CN106861605A - Activated carbon supported nanometer Fe Al（Hydrogen）The preparation method and applications of oxide particle composites - Google Patents

Abstract

The invention specifically relates to a preparation method and application of activated carbon-supported nano Fe-Al (hydr) oxide particle composite materials. Its preparation method is: dissolve the salt containing trivalent ion Fe ³⁺ and the salt of trivalent ion Al ³⁺ in deionized water to form mixed salt solution A; prepare another portion of boiling deionized water, and continue heating . Add the mixed salt solution A dropwise into boiling deionized water to form solution B, and control its pH between 5-7.5. Continue to heat the solution B until it forms a brown Fe–Al (hydroxide) oxide sol solution C, cool it to room temperature, pour off the supernatant, and add a certain amount of activated carbon to the sol solution C to form a sol and activated carbon a mixture of D. The invention utilizes a relatively drastic method to form iron-aluminum salts into nanoparticles and efficiently and uniformly load them on the activated carbon, the materials used are cheap and easy to obtain, the method involves simple equipment, the operation is more convenient, and the result is easy to control.

Description

Preparation method of activated carbon-supported nano Fe-Al (hydroxide) oxide particle composite material and its application

technical field

The invention belongs to the technical field of composite material preparation, in particular to a preparation method and application of activated carbon-supported nano Fe-Al (hydr) oxide particle composite material.

Background technique

In recent years, the eutrophication of water bodies has become one of the serious water pollution problems facing the world. The eutrophication of water bodies and the excessive reproduction of algae lead to the deterioration of water quality and the degradation of lakes, seriously destroying the ecological environment of water bodies, and threatening the survival of aquatic organisms and human health. Since phosphorus is the most important limiting factor for algae proliferation, controlling the discharge of phosphorus-containing wastewater is the key to solving water eutrophication.

At present, the phosphorus removal methods commonly used in wastewater treatment processes are mainly biological methods, chemical precipitation methods, ion exchange methods, membrane adsorption methods, etc. Among them, biological and chemical precipitation usually cannot handle low-concentration phosphate solutions. Membrane technology requires high investment and operating costs. Therefore, adsorption technology proved to be a more promising method for phosphorus removal. Its advantages are simple operation and low cost, it can handle low-concentration phosphate solution, and it has relatively high selectivity and high adsorption capacity. In addition, phosphorus, as an essential element for biomass growth, may be depleted in the near future, so another advantage of the adsorption method is the recovery and utilization of phosphate in wastewater.

At present, a large number of materials have been studied as adsorbents for phosphorus removal, including activated carbon, zeolite, calcite, bentonite, montmorillonite, vermiculite, metals, metal oxides, etc. Among them, metal (water) oxides exhibit great adsorption affinity for phosphorus, especially aluminum, calcium, iron, and zirconium compounds. Recently, the adsorption behavior of several multicomponent metal adsorbents has been investigated, where the difference in physicochemical properties affects the adsorption performance, such as surface area, porosity, and surface charge distribution, etc. For example, Fe–Mn oxides, Fe–Zr oxides, Fe–Al (water) oxides, and Fe–Al–Mn ternary oxides inherit the advantages of each component and thus have better adsorption effects. In addition, the research of nanometer metal/metal oxide adsorbents, etc. has also attracted much attention, and its high adsorption performance is due to the large specific surface area, high reactivity and no diffusion resistance.

It is well known that activated carbon is a traditional adsorbent capable of removing various organic and inorganic pollutants from the aqueous phase. It is readily available and inexpensive. However, its adsorption of phosphate was not significant. Activated carbon has a large specific surface area (hundreds to one kilogram per square meter) and large pores (>50 nanometers). If the selected multi-component metal oxides can be uniformly loaded on the activated carbon to form a new adsorbent surface, then the disadvantage of easy aggregation of nanoparticles will be overcome, and the nanoparticles can be used more effectively, while the adsorption materials costs will also be reduced. If the phosphorus adsorption performance of the adsorbent is good, it will be a promising high-efficiency phosphorus adsorbent.

Contents of the invention

The purpose of the present invention is to address the above problems, and to provide a preparation method of activated carbon-loaded nano Fe-Al (hydr) oxide particle composite material. The composite material has low production cost, high adsorption capacity, wide application range and great potential for practical production.

Another inventive object of the present invention is to provide the application of the above-mentioned composite material.

Concrete technical scheme of the present invention is:

The preparation method of activated carbon supported nanometer Fe-Al (hydr) oxide particle composite material comprises the following steps:

1) The salt containing Fe ³⁺ and the salt containing Al ³⁺ are dissolved in deionized water to obtain a mixed salt solution A containing Fe ³⁺ and Al ³⁺ , and the molar concentration of the mixed salt solution A is controlled at 1-2mol/ L, the molar concentration ratio of Fe ³⁺ and Al ³⁺ is controlled at 10:1~5:1; the salt containing Fe ³⁺ is FeCl ₃ 6H ₂ O; the salt containing Al ³⁺ is AlCl ₃ 6H ₂ O.

2) Put deionized water in a beaker and heat to boil, add the mixed salt solution dropwise into the boiled deionized water to form solution B, and control its pH to 5-7.5;

3) Continue heating the solution until the formation of tan Fe–Al hydroxide sol C, then cool the sol C to room temperature, pour off the supernatant, and then add activated carbon to sol C to form a mixture D of sol and activated carbon (Activated carbon quality g: sol solution C volume ml=0.5-2g: 200ml, when the activated carbon specific surface area is large, the activated carbon quality is lower; otherwise, higher);

4) The mixture D was fully ultrasonically mixed, and dried by rotary evaporation to a powder state, then the collected powder was washed thoroughly with deionized water repeatedly, and finally dried in an oven at a temperature not exceeding 250°C.

The composite material prepared by the method described above is used to remove phosphorus in water. When the concentration of phosphorus in water is 80 mg/L and the amount of the composite material added is 1 g/L, the adsorption capacity is 29.3 mg/g. The adsorption of phosphate by materials is not only the electrostatic effect of anion and cation, but also the coordination effect related to phosphate radical, so that the phosphorus removal has a certain selectivity and is not easily affected by the competition of other anions in the solution. The positive effects of the present invention are reflected in:

(1) The composite material has low production cost, high adsorption capacity, wide application range, and can be widely used in actual production.

(2) Use a more drastic method to form iron and aluminum salts into nanoparticles and load them on activated carbon efficiently and uniformly. The materials used are cheap and easy to obtain, and are environmentally friendly. The method involves simple equipment, relatively convenient operation, and the result is easy to control.

Description of drawings

Fig. 1 is the scanning electron micrograph of the composite material 1.5AC-Fe/Al that prepares in embodiment 1

Figure 2a is the XRD pattern of nano Fe-Al (hydroxide) oxide

Figure 2b is the XRD pattern of composite activated carbon supported nano-Fe-Al (hydr) oxide (1.5AC-Fe/Al)

Fig. 3 is the composite material 1.5AC-Fe/Al prepared in embodiment 1, the composite material 2.5AC-Fe/Al prepared in comparative example 2 and the composite material 3.5AC-Fe/Al prepared in comparative example 3. Comparison curve of phosphorus adsorption capacity, where *Ce is the adsorption equilibrium concentration, and q is the adsorption amount.

detailed description

The present invention is further described below in conjunction with embodiment, but does not limit protection scope of the present invention.

Example 1:

Dissolve FeCl ₃ 6H ₂ O and AlCl ₃ 6H ₂ O in 50ml deionized water to prepare Fe ³⁺ and Al ³⁺ mixed solution, the molar ratio of Fe ³⁺ to Al ³⁺ in the mixed solution is 9:1 , put 200ml of deionized water in a beaker and heat to boil, add the mixed salt solution dropwise into the boiled deionized water and stir while controlling the pH of the solution in the neutral range. The solution was continuously heated until a brown Fe–Al hydroxide sol was formed, the concentration of the sol was 1mol/L, and then the sol was cooled to room temperature, and 1.5g of activated carbon was added to the sol for 30 minutes of ultrasonication, and the solution was placed in a constant temperature water bath at 75°C. Rotary evaporation in a medium to powder form, repeated washing with deionized water, and drying at 105°C to obtain a composite material, which is designated as "1.5AC-Fe/Al". Fig. 1 is the scanning electron micrograph of this composite material 1.5AC-Fe/Al, can clearly see that Fe-Al (hydroxide) oxide is in activated carbon surface and pore diameter by Fig. 1, and this shows that Fe-Al (hydroxide) oxide successfully supported on activated carbon. In the composite material, the surface of activated carbon is uniformly covered with fine particles.

Comparative example 1:

Using the same steps as in Example 1, only changing the molar ratio of iron ions to aluminum ions to 5:5 or 7:3, it is difficult for the obtained iron-aluminum (hydr) oxide particles to maintain a fine nanoscale crystal state.

Comparative example 2:

Using the same parameters and steps as in Example 1, only the addition of activated carbon in the Fe-Al hydroxide sol was changed to 2.5g, and finally a composite material was obtained, which was denoted as "2.5AC-Fe/Al". In this composite material , the surface of the activated carbon will be partially exposed, and the adsorption capacity of the composite material will be difficult to exert.

Comparative example 3:

Using the same parameters and steps as in Example 1, only the addition of activated carbon in the Fe-Al hydroxide sol was changed to 3.5g, and finally a composite material was obtained, which was denoted as "3.5AC-Fe/Al". Similarly, the In the composite material, the surface of the activated carbon will be partially exposed, and the adsorption capacity of the composite material will be difficult to exert.

Comparative example 4:

Using the same parameters and steps as in Example 1, only the addition of activated carbon in the Fe-Al hydroxide sol was changed to 0.2g, and finally a composite material was obtained, denoted as "0.2AC-Fe/Al", too much iron Aluminum (hydr) oxide nanoparticles accumulate on the activated carbon or are lost during the step of washing the material with deionized water, resulting in waste.

Comparative example 5:

Using the same parameters and steps as in Example 1, and directly forming nanoparticles (without adding activated carbon) after the formation of brown Fe—Al hydroxide sol, pure Fe/Al (hydroxide) oxide nanoparticles were prepared. Carry out XRD analysis to it, the result is shown in Fig. 2 in detail, and Fig. 2 a is the XRD pattern of nano-Fe-Al (hydr) oxide, and Fig. 2 b is the XRD pattern of 1.5AC-Fe/Al, compares known by XRD analysis, in the same angle, indicating that nano-Fe-Al(hydr)oxides were successfully supported and that the nanoparticles on the surface of activated carbon were of crystalline structure.

Example 2:

Weigh 0.04 g of the 1.5AC-Fe/Al material prepared in Example 1 into a series of Erlenmeyer flasks, and then add 40 ml of KH ₂ PO with a mass concentration of 5, 10, 20, 40, 60, and 80 mg/L ₄ solution (the background solution is pH=3, containing 10mmol/LNaCl and 5mmol/LCaCl ₂ ), sealed and placed in a constant temperature shaker, and shaken at a temperature of (20±0.5°C) at a rate of 180r/min for 48h (adsorption equilibrium time determined in advance). Then put it on a flat surface and let it settle overnight to let the adsorbent settle and then filter the supernatant with a 0.45um membrane filter. The adsorption amount of phosphorus is determined by the difference between the adsorption equilibrium and the initial concentration, and is determined by the ammonium molybdate colorimetric method . Phosphorus adsorption capacity (q, mg/g) and distribution coefficient (K _d , L/g) are calculated by the following formula:

q=V(C ₀ -C _e )/m (1)

K _d =q/C _e (2)

In the formula, V is the volume of phosphorus solution (L), C ₀ and C _e are the phosphorus concentration (mg/L) at the initial and equilibrium state of the solution, and m is the dosage of adsorbent (g).

In this application, activated carbon was purchased from Nanjing Zhengsen Chemical Industry Co., Ltd., and then rinsed with deionized water to remove soluble matter and dried completely at 105 °C. All chemicals were of analytical grade without further purification. The phosphorus stock solution is a solution prepared by dissolving KH ₂ PO ₄ in deionized water.

The calculation results show that: in the case of a certain amount of composite material, the greater the initial concentration of P, the greater the adsorption capacity. When the initial concentration of P is 80 mg/L, the adsorption capacity of the composite material is 29.3 mg/L, which proves that it has High adsorption capacity.

With the 1.5AC-Fe/Al prepared in Example 1, the 2.5AC-Fe/Al prepared in Comparative Document 2, and the 3.5AC-Fe/Al prepared in Comparative Document 3, these three kinds of materials are to phosphorus The adsorption capacity was compared and analyzed, and the results are shown in Figure 3. From Figure 3, it can be seen that the adsorption capacity of 1.5AC-Fe/Al is much stronger than that of 2.5AC-Fe/Al and 3.5AC-Fe/Al.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (6)

1. The preparation method of activated carbon supported nanometer Fe-Al (hydroxide) oxide particle composite material, is characterized in that comprising the following steps: 1) Dissolve the salt containing Fe ³⁺ and the salt containing Al ³⁺ in deionized water to prepare a mixed salt solution A containing Fe ³⁺ and Al ³⁺ , and the molar concentration of the mixed salt solution A is controlled at 1-2 mol /L, the molar concentration ratio of Fe ³⁺ and Al ³⁺ is controlled at 10:1~5:1; 2) Put deionized water in a beaker and heat to boil, add the mixed salt solution dropwise into the boiled deionized water to form solution B, and control its pH to 5-7.5; 3) The solution was continuously heated to form a tan Fe–Al hydroxide sol C, and then the sol C was cooled to room temperature, and the supernatant was poured off, and then activated carbon was added to the sol C to form a mixture D of the sol and activated carbon ; 4) The mixture D was fully ultrasonically mixed, and dried by rotary evaporation to powder, then the collected powder was rinsed repeatedly with deionized water, and finally dried in an oven at a drying temperature not exceeding 250°C to obtain a composite material. 2 . The method for preparing activated carbon-supported nano-Fe-Al (hydr) oxide particle composite material according to claim 1 , characterized in that: the salt containing Fe ³⁺ is FeCl ₃ ·6H ₂ O . 3. The method for preparing activated carbon-supported nano-Fe-Al (hydr)oxide particle composite material according to claim 1, characterized in that: the salt containing Al ³⁺ is AlCl ₃ ·6H ₂ O. 4. According to the preparation method of activated carbon-loaded nano-Fe-Al (hydrogen) oxide particle composite material according to claim 1, it is characterized in that: activated carbon mass g: sol solution C volume ml=0.5-2:200, when activated carbon specific surface area When it is large, the quality of activated carbon should be lower; otherwise, the quality should be higher. 5. The application of the composite material prepared by the method according to any one of claims 1 to 4, characterized in that: the composite material is used for the removal of phosphorus in water. 6. The application according to claim 5, characterized in that: when the concentration of phosphorus in water is 80 mg/L and the amount of the composite material added is 1 g/L, the adsorption capacity is 29.3 mg/g.