CN109317100B - Normal-temperature pretreatment-hydrothermal carbonization method for preparing magnetic algae-based biochar - Google Patents

Normal-temperature pretreatment-hydrothermal carbonization method for preparing magnetic algae-based biochar Download PDF

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CN109317100B
CN109317100B CN201811373068.9A CN201811373068A CN109317100B CN 109317100 B CN109317100 B CN 109317100B CN 201811373068 A CN201811373068 A CN 201811373068A CN 109317100 B CN109317100 B CN 109317100B
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algae
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based biochar
water
temperature
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CN109317100A (en
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万俊力
丁健
孙士权
谭万春
聂小保
雷超
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Changsha University of Science and Technology
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    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/20—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising free carbon; comprising carbon obtained by carbonising processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28002—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their physical properties
    • B01J20/28009—Magnetic properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/74—Iron group metals
    • B01J23/745—Iron
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • C02F1/283—Treatment of water, waste water, or sewage by sorption using coal, charred products, or inorganic mixtures containing them
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/72—Treatment of water, waste water, or sewage by oxidation
    • C02F1/722—Oxidation by peroxides
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/72—Treatment of water, waste water, or sewage by oxidation
    • C02F1/725—Treatment of water, waste water, or sewage by oxidation by catalytic oxidation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2220/00—Aspects relating to sorbent materials
    • B01J2220/40—Aspects relating to the composition of sorbent or filter aid materials
    • B01J2220/48—Sorbents characterised by the starting material used for their preparation
    • B01J2220/4875—Sorbents characterised by the starting material used for their preparation the starting material being a waste, residue or of undefined composition
    • B01J2220/4887—Residues, wastes, e.g. garbage, municipal or industrial sludges, compost, animal manure; fly-ashes
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/20—Heavy metals or heavy metal compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/30—Organic compounds

Abstract

The invention discloses a normal-temperature pretreatment-hydrothermal carbonization method for preparing magnetic algae-based biochar, which comprises the steps of adding ferric salt and alkali into algae sludge, stirring, and carrying out magnetic separation to obtain dark green floc A; and then carrying out hydrothermal reaction on the dark green floc A to obtain a brownish black product B, and washing, carrying out solid magnetic separation and drying to obtain the magnetic algae-based biochar. The method disclosed by the invention does not need drying pretreatment, can efficiently treat high-concentration algae-rich water and algae mud/algae residue with high water content, is mild in reaction condition, simple to operate and environment-friendly, does not produce secondary pollution in the preparation process, and is an algae resource utilization method which accords with the low-carbon concept.

Description

Normal-temperature pretreatment-hydrothermal carbonization method for preparing magnetic algae-based biochar
Technical Field
The invention relates to the field of water treatment and biological environment-friendly materials, in particular to a normal-temperature pretreatment-hydrothermal carbonization method for preparing magnetic algae-based biochar.
Background
In recent years, the problem that water quality is deteriorated due to mass propagation of floating algae caused by eutrophication of water has attracted attention, and the treatment means such as salvaging, filtration, coagulating sedimentation, coagulating floatation and the like, which are adopted to cope with algal outbreaks, have brought another hot point problem of how to treat algal sludge with high pollution and high water content. At present, the treatment modes of algae mud, algae residues or high-concentration algae-rich water mainly comprise biodiesel preparation, coal slurry preparation, fertilizer or feed preparation, anaerobic fermentation, hydrothermal chemical product, fuel cells and the like, but the treatment modes are not applied or industrialized on a large scale, and have the defects of high cost, high energy consumption of dehydration pretreatment, difficulty in dehydration, complex steps, high equipment requirement, residual algae toxins, large secondary pollution risk and the like, so that a new method for economically feasible algae resource utilization is inevitably explored.
Patent document (publication No. CN101891188A) discloses a method for preparing nano activated carbon spheres by using blue algae residues, the product can be applied to the fields of environmental protection, lubrication, heat dissipation additives and the like, the harm caused by the algae residues and algal toxins can be reduced in the preparation process, and the environment-friendly and efficient concept is met. However, the method needs to firstly dry the algae residues until the water content is 5-10%, then the algae residues are crushed into powder to be subjected to stagnation treatment and carbonization treatment, and the problem that the algae residues are high in water content and difficult to dehydrate is not thoroughly solved. The hydrothermal technology uses high-temperature and high-pressure water as a reaction medium to complete a chemical process, has the characteristics of no toxicity, no harm, no secondary pollution and the like, and takes the algae sludge as wet biomass, the water content is generally 95-97%, and the contained algae biomass can directly react without dehydration when being treated by the hydrothermal technology, so that the problem of high dehydration energy consumption of the algae sludge is solved. The existing hydrothermal treatment technology of algae biomass mainly comprises hydrothermal gasification and hydrothermal liquefaction, wherein the product is gas or biofuel, the gasification temperature is 400-800 ℃, and the liquefaction temperature is usually 250-450 ℃.
The invention aims to effectively combine the coagulation pretreatment of algae biomass with the hydrothermal carbonization technology, adopts environment-friendly ferric salt and ferrous salt as pretreatment coagulants, prepares the magnetic algae-based biochar with adsorption and catalysis performances by a one-step hydrothermal method, and solves the following problems: how to generate magnetic algae flocs under the condition of normal temperature; how to make the normal temperature pretreatment and the hydrothermal carbonization synergistic.
Disclosure of Invention
In order to solve the problems in the prior art, the invention aims to provide a normal-temperature pretreatment-hydrothermal carbonization method for preparing magnetic algae-based biochar, the method does not need drying pretreatment, can efficiently treat high-concentration algae-rich water and algae mud/algae residue with high water content, has mild reaction conditions, does not generate secondary pollution in the preparation process, is simple to operate, is green and environment-friendly, and is an algae resource utilization method which accords with the low-carbon concept.
In order to achieve the technical purpose, the technical scheme of the invention is as follows:
a normal temperature pretreatment-hydrothermal carbonization method for preparing magnetic algae-based biochar comprises the steps of adding ferric salt and alkali into algae sludge, stirring, and carrying out magnetic separation to obtain dark green flocs A; and then carrying out hydrothermal reaction on the dark green floc A to obtain a brownish black product B, and washing, carrying out solid magnetic separation and drying to obtain the magnetic algae-based biochar.
Preferably, the algae sludge comprises high-concentration algae-rich water, algae mud in a sedimentation tank of a water treatment plant, air-float algae residues, and artificially salvaged or mechanically removed algae residues, and the mass percentage of the water in the algae sludge is 95-99 wt%. The method selects the algae sludge with high water content as the carbon source, mainly adopts hydrothermal carbonization in aqueous solution without drying pretreatment, and is very favorable for the algae sludge which is not easy to dehydrate; secondly, various elements such as nitrogen, oxygen and the like in the algae biomass can be reserved through normal-temperature pretreatment and hydrothermal carbonization, and abundant oxygen-containing and nitrogen-containing functional groups are formed on the surface of the carbide, so that the method can be applied to various fields.
Preferably, the mass ratio of the iron ions in the iron salt to the dry algae mud is 1: 70-150. The added iron ion amount can ensure the magnetic induction intensity of the dark green floc A and the magnetic algae-based biochar finally prepared and can avoid magnetic FeOXThe nano-particle loading is too high to cause raw material waste.
Preferably, the ferric salt comprises ferrous salt and trivalent ferric salt, and the ferrous salt is ferrous sulfate and/or ferrous chloride; the ferric iron salt is ferric trichloride and/or ferric sulfate; the alkali is sodium hydroxide and/or potassium hydroxide.
Preferably, Fe2+、OH-、Fe3+The molar ratio of (1-1.5: 6-8: 1) and the adding sequence of Fe2+、OH-And Fe3 +. Fe in the invention2+、OH-、Fe3+The molar ratio and the adding sequence of the components are ensuredThe key point of generating the magnetic algae flocs under the normal temperature condition is that the algae flocs generated in the range lower than or higher than the molar ratio have no magnetic induction or weak magnetic induction intensity; meanwhile, the algal flocs generated by changing the adding sequence also have no magnetic induction or weak magnetic induction intensity, and the magnetic separation effect of the dark green flocs A and the brownish black product B is difficult to ensure.
More preferably, the ferric salt is added in the form of an aqueous solution, the concentration of the aqueous solution of ferrous salt and ferric salt is 0.05-0.5 mol/L, and the concentration of the aqueous solution of alkali is 0.5-1.0 mol/L.
Preferably, the stirring temperature is 25-35 ℃, the time is 20-30 min, and the rotating speed is 20-50 rpm.
Preferably, the temperature of the hydrothermal reaction is 150-250 ℃ and the time is 12-24 h.
The invention also provides application of the magnetic algae-based biochar in adsorption removal of heavy metal ions or total phosphorus in water.
Preferably, the magnetic algae-based biochar is added into raw water according to the using amount of 100-400 mg/L and stirred for 10-30 min, and then the magnetic algae-based biochar after adsorption reaction is separated by an external magnetic field, so that solid-liquid separation is completed.
The invention also provides application of the magnetic algae-based biochar in catalyzing hydrogen peroxide to degrade organic pollutants in water.
Preferably, the mass ratio of the magnetic algae-based biochar to hydrogen peroxide is controlled to be 1: 1-2, the magnetic algae-based biochar and the hydrogen peroxide are sequentially added into raw water, stirred for 30-60 min under the condition that the pH value is 5-7, then the magnetic algae-based biochar after catalytic reaction is separated out through an external magnetic field, solid-liquid separation is completed, and the magnetic algae-based biochar is dried at the temperature of 40-60 ℃ and then is recycled.
The invention adopts the synergistic effect of normal temperature pretreatment and hydrothermal carbonization: firstly, using algae sludge as carbon source and Fe2+And Fe3+As iron source by controlling Fe2+、OH-、Fe3+The molar ratio and the adding sequence of the magnetic algae flocs, and the mass ratio of the iron ions to the dry algae sludge generate the magnetic algae flocs with good algae-water separation effect under the normal temperature condition; then, the mild pretreatment conditions preserve the surface of the algal cellsThe structure is characterized in that the carbide is favorable for generating surface active functional groups and amorphous hydroxyl FeO generated in the coagulation processXThe particles are uniformly dispersed in the algae flocs, which is favorable for uniformly catalyzing the carbonization reaction of the algae biomass and simultaneously avoids amorphous hydroxyl FeOXSynthesis of ferromagnetic FeO from particles in the phase inversion ProcessXAgglomeration occurs when the nanoparticles are present; finally, the magnetic algae floc is subjected to one-step hydrothermal carbonization reaction to efficiently prepare the loaded crystalline FeOXNano-particle magnetic algae-based biochar.
The invention has the advantages and beneficial effects that:
1. the preparation energy consumption is low. Aiming at the problems of high dehydration and carbonization energy consumption and the like in the resource utilization of algae sludge, the invention generates magnetically separable magnetic algae flocs through normal-temperature pretreatment, reduces the water content of the algae sludge, and ensures that the algae biomass in the magnetic algae flocs is in Fe state2+And Fe3+Under the catalytic action of the catalyst, the reaction temperature of the hydrothermal carbonization of the algae sludge is reduced by nearly half, and simultaneously, FeO is enhanced under the high-temperature and high-pressure conditions of the hydrothermal carbonizationXThe invention achieves the purpose of reducing energy consumption through the synergistic effect of normal temperature pretreatment and hydrothermal carbonization.
2. The risk of secondary pollution is low. The invention adopts ferric salt coagulation to pretreat the algae sludge at normal temperature, does not destroy extracellular polymers of algae cells, avoids the release of substances inside and outside the algae cells, and is used for treating the algae sludge under the conditions of high temperature and high pressure of hydrothermal carbonization and Fe2+And Fe3+Under the catalytic action of the catalyst, the algal toxins are degraded and removed, so that the risk of secondary pollution to the environment is reduced, and the aim of harmless treatment of the algal sludge is fulfilled.
3. The application range is wide. The magnetic algae-based biochar prepared by the method disclosed by the invention can be applied to the fields of water environment restoration and water treatment, can quickly adsorb and remove heavy metal ions and total phosphorus in water, can also be used as a catalyst of an advanced oxidation technology, and can effectively catalyze hydrogen peroxide to degrade organic pollutants.
4. The cyclic utilization rate is high. The magnetic algae-based biochar prepared by the method has high stability, can be separated and recovered through an external magnetic field, is simple to operate, can be recycled for 5-10 times under the same condition, and has a good catalytic degradation effect.
Drawings
FIG. 1 is a photomicrograph of magnetic algal flocs obtained by room temperature pretreatment in example 1;
FIG. 2 is a scanning electron micrograph of the magnetic algal-based biochar prepared in example 1;
FIG. 3 is a transmission electron micrograph of magnetic algal-based biochar prepared according to example 1;
FIG. 4 is an infrared spectrum of a magnetic algal-based biochar prepared in example 1;
FIG. 5 shows the X-ray diffraction patterns of the magnetic algal flocs and magnetic algal-based biochar prepared in example 1.
Detailed Description
The present invention is further explained below with reference to examples.
Example 1
2.5m L ferrous sulfate (0.05 mol/L), 1.5m L sodium hydroxide (0.5 mol/L), 2.5m L ferric chloride (0.05 mol/L) solution (Fe)2+/OH-/Fe3+The mol ratio is 1: 6: 1), the materials are sequentially and rapidly added into 100m L cyanobacteria sludge with the water content of 97 percent, the mixture is stirred for 30min at the temperature of 30 ℃ and at the speed of 40rpm, the dark green floc A is subjected to hydrothermal reaction for 24h at the temperature of 150 ℃ and is naturally cooled to the room temperature, a brownish black product B is obtained, the brownish black product B is washed for 5 times by deionized water, the solid magnetic separation is carried out, the drying is carried out at the temperature of 60 ℃, and the grinding is carried out to 200-300 meshes, so that the magnetic algae-based biochar is obtained.
The magnetic algae-based biochar prepared in the embodiment is characterized and analyzed, and the detection results are shown in fig. 1 to 5: FIG. 1 is a photomicrograph of magnetic algal flocs obtained by room temperature pretreatment, from FIG. 1, it can be seen that cyanobacteria cells are wrapped in amorphous iron hydroxide flocs, and magnetic amorphous hydroxyl FeO is dispersed in the flocsXParticles; FIG. 2 is a scanning electron micrograph of the magnetic algae-based biochar obtained from the preparation, and FeO in the form of a bright spot is shown in FIG. 2XThe particles are dispersed in dark algae baseThe entire surface of the biochar; FIG. 3 is a transmission electron micrograph of the magnetic algal-based biochar prepared, from which FIG. 3 it can be seen that quasi-spherical and acicular particles are dispersed in a light-colored carbon layer; FIG. 4 is an infrared spectrum of the prepared magnetic algae-based biochar, and it can be seen from FIG. 4 that the magnetic algae-based biochar obtained by hydrothermal carbonization inherits abundant functional groups from a carbon source and an iron source; FIG. 5 is the X-ray diffraction spectrum of the magnetic algae flocs and the magnetic algae-based biochar, and it can be seen from FIG. 5 that the magnetic particles in the magnetic algae flocs are amorphous hydroxyl FeOXThe magnetic particles in the magnetic algae-based biochar obtained after hydrothermal carbonization are crystalline FeOX。
Example 2
2.5m L ferrous sulfate (0.05 mol/L), 1.5m L sodium hydroxide (0.5 mol/L), 2.5m L ferric chloride (0.05 mol/L) solution (Fe)2+/OH-/Fe3+The mol ratio is 1: 6: 1) are sequentially and rapidly added into 100m L chlorella algae residues with the water content of 97 percent, the mixture is stirred for 30min at the temperature of 30 ℃ and the rpm of 40, the dark green floc A is obtained by solid magnetic separation, the dark green floc A is subjected to hydrothermal reaction for 24h at the temperature of 150 ℃, the product is naturally cooled to the room temperature, a brownish black product B is obtained, and the steps of cleaning, drying and grinding in the example 1 are repeated, so that the magnetic algae-based charcoal is obtained.
Example 3
3.0m L ferrous sulfate (0.05 mol/L), 1.6m L sodium hydroxide (0.5 mol/L), 2.0m L ferric chloride (0.05 mol/L) solution (Fe)2+/OH-/Fe3+The molar ratio is 1.5: 8: 1) is sequentially and rapidly added into 100m L cyanobacteria sludge with the water content of 97 percent, the mixture is stirred for 30min at the temperature of 30 ℃ and at the speed of 40rpm, the dark green floc A is obtained by carrying out the solid magnetic separation, the dark green floc A is subjected to the hydrothermal reaction for 12h at the temperature of 200 ℃, the product B is obtained by naturally cooling to the room temperature, and the steps of cleaning, drying and grinding in the example 1 are repeated to obtain the magnetic algae-based biochar.
Example 4
3.0m L ferrous sulfate (0.05 mol/L), 1.6m L sodium hydroxide (0.5 mol/L), 2.0m L ferric chloride (0.05 mol/L) solution (Fe)2+/OH-/Fe3+The mol ratio is 1.5: 8: 1) is added into 100m L with the water content of 97 percentStirring the chlorella residue for 30min at 30 ℃ and 40rpm, and performing solid magnetic separation to obtain dark green floc A; carrying out hydrothermal reaction on the dark green floc A at 200 ℃ for 12h, and naturally cooling to room temperature to obtain a brownish black product B; the washing-drying-grinding steps in example 1 were repeated to obtain magnetic algal-based biochar.
Comparative example 1
2.0m L ferrous sulfate (0.05 mol/L), 1.35m L sodium hydroxide (0.5 mol/L), 2.5m L ferric chloride (0.05 mol/L) solution (Fe)2+/OH-/Fe3+The mol ratio is 0.8: 5.4: 1), the materials are sequentially and rapidly added into 100m L cyanobacteria sludge with the water content of 97 percent, the mixture is stirred for 30min at the temperature of 30 ℃ and 40rpm, the mixture is kept stand and then is subjected to centrifugal separation to obtain dark green floc A, the dark green floc A is subjected to hydrothermal reaction for 24h at the temperature of 150 ℃, the mixture is naturally cooled to the room temperature to obtain a brownish black product B, the brownish black product B is washed for 5 times by deionized water, the solid centrifugal separation is carried out, the product is dried at the temperature of 60 ℃, the product is ground to 200-300 meshes to obtain algae-based biochar, and the final product is free of magnetic induction through testing.
Comparative example 2
4.0m L ferrous sulfate (0.05 mol/L), 1.8m L sodium hydroxide (0.5 mol/L), 2.0m L ferric chloride (0.05 mol/L) solution (Fe)2+/OH-/Fe3+The mol ratio is 2: 9: 1) is sequentially and rapidly added into 100m L cyanobacteria sludge with the water content of 97 percent, the mixture is stirred for 30min at the temperature of 30 ℃ and at the speed of 40rpm, the mixture is kept stand and then is centrifugally separated, so that dark green floc A is obtained, the dark green floc A is subjected to hydrothermal reaction for 24h at the temperature of 150 ℃, the mixture is naturally cooled to the room temperature, so that a brownish black product B is obtained, the steps of cleaning, drying and grinding in the comparative example 1 are repeated, so that the algae-based biochar is obtained, and the final product is weak in magnetic induction.
Comparative example 3
2.5m L ferric chloride (0.05 mol/L), 1.5m L sodium hydroxide (0.5 mol/L), 2.5m L ferrous sulfate (0.05 mol/L) solution (Fe)3+/OH-/Fe2+The mol ratio is 1: 6: 1) is added into 100m L cyanobacteria sludge with the water content of 97 percent in sequence and rapidly, the mixture is stirred for 30min under the conditions of 30 ℃ and 40rpm, the mixture is kept stand and then is centrifugally separated to obtain blackish green flocs A, the blackish green flocs A are subjected to hydrothermal reaction for 24h at 150 ℃, and the mixture is naturally reactedCooling to room temperature to obtain a brownish black product B; and repeating the steps of cleaning, drying and grinding in the comparative example 1 to obtain the algae-based biochar, wherein the final product has weak magnetic induction through testing.
Test example 1
The magnetic algae-based biochar prepared in the examples 1 to 4 is used for removing Total Phosphorus (TP) in water, and the implementation process comprises the steps of standing tap water for 12 hours, preparing TP solutions with the concentration of 30 mg/L, taking 250ml of each TP solution, adding 100 mg/L of the magnetic algae-based biochar prepared in the examples 1 to 4, oscillating the solutions at a constant temperature of 25 ℃ in a dark place at 150rpm, taking water samples at regular intervals, and determining the concentration of TP in the water samples by adopting a digestion-ascorbic acid method in a national standard analysis method.
Test example 2
The magnetic algae-based biochar prepared in examples 1 to 4 was used for removing low concentration heavy metal cadmium ion (Cd) in water2+) The implementation process comprises the steps of standing tap water for 12 hours, and preparing Cd with the concentration of 200 mu g/L2+Respectively taking 250ml of solution, respectively adding 1-4 prepared magnetic algae-based biochar 100 mg/L, oscillating at constant temperature of 25 ℃ in a dark place at 150rpm, taking water samples at regular intervals, and determining Cd in the water sample by an Agilent 7700x inductively coupled plasma mass spectrometer (ICP-MS)2+The concentration of (c). As can be seen from the test results, the magnetic algal-based biochar prepared in examples 1 to 4 has a good effect on Cd in water2+The adsorption efficiency is high, and the removal rate in 30min is 90.5-95.1%.
Test example 3
The magnetic algae-based biochar prepared in the examples 1 to 4 is used for removing low-concentration antibiotic organic pollutants in water through catalytic degradation, and the implementation process comprises the steps of preparing Sulfamethoxazole (SMX) solutions with the concentration of 1 mg/L, taking 100ml of each sulfamethoxazole solution, adjusting the pH value of the solutions to be 5.00 +/-0.10, adding 100 mg/L of the magnetic algae-based biochar prepared in the examples 1 to 4 and 100 mg/L of hydrogen peroxide respectively, oscillating the solutions at a constant temperature of 25 ℃ in a dark place at 150rpm for 30min, measuring the concentration of SMX in a water sample by using a high performance liquid chromatograph (L C-DAD), wherein the catalytic degradation efficiency of the magnetic algae-based biochar prepared in the examples 1 to 4 on the SMX in the water is high, the removal rate of 30min is kept above 90%, then the magnetic algae-based biochar after catalytic reaction is separated by an external magnetic field, solid-liquid separation is completed, the magnetic algae-liquid separation is repeatedly used after the magnetic algae-based biochar is dried at a constant weight at a temperature of 60 ℃, and the catalytic degradation efficiency of the SMX after the repeated.

Claims (9)

1. A normal-temperature pretreatment-hydrothermal carbonization method for preparing magnetic algae-based biochar is characterized by comprising the following steps: sequentially adding ferrous salt, alkali and ferric salt into the algae sludge, stirring and carrying out magnetic separation to obtain dark green floc A; and then carrying out hydrothermal reaction on the dark green floc A to obtain a brownish black product B, and washing, carrying out solid magnetic separation and drying to obtain the magnetic algae-based biochar.
2. The method of claim 1, wherein: the algae sludge comprises high-concentration algae-rich water, algae mud in a sedimentation tank of a water treatment plant, air-float algae residues and manually salvaged or mechanically removed algae residues, and the mass percentage of the water in the algae sludge is 95-99 wt%.
3. The method of claim 1, wherein: the mass ratio of iron ions in the ferric salt to dry basis in the algae mud is 1: 70-150.
4. The method of claim 1, wherein: the ferrous salt is ferrous sulfate and/or ferrous chloride; the ferric iron salt is ferric trichloride and/or ferric sulfate; the alkali is sodium hydroxide and/or potassium hydroxide.
5. The method of claim 4, wherein: fe2+、OH-、Fe3+The molar ratio of (A) to (B) is 1-1.5: 6-8: 1.
6. The method according to any one of claims 1 to 5, wherein: the stirring temperature is 25-35 ℃, and the rotating speed is 20-50 rpm.
7. The method according to any one of claims 1 to 5, wherein: the temperature of the hydrothermal reaction is 150-250 ℃.
8. Use of magnetic algae-based biochar prepared by the method of any one of claims 1-7 for adsorbing and removing heavy metal ions or total phosphorus in water.
9. The use of magnetic algae-based biochar prepared by the method of any one of claims 1-7 in catalyzing hydrogen peroxide to degrade organic pollutants in water.
CN201811373068.9A 2018-11-19 2018-11-19 Normal-temperature pretreatment-hydrothermal carbonization method for preparing magnetic algae-based biochar Active CN109317100B (en)

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