A functional material for removing complex heavy metals, its preparation method and application

Abstract

The present invention relates to a functional material for removing complex heavy metals, its preparation method and application, including: (1) preparing a surfactant solution, and adding a KMnO4 solution to the surfactant solution at 50-80 °C to obtain a mixed solution; (2) crushing biomass, dispersing it in water, adding it to the mixed solution in step (1), adjusting the pH value to 6-9, stirring and reacting at 20-60 °C, filtering after the reaction ends, washing and drying the solid to obtain a biomass@MnO2 functional material. The functional material provided by the present invention can simultaneously achieve the complex-breaking and adsorption and removal of complex heavy metal ions, has good removal effect, simple preparation method, and is energy-saving and environmentally friendly.

Description

Technical Field

[0001] The present invention belongs to the field of environmental governance functional materials, and particularly relates to a functional material for removing complex heavy metals, a preparation method thereof, and an application thereof. Background Art

[0002] Water environment governance has been one of the key tasks faced by humans for a long time, especially the problem of removing heavy metal ions is relatively prominent. Heavy metal ions cannot be completely removed through biodegradation and will accumulate through the food chain, posing a serious threat to the environmental ecological balance and human health. It is worth noting that heavy metal ions usually easily complex with cyanide, EDTA or other organic substances, increasing the difficulty of their treatment. Therefore, the removal of complex heavy metal ions is the key and difficult problem currently faced in wastewater treatment.

[0003] Biomass, as a waste resource with a large reserve and various types, is often used as an adsorbent material for wastewater treatment and environmental remediation due to its rich surface functional groups and hierarchical pore structure. Specifically, it is mostly used for the removal of heavy metals, radionuclides, and organic pollutants. The ways of reusing biomass waste as an adsorbent can be roughly divided into three categories: (1) preparing activated carbon adsorbent; (2) directly using it as an adsorbent; (3) using it as an adsorbent after modification. Biomass-based activated carbon, abbreviated as biomass carbon, usually needs to be prepared by means of high-temperature baking, pyrolysis, gasification or hydrothermal treatment to increase the specific surface area of the material. For biomass itself and biomass-based activated carbon, the adsorption capacity for pollutants is relatively limited, and the adsorption capacity is usually only a few milligrams to dozens of milligrams per gram, greatly limiting its application range. Therefore, biomass or biomass carbon usually needs to be further modified, and most tend to modify the surface groups, using groups such as hydroxyl and carboxyl to complex with pollutants to enhance the chemical adsorption capacity of the material. Some studies have shown that the more oxygen-containing groups in the biomass-based adsorbent, the stronger the adsorption capacity for cationic heavy metal ions (such as Cu, Pb, Zn, Ni, etc.).

[0004] Patent CN202010273439.7 discloses a modified biomass carbon and its preparation method, which includes the following steps: (1) Preparation of straw biomass carbon: Add straw raw materials into a pyrolysis carbonization furnace to obtain biomass carbon under high-temperature and oxygen-free conditions. After cooling, grinding, and sieving, it is reserved for use; (2) Nano-modification: Put biomass carbon and deionized water into a reaction kettle, and obtain nano-scale biomass carbon under high-speed stirring and ultrasonic action; (3) Oxidation modification: Adjust the pH value of the product obtained in step (2) to 5-6, and slowly add potassium permanganate powder into the above reaction kettle, and stir at low speed to obtain oxidized nano-scale biomass carbon; (4) Place the reaction product obtained in step (3) in an environment of 60 °C and dry it to constant weight, then cool it and crush it to 100 meshes. This patent realizes the oxidation modification of the surface of biomass carbon with the help of KMnO4 under acidic conditions. At this time, KMnO4 is reduced to Mn 2+ , and is used for the remediation of heavy metal ion-polluted soil. However, this material mainly realizes the adsorption and removal of free heavy metal ions and cannot effectively remove complex heavy metal ions.

[0005] CN201610146572.X provides a biomass adsorbent, and its preparation method includes: Step 1: Wash corn husks to remove the soil and impurities on the surface, soak them in water to remove soluble substances, dry them, cut the corn husks into pieces with scissors, and put them into bags for standby; Step 2: Soak the corn husks obtained in Step 1 in a modifier potassium permanganate solution, place them in a constant temperature oven at 75-85 °C, stand still for 55-65 min, filter, wash, and dry to obtain potassium permanganate-modified corn husks as a biomass adsorbent. This biomass adsorbent is used to treat cadmium-containing wastewater, and the cadmium therein is free heavy metal ions, and the removal effect for complex heavy metal ions is not good.

[0006] At present, the general treatment idea for complex heavy metal ions is to pre-break the complexation, and then use the methods for treating free heavy metal ions conventionally for treatment. It is necessary to cooperate with a variety of methods and processes to comprehensively treat the wastewater. Therefore, the research and development of new multifunctional materials has gradually become the solution to the problem of treating complex heavy metal ions.

[0007] Patent CN201910939573.3 discloses a nano-manganese oxide modified biochar and its preparation method. By combining the respective advantages of biochar and manganese oxides (manganese oxides include manganese dioxide, manganese sesquioxide, and manganese tetraoxide), a nano-manganese oxide modified biochar composite material is synthesized as an adsorbent to treat water bodies contaminated with complex heavy metals. The invention also discloses a method for removing copper citrate using nano-manganese oxide modified biochar. During the adsorption process, copper citrate reacts with manganese sesquioxide on the surface of the biochar to form a new chemical bond -Cu-O-Mn-O-. Manganese sesquioxide with strong oxidation ability oxidizes citric acid into low molecular weight organic acid substances, realizing the breaking of the complexation of copper citrate, and the released copper is removed by the manganese oxide modified biochar. Based on its mechanism research, the manganese oxide exists in the form of manganese sesquioxide and plays its removal role. Furthermore, citric acid is a reducing substance and can undergo an oxidation-reduction reaction with manganese oxide to realize the breaking of the complexation of complex heavy metal ions. However, for complexing substances such as ethylenediaminetetraacetic acid (EDTA) or cyanide (CN) with no obvious reducibility or weak reducibility, manganese oxide is not easy to undergo an oxidation-reduction reaction with the above substances, and the breaking of the complexation of complex heavy metal ions cannot be achieved. Therefore, this adsorbent material is not suitable for the removal of such complex heavy metal ions. Summary of the Invention

[0008] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a functional material for removing complex heavy metals, its preparation method and application. The functional material provided by the present invention can simultaneously realize the breaking of the complexation and adsorption and removal of complex heavy metal ions, with good removal effect, simple preparation method, energy-saving and environmental protection.

[0009] The preparation method of a functional material for removing complex heavy metals provided by the present invention includes the following steps:

[0010] (1) Prepare a surfactant solution. At 50 - 80 °C, add the KMnO4 solution to the surfactant solution to obtain a mixed solution;

[0011] (2) Crush the biomass, disperse it in water, add it to the mixed solution in step (1), adjust the pH value to 6 - 9, stir and react at 20 - 60 °C. After the reaction, filter, wash and dry the solid to obtain the biomass@MnO2 functional material.

[0012] As a further preference for the preparation method of the functional material for removing complex heavy metals, the surfactant in step (1) is an ionic surfactant, such as at least one of cetyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, etc., and the concentration of the surfactant solution is 0.05 - 0.2 mol / L.

[0013] As a preparation method of a functional material for removing complex heavy metals, further preferably, the 50 - 80 °C in step (1) is preferably carried out under the condition of water bath temperature control.

[0014] As a preparation method of a functional material for removing complex heavy metals, further preferably, the mass fraction of the KMnO4 solution in step (1) is 3% - 6%.

[0015] As a preparation method of a functional material for removing complex heavy metals, further preferably, the volume ratio of the surfactant solution to the KMnO4 solution in step (1) is 1:1 - 1:2.

[0016] As a preparation method of a functional material for removing complex heavy metals, further preferably, the biomass in step (2) is selected from one or several mixtures of wood waste, crop waste, etc., preferably one or several mixtures of corn silk, corn straw, corn leaves, pine wood, poplar bark, phoenix tree leaves, apple tree branches, etc. The biomass is pulverized to pass through a 10 - mesh sieve.

[0017] As a preparation method of a functional material for removing complex heavy metals, further preferably, the mass ratio of the biomass to water in step (2) is (0.01 - 0.1):1. After dispersing the biomass in water, it is added to the mixture in step (1) at a speed of 0.5 - 1.0 mL / min.

[0018] As a preparation method of a functional material for removing complex heavy metals, further preferably, the mass ratio of the biomass to KMnO4 in step (2) is controlled to be 1:(0.5 - 3).

[0019] As a preparation method of a functional material for removing complex heavy metals, further preferably, the stirring reaction in step (2) at 20 - 60 °C is preferably carried out under the condition of water bath temperature control. The stirring speed is 300 - 600 rpm, and the reaction time is 0.5 - 6 h.

[0020] As a preparation method of a functional material for removing complex heavy metals, further preferably, the filtration in step (2) is carried out by means of pressure filtration, etc., and washed to neutral; the drying is carried out by heat drying or freeze drying, the heat drying temperature is 60 - 100 °C, and the freeze drying temperature is -20 ~ -40 °C.

[0021] The functional material for removing complex heavy metals described in the present invention is prepared by the above - described method of the present invention. In the prepared biomass@MnO2 functional material, the proportion of biomass is 35% - 75%, the proportion of manganese oxide is 25% - 65%, and the content of manganese dioxide accounts for more than 80% of the manganese oxide.

[0022] The present invention also provides a method for removing complex heavy metal ions in wastewater by using the above functional material. The biomass@MnO2 functional material is added to the wastewater containing complex heavy metal ions, and an oxidant is added for reaction.

[0023] As a further preferred method for removing complex heavy metal ions in wastewater by the biomass@MnO2 functional material, the complex heavy metal ions are mainly complex heavy metal ions combined with heavy metal ions such as ethylenediaminetetraacetic acid (EDTA) or cyanide (CN) that have no reducibility or weak reducibility. Specifically, it can be [Cu(CN)4] 2- , [Cu(EDTA)] 2- , [Ni(CN)4] 2- , [Zn(CN)4] 2- , [Ni(EDTA)] 2- , [Zn(EDTA)] 2- and at least one of the like.

[0024] As a further preferred method for removing complex heavy metal ions in wastewater by the biomass@MnO2 functional material, the dosage of the biomass@MnO2 functional material is 0.8 - 1.6 g / L.

[0025] As a further preferred method for removing complex heavy metal ions in wastewater by the biomass@MnO2 functional material, the oxidant can be at least one of ozone, hydrogen peroxide, persulfate, etc. When using ozone, the ozone dosage is 20 - 100 mg / L, and the ozone introduction time is 20 - 120 min. When using hydrogen peroxide, the hydrogen peroxide dosage is 50 - 300 g / L (measured by 30% hydrogen peroxide solution). When using persulfate, the persulfate dosage is 2 - 10 mmol / L.

[0026] As a further preferred method for removing complex heavy metal ions in wastewater by the biomass@MnO2 functional material, the reaction stirring speed is 200 - 600 rpm, and the stirring time is 0.5 - 6 h.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] (1) In the prior art, biomass is generally carbonized into biochar to improve its adsorption performance, and its use performance is improved by means of oxidation modification and the like. In the process of research, the inventors of the present application found that when used for removing complex heavy metal ions such as CN or EDTA in wastewater, the surface of the biochar obtained by pyrolysis contains a large number of basic groups, so that its surface shows high negative charge, while complex heavy metal ions usually also carry negative charges. The electrostatic repulsion between the biochar and the complex heavy metal ions is not conducive to the contact and interaction between the material and the pollutants. Therefore, according to the characteristics of biomass, the inventors directly use uncarbonized biomass as the substrate material, and combine with a specific preparation method to in-situ control the generation of reduction products mainly composed of MnO2 on the surface of the biomass, thereby preparing a biomass@MnO2 functional material for removing complex heavy metal ions.

[0029] (2) An ionic surfactant is mixed with KMnO4 under certain conditions and used for biomass modification. This can not only make the manganese oxide mainly in the form of MnO2, but also enhance the binding force between the two and avoid the loss of MnO2.

[0030] (3) The functional material of the present invention can be prepared by a low-temperature solution method, without high-temperature roasting. The raw materials are easy to obtain, and the preparation method is simple, energy-saving and environmentally friendly.

[0031] (4) When the biomass@MnO2 material is used for removing non-reducing or weakly reducing complex heavy metal ions such as EDTA or cyanide in wastewater, the synergistic catalytic oxidation activity and synergistic adsorption characteristics of the material can be utilized to simultaneously achieve the pre-breaking of the complexation and the efficient removal of the complex heavy metal ions. Description of the Drawings

[0032] Figure 1 is the X-ray photoelectron spectroscopy diagram of the Mn element in the functional material prepared in Example 1. Detailed Embodiments

[0033] The following specific examples are used to further illustrate the functional material for removing complex heavy metal ions of the present invention and its effects. The examples are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given, but the protection scope of the present invention is not limited to the following examples.

[0034] The experimental methods in the following examples are all conventional methods in the art unless otherwise specified. The experimental materials used in the following examples are all purchased from conventional biochemical reagent stores unless otherwise specified.

[0035] The metal ion content in the present invention was determined by an inductively coupled plasma spectrometer (iCAP 6300, Thermo Scientific). The X-ray photoelectron spectroscopy of the corn silk @MnO2 material was measured by an X-ray photoelectron spectrometer (ESCALAB250Xi, Thermo Fisher Scientific).

[0036] Example 1

[0037] (1) Preparation of corn silk @MnO2 functional material

[0038] Prepare 0.1 mol / L cetyltrimethylammonium bromide solution and 3% (mass fraction) KMnO4 solution respectively. Under a 60 °C water bath, add 10 mL of KMnO4 solution dropwise to 10 mL of surfactant solution to obtain a mixed solution.

[0039] Put the corn silk into a high-speed grinder and crush it to pass through a 10-mesh sieve. Take 0.1 g and add it to a 100 mL beaker, disperse it in 10 mL of water, add it to the mixed solution at a rate of 0.5 mL / min, adjust the pH value of the mixed solution to 7, place it in a 40 °C water bath, and stir and react at 300 rpm for 6 h. After the reaction is completed, separate the solid by filtration, wash it 3 times with pure water, and place it in a 60 °C blast drying oven to dry to constant weight, thus obtaining the corn silk @MnO2 functional material. In the prepared material, the biomass content is 35.2% and the MnO2 content is 54.8%.

[0040] Appendix Figure 1 is the X-ray photoelectron spectroscopy diagram of the Mn element in the corn silk @MnO2 functional material. It can be seen from the attached figure that in the prepared material, the surface of the modified corn silk is loaded with a reduction product mainly composed of MnO2.

[0041] (2) Application of the corn silk @MnO2 material in the removal of complex heavy metal ions

[0042] Take a solution containing 50 ppm [Cu(CN)4] 2- ions, add the corn silk @MnO2 material at a dosage of 0.8 g / L, turn on the ozone generator for aeration, control the ozone concentration at 50 mg / L, and continue aeration for 60 min. After stopping aeration, continue to stir at 500 rpm for 2 h. The removal rate of [Cu(CN)4] 2- measured by an inductively coupled plasma spectrometer is 98%.

[0043] Comparative experiment 1: Replace the corn silk @MnO2 material with an equal amount of corn silk, keep other experimental parameters exactly the same, and there is no removal of [Cu(CN)4] 2- .

[0044] Comparative experiment 2, without ozone exposure, with all other experimental parameters being exactly the same, [Cu(CN)4] 2- There was no removal.

[0045] Comparative experiment 3, using an equal amount of corn silk + commercially available natural manganese sand (with an MnO2 content of approximately 40%) to replace the corn silk@MnO2 material (the ratio of corn silk to MnO2 in both is the same), with all other experimental parameters being exactly the same, [Cu(CN)4] 2- The removal rate was 5%.

[0046] Comparative experiment 4, using an equal amount of KMnO4 - oxidized modified corn silk (without MnO2 loading on the surface) + commercially available natural manganese sand (with an MnO2 content of approximately 40%) to replace the corn silk@MnO2 material (the ratio of corn silk to MnO2 in both is the same), with all other experimental parameters being exactly the same, [Cu(CN)4] 2- The removal rate was 84%.

[0047] Comparative experiment 5, using an equal amount of manganese dioxide loaded on biomass carbon to replace the corn silk@MnO2 material, with all other experimental parameters being exactly the same, [Cu(CN)4] 2- The removal rate was 76%.

[0048] Comparative experiment 6, using the nano - manganese - oxide - modified biomass carbon prepared in Example 1 of CN201910939573.3 to remove [Cu(CN)4] 2- , with all other experimental parameters being exactly the same, and the removal rate was 85%.

[0049] Example 2

[0050] (1) Preparation of corn straw@MnO2 functional material

[0051] Prepare 0.1 mol / L sodium dodecylbenzenesulfonate solution and 5% (mass fraction) KMnO4 solution respectively. Under a 50 °C water bath, add 10 mL of KMnO4 solution dropwise to 10 mL of surfactant solution to obtain a mixed solution;

[0052] Put the corn straw into a high - speed crusher and crush it to pass through a 10 - mesh sieve. Take 1 g and add it to a 100 mL beaker, disperse it in 10 mL of water, add it to the mixed solution at a rate of 1 mL / min, adjust the pH of the mixed solution to 6, place it in a 20 °C water bath, and stir and react at 400 rpm for 2 h. After the reaction is completed, separate the reaction product by filtration, wash it 3 times with pure water, and place it in a 60 °C blast drying oven to dry to constant weight, thus obtaining the corn straw@MnO2 functional material. In the prepared material, the biomass content is 74.3% and the MnO2 content is 20.6%.

[0053] (2)Using corn straw@MnO2 material for the removal of complex heavy metal ions

[0054] Take a solution containing 50 ppm [Cu(EDTA)] 2- ions, add corn straw@MnO2 material at a dosage of 1.6 g / L, turn on the ozone generator for aeration, control the ozone concentration at 20 mg / L, and continuously aerate for 120 min. After stopping aeration, continue to stir at 200 rpm for 6 h. The removal rate of [Cu(EDTA)] 2- is measured to be 99% by means of an inductively coupled plasma spectrometer.

[0055] In Comparative Experiment 1, an equal amount of corn straw is used to replace the corn straw@MnO2 material, and other experimental parameters are exactly the same. [Cu(EDTA)] 2- has basically no removal.

[0056] In Comparative Experiment 2, without ozone aeration, other experimental parameters are exactly the same. [Cu(EDTA)] 2- has basically no removal.

[0057] In Comparative Experiment 3, an equal amount of corn straw + commercially available natural manganese sand (with an MnO2 content of about 40%) is used to replace the corn straw@MnO2 material. The contents of corn straw and MnO2 are the same as those of the corn straw@MnO2 material, and other experimental parameters are exactly the same. The removal rate of [Cu(EDTA)] 2- is 9%.

[0058] In Comparative Experiment 4, an equal amount of KMnO4-oxidized modified corn straw (controlling no MnO2 loading on the surface) + commercially available natural manganese sand (with an MnO2 content of about 40%) is used to replace the corn straw@MnO2 material. The contents of oxidized modified corn straw and MnO2 are the same as those of the corn straw@MnO2 material, and other experimental parameters are exactly the same. The removal rate of [Cu(EDTA)] 2- is 85%.

[0059] In Comparative Experiment 5, an equal amount of biomass carbon loaded with an equal amount of manganese dioxide is used to replace the corn straw@MnO2 material, and other experimental parameters are exactly the same. The removal rate of [Cu(EDTA)] 2- is 75%.

[0060] In Comparative Experiment 6, the nano-manganese oxide modified biomass carbon prepared in Example 1 of CN201910939573.3 is used to remove [Cu(EDTA)] 2- , and other experimental parameters are exactly the same. The removal rate is 86%.

[0061] Example 3

[0062] (1)Preparation of Corn Leaf - Corn Silk @MnO₂ Functional Material

[0063] Prepare 0.05 mol / L cetyltrimethylammonium bromide solution and 6% (mass fraction) KMnO₄ solution respectively. Under a 60 °C water bath, add 10 mL of KMnO₄ solution dropwise to 10 mL of surfactant solution to obtain a mixed solution.

[0064] Put corn leaves and corn silk into a high - speed grinder and crush them to pass through a 10 - mesh sieve. Take 0.15 g of corn leaves and 0.15 g of corn silk and add them to a 100 mL beaker, disperse them in 10 mL of water, add them to the mixed solution at a rate of 0.5 mL / min, adjust the pH value of the mixed solution to 9, place it in a 60 °C water bath, and stir and react at 600 rpm for 0.5 h. After the reaction is completed, separate the reaction product by filtration, wash it 3 times with pure water, and place it in a freeze - drying oven to dry to constant weight, then the corn leaf - corn silk @MnO₂ functional material is obtained. In the prepared material, the biomass content is 46.8% and the MnO₂ content is 42.6%.

[0065] (2)Using Corn Leaf - Corn Silk @MnO₂ Material for the Removal of Complex Heavy Metal Ions

[0066] Take a solution containing 50 ppm [Ni(CN)₄] 2- ions, add the corn leaf - corn silk @MnO₂ material at a dosage of 0.8 g / L, turn on the ozone generator for aeration, control the ozone concentration at 100 mg / L, and continuously aerate for 20 min. After stopping aeration, continue to stir and adsorb at 600 rpm for 0.5 h. With the help of an inductively coupled plasma spectrometer, the removal rate of [Ni(CN)₄] 2- is 97%.

[0067] In Comparative Experiment 1, replace the corn leaf - corn silk @MnO₂ material with an equal amount of corn leaves and corn silk (mass ratio 1:1), and keep other experimental parameters exactly the same. [Ni(CN)₄] 2- has basically no removal.

[0068] In Comparative Experiment 2, without ozone aeration and keeping other experimental parameters exactly the same, [Ni(CN)₄] 2- has basically no removal.

[0069] In Comparative Experiment 3, replace the corn leaf - corn silk @MnO₂ material with an equal amount of corn leaves and corn silk (mass ratio 1:1) + commercially available natural manganese sand (MnO₂ content is about 40%), the contents of corn leaves - corn silk and MnO₂ are the same as those in the corn leaf - corn silk @MnO₂ material, and keep other experimental parameters exactly the same. The removal rate of [Ni(CN)₄] 2- is 9%.

[0070] Comparative experiment 4: Use equal amounts of KMnO4 to oxidize and modify corn leaves - corn whiskers (control no MnO2 loading on the surface) + commercially available natural manganese sand (MnO2 content is about 40%) to replace the corn leaves - corn whiskers@MnO2 material. The content of oxidized and modified corn leaves - corn whiskers and MnO2 is the same as that of the corn leaves - corn whiskers@MnO2 material, and other experimental parameters are exactly the same. [Ni(CN)4] 2- The removal rate is 79%.

[0071] Comparative experiment 5: Use equal amounts of biomass carbon loaded with equal amounts of manganese dioxide to replace the corn leaves - corn whiskers@MnO2 material, and other experimental parameters are exactly the same. [Ni(CN)4] 2- The removal rate is 80%.

[0072] Comparative experiment 6: Use the nano - manganese oxide - modified biomass carbon prepared in Example 1 of CN201910939573.3 to remove [Ni(CN)4] 2- , and other experimental parameters are exactly the same. The removal rate is 82%.

[0073] Example 4

[0074] (1) Preparation of pine@MnO2 functional material

[0075] Prepare 0.1mol / L cetyltrimethylammonium bromide solution and 3% (mass fraction) KMnO4 solution respectively. Under a 70°C water bath, add 10 mL of KMnO4 solution dropwise to 10 mL of surfactant solution to obtain a mixed solution;

[0076] Put pine into a high - speed crusher and crush it to pass through a 10 - mesh sieve. Take 0.1 g and add it to a 100 - mL beaker, disperse it in 10 mL of water, add it to the mixed solution at a rate of 0.5 mL / min, adjust the pH of the mixed solution to 7, place it in a 40°C water bath, and stir and react for 6 h under the condition of 300 rpm. After the reaction is completed, separate the reaction product by filtration, wash it 3 times with pure water, and place it in a 60°C blast drying oven to dry to a constant weight, then obtain the pine@MnO2 functional material. In the prepared material, the biomass content is 36.7% and the MnO2 content is 53.6%.

[0077] (2) Use the pine@MnO2 material for the removal of complex heavy metal ions

[0078] Take a solution containing 50 ppm [Zn(CN)4] 2-A solution of ions, add pine@MnO2 material at a dosage of 0.8 g / L, turn on the ozone generator for aeration, control the ozone concentration at 50 mg / L, and continuously aerate for 1 h. After stopping aeration, continue to stir and adsorb at 500 rpm for 2 h. Measured by inductively coupled plasma spectrometer, the removal rate of [[Zn(CN)4]] 2- is 98%.

[0079] For Comparative Experiment 1, replace the pine@MnO2 material with an equal amount of pine, and keep other experimental parameters exactly the same. For [[Zn(CN)4]] 2- there is basically no removal.

[0080] For Comparative Experiment 2, without ozone aeration, keep other experimental parameters exactly the same. For [[Zn(CN)4]] 2- there is basically no removal.

[0081] For Comparative Experiment 3, replace the pine@MnO2 material with an equal amount of pine + commercially available natural manganese sand (MnO2 content is about 40%), the contents of pine and MnO2 are the same as those of the pine@MnO2 material, and keep other experimental parameters exactly the same. For [[Zn(CN)4]] 2- the removal rate is 8%.

[0082] For Comparative Experiment 4, replace the pine@MnO2 material with KMnO4-oxidized pine (control no MnO2 loading on the surface) + commercially available natural manganese sand (MnO2 content is about 40%), the contents of oxidized pine and MnO2 are the same as those of the pine@MnO2 material, and keep other experimental parameters exactly the same. For [[Zn(CN)4]] 2- the removal rate is 87%.

[0083] For Comparative Experiment 5, replace the pine@MnO2 material with an equal amount of biomass carbon loaded with an equal amount of manganese dioxide, and keep other experimental parameters exactly the same. For [[Zn(CN)4]] 2- the removal rate is 80%.

[0084] For Comparative Experiment 6, use the nano-manganese oxide modified biomass carbon prepared in Example 1 of CN201910939573.3 to remove [[Zn(CN)4]] 2- , keep other experimental parameters exactly the same, and the removal rate is 83%.

[0085] Example 5

[0086] (1) Preparation of poplar bark@MnO2 functional material

[0087] Prepare 0.2 mol / L sodium dodecylbenzenesulfonate solution and 5% (mass fraction) KMnO4 solution respectively. Under an 80 °C water bath, drop 5 mL of KMnO4 solution into 10 mL of surfactant solution to obtain a mixed solution;

[0088] Put the poplar bark into a high-speed crusher and crush it to pass through a 10-mesh sieve. Take 1 g and add it to a 100 mL beaker, disperse it in 10 mL of water, add it to the mixed solution at a rate of 0.75 mL / min, adjust the pH value of the mixed solution to 8, place it in a 20 °C water bath, and stir and react at 400 rpm for 2 h. After the reaction is completed, separate the reaction product by filtration, wash it 3 times with pure water, place it in a blast drying oven at 60 °C, and dry it to a constant weight to obtain the poplar bark@MnO2 functional material. In the prepared material, the biomass content is 74.9% and the MnO2 content is 22%.

[0089] (2) Use the poplar bark@MnO2 material for the removal of complex heavy metal ions

[0090] Take a solution containing 50 ppm [Ni(EDTA)] 2- ions, add the poplar bark@MnO2 material at a dosage of 1.2 g / L, turn on the ozone generator for aeration, control the ozone concentration to be 20 mg / L, and continuously aerate for 120 min. After stopping aeration, continue to stir and adsorb at 200 rpm for 6 h. The removal rate of [Ni(EDTA)] 2- is measured to be 96% by means of an inductively coupled plasma spectrometer.

[0091] In Comparative Experiment 1, replace the poplar bark@MnO2 material with an equal amount of poplar bark, and keep other experimental parameters exactly the same. [Ni(EDTA)] 2- is hardly removed.

[0092] In Comparative Experiment 2, without ozone aeration, keep other experimental parameters exactly the same. [Ni(EDTA)] 2- is hardly removed.

[0093] In Comparative Experiment 3, replace the poplar bark@MnO2 material with an equal amount of poplar bark + commercially available natural manganese sand (MnO2 content is about 40%), the contents of poplar bark and MnO2 are the same as those of the poplar bark@MnO2 material, and keep other experimental parameters exactly the same. The removal rate of [Ni(EDTA)] 2- is 6%.

[0094] In Comparative Experiment 4, replace the poplar bark@MnO2 material with an equal amount of KMnO4-oxidized modified poplar bark (control no MnO2 loading on the surface) + commercially available natural manganese sand (MnO2 content is about 40%), the contents of oxidized modified poplar bark and MnO2 are the same as those of the poplar bark@MnO2 material, and keep other experimental parameters exactly the same. The removal rate of [Ni(EDTA)] 2- is 77%.

[0095] Comparative experiment 5: Equal amounts of manganese dioxide were loaded on equal amounts of biomass charcoal to replace the poplar bark@MnO2 material, and other experimental parameters were exactly the same. [Ni(EDTA)] 2- The removal rate was 73%.

[0096] Comparative experiment 6: The nano-manganese oxide modified biomass charcoal prepared in Example 1 of CN201910939573.3 was used to remove [Ni(EDTA)] 2- with other experimental parameters being exactly the same, and the removal rate was 80%.

[0097] Example 6

[0098] (1) Preparation of the sycamore leaf - apple branch@MnO2 material

[0099] Prepare 0.05 mol / L sodium dodecylbenzenesulfonate solution and 6% (mass fraction) KMnO4 solution respectively. Under a 60°C water bath, add 10 mL of KMnO4 solution dropwise to 10 mL of surfactant solution to obtain a mixed solution;

[0100] Put sycamore leaves and apple branches into a high-speed grinder and crush them to pass through a 10-mesh sieve. Take 0.15 g of apple branches and 0.15 g of apple branches and add them to a 100 mL beaker, disperse them in 10 mL of water, add them to the mixed solution at a rate of 0.5 mL / min, adjust the pH value of the solution to 7, place it in a 60°C water bath, and stir and react at 600 rpm for 0.5 h. After the reaction is completed, separate the reaction product by filtration, wash it 3 times with pure water, and place it in a freeze-drying oven to dry to constant weight, then the sycamore leaf - apple branch@MnO2 material is obtained. In the prepared material, the biomass content is 45.8% and the MnO2 content is 43.4%.

[0101] (2) Use of the sycamore leaf - apple branch@MnO2 material for the removal of complex heavy metal ions

[0102] Take a solution containing 50 ppm [Zn(EDTA)] 2- ions, add the sycamore leaf - apple branch@MnO2 material at a dosage of 1.2 g / L, turn on the ozone generator for aeration, control the ozone concentration at 100 mg / L, and continuously aerate for 20 min. After stopping aeration, continue to stir and adsorb at 600 rpm for 0.5 h. The removal rate of [Zn(EDTA)] 2- was measured to be 90% by means of an inductively coupled plasma spectrometer.

[0103] Comparative experiment 1: Equal amounts of sycamore leaves and apple branches (mass ratio 1:1) were used to replace the sycamore leaf - apple branch@MnO2 material, and other experimental parameters were exactly the same. [Zn(EDTA)] 2- showed basically no removal.

[0104] Comparative experiment 2, without ozone exposure, with all other experimental parameters being exactly the same, [Zn(EDTA)] 2- There is basically no removal.

[0105] Comparative experiment 3, using an equal amount of plane tree leaves and apple tree branches (mass ratio 1:1) + commercially available natural manganese sand (MnO2 content is about 40%) to replace the plane tree leaf - apple tree branch @MnO2 material, with the content of biomass and MnO2 being the same as that of the plane tree leaf - apple tree branch @MnO2 material, and all other experimental parameters being exactly the same, [Zn(EDTA)] 2- The removal rate is 13%.

[0106] Comparative experiment 4, using an equal amount of KMnO4 - oxidized modified plane tree leaves - apple tree branches (mass ratio 1:1, controlling no MnO2 loading on the surface) + commercially available natural manganese sand (MnO2 content is about 40%) to replace the plane tree leaf - apple tree branch @MnO2 material, with the content of the oxidized modified plane tree leaves - apple tree branches and MnO2 being the same as that of the plane tree leaf - apple tree branch @MnO2 material, and all other experimental parameters being exactly the same, [Zn(EDTA)] 2- The removal rate is 85%.

[0107] Comparative experiment 5, using an equal amount of manganese dioxide loaded on biomass carbon to replace the plane tree leaf - apple tree branch @MnO2 material, with all other experimental parameters being exactly the same, [Zn(EDTA)] 2- The removal rate is 79%.

[0108] Comparative experiment 6, using the nano - manganese oxide - modified biomass carbon prepared in Example 1 of CN201910939573.3 to remove [Zn(EDTA)] 2- , with all other experimental parameters being exactly the same, and the removal rate is 81%.

[0109] Example 7

[0110] Using the corn silk @MnO2 functional material prepared in Example 1 to remove complex heavy metal ions in wastewater. The concentration of complex heavy metal ions in the wastewater is 50 ppm. Add the corn silk @MnO2 material at 0.8 g / L. Use ozone, hydrogen peroxide, and potassium peroxymonosulfate as oxidants respectively, control the dosage of the oxidant, and stir and react for 6 h under the condition of 500 rpm. Measure the residual concentration of the ions with an inductively coupled plasma spectrometer and calculate the ion removal rate. The results are shown in Table 1.

[0111] Table 1

[0112]

[0113] Comparative example 1

[0114] Same as Example 1, except that: during the material preparation process, Tween 80 surfactant was used instead of cetyltrimethylammonium bromide to prepare the functional material. Under the condition that other experimental parameters are exactly the same, 2- the removal rate of [[Cu(CN)4]] is 83%.

[0115] Comparative Example 2

[0116] Same as Example 1, except that: during the material preparation process, the KMnO4 solution was added dropwise to the surfactant solution at 35°C to prepare the functional material. Other experimental parameters are exactly the same, 2- the removal rate of [[Cu(CN)4]] is 85%.

[0117] Comparative Example 3

[0118] Same as Example 1, except that: during the material preparation process, MnO2 was used instead of KMnO4 to prepare the functional material. Other experimental parameters are exactly the same, 2- the removal rate of [[Cu(CN)4]] is 5%.

[0119] Comparative Example 4

[0120] Same as Example 1, except that: during the material preparation process, the KMnO4 solution and the surfactant solution were directly mixed without dropwise addition to prepare the functional material. Other experimental parameters are exactly the same, 2- the removal rate of [[Cu(CN)4]] is 73%.

[0121] Comparative Example 5

[0122] Same as Example 1, except that: during the material preparation process, the biomass was not dispersed in water and was directly added to the mixture in step (1) to prepare the functional material. Other experimental parameters are exactly the same, 2- the removal rate of [[Cu(CN)4]] is 76%.

[0123] Comparative Example 6

[0124] Same as Example 1, except that: during the material preparation process, after adding the biomass to the mixture in step (1), the pH was adjusted to 5 or 10 to prepare the functional material. Other experimental parameters are exactly the same, 2- the removal rates of [[Cu(CN)4]] are 58% and 42%.

Claims

1. A preparation method of a functional material for removing complex heavy metals, characterized in that, It includes the following steps: (1) Prepare a surfactant solution. At 50 - 80 °C, add the KMnO4 solution to the surfactant solution to obtain a mixed solution. The surfactant is at least one of cetyltrimethylammonium bromide and sodium dodecylbenzenesulfonate. The concentration of the surfactant solution is 0.05 - 0.2 mol / L; the mass fraction of the KMnO4 solution is 3% - 6%; the volume ratio of the surfactant solution to the KMnO4 solution is 1:1 - 1:2; (2) Crush the biomass, disperse it in water, and add it to the mixed solution in step (1). Control the mass ratio of the biomass to KMnO4 to be 1:(0.5 - 3), adjust the pH value to 6 - 9, stir and react at 20 - 60 °C. After the reaction, filter, wash and dry the solid to obtain the biomass@MnO2 functional material; An ionic surfactant is mixed with KMnO4 and used for biomass modification, so that the manganese oxide is mainly in the form of MnO2, while enhancing the binding force between the biomass and MnO2 and avoiding the loss of MnO2.

2. The method according to claim 1, characterized in that: The 50 - 80 °C in step (1) is carried out under the condition of water bath temperature control.

3. The method according to claim 1, wherein: The biomass in step (2) is selected from one or several mixtures of corn silk, corn straw, corn leaves, pine wood, poplar bark, phoenix tree leaves, apple branches, etc.; the biomass is crushed to pass through a 10 - mesh sieve.

4. The method according to claim 1 or 3, characterized in that: The mass ratio of the biomass to water in step (2) is (0.01 - 0.1):1; after dispersing the biomass in water, add it to the mixed solution in step (1) at a speed of 0.5 - 1.0 mL / min.

5. The method according to claim 1, wherein: The stirring reaction at 20 - 60 °C in step (2) is carried out under the condition of water bath temperature control; the stirring speed is 300 - 600 rpm, and the reaction time is 0.5 - 6 h.

6. The method according to claim 1, characterized in that: The filtration in step (2) adopts the pressure filtration method and is washed to neutral; the drying adopts heating drying or freeze drying. The heating drying temperature is 60 - 100 °C, and the freeze drying temperature is -20 ~ -40 °C.

7. A functional material for removing complex heavy metals, characterized in that, The functional material is prepared by the method described in any one of claims 1 - 6.

8. The functional material according to claim 7, wherein: In the prepared biomass@MnO2 functional material, the proportion of the biomass is 35% - 75%, and the proportion of the manganese oxide is 25% - 65%, among which the content of manganese dioxide accounts for more than 80% of the manganese oxide.

9. A method for removing complex heavy metal ions in wastewater by using a functional material prepared by the method according to any one of claims 1-6, characterized in that: Add the biomass@MnO2 functional material to the wastewater containing complex heavy metal ions, and add an oxidant to react.

10. The method according to claim 9, wherein: The complex heavy metal ions are [Cu(CN)4] 2- , [Cu(EDTA)] 2- , [Ni(CN)4] 2- , [Zn(CN)4] 2- , [Ni(EDTA)] 2- , [Zn(EDTA)] 2- or at least one of them.

11. The method according to claim 9, wherein: The dosage of the biomass@MnO2 functional material is 0.8 - 1.6 g / L.

12. The method according to claim 9, wherein: The oxidant is at least one of ozone, hydrogen peroxide, and persulfate.

13. The method according to claim 9, characterized in that: The stirring speed of the reaction is 200 - 600 rpm, and the reaction time is 0.5 - 6 h.

Images