阅读说明：本技术 一种电辅助Fe-MOF材料催化处理重金属-EDTA络合物废水的方法 (Method for catalytically treating heavy metal-EDTA complex wastewater by using electrically-assisted Fe-MOF material ) 是由 雷永乾 张悦 郭鹏然 郭子维 于 2021-06-30 设计创作，主要内容包括：本发明公开了一种电辅助Fe-MOF材料催化处理重金属-EDTA络合物废水的方法,以Fe-MOF材料为非均相催化剂,通过电辅助激活过硫酸盐,高效可持续破解重金属-EDTA络合物,解决均相体系产生大量铁泥影响后续处理的问题；通过施加电流,使Fe-MOF上具有催化活性的Fe(Ⅱ)能通过阴极上的还原反应持续再生,提高催化剂的利用率和可再生性；使用过二硫酸盐(PDS)代替芬顿体系中的H-(2)O-(2)作为氧化剂,氧化能力更强,pH适用范围更广,不需要对仪器设备的耐酸耐腐蚀性有高要求,解决了目前重金属络合废水芬顿技术存在的问题。(The invention discloses a method for treating heavy metal-EDTA complex wastewater by electrically-assisted Fe-MOF material catalysis, which takes Fe-MOF material as a heterogeneous catalyst, activates persulfate by electric assistance, effectively and sustainably breaks heavy metal-EDTA complex, and solves the problem that a homogeneous system generates a large amount of iron mud to influence subsequent treatment; by applying current, Fe (II) with catalytic activity on the Fe-MOF can be continuously regenerated through reduction reaction on a cathode, so that the utilization rate and the reproducibility of the catalyst are improved; replacement of H in Fenton's system by Peroxydisulfate (PDS) 2 O 2 As an oxidant, the oxidation capacity is stronger, the pH application range is wider, high requirements on acid resistance and corrosion resistance of instruments and equipment are not required, and the problem of the Fenton technology of the heavy metal complex wastewater at present is solved.)

1. A method for catalytically treating heavy metal-EDTA complex wastewater by using an electrically-assisted Fe-MOF material is characterized by comprising the following steps of: the heterogeneous solid catalyst Fe-MOF and the peroxodisulfate are added to an electrochemical reactor containing the wastewater containing the heavy metal-EDTA complex, Na₂SO₄As electrolytes, peroxodisulfates, heavy metal-EDTA complexes and Na₂SO₄The mixture ratio of (0.5-8): (0.4-1): (5-80), adjusting the initial pH to 3-12, arranging electrodes at two ends of the reaction container and connecting with a direct current power supply, treating for 60-100min, and controlling the current density to 1.90-5.71mA/cm²And the cathode and the anode of the electrode are graphite plate electrodes.

2. The method for catalytically treating the wastewater containing the heavy metal-EDTA complex by the electrically assisted Fe-MOF material according to claim 1, wherein the free heavy metal ions after the complex breaking are reduced on the cathode to form heavy metal deposits.

3. The method for catalytically treating the heavy metal-EDTA complex wastewater by using the electrically-assisted Fe-MOF material according to claim 1 or 2, wherein the heavy metal-EDTA complex is one of Cu-EDTA, Pb-EDTA, Ni-EDTA and Cd-EDTA.

4. Method for the catalytic treatment of heavy metal-EDTA complex wastewater by an electrically assisted Fe-MOF material according to claim 1 or 2, characterized in thatThen, the adding amount of Fe-MOF is 0.2-1.2 g/L; the adding amount of the peroxydisulfate is 0.5-8 mmol/L; the concentration of the heavy metal-EDTA complex in the wastewater is 0.4-1.0 mmol/L; na (Na)₂SO₄The concentration is 0.005-0.08 mol/L.

5. The method for the catalytic treatment of the heavy metal-EDTA complex wastewater by the electrically-assisted Fe-MOF material according to claim 1 or 2, wherein the heterogeneous solid catalyst Fe-MOF is prepared by a microwave method, and the specific preparation method comprises the following steps: weighing the mixture with a molar ratio of 1.5: FeSO of (1-2)₄·7H₂Fully grinding O and trimesic acid in an agate mortar, dissolving in 0.01mol/L diluted NaOH solution, performing ultrasonic mixing for 20min to obtain a mixed solution, and FeSO in the mixed solution₄·7H₂The molar concentration of O is 0.053-0.107mol/L, the mixed solution is transferred to a microwave digestion instrument and reacts for 10-20min at the temperature of 180-; and after the solution is cooled, washing with absolute ethyl alcohol and deionized water, and carrying out vacuum drying at 70 ℃ for 12h to obtain the heterogeneous solid catalyst Fe-MOF.

The technical field is as follows:

the invention relates to the technical field of wastewater treatment, in particular to a method for treating heavy metal-EDTA complex wastewater by electrically-assisted Fe-MOF material catalysis.

Background art:

EDTA (ethylene diamine tetraacetic acid) is widely applied to the chemical copper plating and the electroplating process of printed circuit boards, can be bonded with a plurality of heavy metal ions such as copper, nickel, cadmium, lead, zinc and the like through 3 or 4-COOH and 2 nitrogen atoms to form a complex with strong stability and a plurality of five-membered rings as a strong complexing agent, has the characteristics of difficult biodegradation, high solubility, stable structure and the like, and is harmful to human health and ecological environment.

The current practical process for degrading the heavy metal-EDTA complex is roughly divided into two modes of breaking and not breaking the complex. The main purposes of processes such as chemical precipitation, adsorption, chemical replacement and the like are not to break the complex, the content of heavy metal is reduced, the structure of an organic ligand is not damaged, and residual EDTA can be used for re-complexing heavy metal in water in subsequent urban pipe network treatment or natural water body to cause secondary pollution. Therefore, the realization of the complex breaking of the heavy metal-EDTA complex becomes the development key point of the heavy metal complex wastewater treatment. The Fenton method (Fenton) is a complex breaking method widely applied to actual metal complex wastewater at present, and breaks a complex structure by generating a free radical with strong oxidizing property to fundamentally degrade a metal complex, but the Fenton method applied to heavy metal complex wastewater treatment at present has the following problems: 1. the paint is only suitable for acid conditions, and has high requirements on acid resistance and corrosion resistance of instruments and equipment; 2. a large amount of iron salt is consumed as a catalyst; 3. and simultaneously, iron mud is generated and needs secondary treatment.

The invention content is as follows:

the invention aims to provide a method for treating heavy metal-EDTA complex wastewater by electrically-assisted Fe-MOF material catalysis, which takes Fe-MOF (iron-based metal organic framework) material as a heterogeneous catalyst, activates Peroxydisulfate (PDS) by electric assistance, efficiently and sustainably breaks heavy metal-EDTA complex, and solves the problem that a homogeneous system generates a large amount of iron mud to influence subsequent treatment; by applying current, Fe (II) with catalytic activity on the Fe-MOF can be continuously regenerated through reduction reaction on a cathode, so that the utilization rate and the reproducibility of the catalyst are improved; using Peroxodisulfate (PDS) instead ofH in the Fenton System₂O₂As an oxidant, the oxidation capacity is stronger, the pH application range is wider, high requirements on acid resistance and corrosion resistance of instruments and equipment are not required, and the problem of the Fenton technology of the heavy metal complex wastewater at present is solved.

The invention is realized by the following technical scheme:

a method for catalytically treating heavy metal-EDTA complex wastewater by using an electrically-assisted Fe-MOF material, comprising the following steps: adding heterogeneous solid catalyst Fe-MOF and oxidant peroxodisulfate (PDS for short) into an electrochemical reactor filled with wastewater containing heavy metal-EDTA complex, and adding Na₂SO₄As electrolytes, peroxodisulfates, heavy metal-EDTA complexes and Na₂SO₄The mixture ratio of (0.5-8): (0.4-1): (5-80), adjusting the initial pH to 3-12, arranging electrodes at two ends of the reaction container and connecting with a direct current power supply, treating for 60-100min, and controlling the current density to 1.90-5.71mA/cm²And the cathode and the anode of the electrode are graphite plate electrodes, and the heavy metal-EDTA complex is efficiently decomposed by advanced oxidation under normal temperature through an electrically-assisted Fe-MOF catalyst.

The free heavy metal ions after the complex breaking are reduced on the cathode to form heavy metal deposition so as to achieve the recovery effect.

The heavy metal-EDTA complex is one of Cu-EDTA, Pb-EDTA, Ni-EDTA and Cd-EDTA.

The dosage of the heterogeneous solid catalyst Fe-MOF is 0.2-1.2 g/L; the dosage of the PDS oxidant is 0.5-8 mmol/L; the concentration of the heavy metal-EDTA complex in the wastewater is 0.4-1.0 mmol/L; na (Na)₂SO₄The concentration is 0.005-0.08 mol/L.

The heterogeneous solid catalyst Fe-MOF is prepared by a microwave method, and the specific preparation method comprises the following steps: weighing the mixture with a molar ratio of 1.5: FeSO of (1-2)₄·7H₂O and trimesic acid (H)₃BTC) is fully ground in an agate mortar, 0.01mol/L dilute NaOH solution is dissolved in the ground material and mixed for 20min by ultrasound to obtain mixed solution, and FeSO is contained in the mixed solution₄·7H₂The molar concentration of O is 0.053-0.107mol/L, the mixed solution is transferred to a microwave digestion instrument and reacts for 10-20min at the temperature of 180-; cooling the solutionAnd washing the mixture by using absolute ethyl alcohol and deionized water after cooling, and performing vacuum drying at 70 ℃ for 12h to obtain the heterogeneous solid catalyst Fe-MOF.

The mechanism of breaking collaterals is:

reaction I: ferrous iron on a Fe-MOF (iron-based metal organic framework) heterogeneous solid catalyst activates peroxydisulfate PDS to generate sulfate radicals and ferric iron, under the action of an electric field, the ferric iron on the Fe-MOF is reduced at a cathode, the valence state circulation of the Fe-MOF is realized, and the sustainable utilization of the catalyst and the utilization rate of an oxidant are improved:

Fe(II)+S₂O₈ ^2-→Fe(III)+SO₄ ^·-

Fe(III)+e^-→Fe(II)

and (2) reaction II: the strong oxidizing sulfate radical carries out gradual decarboxylation and complex breaking on Cu-EDTA to generate a weakly-complexed intermediate product or inorganic substance and free Cu ions:

SO^·-+Cu-EDTA→Cu-ED3A、Cu-ED2A、Cu-EDA、Cu-IMDA、CO₂+NO₃+H₂O+Cu²⁺

reaction III: chelated copper in the solution synergistically activates persulfate to generate sulfate radicals, and free copper ions after complex breaking are reduced on a cathode to form copper deposition so as to achieve the recovery effect:

Cu²⁺+S₂O₈ ^2-→Cu³⁺+SO₄ ^·-

Cu²⁺+2e^-→Cu(cathode)

the invention has the following beneficial effects:

1) the Fe-MOF (iron-based metal organic framework) material is used as a heterogeneous catalyst, the problems of large iron mud production amount, small pH application range, long reaction time, secondary treatment and the like in a homogeneous system in the existing Fenton technology are solved under the condition of ensuring effective breaking of the complex, no iron mud is produced, no subsequent treatment is needed, the catalyst can be continuously utilized, the pH application range is wide, and the method is a high-level oxidation catalysis complex-breaking treatment method for the heavy metal EDTA complex, which is efficient, stable and sustainable, wide in application range and free of secondary pollution.

2) In the system, under the electric auxiliary action, Fe (II) with catalytic activity on Fe-MOF can be continuously regenerated through a reduction reaction on a cathode, the valence state circulation of iron in the catalyst is accelerated, a good treatment effect can be achieved by applying a small amount of current and the catalyst, and the sustainable utilization of the catalyst and the utilization rate of an oxidant are improved.

3) The method for preparing the Fe-MOF heterogeneous solid catalyst by microwaves is simple, short in preparation period and high in crystallization rate. Compared with a hydrothermal method, the time required by the reaction is shortened to dozens of minutes from dozens of hours. Meanwhile, the preparation method takes water as a solvent, HF which is highly polluted and highly corrosive is not required to be added as a regulator, and the preparation method is green and clean. The prepared Fe-MOF has large specific surface area and a plurality of active sites, and can improve the catalytic efficiency.

4) Replacement of H in Fenton's system by Peroxydisulfate (PDS)₂O₂As an oxidant, the oxidation capacity is stronger, the pH application range is wider, high requirements on acid resistance and corrosion resistance of instruments and equipment are not required, the method for breaking the Cu-EDTA complex can realize complete degradation of the Cu-EDTA complex within 100min, and the degradation rate is higher than 90% within 60 min.

5) After the heavy metal-EDTA complex is oxidized and broken, free metal ions can be reduced and deposited at the cathode so as to recover copper, thereby achieving the effect of resource recovery.

6) The process is widely applicable to a variety of metal complexes.

Description of the drawings:

FIG. 1 shows the degradation efficiency of different systems for Cu-EDTA complexes;

the experimental conditions are as follows: the initial concentration of the Cu-EDTA complex wastewater is 1mmol/L, the pH is 3, and the current density is 0mA/cm²Or 2.86mA/cm²The dosage of Fe-MOF is 0g/L or 0.4g/L, the concentration of PDS is 0mM or 4mM, and the electrolyte Na₂SO₄The concentration is 0.02 mol/L.

FIG. 2 shows the degradation efficiency of the system to different heavy metal complexes, and the experimental conditions are as follows: the initial concentration of the heavy metal complex wastewater is 1mmol/L, and the current density is 2.86mA/cm²The dosage of Fe-MOF is 0.4g/L, the PDS concentration is 4mmol/L, the pH is 3, and the electrolyte N isa₂SO₄The concentration is 0.02 mol/L.

Fig. 3 shows the degradation efficiency of the system for different initial pH, experimental conditions: the initial concentration of the Cu-EDTA complex wastewater is 1mmol/L, and the current density is 2.86mA/cm²The dosage of Fe-MOF is 0.4g/L, the PDS concentration is 4mmol/L, the pH is 3-12, and the electrolyte Na₂SO₄The concentration is 0.02 mol/L.

FIG. 4 shows the degradation efficiency of the system for different catalyst addition amounts, the experimental conditions: the initial concentration of the Cu-EDTA complex wastewater is 1mmol/L, and the current density is 2.86mA/cm²The dosage of Fe-MOF is 0.2-1.2g/L, the concentration of PDS is 4mmol/L, the pH value is 3, and the electrolyte Na₂SO₄The concentration is 0.02 mol/L.

Fig. 5 shows the degradation efficiency of the system for different PDS concentrations, experimental conditions: the initial concentration of the Cu-EDTA complex wastewater is 1mmol/L, and the current density is 2.86mA/cm²The dosage of Fe-MOF is 0.4g/L, the concentration of PDS is 0.5-8mmol/L, the pH is 3, and the electrolyte Na₂SO₄The concentration is 0.02 mol/L.

Fig. 6 shows the degradation efficiency of the system for different current densities, the experimental conditions: the initial concentration of the Cu-EDTA complex wastewater is 1mmol/L, and the current density is 1.90-5.71mA/cm²The dosage of Fe-MOF is 0.4g/L, the PDS concentration is 4mmol/L, the pH is 3, and the electrolyte Na₂SO₄The concentration is 0.02 mol/L.

FIG. 7 shows the system for different electrolytes Na₂SO₄Degradation efficiency of concentration, experimental conditions: the initial concentration of the Cu-EDTA complex wastewater is 1mmol/L, and the current density is 1.90-5.71mA/cm²The dosage of Fe-MOF is 0.4g/L, the PDS concentration is 4mmol/L, the pH is 3, and the electrolyte Na₂SO₄The concentration is 0.005-0.08 mol/L.

The specific implementation mode is as follows:

the following is a further description of the invention and is not intended to be limiting.

Example 1:

and preparing Fe-MOF by a microwave method. Respectively weighing the components in a molar ratio of 1: 1 FeSO₄·7H₂O and trimesic acid (H)₃BTC) in an agate mortarMixing, dissolving in 10mL of 0.01mmol/L NaOH solution, ultrasonic mixing for 20min to obtain mixed solution, and FeSO in the mixed solution₄·7H₂And (3) transferring the mixed solution to a Polytetrafluoroethylene (PTFE) microwave container, reacting for 10min in a microwave digestion instrument at 200 ℃, cooling, washing for 3 times by using absolute ethyl alcohol and deionized water, and drying for 12h in a vacuum drying oven at 70 ℃ to obtain the Fe-MOF material, wherein the molar concentration of O is 0.8 mmol/L. The pore size and specific surface area of Fe-MOF are shown in Table 1.

TABLE 1

Adding heterogeneous solid catalyst Fe-MOF and Peroxydisulfate (PDS) into electrochemical reactor containing 100mLCu-EDTA complex waste water, Na₂SO₄As the electrolyte, electrolyte Na₂SO₄The concentration is 0.02mol/L, the initial concentration of Cu-EDTA in the wastewater is 1.0mmol/L, and the dosage of the heterogeneous solid catalyst Fe-MOF is 0.4 g/L; the dosage of the PDS oxidant is 4 mmol/L; adjusting initial pH to 3, arranging electrodes at two ends of the reaction container, connecting graphite plates as cathode and anode with DC power supply, magnetically stirring the wastewater solution at 800rpm for 100min, and current density of 2.86mA/cm²And after the reaction is finished, detecting by adopting a high performance liquid chromatography, wherein the complex breaking efficiency of the wastewater Cu-EDTA is 100%.

Example 2

Referring to example 1, other parameters were not changed except that the wastewater was wastewater containing Pb-EDTA complex, and the Pb-EDTA complex breaking efficiency of the wastewater was 100% after the reaction was completed (see FIG. 2).

Example 3

Referring to example 1, other parameters were not changed except that the wastewater was Ni-EDTA complex wastewater, and the Ni-EDTA complex breaking efficiency of the wastewater was 100% after the reaction was completed (see FIG. 2).

Example 4

Referring to example 1, other parameters were unchanged, except that the wastewater was Cd-EDTA complex wastewater, and after the reaction was completed, the complex breaking efficiency of the wastewater Cd-EDTA was 100% (see FIG. 2).

Example 5

Referring to example 1, other parameters were unchanged except that the initial pH was adjusted to 12 and the Cu-EDTA complexation breaking efficiency of the wastewater after the reaction was completed was 89.63% (see FIG. 3).

Example 6

Referring to example 1, other parameters were not changed except that the amount of Fe-MOF added as a catalyst was changed to 0.2g/L, and the Cu-EDTA complex breaking efficiency of the wastewater after the reaction was 98.27% (see FIG. 4).

Example 7

Referring to example 1, other parameters were not changed except that the amount of Fe-MOF added as a catalyst was changed to 1.2g/L, and the Cu-EDTA complex breaking efficiency of the wastewater reached 100% at 80min of reaction (see FIG. 4).

Example 8

Referring to example 1, other parameters were not changed except that the PDS concentration was changed to 0.5mmol/L, and the Cu-EDTA complex breaking efficiency of the wastewater after the reaction was 92.52% (see FIG. 5).

Example 9

Referring to example 1, other parameters were not changed except that the PDS concentration was changed to 8mmol/L and the Cu-EDTA complex breaking efficiency of the wastewater after the reaction was completed was 100% (see FIG. 5).

Example 10

With reference to example 1, the other parameters were not changed except that the current density was 1.90mA/cm²After the reaction is finished, the complex breaking efficiency of the wastewater Cu-EDTA is 100% (see figure 6).

Example 11

With reference to example 1, the other parameters were not changed except that the current density was 5.71mA/cm²After the reaction is finished, the complex breaking efficiency of the wastewater Cu-EDTA is 100% (see figure 6).

Example 12

Referring to example 1, other parameters were not changed except that the initial Cu-EDTA complex concentration was 0.4mmol/L and the Cu-EDTA complex breaking efficiency of the wastewater after the reaction was completed was 100%.

Example 13

With reference to example 1, the other parameters were unchanged, except that Na₂SO₄The electrolyte concentration is 0.005mol/L, and the complex breaking efficiency of the wastewater Cu-EDTA is 100 percent after the reaction is finished (see figure 7).

Example 14

With reference to example 1, the other parameters were unchanged, except that Na₂SO₄The electrolyte concentration is 0.08mol/L, and the complex breaking efficiency of the wastewater Cu-EDTA is 100% after the reaction is finished (see figure 7).

Example 15

With reference to example 1, the other parameters were not changed, except that FeSO was used for the Fe-MOF prepared₄·7H₂O and H₃The molar ratio of BTC is 1.5: 1, after the reaction is finished, the complex breaking efficiency of the wastewater Cu-EDTA is 100%.

Example 16

With reference to example 1, the other parameters were not changed, except that FeSO was used for the Fe-MOF prepared₄·7H₂O and H₃The molar ratio of BTC is 1.5: 2, after the reaction is finished, the complex breaking efficiency of the wastewater Cu-EDTA is 100%.

Example 17

Referring to example 1, other parameters were unchanged except that the microwave reaction temperature used for preparing Fe-MOF was 180 ℃, and the decomplexation efficiency of the wastewater Cu-EDTA was 100% after the reaction.

Example 18

Referring to example 1, other parameters are unchanged, except that the microwave reaction time for preparing the Fe-MOF is 20min, and the decomplexing efficiency of the wastewater Cu-EDTA is 100% after the reaction is finished.

As can be seen from examples 1 to 18, FeSO is present in the Fe-MOF catalyst₄·7H₂O and H₃The molar ratio of BTC is 1.5: (1-2) the preparation temperature is 180-²The addition amount of Fe-MOF is 0.2-1.2g/L, PDS, and the concentration is 0.5-8mmol/L, pH is in the range of 3-12, electrolyte Na₂SO₄The concentration is 0.02mol/L, the reaction time is 100min, the degradation rate of different heavy metal complex wastewater is still high, the adaptability is wide, the reaction condition is simple, and the practical engineering utilization value is high.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations and simplifications which do not depart from the scope of the present invention and are intended to be equivalent substitutions are included in the protection scope of the present invention.