step 1: drying, grinding, and sieving the red mud to obtain a red mud pre-treated material for later use;

[0010] Step 2: adding the red mud pretreatment material to water in a certain mass ratio and stirring to obtain a red mud suspension;

[0011] Step 3: Filter the red mud suspension obtained in step 2, and take the filtered liquid portion to obtain red mud colloid.

[0012] Preferably, the red mud in step 1 comprises any one of Bayer process red mud, sintering process red mud and combined process red mud, and the particle size of the pretreated material is less than 500 μm. Preferably, the particle size of the pretreated material is less than 300 μm.

[0013] Preferably, the mass ratio of the red mud pretreatment material to water in step 2 is 0.01-6:1-200.

[0014] Preferably, the mass ratio of red mud pretreatment material to water is 3:1-10.

[0015] Preferably, in step 2, the stirring speed is 100 to 2000 rpm, the stirring time is 0.1 to 36 h, and the stirring temperature is -20 to 110°C.

[0016] Preferably, the stirring speed is 300-600 rpm, and the stirring time is 10-16 hours.

[0017] Preferably, the pore size of the filtration in step 3 is 0.1 to 50 μm. Preferably, the pore size of the filtration is 10 to 25 μm.

[0018] On the other hand, to achieve the above-mentioned purpose, the present invention also provides the following technical solution: an application of red mud colloid in the treatment of heavy metal wastewater, mixing the red mud colloid with heavy metal wastewater in a certain volume ratio, and letting it stand at a constant temperature to achieve the removal of heavy metal ions in the heavy metal wastewater.

[0019] Preferably, the pH range of the heavy metal wastewater is 1 to 7. Preferably, the pH range of the heavy metal wastewater is 3 to 5.

[0020] Preferably, in step 4, the volume ratio of red mud colloid to heavy metal wastewater is 0.1 to 5: 1. Preferably, the volume ratio of red mud colloid to heavy metal wastewater is 0.5 to 3: 1.

[0021] Preferably, the standing time in step 4 is 0.05 to 24 hours. Preferably, the standing time is 4 to 12 hours.

[0022] Preferably, the standing temperature in step 4 is 0-95° C. Preferably, the standing temperature is 10-65° C.

[0023] Preferably, the heavy metal wastewater is wastewater containing one or a mixture of tin, cadmium, lead, copper, silver, nickel and zinc.

[0024] Preferably, the red mud colloid has a removal rate of ≥90% for heavy metal ions in heavy metal wastewater.

[0025] The beneficial effects of the present invention are:

[0026] 1) Compared with existing wastewater treatment reagents, the manufacturing process of traditional wastewater treatment reagents involves multiple chemical reactions, requires harsh conditions such as high temperature and high pressure, and has high requirements for equipment and high energy consumption, which further increases production costs. The present invention only uses water as the liquid phase to mix and stir with red mud, avoiding complex chemical reactions and the use of expensive production equipment. It is an omission invention, reduces production costs, and improves production safety.

[0027] 2) When preparing traditional wastewater treatment reagents, their production relies on specific chemical raw materials. The market prices of these raw materials fluctuate greatly, and some raw materials are scarce, resulting in high reagent costs. In addition, some traditional reagents will produce secondary pollution after use, requiring additional treatment, which increases environmental governance costs. The present invention can fully utilize the resource content of red mud, an industrial solid waste generated during the alumina production process. The raw materials are readily available, and the preparation process is simple. It can provide a simultaneous treatment method for the problems of red mud accumulation and heavy metal-contaminated wastewater treatment and discharge. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The morphology of the red mud colloid obtained in Examples 1 to 3;

[0029] Figure 2 This is a Tyndall effect diagram of the red mud colloid obtained in Examples 1 to 3;

[0030] Figure 3 This is the XRD pattern of the red mud colloid obtained in Example 1;

[0031] Figure 4 This is the XRD pattern of the red mud colloid obtained in Example 2;

[0032] Figure 5This is the XRD pattern of the red mud colloid obtained in Example 3;

[0033] Figure 6 The morphology of the red mud colloid obtained in Examples 4 and 5 is shown;

[0034] Figure 7 This is a Tyndall effect diagram of the red mud colloid obtained in Examples 4 and 5;

[0035] Figure 8 This is the XRD pattern of the red mud colloid obtained in Example 4;

[0036] Figure 9 This is a diagram showing the effect of red mud colloid in removing heavy metal ions from cadmium and lead mixed heavy metal wastewater in Example 4;

[0037] Figure 10 This is the XRD pattern of the red mud colloid obtained in Example 5;

[0038] Figure 11 This is a diagram showing the effect of using red mud colloid to remove heavy metal ions from tin and copper mixed heavy metal wastewater in Example 5;

[0039] Figure 12 The morphology of the red mud colloid obtained in Examples 6 and 7;

[0040] Figure 13 This is a Tyndall effect diagram of the red mud colloid obtained in Examples 6 and 7;

[0041] Figure 14 This is the XRD pattern of the red mud colloid obtained in Example 6;

[0042] Figure 15 This is a diagram showing the effect of red mud colloid in removing heavy metal ions from zinc, copper and lead mixed heavy metal wastewater in Example 6;

[0043] Figure 16 This is the XRD pattern of the red mud colloid obtained in Example 7;

[0044] Figure 17 This is a diagram showing the effect of red mud colloid in removing heavy metal ions from mixed heavy metal wastewater containing cadmium, lead and nickel in Example 7;

[0045] Figure 18 This is the appearance morphology of the red mud colloid obtained in Example 8;

[0046] Figure 19 This is a Tyndall effect diagram of the red mud colloid obtained in Example 8;

[0047] Figure 20 This is the XRD pattern of the red mud colloid obtained in Example 8;

[0048] Figure 21This is a diagram showing the effect of red mud colloid in removing heavy metal ions from mixed heavy metal wastewater containing lead, copper, silver and nickel in Example 8;

[0049] Figure 22 This is the appearance morphology of the red mud colloid obtained in Example 9;

[0050] Figure 23 This is a Tyndall effect diagram of the red mud colloid obtained in Example 9;

[0051] Figure 24 This is the XRD pattern of the red mud colloid obtained in Example 9;

[0052] Figure 25 This is a diagram showing the effect of red mud colloid in removing heavy metal ions from mixed heavy metal wastewater containing lead, copper, silver, nickel and zinc in Example 9;

[0053] Figure 26 This is the appearance morphology of the red mud colloid obtained in Example 10;

[0054] Figure 27 This is a Tyndall effect diagram of the red mud colloid obtained in Example 10;

[0055] Figure 28 This is the XRD pattern of the red mud colloid obtained in Example 10;

[0056] Figure 29 This is a diagram showing the effect of red mud colloid in removing heavy metal ions from mixed heavy metal wastewater containing cadmium, lead, copper, silver, nickel and zinc in Example 10;

[0057] Figure 30 This is a diagram showing the effect of modified red mud in removing heavy metal ions from mixed heavy metal wastewater containing lead, copper, silver, nickel and zinc in Comparative Example 1;

[0058] Figure 31 This is a diagram showing the effect of modified red mud in comparative example 2 in removing heavy metal ions from mixed heavy metal wastewater containing lead, copper, silver, nickel and zinc. DETAILED DESCRIPTION

[0059] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0060] Example 1

[0061] (1) The red mud is placed in a 120°C forced air drying oven and dried for 12 hours. The dried red mud is ground and sieved to less than 300 μm to obtain a red mud pretreated material for later use;

[0062] (2) Weigh 50 g of red mud pretreatment material and 200 g of water, place them in a 500 mL beaker, and magnetically stir them in a water bath at 300 rpm and 25 °C for 12 h to obtain a red mud suspension;

[0063] (3) Pour the red mud suspension into a Buchner funnel padded with 25 μm filter and filter, and take the filtered liquid to obtain red mud colloid;

[0064] (4) 20 mL of red mud colloid was added to 10 mL of simulated lead-contaminated water, where the initial lead concentration in the simulated lead-contaminated water was 1000 mg / L and the pH was 4.5. After mixing, the mixture was allowed to stand in a water bath at 25 °C for 10 h.

[0065] The red mud colloid obtained in Example 1 is as follows Figure 1 As shown in A. The Tyndall effect of the red mud colloid obtained in Example 1 was tested, and the obtained Tyndall phenomenon diagram is shown in Figure 2 Middle A.

[0066] The dry powder of the red mud colloid obtained in Example 1 was subjected to X-ray diffraction test, and the obtained XRD pattern is shown in FIG. Figure 3 .Depend on Figure 3 It can be seen that the X-ray diffraction peak of the red mud colloid in Example 1 is a diffraction peak of a complex mineral phase.

[0067] The concentration of lead ions in the mixed solution after standing in Example 1 was tested. The removal rate of lead ions in lead-containing heavy metal wastewater by red mud colloid was above 99.5%, which verified the application potential of red mud colloid in treating lead-containing heavy metal wastewater.

[0068] Example 2

[0069] (1) The red mud is placed in a 120°C forced air drying oven and dried for 12 hours. The dried red mud is ground and sieved to less than 300 μm to obtain a red mud pretreated material for later use;

[0070] (2) Weigh 100 g of red mud pretreated material and 200 g of water, place them in a 500 mL beaker, and magnetically stir them in a water bath at 600 rpm and 35 °C for 10 h to obtain a red mud suspension;

[0071] (3) Pour the red mud suspension into a Buchner funnel padded with 30 μm filter and filter, and take the filtered liquid to obtain red mud colloid;

[0072] (4) 10 mL of red mud colloid was added to 20 mL of simulated copper-contaminated water, where the initial copper concentration in the simulated copper-contaminated water was 600 mg / L and the pH was 5.3. After mixing, the mixture was allowed to stand in a 30°C water bath for 12 h.

[0073] The red mud colloid obtained in Example 2 is as follows Figure 1The Tyndall effect of the red mud colloid obtained in Example 2 was tested, and the obtained Tyndall phenomenon diagram is shown in FIG. Figure 2 Middle B.

[0074] The dry powder of the red mud colloid obtained in Example 2 was subjected to X-ray diffraction test, and the obtained XRD pattern is shown in FIG. Figure 4 .Depend on Figure 4 It can be seen that the X-ray diffraction peak of the red mud colloid in Example 2 is a diffraction peak of a complex mineral phase.

[0075] The concentration of copper ions in the mixed solution after standing in Example 2 was tested. The removal rate of copper ions in copper-containing heavy metal wastewater by red mud colloid was above 99%, which verified the application potential of red mud colloid in treating copper-containing heavy metal wastewater.

[0076] Example 3

[0077] (1) The red mud is placed in a 120°C forced air drying oven and dried for 12 hours. The dried red mud is ground and sieved to less than 300 μm to obtain a red mud pretreated material for later use;

[0078] (2) Weigh 50 g of red mud pretreated material and 250 g of water, place them in a 500 mL beaker, and stir them magnetically in a water bath at 550 rpm and 60 °C for 8 h to obtain a red mud suspension;

[0079] (3) Pour the red mud suspension into a Buchner funnel padded with 25 μm filter and filter, and take the filtered liquid to obtain red mud colloid;

[0080] (4) 10 mL of red mud colloid was added to 10 mL of simulated nickel-contaminated water, where the initial nickel concentration in the simulated nickel-contaminated water was 120 mg / L and the pH was 5.0. After mixing, the mixture was allowed to stand in a 35°C water bath for 8 h.

[0081] The red mud colloid obtained in Example 3 is as follows Figure 1 The Tyndall effect of the red mud colloid obtained in Example 3 was tested, and the obtained Tyndall phenomenon diagram is shown in FIG. Figure 2 Middle C.

[0082] The dry powder of the red mud colloid obtained in Example 3 was subjected to X-ray diffraction test, and the obtained XRD pattern is shown in FIG. Figure 5 .Depend on Figure 5 It can be seen that the X-ray diffraction peak of the red mud colloid in Example 3 is a diffraction peak of a complex mineral phase.

[0083] The nickel ion concentration in the mixed solution after standing in Example 3 was tested. The red mud colloid had a nickel ion removal rate of more than 98% in nickel-containing heavy metal wastewater, verifying the application potential of red mud colloid in treating nickel-containing heavy metal wastewater.

[0084] Example 4

[0085] (1) The red mud is placed in a 120°C forced air drying oven and dried for 12 hours. The dried red mud is ground and sieved to less than 300 μm to obtain a red mud pretreated material for later use;

[0086] (2) Weigh 150 g of red mud pretreatment material and 100 g of water, place them in a 500 mL beaker, and magnetically stir them in a water bath at 750 rpm and 50 °C for 14 h to obtain a red mud suspension;

[0087] (3) Pour the red mud suspension into a Buchner funnel padded with 25 μm filter and filter, and take the filtered liquid to obtain red mud colloid;

[0088] (4) 30 mL of red mud colloid was added to 10 mL of simulated cadmium and lead contaminated water. The initial cadmium and lead concentrations in the simulated cadmium and lead contaminated water were 80 mg / L, respectively, and the pH was 5.5. After mixing, the mixture was placed in a 40°C water bath for 14 h.

[0089] The red mud colloid obtained in Example 4 is as follows Figure 6 The Tyndall effect of the red mud colloid obtained in Example 4 was tested, and the obtained Tyndall phenomenon diagram is shown in FIG. Figure 7 Middle A.

[0090] The dry powder of the red mud colloid obtained in Example 4 was subjected to X-ray diffraction test, and the obtained XRD pattern is shown in FIG. Figure 8 .Depend on Figure 8 It can be seen that the X-ray diffraction peak of the red mud colloid in Example 4 is a diffraction peak of a complex mineral phase.

[0091] The concentration of cadmium and lead ions in the mixed solution after standing in Example 4 was tested, and the effect of the obtained red mud colloid on removing heavy metal ions from mixed heavy metal wastewater was shown in the figure below. Figure 9 .Depend on Figure 9 It can be seen that the removal rates of cadmium and lead ions in cadmium- and lead-containing mixed heavy metal wastewater by red mud colloid are above 93.5% and 99.5% respectively, which verifies the application potential of red mud colloid in treating cadmium- and lead-containing mixed heavy metal wastewater.

[0092] Example 5

[0093] (1) The red mud is placed in a 120°C forced air drying oven and dried for 12 hours. The dried red mud is ground and sieved to less than 300 μm to obtain a red mud pretreated material for later use;

[0094] (2) Weigh 50 g of red mud pretreated material and 150 g of water, place them in a 500 mL beaker, and stir them magnetically in a water bath at 350 rpm and 75 °C for 9 h to obtain a red mud suspension;

[0095] (3) Pour the red mud suspension into a Buchner funnel padded with 20 μm filter and filter, and take the filtered liquid to obtain red mud colloid;

[0096] (4) 10 mL of red mud colloid was added to 15 mL of simulated tin and copper contaminated water. The initial tin and copper concentrations in the simulated tin and copper contaminated water were 15 mg / L and 20 mg / L, respectively, and the pH was 3.5. After mixing, the mixture was allowed to stand in a 45 °C water bath for 11 h.

[0097] The red mud colloid obtained in Example 5 is as follows Figure 6 The Tyndall effect of the red mud colloid obtained in Example 5 was tested, and the obtained Tyndall phenomenon diagram is shown in FIG. Figure 7 Middle B.

[0098] The dry powder of the red mud colloid obtained in Example 5 was subjected to X-ray diffraction test, and the obtained XRD pattern is shown in FIG. Figure 10 .Depend on Figure 10 It can be seen that the X-ray diffraction peak of the red mud colloid in Example 5 is a diffraction peak of a complex mineral phase.

[0099] The concentration of tin and copper ions in the mixed solution after standing in Example 5 was tested, and the effect of the obtained red mud colloid on removing heavy metal ions from mixed heavy metal wastewater is shown in the figure below: Figure 11 .Depend on Figure 11 It can be seen that the removal rates of tin and copper ions in tin- and copper-containing mixed heavy metal wastewater by red mud colloid are above 98.5% and 99% respectively, which verifies the application potential of red mud colloid in treating tin- and copper-containing mixed heavy metal wastewater.

[0100] Example 6

[0101] (1) The red mud is placed in a 120°C forced air drying oven and dried for 12 hours. The dried red mud is ground and sieved to less than 300 μm to obtain a red mud pretreated material for later use;

[0102] (2) Weigh 75 g of red mud pretreatment material and 100 g of water, place them in a 500 mL beaker, and stir them magnetically in a water bath at 650 rpm and 65°C for 6 h to obtain a red mud suspension;

[0103] (3) Pour the red mud suspension into a Buchner funnel padded with 25 μm filter and filter, and take the filtered liquid to obtain red mud colloid;

[0104] (4) 15 mL of red mud colloid was added to 20 mL of simulated zinc, copper, and lead contaminated water. The initial zinc, copper, and lead concentrations in the simulated zinc, copper, and lead contaminated water were 100 mg / L, respectively, and the pH was 6.0. After mixing, the mixture was allowed to stand in a 20°C water bath for 13 h.

[0105] The red mud colloid obtained in Example 6 is as follows Figure 12The Tyndall effect of the red mud colloid obtained in Example 6 was tested, and the obtained Tyndall phenomenon diagram is shown in FIG. Figure 13 Middle A.

[0106] The dry powder of the red mud colloid obtained in Example 6 was subjected to X-ray diffraction test, and the obtained XRD pattern is shown in FIG. Figure 14 .Depend on Figure 14 It can be seen that the X-ray diffraction peak of the red mud colloid in Example 6 is a diffraction peak of a complex mineral phase.

[0107] The concentration of zinc, copper and lead ions in the mixed solution after standing in Example 6 was tested, and the effect of the obtained red mud colloid on removing heavy metal ions from mixed heavy metal wastewater is shown in the figure below. Figure 15 .Depend on Figure 15 It can be seen that the removal rates of zinc, copper and lead ions in mixed heavy metal wastewater containing zinc, copper and lead by red mud colloid are above 97%, 98 and 98.5% respectively, which verifies the application potential of red mud colloid in treating mixed heavy metal wastewater containing zinc, copper and lead.

[0108] Example 7

[0109] (1) The red mud is placed in a 120°C forced air drying oven and dried for 12 hours. The dried red mud is ground and sieved to less than 300 μm to obtain a red mud pretreated material for later use;

[0110] (2) Weigh 80 g of red mud pretreatment material and 120 g of water, place them in a 500 mL beaker, and stir them magnetically in a water bath at 400 rpm and 40 °C for 11 h to obtain a red mud suspension;

[0111] (3) Pour the red mud suspension into a Buchner funnel padded with 25 μm filter and filter, and take the filtered liquid to obtain red mud colloid;

[0112] (4) 15 mL of red mud colloid was added to 10 mL of simulated cadmium, lead, and nickel contaminated water. The initial zinc, copper, and lead concentrations in the simulated cadmium, lead, and nickel contaminated water were 120 mg / L, and the pH was 5.2, respectively. After mixing, the mixture was placed in a 50°C water bath for 9 h.

[0113] The red mud colloid obtained in Example 7 is as follows Figure 11 The Tyndall effect of the red mud colloid obtained in Example 7 was tested, and the obtained Tyndall phenomenon diagram is shown in FIG. Figure 12 Middle B.

[0114] The dry powder of the red mud colloid obtained in Example 7 was subjected to X-ray diffraction test, and the obtained XRD pattern is shown in FIG. Figure 16 .Depend on Figure 16 It can be seen that the X-ray diffraction peak of the red mud colloid in Example 7 is a diffraction peak of a complex mineral phase.

[0115] The concentration of cadmium, lead and nickel ions in the mixed solution after standing in Example 7 was tested, and the effect of the obtained red mud colloid on removing heavy metal ions from mixed heavy metal wastewater is shown in the figure below. Figure 17 .Depend on Figure 17 It can be seen that the removal rates of cadmium, lead and nickel ions in mixed heavy metal wastewater containing cadmium, lead and nickel by red mud colloid are above 98%, 99.5% and 97% respectively, which verifies the application potential of red mud colloid in treating mixed heavy metal wastewater containing cadmium, lead and nickel.

[0116] Example 8

[0117] (1) The red mud is placed in a 120°C forced air drying oven and dried for 12 hours. The dried red mud is ground and sieved to less than 300 μm to obtain a red mud pretreated material for later use;

[0118] (2) Weigh 75 g of red mud pretreatment material and 200 g of water, place them in a 500 mL beaker, and magnetically stir them in a water bath at 450 rpm and 45°C for 18 h to obtain a red mud suspension;

[0119] (3) Pour the red mud suspension into a Buchner funnel padded with 25 μm filter and filter, and take the filtered liquid to obtain red mud colloid;

[0120] (4) 25 mL of red mud colloid was added to 15 mL of simulated lead, copper, silver, and nickel contaminated water. The initial zinc, copper, and lead concentrations in the simulated lead, copper, silver, and nickel contaminated water were 120 mg / L and the pH was 4.9, respectively. After mixing, the mixture was allowed to stand in a 30°C water bath for 18 h.

[0121] The red mud colloid obtained in Example 8 is as follows Figure 18 The Tyndall effect of the red mud colloid obtained in Example 8 was tested, and the obtained Tyndall phenomenon diagram is shown in FIG. Figure 19 .

[0122] The dry powder of the red mud colloid obtained in Example 8 was subjected to X-ray diffraction test, and the obtained XRD pattern is shown in FIG. Figure 20 .Depend on Figure 20 It can be seen that the X-ray diffraction peak of the red mud colloid in Example 8 is a diffraction peak of a complex mineral phase.

[0123] The concentration of lead, copper, silver and nickel ions in the mixed solution after standing in Example 8 was tested, and the effect of the obtained red mud colloid on removing heavy metal ions from mixed heavy metal wastewater was shown in the figure below. Figure 21 .Depend on Figure 21 It can be seen that the removal rates of red mud colloid for lead, copper, silver and nickel ions in mixed heavy metal wastewater containing lead, copper, silver and nickel are above 99.5%, 99.5%, 99% and 97.5% respectively, which verifies the application potential of red mud colloid in treating mixed heavy metal wastewater containing lead, copper, silver and nickel.

[0124] Example 9

[0125] (1) The red mud is placed in a 120°C forced air drying oven and dried for 12 hours. The dried red mud is ground and sieved to less than 300 μm to obtain a red mud pretreated material for later use;

[0126] (2) Weigh 100 g of red mud pretreated material and 125 g of water, place them in a 500 mL beaker, and stir them magnetically in a water bath at 380 rpm and 30 °C for 7 h to obtain a red mud suspension;

[0127] (3) Pour the red mud suspension into a Buchner funnel padded with 25 μm filter and filter, and take the filtered liquid to obtain red mud colloid;

[0128] (4) 15 mL of red mud colloid was added to 25 mL of simulated lead, copper, silver, nickel, and zinc contaminated water. The initial lead, copper, silver, nickel, and zinc concentrations in the simulated contaminated water were 60 mg / L, and the pH was 5.5. After mixing, the mixture was placed in a 15°C water bath for 6 h.

[0129] The red mud colloid obtained in Example 9 is as follows Figure 22 The Tyndall effect of the red mud colloid obtained in Example 9 was tested, and the obtained Tyndall phenomenon diagram is shown in FIG. Figure 23 .

[0130] The dry powder of the red mud colloid obtained in Example 9 was subjected to X-ray diffraction test, and the obtained XRD pattern is shown in FIG. Figure 24 .Depend on Figure 24 It can be seen that the X-ray diffraction peak of the red mud colloid in Example 9 is a diffraction peak of a complex mineral phase.

[0131] The concentration of lead, copper, silver, nickel and zinc ions in the mixed solution after standing in Example 9 was tested, and the effect of the obtained red mud colloid on removing heavy metal ions from mixed heavy metal wastewater was shown in the figure below. Figure 25 .Depend on Figure 25 It can be seen that the removal rates of red mud colloid for lead, copper, silver, nickel and zinc ions in mixed heavy metal wastewater containing lead, copper, silver, nickel and zinc are above 99.5%, 99.5%, 97.5%, 95.5% and 96% respectively, which verifies the application potential of red mud colloid in treating mixed heavy metal wastewater containing lead, copper, silver, nickel and zinc.

[0132] Example 10

[0133] (1) The red mud is placed in a 120°C forced air drying oven and dried for 12 hours. The dried red mud is ground and sieved to less than 300 μm to obtain a red mud pretreated material for later use;

[0134] (2) Weigh 100 g of red mud pretreated material and 100 g of water, place them in a 500 mL beaker, and magnetically stir them in a water bath at 500 rpm and 55 °C for 20 h to obtain a red mud suspension;

[0135] (3) Pour the red mud suspension into a Buchner funnel padded with 25 μm filter and filter, and take the filtered liquid to obtain red mud colloid;

[0136] (4) 25 mL of red mud colloid was added to 20 mL of simulated cadmium, lead, copper, silver, nickel, and zinc contaminated water. The initial cadmium, lead, copper, silver, nickel, and zinc concentrations in the simulated contaminated water were 90 mg / L, and the pH was 5.7. After mixing, the mixture was placed in a 60°C water bath for 20 h.

[0137] The red mud colloid obtained in Example 10 is as follows Figure 26 The Tyndall effect of the red mud colloid obtained in Example 10 was tested, and the obtained Tyndall phenomenon diagram is shown in FIG. Figure 27 .

[0138] The dry powder of the red mud colloid obtained in Example 10 was subjected to X-ray diffraction test, and the obtained XRD pattern is shown in FIG. Figure 28 .Depend on Figure 28 It can be seen that the X-ray diffraction peak of the red mud colloid in Example 10 is a diffraction peak of a complex mineral phase.

[0139] The concentration of cadmium, lead, copper, silver, nickel and zinc ions in the mixed solution after standing in Example 10 was tested, and the effect of the obtained red mud colloid on removing heavy metal ions from mixed heavy metal wastewater was shown in the figure below. Figure 29 .Depend on Figure 29 It can be seen that the removal rates of red mud colloid for cadmium, lead, copper, silver, nickel and zinc ions in mixed heavy metal wastewater containing cadmium, lead, copper, silver, nickel and zinc are above 97%, 99.5%, 99.5%, 98%, 95.5% and 96.5% respectively, verifying the application potential of red mud colloid in treating mixed heavy metal wastewater containing cadmium, lead, copper, silver, nickel and zinc.

[0140] Comparative Example 1

[0141] (1) Red mud was placed in a blast drying oven at 120° C. and dried for 12 h. The dried red mud was ground and sieved to less than 140 μm to obtain a red mud pretreated material for later use;

[0142] (2) Weigh 10 g of red mud pretreatment material and 100 g of 0.5 mol / L acetic acid, place them in a 250 mL beaker, and after acid treatment at 25 °C for 3 h, perform solid-liquid separation and collect the red mud residue;

[0143] (3) calcining the red mud residue in a muffle furnace at a calcination temperature of 500°C, a heating rate of 5°C / min, and calcining at a constant temperature of 500°C for 3 hours to obtain modified red mud;

[0144] (4) Weigh 0.1 g of the modified red mud in (3) and add it to 10 mL of simulated lead, copper, silver, nickel, and zinc contaminated water. The initial lead, copper, silver, nickel, and zinc concentrations in the simulated contaminated water are 40 mg / L, respectively, and the pH is 5.5. Place it on a shaker and vibrate at room temperature for 5 h. After taking it out, perform solid-liquid separation and retain the liquid.

[0145] The concentration of lead, copper, silver, nickel and zinc ions in the liquid obtained in Comparative Example 1 was tested, and the effect of the obtained red mud colloid on removing heavy metal ions from mixed heavy metal wastewater was shown in the figure below. Figure 30 .Depend on Figure 30 It can be seen that the removal rates of lead, copper, silver, nickel and zinc ions in mixed heavy metal wastewater containing lead, copper, silver, nickel and zinc are 99%, 87%, 99%, 22% and 12% respectively.

[0146] Comparative Example 2

[0147] (1) Red mud was placed in a blast drying oven at 120° C. and dried for 12 h. The dried red mud was ground and passed through an 80-mesh sieve to obtain a red mud pretreated material for later use;

[0148] (2) Weigh 25 g of red mud pretreated material and place it in a sealed container. Add 6 mol / L hydrochloric acid to the sealed container, and then acid treat it at 25°C for 15 minutes, perform solid-liquid separation, and collect the red mud residue; wash the red mud residue with water, and then dry, crush, and sieve the washed red mud residue.

[0149] (3) Weigh 1g of FeCl3 solid, 1g of CTAB solid, and 2g of urea solid particles, add them to a 1L volumetric flask, add distilled water to make up to 1L, and shake until the solids are dissolved to obtain the modified solution;

[0150] (4) Weigh 10 g of red mud acid leaching residue and add it to 1 L of the modified solution in (3), place it in a pressure vessel and heat it to about 105 ° C., keep it warm for 1 hour, and after the container cools down, filter the solution, dry the filter residue at 105 ° C. for 12 hours, grind it through an 80-mesh sieve, and obtain a modified red mud heavy metal adsorbent.

[0151] (5) Weigh 0.12 g of the modified red mud heavy metal adsorbent in (4) and add it to 20 mL of simulated lead, copper, silver, nickel, and zinc contaminated water. The initial lead, copper, silver, nickel, and zinc concentrations in the simulated contaminated water are 40 mg / L, respectively, and the pH is 5.5. Place it on a shaker and vibrate at room temperature for 3 h. After taking it out, perform solid-liquid separation and retain the liquid.

[0152] The concentration of lead, copper, silver, nickel and zinc ions in the liquid obtained in Comparative Example 2 was tested, and the effect of the obtained red mud colloid on removing heavy metal ions from mixed heavy metal wastewater was shown in the figure below. Figure 31 .Depend on Figure 31 It can be seen that the removal rates of lead, copper, silver, nickel and zinc ions in mixed heavy metal wastewater containing lead, copper, silver, nickel and zinc are 92%, 45%, 98%, 2% and 4% respectively.

[0153] Comparative verification effect

[0154] The modified red mud heavy metal adsorbents prepared in Examples 1-10 and Comparative Examples 1-2 are compared. It can be seen that in terms of the preparation process, the preparation procedure of the present invention is simple and easy to operate, and the red mud colloid can be obtained by simply mechanically stirring the red mud in water. In addition, in terms of preparation conditions, the preparation process of the present invention does not require high temperature, high pressure and other conditions, nor does it require various external reagents to modify the red mud. It is an omitted invention, which is not only economically efficient but also environmentally friendly. In addition, the red mud colloid prepared by the present invention has a good treatment effect on various heavy metal ions, and can still be treated simultaneously and efficiently even in the face of mixed wastewater with the coexistence of multiple heavy metal ions.

[0155] In summary, the present invention addresses the environmental risks, cost-effectiveness, and other issues in the preparation of traditional wastewater treatment reagents, as well as the current situation of large-scale accumulation of red mud, and proposes a red mud colloid, a preparation method thereof, and its application in the treatment of heavy metal wastewater. Red mud of different masses is dispersed in water to obtain a red mud suspension; the red mud suspension is simply filtered to obtain a red mud colloid; and a uniform and stable red mud colloid is obtained by adjusting the mass ratio of red mud to water. Water is used as the liquid phase to mix with the red mud and stir, avoiding the use of organic solvents, reducing production costs, and improving production safety. The method of the present invention can utilize the large amount of red mud accumulated in the red mud dump as raw material, fully utilizing the resource content of the red mud, and the preparation process is simple and easy to scale up, which can simultaneously solve the problems of red mud accumulation and heavy metal-contaminated wastewater discharge.

[0156] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing red mud colloid, characterized in that: Red mud colloid was prepared based on simple mechanical mixing. The specific steps are as follows: Step 1: drying, grinding, and sieving the red mud to obtain a red mud pretreated material; Step 2: adding the red mud pretreatment material to water in a certain mass ratio and stirring to obtain a red mud suspension; Step 3: Filter the red mud suspension obtained in step 2, and take the filtered liquid portion to obtain red mud colloid.

2. The method for preparing red mud colloid according to claim 1, characterized in that: The red mud in step 1 includes any one of Bayer process red mud, sintering process red mud and combined process red mud; the particle size of the pretreated material is less than 500 μm.

3. The method for preparing red mud colloid according to claim 1, characterized in that: In step 2, the mass ratio of the red mud pretreatment material to water is 0.01-6:1-200.

4. The method for preparing red mud colloid according to claim 1, characterized in that: In step 2, the stirring speed is 100 to 2000 rpm, the stirring time is 0.1 to 36 hours, and the stirring temperature is -20 to 110°C.

5. The method for preparing red mud colloid according to claim 1, characterized in that: The pore size of the filtration in step 3 is 0.1 to 50 μm.

6. Use of red mud colloid prepared according to the method for preparing red mud colloid according to any one of claims 1 to 5 in the treatment of heavy metal wastewater, characterized in that: The red mud colloid is mixed with heavy metal wastewater in a certain volume ratio and allowed to stand at a constant temperature to achieve the removal of heavy metal ions in the heavy metal wastewater.

7. The use of red mud colloid in heavy metal wastewater treatment according to claim 6, characterized in that: The pH range of the heavy metal wastewater is 1-7.

8. The use of red mud colloid in heavy metal wastewater treatment according to claim 6, characterized in that: The volume ratio of red mud colloid to heavy metal wastewater is 0.1-5:1; the standing time is 0.05-24 hours, and the standing temperature is 0-95°C.

9. The use of red mud colloid in heavy metal wastewater treatment according to claim 6, characterized in that: The heavy metal wastewater is wastewater containing one or a mixture of tin, cadmium, lead, copper, silver, nickel and zinc.

10. The use of red mud colloid in heavy metal wastewater treatment according to claim 6, characterized in that: The red mud colloid has a removal rate of heavy metal ions in heavy metal wastewater of ≥90%.

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