A source of wastewater
"Fine chemical" term first came from Japan, in the 1970s, Japan to the production of any specialized functions, research and development, manufacturing and application of technology-intensive, formulated technology can be around the performance of the product, the added value of a high, high yield, small batch, multi-species chemical products, called fine chemicals, the production of fine chemicals industry, called the fine chemical industry, referred to as fine chemical industry. The production of fine chemicals industry, known as the fine chemical industry, referred to as the fine chemical industry. Our chemical industry has been recognized by most people's definition is: all can enhance or give a (kind of) product to a specific function, or itself has a specific function of small quantities, high purity chemicals, known as fine chemicals. The full name of the fine chemical industry is "fine chemical engineering", belonging to the chemical engineering discipline.
There are many types of fine chemicals, including a wide range, such as pharmaceuticals, pesticides, dyes, pigments, various intermediates, coatings, flavors and fragrances, cosmetics, toiletries and sanitary products, synthetic detergents, surfactants, printing inks and so on. Fine chemical plant wastewater discharged mainly from the following categories:
1. Process wastewater
Process wastewater refers to the production process generated by the concentrated wastewater (such as distillation residue, crystallization mother liquor, filtration mother liquor, etc.), generally speaking, there are organic pollutants content is higher, and some of the salt concentration is higher, and some have toxicity. Not easily biodegradable, heavier pollution of water bodies.
2. Washing wastewater
Washing wastewater includes some products or intermediate products of the refining process of the washing water, intermittent reaction reaction of the reaction equipment washing water. This type of wastewater is characterized by a lower concentration of pollutants, but the water volume is larger, so the total amount of pollutants discharged is also larger.
3. Ground washing water
Ground washing water mainly contains solvents, raw materials, intermediates and finished products scattered on the ground. This part of the water quality and quantity of wastewater is often very much related to the level of management. When the management is poor. The amount of water and rinse water is larger. And water quality is also poor, the total amount of pollutants will be a considerable proportion of the entire wastewater system.
4. Cooling water
But the water is generally released from the condenser or reactor jacket cooling water. As long as the equipment is intact without leakage, cooling water quality is generally good, should try to cool and reuse, not directly discharged. Direct discharge on the one hand is a waste of resources, but also cause thermal pollution. Generally speaking, cooling water reuse, there is always a part to be discharged, this part of the cooling water mixed with other wastewater, will increase the volume of treated wastewater.
5 . Running, bubbling, dripping, leaking and pollution caused by accidents
Operational errors or equipment leaks can cause pollution by spillage of raw materials, intermediate products or products, so there should be contingency measures for accidents in the overall consideration of wastewater treatment.
6 . Secondary pollution of wastewater
Secondary pollution of wastewater generally comes from wastewater or waste gas treatment process may form a new source of wastewater pollution, such as pretreatment process from the sludge dewatering system separated from the wastewater, wastewater discharged from the waste gas treatment absorption tower.
7. domestic sewage in the plant
Two characteristics of fine chemical wastewater
1 raw materials to petrochemicals, coal processing by-products of synthesis or plant extraction, synthesis and so on. A wide range of products, process complexity;
2 process using a large number of toxic and hazardous chemical raw materials, such as halogen compounds, nitro compounds, benzene, phenol, naphthalene and derivatives, with strong irritating odor;
3 process side reactions, resulting in a complex component of the wastewater;
4 contains a large number of organic matter (CODcr often up to tens of thousands of mg / L), high color, high salt content, extreme pH, and the waste water is a very complex, but also a large amount of organic matter (CODcr often up to tens of thousands of mg / L), high color, high pH, and a lot of waste water. High salt content, extreme pH, difficult to biochemical degradation;
5 high ammonia nitrogen or nitrogen compounds; lack of nutrients phosphorus:
6 is currently one of the most difficult to deal with industrial wastewater, must be strengthened to cleaner production and emission reduction measures, in order to achieve effective pollution control;
Three principles of governance of the industrial wastewater of the fine chemical industry
Most of the fine chemical wastewater belongs to the range of highly difficult wastewater (B Most of the fine chemical wastewater belongs to the range of high-difficulty wastewater (B:C less than 0.3). Fine chemical industrial wastewater is difficult to deal with the main content of only two, one of which is soluble substances, and the other is insoluble substances, summarize the removal of these two categories of substances for the removal of the means of two basic principles: first, the use of earth's gravitational force for solid-liquid separation; and secondly, the use of micro-organisms in nature will be degraded to carbon dioxide and water and the residual sludge.
For soluble organic matter in the difficult to degrade the toxic and harmful solvent removal can be used: adsorption, infiltration, blowing hair, high-temperature oxidation, chemical coagulation, composite oxidation, membrane separation method, the key to the technology is the non-biodegradable material into a biochemical degradation of substances in the use of high-temperature composite oxidation and micro-capture technology, the separation of water and solvents, the removal of high salt in the water crystallization technology etc. to remove.
For specific wastewater treatment, the technical means have a variety of forms: physical, chemical, biological, electrochemical, composite method. Advanced oxidation is the key technology for the biochemical transformation of wastewater, including high-temperature catalytic oxidation, light radiation oxidation, gas oxidation, electrolysis and so on. We can according to the analysis of different water samples, for different contents, different treatment requirements, technical and economic indicators to develop different treatment processes.
Four fine chemical wastewater physical treatment technology application
Fine chemical wastewater contains many toxic and harmful degradation of the same thing, the ratio of low, direct biochemical treatment of such waste
1 coagulation
In many physical treatment process, coagulation has the advantages of simple process, low operating costs, especially in the removal of colored pollutants is preferred. Pollutants are preferred. Since there are only a few common coagulants with good effect on dye decolorization, and a large amount of chemical sludge has no outlet, the research direction in recent years is to develop multi-functional and high efficient coagulants with wide range of application, strong decolorization ability, and good effect on organic matter removal, and to study the way of sludge comprehensive utilization. It is generally believed that the decolorization effect is mainly produced by coagulation of colloidal substances and the adsorption of tiny flocs, which is very important for the removal of water-soluble dyes; at the same time, through the bridging, electrical neutralization, the flocs generated are also loaded with microsuspended matter. The goal of coagulant formulation design is to improve the role of the above two aspects, and according to the differences in printing and dyeing wastewater, designed as a general-purpose and a few kinds of dyes are particularly effective in the special type, to become a series of products.
1.1 FC series
FC series of coagulants for reactive dyes, disperse dyes, direct dyes and sulfur dyes wastewater decolorization rate of 85% to 95%, the usual dosage of 200-300 ppm, Fe also has a certain effect on the removal of COD and PVA. When the dosage is 300PPm, the COD removal rate obtained from the experiment is 38%, and the PVA removal rate is 67.4%.
1.2 XP series
XP series coagulant also has a wide applicability, the experiment shows that it is effective for printing and dyeing wastewater consisting of 13 types of dyes, and the average COD removal rate is 78.6%.
1.3 PFS and MS high-efficiency coagulation technology
PFS is a kind of inorganic polymer flocculant, and MZ is a kind of newly-developed coagulant, that is, the key additive of the new technology, whose special coagulation aid lies in changing the water-soluble environment of some dyes, breaking the hydrophilic group of some dyes and destroying the double-bond structure of some dyes, and playing the role of adsorption and oxidation on some fuels and soluble organic matter, as well as acting as a bridging agent, which is also effective in the removal of COD. It can adsorb and oxidize certain fuels and soluble organic matter, and at the same time play the role of bridging. When PFS and MZ are mixed, it forms a compound salt of pure inorganic high polymer with extreme high charge and extreme high molecular type combined by ligand bond.When PFS and MZ are used together, its coagulation effect and treatment effect are better than the commonly used inorganic coagulants in the market, and reducing the dosage of PFS, it can play the effect of low-consumption and high-efficiency treatment.The main advantages of the process technology of PFS and MZ are the short process, good treatment effect, low operation cost, low cost, low cost of operation, low cost of operation, low cost of operation, low cost of operation, low cost of operation, low cost of operation, low cost of operation, low cost of operation, The main advantages of PFS-MZ process technology are short process flow, good treatment effect, low operation cost, low capital investment, the main structures can be combined into one, simple operation and management. The technology is characterized by mixing, flocculation, sedimentation, reflux four steps to complete the whole process.
1.4 Application of NE coagulant in wastewater treatment
The new NE coagulant is a kind of inorganic coagulant, which is mainly composed of compounds containing iron, magnesium, aluminum and other elements. It is characterized by high efficiency, low price and fast sludge settling speed. The coagulant has good effect on the treatment of printing and dyeing wastewater and steelmaking dust removal wastewater, and the treatment effect of NE coagulant and high efficient coagulant TS (code) is compared as follows:
(1)COD removal The removal rate of NE coagulant is generally higher than TS, and the removal rate of CODcr is generally 75%-85% with NE, while it is generally 60% with TS, and some of them have better results even under the same amount of use. Even in the case of the same amount of use, the CODcr removal rate using NE is about 40% higher than TS.
(2)Decolorization rate The decolorization rate of using NE is higher than that of TS, and the decolorization rate of using NE is generally 95%~100%, while the decolorization rate of TS can be up to 95%~100% of a part of the wastewater treatment, but for another part of the wastewater is 50%~75%.
(3) The amount of coagulant and cost Relatively speaking, the impact of the amount of NE on the COD removal rate is less than TS, in the case of the same amount of use, the cost of pharmaceuticals is about twice as low.
(4)Settling rate The settling performance of NE is better than that of TS, and it is found in the experiment that most of the coagulants have been settled after 10min of coagulation using NE.
(5)Usability of NE Especially suitable for wastewater with high alkalinity, desizing, boiling and dyeing are the more polluted sections with high alkalinity, which can be treated with NE.
1.5 Comprehensive utilization of chemical sludge produced by coagulation
They will be made into building materials such as floor tiles and veneer tiles with other chemical raw materials in certain ratios. With the XP series coagulant chemical sludge produced by 25% of the ratio with other materials made of veneer tiles have good mechanical properties, its strength is better than ordinary white tiles, dissolution test results meet the requirements, can be used for general purposes, and the price is lower than the white tiles.
2 electro-coagulation method to treat wastewater in the fine chemical industry
The basic principle of electro-coagulation floating method is to treat the wastewater to be treated as an electrolyte solution, electrochemical reaction occurs under the action of DC power supply. Oxidation reaction occurs at the anode, so that organic matter decomposition and oxidation into harmless components; reduction reaction occurs at the cathode, so that the oxidized pigment is reduced to colorless. Conventional electro-coagulation method is based on experimental coagulation tank voltage and electrode current density of the relationship between the electro-coagulation tank, and then decided to electro-coagulation tank of the total voltage, usually the tank voltage is less than the safety voltage of 36 V. But to meet the wastewater treatment of the electrode current density to achieve a certain effect of treatment, the total current density is very large, generally in the range of 1000-3000 amperes, and thus the wastewater treatment unit of electrical energy consumption is larger.
With the rapid development of electronic technology, the silicon controlled pulse circuit is applied to the rectifier of electric coagulation, and optimize the design of electric coagulation tank. Through repeated experimental research and productive operation to prove that the use of higher tank voltage can greatly reduce the total current intensity and reduce the electrolysis time, thereby improving current efficiency, reduce power consumption and iron consumption. Pulse action can make the surface of the pole plate to reduce the precipitates and maintain high current efficiency. High-voltage pulse electro-coagulation method is based on this principle developed a new method of wastewater treatment, wastewater decolorization treatment effect is particularly obvious. Its characteristics are as follows:
(l) high-voltage pulse electro-coagulation floating method of treatment process on the color removal rate of up to 90% ~ 95%, the water is clear, applicable to a wide range.
(2)Compared with conventional electro-coagulation method, the electric consumption and iron consumption are greatly reduced, and the operation cost is lowered.
(3) the process is flexible, adaptable, no matter what kind of products, can achieve better results. The process is particularly suitable for small and medium-sized textile printing and dyeing processing enterprises and township enterprises, there is a broad prospect of popularization and application.
(4)The sludge is dewatered by centrifugal dewatering, and the water content of the dewatered sludge is about 70%, so it can be directly bagged and shipped out to make bricks without secondary pollution.
(5) The wastewater can be reused after this process, which has good environmental and economic benefits. The study of electrochemical properties of dyestuffs shows that all kinds of dyestuffs in the electrolytic treatment, the size of its CODcr removal rate in the order of: sulfide dyestuffs, reducing dyestuffs > acid dyestuffs, reactive dyestuffs > neutral dyestuffs, direct dyestuffs > cationic dyestuffs. Except for the cationic dyes, the decolorization rate of all types of dyes was above 90%, and the decolorization rate was consistent with the CODcr removal rate.
All in all, electrolysis method has the advantages of provincial investment, occupying less land, good treatment effect, high degree of mechanization. At present, the method has a stereotyped equipment, and has been put into practice.
3 Iron chip microelectrolysis treatment of fine chemical industry wastewater
Iron chip microelectrolysis mechanism Iron chip microelectrolysis as the main treatment process to deal with wastewater, technically and economically feasible, with a reliable process, low investment, low operating costs, operation and management of the advantages of simplicity. When the carbon-containing cast iron chips and inert coke particles immersed in a conductive electrolyte solution, the formation of countless tiny primary cells, in its role in the formation of an electric field in the space, in the lower potential of the iron anode, iron loss of electrons to generate Fe2 +, into the solution, so that the flow of electrons to the carbon cathode, in the vicinity of the anion, the solution of dissolved oxygen to absorb the electrons to generate OH -, in acidic solution, the cathode produces a new ecological [H]. In acidic solutions, the cathode produces a new ecological [H], which in turn generates hydrogen to escape. The electrode reaction
is as follows
Anode: Fe? - 2e → Fe2+ Eo (Fe2+ / Fe) = 0.44V
Cathode: 2H+ +2e →2[H] →H2, Eo (H+ / H) = 0.00V
O2 + 4H+ + 4e →2H2O Eo (O2) =1.23V
O2 + 2H2O + 4e →4 OH- Eo (O2 / OH-)=1.23V
From the above reaction equation, it can be seen that due to the continuous generation of Fe2+, it can effectively overcome the polarization effect of the anode, which promotes the electrochemical corrosion of iron, and a large amount of Fe2+ enters into the solution, forming a flocculant with high adsorption and flocculation activity, and effectively removing the dye in the dyeing wastewater. The flocculant with high adsorption flocculation activity can effectively remove the dye colloidal particles and impurities in the dyeing wastewater. In acidic solution, the new ecological [H] produced by the electrode reaction can oxidize and reduce with many components in the solution, which can destroy the chromophores of dye molecules in the dyeing wastewater and achieve the purpose of decolorization. Therefore, it can be considered that the mechanism of iron filings microelectrolysis treatment of dyeing wastewater is the result of oxidation-reduction adsorption-flocculation and other integrated effects. Normally, the pH of the influent water of the iron filtration column is 4~6, and the pH of the neutralization and precipitation is 7~8; the HRT of the dyeing wastewater in the iron filtration column is 30min, and the precipitation time in the precipitation tank is 60min, and the HRT of the sand filtration column is 30min.
It is technically and economically feasible to use the iron filtration microelectrolysis as the main treatment technology to treat the wastewater with a reliable process, low investment, easy to operate and manage, Low operating costs, easy operation and management.
4 Electrochemical method - self-coagulation and electrostatic coagulation treatment of fine chemical wastewater
4.1 Self-coagulation effect
Wastewater contaminants in the mixing of substances, due to the colloidal contamination particles on the surface of the reaction of the reduction of the free energy, will be in the wastewater treatment system from the dispersed state into the aggregated state, resulting in the self-coagulation effect. The effect of self-coagulation will be produced. Appropriate adjustment of the pH value of the wastewater will contribute to this effect, the use of a single variety of dyes printing and dyeing wastewater, in the case of intermittent addition of a small amount of coagulant, but also to promote the role of self-coagulation.
4.2 electrostatic coagulation
In the dispersed state of wastewater pollution particles, when entering a granular material gap between the same number of electrostatic field, due to the electrostatic field on the particles of the attraction of the particles and particles of the diffuse layer of the charge of the compression, resulting in a forced electric neutralization, and then due to the release of the surface energy of aggregation of sinking, and then by the particles of the material is composed of a bed of filtration of the retention.
Because the electrostatic treatment is the use of electrolytic Yang on the aggregation of particles, there is no loss of electrons, so the power consumption is very small, can be ignored.
5 Precipitation and flotation method of fine chemical wastewater treatment
At present, most of the domestic and foreign treatment of fine chemical wastewater physical and chemical method of precipitation, flotation or a combination of the above methods and the development of new technologies. The main methods are combined precipitation method, air flotation and combined precipitation method and CS series of double-drawing air flotation and precipitation method.
The speed of air flotation separation is determined by the size of the density of particles and liquids, air flotation treatment of industrial wastewater, has the advantages of saving investment, occupying a small area, fast separation speed, and good treatment effect
6 Adsorption method for the deep treatment of fine chemical wastewater
6.1 Adsorbent research and application
6.1.1 Activated carbon adsorbent
Practical evidence has shown that granular activated carbon adsorbent can be used for the treatment of fine chemical wastewater, but it is not suitable for the treatment of fine chemicals. It has been proved in practice that the adsorption and removal ability of granular activated carbon for various dyes is in the order of alkaline＞acid＞direct＞sulfurized dyes. Activated carbon has the most ideal decolorizing effect on dye molecules with molecular weight around 400, and it is also better for the adsorption of dyes with small molecular weight, while the decolorizing effect on hydrophobic dyes is poor.
6.1.2 Mineral adsorbents
(1) Imamura kaolin, marble powder, lava powder mixed according to 1:1:1, forging to get the decolorant can be better to Imamura in addition to the dye composition and chromaticity of wastewater.
(2) Okada: hydroaluminum quartzite (allopane) colloidal soil can be used for dyeing and printing wastewater.
(3) Activated white clay has good decolorizing effect on benzene azo disperse dyes.
(4) Plagioclase zeolite can effectively remove the dye components in wastewater after acid and alkali treatment and then activation, and the decolorization rate is 99.7%.
(5)The adsorption efficiency of mackinawite on dye is high, with good decolorization rate and CODcr removal rate, China's mackinawite is rich in resources, and the prospect of opening up this technology is broad.
(6) The use of Aconite powder as an adsorbent to remove the color of printing and dyeing wastewater.
(7) The use of magnesium-type adsorption of MgO, Al2O3, clay activity of a MgO?-clay treatment of printing and dyeing wastewater.
(8) Deep decolorization of printing and dyeing wastewater using activated diatomaceous earth (Al2O3 and Fe2O3 mainly).
(9) SiO2 adsorption for removal of basic dyes is an economical and efficient treatment process.
(10) Natural montmorillonite treatment of acidic cationic dye-containing wastewater, decolorization rate of up to 90% or more, CODcr removal rate of up to 96.9%
6.1.3 Coal and coal residue adsorbent
Experimentally proved that, with the best decoloration effect of 80% of the particle size, chromaticity >70%. Activated coal treatment of printing and dyeing wastewater has the advantages of low investment, occupies an area of less, easy to operate, easy to manage, stable treatment effect.
6.1.4 Natural waste adsorbents
Charcoal, rice husk, corn cobs, bagasse, peat, sawdust, etc. are natural adsorbents.
6.1.5 Ion exchange resin adsorbent
In recent years, for the water-soluble ionic dyes wastewater decolorization difficulties, the use of sulfonated coal and modified cellulose ion-exchange resin decolorization research. In addition, the use of special fibers and special processing made of polyphthalamide fibers, activated carbon fiber decolorization technology also has a lot of research.
6.2 Combination of adsorption method of the new process
6.2.1 Activated carbon filled electrode electrolysis method
This process has the following characteristics of good processing effect, no secondary pollution decolorization effect, do not add other decolorization oxidant, decolorization effect up to the above activated carbon does not need to regenerate the processing equipment is simple to manufacture a wide range of applications.
6.2.2 Corrosion electrode method
Corrosion electrode method of wastewater treatment has a variety of mechanisms, mainly electrochemical, with reduction and degradation, adsorption and coagulation. This method is characterized by waste treatment, resource conservation, low investment and low operating costs. The process is simple, covers a small area, easy to start, simple operation and management, especially for small and medium-sized textile printing and dyeing plant wastewater treatment.
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6.2.3 Adsorption and chemical coagulation method
The use of flue ash adsorption and chemical coagulation method to treat woolen textile dyeing and printing wastewater. Chemical coagulation half cinder adsorption method can also be used to treat cotton textile printing and dyeing wastewater.
Practice has proved that the development of cheap, efficient and new adsorption materials and the study of adsorption method of optimization of the combination of process flow is a new way of wastewater decolorization and deep treatment.
7 Membrane separation method for fine chemical wastewater
7.1 Dynamic membrane
After the study, it is considered that from the treatment effect and economic ZRO, PAA dynamic membrane is feasible, and the actual closed loop, indicating that the stability of the membrane, the flux and the interception rate is satisfactory after the washing of wastewater after reverse osmosis, and its permeate water and chemical reuse rate can reach 88% to 96%. The utilization rate of the permeate water and chemical substances after reverse osmosis can reach 88%～96%, and the rest also meets the wastewater discharge standards.
The effective reuse of the remaining waste liquid and reverse osmosis concentrate is also completely feasible, and the effective means to achieve this purpose is to determine the amount of auxiliaries and dyestuff replenishment through experiments, which will undoubtedly greatly improve the utilization rate of the waste dyeing liquid, and ultimately achieve the full cycle of the process of no wastewater discharge. The high operating pressure and high energy consumption are the shortcomings of dynamic reverse osmosis membrane.
7.2 Cellulose membranes
Vitamin membranes (CA) selectivity with the membrane surface and a variety of dyestuff isomers interact with a huge change, but due to the membrane material itself in the pH, temperature, and other aspects of the shortcomings of the membrane materials are gradually being phased out by the new membrane materials.
CTA reverse osmosis membrane solves the problem of dyeing wastewater used for water recirculation, CTA is better than CA in terms of pH resistance, pressure resistance, temperature resistance, etc., but the high-pressure operation required by reverse osmosis is still its shortcomings.
7.3 Polyalum ultrafiltration membrane
Polyalum ultrafiltration membrane has become one of the most competitive ultrafiltration membranes due to its good physical and chemical stability, pH range of 1 to 18, the maximum permissible temperature of 120 ° C, and has a good resistance to oxidation, chlorine and other properties.
7.4 Charged ultrafiltration and loose reverse osmosis membranes
7.4.1 Introduction
Charged ultrafiltration or loose reverse osmosis membranes are used to describe the separation performance between reverse osmosis and ultrafiltration of a membrane. Charged UF membranes are defined by the presence of charged groups in their chemical structure, whereas loosened RO membranes are named after their physical structure. They tend to refer to membranes that retain only 20-30% of monovalent salts, such as NaCl, and should have a high separation rate of 500-2000 molecular weights, while maintaining a high water flux. In addition, charge ultrafiltration maintains the characteristics of ultrafiltration at low pressure, and the membrane is outstanding in pH, pressure, contamination and temperature resistance. The molecular weight of general dyes is exactly in the interception range of this membrane, especially ionic dyes, due to the role of fixed ions on the membrane, its separation performance is difficult to compare with the neutral membrane.
7.4.2 Preparation
The use of chemical modification of polyalum, and then made into a base film, and further hydrophilic composite layer and base film for chemical reaction, and then in the hydrophilic solvent crosslinking made of composite membranes, so that the composite layer and the base film not only does not appear to peel off the phenomenon, but also show resistance to solvents, compression, acid and alkali resistance, the maximum temperature of 70 ℃
7.4.3 Conclusion
The charged ultrafiltration membrane will be the most competitive membrane material for dyeing wastewater treatment in the future due to its special MWCO range and high flow rate and low pressure operation. In addition, the membrane is pressure-resistant, acid and alkali resistant, pollution-resistant and so on, if coupled with computer-aided color matching and other means, will make the printing and dyeing wastewater to get the maximum recycling and reuse, but also in line with the emission standards.
8 chemical treatment methods
8.1 Chemical oxidation
(1) oxidation decolorization, the appropriate catalyst can improve the decolorization rate of O3 oxidation. The catalytic rate includes MnO2 catalyst with activated carbon as the skeleton and ZnSO4 as the catalyst.
(2) Decolorization by H2O2 oxidation.
(3) Fenton reagent decolorization technique.
(4) ClO2 oxidative decolorization.
8.2 Chemical reduction
The reducing agent is mainly iron filings.
9 Ion Pair Extraction Method
9.1 Extraction Mechanism
Under acidic conditions, long-chain amines react with dye molecules containing sulfonic acid groups to form hydrophobic ion pairs that accumulate in organic phases such as excess amine phases, thus separating them from the aqueous phase. Phase separation can be achieved with the aid of inert, non-polar solvents, preferably hydrocarbons. Suitable amines include aromatic amines such as primary amines such as naphthylamine, secondary amines, and tertiary amines.
Suitable amines include primary aromatic amines such as naphthylamine, secondary amines and tertiary amines.
9.2 Operation
The extraction method is operated by adjusting the wastewater to a suitable pH, then mixing it with amines and non-polar inert solvents, and then shaking it. Wastewater pH treatment to, a state when the decolorization is basically complete. Recovery of the organic phase If the organic phase contains reactive dyes, the inert solvent can be recovered by distillation, and if properly adjusted, the amine can also be reused, in this case, the distillation residue must be handled in accordance with the special waste regulations, while the organic phase can choose to dispose of by direct incineration.
The amine-solvent mixture containing aqueous NaOH is re-extracted.
Treating the amine, solvent and dye mixture with an aqueous solution is an ingenious solution in the presence of metal complex dyes, so that the dyes enter the aqueous phase and are reapplied to the dyeing plant as a solution, and the amine-solvent mixture is returned to the decolorization cycle.
Physical-chemical method as an important sewage treatment method is fine chemical industry environmental protection is playing an increasingly important role, many new methods are also emerging, they are for China's environmental protection and the development of fine chemical industry has played a great role in promoting.
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