JPS62286539A - Phosphate ion adsorbent and its preparation - Google Patents

Abstract

PURPOSE:To increase the adsorbing capacity of a phosphate ion at pH1-6, by preparing a phosphate ion adsorbent by supporting one or more kind of hydrated oxide of one or more kind of a metal selected from Ti, Zr, Sn, and lanthanide by activated carbon. CONSTITUTION:Activated carbon is impregnated with an aqueous solution of a soluble salt of one or more kind of a metal selected from Ti, Zr, Sn and lanthanide. Subsequently, the impregnated activated carbon is dried and the aforementioned soluble salt is converted to hydrated oxide through the reaction with ammonia or NaOH to prepare a phosphate ion adsorbent. It is pref. to further age the aforementioned hydrated oxide at 70-150 deg.C and the wt. ratio of the hydrated metal oxide to activated carbon is pref. set to 0.05-0.8. As the soluble metal salt, TiCl4, Ti(SO4)2, ZrOCl2, ZrO(NO3)2, SnCl, LCl3 and LNO3 (L is lanthanide) is pref.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a phosphate ion adsorbent and a method for producing the same [Prior Art] At present, the eutrophication phenomenon of closed water bodies including inland lakes and marshes has become a serious social problem.

One of the causes of this phenomenon is the influx of phosphate ions, and reducing the removal of phosphate ions from wastewater from surrounding facilities is an important issue that must be resolved immediately.

By the way, the current method for removing phosphate ions from wastewater is the so-called coagulation-sedimentation method, in which aluminum salts, iron salts, etc. are added to the wastewater, and the hydrated oxides of these metals adsorb and precipitate the phosphate ions. However, this method essentially generates a large amount of sludge, which requires treatment, and is not a satisfactory method.

On the other hand, hydrated oxides of metals such as titanium, zirconium, tin, or lanthanides have anion exchange properties and have particularly strong adsorption properties for phosphate ions, so adsorption using hydrated oxides of these metals is difficult. However, the hydrated oxides of the metals mentioned above are generally in the form of a gel, and filtration or adsorption/desorption of phosphate ions is not easy. Add iron salt, and add titanium along with hydrated magnetite.
Adsorbents have been developed in which hydrated oxides such as zirconium are co-precipitated, dried and then granulated using polyester or polyurethane resin [JP-A-56-118734 and 57-50543, and Tamatsuki, Yano and Hone. (Refer to Proceedings of the National Urban Cleaning Research Conference (1986-2)) However, the manufacturing method for this adsorbent is not necessarily easy;
Furthermore, since the granules are granulated using a polymer, it is thought that some of the surface of the hydrated metal oxide is covered with the resin, which impairs its ability to adsorb phosphate ions.

[Problem that the invention seeks to solve]

The present inventors have carried out extensive studies to develop a phosphate ion adsorbent that does not generate sludge after adsorbing phosphate ions and can be easily manufactured in a relatively soft manner.As a result, the present invention has been developed. It is almost complete.

[Means for solving problems]

According to the invention, at least 1F! selected from titanium, zirconium, tin and lanthanides! The present inventor provides a phosphate ion adsorbent comprising hydrated oxides of metals supported on activated carbon. surface °
We have succeeded in developing an adsorbent that can withstand the adsorption and desorption of hyrate ions. The weight ratio of metal oxide to activated carbon is 0.05
The adsorbent of the present invention is essentially equivalent to activated carbon, and can be produced in various particle sizes or shapes such as granules, crushed or powdered, and has an appearance similar to that of activated carbon. As such, it has great mechanical strength, is acid resistant and alkali resistant, and can repeatedly adsorb and desorb phosphate ions, and is fully compatible with the operating conditions of regular industrial adsorption equipment such as fixed beds and fluidized beds. can be done. Therefore, the adsorption and desorption performance of phosphoric acid is superior to any of the previously existing adsorbents, and the manufacture of the adsorbent is simple.

The adsorbents of the present invention generally include soluble groups of metals selected from titanium, zirconium, tin and lanthanides, such as TICt4, which can be produced by the following method.
, TI (804)2 p Zr0Ct2 , ZrC2
41Zr (NO3)! , Zr0(SQ, ), Zr0
(CH3COO),.

Using 5nCt4, lanthanide chloride or nitrate, etc., an aqueous solution of these alone or a mixture of two or more is prepared. The concentration of the solution depends on the bath solubility of the salt used (0.2 to 2.0 molar concentration is appropriate. However, this concentration does not need to be strict, and metals in the urine solution are Although it is acceptable to add some inorganic acid or organic salt to prevent hydrolysis, it is not advantageous for subsequent operations to add an excess of such acid.

Add dry activated carbon at a rate of approximately 1 to 1.3 kf to 1 ton of this solution and mix to make the activated carbon adsorb the solution.The mixing ratio of the solution and activated carbon does not necessarily have to be this value, but the activated carbon If the ratio is large, there is a risk that the adsorption will be insufficient or uniform, and if the amount of solution is large, the drying operation will require a special patent application, making it uneconomical. In this case, the heating temperature is about 90° C., and the moisture removal rate is targeted to be about 70 degrees of the added water, but neither condition needs to be strict. However, drying conditions where a large amount of the salt adsorbed in this drying process oozes out and crystallizes on the surface of the activated carbon particles are unfavorable.Next, the activated carbon is left in an ammonia gas atmosphere to absorb ammonia gas. Thus, the hydrated oxides of metals that have been occluded in advance in the pores of the activated carbon are not easily eluted from the activated carbon. In this operation, it is better to introduce ammonia gas into a sealed container while smothering the activated carbon, but the purpose can also be achieved simply by placing concentrated ammonia water in one corner of the container. .

It is more effective to introduce ammonia gas under pressure after completely reducing the pressure in the 1L container, but a neutralization reaction takes place within the pores of activated carbon, which is accompanied by heat generation, which may occur when handling large quantities. Q. However, the heat of reaction must be taken into consideration.
This heat generation can be easily controlled by adjusting the amount of ammonia gas introduced.It is also possible to generate hydrated oxides by using an aqueous alkali solution instead of ammonia gas, but this is more economical in terms of operation. It's good on target.

If desired, it is preferable to fully heat the activated carbon in which the hydrated metal acid or arsenate has been fixed in its pores to ripen the hydrated oxide. At this time, if ignited, there is a danger that dehydration will progress too much and the phosphate ion adsorption capacity will be reduced.
It is appropriate to heat it only to about 0-100°C. Afterwards, it is washed with water to remove soluble ammonium salts generated as a result of the reaction, and if necessary, it is once dried and stored for use.

The phosphate ion adsorbent of the present invention is composed mainly of zirconium hydrated oxide, and has a pH value similar to that of previously reported zirconium hydrated oxide adsorbents.
The adsorption capacity for phosphate ions is large in the acidic range of pH 1 to 6, and it is removed on the alkaline side (pH > 9). Therefore, all of the water to be treated must be made slightly acidic and passed through the column filled with this adsorbent. The phosphate ions can be adsorbed using the alkaline solution, and then the phosphate ions can be desorbed and recovered using an alkaline solution, and the adsorption column can be regenerated.

The present invention will be further explained below with reference to Examples.

Example 1 1.6 molar aqueous solution of zirconyl chloride 1t'ii! 14f
i do This aqueous solution contains 146? Coconut grain activated carbon (20X
48 mesh) is added and mixed to adsorb the aqueous solution. Next, this activated carbon is dried at 90°C. Drying ends when about 70% of the water has been removed.Next, this activated carbon is placed in an airtight container containing Asimonia water.
After the reaction with ammonia for 5 hours with occasional stirring, the activated carbon is aged at 100° C. for 2 hours.

Next, the product 7 produced by the reaction was washed with water to remove the hyammonium. After rinsing with water, the adsorbent was dried again at 100°C to obtain an adsorbent. This aqueous solution contains 1462 ions as Zr. Coconut grain activated carbon (20X48
Messier) 800F is added and mixed to adsorb the aqueous solution. Next, this activated carbon is dried at a total temperature of 90°C. Drying is completed at time t, when approximately 70 g of water has been removed.Next, 3.3 molar aqueous sodium hydroxide solution lt is poured into the activated carbon.
The mixture was mixed and reacted by immersion for 2 hours, and after the reaction was completed, the mixture was aged on activated carbon at 100° C. for 2 hours. Next, in order to remove fctxr arsenium produced by the reaction and excess sodium dispersion, the solution was washed with water until the pH of the washing solution became neutral, and then dried again at 100° C. to obtain an adsorbent.Example 3 Chlorination 1 t of an aqueous solution of a mixture of 0.8 mol of zirconyl and 0.8 mol of titanium tetrachloride is prepared. This aqueous solution contains 73? as Zr'? In addition, 389 ions of Ti are included. Coconut grain activated carbon (20
X48 mesh) soor is added and mixed to adsorb the aqueous solution. Next, this activated carbon is dried at 90°C. At the end of drying, approximately 70% of the water has been removed.
This activated carbon was placed in a sealed container containing aqueous ammonia and allowed to react with ammonia for 5 hours with occasional stirring. After the reaction is completed, it is aged in an activated carbon tube at 100°C for 2 hours.

Next, the mixture was washed with water to remove ammonium chloride generated by the reaction. After washing with water, the adsorbent was dried again at 100°C to obtain an adsorbent.

Example 4 Phosphate ion 7 learned by rA using sodium phosphate
0.5 NHCt in the test solution containing 500 ppm "f gold
Or add 0.5 N NaOHR solution until the pH is about 1.
Aqueous solution adjusted to have a concentration of 3.5, 7, 9.11 or 13 was prepared by loo+nt. Next, Example 1
The adsorbent obtained was crushed and passed through 150 meshes.
4 and added 400μ of each to the above aqueous solution, and after shaking for 2 hours, filtered with FM, and measured the PIT and phosphate ion concentration of solution F. At this time, the phosphate ion of the adsorbent Table 1 shows the relationship between adsorption amount and pH.

Table 1 0.7 500 86 1041.8
94 1022.8 1 i3
6 913.9 1 176 81
4.7 #230 685.8
1 278 557.0 #3
46 388.6 1 414 2
29.5 1 432 1711, l
#460 1012.3t
474 6 Example 5 The adsorbent obtained in Example 1 was pulverized to obtain a 150 mesh product.Next, an aqueous solution containing 500 ppm of phosphate ions prepared using sodium phosphate was prepared.
Add the above adsorbent powder to O1Rt (pH=5) at 0.2f,
0.4F, 0.6P maku is 0.82 Mayuzumi, plus 2
After shaking for a period of time, the phosphate ion adsorption t of the adsorbent was measured, and the results are shown in Table II-2.

Table 2 0.2 500 355 730.4,
1228 680.6 1 100
670.8 8 62 Example 6 The adsorbent obtained in Example 1 was filled into a glass tube with an inner diameter of L2.3wφ so that the bed height was 10c1n, and the filling amount was 12
m (6F). An aqueous solution containing phosphate ions (lOOppm(p)I=5) made from sea bream using phosphate-sodium sound was passed through this at 5 VIO, and the phosphate ion concentration in the passing liquid was measured. Oral canal shown in Table 43 Table 3 0.5 Detected none 1.0 Not detected 1.58 2.08 2.5 13 3.0 19 Example 7 After adsorbing phosphate ions in Example 6, the adsorbent (Total phosphate ion adsorption tFi252Qc with 3t of liquid flowing)
Aqueous solution of N NaOH (50 met SV 1) was passed through to remove phosphate ions. We measured the phosphate ions in the desorbed solution and found that the amount of phosphate ions adsorbed was approximately 98%.
After desorption, the adsorbent 1c 0
．． After regenerating by passing a 50 dt-3Vl11 5N H2804 aqueous solution, adsorption was carried out by passing a liquid under the same conditions as in Example 6. Hereafter, repeat regeneration and adsorption 7
tQ The adsorption results at this time are shown in Table 4.

Claims (1)

[Scope of Claims] 1. A phosphate ion adsorbent comprising activated carbon supporting a hydrated oxide of at least one metal selected from titanium, zirconium, tin, and lanthanide. 2. Weight ratio of hydrated metal oxide to activated carbon is 0.05
The adsorbent according to claim 1, which has a molecular weight of ˜0.8. 3. The adsorbent according to claim 1, which is regenerated by an alkaline solution. 4. Activated carbon is impregnated with an aqueous solution of a soluble salt of at least one metal selected from titanium, zirconium, tin, and lanthanide, and after drying, the soluble salt is reacted with ammonia or NaOH to form a hydrated oxide. A method for producing a phosphate ion adsorbent, comprising: 5. The soluble salts of the metals are TiCl_4, Ti(SO_
4)_2, ZrOCl_2, ZrCl_4, ZrO(N
O_3)_2, ZrOSO_4, ZrO(CH_3CO
O)_2, SnCl_4, LCl_3 and LNO_3
5. The method according to claim 4, wherein L represents a lanthanide. 6. The method of claim 4, wherein the hydrated oxide is then aged at 70-150°C.