Method for Mechanochemical Reduction and Degradation of Perfluoro and / or Polyfluoroalkyl Sulfonic Acid Substances

Abstract

The present invention relates to a method for the mechanochemical reduction and degradation of perfluoro- and / or polyfluoroalkyl sulfonic acid substances, belonging to the technical field of treatment of highly toxic organic solid waste. The present invention discloses a mechanochemical method using zinc powder, iron powder and metal compounds (oxides, hydroxides or oxyhydroxides) as a ternary grinding agent, realizing the complete degradation and defluorination of perfluoro / polyfluoroalkyl sulfonic acid solid hazardous waste. Compared with the single-component and binary grinding agent systems, this method has a higher defluorination efficiency. After 3 h of mechanochemical reaction, the defluorination rate of potassium perfluorooctane sulfonate can reach 100%. Compared with the existing mechanochemical treatment methods, the grinding agent of this method is inexpensive, non-toxic and easily available, the mechanochemical reaction conditions are milder, the treatment time is short, the energy consumption is low and the efficiency is high.

Description

Technical Field

[0001] The present invention belongs to the technical field of the treatment of highly toxic organic solid waste, and more specifically, relates to a method for the mechanochemical reduction and degradation of perfluoro and / or polyfluoroalkyl sulfonic acid substances, and particularly relates to a degradation method using alumina and zinc and iron metals as a mixed grinding agent to catalytically convert perfluoro / polyfluoroalkyl acid substances into non-toxic substances by mechanochemical action. Background Art

[0002] Perfluoro / polyfluoroalkyl sulfonic acids are a type of widely used surfactants. However, due to their strong chemical stability and high ecological toxicity, they are listed as a class of new pollutants under key control in China. Perfluorooctane sulfonic acid (PFOS) was listed as a persistent organic pollutant (POPs) in 2009. Since then, a variety of perfluoro / polyfluoroalkyl sulfonic acid substances (PFASs) with a perfluorocarbon number of 4 to 6 have been mass-produced and used as its substitutes. These substances have the characteristics of hydrophobicity and oleophobicity and are often used as oil repellents, dust repellents, pesticides, surfactants, anti-fog agents, etc. in the production fields of industrial and civil products. The chemical structure of PFASs is stable and difficult to be disposed of by biological and chemical methods. Therefore, the elimination technology of PFASs has received wide attention.

[0003] At present, most of the PFASs elimination technologies focus on the degradation and removal of PFASs in water, and insufficient attention has been paid to the removal technologies for PFASs in solid waste. However, the half-life of PFASs in solid media is longer, and they may migrate to water bodies, causing secondary water pollution. High-temperature incineration under aerobic conditions is a common method for treating solid waste, but the incineration of perfluorinated compounds easily produces greenhouse gases CF4 and C2F4 or corrosive gas HF. Therefore, it is urgent to develop new methods to replace the incineration treatment method. Mechanochemistry is considered a very promising method for treating POPs solid waste. During the ball milling process, mechanical force effects such as friction, collision, and extrusion between the grinding balls, grinding agents, and pollutants will activate the grinding agents to degrade organic pollutants. Zhang et al. used KOH as the grinding agent and degraded PFOS by ball milling mechanochemistry, almost achieving complete defluorination; however, KOH is prone to deliquescence and has strong corrosiveness. Cagnetta et al. degraded PFOS and perfluorooctanoic acid (PFOA) by La2O3 mechanochemistry and could convert organic fluorine into LaOF. Hu et al. and our research group et al. used Fe3O4 and iron powder, Al2O3 and aluminum powder as grinding agents to degrade PFOS or PFOA by mechanochemistry, respectively. The above-mentioned combination of metal oxides and zero-valent metals for the mechanochemical degradation of PFOA or PFOS demonstrated a synergistic effect. Since the reducing ability of aluminum powder is stronger than that of iron powder, the binary grinding agent system of aluminum powder and Al2O3 can efficiently degrade PFOA under milder ball milling conditions. However, when this system degrades PFASs, due to the stronger reducing ability of aluminum powder, the sulfonate group is reduced to toxic and harmful gas H2S, resulting in secondary pollution. In addition, since PFOS has one more CF2 unit than PFOA and the sulfonate group is more stable than the carboxylate group, the degradation of PFOS is relatively slow, and complete defluorination requires a longer reaction time or higher rotation speed. For example, the complete degradation of PFOS and PFOA by La2O3 mechanochemistry takes 10 h and 4 h, respectively; the degradation of PFOA by Al2O3 and aluminum powder is at 350 rpm, while the degradation of PFOS by Fe3O4 and iron powder is at 600 rpm. Summary of the Invention

[0004] The present invention solves the problems in the prior art such as strong corrosiveness of abrasives, high energy consumption in ball milling, or secondary pollution caused by toxic gas generation. The present invention provides a method for degrading perfluoro- and / or polyfluoroalkyl sulfonic acid substances (PFASs solid waste) by mechanical chemical reduction using a ternary abrasive agent of zinc powder, iron powder, and metal compound under normal temperature and pressure. The metal compound adsorbs perfluoro- and / or polyfluoroalkyl sulfonic acid substances, and zinc powder and iron powder provide electrons to reduce the C–F bond, and degrade perfluoro- and / or polyfluoroalkyl sulfonic acid substances under the action of mechanical force effect. In the present invention, the adsorbed water or coordinatively unsaturated Lewis acid sites on the surface of the metal compound can adsorb perfluoro / polyfluoroalkyl sulfonic acid target pollutants through hydrogen bond / electrostatic interaction, remove the terminal sulfonate group of the pollutants under the combined action of mechanical force effect and abrasive agent, and at the same time the abrasive agent is activated to generate electrons to attack perfluoro / polyfluoroalkyl sulfonic acid, realizing its reduction degradation.

[0005] According to the first aspect of the present invention, there is provided a method for degrading perfluoro- and / or polyfluoroalkyl sulfonic acid solid waste by mechanical chemical reduction using a ternary abrasive agent. Zinc powder, iron powder, metal compound, and alkyl sulfonic acid substance are added to a ball mill for ball milling. The metal compound is a metal oxide, metal hydroxide, or metal hydroxy oxide, and the alkyl sulfonic acid substance is a perfluoro- and / or polyfluoroalkyl sulfonic acid substance. The metal compound adsorbs perfluoro- and / or polyfluoroalkyl sulfonic acid substances, and zinc powder and iron powder provide electrons to reduce the C–F bond, and degrade perfluoro- and / or polyfluoroalkyl sulfonic acid substances under the action of mechanical force effect.

[0006] Preferably, the metal oxide is alumina, zinc oxide, lanthanum oxide, or manganese dioxide.

[0007] Preferably, the metal hydroxide is aluminum hydroxide, iron hydroxide, barium hydroxide, or calcium hydroxide; the metal hydroxy oxide is hydroxyaluminum oxide, hydroxyiron oxide, or hydroxycobalt oxide.

[0008] Preferably, the alkyl sulfonic acid substance is octane sulfonic acid, hexane sulfonic acid, butane sulfonic acid, sulfonic acid ether, octane sulfonate, hexane sulfonate, butane sulfonate, or sulfonic acid ether salt.

[0009] Preferably, the mass fraction of the alkyl sulfonic acid substance in the total reaction materials is 1% to 30%.

[0010] Preferably, the ratio of the total mass of zero-valent metal to the amount of substance of the metal compound is 0.1 to 5.

[0011] Preferably, the molar ratio of zinc powder to iron powder is 0.1 to 10.

[0012] Preferably, during the ball milling process, the mass ratio of grinding balls to materials is 10:1 to 100:1.

[0013] Preferably, the rotation speed of the ball milling is 100 to 500 rpm.

[0014] Generally speaking, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:

[0015] (1) The present invention uses a ternary abrasive of zinc powder, iron powder and metal compound (oxide, hydroxide or oxyhydroxide) to reductively degrade perfluoro / polyfluoroalkyl sulfonic acid. The adsorbed water or coordinatively unsaturated Lewis acid sites on the surface of the metal compound (oxide, hydroxide or oxyhydroxide) can adsorb the perfluoro / polyfluoroalkyl sulfonic acid target pollutant through hydrogen bonding / electrostatic / coordination interactions. Under the combined action of the mechanical force effect and the abrasive, the terminal sulfonate group of the pollutant is removed, and at the same time, the abrasive is activated to generate electrons to attack the perfluoro / polyfluoroalkyl sulfonic acid, realizing its reductive degradation. Compared with a single metal oxide (hydroxide or oxyhydroxide), zero-valent metal has a stronger reducing ability and can provide a large number of electrons to attack the perfluoro / polyfluoroalkyl sulfonic acid; zinc powder has a stronger ability to reduce and defluorinate than iron powder, but it will cause the sulfonate group to be reduced to the toxic gas H2S. The added iron powder can fix S 2- , avoiding the generation of harmful gases. In addition, compared with the sole use of zero-valent metal, the interaction between the metal oxide (hydroxide or oxyhydroxide) and perfluoro / polyfluoroalkyl sulfonic acid is stronger, which can adsorb it in the form of single molecules on the reaction interface, avoiding the formation of aggregates or clusters between multiple molecules, thus facilitating the attack of perfluoro / polyfluoroalkyl sulfonic acid by the adjacent zero-valent metal.

[0016] (2) There is a synergistic effect among the ternary abrasives of zinc powder, iron powder and metal oxide (hydroxide or oxyhydroxide) involved in the present invention, which can achieve rapid defluorination and degradation of perfluoro / polyfluoroalkyl sulfonic acid. The defluorination rate and defluorination efficiency are superior to those of the single-component and binary abrasive systems, and the treatment efficiency is also higher than that of the reported abrasive systems.

[0017] (3) The abrasives used in the present invention are all commercially available products with low cost, non-toxicity and easy availability. The treated products are inorganic carbon and inorganic fluorine, and no harmful substances are generated; the whole reaction is carried out at normal temperature and pressure, the mechanochemical reaction conditions are mild, the treatment time is short, the energy consumption is low, and the efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the defluorination rate of the ternary abrasive of zinc powder, iron powder and α-Al2O3 used in the present invention and the single-component and binary mechanochemical methods for treating PFOS in the comparative example.

[0019] Figure 2 This is the defluorination rate of the ternary abrasive of zinc powder, iron powder and α-Al2O3 (AlOOH or La2O3) used in the present invention for the mechanochemical degradation of PFOS.

[0020] Figure 3This invention changes the relative dosages of alumina and zero-valent metal, and the relative dosages of zinc powder and iron powder, and the apparent defluorination rate of PFOS by mechanical-chemical treatment with a ternary abrasive of zinc powder, iron powder and α-Al2O3.

[0021] Figure 4 This invention shows the XPS spectra of the products obtained by mechanical-chemical treatment of PFOS with a ternary abrasive of zinc powder, iron powder and α-Al2O3 for different reaction times.

[0022] Figure 5 This invention shows the effect diagram of mechanical-chemical treatment of potassium 1-chloro-perfluoroalkyl ether sulfonate (F-53B) with a ternary abrasive of zinc powder, iron powder and α-Al2O3.

[0023] Figure 6 This shows the effect diagram of the mechanical-chemical degradation of PFOS by this invention, KOH and La2O3 in the comparative example. Detailed implementation mode

[0024] In order to make the objectives, technical solutions and advantages of this invention clearer, the following further elaborates on this invention in combination with the attached drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this invention and are not used to limit this invention. In addition, the technical features involved in the various implementation modes of this invention described below can be combined with each other as long as they do not conflict with each other.

[0025] A method for mechanically-chemically reducing and degrading perfluoro- and / or polyfluoroalkyl sulfonic acid solid waste with a ternary abrasive of this invention, adding zinc powder, iron powder, metal compound and alkyl sulfonic acid into a ball mill tank for ball milling, where the metal compound is a metal oxide or metal hydroxy-oxide, and the alkyl sulfonic acid is a perfluoro- and / or polyfluoroalkyl sulfonic acid; the metal compound adsorbs the perfluoro- and / or polyfluoroalkyl sulfonic acid, zinc powder and iron powder provide electrons to reduce short-chain C–F bonds, and degrade the perfluoro- and / or polyfluoroalkyl sulfonic acid under the action of mechanical force effect to achieve deep defluorination.

[0026] In some embodiments, the metal oxide is alumina, zinc oxide, lanthanum oxide or manganese dioxide.

[0027] In some embodiments, the metal hydroxide is aluminum hydroxide, iron hydroxide, barium hydroxide or calcium hydroxide; the metal hydroxy-oxide is hydroxyalumina, hydroxyiron oxide or hydroxycobalt oxide.

[0028] In some embodiments, the alkyl sulfonic acid substances are octane sulfonic acid, hexane sulfonic acid, butane sulfonic acid, sulfonic ether, octane sulfonate, hexane sulfonate, butane sulfonate or sulfonic ether salt.

[0029] In some embodiments, the alumina includes α-alumina and γ-alumina.

[0030] In some embodiments, the mass fraction of the alkyl sulfonic acid substance in the total reaction materials is 1% - 30%, the molar ratio of the total mass of the zero-valent metal to the metal compound is 0.1 - 5, and the molar ratio of zinc powder to iron powder is 0.1 - 10.

[0031] In some embodiments, the mass ratio of the grinding balls to the materials is 10:1 - 100:1, and the rotation speed is 100 - 500 rpm.

[0032] A method for degrading perfluoro / polyfluoroalkyl acid substances by mechanochemical reduction according to the present invention specifically includes the following steps:

[0033] Step 1: At normal temperature and pressure, add PFASs solid waste, zinc powder, iron powder, and a metal compound (such as Al2O3) in a certain proportion into a 250 mL stainless steel ball mill tank, and then add stainless steel grinding balls with a diameter of 6 - 15 mm. Among them, PFASs account for 1% - 20% of the total material mass, and the mass ratio of the grinding balls to the materials is 50:1 - 100:1.

[0034] Step 2: Symmetrically fix the ball mill tank filled with materials and grinding balls on the ball mill, set the rotation speed of the ball mill to 250 - 350 rpm, the ball milling time to 5 - 240 min, stop for 2 min every 20 min of operation, and the ball mill operates in an alternating forward and reverse direction mode. When all PFASs in the materials are completely reacted and consumed, stop the mechanochemical reaction.

[0035] In some embodiments, the Al2O3 of the present invention includes different crystal forms (α-type, γ-type), or is one of Al(OH)3, AlOOH, ZnO, La2O3, MnO2.

[0036] In some embodiments, the mass fraction of the PFASs in the total reaction materials of the present invention is 1% - 20%, and the mass ratio of the grinding balls to the materials is 50:1 - 100:1.

[0037] The following are specific embodiments:

[0038] Example 1: Degradation of PFOS by a ternary grinding agent of zinc powder, iron powder, and α-Al2O3 by mechanochemical method

[0039] Mix 0.21 g of potassium perfluorooctane sulfonate solid powder, 0.74 g of zinc powder, 0.32 g of iron powder with 1.94 g of α-Al2O3, and then transfer them to a dry stainless steel ball milling jar. Then add 10 stainless steel grinding balls with a diameter of 15 mm and 20 stainless steel grinding balls with a diameter of 6 mm into the jar. The total weight of the grinding balls is 160 g. The volume of the ball milling jar is 250 mL, the internal depth of the jar body is 70 mm, and the inner diameter of the jar mouth is 77 mm. Connect the ball milling jar and the ball milling cover with a sealing ring. Fix the ball milling jar on the ball mill, set the rotation speed of the ball milling jar to 350 rpm, and carry out the ball milling reaction under normal temperature and pressure. Change the direction of the ball milling revolution every 20 min. After the ball milling mechanochemical reaction proceeds for 20, 40, 60, 80, 120, 180, and 240 min respectively, take out the ball milling jar and collect the solid powder in the jar body.

[0040] Accurately weigh 10 mg of the solid powder after the reaction for a certain time, dissolve it by heating with 1 mL of 40% sodium hydroxide solution, disperse it ultrasonically, centrifuge to take the supernatant, transfer the supernatant to a volumetric flask, add 10 mL of TISAB, dilute it to 50 mL with distilled water and detect the fluoride ion concentration using a fluoride ion selective electrode, and calculate the defluorination rate of PFOS and the apparent defluorination rate of the pseudo-zero order reaction.

[0041] Example 2: Degradation of PFOS by mechanochemical method using a ternary grinding agent of zinc powder, iron powder and AlOOH

[0042] Mix 0.21 g of potassium perfluorooctane sulfonate solid powder, 0.74 g of zinc powder, 0.32 g of iron powder with 1.94 g of AlOOH, and then start the mechanochemical degradation reaction according to the method of Example 1. After the ball milling mechanochemical reaction proceeds for 20, 40, 60, 80, 120, 180, and 240 min respectively, take out the ball milling jar, collect the solid powder in the jar body, and measure the defluorination rate of PFOS according to the analysis method in Example 1.

[0043] Example 3: Degradation of PFOS by mechanochemical method using a ternary grinding agent of zinc powder, iron powder and La2O3

[0044] Mix 0.21 g of potassium perfluorooctane sulfonate solid powder, 0.74 g of zinc powder, 0.32 g of iron powder with 1.94 g of La2O3, and then start the mechanochemical degradation reaction according to the method of Example 1. After the ball milling mechanochemical reaction proceeds for 20 and 40 min respectively, take out the ball milling jar, collect the solid powder in the jar body, and measure the defluorination rate of PFOS according to the analysis method in Example 1.

[0045] Example 4: Influence of the relative dosage of zero-valent metal and α-Al2O3 on the degradation of PFOS by mechanochemical method

[0046] Mix 0.21 g of potassium perfluorooctane sulfonate solid powder with a ball-milling aid, control the molar ratio of zinc powder to iron powder to be 2:1, change the relative ratio of α-Al₂O₃ to the metal, and then initiate the mechanochemical degradation reaction according to the above steps 1 and 2. After the ball-milling mechanochemical reaction proceeds for 20 and 40 min respectively, take out the ball-milling tank, collect the solid powder in the tank, and measure the defluorination rate of PFOS and the apparent defluorination rate of the pseudo-zero-order reaction according to the analysis method in Example 1.

[0047] Example 5: Influence of the relative dosage of zinc powder and iron powder on the mechanochemical degradation of PFOS by a ternary grinding agent

[0048] Mix 0.21 g of potassium perfluorooctane sulfonate solid powder with a ball-milling aid, keep the total mass of 1.93 g of α-Al₂O₃, zinc powder, and iron powder to be 1.06 g, change the relative ratio of zinc powder to iron powder, and then initiate the mechanochemical degradation reaction according to the method in Example 1. After the ball-milling mechanochemical reaction proceeds for 20 and 40 min respectively, take out the ball-milling tank, collect the solid powder in the tank, and measure the defluorination rate of PFOS and the apparent defluorination rate of the pseudo-zero-order reaction according to the analysis method in Example 1.

[0049] Example 6: Influence of the mechanochemical degradation of F-53B by a ternary grinding agent of zinc powder, iron powder, and α-Al₂O₃

[0050] Mix 0.21 g of 1-chloroperfluoroalkyl ether sulfonate potassium solid powder with a ball-milling aid, keep the total mass of 1.93 g of α-Al₂O₃, zinc powder, and iron powder to be 1.06 g, and initiate the mechanochemical degradation reaction according to the method in Example 1. After the ball-milling mechanochemical reaction proceeds for 20, 40, 60, and 80 min respectively, take out the ball-milling tank, collect the solid powder in the tank, and measure the defluorination rate of PFOS according to the analysis method in Example 1.

[0051] Example 7: XPS characterization of the products of the mechanochemical degradation of PFOS by a ternary grinding agent of zinc powder, iron powder, and α-Al₂O₃

[0052] Repeat the method of Example 1 according to the same steps described. In step 2, weigh 50 mg of samples of the ball-milling reaction for 0, 60, and 240 min for X-ray photoelectron spectroscopy characterization tests.

[0053] Comparative Example 1: Mechanochemical degradation of PFOS by a single grinding agent

[0054] 0.21 g of potassium perfluorooctane sulfonate solid powder was respectively mixed with 3 g of α-Al2O3, 3 g of zinc powder, and 3 g of iron powder, and then the mechanochemical degradation reaction was initiated according to the above-mentioned steps 1 and 2. After the ball-milling mechanochemical reaction proceeded for 20, 40, 60, 80, 120, and 240 min respectively, the ball-milling tank was taken out, the solid powder in the tank was collected, and the defluorination rate of PFOS was measured according to the analysis method in Example 1.

[0055] Comparative Example 2: Degradation of PFOS by binary grinding agent mechanochemical method

[0056] 0.21 g of potassium perfluorooctane sulfonate solid powder was respectively mixed with 1.93 g of α-Al2O3 and 1.06 g of iron powder, 1.93 g of α-Al2O3 and 1.06 g of zinc powder, 2.1 g of iron powder and 0.90 g of zinc powder, and then the mechanochemical degradation reaction was initiated according to the above-mentioned steps 1 and 2. After the ball-milling mechanochemical reaction proceeded for 20, 40, 60, 80, 120, and 240 min respectively, the ball-milling tank was taken out, the solid powder in the tank was collected, and the defluorination rate of PFOS was measured according to the analysis method in Example 1.

[0057] Comparative Example 3: Degradation of PFOS by KOH or La2O3 mechanochemical method

[0058] 0.21 g of potassium perfluorooctane sulfonate solid powder was respectively mixed with 3 g of solid KOH, 1.93 g of Fe3O4 and 1.06 g of iron powder, and then the mechanochemical degradation reaction was initiated according to the above-mentioned steps 1 and 2. After the ball-milling mechanochemical reaction proceeded for 20, 40, 60, 80, 120, and 240 min respectively, the ball-milling tank was taken out, the solid powder in the tank was collected, and the defluorination rate of PFOS was measured according to the analysis method in Example 1.

[0059] Results and analysis

[0060] The effect of the ternary grinding agent of zinc powder, iron powder and α-Al2O3 on the degradation of PFOS by mechanochemical method was tested according to Example 1. The results are as Figure 1 shown in a of. When the ball-milling mechanochemical reaction reached 60 min, the defluorination rate of PFOS in this ternary grinding agent system was 85.94%; when the reaction continued to 180 min, PFOS was completely defluorinated. However, as Figure 1 shown in b of, in Comparative Example 1, when zinc powder, iron powder or α-Al2O3 was used alone as the grinding agent, the defluorination rate of PFOS was slow, and the defluorination rates after 60 min of reaction were only 9.07%, 11.80% and 46.76% (as Figure 1 shown in b of); in Comparative Example 2 (as Figure 1As shown in a), when using α-Al2O3 and zinc powder, α-Al2O3 and iron powder, and zinc powder and iron powder as grinding agents respectively, the defluorination rate of PFOS after 60 min is improved, reaching 70.15%, 82.64% and 17.40% respectively. In comparison, the defluorination rate of the ternary grinding agent of zinc powder, iron powder and α-Al2O3 is significantly higher than that of other binary systems and single-component systems in the early stage of mechanochemical reaction. Within the first 40 min of the reaction, the relationship between the defluorination rate of PFOS and time conforms to pseudo-zero-order reaction kinetics, that is, the ratio of the defluorination rate of PFOS to time can be used as the apparent rate constant of this reaction. In comparison, the apparent defluorination rate of the mechanochemical degradation of PFOS by the ternary grinding agent of zinc powder, iron powder and α-Al2O3 is 2.04 min –1 , which are 13.28, 9.92 and 2.63 times that of using α-Al2O3, zinc powder and iron powder alone respectively, and about 1.4 times that of the binary systems of α-Al2O3 and zinc powder and α-Al2O3 and iron powder.

[0061] According to the methods of Example 2 and Example 3, ternary systems of AlOOH or La2O3 with zinc powder and iron powder respectively were used for the mechanochemical degradation of PFOS. As Figure 2 shown, when the mechanochemical reaction lasted for 4 h, the defluorination rate of the ternary grinding agent system of zinc powder, iron powder and La2O3 for existing PFOS was 82.4%; the defluorination rate of the ternary grinding agent system of zinc powder, iron powder and AlOOH for PFOS was 57.9%.

[0062] According to Example 4 and Example 5, the effects of the relative amounts of zero-valent metals and α-Al2O3 and the relative amounts of zinc powder and iron powder on the defluorination rate of PFOS were tested. First, the molar ratio of zinc powder to iron powder (n Zn / n Fe ) was fixed at 2, and the ratio of the mass of α-Al2O3 to the total mass of the ball-milling assistant (including α-Al2O3 and zero-valent metals) (m Al2O3 / m T ) was changed. The results are as shown in a) of Figure 3 . When using only zero-valent metals (Zn / Fe) as the control (m Al2O3 / m T = 0), the defluorination rate of PFOS was only 0.34 min –1 ; then, the content of α-Al2O3 was gradually increased, and the defluorination rate of PFOS increased sharply. When m Al2O3 / m T = 0.64, the defluorination rate of PFOS reached the maximum of 2.04 min –1 ; when the proportion of α-Al2O3 was continued to increase, the defluorination rate of PFOS decreased. When using α-Al2O3 alone, the defluorination rate of PFOS was 0.86 min –1 . Then, m Al2O3 / mT = 0.64, change n Zn / n Fe . The results are as Figure 3 shown in b below. When the molar ratio of zinc powder to iron powder (n Zn / n Fe ) increases from 0 to 2, the defluorination rate of the reaction for 40 min increases from 1.50 min –1 to 2.04 min –1 ; Continuing to increase n Zn / n Fe , the defluorination rate of PFOS gradually decreases.

[0063] The collected samples were analyzed by X-ray photoelectron spectroscopy (XPS) according to Example 7. The results are as Figure 4 shown. Figure 4 a in it is the high-resolution spectrum of C1s. Before the ball-milling mechanochemical reaction, the components with binding energies at 284.8 and 292.5 eV are attributed to exogenous contaminant carbon and the C–F bond in PFOS, respectively; when the mechanochemical treatment reaches 3 h, the peak of organic C–F disappears, and inorganic carbon is generated at 284.8 eV. Figure 4 b in it is the high-resolution XPS spectrum of F1s. Before the mechanochemical reaction, the component with a binding energy at 689.05 eV in the sample is the C–F bond in PFOS; as the reaction proceeds, the peak intensity of the organic C–F bond gradually decreases, and inorganic fluoride ions are generated at 685.16 eV, and the peak gradually increases; after the reaction for 3 h, the F1s peak corresponding to the C–F bond completely disappears, indicating that complete defluorination of PFOS is achieved.

[0064] The effect of the ternary grinding agent of zinc powder, iron powder and α-Al2O3 on the degradation of F-53B by mechanochemistry was tested according to Example 6. The results are as Figure 5 shown. When the ball-milling reaction reaches 80 min, the defluorination rate of F-53B can reach 82.5%, indicating that this ternary grinding agent system is also applicable to the degradation and defluorination of perfluoro / polyfluoroalkyl sulfonic acid ethers.

[0065] The ternary grinding agent system of zinc powder, iron powder and α-Al2O3 and the reported methods for degrading PFOS using KOH and the binary system of Fe3O4 and iron powder were tested according to Comparative Example 3. As Figure 6 shown, under the same experimental conditions, after ball-milling for 3 h, the defluorination rate of the ternary grinding agent system of zinc powder, iron powder and α-Al2O3 for PFOS is 100%, which is significantly higher than that of the systems using KOH (32.2%) and Fe3O4 / Fe (72.0%) as grinding agents. The above shows that compared with the systems reported in the literature, the ball-milling mechanochemical reaction conditions for treating PFOS with the ternary grinding agent system developed in the present invention are milder and the energy consumption is lower.

[0066] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for mechanically and chemically reducing and degrading perfluoro- and / or polyfluoroalkyl sulfonic acid solid waste by using a ternary abrasive, characterized in that, Zinc powder, iron powder, metal compounds and alkyl sulfonic acid substances are added to a ball milling tank for ball milling. The metal compounds are metal oxides, metal hydroxides or metal hydroxyoxides, and the alkyl sulfonic acid substances are perfluoro and / or polyfluoroalkyl sulfonic acid substances; the metal compounds adsorb perfluoro and / or polyfluoroalkyl sulfonic acid substances, and zinc powder and iron powder provide electrons to reduce the C–F bond and degrade perfluoro and / or polyfluoroalkyl sulfonic acid substances under the action of mechanical force effect; The metal oxide is alumina, zinc oxide or lanthanum oxide; The metal hydroxide is aluminum hydroxide, iron hydroxide, barium hydroxide or calcium hydroxide; the metal hydroxyoxide is hydroxyaluminum oxide, hydroxyiron oxide or hydroxycobalt oxide; The alkyl sulfonic acid substances are octane sulfonic acid, hexane sulfonic acid, butane sulfonic acid, sulfonic acid ether, octane sulfonate, hexane sulfonate, butane sulfonate or sulfonic acid ether salt.

2. The method for mechanically and chemically reducing and degrading perfluoro- and / or polyfluoroalkyl sulfonic acid solid waste by using a ternary abrasive as claimed in claim 1, wherein The mass fraction of the alkyl sulfonic acid substance in the total reaction materials is 1% to 30%.

3. The method for mechanically and chemically reducing and degrading perfluoro- and / or polyfluoroalkyl sulfonic acid solid waste by using a ternary abrasive as claimed in claim 1, wherein The ratio of the total mass of zinc powder and iron powder to the amount of substance of the metal compound is 0.1 to 5.

4. The method for mechanically and chemically reducing and degrading perfluoro- and / or polyfluoroalkyl sulfonic acid solid waste by using a ternary abrasive as claimed in claim 1 or 3, wherein The ratio of the amount of substance of zinc powder to that of iron powder is 0.1 to 10.

5. The method for mechanically and chemically reducing and degrading perfluoro- and / or polyfluoroalkyl sulfonic acid solid waste by using a ternary abrasive agent according to claim 1, characterized in that During the ball milling process, the mass ratio of the grinding balls to the materials is 10:1 to 100:

1.

6. The method for mechanically and chemically reducing and degrading perfluoro- and / or polyfluoroalkyl sulfonic acid solid waste by using a ternary abrasive agent according to claim 1, wherein The rotation speed of the ball milling is 100 to 500 rpm.

Images