CN104071874A - Electrode oxidation process used for removing cyanides and heavy metals - Google Patents

Abstract

The invention provides an electrode oxidation process used for removing cyanides and heavy metals. The process combination technology belongs to the fields of water treatment and environmental protection and is mainly used for removing cyanides and heavy metals, electrode oxidation technology is adopted, and activated carbon is used as a catalytic carrier to improve the oxidation efficiency. The main indexes of treated water meet the relevant requirements of national first grade wastewater emission standard GB8978-1996. The key point of the process lies in that the activated carbon is introduced to serve as the catalytic carrier to successfully solve the problems that complexes formed by the cyanides and heavy metals are hard to break, the broken heavy metal ions are more easier to form compound precipitates with hydroxy radicals, and the broken free cyanide radicals are oxidized by the electrode more easily, and the industry difficulty is solved.

Description

A kind of for removing the anodizing technique of prussiate and heavy metal

Technical field

This process combination technology belongs to water treatment environmental protection category, is mainly used in the removal of prussiate and heavy metal, adopts anodizing technology, and taking gac as catalytic carrier, to improve oxidation efficiency.After processing, water quality leading indicator reaches the related request of country-level wastewater discharge standard GB8978-1996.

Background technology

This Technology has adopted anodizing technology, utilizes anodizing to remove Cyanide in Waste Water compound and heavy metal, and anodizing can make cyanogen root CN-be degraded to carbonate CO32-and nitrogen N 2.The great amount of hydroxy group OH-that utilizes electrode hydrolysis to produce, can make heavy metal ion generate precipitation.Reaction formula is as follows:

CN ^-+OH ^-→CO ₃ ^2-+N ₂↑+H ₂O+e

Cu ^2-+OH ^-→Cu(OH) ₂↓

Zn ²⁺+OH ^-→Zn(OH) ₂↓

Ag ⁺+OH ^-→AgOH↓

The main standard data in national wastewater treatment first discharge standard GB8978-1996 are quoted.

The highest permission of pollutent emission concentration unit: mg/L

Sequence number	Pollutent	The highest permission emission concentration
			1	Total mercury	0.05
2	Mercury alkylide	Must not detect
			3	Total cadmium	0.1
4	Total chromium	1.5
			5	Sexavalent chrome	0.5
6	Total arsenic	0.5
			7	Total plumbous	1.0
8	Total nickel	1.0
			9	Benzo (a) pyrene	0.00003
10	Total beryllium	0.005
			11	Total silver	0.5
12	Totalαradioactivity	1Bq/L
			13	Total beta activity	10Bq/L
14	Total cyanogen compound	0.5
			15	Copper	0.5
16	Zinc	2.0

Summary of the invention

The principal feature of this novel process is, remove in cyanogen and heavy metal process in anodizing, introduce gac as catalytic carrier, because various heavy metal ion easily form complex compound with multiple cyanogen roots, as: network cyanogen closes copper [Cu (CN) 4] 2-, network cyanogen closes silver [Ag (CN) 3] 2-, if do not crack these complex compounds, is just unfavorable for that subsequent reactions generates the precipitation of hydroxide of heavy metal.Add gac as catalytic carrier, accelerated exactly cracking of these heavy metal complex, complexing cyanogen is transformed into after free Cyanide more easily oxidized, heavy metal ion after separating with complexing cyanogen root more easily with the precipitation of hydroxide of OH-generation heavy metal.

Introduced gac as catalytic carrier after, reaction efficiency greatly improves, and guarantees to have reacted rear water quality leading indicator and reaches standard-required.

Tool is stopped embodiment

Add catalytic carrier gac at anodizing trench bottom, the 20-30% of the useful volume that quantity is groove, adopts 24V direct supply, and current density is according to prussiate in water and heavy metal content capable of regulating.

Optimal processing parameter is: initial pH on wastewater value 10, polar plate spacing 20mm, current density 18.0mA/cm2, waste water circulation flow velocity 64mL/min.Electrolysis 50min, prussiate mass concentration is down to 0.20mg/L from 29.84mg/L, and clearance is 99.6%; Heavy metal copper ionic concn is down to 0.35mg/L from 54mg/L, and clearance is 99.7%.Heavy metal concentration of silver ions is down to 0.31mg/L from 52mg/L, and clearance is 99.8%.Total cyanogen and heavy metal in processed waste water can reach " GB8978-1996 integrated wastewater discharge standard " primary standard.

Claims (6)

1. remove in the waste water treatment process application containing prussiate and heavy metal in degraded, adopt anodizing technique, use gac as catalytic carrier, improve oxidation removal efficiency.Result: in water, prussiate, by anodizing, reaches the national cyanide wastewater emission standard of 0.5mg/L.Heavy metal ion is if Cu2+ is lower than the national heavy metal wastewater thereby emission standard of 0.5mg/L.

2. anodizing principle:

The step more complicated of anodizing reaction, the principal reaction formula it has been generally acknowledged that is as follows:

1)、CN ^-+OH ^-→CO ₃ ²+N ₂↑+H ₂O+e

2)、Cu ²+OH ^-→Cu(OH) ₂↓

3)、Zn ²+OH ^-→Zn(OH) ₂↓

3. be alkalescence because of such waste water, so, for reducing running cost, in alkaline environment direct oxidation, pH value>=10, in anodizing process, cyanogen root CN ^-be oxidized to carbonate and nitrogen, thereby reach degraded cyanogen root object.

4., in anodizing process, can be hydrolyzed simultaneously and produce great amount of hydroxy group OH ^-, hydroxyl and heavy metal ion combination, can produce heavy metal precipitation, as: cupric ion Cu ²⁺and OH ^-reaction, can generate copper hydroxide precipitate C u (OH) ₂thereby, reach removal heavy metal object.

5. electrode adopts platinum alloy series, taking gac as catalytic carrier, can greatly improve reaction efficiency, reduces running cost and energy consumption.

6. this technique is invented claimed scope:

Under alkaline condition, directly process containing cyanogen and heavy metal wastewater thereby by electrode oxidizing process, emphasis is to adopt gac as support of the catalyst, and after processing, prussiate and heavy metal reach national wastewater treatment first discharge standard.Heavy metal refers to: mercury, cadmium, chromium, arsenic, lead, silver, copper, zinc etc.

Quote the main standard data in national wastewater treatment first discharge standard GB8978-1996:

The highest permission of pollutent emission concentration unit: mg/L

Sequence number Pollutent The highest permission emission concentration 1 Total mercury 0.05 2 Mercury alkylide Must not detect 3 Total cadmium 0.1 4 Total chromium 1.5 5 Sexavalent chrome 0.5 6 Total arsenic 0.5 7 Total plumbous 1.0 8 Total nickel 1.0 9 Benzo (a) pyrene 0.00003 10 Total beryllium 0.005 11 Total silver 0.5 12 Totalαradioactivity 1Bq/L 13 Total beta activity 10Bq/L 14 Total cyanogen compound 0.5 15 Copper 0.5 16 Zinc 2.0