CN101759253B - Electrochemical treatment method and electrochemical reactor - Google Patents

Abstract

The invention relates to an electrochemical treatment method and an electrochemical reactor. The electrochemical reactor comprises a cubic tank body. A plurality of polar plates are arranged in the tank body in parallel in the vertical direction. The polar plates are opposite negative and positive polar plates. A flow passage is arranged between the polar plates, and water to be treated flows through the flow passage. The bottom of the tank body is provided with a water inlet, and the top thereof is provided with a water outlet. A return pipeline from the water outlet to the water inlet is arranged outside the tank body. The return step is set in the water treatment, and the water to be treated returns multiple times, therefore the multiple electrochemical reaction treatment can be carried out; the returning water can carry the favorable gases of Cl2, O2 and the like generated in the treatment process into the flow passage, thereby saving the gas collecting equipment and being favorable for the electrochemical treatment process.

Description

Electrochemical process for treating and electrochemical reactor

Technical field

The invention belongs to the environment protection sewage process field, more specifically, relate to electrochemical process for treating, and wherein used electrochemical reactor.

Background technology

The electrochemical treatment method is a kind of water treatment method that development in recent years is got up, and its basic ideas are that relative positive/negative plate is set, and makes the space between pole plate become runner, make staying water flow through runner, in this process, electrode surface can produce some active intermediate products, as OH, OCL^-, H₂O₂, O₃Deng, these intermediate products participate in oxidize contaminants, and contaminant degradation is removed.

(1) produce hydroxyl radical free radical ( OH).The oxidizing potential 2.82 of hydroxyl is higher than other strong oxidizing property materials such as chlorine, ozone, hydrogen peroxide, " the active oxygen " of physical adsorption attitude ( OH) mainly play the electrochemical combustion effect, make the organism complete oxidation, this is an irreversible process.What take place when organic concentration is higher is direct electrooxidation, and when organic concentration is low, then take place be with The reaction of OH, as follows:

H₂O→^·OH+H⁺+e

Organism+ OH → product

2^·OH→H₂O+1/2 O₂

Class Fenton (Fenton) reaction can take place in electrochemical oxidation, produces OH oxidation organic pollutant, organic electrochemical oxidation is formed (electrochemistry oxygen with toluene turns to example) by following step:

O₂+2H⁺+2e→H₂ O₂

M^ox+e→M^red

M^red+H₂ O₂→M^ox+^·OH+OH^-

Toluene+OH → phenyl aldehyde, phenylcarbinol

OH+M^red→M^ox+OH^-

Oxygen molecule generates H in the cathode surface reduction₂O₂, H₂O₂With the as-reduced metal F enton reaction taking place generates OH, degradation of organic substances.

(2) produce hypochlorite (OCL^-).Organic matter removal is mainly realized by roundabout process during the chloride organic waste water of electrochemical treatment, and promptly the muriate electrochemical oxidation generates hypochlorite, and hypochlorite reoxidizes degradation of organic substances.In containing chlorine solution, OCL^-Realize by following reaction:

2CL^-→CL₂+2e

CL₂+H₂O→HO CL+HCL

HO CL→H⁺+OCL^-

The indirect oxidation of chlorine/hypochlorite that bright electrolysis produces plays a major role.This method has been effectively applied in the processing of dyeing waste water, formaldehyde waste water, percolate.

Have chlorion to have that following three reactions take place anode under the situation:

HO^-→^·OH+e

CL^-→^·CL+e

2CL^-→CL₂+2e

Following reaction takes place simultaneously:

CL₂+^·OH→HO CL+CL^-

CL₂+2H₂O→HO CL+H₃O⁺+CL^-

HO CL+H₂O→H₃O⁺+OCL^-

These have oxygenizement chlorine-bearing compound ( CL, CL₂, OCL^-Deng) and hydroxyl radical free radical ( OH) common oxidative degradation organic pollutant.

(3) produce ozone (O₃).Also have the investigator to think that anode can produce O₃Thereby, the oxidative degradation organism, electrochemical method can online generation O₃, it produces O than atmospherical discharges₃Make things convenient for manyly.O₃Produce by following reaction:

3H₂O→O₃(g)+6e+6H⁺

O₂+H₂O→O₃(aq)+2e+2H⁺

O₃Have very strong oxidation capacity, can pass through the online generation of electrochemical process O₃, be used for oxidative degradation, sterilization and disinfection of water pollutant etc.

(4) produce hydrogen peroxide (H₂O₂).Do not mentioned O in front₂Get electronics at negative electrode, reduction reaction takes place generate H₂O₂Its forming process may be the O that is adsorbed on the cathod catalyst surface₂By trapped electron, form peroxy ion O₂^-, form H by series reaction then₂O₂

O₂+e→O₂^-

O₂^-+H⁺→HO₂^·

O₂^-+HO₂^·→O₂+HO₂^-

2HO₂^·→H₂O₂+O₂

HO₂^-+H⁺→H₂ O₂

By aforementioned background art as can be known, electrochemical treatment is complicated chemical reaction process, and the factor that influences treatment effect is also inevitable a lot, and in actual applications, the flow rate of water flow and the residence time are exactly a pair of comparatively contradiction of puzzlement.

Its structure of electrochemical reactor all is that the polylith pole plate is arranged in parallel within the cell body, control current by water distributor, header, aforesaid various electrochemical reactions take place, to reach processing intent in flow through the from bottom to top zone of two pole plates of the current that order need to be handled in this process.

Such treatment process, its effect is also not fully up to expectations; In the reactor use, the problem of pole plate passivation appears easily simultaneously.The applicant causes the flow velocity that has its source in of this problem not enough, thereby causes pole plate that bigger concentration difference is arranged through discovering in a large number, makes the pole plate passivation in the course of time.Simultaneously, flow velocity is crossed and also will be made slowly and the current undercompounding in zone influence treatment effect, also easy settled sludge.And if strengthen pressure simply, artificially improve flow velocity, will make pending current residence time in reactor not enough again, do not reach treatment effect.

Summary of the invention

The objective of the invention is to solve above-mentioned, a kind of electrochemical process for treating of more optimizing is provided because of the low excessively problem of bringing of flow velocity.

Another object of the present invention provides a kind of electrochemical reactor of more reasonable structure.

For realizing first goal of the invention, the technical solution used in the present invention is such: electrochemical process for treating, comprise relative positive/negative plate, under the pole plate switch-on regime, staying water flows through the runner between positive/negative plate, it is characterized in that: in the water body of the runner of flowing through, have at least a part to be back to the runner starting point, flow through runner once more by reflux line.

Further, the water yield that flows through runner for the first time is 1 with the ratio of the water yield of backflow: 0.5-5.

For realizing second goal of the invention, the technical scheme that is adopted is such: electrochemical reactor, comprise the cell body of a cubic, and the in the vertical direction parallel rows is shown some pole plates in the cell body; The cell body bottom is provided with water-in, and the top is provided with water outlet; It is characterized in that: cell body has a reflux line from the water outlet to the water-in outward in addition.

The present invention is provided with the backflow link in water treatment procedure, equaling has increased the flow of runner under the constant situation of treatment capacity; In fact make the pending water body runner of repeatedly flowing through, that is carried out repeatedly handling.So both can improve flow velocity, prolong the residence time of water body in runner again.On the other hand, in electrochemical treatment process, itself can produce Cl₂, O₂Deng gas, these gases are favourable to electrochemical reaction; These gases need collection and treatment separately in the prior art, and these gases are brought in the runner with the water body that refluxes among the present invention, have saved gas collection equipment and have helped electrochemical treatment process.

Description of drawings

Fig. 1 is the structural representation of electrochemical reactor of the present invention.

Embodiment

Embodiment describes in further detail the present invention below in conjunction with accompanying drawing.

Embodiment 1

Referring to accompanying drawing, present embodiment comprises acubical cell body 1, and the in the vertical direction parallel rows is shown some pole plates 2 in thecell body 1, and described pole plate 2 is relative positive/negative plate, the runner that has staying water to flow through between the pole plate 2;Cell body 1 bottom is provided with water-in 3, and the top is provided with water outlet 4, cell body also have outward one from water outlet 4 to water-in 3reflux line 5,reflux line 5 is provided with a valve 6, reflux ratio can be controlled by valve 6.

Described reflux ratio is for flowing through the ratio of the water yield with the water yield of backflow of runner for the first time.

Embodiment 2

By the present invention certain factory's waste water from dyestuff is handled,, divided four processing same former water.Be prior art for the first time, do not adopt reflux; Second and third, use different reflux ratios four times.Handle under the condition of voltage 100V, electric current 5A for four times, the reaction times all is 10 minutes.

Water quality data after former water and the processing sees the following form.

	Former water	Reflux ratio (1: 0)	Reflux ratio (1: 0.5)	Reflux ratio (1: 1)	Reflux ratio (1: 2)
						COD(mg/l)	6200	3500	3200	2950	2900
Colourity	500	90	80	75	75
						Flocculation time (min		30	20	15	18

Conclusion: after increasing reflux, all have anappointment 20% the raising of COD clearance and colourity, flocculation time also has minimizing.

Embodiment 3

By the present invention certain factory's heavy metal wastewater thereby is handled 1, same former water divides four processing.Be prior art for the first time, do not adopt reflux; Second and third, the different reflux ratios of four usefulness reflux.Handle under the condition of voltage 100V, electric current 5A for four times, the reaction times all is 10 minutes.

Water quality data after former water and the processing sees the following form.

	Former water	Reflux ratio (1: 0)	Reflux ratio (1: 0.5)	Reflux ratio (1: 1)	Reflux ratio (1: 2)
						COD(mg/l)	200	50	35	32	35
Cu ion (mg/l)	120	0.28	0.15	0.1	0.1
						Sexavalent chrome (mg/l)	55	0.1	0.02	0.01	0.01
Nickel ion (mg/l)	35	0.1	0.05	0.02	0.05

Conclusion: after increasing reflux, COD clearance and removal of heavy metal ions rate have significantly raising.

Claims (3)

1. electrochemical process for treating comprises relative positive/negative plate, under the pole plate switch-on regime, staying water flows through the runner between positive/negative plate, it is characterized in that: in the water body of the runner of flowing through, have at least a part to be back to the runner starting point, flow through runner once more by reflux line.

2. electrochemical process for treating according to claim 1 is characterized in that: the water yield that flows through runner for the first time is 1 with the ratio of the water yield of backflow: 0.5-5.

3. electrochemical reactor comprises the cell body of a cubic, and the in the vertical direction parallel rows is shown some pole plates in the cell body; The cell body bottom is provided with water-in, and the top is provided with water outlet; It is characterized in that: cell body has a reflux line from the water outlet to the water-in outward in addition.

Images