Method for precipitating calcium and magnesium in industrial wastewater

Abstract

The invention provides a method for precipitating calcium and magnesium in industrial wastewater, which comprises the following steps: mixing prepared alkoxyphenylacetic acid serving as an organic precipitating agent with an alkaline compound and industrial wastewater containing calcium and magnesium ions, and conducting precipitating; conducting solid-liquid separation to obtain a solid precipitate containing calcium and magnesium and a water phase; under the condition that COD in the water phase is not increased, enabling residual calcium and magnesium in the industrial wastewater to reach the minimum standard required by an enterprise; and eluting the solid precipitate containing calcium and magnesium by using an acid solution to obtain an eluate rich in calcium and magnesium and an organic precipitant. The organic precipitating agent provided by the invention has a very good precipitating effect on ions which can bring permanent hardness to calcium, magnesium and the like, and is very suitable for removing calcium and magnesium ions in industrial wastewater so as to achieve the purpose of softening the wastewater; experimental results show that when the organic precipitating agent provided by the invention is used for precipitating industrial wastewater containing calcium and magnesium, the precipitating speed is high, the total precipitating rate of calcium and magnesium is greater than 95%, the recycling effect of the organic precipitating agent is good, and the production cost can be greatly reduced.

Description

Technical field

[0001] The invention belongs to the field of industrial wastewater treatment, and particularly relates to a method for precipitating calcium and magnesium in industrial wastewater. Background technique

[0002] my country is rich in rare earth resources, with rare earth reserves and output ranking first in the world. However, due to factors such as technology and geography, the wastewater pollution generated during the smelting process of rare earths has not yet been effectively controlled. For example, in the process of roasting monazite and bastnaesite in concentrated sulfuric acid, the ammonium sulfate wastewater produced has become one of the main sources of ammonia nitrogen pollution in the Baotou section of the Yellow River. Ammonium sulfate wastewater can be recycled through reverse osmosis concentration and stripping method to recover the ammonia, so that the wastewater can be recycled, in order to achieve "zero discharge". However, the content of calciu...

Examples

Embodiment 1

[0048] 1) Preparation of 1,1,3,3-tetramethylbutylphenoxyacetic acid:

[0049] 100 grams of absolute ethanol and 48.4 grams (0.21 mol) of sodium 1,1,3,3-tetramethylbutylphenol were added to the reaction vessel. Turn on the stirring and heating, heat up to 110°C, and slowly add 37.8 grams (0.32 mol) of sodium chloroacetate into the reaction vessel. After 1.5 hours of reaction, cool to room temperature, distill the solvent under reduced pressure on the obtained reaction product, and then add 50mL 6mol / L hydrochloric acid solution for acidification. The acidification temperature is 30℃, the acidification time is 5min, and the acidification product is washed with water 3 After the second time, it was distilled under reduced pressure at 160°C to obtain 1,1,3,3-tetramethylbutylphenoxyacetic acid.

[0050] The 1,1,3,3-tetramethylbutylphenoxyacetic acid prepared in this embodiment is subjected to acid-base titration and nuclear magnetic detection, and the purity is greater than 99%, and it...

Embodiment 2

[0062] 1) Preparation of 2,6-Dimethylheptylphenoxyacetic acid:

[0063] Add 100 grams of absolute ethanol and 0.21 mol of sodium 2,6-dimethylheptylphenol to the reaction vessel. Turn on stirring and heating, heat up to 110°C, and slowly add 0.32 mol of sodium bromoacetate into the reaction vessel. After 1.5 hours of reaction, cool to room temperature, distill the solvent under reduced pressure on the obtained reaction product, and then add 50mL of 6mol / L hydrochloric acid solution for acidification. The acidification temperature is 30℃ and the acidification time is 5min. Wash the acidified product with water 3 After the second, it was distilled under reduced pressure at 140°C to obtain 2,6-dimethylheptylphenoxyacetic acid.

[0064] The 2,6-dimethylheptylphenoxyacetic acid prepared in this embodiment was subjected to acid-base titration and nuclear magnetic detection, and the purity was greater than 99%, and it had a structure of formula (I).

[0065] 2) Removal of calcium and magne...

Embodiment 3

[0069] 1) Preparation of 4,4'-isopropylidene diphenoxyacetic acid:

[0070] Add 100 grams of absolute ethanol and 45.7 grams (0.20 mol) of 2,2-bis(4-hydroxyphenyl)propane to the reaction vessel. Turn on stirring and heating, increase the temperature to 110°C, and slowly add 58.3 g (0.5 mol) of sodium chloroacetate into the reaction vessel. After 1.5 hours of reaction, cool to room temperature, distill the solvent under reduced pressure on the obtained reaction product, and then add 80mL of 6mol / L hydrochloric acid solution for acidification. The acidification temperature is 30℃, the acidification time is 5min, and the acidification product is washed with water 3 After the second, vacuum distillation at 160°C, 4,4'-isopropylidene diphenoxyacetic acid was obtained.

[0071] The 4,4'-isopropylidene diphenoxyacetic acid prepared in this example was subjected to acid-base titration and nuclear magnetic detection, and the purity was greater than 99%, and it had the structure of formula ...

Technical field

[0001] The invention belongs to the field of industrial wastewater treatment, and particularly relates to a method for precipitating calcium and magnesium in industrial wastewater. Background technique

[0002] my country is rich in rare earth resources, with rare earth reserves and output ranking first in the world. However, due to factors such as technology and geography, the wastewater pollution generated during the smelting process of rare earths has not yet been effectively controlled. For example, in the process of roasting monazite and bastnaesite in concentrated sulfuric acid, the ammonium sulfate wastewater produced has become one of the main sources of ammonia nitrogen pollution in the Baotou section of the Yellow River. Ammonium sulfate wastewater can be recycled through reverse osmosis concentration and stripping method to recover the ammonia, so that the wastewater can be recycled, in order to achieve "zero discharge". However, the content of calciu...

Examples

Embodiment 1

[0048] 1) Preparation of 1,1,3,3-tetramethylbutylphenoxyacetic acid:

[0049] 100 grams of absolute ethanol and 48.4 grams (0.21 mol) of sodium 1,1,3,3-tetramethylbutylphenol were added to the reaction vessel. Turn on the stirring and heating, heat up to 110°C, and slowly add 37.8 grams (0.32 mol) of sodium chloroacetate into the reaction vessel. After 1.5 hours of reaction, cool to room temperature, distill the solvent under reduced pressure on the obtained reaction product, and then add 50mL 6mol / L hydrochloric acid solution for acidification. The acidification temperature is 30℃, the acidification time is 5min, and the acidification product is washed with water 3 After the second time, it was distilled under reduced pressure at 160°C to obtain 1,1,3,3-tetramethylbutylphenoxyacetic acid.

[0050] The 1,1,3,3-tetramethylbutylphenoxyacetic acid prepared in this embodiment is subjected to acid-base titration and nuclear magnetic detection, and the purity is greater than 99%, and it...

Embodiment 2

[0062] 1) Preparation of 2,6-Dimethylheptylphenoxyacetic acid:

[0063] Add 100 grams of absolute ethanol and 0.21 mol of sodium 2,6-dimethylheptylphenol to the reaction vessel. Turn on stirring and heating, heat up to 110°C, and slowly add 0.32 mol of sodium bromoacetate into the reaction vessel. After 1.5 hours of reaction, cool to room temperature, distill the solvent under reduced pressure on the obtained reaction product, and then add 50mL of 6mol / L hydrochloric acid solution for acidification. The acidification temperature is 30℃ and the acidification time is 5min. Wash the acidified product with water 3 After the second, it was distilled under reduced pressure at 140°C to obtain 2,6-dimethylheptylphenoxyacetic acid.

[0064] The 2,6-dimethylheptylphenoxyacetic acid prepared in this embodiment was subjected to acid-base titration and nuclear magnetic detection, and the purity was greater than 99%, and it had a structure of formula (I).

[0065] 2) Removal of calcium and magne...

Embodiment 3

[0069] 1) Preparation of 4,4'-isopropylidene diphenoxyacetic acid:

[0070] Add 100 grams of absolute ethanol and 45.7 grams (0.20 mol) of 2,2-bis(4-hydroxyphenyl)propane to the reaction vessel. Turn on stirring and heating, increase the temperature to 110°C, and slowly add 58.3 g (0.5 mol) of sodium chloroacetate into the reaction vessel. After 1.5 hours of reaction, cool to room temperature, distill the solvent under reduced pressure on the obtained reaction product, and then add 80mL of 6mol / L hydrochloric acid solution for acidification. The acidification temperature is 30℃, the acidification time is 5min, and the acidification product is washed with water 3 After the second, vacuum distillation at 160°C, 4,4'-isopropylidene diphenoxyacetic acid was obtained.

[0071] The 4,4'-isopropylidene diphenoxyacetic acid prepared in this example was subjected to acid-base titration and nuclear magnetic detection, and the purity was greater than 99%, and it had the structure of formula ...

Images