CN104162404B - Preparation method of adsorbent of rare earth doped hydrated manganese oxide - Google Patents

Abstract

The invention discloses a method for preparing an adsorbent of rare earth-doped hydrated manganese oxide. Firstly, a mixed solution I is prepared by using a MnSO ₄ ·H ₂ O solution with a molar concentration of 2% to 5% and a NaCl solution of 2% to 10%. Add 0.1% to 0.5% KMnO ₄ solution to the mixed solution I to prepare the hydrated manganese dioxide seed crystal mixed solution; perform rare earth doping crystal grain amplification treatment on the hydrated manganese dioxide seed mixed solution; hydrate and oxidize the rare earth doped The manganese mixed solution is subjected to sediment particle size classification treatment, and the precipitate with a particle size greater than 10 μm is subjected to pressure filtration treatment to obtain an adsorbent filter cake; the adsorbent filter cake is dried at 50°C to 75°C for 1.5h to 3h, Until the surface has no obvious moisture, the final adsorbent is obtained. The adsorbent has fast adsorption reaction speed and high adsorption capacity, thereby reducing its dosage in the waste water treatment process and reducing the operating cost of the waste water treatment.

Description

A kind of adsorbent preparation method of rare earth doped hydrated manganese oxide

technical field

The invention relates to the technical field of wastewater treatment, in particular to a method for preparing an adsorbent of rare earth-doped hydrated manganese oxide.

Background technique

At present, traditional nano-metal oxides (such as hydrated manganese oxide, hydrated iron oxide, etc.) have high adsorption capacity for cationic heavy metals such as thallium and cadmium in wastewater. There are many studies on the isothermal adsorption capacity, multi-ion competitive adsorption relationship, and desorption regeneration performance of nano-metal oxides in solution systems. However, nano-metal oxides are rarely used in wastewater treatment projects. This is mainly due to the following points Technical difficulties: First, the particle size of nano-sized metal oxides is small, and it is difficult for nano-scale oxide particles to precipitate and separate from wastewater after adsorbing heavy metals, resulting in no significant reduction in the total heavy metal concentration in treated wastewater. Secondly, the adsorption selectivity of nano-metal oxides is not strong, and it is difficult to remove trace heavy metals in wastewater. When the concentration of ^{Ca 2+} , Pb ²⁺ and other cations in the wastewater is much higher than the concentration of the target heavy metal pollutants (such as Tl, Hg, etc.) ²⁺ occupation, making it difficult to meet the effluent requirements of advanced treatment for trace heavy metals remaining in the treated effluent.

Therefore, the development of a metal oxide adsorbent with highly selective adsorption for trace heavy metals (such as Tl, Hg, etc.) in wastewater, high adsorption capacity, and easy precipitation and separation has important application prospects and economic and social value.

Contents of the invention

The purpose of this invention is to provide a kind of adsorbent preparation method of rare earth doped hydrated manganese oxide, the adsorbent prepared by the preparation method has fast adsorption reaction speed and high adsorption capacity, thereby reducing its dosage in the wastewater treatment process , reducing the operating cost of wastewater treatment.

A method for preparing an adsorbent of rare earth-doped hydrated manganese oxide, the preparation method comprising:

Mixed solution I was prepared by using MnSO ₄ ·H ₂ O solution with a molar concentration of 2% to 5% and NaCl solution with 2% to 10%, and added 0.1% to 0.5% KMnO ₄ solution to the mixed solution I. Prepare the hydrated manganese dioxide seed crystal mixed solution under certain reaction conditions;

The hydrated manganese dioxide seed mixture solution is subjected to rare earth doping crystal grain amplification treatment, which specifically includes: using 0.2% to 1% CeCl ₃ solution and 2% to 5% MnSO ₄ ·H ₂ O solution, according to a certain The volume ratio of the mixed solution II is prepared into the mixed solution II, and the mixed solution II is mixed with the hydrated manganese dioxide seed crystal mixed solution according to a certain volume ratio to prepare the mixed solution III, and then 1% of the mixed solution is added to the mixed solution III ～3% KMnO ₄ solution, under the condition of 20～40°C, stirring and reacting the mixed solution for 1.5～3 hours to obtain the rare earth doped hydrated manganese oxide mixed solution;

The rare earth-doped hydrated manganese oxide mixed solution is subjected to sediment particle size classification treatment, and the precipitate with a particle size greater than 10 μm is subjected to pressure filtration treatment, and the adsorbent filter cake obtained after pressure filtration treatment is collected;

The filter cake of the adsorbent is dried at 50° C. to 75° C. for 1.5 h to 3 h until there is no obvious moisture on the surface to obtain the final rare earth-doped hydrated manganese oxide adsorbent.

During the preparation process of the hydrated manganese dioxide seed mixed solution:

The molar concentration of the KMnO ₄ solution is preferably 0.4%; the molar concentration of the MnSO ₄ ·H ₂ O solution is preferably 3%; the molar concentration of the NaCl solution is preferably 7%.

During the preparation process of the hydrated manganese dioxide seed mixed solution:

The volume ratio of the MnSO ₄ ·H ₂ O solution to the NaCl solution is between 5:1 and 2:1, preferably 3:1;

And the volume ratio of the mixed solution I to the KMnO ₄ solution is between 4:1 and 1:1, preferably 2:1.

The set reaction conditions are as follows: the temperature is between 90-100° C., and the stirring reaction time is between 1.5-3 hours, preferably 2 hours.

In the process of rare earth doped grain amplification treatment:

The concentration of the MnSO ₄ ·H ₂ O solution used is preferably 3%, the concentration of the CeCl ₃ solution used is preferably 0.7%, and the MnSO ₄ ·H ₂ O solution and the CeCl ₃ solution are in accordance with the ratio of 8:1 to 12: The volume ratio of 1 was prepared as the mixed liquid II.

In the process of rare earth doped grain amplification treatment:

The volume ratio of the mixed solution II to the hydrated manganese dioxide seed mixed solution is between 3:1 and 5:1, preferably 4:1;

_The molar concentration of the KMnO solution added to the mixed solution III is preferably 2%, and the volume ratio of the mixed solution III to the KMnO solution is between ₃ :1 and 1:1, preferably 2 :1.

In the process of rare earth doped grain amplification treatment:

The time for stirring and reacting the mixed solution is preferably 2 hours.

It can be seen from the above technical solution provided by the present invention that the adsorption of the adsorbent prepared by the preparation method has the characteristics of fast reaction speed and high adsorption capacity, which can reduce the dosage of adsorbent in the wastewater treatment process and reduce the waste water treatment. operating costs.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For Those of ordinary skill in the art can also obtain other drawings based on these drawings on the premise of not paying creative work.

Fig. 1 is a schematic flow chart of the preparation method of the adsorbent of rare earth doped hydrated manganese oxide provided by the embodiment of the present invention.

detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The embodiment of the present invention utilizes various physical and chemical reaction mechanisms such as oxidation-reduction reaction and co-precipitation reaction in the solution system to prepare a rare earth-doped hydrated manganese oxide adsorbent rich in surface hydroxyl active exchange sites, which can be applied to It is used for the deep adsorption and removal of heavy metals such as thallium, cadmium, and lead in wastewater. The embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings. Figure 1 is a schematic flow chart of the preparation method for the adsorbent of rare earth-doped hydrated manganese oxide provided by the embodiments of the present invention. The method includes:

Step 11: Prepare a mixed solution I by using a MnSO ₄ ·H ₂ O solution with a molar concentration of 2% to 5% and a 2% to 10% NaCl solution, and add 0.1% to 0.5% KMnO ₄ to the mixed solution I Solution, the hydrated manganese dioxide seed crystal mixed solution is obtained under the set reaction conditions;

In this step, the formula for preparing the mixed solution of hydrated manganese oxide seed crystals can be: KMnO ₄ solution with a molar concentration of 0.1% to 0.5%, preferably 0.4%; MnSO ₄ ·H ₂ O solution with a molar concentration of 2% to 5% , the concentration is preferably 3%; 4% to 10% molar concentration of NaCl solution, the concentration is preferably 7%. For convenience, the following concentrations are molar concentrations.

And under the premise of the above formula, the volume ratio of the MnSO ₄ ·H ₂ O solution to the NaCl solution is between 5:1 and 2:1, preferably 3:1; and the mixed solution I and KMnO ₄ The volume ratio of the solution is between 4:1 and 1:1, preferably 2:1.

The reaction conditions set above are as follows: the temperature is between 90-100° C., and the stirring reaction time is between 1.5-3 hours, preferably 2 hours.

Step 12: performing rare earth-doped crystal grain enlargement treatment on the hydrated manganese dioxide seed mixture;

In this step, the specific operation is: use 0.2%-1% CeCl ₃ (cerium chloride) solution and 2%-5% MnSO ₄ ·H ₂ O solution to prepare mixed solution II according to a certain volume ratio, Mix the mixed solution II with the hydrated manganese dioxide seed mixed solution according to a certain volume ratio to prepare mixed solution III, then add 1% to ₃ % KMnO4 solution to the mixed solution III, at 20 Under the condition of ~40°C, the mixed solution is stirred and reacted for 1.5-3 hours to obtain the rare earth-doped hydrated manganese oxide mixed solution;

In the above process, the concentration of the MnSO ₄ ·H ₂ O solution used is preferably 3%, the concentration of the CeCl ₃ solution used is preferably 0.7%, and the MnSO ₄ ·H ₂ O solution and the CeCl ₃ solution are in accordance with 8 : The volume ratio of 1 to 12:1 is prepared into the mixed solution II, preferably 10:1.

And the volume ratio of the mixed solution II to the hydrated manganese dioxide seed mixed solution is between 3:1 and 5:1, preferably ₄ :1; the KMnO solution added in the mixed solution III The molar concentration of is preferably 2%, and the volume ratio of the mixed solution III to the KMnO ₄ solution is between 3:1 and 1:1, preferably 2:1.

In addition, during the rare earth-doped grain enlargement process, the time for stirring and reacting the mixed solution is between 1.5-3 hours, preferably 2 hours; and the reaction temperature is between 20-40°C.

Step 13: performing sediment particle size classification treatment on the rare earth-doped hydrated manganese oxide mixed solution, taking sediments with a particle size greater than 10 μm for pressure filtration treatment, and collecting the adsorbent filter cake obtained after the pressure filtration treatment;

In this step, a hydrocyclone can be used to classify the rare earth-doped manganese oxide hydrate mixed solution for sediment particle size classification, and select the precipitate with a particle size larger than 10 μm to enter the filter press, and then perform press filter dehydration treatment to obtain adsorption agent filter cake.

Step 14: drying the filter cake of the adsorbent at 50° C. to 75° C. for 1.5 h to 3 h until there is no obvious moisture on the surface to obtain the final rare earth-doped hydrated manganese oxide adsorbent.

The rare earth-doped hydrated manganese oxide adsorbent prepared by the above steps can be applied to deep adsorption and removal of heavy metals such as thallium, cadmium and lead in wastewater.

In summary, the preparation method provided by the embodiments of the present invention has the following advantages and significance:

(1) Through the two-step process of seed crystal preparation and rare earth-doped grain amplification, the particle size of nano-metal oxides can be controlled within a certain range. After completing the process of adsorbing heavy metals in wastewater, the dosing-type adsorbent can be precipitated and separated from wastewater, which improves its engineering application value.

(2) Doping with cerium chloride improves the selective adsorption of traditional hydrated manganese oxide, and can be used to remove trace amounts of heavy metals such as Tl and Hg in wastewater.

(3) Due to the fast adsorption reaction speed and high adsorption capacity of the adsorbent, its dosage in the wastewater treatment process is reduced, and the operating cost of wastewater treatment is reduced.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person familiar with the technical field can easily conceive of changes or changes within the technical scope disclosed in the present invention. Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (7)

1. a kind of sorbent preparation method of rear-earth-doped hydrated manganese oxide is it is characterised in that described preparation method includes:

Mnso using mass percentage concentration 2%～5%₄·h₂O solution and the nacl solution of mass percentage concentration 2%～10% Prepare mixed liquor, add the kmno of mass percentage concentration 0.1%～0.5% in described mixed liquor₄Solution, anti-set Hydrated manganese dioxide crystal seed mixed liquor is obtained under the conditions of answering；

Rear-earth-doped crystal grain processing and amplifying is carried out to described hydrated manganese dioxide crystal seed mixed liquor, specifically includes: using quality hundred Divide the cecl of concentration 0.2%～1%₃Solution and the mnso of mass percentage concentration 2%～5%₄·h₂O solution, according to certain body Long-pending ratio is configured to mixed liquor, by described mixed liquor with described hydrated manganese dioxide crystal seed mixed liquor according to certain volume ratio Mixing, is configured to mixed liquor, then adds mass percentage concentration 1%～3%kmno in described mixed liquor₄Solution, 20 Under the conditions of～40 DEG C, by mixed solution stirring reaction 1.5～3h, obtain rear-earth-doped hydrated manganese oxide mixed liquor；

Precipitate particle sizes staged care is carried out to described rear-earth-doped hydrated manganese oxide mixed liquor, takes the precipitation that particle diameter is more than 10 μm Thing carries out filter pressing process, collects the adsorbent filter cake obtaining after filter pressing is processed；

Described adsorbent filter cake is dried 1.5h～3h under the conditions of 50 DEG C～75 DEG C, to the no obvious moisture in surface, obtains final Rear-earth-doped hydrated manganese oxide adsorbent.

2. according to claim 1 the sorbent preparation method of rear-earth-doped hydrated manganese oxide it is characterised in that in described water Close in manganese dioxide crystal seed mixed liquor preparation process:

Described kmno₄The mass percentage concentration of solution is 0.4%；Described mnso₄·h₂The mass percentage concentration of o solution is 3%； The mass percentage concentration of described nacl solution is 7%.

3. according to claim 1 the sorbent preparation method of rear-earth-doped hydrated manganese oxide it is characterised in that in described water Close in manganese dioxide crystal seed mixed liquor preparation process:

Described mnso₄·h₂The volume ratio of o solution and described nacl solution is between 5:1～2:1；

And described mixed liquor and kmno₄The volume ratio of solution is between 4:1～1:1.

4. according to claim 1 the sorbent preparation method of rear-earth-doped hydrated manganese oxide it is characterised in that described setting Reaction condition be:, between 90～100 DEG C, the stirring reaction time is between 1.5～3h for temperature.

5. according to claim 1 rear-earth-doped hydrated manganese oxide sorbent preparation method it is characterised in that carry out dilute During soil doping crystal grain processing and amplifying:

The mnso being adopted₄·h₂The mass percentage concentration of o solution is 3%, the cecl being adopted₃The mass percentage concentration of solution For 0.7%, and described mnso₄·h₂O solution and cecl₃Solution is configured to mixed liquor according to the volume ratio of 8:1～12:1.

6. according to claim 1 rear-earth-doped hydrated manganese oxide sorbent preparation method it is characterised in that carry out dilute During soil doping crystal grain processing and amplifying:

The volume ratio of described mixed liquor and described hydrated manganese dioxide crystal seed mixed liquor is between 3:1～5:1；

The kmno being added in described mixed liquor₄The mass percentage concentration of solution be 2%, and described mixed liquor with described kmno₄The volume ratio of solution is between 3:1～1:1.

7. according to claim 1 rear-earth-doped hydrated manganese oxide sorbent preparation method it is characterised in that carry out dilute During soil doping crystal grain processing and amplifying:

The time of described mixed solution stirring reaction is specially 2h.