Bimetallic catalyst of organo-chlorine pollutant and its production and application in the degradation water
Technical field
The present invention relates to the quick catalysis reduction dechlorination of organo-chlorine pollutant in the water, belong to water treatment and water prevention and cure of pollution field, relate in particular to organo-chlorine pollutant bimetallic catalyst and its production and application in a kind of degradation water.
Background technology
Chloro organic cpd is important chemical material, intermediate and organic solvent, is widely used in industries such as chemical industry, medicine, agricultural chemicals, process hides.This compounds mainly comprises chlorinated aliphatic hydrocarbon, chlorination aromatic hydrocarbon and derivative thereof.In its use, chloro organic cpd enters environment by the approach such as burning of volatilization, container leakage, discharge of wastewater, the applications of pesticide and chlorinated organics finished product.In addition, what extensively adopt now is the method for drinking water disinfect with chlorine, also can produce the DBPs based on chlorinatedorganic.These pollutant chemistry stable in properties and have toxicity, in case enter natural water with the The Long-term Effect mankind and ecological environment, many chloro organic cpds have " three cause effect " (carcinogenic, teratogenesis, mutagenesis) or suspicious " three cause effect ", be the pollutants of the preferential control in various countries.In 129 kinds of environment priority pollutants that the U.S. announced in 1977, it is halides and derivative thereof that kind more than 60 is arranged, and on " blacklist " that the European Community announces, what rank the first is chlorohydrocarbon and the compound that can form chlorohydrocarbon in environment.Therefore the processing to chloro organic cpd is the important topic of studying in the environmental protection field always, and is extremely urgent to the improvement of this pollutant.
Because chlorinatedorganic toxicity is big, is difficult to biodegradation, therefore adopts traditional bioanalysis to handle organo-chlorine pollutant and be restricted.At present, the processing to chlorinatedorganic in the water mainly contains following several:
(1) physico-chemical process.The low carbon number chlorinatedorganic has high volatile volatile, and characteristics such as low boiling and low solubility can adopt physico-chemical process to be separated.Gas formulation and seed activity carbon adsorption have been used to remove organochlorine in chlorinatedorganic in the waste water, the especially drinking water.In the chlorinated organics wastewater treatment of reality, the gas formulation often is used in combination with absorption method, isolates chlorinated organics with recovery.Physico-chemical process technology is simple, treatment effect is better, but gas formulation and absorption method just chlorinatedorganic is separated from aqueous phase, fundamentally do not eliminate organo-chlorine pollutant, in processing procedure, also may cause new pollution, limit it in application in engineering.
(2) microbiological anaerobic facture.Chlorinatedorganic generally is difficult to aerobic degradation, can reach the purpose of reduction dechlorination with anaerobic process, but anaerobic process can not make the thorough mineralising of organo-chlorine pollutant, catabolite is bigger than parent product toxicity sometimes, and there is long processing period, shortcoming such as floor space is big.
(3) photocatalytic oxidation.Under UV-irradiation, adopt solid-state TiO
2Be catalyst, produce highly active electronics and hole, the hole combines with the chlorinatedorganic molecule and it is oxidized into carbon dioxide and chlorion.This technology is applicable to the chlorinatedorganic waste water of handling low concentration, has advantage such as be swift in response, oxidation is thorough, but because energy consumption is higher, the disposal cost costliness, and problem such as treating capacity is little has limited the practical application of this technical method.
(4) supercritical water oxidation method.Utilize the character of water under supercriticality, make gas and chlorinatedorganic soluble in water fully, form the homogeneous oxidizing system, eliminated the interphase mass transfer ability, improved reaction rate, degree of oxidation also improves thereupon, just can be in several seconds under 400~600 ℃ with the chlorinatedorganic structural deterioration, and reaction is relatively fully, thoroughly.But the deficiency that exists is that energy consumption is big, simultaneously catabolite Cl
-Have severe corrosive, make supercritical water oxidation method be restricted the processing of chlorinatedorganic.
(5) Zero-valent Iron reducing process.Since people such as Gillham in 1994 proposed electronics that the Zero-valent Iron corrosion produces and can make the chlorinatedorganic reduction dechlorination, Zero-valent Iron dechlorination technology was with low cost and treatment effect is good and receive much attention with it.But there are shortcomings such as degradation rate is slow, the easy generation in surface passivation layer in Zero-valent Iron in the dechlorination process, limited further developing of Zero-valent Iron technology.People such as Mallat find to plate the activity that the bimetallic system that forms behind the high metal of reduction potential can strengthen Zero-valent Iron on the Zero-valent Iron surface.Chinese patent CN1183316A is plated to the Zero-valent Iron surface with palladium, to improve chlorinatedorganic reduction dechlorination speed, still, no matter is to adopt iron powder plating palladium or iron powder to mix palladium, all exists problems such as noble metal additive decrementation and processing cost height.People such as Elliott find to adopt the nano zero valence iron with high-specific surface area can improve reduction dechlorination speed, the organic effect of degradating chloro significantly improves, but problem such as this method exists that complicated process of preparation, cost are higher, storage stability and the degraded dechlorination usefulness that continues are relatively poor.
Summary of the invention
The objective of the invention is for problem such as overcome above-mentioned technical matters complexity, cost height, energy consumption is big, treating capacity is little and proposed a kind ofly to degrade the fast iron nickel bimetal catalyst of dechlorination of organo-chlorine pollutant in the water, another object of the present invention provides the preparation method and the application thereof of above-mentioned bimetallic catalyst.
Technical scheme of the present invention is: utilize the reproducibility iron filings to make kernel, adopt liquid phase reduction to prepare and a kind of organo-chlorine pollutant in the water is had active height, good stability of quick degraded dechlorination effect, the iron nickel bimetal that processing cost is low, usefulness removes the organo-chlorine pollutant in the water.
Concrete technical scheme of the present invention is: a kind of to the degrade bimetallic catalyst of dechlorination of organo-chlorine pollutant in the water, it is characterized in that its component is iron nickel bimetal and carrier, the mass ratio of iron nickel bimetal and carrier is 100: (1-10), the mass ratio of iron nickel is 100 in the wherein said iron nickel bimetal: (1-5), described carrier is a modified zeolite.
The present invention also provides the preparation method of above-mentioned bimetallic catalyst, and its step comprises:
A. liquid phase reduction prepares the iron nickel bimetal
Earlier nickel salt is dissolved in the deionized water, is configured to nickel salt solution; To measure excessive 1.4~1.6 times sodium dithionite by chemical reaction and be dissolved in the sodium hydroxide solution, be made into alkaline reducing solution; Then iron filings are joined in the nickel salt solution and stir fast, then slowly add alkaline reduction liquid again, the control reaction temperature is reacted, and makes the liquid of iron content nickel bimetal.Filter this liquid, with deionized water filter cake is washed till neutrality, dehydrate processing again, promptly can be made into the iron nickel bimetal, wherein the mass ratio of the addition of iron filings and nickel is 100: (1-5);
B. the preparation of modified zeolite
With the zeolite washing by soaking, then with the zeolite roasting, again the zeolite after the roasting is ground to form particle, particulate zeolites is inserted in the cationic surfactant solution, put into the constant temperature oscillator vibration after shaking up, so that displace the inorganic cation in the zeolite; Take out the back and use the deionized water washing by soaking, dehydrate processing, can make modified zeolite;
C. iron nickel bimetal Preparation of catalysts
The modified zeolite that the iron nickel bimetal that steps A is prepared and step B prepare is with mass ratio 100: ratio (1-10) is evenly mixed, and is iron nickel bimetal catalyst.
Wherein nickel salt solution preferably sulfuric acid nickel or nickel chloride solution in the steps A, concentration is 0.2~0.5mol/L; Reaction temperature is 20~40 ℃ in the steps A, and the reaction time is 1~2h; Add iron filings granularity be preferably 1~3mm.
Wherein step B mesolite sintering temperature is 450~600 ℃, and the zeolite roasting time is 1.5~2.5h.The optional natural zeolite of zeolite, also optional commercially available zeolite, the preferred 0.4~0.8mm of the particle diameter of zeolite.Cationic surfactant solution is preferably quaternary ammonium salt cation surfactant among the step B, and mass concentration is 10~20%.Zeolite vibrates in constant temperature oscillator, and temperature is controlled at 15~30 ℃, and duration of oscillation is 1~2h.
The present invention also provides above-mentioned bimetallic catalyst to contain application in the chloro organic pollutant wastewater in processing, evenly be filled into this catalyst in the reactor, adopt the mode at upper reaches to pass through reactor waste water, according to the kind and the concentration of organo-chlorine pollutant in the water, water is 30~60min in the time of staying of catalyst in reactor layer; The degree of degraded dechlorination is analyzed wherein Cl by timing sampling
-Concentration and chlorinatedorganic concentration and know.Reaction condition with the dechlorination of degrading preferably is:
A.4~40 ℃ common temperature, general optimum temperature is 15~25 ℃, i.e. normal temperature
B. the pressure of reaction system is 0.8~1.2 atmospheric pressure
C. the pH value of reaction system is 3~9, and optimum value is 4-6.
Beneficial effect:
1. liquid phase reduction prepares the iron nickel bimetal, is reducing agent with the sodium dithionite, than reducing agent low prices such as sodium borohydride, diamines, and invalid decomposition minimizing, reducing activity is moderate, and safety and environmental protection.
2. liquid phase reduction prepares the iron nickel bimetal, passes through ion-exchange to prepare the iron nickel bimetal easy than original, and preparation time significantly shortens, and liquid phase reduction only needs 1~2h, and ion-exchange generally needs 24h.And pass through electron microscopic observation, nickel in the iron nickel bimetal of liquid phase reduction preparation exists with the form of whisker, and the nickel in the ion-exchange in the form of sheets, therefore the iron nickel bimetal of liquid phase reduction preparation all increases to some extent than the specific area and the porosity of ion-exchange, helps the raising of degradating chloro organic pollution speed.
3. adopting the zeolite of cationic surfactant modification is carrier, and modified zeolite has very strong adsorption capacity, and it can improve iron nickel degradating chloro treatment of organic matters of organic effect and speed with the organo-chlorine pollutant adsorption and enrichment in the water on the surface.And modified zeolite is a loose structure, catalyst that itself and iron nickel bimetal are formed, and structure is fluffy, and porosity is big, has reduced channel and wall flow phenomenon, has increased the contact area of chlorinatedorganic and iron nickel bimetal in the waste water, has improved degradation rate.Simultaneously, modified zeolite has reduced the area that the iron nickel bimetal is in contact with one another as the inertia component, and long-time running can effectively suppress filler and harden, and keeps the reactivity of catalyst, can continue degradating chloro organic pollution efficiently.
4. Zero-valent Iron degradating chloro organic pollution generally can only carry out under acid condition, and the pH value scope that the present invention is suitable for is big, can not only carry out under acid condition, and can carry out under neutral and weak basic condition, alkali is transferred in acid adjustment before and after having avoided reaction, and water outlet pH value can be directly up to standard.
5. floor space of the present invention is little, and capital equipment is-reactor; Technical process is simple, only needs to add the logical then waste water of a certain proportion of bimetallic catalyst and get final product in reactor; Disposal cost is low, and the operating cost major part is reflected in the consumption of iron, and the used iron filings of the present invention are the waste material of metal works processing, low price have " treatment of wastes with processes of wastes against one another " meaning, and nickel can not consume substantially as negative electrode in degradation process, modified zeolite cheap can use for a long time.
Description of drawings
Fig. 1 is the sem photograph on iron filings surface
Fig. 2 is the sem photograph on the iron nickel bimetal surface of ion-exchange preparation
Fig. 3 is the sem photograph on the iron nickel bimetal surface of liquid phase reduction preparation
The iron filings surface is a smooth structure as seen from Figure 1, and the iron filings surface has generated a spot of sheet nickel among Fig. 2, and the iron filings surface has generated a large amount of nickel whiskers among Fig. 3.By measuring, the iron nickel bimetal of liquid phase reduction preparation is than nickel content height in the iron filings bimetallic of ion-exchange preparation, and specific area is big, has improved reduction dechlorination speed.
The specific embodiment
Embodiment 1
Handling the effect that contains tetrachloro-ethylene (PCE) waste water with method of the present invention and prior art compares
(1) contains the water quality of PCE waste water
The concentration 142mg/L of PCE
PH value 5.74
Cl
-Concentration<2mg/L
(2) take by weighing the iron filings of three parts of equals in quality, first part does not add catalyst nickel and modified zeolite, is simple iron filings, is called filler A; Second part is adopted ion-exchange to prepare the iron nickel bimetal, and the concentration of nickel sulfate solution is 0.4mol/L, and the wherein contained nickel and the mass ratio of iron filings are 3: 100, and preparation time is 2h, and the iron nickel bimetal that makes does not add modified zeolite and forms filler B; The 3rd part is adopted liquid phase reduction to prepare the iron nickel bimetal, the concentration of nickel sulfate solution is 0.4mol/L, sodium dithionite is dissolved in the sodium hydroxide solution of 0.2mol/L and is configured to contain the alkaline solution that sodium dithionite is 0.6mol/L, the iron filings that with granularity are 1~3mm then join stirring fast in the nickel sulfate solution, the wherein contained nickel and the mass ratio of iron filings are 3: 100, react 2h down at 30 ℃, leave standstill filtration then, be washed till neutrality with deionized water, make the iron nickel bimetal after dehydrating; With natural zeolite deionized water washing by soaking 3 times, then at 500 ℃ of following roasting 2h, again the zeolite after the roasting is ground to form particle, granularity is 0.4~0.8mm, it is 15% softex kw solution that particulate zeolites is placed mass concentration, puts into constant temperature oscillator at 20 ℃ of reaction 1.5h down, spends deionised water after the taking-up 3 times, after dehydrating, can make modified zeolite; Iron nickel bimetal and modified zeolite are mixed by mass ratio at 100: 5, form filler C.A, B, three parts of fillers of C are respectively charged in the reactor that internal diameter is 100mm, and the height of filler is 600mm.Following implementation step is identical.
(3) at normal temperatures, the waste water that will contain PCE is with the mode at the upper reaches packing layer by reactor, and the control time of staying of water in packing layer is 45min.
(4) water outlet sample analysis Cl wherein
-The concentration of concentration and PCE.
In the reactor that above-mentioned A, B, three kinds of fillers of C are formed, adopt same process to handle the waste water that contains tetrachloro-ethylene (PCE), the result after the processing shows, treatment effect the best of C, the effluent quality testing result sees Table 1.
Table 1 the inventive method and prior art treatment effect are relatively
Embodiment 2 usefulness method of the present invention is handled the waste water that contains trichloro-ethylene (TCE)
(1) contains the water quality of TCE waste water
The concentration 37mg/L of TCE
PH value 6.35
Cl
-Concentration<2mg/L
(2) adopt liquid phase reduction to prepare the iron nickel bimetal, the concentration of nickel chloride solution is 0.5mol/L, sodium dithionite is dissolved in the sodium hydroxide solution of 0.3mol/L and is configured to contain the alkaline solution that sodium dithionite is 0.75mol/L, the iron filings that with granularity are 1~3mm then join stirring fast in the nickel chloride solution, the wherein contained nickel and the mass ratio of iron filings are 5: 100, react 1.5h down at 40 ℃, leave standstill filtration then, be washed till neutrality with deionized water, make the iron nickel bimetal after dehydrating; With natural zeolite deionized water washing by soaking 3 times, then at 500 ℃ of following roasting 2h, again the zeolite after the roasting is ground to form particle, granularity is 0.4~0.8mm, it is 10% DTAC solution that particulate zeolites is placed mass concentration, puts into constant temperature oscillator at 15 ℃ of reaction 1h down, spends deionised water after the taking-up 3 times, after dehydrating, can make modified zeolite; Iron nickel bimetal and modified zeolite are mixed into uniform bimetallic catalyst in 100: 10 ratio of mass ratio.It is in the 150mm reactor that the bimetallic catalyst for preparing is packed into internal diameter, and the height of packing layer is 800mm.
(3) at normal temperatures, the waste water that will contain TCE is with the mode at the upper reaches packing layer by reactor, and the control time of staying of water in packing layer is 60min.
(4) water outlet sample analysis Cl wherein
-The concentration of concentration and TCE, and pH value.The effluent quality testing result is:
The concentration 1.1mg/L of TCE (clearance is 97.1%)
PH value 6.82
Cl
-Concentration 28.4mg/L (dechlorination rate is 94.8%)
Embodiment 3 usefulness method of the present invention is handled the waste water that contains tetrachloromethane (CT)
(1) contains the water quality of CT waste water
The concentration 217mg/L of CT
PH value 6.51
Cl
-Concentration<2mg/L
(2) adopt liquid phase reduction to prepare the iron nickel bimetal, the concentration of nickel chloride solution is 0.2mol/L, sodium dithionite is dissolved in the sodium hydroxide solution of 0.1mol/L and is configured to contain the alkaline solution that sodium dithionite is 0.3mol/L, the iron filings that with granularity are 1~3mm then join stirring fast in the nickel chloride solution, the wherein contained nickel and the mass ratio of iron filings are 1: 100, react 1h down at 20 ℃, leave standstill filtration then, be washed till neutrality with deionized water, make the iron nickel bimetal after dehydrating; With natural zeolite deionized water washing by soaking 3 times, then at 500 ℃ of following roasting 2h, again the zeolite after the roasting is ground to form particle, granularity is 0.4~0.8mm, it is 20% OTAC solution that particulate zeolites is placed mass concentration, puts into constant temperature oscillator at 30 ℃ of reaction 2h down, spends deionised water after the taking-up 3 times, after dehydrating, can make modified zeolite; Iron nickel bimetal and modified zeolite are mixed into uniform bimetallic catalyst in 100: 1 ratio of mass ratio.It is in the 200mm reactor that the bimetallic catalyst for preparing is packed into internal diameter, and the height of filler is 600mm.
(3) at normal temperatures, the waste water that will contain CT is with the mode at the upper reaches packing layer by reactor, and the control time of staying of water in packing layer is 30min.
(4) water outlet sample analysis Cl wherein
-The concentration of concentration and CT, and pH value.The effluent quality testing result is:
The concentration water outlet of CT has not detected CT
PH value 7.14
Cl
-Concentration 195.8mg/L (dechlorination rate is 97.9%)
The Zero-valent Iron that the iron nickel bimetal that embodiment 1 shows liquid phase reduction preparation is better than using always to the degradation effect of tetrachloro-ethylene and the iron nickel bimetal of ion-exchange preparation.The data of embodiment 1~3 show that the iron nickel bimetal of liquid phase reduction preparation has good degradation effect to typical organo-chlorine pollutant in the water, can be used as the improvement method that contains the chloro organic wastewater.