CN102234153A

CN102234153A - Method for reducing generation amount of bromate in ozone water treatment process through catalysis of Ce-MCM-48

Info

Publication number: CN102234153A
Application number: CN2010101567567A
Authority: CN
Inventors: 强志民; 陆晓巍; 张涛
Original assignee: Research Center for Eco Environmental Sciences of CAS
Current assignee: Research Center for Eco Environmental Sciences of CAS
Priority date: 2010-04-27
Filing date: 2010-04-27
Publication date: 2011-11-09

Abstract

The invention relates to a method for reducing the generation amount of bromate in the ozone water treatment process through catalysis of Ce-MCM-48. In the method, the generation amount of the bromate is greatly reduced by introducing a Ce-MCM-48 mesoporous molecular sieve forming catalyst in the ozone oxidation water treatment process. Filtered water which is subjected to treatment (coagulation, precipitation, filtration and the like) in the traditional water treatment process enters an ozone contact column and subjected to ozone aeration for 2 to 5 minutes, and water containing ozone enters a Ce-MCM-48 catalytic oxidation tank; or the filtered water is subjected to ozone aeration and Ce-MCM-48 catalytic reaction simultaneously. The Ce-MCM-48 mesoporous molecular sieve catalyst is prepared by synthesizing through hydro-thermal reaction, washing and roasting. The method has high efficiency for reducing the generation amount of the bromate. The Ce-MCM-48 forming catalyst has an effect of promoting ozone to oxidize organic matters.

Description

Utilize Ce-MCM-48 catalysis to cut down the method for bromate growing amount in the ozone water treating processes

Technical field

The present invention relates to a kind of method that bromate generates gesture of in the ozone oxidation process, cutting down, be specifically related to the catalysis when ozone oxidation bromine ion-containing water of a kind of Ce-MCM-48 of use mesoporous molecular sieve preformed catalyst and cut down the method that bromate generates gesture.

Background technology

In recent years, because more and more higher to the requirement of drinking-water quality, face of land water factory uses ozone getting more and more as the measure of tap water oxidation depollution.If contain bromide anion in the surface water, then can under the ozone oxidation condition, produce deleterious brominated by product.Bromide anion in the water can be oxidized to hypobromous acid in the ozone oxidation process, hypobromous acid further is oxidized to bromate.Bromate is decided to be 2B level carcinogens by international cancer research institution, and each developed country's drinking water standard and China's Urban water supply water quality standard all are decided to be 10 μ g/L to the maximum permissible concentration of bromate.Studies show that bromide ion concentration surpasses 50 μ g/L in the surface water, will produce bromate during ozone oxidation; Bromide ion concentration surpasses 100 μ g/L, just has the risk that bromate exceeds standard during ozone oxidation.The surface water of China's Coastal Areas has the situation of the super seasonal 200 μ g/L of surpassing of bromide ion concentration usually, even also find bromide ion concentration in the inland city water source up to more than the 100 μ g/L, so there is the relatively more outstanding bromate problem that exceeds standard in these areas when using ozone oxidation.In a single day bromate produces, and just is difficult to get rid of under the water treatment condition.Therefore, the problem of bromate has become the restrictive factor that ozone is applied to drinking water deep processing most critical.

In recent ten years, the foreign study personnel have carried out more research to the method for control bromate growing amount in the ozone oxidation process.The method of research has: add acid and reduce the pH value, add hydrogen peroxide, add ammoniacal liquor and chlorination ammonia (Cl ₂And NH ₃Add in proportion).Wherein, ammonification and reduction pH value can reduce the bromate growing amount about 50%.Yet these methods all have problems in actual applications.

Reduce pH and allow BrO ₃ ^-The intermediate product HOBr/OBr of forming process ^-Balance move to left O ₃Can only oxidation OBr ^-, can not oxidation HOBr, therefore can suppress bromate and generate.But, can increase total organic bromine (TOBr) output like this.In addition, the mode of adjusting pH value is also uneconomical in water factory both inconvenience.

Adding hydrogen peroxide is to utilize intermediate product HOBr/OBr ^-Can be by H ₂O ₂Be reduced to Br ^-Thereby, suppress HOBr/OBr ^-Generate, reduce BrO ₃ ^-Produce.But O ₃/ H ₂O ₂Can produce more OH, the OH of increase also can make Br ^-Approach by Br is oxidized to BrO ₃ ^-In fact, only add excessive H ₂O ₂Could reduce BrO ₃ ^-Produce.Excessive H ₂O ₂Form more residue, consume chlorine residue, and then influence the lasting sterilisation effect in the pipe network, and can cause piping corrosion.

Ammonification is to utilize HOBr/OBr ^-With the reaction of ammonia bromine is changed into bromine ammonia, bromine ammonia is oxidized to NO lentamente by ozone ₃ ^-And BrO ₃ ^-, make BrO ₃ ^-Generation lag behind.Add Cl ₂-NH ₃Be to add ammoniacal liquor ozone oxidation again behind the former water prechlorination.Br in the water ^-At first be oxidized to HOBr, then HOBr and NH by HOCl ₃Reaction generates NH ₂Br.Add Cl ₂-NH ₃Can reduce by 40% bromate growing amount than ammonification.Because having consumed ozone, ammonia decomposes the hydroxyl radical free radical that produces, so ammonification and chlorination ammonia have also weakened the ability of ozone oxidation organic pollutant.Moreover, the use meeting of ammonia produces more nitrogenous disinfection byproduct (DBP) (HANs) when chlorine disinfectant.Current research shows that HANs is more much higher than the toxicity of carbon containing disinfection byproduct (DBP) (as halogen acetic acid), so the method for this control bromate is brought insoluble new problem again.Because China surface water water source ammonia-nitrogen content height often, ammonification can not be accepted by water undertaking in water more in addition.

Summary of the invention

The objective of the invention is to introduce chemical agent to reduce bromate growing amount efficient lower and cause piping corrosion, produce problems such as toxic substance, and provide in a kind of ozone oxidation water treatment procedure solid phase to cut down the method that bromate generates gesture in order to solve in the present tap water ozone oxidation reaction process.The present invention introduces Ce-MCM-48 mesoporous molecular sieve preformed catalyst in the ozone oxidation water treatment procedure, significantly cut down the growing amount of bromate under the situation of not adding any chemical agent in water.Method steps of the present invention is as follows: water after the filter after handling through traditional water treating processes (coagulation, precipitation, filtration etc.) is carried out ozone contact aeration and preliminary Ce-MCM-48 catalyzed oxidation simultaneously, carry out further Ce-MCM-48 catalyzed oxidation again.

Different with aforesaid method is, and filter back water enters the ozone contact tower carries out ozonation aerated 2～5min, and water ozoniferous carries out Ce-MCM-48 catalyzed oxidation pond again; Or water after filtering carries out simultaneously ozonation aerated and Ce-MCM-48 catalyzed reaction.

Among the present invention used moulding Ce-MCM-48 intermediate pore molecular sieve catalyst be by by hydro-thermal reaction synthetic Ce-MCM-48 powder and aluminum oxide or silicon oxide and sesbania powder binding agent, nitric acid, water according to mass ratio 1: 1: 0.1: mix afterwards granulation or extrusion, again at 500 ℃ roasting 5hs obtain at 0.1: 1.The hydro-thermal of Ce-MCM-48 powder is synthetic to be obtained by following method: be 1: 0.17～0.6: 0.016～0.064: 0.5: 60～80 ratio thorough mixing, vigorous stirring according to the mol ratio of tetraethoxy, palmityl trimethyl ammonium chloride, sodium laurate (or sodium laurylsulfonate), sodium hydroxide, cerous nitrate, water, then 100～110 ℃ of crystallizations 1～3 day, through washing back burning-off organic formwork agent.

Through studies show that of contriver, Ce-MCM-48 has the efficient that very high reduction bromate produces, under the situation of bromide ion concentration 100～200 μ g/L, Ce-MCM-48 throwing amount 0.5g/L can reduce the bromate of filter back water more than 80% and generate, reducing the bromate of mineral water more than 95% generates, obtain than adding the high reduction bromate efficient that manys of chemical agent, and the output of bromo disinfection byproduct (DBP) also reduces by 20～30% than simple ozone oxidation.Simultaneously, catalysis can also improve the oxidation removal effect of ozone to organic pollutant.Ce-MCM-48 significantly reduces reason that bromate the generates intermediate product BrO of bromate generative process that has been its catalytic reduction.

Because the Ce-MCM-48 preformed catalyst also has promoter action to the ozone oxidation organism,, Ce-MCM-48 catalysis is well suited in urban surface water factory advanced treatment and the production of mineral water ozonization, using so cutting down the method for bromate.

Description of drawings

Fig. 1 is the schema of the embodiment of the invention 1.

Fig. 2 is the schema of the embodiment of the invention 2.

Fig. 3 is the schema of the embodiment of the invention 3

The accompanying drawing literal

1. 2. ozone of intaking, 3. ozone air inlets, 4. water outlets, 5. ozone contact towers, 6. reaction tanks of giving vent to anger

Embodiment

Embodiment 1

Water enters ozone contact tower (or pond) and contacts with ozone also and carry out Ce-MCM-48 catalyzed oxidation 2～5min simultaneously after the filter after (coagulation, precipitation, filtration etc.) are handled through the traditional water treating processes, and ozone dosage is 0.2～4.0mgO ₃/ (mgTOC), this process is finished ozone and is added and the part catalyzed oxidation; Two, water outlet enters oxidation pond again by Ce-MCM-48 catalyzed oxidation 8～10min, finishes effective reduction control of oxidation operation and bromate growing amount.Idiographic flow is seen in the Figure of description shown in Figure 1.

Embodiment 2

Different with aforesaid way one is, and filter back water enters the ozone contact tower carries out ozonation aerated 2～5min, and wherein ozone dosage is 0.2～4.0mgO ₃/ (mg TOC); The ozone water that contains of coming out from the ozone contact tower enters in the oxidation pond of loading the Ce-MCM-48 finished catalyst again, and the control catalyzed oxidation time is 8～10min.Idiographic flow is seen in the Figure of description shown in Figure 2.

Embodiment 3

The contact reacts integral pool of different with aforesaid way one is after filtering water the enters inner Ce-MCM-48 of filling finished catalyst carries out ozonation aerated and catalyzed reaction simultaneously, and the reaction times is 10～15min, and wherein ozone dosage is 0.2～4.0mgO ₃/ (mg TOC).Idiographic flow is seen in the Figure of description shown in Figure 3.

Claims

1. the method for bromate growing amount in the tap water ozone Oxidation Treatment process is cut down in a catalysis, the specific descriptions of this method are as follows: dosing in ozone contact tank (or tower) and the reaction tank by the machine-shaping of hydro-thermal reaction synthetic Ce-MCM-48 mesoporous molecular sieve, or dose both one of in, finish oxidizing reaction, Ce-MCM-48 reduces bromate generation gesture by catalytic reduction intermediate product BrO first mate in this reaction process, surface water filter back water or mineral water through the bromate rate ratio after the catalyzed reaction with condition under separately the bromate output of ozone oxidation reaction reduce significantly, the ozone oxidation organism is not produced negatively influencing simultaneously.

2. according to claim 1, it is characterized in that using the Ce-MCM-48 mesoporous molecular sieve that obtains by hydrothermal synthesis reaction to cut down the core active ingredient that bromate generates gesture as catalysis in the ozone oxidation process.

3. according to claim 2, it is characterized in that bromate cuts down process for synthetic catalyst: be 1: 0.17～0.6: 0.016～0.064: 0.5: 60～80 ratio thorough mixing, vigorous stirring according to the mol ratio of tetraethoxy, palmityl trimethyl ammonium chloride, sodium laurate (or sodium laurylsulfonate), sodium hydroxide, cerous nitrate, water, 100～110 ℃ of crystallizations 1～3 day, obtain Ce-MCM-48 behind the burning-off organic formwork agent then.

4. according to claim 1, active ingredient Ce-MCM-48 and aluminum oxide or silicon oxide and sesbania powder binding agent, nitric acid, water were according to mass ratio 1: 1: 0.1: (diameter 2～4mm) or extrusion become column (diameter 2mm to mix the back granulation at 0.1: 1, high by 4～5mm), obtain the Ce-MCM-48 finished product of machine-shaping again at 500 ℃ of roasting 5h.

5. according to claim 1, it is characterized in that finished product Ce-MCM-48 catalytic additive in ozone contact tank (or tower) and reaction tank, or dose both one of in, the amount of filling of catalyzer is 10～15min calculating according to an empty bed residence time.

6. according to claim 1, the intermediate product BrO of bromate generative process that it is characterized in that Ce-MCM-48 active ingredient catalytic reduction significantly reduces thereby make bromate generate gesture.

7. according to claim 1, it is characterized in that into the water bromide ion concentration is lower than in 300 μ g/L and the catalyzed reaction 15min, the Ce-MCM-48 catalyzer significantly reduces the bromate growing amount.

8. according to claim 7, Ce-MCM-48 catalysis can reduce bromate growing amount and mineral water the bromate growing amount 95% or more of surface water filter back water more than 80% than independent ozone oxidation.

9. according to claim 1, it is characterized in that in water, not adding any chemical agent in the ozone oxidation process, thereby avoided the generation of harmful side product.

10. according to claim 1, the adding of finished product Ce-MCM-48 catalyzer does not influence the organic effect of ozone oxidation.