CN106166474B

CN106166474B - A method for specific regulation of nano-zero-valent iron corrosion products and enhanced nano-zero-valent iron adsorption of low-concentration arsenic

Info

Publication number: CN106166474B
Application number: CN201610678897.2A
Authority: CN
Inventors: 林璋; 吴�灿; 刘炜珍; 党志; 石振清
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2016-08-17
Filing date: 2016-08-17
Publication date: 2019-05-14
Anticipated expiration: 2036-08-17
Also published as: CN106166474A

Abstract

The invention discloses a kind of specific regulatory control nano zero valence iron corrosion product and reinforce the method for nano zero valence iron adsorption of Low Concentration arsenic.NZVI@Mg (OH) is made by the way that nano zero valence iron is carried on magnesium hydroxide surface in this method₂Composite material, reaches the regulation of nano zero valence iron corrosion product, while enhancing absorption of the nano zero valence iron to low-concentration arsenic.The method of the present invention is simple to operation, and raw material sources are extensive, low in cost.NZVI@Mg (OH) obtained₂Composite material sufficiently amplifies single nZVI or Mg (OH)₂As in water body (V) concentration effectively can be down to drinking water standard, also have higher adsorption capacity to As (V) by the advantages of material.

Description

A kind of specific regulatory control nano zero valence iron corrosion product simultaneously reinforces nano zero valence iron absorption The method of low-concentration arsenic

Technical field

The invention belongs to the arsenic adsorption technology field in wastewater treatment, it is related to through load nano zero valence iron to magnesium hydroxide Surface generates and enhances the method that nano zero valence iron adsorbs low-concentration arsenic to control nano zero valence iron corrosion product.

Background technique

Arsenic is that a kind of element being widely present, inorganic compound have severe toxicity in nature.Arsenic acid is because of and phosphoric acid molecules Model is similar, can inhibit phosphatic oxidation, to block the main energy metabolism system of life entity.Long Term Contact or It is exposed to cause the multiple organs of human body and lesion tissue or carcinogenic in containing the exceeded environment of arsenic.Drinking water is asked containing arsenic is exceeded Topic worldwide influences extensively, Bangladesh, Chile, China, Hungary, India, Mexico, Rome Leah, Vietnam, beauty Successively there is the different degrees of drinking water report exceeded containing arsenic in the countries and regions such as state.In addition, it is worth noting that, underground water The pollution of arsenic is a kind of typical low concentration pollution problem, and most countries underground water arsenic concentration is all in 0 ~ 5200 μ g/L range It is interior.In order to reduce harm of the arsenic to human health, in 1993, drinking water standard was lowered to containing arsenic concentration by 50 μ g/L by WHO 10 μg/L。

Currently, the removal most common method of arsenic in water body is absorption method.Nano zero valence iron (nZVI) because its bigger serface, High reaction activity, to arsenic high-adsorption-capacity and easy Magnetic Isolation the features such as and by pro-gaze, become wide in removing arsenic in water research For the material of concern.Stable nZVI specific grain surface product can reach 40m²/ g or more, reaction rate is than micron Zero-valent Iron ZVI high 1000 times or more, maximum adsorption capacity is that 3.5mg/g(initial concentration is 1mg/L^-1).However nZVI because it is easy to reunite, unstable with And intensity difference and be subject to certain restrictions its adsorption capacity.In order to overcome these limitations, nZVI is loaded to other porous materials Material, such as active carbon, chitosan-carboxymethyl β-cyclodextrin, chitosan nano microballoon and montmorillonite.So And the research about NZVI composite material arsenic removal performance, the adsorption capacity for improving composite material is had focused largely on, is often but ignored Water quality requirement after actual environmental problem or processing.Processing water body is significantly larger than actual concentrations in environment containing arsenic concentration, WHO drinking water standard is not achieved in adsorption equilibrium concentration.In addition, nZVI is easily corroded in aerobic environment, corrosion product Including magnetic iron ore/maghemite and lepidocrocite.Studies have shown that it is red that As (V) is preferentially adsorbed on magnetic iron ore/magnetic compared with lepidocrocite Iron ore surface.If can change the reaction condition of nZVI, control its corrosion product for reaching specificity is changed into the red iron of magnetic iron ore/magnetic Mine can then enhance nZVI to the adsorption capacity of As (V).However but have no the research report of this respect.

Summary of the invention

It is an object of that present invention to provide a kind of specific regulatory control nano zero valence iron corrosion product and reinforce nano zero valence iron suction The method of attached low-concentration arsenic.The present invention is by being loaded to magnesium hydroxide surface for nano zero valence iron to regulate and control nano zero-valence iron rot The generation of product, while enhancing absorption of the nano zero valence iron to low-concentration arsenic above-mentioned is asked with solve in the presence of the prior art Topic.

For achieving the above object, the technical solution adopted by the present invention is as follows.

A kind of specific regulatory control nano zero valence iron corrosion product and the method for reinforcing nano zero valence iron adsorption of Low Concentration arsenic, packet Include following steps:

(1) Mg (OH) is configured₂Suspension: by Mg (OH)₂It is dissolved in dehydrated alcohol, ultrasonic disperse obtains Mg (OH)₂Suspension；

(2) Fe is configured₂SO₄Solution: by Fe₂SO₄∙7H₂O is dissolved in deionized water, obtains Fe₂SO₄Solution；

(3) NaBH is configured₄Solution: by NaBH₄Solid is dissolved in deionized water, obtains NaBH₄Solution；

(4) Mg (OH) is taken₂Suspension is placed in three-necked flask, keeps mechanical stirring, is passed through inert gas insulation blocking, is added Fe₂SO₄Solution, and NaBH is added dropwise with the speed of 3mL/min immediately₄Solution；

(5) after being added dropwise to complete, it is centrifugally separating to obtain black solid, is washed, is dried to get nZVI@Mg (OH) is arrived₂It is compound Material；

(6) it takes As (V) solution in vial at room temperature, adjusts PH with HCl solution and NaOH solution, be added step (5) NZVI@Mg (OH) obtained₂Composite material is placed in constant temperature oscillator and at the uniform velocity vibrates, and solid-liquid sample, test are separated after oscillation As (V) content in solution.

Further, in step (1), the time of the ultrasonic disperse is 5min.

Further, the Mg (OH)₂The concentration of suspension is 0.1mol/L.

Further, the Fe₂SO₄The concentration of solution is 0.1mol/L.

Further, the NaBH₄The concentration of solution is 0.25mol/L.

Further, churned mechanically rate described in step (4) is 300 r/min, and mechanical stirring is kept to NaBH₄It is molten Liquid completion of dropwise addition.

Further, inert gas described in step (4) includes nitrogen or argon gas.

Further, in step (4), the molar ratio of reactant additive amount is Mg (OH)₂: Fe₂SO₄: NaBH₄ =1:1:2。

Further, in step (5), the washing refers to successively is cleaned 3 times with dehydrated alcohol and deionized water.

Further, in step (5), the drying is the lower 45 DEG C of dryings of vacuum.

Further, in step (6), the concentration of As (V) solution is 1 ~ 8 mg/L.

Further, in step (6), the concentration of the HCl solution and NaOH solution is 0.1 mol/L.

Further, in step (6), the value of the pH is 7.0 ± 0.25.

Further, in step (6), the nZVI@Mg (OH)₂The additive amount of composite material is 0.1 g/L.

Further, in step (6), hunting speed is 200 r/min, and duration of oscillation is 6 h.

Mechanism of the invention is: nZVI is loaded to Mg (OH)₂Process use liquid phase reduction, nZVI is in aerobic environment In be easily corroded, corrosion product includes magnetic iron ore/maghemite and lepidocrocite.Studies have shown that compared with lepidocrocite, As (V) It is preferentially adsorbed on magnetic iron ore/maghemite surface.The corrosion product of nano zero valence iron in the solution is mainly lepidocrocite, is also contained A small amount of magnetic iron ore/maghemite.And after nano zero valence iron is loaded to magnesium hydroxide surface, since magnesium hydroxide is slightly soluble in water, In nano zero valence iron corrosion process, magnesium hydroxide releases OH as a kind of solid base, continuous dissolution^-, to make nanometer Magnetic iron ore/maghemite content increases in the corrosion product of Zero-valent Iron, and the content of lepidocrocite is reduced.And magnetic iron ore/magnetic is red Iron ore is better than lepidocrocite to the adsorption capacity of arsenic, so that nano zero valence iron enhances the adsorption capacity of arsenic.If can change The reaction condition of nZVI and As (V) solution, control its corrosion product for reaching specificity are changed into magnetic iron ore/maghemite, from And enhance nZVI to the adsorption capacity of As (V).

It is shown experimentally that, Mg (OH)₂As in water body (V) concentration can be down to drinking water standard, but adsorption capacity is small； NZVI is big to As (V) adsorption capacity, but the As (V) in solution can not be effectively reduced in low concentration；Prepared by nZVI@ Mg(OH)₂Composite material then combines the advantages of the two, As in water body (V) concentration effectively can be down to drinking water standard, right As (V) also has higher adsorption capacity.

Compared with prior art, the invention has the advantages that and technical effect:

(1) the method for the present invention is simple, easy to operate, easily controllable under room temperature；

(2) raw material sources of the present invention are extensive, low in cost；

(3) the advantages of sufficiently amplifying homogenous material, makes to make the best use of everything, obtained nZVI@Mg (OH)₂Composite material can be both As in water body (V) concentration effectively can be down to drinking water standard, also have higher adsorption capacity to As (V).

Detailed description of the invention

Fig. 1 is nZVI@Mg (OH) obtained₂Equilibrium concentration compares after composite material and homogenous material processing low-concentration arsenic.

Specific embodiment

The invention will be further described combined with specific embodiments below, but protection scope of the present invention is not only limited to reality Apply example.

Mg(OH)₂It is synthesized by chemical precipitation method: under room temperature, the NaOH aqueous solution of 1M being added dropwise in equal volume dropwise 0.5M MgSO₄In solution, it is added dropwise and is vigorously stirred simultaneously with the speed of 300 r/min, wherein MgSO₄Solution passes through dissolution MgSO₄∙7H₂It is obtained in the glycerol aqueous solvent of O to 85wt%.After being added dropwise to complete, continuing to stir 6h, standing is centrifugated afterwards for 24 hours, It is successively cleaned 3 times with deionized water and dehydrated alcohol, 45 DEG C of dryings are spare.

Arsenic removal experiment carries out in 25ml vial: take As (V) solution that 20ml concentration is 1 ~ 8 mg/L in vial, PH to 7.0 ± 0.25 is adjusted with 0.1 M HCl solution and 0.1M NaOH solution, nZVI@Mg made from 0.1 g/L is added (OH)₂Composite material is placed in constant temperature oscillator and is at the uniform velocity vibrated with 200 r/min, taken out after 6h, by supernatant liquor through 0.45 μm of mistake Membrane filtration measures As content.

Embodiment 1

(1) Mg (OH) of 0.1 mol/L is configured₂Suspension: by Mg (OH)₂It is dissolved in dehydrated alcohol, ultrasonic disperse 5min is obtained To the Mg (OH) of 0.1 mol/L₂Suspension；

(2) Fe of 0.1 mol/L is configured₂SO₄Solution: by Fe₂SO₄∙7H₂O is dissolved in deionized water, obtains 0.1mol/L's Fe₂SO₄Solution；

(3) NaBH of 0.25 mol/L is configured₄Solution: by NaBH₄Solid is dissolved in deionized water, obtains 0.25mol/L's NaBH₄Solution；

(4) Mg (OH) of 75 ml0.1 mol/L is taken₂Suspension liquid is placed in 500ml three-necked flask, keeps mechanical stirring 300 r/min are passed through nitrogen insulation blocking, and the Fe of 75 ml, 0.1 mol/L is added₂SO₄Solution, and immediately with 3 mL/min's The NaBH of 0.25 mol/L is added dropwise in speed₄Solution 60ml；

(5) after being added dropwise to complete, centrifuge separation gained black solid, dehydrated alcohol and deionized water successively clean 3 times, and 45 DEG C vacuum drying to get arrive nZVI@Mg (OH)₂Composite material；

(6) at normal temperature, take As (V) solution that 20ml concentration is 1mg/L in vial, it is molten with the HCl of 0.1mol/L Liquid and 0.1mol/L NaOH solution adjust PH to 7.0, and nZVI@Mg (OH) made from 0.1g/L is added₂Composite material is placed in perseverance Warm oscillator is at the uniform velocity vibrated with 200 r/min, and As (V) concentration is down to 3 μ g/L in solution after 6h；It is more unsupported than nZVI to Mg (OH)₂When residual concentration (18.7 μ g/L) it is low；nZVI@Mg(OH)₂Composite material is 0.996 mg/g to the adsorption capacity of arsenic, and Nano zero valence iron adsorption capacity is then 0.981 mg/g, and adsorption of magnesium hydroxide capacity is then 0.992 mg/g.

Embodiment 2

Step (1)-(5) are same as Example 1；

Arsenic removal experiment:

At normal temperature, take As (V) solution that 20 ml concentration are 5 mg/L in vial, with the HCl solution of 0.1 mol/L PH to 7.0 is adjusted with 0.1mol/L NaOH solution, nZVI@Mg (OH) made from 0.1 g/L is added₂Composite material is placed in constant temperature Oscillator is at the uniform velocity vibrated with 200 r/min, nZVI@Mg (OH) after 6 h₂Composite material is 4.94 to the adsorption capacity of As (V) mg/g；And nano zero valence iron adsorption capacity is then 4.57 mg/g, and adsorption of magnesium hydroxide capacity is then 3.04 mg/g.

Embodiment 3

Step (1)-(5) are same as Example 1；

Arsenic removal experiment:

At normal temperature, take As (V) solution that 20 ml concentration are 8 mg/L in vial, with the HCl solution of 0.1 mol/L PH to 7.0 is adjusted with 0.1mol/L NaOH solution, nZVI@Mg (OH) made from 0.1 g/L is added₂Composite material is placed in constant temperature Oscillator is at the uniform velocity vibrated with 200 r/min, nZVI@Mg (OH) after 6 h₂Composite material is 6.75 to the adsorption capacity of As (V) mg/g；And Zero-valent Iron adsorption capacity is then 6.68 mg/g, and adsorption of magnesium hydroxide capacity is then 3.50 mg/g.

Fig. 1 is nZVI@Mg (OH) obtained₂Composite material and single nZVI or Mg (OH)₂Material processing low concentration water body In As (V) afterwards equilibrium concentration compare.As shown in Figure 1, when As (V) initial concentration is gradually lowered to 1 mg/L by 8 mg/L, Equilibrium concentration gradually decreases.Relative to nZVI and Mg (OH)₂Individually effect when absorption, nZVI@Mg (OH)₂Composite material beginning table Reveal best arsenic-adsorbing ability.In addition as shown in black arrow on the way, when As (V) initial concentration is 1 mg/L, nZVI@Mg (OH)₂Equilibrium concentration corresponding to composite material is 3.60 μ g/L, is lower than 10 μ g/L of World Health Organization's drinking water standard.Show multiple As in water body (V) content effectively can be reduced to drinking water standard by condensation material.

Be it is necessary to described herein finally: above embodiments are served only for making technical solution of the present invention further detailed Ground explanation, should not be understood as limiting the scope of the invention, those skilled in the art's above content according to the present invention The some nonessential modifications and adaptations made all belong to the scope of protection of the present invention.

Claims

1. a specific control nanometer zerovalent iron corrosion product and strengthen the method for nanometer zerovalent iron adsorption low-concentration arsenic, is characterized in that, comprises the steps:

(1) Configure Mg(OH) ₂ suspension: Dissolve Mg(OH) ₂ in absolute ethanol, and ultrasonically disperse to obtain Mg(OH) ₂ suspension;

(2) Prepare FeSO ₄ solution: Dissolve FeSO ₄ ∙7H ₂ O in deionized water to obtain FeSO ₄ solution;

(3) Configure NaBH ₄ solution: Dissolve NaBH ₄ solid in deionized water to obtain NaBH ₄ solution;

(4) Take the Mg(OH) ₂ suspension and place it in a three-necked flask, keep mechanical stirring, introduce inert gas for isolation protection, add FeSO ₄ solution, and immediately add NaBH ₄ solution dropwise at a speed of 3 mL/min;

(5) After the dropwise addition is completed, centrifuge to obtain a black solid, wash and dry to obtain the nZVI@Mg(OH) ₂ composite material;

(6) Take the As(V) solution in a glass bottle at room temperature, the concentration of the As(V) solution is 1~8 mg/L, adjust the pH with HCl solution and NaOH solution, and add the solution obtained in step (5). The nZVI@Mg(OH) ₂ composite material was placed in a constant-temperature oscillator to oscillate at a constant speed. After the oscillation, the solid-liquid samples were separated, and the As(V) content in the solution was tested.

2. A method for specifically regulating nano-zero-valent iron corrosion products and enhancing nano-zero-valent iron adsorption of low-concentration arsenic according to claim 1, wherein the ultrasonic dispersion time in step (1) is 5min .

3. a kind of specific regulation nano-zero-valent iron corrosion product according to claim 1 and strengthen the method for nano-zero-valent iron adsorption low-concentration arsenic, it is characterised in that the Mg(OH) _The concentration of the suspension is 0.1 mol/L; the concentration of the FeSO ₄ solution is 0.1 mol/L; the concentration of the NaBH ₄ solution is 0.25 mol/L.

4. A method for specifically regulating nano-zero-valent iron corrosion products and enhancing nano-zero-valent iron adsorption of low-concentration arsenic according to claim 1, wherein the speed of the mechanical stirring in step (4) is 300 r/min, mechanical stirring was maintained until the end of the dropwise addition of the NaBH ₄ solution; the inert gas included nitrogen or argon.

5 . A method for specifically regulating nano-zero-valent iron corrosion products and enhancing nano-zero-valent iron adsorption of low-concentration arsenic according to claim 1, wherein in step (4), the molar ratio of the added amount of reactants is It is Mg(OH) ₂ : FeSO ₄ : NaBH ₄ =1:1:2.

6. A method for specifically regulating nano-zero-valent iron corrosion products and enhancing nano-zero-valent iron adsorption of low-concentration arsenic according to claim 1, characterized in that, in step (5), the washing refers to using non- Water ethanol and deionized water were successively washed 3 times; the drying was drying at 45°C under vacuum.

7. The method for specifically regulating nano-zero-valent iron corrosion products and enhancing nano-zero-valent iron adsorption of low-concentration arsenic according to claim 1, wherein in step (6), the HCl solution and the NaOH solution The concentration of the pH was 0.1 mol/L; the pH value was 7.0±0.25.

8. A method for specifically regulating nano-zero-valent iron corrosion products and enhancing nano-zero-valent iron adsorption of low-concentration arsenic according to claim 1, wherein in step (6), the nZVI@Mg(OH) ) ₂ The additive amount of the composite material is 0.1 g/L.

9 . The method for specifically regulating nano-zero-valent iron corrosion products and enhancing nano-zero-valent iron adsorption of low-concentration arsenic according to claim 1, wherein in step (6), the oscillation speed is 200 r/min, the oscillation time is 6h.