Solvent extraction coal chemical high concentration phenol wastewater treatment
Coal chemical found in high concentration phenol wastewater of coal gas, coal quality, and the system of coal, coal carbonization to coal tar, coal tar hydrogenation and shale carbonization process.
The wastewater composition is complicated, containing tar, carbon dioxide, hydrogen sulfide, phenol, ammonia, dust, fatty acids and other impurities, including phenol concentration often as high as several thousand to tens of thousands of mg/L, cannot be directly handled by biochemical method.
Common processing method is in phenol ammonia pretreatment before the biochemical unit, among them, the phenolics often by solvent extraction.
solvent extraction method is the most critical part is the selection of extraction agent, the stand or fall of extraction solvent properties directly affect the extraction process of energy and material consumptions.
Study of removing phenol extraction agent at home and abroad has a lot of, typical types of the extractant hydrocarbons, alcohols C, ethers, esters, ketones and complexation extraction agent.
At present, more and more mature in industrial application of removing phenol extraction agent is mibk (
And diisopropyl ether.
Diisopropyl ether low boiling point solvent recovery of low energy consumption, the unit of phenol extraction effect is better,
For phenol distribution coefficient is 36.
5, but its polyphenol extraction effect is very poor,
For hydroquinone distribution coefficient is 1.
03, does not apply to high content of polyphenol in wastewater.
MIBK to unit of phenol and polyphenol has higher distribution coefficient (
For phenol distribution coefficient for 100, for hydroquinone distribution coefficient is 9.
9, widely adopted by the factory, and obtained good effect in industrial applications, but its, much attention has been paid to the problem of high energy consumption is also one of the important reasons is residual solvent in solvent stripping tower stripping recovery, the vapor from the top of the tower in the form of azeotrope extraction, and MIBK formed azeotrope with water water quality score to 24.
3%, in the process of evaporation and condensation will increase energy consumption.
Therefore, it is of great significance to research new removing phenol extraction agent.
the determination of volatile phenol in wastewater containing phenol usually adopt national standard HJ502 -
After 2009 described distillation olfactory capacity method.
Measuring principle is: distillation in the volatile phenolics distilled from the waste water, and then join in the distillate containing excessive olfactory (
Produced by olfactory acid potassium and olfactory potassium)
Solution of phenolic compounds and smell generated three smell of phenol, and further with excess smell smell generation three smell of phenol.
For phenolic compounds react with excessive smell all, adding suitable amount of potassium iodide, the rest of the olfactory and potassium iodide, release the free iodine.
At the same time, potassium iodide and smell generation three smell of phenol reaction generated free iodine and three smell of phenol.
Finally, the titration with sodium thiosulfate solution to generate free iodine, consumption can be calculated according to its content of volatile phenol.
at present, there is no unified standard about the determination of total phenol.
Factory with the more is the smell of without distillation capacity method, with a 2009 gb HJ502 sniffing the distillation capacity method is waste water there is no different, in advance to remove the interference of wastewater components (
Oil, antioxidant, sulfide, aniline and other inorganic and organic reducing substances)
Later, directly with too much smell to determine reaction.
the experiment measured the volatile phenol and total phenol in waste water quality concentration respectively 8 450 mg/L and 12 700 mg/L, due to containing a large amount of ammonia, alkaline wastewater, pH = 8.
removing phenol waste water extraction experiment method removing phenol waste water extraction experiment is shown in figure 1 of 100 mL of homemade balance kettle.
The extraction agent and waste water according to certain comparison (
Join the balance kettle, mix with the magnet and magnetic stirrer intense mixing 1 h, and then put balance kettle in constant temperature water-bath water let stand for 4 h.
For oil phase and water phase after separating equilibrium, extracted with injector (at the bottom of the water phase
More than extraction phase)
The determination of volatile phenol and total phenol concentration.
For the convenience of liquid operations, tertiary cross-flow experiment in a separatory funnel.
the current coal gasification wastewater is usually after a first before extraction deacidification deamination rectifying column removal of ammonia and acid gas (
CO2 and h2s)
And so on, and then into the extraction process of call.
Into the extraction tower of wastewater pH advised to keep at 6.
5 an 8.
Between 0, to ensure that the extraction effect.
This paper introduces a new removing phenol extraction agent -
Methyl Ding Jijia ketone (
And on removing phenol MBK extraction performance were studied.
The experimental results show that although the MBK and MIBK as isomers, but its different ability in the extraction phenolics, service on the phenol extraction unit and MIBK ability, but on the extraction of polyphenol advantage is obvious.
Extraction of removing phenol conditions, explores the MBK, such as temperature, pH value, compared to the dephenolizing effect.
Experiment found that with the increase of temperature, MBK extraction dephenolizing effect gradually decline, but service at high temperature (
Still has high extraction ability;
And pH value of MBK extraction dephenolizing effect is larger, when the pH> 9.
After 0, extraction capacity fell sharply, in order to ensure the extraction efficiency of removing phenol, optimum pH = 6.
5 an 8.
Compared directly affects the size of the waste water after the extraction of total phenol concentration, at the same time, it's about solvent recovery, energy consumption through comparative tests under different than level 3 cross-flow after total phenol concentration and the corresponding energy consumption of solvent recovery, eventually determine appropriate than (
The range is R = 1:4 1:5.
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