CN106000324A - Preparation method of magnetic organic hydrotalcite - Google Patents

Abstract

The invention discloses a preparation method of magnetic organic hydrotalcite. Include the following steps in sequence: take the FeCl solution, place it in a water bath with a constant temperature of 70-80°C, and simultaneously add _2-4mL of 30% (mass fraction) hydrogen peroxide and a certain amount of dilute NaOH solution dropwise, keeping the pH value at 12-80°C. 13. React for 2-3 hours, transfer to an autoclave, heat up to 150-180°C within 1 hour, continue to react for 4-8 hours, and cool down to room temperature naturally. During this process, a precipitate with a layered structure is formed, and the precipitate is separated and removed. Wash 2 to 3 times with ionized water; add the precipitated solid to a surfactant solution with a concentration of 2 to 4 mol/L, the solid-to-liquid ratio is 1:10 to 1:50, and stir in a water bath at 50 to 80°C for 2 to After 8 hours of magnetic field separation, wash with deionized water for 2 to 3 times, and dry at 70 to 90°C to obtain a magnetic organic hydrotalcite. This structure is beneficial for the adsorption of pollutants and at the same time for separation.

Description

A kind of preparation method of magnetic organic hydrotalcite

technical field

The invention relates to the development of new materials for environmental pollution control, in particular to a preparation method of magnetic organic hydrotalcite.

Background technique

Hydrotalcite-like compounds (LDHs) are compounds formed by stacking interlayer anions and positively charged laminates. The general chemical structure formula of hydrotalcite is: [M ²⁺ _1-x M ³⁺ x(OH) ₂ ] ^x+ [(A ^n- ) _x/n mH ₂ O], where M ²⁺ and M ³⁺ are respectively Divalent and trivalent metal cations located on the main laminate, such as Mg ²⁺ , Ni ²⁺ , Zn ²⁺ , Mn ²⁺ , Cu ²⁺ , Co ²⁺ , Pd ²⁺ , Fe ²⁺ and other divalent cations Al ³⁺ , Cr ³⁺ , Co ³⁺ , Fe ³⁺ and other trivalent cations can form hydrotalcite; ^An– is an interlayer anion, which can include inorganic anions, organic anions, complex anions, isopoly and hetero Polyanions; x is the molar ratio of M ³⁺ /(M ²⁺ +M ³⁺ ), about 4:1 to 2:1; m is the number of interlayer water molecules. Its structure is similar to that of brucite Mg(OH) ₂ , and the main laminates are formed by octahedrons sharing edges. The divalent metal cation M ²⁺ located on the laminate can be isomorphically replaced by the trivalent metal cation M ³⁺ with a similar half price within a certain proportion, so that the laminate is positively charged and there are exchangeable anions between the layers Balanced with the positive charge on the laminate, the overall structure of LDHs is electrically neutral. The anions between the layers can be exchanged, and after a series of modifications, the hydrotalcite material can obtain many kinds of substances with different properties.

Some compounds are introduced into the interlayer domain by means of ion exchange to form molecular-level pillars, and a new type of molecular-level composite material with large pore size and regular distribution is produced, which has the characteristics of adsorption and transformation of organic molecules. There are many varieties of hydrotalcite, the adjustability of the pillar compound, the pore size and adsorption properties of the modified clay material can be controlled artificially, so the material can be prepared according to different uses, and it is widely used in petrochemical, environmental protection and many other fields Wide application prospects.

The most common way is to obtain organic layered clay by modification, that is, after the interlayer inorganic cations are exchanged with organic cations (usually quaternary ammonium salt cations), an organic layer is formed, and the hydrophobicity of the interlayer and the outer surface is improved. , so that organic pollutants can be more effectively adsorbed and removed. Due to the excellent adsorption properties of the organic layer, it has a wide application potential in the field of environmental protection. The organically modified hydrotalcite has a better adsorption effect on some organic substances with strong hydrophilicity. However, there is the problem of difficult separation after adsorption. If it is to be separated cleanly, it needs to go through multiple steps, which is time-consuming and laborious.

Contents of the invention

The object of the present invention is to provide a preparation method of magnetic organic hydrotalcite to overcome the deficiency of single structure of iron oxide in the prior art.

The technical scheme that the present invention adopts is to comprise the following steps successively:

1) Dissolve FeCl ₂ in water and prepare a solution with a concentration of 2-3mol/L. Take 500mL of the solution, place it in a water bath with a constant temperature of 70-80°C, and add 30% (mass fraction) hydrogen peroxide dropwise at the same time. 4mL and a certain amount of dilute NaOH solution, keep the pH value at 12~13, react for 2~3h, transfer to an autoclave, heat up to 150~180°C within 1h, continue to react for 4~8h, cool naturally to room temperature, During this process, a precipitate with a layered structure is formed, the precipitate is separated, and washed 2 to 3 times with deionized water;

2) Add the precipitated solid into a surfactant solution with a concentration of 2-4mol/L, the solid-to-liquid ratio is 1:10-1:50, stir in a water bath at 50-80°C for 2-8 hours, and after magnetic field separation Washing with deionized water for 2 to 3 times and drying at 70 to 90 DEG C can obtain a magnetic organic hydrotalcite.

The surfactant is an alkyl sulfonate with an alkyl carbon number of 12 or more, such as sodium dodecylbenzenesulfonate, sodium cetylsulfonate, etc.

The advantage of the present invention is that part of the divalent iron ions are oxidized by hydrogen peroxide to produce ferric iron, and the divalent ions and the generated trivalent ions will produce magnetic co-precipitation under the action of alkali in a water bath at 70-80°C to form lamellar water. Talc structure, and then exchange surfactants between the sheets to make the surface change from hydrophobic to hydrophilic. This structure is conducive to the adsorption and removal of organic pollutants, and is conducive to separation after removal.

detailed description

Further provide 3 embodiments of the present invention below:

Example 1

Dissolve _FeCl2 in water and make a solution with a concentration of 3mol/L. Take 500mL of this solution and place it in a water bath with a constant temperature of 80°C. At the same time, add 4mL of 30% (mass fraction) hydrogen peroxide and a certain amount of NaOH dilute solution dropwise. , keep the pH value at 13, react for 3 hours, transfer to an autoclave, raise the temperature to 180°C within 1 hour, continue the reaction for 8 hours, and naturally cool to room temperature. During this process, a precipitate with a layered structure is formed, the precipitate is separated, and deionized Wash 3 times with water; add the precipitated solid to the sodium dodecylbenzenesulfonate solution with a concentration of 4 mol/L, the solid-to-liquid ratio is 1:50, stir in a water bath at 80°C for 8 hours, separate with a magnetic field and use a deionized After washing with water for three times and drying at 90°C, a magnetic organic hydrotalcite can be obtained.

Add 1 g of magnetic organic hydrotalcite to a p-nitrophenol solution with a concentration of 15 mg/L and a volume of 1 L, stir for 2 hours, separate with a magnetic field, measure the concentration of the supernatant with a UV-visible spectrophotometer, and the removal rate is 92.2%. Liquid can be drained.

Example 2

Dissolve _FeCl2 in water and configure it as a solution with a concentration of 2mol/L. Take 500mL of this solution and place it in a water bath with a constant temperature of 70°C. At the same time, add 2mL of 30% (mass fraction) hydrogen peroxide and a certain amount of dilute NaOH solution dropwise. , keep the pH value at 12, react for 2 hours, transfer to an autoclave, raise the temperature to 150°C within 1 hour, continue the reaction for 4 hours, and naturally cool to room temperature. During the process, a precipitate with a layered structure is formed, the precipitate is separated, and deionized Wash 2 times with water; add the precipitated solid to the sodium hexadecylsulfonate solution with a concentration of 2mol/L, the solid-to-liquid ratio is 1:10, stir in a water bath at 50°C for 2h, separate with deionized water after magnetic field separation After washing twice and drying at 70°C, a magnetic organic hydrotalcite can be obtained.

Add 1 g of magnetic organic hydrotalcite to a p-nitrophenol solution with a concentration of 15 mg/L and a volume of 1 L, stir for 2 h, separate with a magnetic field, measure the concentration of the supernatant with a UV-visible spectrophotometer, and the removal rate is 95.4%. Liquid can be drained.

Example 3

Dissolve _FeCl2 in water and configure it as a solution with a concentration of 3mol/L. Take 500mL of this solution and place it in a water bath with a constant temperature of 80°C. At the same time, add 3mL of 30% (mass fraction) hydrogen peroxide and a certain amount of NaOH dilute solution dropwise. , keep the pH value at 13, react for 3 hours, transfer to an autoclave, raise the temperature to 160°C within 1 hour, continue the reaction for 5 hours, and naturally cool to room temperature. During this process, a precipitate with a layered structure is formed, the precipitate is separated, and deionized Wash 3 times with water; add the precipitated solid to the sodium dodecylbenzenesulfonate solution with a concentration of 3mol/L, the solid-to-liquid ratio is 1:40, stir in a water bath at 80°C for 8h, and separate with a deionized After washing with water for three times and drying at 90°C, a magnetic organic hydrotalcite can be obtained.

Add 1 g of magnetic organic hydrotalcite to p-nitrobenzene with a concentration of 5 mg/L and a volume of 1 L, stir for 2 hours, separate in a magnetic field, measure the concentration of the supernatant with a UV-visible spectrophotometer, and the removal rate is 99.2%. can be discharged.

Claims (3)

1. a preparation method for magnetic organic hydrotalcite, is characterized in that in turn including the following steps:

1) by FeCl₂It is dissolved in water, is configured to the solution that concentration is 2～3mol/L, take this solution of 500mL, put In constant temperature 70～80 DEG C of water-baths, it is simultaneously added dropwise 30% (mass fraction) hydrogen peroxide 2～4mL and a certain amount of NaOH dilute molten Liquid, keeping pH value is 12～13, reacts 2～3h, proceeds in autoclave, be warmed up to 150～180 DEG C in 1h, continues anti- Answering 4～8h, naturally cool to room temperature, form the precipitation with layer structure, precipitate and separate in this process, deionization is washed 2～3 times；

2) being joined by the solid that precipitation obtains in the surfactant solution that concentration is 2～4mol/L, solid-to-liquid ratio is 1:10～1: 50, in 50～80 DEG C of stirred in water bath 2～8h, it is washed with deionized after magnetic field separation 2～3 times, 70～90 DEG C of drying, i.e. Available a kind of magnetic organic hydrotalcite.

The preparation method of a kind of magnetic organic hydrotalcite the most as claimed in claim 1, it is characterised in that: surfactant used Atomic number of alkyl carbon 12 or more than 12 alkylsulfonate.

The preparation method of a kind of magnetic organic hydrotalcite the most as claimed in claim 2, it is characterised in that: surfactant used For dodecylbenzene sodium sulfonate, sodium cetanesulfonate.