JPS5834404B2 - Manufacturing method of ion exchange agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an inexpensive ion exchange agent using coal as a raw material.

Based on coal, mainly recycled humic acid,
Alternatively, several methods have been published in the past for producing ion exchangers by creating fluoric acid derivatives and using their functional groups.

That is, methods for obtaining regenerated humic acid by reacting coal with acid or alkali, or by subjecting it to appropriate oxidation are known.

For example, coal is treated with nitric acid to obtain nitrophic acid,
This is generally commercially available as an ion exchange agent or soil improvement agent.

However, in general, regenerated humic acid combines with alkali metals or becomes a soluble salt in an aqueous solution with a high pH and is eluted into the processing solution, resulting in undesirable phenomena such as coloration of the solution and increase in COD. Therefore, despite its low price, it is said to be difficult to apply to highly necessary processes such as the removal of heavy metal ions from wastewater.

On the other hand, in order to improve this drawback, nitrophic acid was added to CMC.
A method has been proposed to reduce its solubility by binding with (carboxy methyl cellulose).

However, even with this method, it is difficult to completely suppress elution in the high pH region.

The present invention relates to a method for producing an industrially valuable solid ion exchange agent by fixing regenerated humic acid obtained from coal and making it insoluble through simple operations.

There are various operations for producing recycled humic acid from coal, but the process of catalytically reacting a small amount of alkali as an aqueous solution is simple and inexpensive.

In the present invention, recycled phosphoric acid is not eluted and liberated from coal and extracted as a highly pure substance, but the coal is swollen and expanded with an alkaline solution to increase the internal surface area of its particle structure. Since the goal is to expose many humic acid functional groups fixed on the surface, it is optimal to dissolve the corresponding alkali in an amount of water sufficient to swell the coal and bring it into contact with the coal.

The reaction of swelling coal with an aqueous alkaline solution and producing regenerated humic acid, which is the first stage treatment of the present invention, is almost completed in a few minutes to several tens of minutes, but at the end of the process, most of the added water becomes retained water inside the swollen coal. Therefore, it is desirable that the amount of free moisture outside the coal particles is small.

Therefore, the regenerated alkali metal salt of humic acid produced by the reaction between coal and aqueous alkali solution becomes partially soluble.
Even if it leaches into the aqueous solution, most of it remains in the retained water of the swollen coal.

In the case of caustic powder, the amount of alkali used in the first stage is in the range of 5 to 40% by weight based on dry charcoal, and the amount of water used is 40% by weight.
~200% weight is common.

In the second stage of the present invention, this swollen charcoal is heat-treated for several hours to stabilize the regenerated humic acid functional groups on the surface, and the regenerated humic acid eluted into the retained water of the swollen charcoal in the casing. Salts are also effectively immobilized on the internal surface by chelation or dehydration condensation reactions, increasing the ion exchange capacity of the coal particles.

If this second-stage treatment is not performed and the first-stage alkaline aqueous solution treatment reaction is completed and then washed directly with water, a large amount of soluble regenerated humate will flow out, resulting in a loss of functional groups and a decrease in ion exchange ability. do.

The elution of the soluble regenerated phosphate salt has a slow internal diffusion rate and a high degree of coloration, so the washing process takes a lot of time and
Washing water is required, which is a big disadvantage.

On the other hand, if the second stage heat treatment of the present invention is performed, the functional groups are stabilized with a simple operation, and even when this is washed and commercialized, the elution of recycled fluoric acid is extremely small. It is not only economical as it can be completed with a small amount of water.
Processing of the washing wastewater discharged from the process is simple and profitable, and the exchangeability of finished products is sufficiently large.

The second heat treatment is generally carried out at 600 to 2000 C1 wet or dry for 1 to 20 hours.

As described above, according to the present invention, an inexpensive ion exchange agent that retains high performance and stable humic acid functional groups on its expanded internal surface can be produced without secondary pollution using simple process equipment. be able to.

Since this product is inexpensive and can be obtained in suitable granular form, it is thought that it can make a great contribution, especially to the collection of heavy metal ions in industrial wastewater.

As the example coal, Ibaraki Bokai coal, which is a young lignite, was adjusted to 10 to 32 mesh, and 15 parts of caustic soda based on the bone dry weight of the coal was dissolved in water of the same <100% weight and brought into contact. Perform the first stage alkali treatment, and then
The heated state was maintained at 05° C. for 3 hours, and the second stage of functional group stabilization treatment was performed.

When the product was washed with an amount of water three times the weight of coal, no brown dissolution coloring of the regenerated phosphate was observed, and its exchange capacity was as follows.

Claims (1)

[Claims] 1 The first step is to treat coal with an alkaline solution, and the alkali-treated coal is heat-treated at a temperature of 60 to 200'C to make the active groups generated in the first step insoluble in water and stabilize it. A method for producing an ion exchange agent, comprising a second step.