CN106984258A - A kind of preparation and application of hypochlorite intercalation layered composite metal hydroxides - Google Patents

Abstract

The invention relates to a ^{hypochlorite intercalated layered} composite metal hydroxide for removing pollutants in water and its preparation and application. Mix with sodium carbonate solution in deionized water, stir for reaction, age, solid-liquid separation, dry and calcined, then perform intercalation reaction in hypochlorite solution, and the obtained precipitate is hypochlorite intercalation layered after drying Composite metal hydroxide, this material can be used for the adsorption and removal of arsenic in water, and hypochlorite can be released while adsorbing arsenic, thereby oxidizing organic pollutants in water and killing bacteria. Compared with the prior art, the present invention synthesizes a novel hypochlorite-intercalated layered composite metal hydroxide, which can release hypochlorite while effectively adsorbing arsenic in water, so as to realize the treatment of organic pollutants and bacteria in water. The synergistic removal has the advantages of high utilization efficiency, no need to add additional oxidants, fungicides, etc.

Description

Preparation and application of a hypochlorite intercalated layered composite metal hydroxide

technical field

The invention relates to the field of water treatment, in particular to the preparation and application of a hypochlorite intercalated layered composite metal hydroxide.

Background technique

Arsenic is a toxic and carcinogenic element ubiquitous in nature. Arsenic pollution in drinking water sources is an environmental problem that has attracted global attention. At present, there are arsenic pollution problems in large areas in more than a dozen countries in the world. my country It is also one of the countries with serious arsenic pollution. The arsenic pollution in groundwater and rivers in some areas of my country is very serious. At present, the removal methods of arsenic in water include coagulation, coprecipitation, membrane separation, adsorption and so on. The adsorption method has been widely used in drinking water engineering due to its advantages of cost-effectiveness, high efficiency and convenient operation. At the same time, the surface and groundwater environments in many countries and regions are polluted by organic pollutants, the concentration ranges from ng·L ^-1 to μg·L ^-1 , and changes with geographical location and seasons, such as water drugs and personal Nursing products, endocrine disruptors and other organic pollutants have become a common environmental problem faced by people all over the world. What's more serious is that the combined pollution of arsenic and various organic pollutants has been detected in rivers and lakes used as drinking water sources in many areas of our country. Simultaneous removal of pollutants.

Layered composite metal hydroxides (LDHs) are compounds assembled from positively charged host laminates and interlayer anions through non-covalent interactions. Its structure is similar to brucite Mg(OH) ₂ , and its chemical composition has the following general formula [M ²⁺ _1-x M ³⁺ _x (OH) ₂ ] ^x+ (A ^n- ) _x/n mH ₂ O, where , M ²⁺ and M ³⁺ are divalent and trivalent cations respectively, and X is the molar ratio of trivalent metal cations to the total amount of cations, that is, M ³⁺ /(M ²⁺ +M ³⁺ ). A is an anion between layers, and n is its charge number. Since the interlayer anions of LDHs can ion-exchange with external anions, they can be used for the adsorption and removal of anion pollutants in water in the environmental field. How to apply layered composite metal oxides to the simultaneous removal of organic pollutants and arsenic compound pollution is a topic worthy of research.

Contents of the invention

The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a preparation and application of a hypochlorite intercalated layered composite metal hydroxide with the ability to adsorb arsenic, catalyze the oxidation of organic pollutants and sterilize.

The object of the present invention can be achieved through the following technical scheme: a kind of hypochlorite intercalation layered composite metal hydroxide, the general formula of this hypochlorite intercalation layered composite metal hydroxide is [Mg ²⁺ _0.75 Fe ³⁺ _0.25k Ce ³⁺ _0.25(1-k) (OH) ₂ ] ^0.25+ (ClO ^- ) _0.25 ·mH ₂ O, where k=0.95~1.

A kind of preparation method of hypochlorite intercalation layered composite metal hydroxide as above, described method comprises the following steps:

(1) Mg ²⁺ salt, Ce ³⁺ salt and Fe ³⁺ salt are dissolved in deionized water in proportion to obtain the first solution; NaOH and Na ₂ CO ₃ are mixed and dissolved in deionized water to obtain the second solution; Dissolving hypochlorite in deionized water to obtain a third solution;

(2) The ratio of the sum of the amount of substances of Mg ²⁺ , Ce ³⁺ , and Fe ³⁺ to the amount of NaOH in the second solution is 1: (2～4) Mixing and stirring to obtain a slurry, separating the solid and liquid after aging, washing the solid precipitate to neutrality, drying and calcining to obtain a calcined product;

(3) adding the calcined product into the third solution, performing solid-liquid separation after the reaction, and washing and drying the obtained solid to obtain the hypochlorite-intercalated layered composite metal hydroxide.

The Mg ²⁺ salt is magnesium nitrate or hydrochloride, the Fe ³⁺ salt is iron nitrate or hydrochloride, and the Ce3+ salt is Ce(NO ₃ ) ₃ ·6H ₂ O, so In the above first solution, the concentration of Mg ²⁺ is 150-900mmol·L ^-1 , the ratio of Mg ²⁺ to the total molar concentration of Fe ³⁺ and Ce ³⁺ is 3:1, and Ce ³⁺ accounts for Fe ³⁺ and Ce 3+ ³⁺ 0-5% of the total molar concentration.

In the second solution, the concentration of NaOH is 400˜4800 mmol·L ⁻¹ , and the molar concentration ratio of Na ₂ CO ₃ to NaOH is 0.25:1.

The hypochlorite is NaClO, and the concentration of ClO ^- in the third solution is 20-100 ^{mmol·L -1} .

Keep the pH of the solution at 9-11 during the stirring process described in step (2), so that the metal ions can be completely precipitated.

The aging treatment temperature in step (2) is 60-80°C, the aging time is 20-36h, and the calcination time is 400-500°C, the aging time and temperature are controlled in order to make the precursor have a better Layered structure, calcination at 400-500 °C can keep the laminates of the precursor from collapsing and fully remove the carbonate groups between the layers.

The drying temperature in step (3) is -20 to -10° C. to prevent the decomposition of hypochlorite radicals during the drying process.

The application of the above-mentioned hypochlorite intercalation layered composite metal hydroxide can be used for the adsorption and removal of arsenic in water or the coordinated oxidation degradation of arsenic and organic pollutants.

The organic pollutants include drugs and personal care products, endocrine disruptors or persistent organic pollutants dissolved in water.

When the layered composite metal hydroxide is used to adsorb and remove arsenic and antimony in water and synergistically oxidize and degrade organic pollutants, the layered composite metal hydroxide is added to the water containing arsenic, antimony and organic pollutants , so that the inorganic pollutants in the water are adsorbed on the layered composite metal hydroxide. Since the anion between the laminates of the synthesized material is hypochlorite ion, it has a good ion exchange capacity, so the ability to adsorb pollutants is stronger, and While adsorbing inorganic pollutants such as arsenic and antimony, hypochlorite is replaced by interlayer replacement, which can synergistically kill organic pollutants in water.

Compared with the prior art, the beneficial effects of the present invention are reflected in the following aspects:

(1) The processing sensitivity to arsenic is high;

(2) It can effectively remove compound pollution formed by arsenic and various organic substances, and has a wide range of applications;

(3) The permanganate intercalation layered composite metal hydroxide of the present invention is simple to prepare and low in cost.

detailed description

The embodiments of the present invention are described in detail below. This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating procedures are provided, but the protection scope of the present invention is not limited to the following implementation example.

Example 1

A hypochlorite intercalated layered composite metal hydroxide for synergistically removing composite pollution in water, the preparation method of which comprises the following steps:

(1) Prepare 100ml of the first solution, containing 150mmol·L ^-1 of Mg ²⁺ , 50mmol·L ^-1 of Fe ³⁺ ; prepare another 100ml of the second solution, containing 400mmol·L ^-1 of NaOH and 100mmol·L -1 L ^-1 of Na ₂ CO ₃ ; another 20 mmol·L ^-1 of sodium hypochlorite solution was prepared.

(2) Add the above-mentioned configured first solution and second solution dropwise to a beaker containing 100ml of deionized water at the same time, stir vigorously during the dropwise addition, and control the pH value of the reaction process to remain at 9, and react The obtained slurry was aged at 60°C for 36 hours, and then solid-liquid separation was performed, and the obtained solid precipitate was washed with deionized water until the supernatant was neutral, then dried at 60°C, and calcined at 400°C , The obtained calcined product is added into the sodium hypochlorite solution for reaction.

(3) Centrifuge after the reaction, wash the precipitate with deionized water, and dry at -10°C to obtain the hypochlorite-intercalated layered composite metal hydroxide.

The prepared layered composite metal hydroxide was used for the removal of arsenic in water, and the concentration of arsenic in the water sample containing 1.0mg·L ^-1 pentavalent arsenic was less than 0.01mg·L ^-1 after material adsorption treatment, lower than the national Standard limits for drinking water.

Example 2

A hypochlorite intercalated layered composite metal hydroxide for synergistically removing composite pollution in water, the preparation method of which comprises the following steps:

(1) Prepare 100ml of the first solution containing 900mmol·L ^-1 of Mg ²⁺ , 285mmol·L ^-1 of Fe ³⁺ and 15mmol·L ^-1 of Ce ³⁺ , and prepare 100ml of the second solution containing 4800mmol·L ^-1 of NaOH and 1200mmol·L ^-1 of Na ₂ CO ₃ , and another 100mmol·L ^-1 of sodium hypochlorite solution was prepared.

(2) Add the above-mentioned configured first solution and the second solution dropwise to a beaker containing 100ml of deionized water at the same time, stir vigorously during the dropwise addition, and simultaneously control the pH value of the reaction process to remain at 10. The obtained slurry was aged at 70°C for 24 hours, and then solid-liquid separation was performed, and the obtained solid precipitate was washed with deionized water until the supernatant was neutral, then dried at 60°C, and calcined at 500°C , The obtained calcined product is added into the sodium hypochlorite solution for reaction.

(3) Centrifuge after the reaction, wash the precipitate with deionized water, and dry at -20°C to obtain the hypochlorite-intercalated layered composite metal hydroxide.

The prepared layered composite metal hydroxide is used for the removal of arsenic in water. For water samples containing 0.5mg·L ^-1 pentavalent arsenic and 0.5mg·L ^-1 trivalent arsenic, the total arsenic after material adsorption treatment The concentration is less than 0.01mg·L ^-1 , lower than the national drinking water standard limit.

Example 3

A hypochlorite intercalated layered composite metal hydroxide for synergistically removing composite pollution in water, the preparation method of which comprises the following steps:

(1) Prepare 100ml of the first solution containing 300mmol·L ^-1 of Mg ²⁺ , 95mmol·L ^-1 of Fe ³⁺ and 5mmol·L ^-1 of Ce ³⁺ , and prepare 100ml of the second solution containing 800mmol·L ^-1 of NaOH and 200mmol·L ^-1 of Na ₂ CO ₃ , and another 100mmol·L ^-1 of sodium hypochlorite solution was prepared.

(2) Add the above-mentioned configured first solution and second solution dropwise to a beaker containing 100ml of deionized water at the same time, stir vigorously during the dropwise addition, and simultaneously control the pH value of the reaction process to remain at 11, and react The obtained slurry was aged at 80°C for 20 hours, and then solid-liquid separation was performed, and the obtained solid precipitate was washed with deionized water until the supernatant was neutral, then dried at 60°C, and calcined at 500°C , The obtained calcined product is added into the sodium hypochlorite solution for reaction.

(3) Centrifuge after the reaction, wash the precipitate with deionized water, and vacuum freeze-dry at -10°C to obtain the hypochlorite-intercalated layered composite metal hydroxide.

The prepared layered composite metal hydroxide is used to purify water containing arsenic and organic pollutants. For water samples containing 0.5 mg·L ^-1 pentavalent arsenic, the concentration of total arsenic after material adsorption treatment is less than 0.01 mg· L ^-1 , lower than the national drinking water standard limit, the released hypochlorite can oxidize organic pollutants.

Example 4

A hypochlorite intercalated layered composite metal hydroxide for synergistically removing composite pollution in water, the preparation method of which comprises the following steps:

(1) Prepare 100ml of the first solution containing 600mmol·L ^-1 of Mg ²⁺ , 190mmol·L ^-1 of Fe ³⁺ and 10mmol·L ^-1 of Ce ³⁺ , and prepare 100ml of the second solution containing 1600mmol·L ^-1 of NaOH and 400mmol·L ^-1 of Na ₂ CO ₃ , and another 100mmol·L ^-1 of sodium hypochlorite solution was prepared.

(2) Add the above-mentioned configured first solution and the second solution dropwise to a beaker containing 100ml of deionized water at the same time, stir vigorously during the dropwise addition, and control the pH value of the reaction process to remain at 10.5, and react The obtained slurry was aged at 70°C for 36 hours, and then solid-liquid separation was performed, and the obtained solid precipitate was washed with deionized water until the supernatant was neutral, then dried at 60°C, and calcined at 500°C , The obtained calcined product is added into the sodium hypochlorite solution for reaction.

(3) Centrifuge after the reaction, wash the precipitate with deionized water, and dry at -10°C to obtain the hypochlorite-intercalated layered composite metal hydroxide.

The prepared layered composite metal hydroxide is used to purify water containing arsenic and trace organic pollutants and bacteria. Water samples containing 1.0mg·L ^-1 pentavalent arsenic, trace organic pollutants and bacteria are adsorbed by the material The concentration of total arsenic after treatment is less than 0.01mg·L ^-1 , which is lower than the national drinking water standard limit, and the released hypochlorite can oxidize organic pollutants in water and kill bacteria.

Example 5

A hypochlorite intercalated layered composite metal hydroxide for synergistically removing composite pollution in water, the preparation method of which comprises the following steps:

(1) Prepare 100ml of the first solution, containing 450mmol·L ^-1 of Mg ²⁺ , 142.5mmol·L ^-1 of Fe ³⁺ and 7.5mmol·L ^-1 of Ce ³⁺ , and prepare 100ml of the second solution , containing 1200mmol·L ^-1 NaOH and 300mmol·L ^-1 Na ₂ CO ₃ , and another 100mmol·L ^-1 sodium hypochlorite solution was prepared.

(2) Add the above-mentioned configured first solution and second solution dropwise to a beaker containing 100ml of deionized water at the same time, stir vigorously during the dropwise addition, and control the pH value of the reaction process to remain at 9.5, and react The obtained slurry was aged at 80°C for 24 hours, and then solid-liquid separation was performed, and the obtained solid precipitate was washed with deionized water until the supernatant was neutral, then dried at 60°C, and calcined at 500°C , The obtained calcined product is added into the sodium hypochlorite solution for reaction.

(3) Centrifuge after the reaction, wash the precipitate with deionized water, and dry at -10°C to obtain the hypochlorite-intercalated layered composite metal hydroxide.

The prepared layered composite metal hydroxide is used to purify water containing arsenic, trace organic pollutants, and bacteria. Water samples containing 0.5mg·L ^-1 pentavalent arsenic, trace organic pollutants, and bacteria are adsorbed by the material The concentration of total arsenic after treatment is less than 0.01mg·L ^-1 , which is lower than the national drinking water standard limit, and the released hypochlorite can oxidize organic pollutants in water and kill bacteria.

Example 6

A hypochlorite intercalated layered composite metal hydroxide for synergistically removing composite pollution in water, the preparation method of which comprises the following steps:

(1) Prepare 100ml of the first solution containing 100mmol·L ^-1 of Mg ²⁺ , 285mmol·L ^-1 of Fe ³⁺ and 15mmol·L ^-1 of Ce ³⁺ , and prepare 100ml of the second solution containing 900mmol·L ^-1 of NaOH and 900mmol·L ^-1 of Na ₂ CO ₃ , and another 100mmol·L ^-1 of sodium hypochlorite solution was prepared.

(2) Add the above-mentioned configured first solution and second solution dropwise to a beaker containing 100ml of deionized water at the same time, stir vigorously during the dropwise addition, and control the pH value of the reaction process to remain at 9, and react The obtained slurry was aged at 65°C for 24 hours, and then solid-liquid separation was performed, and the obtained solid precipitate was washed with deionized water until the supernatant was neutral, then dried at 60°C, and calcined at 500°C , The obtained calcined product is added into the sodium hypochlorite solution for reaction.

(3) Centrifuge after the reaction, wash the precipitate with deionized water, and dry at -10°C to obtain the hypochlorite-intercalated layered composite metal hydroxide.

The prepared layered composite metal hydroxide is used to purify water containing arsenic and trace organic pollutants and bacteria. Water samples containing 0.8 mg·L ^-1 pentavalent arsenic, trace organic pollutants and bacteria are adsorbed by the material The concentration of total arsenic after treatment is less than 0.01mg·L ^-1 , which is lower than the national drinking water standard limit, and the released hypochlorite can oxidize organic pollutants in water and kill bacteria.

Claims (9)

1. a kind of preparation method of hypochlorite intercalation layered composite metal hydroxides, it is characterised in that methods described includes Following steps：

(1) by Mg²⁺Salt, Ce³⁺Salt and Fe³⁺Salt is dissolved in deionized water in proportion, obtains the first solution；By NaOH and Na₂CO₃It is mixed Merging, which is dissolved in deionized water, obtains the second solution；Hypochlorite is dissolved in deionized water, the 3rd solution is obtained；

(2) the first solution and the second solution are pressed into Mg²⁺、Ce³⁺、Fe³⁺Material amount sum and the second solution in NaOH thing The ratio between amount of matter is 1：(2~4) are mixed, and stirring obtains separation of solid and liquid after slurries, ageing, and by solid sediment clean to Neutrality, dries and calcines, obtain calcined product；

(3) calcined product is added into the 3rd solution, separation of solid and liquid is carried out after reaction, obtained solid is cleaned and done It is dry, produce the hypochlorite intercalation layered composite metal hydroxides.

2. a kind of preparation method of hypochlorite intercalation layered composite metal hydroxides according to claim 1, it is special Levy and be, the Mg²⁺Salt is the nitrate or hydrochloride of magnesium, the Fe³⁺Salt is the nitrate or hydrochloride of iron, the Ce3+ Salt is Ce (NO₃)₃·6H₂In O, first solution, Mg²⁺Concentration be 150~900mmolL^-1, Mg²⁺With Fe³⁺And Ce³⁺ The ratio of total mol concentration is 3:1, Ce³⁺Account for Fe³⁺And Ce³⁺The 0~5% of total mol concentration.

3. a kind of preparation method of hypochlorite intercalation layered composite metal hydroxides according to claim 1, it is special Levy and be, in second solution, NaOH concentration is 400~4800mmolL^-1, Na₂CO₃Molar concentration rate with NaOH is 0.25:1。

4. a kind of preparation method of hypochlorite intercalation layered composite metal hydroxides according to claim 1, it is special Levy and be, the hypochlorite is ClO in NaClO, the 3rd solution^-Concentration be 20~100mmolL^-1。

5. a kind of preparation method of hypochlorite intercalation layered composite metal hydroxides according to claim 1, it is special Levy and be, keep pH value of solution to be 9~11 in whipping process described in step (2).

6. a kind of preparation method of hypochlorite intercalation layered composite metal hydroxides according to claim 1, it is special Levy and be, the treatment temperature of step (2) described ageing is 60~80 DEG C, and digestion time is 20~36h, and the calcination time is 400~500 DEG C.

7. a kind of preparation method of hypochlorite intercalation layered composite metal hydroxides according to claim 1, it is special Levy and be, step (3) described drying temperature is -20~-10 DEG C.

8. one kind is using the hypochlorite intercalation layered composite metal hydroxides as obtained by claim 1~7 any methods described Application, it is characterised in that the hypochlorite intercalation layered composite metal hydroxides are used for the absorption of arsenic element in water and gone Remove or the synergistic oxidation of arsenic element and organic pollution is degraded.

9. a kind of application of hypochlorite intercalation layered composite metal hydroxides according to claim 8, its feature exists In the organic pollution includes medicine soluble in water and personal care articles, incretion interferent or persistency organic contaminant Thing.