JP2009022877A - Adsorbent for phosphorus and method for removing phosphorus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adsorbent for phosphorus capable of being re-used by selectively dissolving the adsorbed phosphorus and being sufficiently used even at neutrality, and a method for removing phosphorus from a liquid to be treated using the adsorbent. <P>SOLUTION: A capacity of the liquid to be removed is determined and a concentration of phosphorus contained in the liquid to be removed is determined by a measurement value or an estimated value. Based on the results, an addition amount of the adsorbent in which zirconium is bonded to a carrier containing pectinic acid as a main component is determined. The adsorbent in the obtained addition amount is thrown into the liquid to be removed and the mixture is stirred for 10 hours or more to adsorb phosphorus (phosphoric acid) in the liquid to be removed to the adsorbent. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an adsorbent that adsorbs phosphorus contained in a liquid to be removed, such as domestic wastewater or livestock excreta, and a liquid to be removed using the adsorbent in order to prevent phosphorus from being released into the environment. The present invention relates to a method for removing phosphorus from water.

Liquids containing phosphorus (phosphoric acid) such as domestic wastewater or livestock excreta, when released into the environment while containing phosphorus, will lead to eutrophication that leads to environmental destruction, so the cost can be minimized Therefore, it is required to remove phosphorus without requiring it.
By the way, the present inventors have disclosed the following adsorbents in Patent Document 1 described later.

  That is, by adding calcium hydroxide and water to the juice residue of mandarin orange or apple, and crushing the juice residue in this alkaline solution, while generating pectin acid from the pectin contained in the juice residue, After making calcium ion react with the produced pectic acid and gelling, it is washed with water until it becomes almost neutral, and the dried product is dried at a temperature of 40 ° C to 80 ° C. A dry carrier is obtained. By suspending this dry carrier in a ferric ion solution having an appropriate concentration, a gel-like carrier is generated from the dry carrier, and ferric ions are adsorbed and bound to this carrier to obtain an adsorbent.

The inventors of the present invention have studied various adsorption capacities of such adsorbents and have found that phosphorus can be adsorbed in addition to arsenic.
Therefore, in order to remove phosphorus from the liquid to be removed using such an adsorbent, an appropriate amount of adsorbent is added to the liquid to be removed and stirred for an appropriate period of time so that the phosphorus in the liquid to be removed is adsorbed to the adsorbent. After that, phosphorus is removed from the liquid to be removed by solid-liquid separation of the adsorbent and the liquid to be removed by filtration or subsidence.

Alternatively, the pressure-resistant cylinder is filled with the adsorbent, and the liquid to be removed is allowed to flow from one end side to the other end of the cylinder to adsorb phosphorus in the liquid to be adsorbed on the cylinder. Therefore, it was considered to remove phosphorus from the liquid to be removed.
Japanese Patent Laid-Open No. 2004-267805

  However, such an adsorbent is as cheap as possible because it can be produced by a relatively simple process using squeezed residue as industrial waste, but has the following problems. It was.

  That is, since ferric iron precipitates in an environment exceeding pH 3.0, the pH range in the case of binding ferric ions to a carrier obtained by gelling pectic acid is about pH 2.0 to pH 2.5. Narrow, and therefore, the binding force between the carrier and the ferric ion adsorbed thereto is weak.

On the other hand, since the adsorption power of phosphorus to ferric iron is relatively strong, phosphorus cannot be desorbed from ferric iron under mild conditions, and an aqueous hydrochloric acid solution of about 1M is added to the adsorbent adsorbing phosphorus. As a result, phosphorus can be eluted from the adsorbent, but the ferric ion bound to the carrier is also eluted in a state bound to phosphorus by the operation, so that the adsorbent cannot be reused. There was a problem.
Further, when phosphorus removed from the liquid to be removed is used, post-treatment for separating and removing ferric iron has to be performed, and there is a problem that post-treatment requires time, cost, and cost.
By the way, as an adsorbent for removing phosphorus from a liquid to be removed, a zirconium ferrite-based adsorbent (for example, Seven Tol (registered trademark) P (Takeda Pharmaceutical Co., Ltd.)) is commercially available.

  However, in such an adsorbent, as will be described later, the amount of phosphorus adsorbed is good in the strongly acidic region, but decreases toward the weakly acidic region. Since the amount is reduced to about 1/2 of the amount, there is a problem that it is not suitable for use near neutrality.

  The present invention has been made in view of such circumstances, and it is possible to selectively elute adsorbed phosphorus and reuse it, and to sufficiently use even in the vicinity of neutrality And a method for removing phosphorus from the liquid to be treated using the adsorbent.

  (1) The adsorbent according to the present invention is formed by appropriately bonding a metal to a carrier, and adsorbing phosphorus contained in a liquid to be removed, and by binding zirconium to a carrier containing pectic acid as a main component. It is characterized by.

  For example, a gel-like carrier containing pectin acid as a main component is obtained by reacting pectin acid with formaldehyde to crosslink pectin acid. This carrier may be dried. By treating this carrier with a zirconium solution having an appropriate concentration adjusted to about pH 2 to pH 6, an adsorbent that adsorbs and binds zirconium to the carrier to adsorb phosphorus can be prepared.

  The treatment with the zirconium solution may be, for example, a batch method in which a carrier is added to the zirconium solution and stirred, or a column method in which the zirconium solution is passed through a column packed with the carrier.

  The adsorbent in which zirconium is bound to the above-mentioned carrier can sufficiently adsorb phosphorus in a wide pH range from the acidic region to the basic region. Therefore, in most cases, the operation of removing phosphorus from the liquid to be removed such as domestic wastewater or livestock excreta can be performed without adjusting the pH.

  On the other hand, by treating the adsorbent adsorbing phosphorus with a sodium hydroxide solution having an appropriate concentration, it was possible to elute phosphorus from the adsorbent without desorbing zirconium from the support. Since the adsorbent from which the adsorbed phosphorus is eluted can adsorb phosphorus again, such an adsorbent can be used repeatedly.

(2) Moreover, the adsorbent according to the present invention is characterized in that the carrier is prepared using mandarin juice residue or apple juice residue as a raw material.
The citrus juice residue and apple juice residue contain a relatively large amount of pectin, and pectin acid can be produced by treating them with a treatment solution such as sodium hydroxide solution. Such pectic acid can be gelled by adding a metal ion such as Ca or Mg, and can be used as a carrier.
The adsorbent in which zirconium is bonded to such a carrier can sufficiently adsorb phosphorus in a wide pH range of pH 2 to pH 10.
On the other hand, tangerine juice residue and apple juice residue are industrial wastes. In addition to being able to produce adsorbents at low cost, industrial wastes can be used effectively.

(3) On the other hand, in the method for removing phosphorus according to the present invention, in the method for removing phosphorus from the liquid to be removed by adsorbing phosphorus in the liquid to be removed to the adsorbent, the method (1) or (2) The adsorbent described is used.
The phosphorus in the liquid to be removed can be adsorbed by the adsorbent described above by a batch method in which the adsorbent is added to the liquid to be removed and stirred, or the liquid to be removed is passed through a column packed with the adsorbent. It can also be carried out by a flowing column method.
At this time, since the adsorbent described in the above (1) or (2) is used as the adsorbent, the above-described effects are exhibited.

(4) Moreover, the phosphorus removal method according to the present invention is characterized in that the adsorbent adsorbing phosphorus is treated with a sodium hydroxide solution having an appropriate concentration to elute phosphorus from the adsorbent.
For example, a sodium hydroxide solution of about 0.2M can be used as an eluent for eluting phosphorus from the adsorbent.

  In the elution of phosphorus, since the phosphorus released from the zirconium is eluted while the zirconium remains bonded to the carrier, the phosphorus can be easily recovered from the eluent and directly applied to the soil fertilizer etc. Can be used.

(Embodiment of the present invention)
Embodiments according to the present invention will be described below.
(Preparation of carrier)
A method for preparing an adsorbent carrier using tangerine juice residue will be described.

  3 g of calcium hydroxide and 10 ml of water are added to 150 g of wet citrus juice residue generated at a mandarin orange juice factory, and crushing is performed for about 30 minutes using a sample mill SK-M10 type crusher (Kyoritsu Riko Co., Ltd.). did. Transfer the resulting processed product into a suitable container, add 500 ml of water and stir at room temperature for about 24 hours to saponify the pectin contained in the tangerine juice residue to form a calcium salt of pectic acid. Gelled.

  The liquid material was transferred onto a sieve having an appropriate diameter, and the sizes of the gel particles were made uniform. The gel and liquid that passed through the sieve were collected in another container. An appropriate amount of water was added to the collected material and stirred, and then allowed to stand to sink the gel carrier, and the supernatant was discarded to wash the carrier. And after repeating this washing | cleaning operation until the pH of a supernatant becomes neutral, a support | carrier is filter-separated using the sieve which has an eye with a diameter of about 300 micrometers, for example, for example, 40 to 80 degreeC using a convection dryer. Drying was performed at a temperature of ° C, preferably 50 ° C to 70 ° C, to obtain a powdery dry carrier.

  By using such a dry carrier, even when the dry carrier is suspended in liquids having various pHs between pH 1 and pH 8, release of organic carbon from the gel is suppressed, and the carrier The gel strength can be improved.

Next, a method for preparing an adsorbent carrier using apple juice residue will be described.
50 ml of water was added to 200 g of wet apple juice residue generated in an apple juice factory, and the mixture was crushed using a home mixer. After the obtained processed product was transferred into an appropriate container, 6 g of calcium hydroxide was added and stirred at room temperature for about 48 hours.

This was again transferred to a home mixer and crushed for about 30 minutes, then transferred to a suitable container, 500 ml of water was added, and the mixture was stirred at room temperature for about 24 hours.
And as before, filtration, washing | cleaning operation of a support | carrier, and drying operation were performed, and the powdery dry support | carrier was obtained.

  In addition, squeezed residue such as Satsuma mandarin, hassaku, and red pepper can be used as the mandarin juice residue, and squeezed residue such as Tsugaru, Wang Lin, and Jonah can be used as the apple juice residue.

  In addition, the above-described squeezed residue, calcium hydroxide and water amounts, processing time, pulverizer and dryer can be appropriately changed according to the processing scale. For example, a spray dryer can be used instead of the convection dryer.

On the other hand, it can be gelled by cross-linking pectinic acid using formaldehyde, and this can be used as a carrier.
That is, 2 ml of a mixture of 0.5 ml of concentrated hydrochloric acid and 99.5 ml of 35% formaldehyde aqueous solution was added to 5 g of pectic acid powder (Katayama Chemical Co., Ltd.), and further 3 ml of distilled water was added and mixed at room temperature. Let stand for 2 hours.

  Next, it is heated at 105 ° C. for 3 hours to crosslink and dry the pectic acid to obtain a powder. The obtained powder was suspended in 0.1M sodium hydroxide solution to be gelled and washed, and the supernatant was discarded by a decantation method, and then washed by injecting 0.1M hydrochloric acid solution, Discard the supernatant by decantation. And after washing | cleaning with a basic solution and an acidic solution, washing | cleaning is repeated until it becomes neutral with distilled water, for example, vacuum-drying can obtain a dry support | carrier.

(Preparation of adsorbent)
In the adsorbent according to the present invention, the adsorbent is prepared by binding zirconium ions to the carrier thus prepared.
FIG. 1 is a graph showing the influence of pH when zirconium ions are bound to a carrier according to the present invention, the horizontal axis represents the pH of the solution after adsorption of zirconium, and the vertical axis represents the zirconium bound to the carrier. Each percentage is shown.

  Zirconium oxychloride octahydrate (Wako Pure Chemical Industries, Ltd.) is dissolved in pure water so that the initial concentration of zirconium is 25 mg / l, and at a pH of 0.5 to H6 using hydrochloric acid solution or sodium hydroxide solution. A zirconium solution having various pH values was obtained by adjusting the pH to 0.0, and 25 mg of a dry carrier prepared from citrus juice residue was added to each of the obtained zirconium solutions, and then adjusted to 15 ml.

  Then, after shaking at 30 ° C. for 24 hours, the supernatant is collected, and the concentration of remaining zirconium is measured using an ICP atomic emission spectrometer (ICPS500 type, Shimadzu Corporation) to obtain a percentage with respect to the initial concentration. It was.

  As is clear from the graph shown in FIG. 1, in the carrier according to the present invention, zirconium ions were bound approximately 100% in the range of pH 2.0 to pH 6.0. From this, it can be seen that the bond strength between the carrier mainly composed of pectinic acid prepared as described above and zirconium ions is high.

  FIG. 2 is a graph showing the relationship between the zirconium concentration and the amount of zirconium ions bound to the carrier according to the present invention, wherein the horizontal axis represents the remaining zirconium concentration and the vertical axis represents the amount of zirconium bound per kg of dry carrier. Each is shown.

  25 mg of dry carrier prepared from tangerine juice residue was added to 15 ml of zirconium solution (pH 3.0) prepared to various concentrations from 0.25 mmol / l to 10 mmol / l and shaken at 30 ° C. for 24 hours. Thereafter, the supernatant is collected, and the concentration of remaining zirconium is measured using an ICP atomic emission spectrometer (ICPS500 type, Shimadzu Corporation), and dried based on the amount of zirconium reduced from the initial concentration of each zirconium solution. The amount of zirconium bound per kg of support was determined.

  As apparent from the graph shown in FIG. 2, the change in the amount of zirconium bound to the carrier is in a Langmuir type, and as a result, the saturated amount of zirconium bound to the carrier is 0.70 mol / kg. (Dry carrier).

From the above results, the adsorbent according to the present invention is a zirconium solution (pH 2.0 to pH 6.0) in which zirconium is dissolved in water so as to be slightly more than 0.70 mol per kg of the dry carrier prepared as described above. The required amount of the dry carrier can be suspended in and stirred at room temperature for about a day and night.
As a result, zirconium having a saturated bond amount can be bound to the support.

  In the adsorbent according to the present invention, it is not limited to the case where zirconium having a saturated bond amount is bonded to the support as described above, and it may be said that a smaller amount of zirconium than the saturated bond amount may be bonded to the support. Not too long.

(Phosphorus removal method)
Next, a method for removing phosphorus from a liquid to be removed such as domestic wastewater or livestock excreta will be described.
First, the adsorption characteristics of phosphorus at various pH values of the adsorbent according to the present invention were examined.
In addition, although each test result mentioned later shows about the case where the support | carrier prepared from the tangerine juice residue is used, also when using the support | carrier prepared from apple juice residue and pectic acid, a test result substantially the same is obtained.

FIG. 3 is a graph showing the relationship between the adsorption rate of phosphate ions and the pH of the adsorbent according to the present invention, in which the vertical axis indicates the adsorption rate and the horizontal axis indicates the pH.
Phosphoric acid was dissolved in pure water in an appropriate amount, adjusted to various pHs of about pH 1.5 to pH 13.5, and then quantified to prepare a test solution having an initial concentration of phosphate ions of 25 mg / l.

  As described above, each adsorbent having approximately saturated binding amount of zirconium bound to 15 ml of each test solution was dispensed to 25 mg as a dry carrier, and shaken at 30 ° C. for 24 hours. The concentration of phosphate ions collected was measured using an ICP atomic emission spectrometer (ICPS500 type Shimadzu Corporation), and the adsorbent was determined based on the phosphate ion amount decreased from the initial concentration of each test solution. The adsorption rate of phosphate ions on the surface was determined.

As is apparent from the graph shown in FIG. 3, the adsorption rate of phosphate ions to the adsorbent is about 100% in the region of about pH 2.0 to about pH 4.0, exceeding about pH 4.0 and pH 10 About 80% or more in the region of 0.0 or less.
Therefore, the adsorbent according to the present invention can sufficiently adsorb phosphorus in the region of about pH 2.0 or more and about pH 10.0.

Next, removal of phosphorus by a batch method was examined.
FIG. 4 is a graph showing the relationship between the concentration of phosphorus and the binding rate of phosphorus to the adsorbent when phosphorus is removed by the batch method. In the figure, the vertical axis is adsorbed by the adsorbent per 1 g of dry carrier. The mass (mg) of phosphorous is shown, and the horizontal axis shows the shaking time.

  An appropriate amount of phosphoric acid is dissolved in pure water, and the pH is adjusted to 3.0 by adding a small amount of sodium hydroxide. Then, the initial concentration of phosphorus is 20 ppm (circle mark in the figure), 100 ppm (in the figure) △ marks) and 260 ppm (□ marks in the figure) were prepared.

  The adsorbent prepared as described above was dispensed into 15 ml of each test solution to 25 mg as a dry carrier, and the supernatant was collected at appropriate intervals while shaking over time at 30 ° C. The concentration of remaining phosphorus was measured using an emission spectroscopic analyzer (ICPS500 type Shimadzu Corporation), and the amount of phosphorus adsorbed on the adsorbent was determined based on the amount of phosphorus decreased from the initial concentration of each test solution.

As is apparent from the respective graphs shown in FIG. 4, the equilibrium was reached in about 10 hours in any test solution having any phosphoric acid concentration.
Therefore, when phosphorus is removed from the liquid to be removed by a batch method, a stirring operation may be performed for 10 hours or more after an appropriate amount of adsorbent is added to the liquid to be removed.
In addition, when the temperature of the liquid to be removed is low in winter or the like, for example, the stirring operation may be performed for about one day and night.

Next, removal of phosphorus by the column method was examined.
FIG. 5 is a graph showing the results of adsorbing phosphoric acid on the adsorbent by the column method, in which the vertical axis represents the relative value of the concentration of phosphorus at the outlet of the column with respect to the initial concentration of phosphorus in the test solution (column The concentration of the liquid discharged from the column is indicated by the number of beds of the column (1 bed = the volume of the adsorbent packed in the column).

An appropriate amount of phosphoric acid was dissolved in pure water and adjusted to pH 3.0 to obtain a test solution having an initial concentration of phosphorus of 20 mg / l.
The test solution is introduced at a flow rate of 5.02 ml / h into a glass column packed with the adsorbent prepared as described above so as to have a dry carrier mass of 150 mg. Each 02 ml was collected, and the concentration of phosphorus contained in each of the separated liquids was measured using an ICP atomic emission spectrometer (ICPS500 type Shimadzu Corporation), and the column concentration relative to the initial concentration of phosphorus in the test solution was measured. The relative value of the phosphorus concentration at the outlet was determined.

As apparent from the graph shown in FIG. 5, phosphorus was not detected in the liquid flowing out from the column until the number of beds reached 300.
Therefore, in the case of such a column method, if the liquid to be removed contains about 20 mg / l of phosphorus, the liquid to be removed can be processed with a capacity of at least 300 times the volume of the adsorbent packed in the column. .

Next, the type and concentration of the eluent that elutes phosphorus from the adsorbent were studied.
FIG. 6 is a graph showing the relationship between the type and concentration of an eluent that elutes phosphorus from the adsorbent and the elution rate of phosphorus from the adsorbent, and the vertical axis indicates the amount of phosphorus eluted from the adsorbent. The horizontal axis represents the concentration of the eluent.
Phosphorus was adsorbed to the adsorbent prepared as described above until equilibrium was reached.

  On the other hand, sodium hydroxide, hydrochloric acid and sodium chloride (all grades 1 Wako Pure Chemical Industries, Ltd.) are dissolved in appropriate amounts of pure water to obtain sodium hydroxide solutions having various concentrations of 0.2 mol / l to 1.0 mol / l. (Circle mark in the figure), hydrochloric acid solution (triangle mark in the figure), and sodium chloride solution (square mark in the figure) were prepared.

  After 20 mg of the adsorbent adsorbing phosphorus in 15 ml of each co-test solution was dispensed in a wet state and shaken at 30 ° C. for 24 hours, the supernatant was collected, and an ICP atomic emission spectrometer (ICPS500 type Co., Ltd.) was collected. The concentration of phosphate ions eluted was measured using Shimadzu Corporation, and the proportion of the amount of phosphorus eluted was determined based on the amount of phosphorus adsorbed on the adsorbent.

As is clear from FIG. 6, when sodium chloride was used as the eluent, phosphorus could not be eluted from the adsorbent at any concentration.
When hydrochloric acid was used as the eluent, the proportion of phosphorus eluted from the adsorbent was about 40% even at a concentration of 1.0 mol / l.
In contrast, when sodium hydroxide was used as the eluent, phosphorus was eluted from the adsorbent at a concentration of 0.2 mol / l and a ratio of 95% or more.

  At this time, for the sodium hydroxide solution after shaking for 24 hours, an attempt was made to measure zirconium using the ICP atomic emission spectrometer, but zirconium could not be detected.

  On the other hand, since the elution operation of phosphorus can be performed with a sodium hydroxide solution having a relatively low concentration of 0.2 mol / l, the elution operation can be performed safely. Furthermore, waste liquid discharged by the elution operation can be handled safely, and the environmental load of the waste liquid is small, and waste liquid treatment such as neutralization can be easily performed.

Next, it was examined whether 0.2 mol / l sodium hydroxide solution is effective for elution of phosphorus from the adsorbent adsorbed by the column method.
FIG. 7 is a graph showing the results of elution of phosphorus from a column on which phosphorus was adsorbed using a 0.2 mol / l sodium hydroxide solution. In the figure, the vertical axis represents the initial phosphorus in the test solution. The relative value of the concentration of phosphorus at the outlet of the column with respect to the concentration (the concentration of phosphorus at the outlet of the column / the initial concentration of phosphorus), and the horizontal axis indicates the volume of liquid discharged from the column as the number of beds of the column.

  The column described in FIG. 5 was used. The eluent solution is supplied to this column at a flow rate of 5.02 ml / h, and the liquid flowing out from the column is fractionated in increments of 5.02 ml, and the concentration of phosphorus contained in the obtained liquid of each fraction is determined by ICP. Measurement was performed using an atomic emission spectrometer (ICPS500 type Shimadzu Corporation), and the relative value of the concentration of phosphorus at the outlet of the column with respect to the initial concentration of phosphorus in the test solution described in FIG. 5 was determined.

As is apparent from the graph shown in FIG. 7, a very sharp mountain-shaped elution curve was obtained, and the 0.2 mol / l sodium hydroxide solution was also effective in the column method.
The concentration of phosphorus in the eluent with respect to the initial concentration of phosphorus in the test solution was 45 times, and the recovery rate of phosphorus adsorbed on the adsorbent was 95% or more.
At this time, zirconium was not detected in any fraction of the liquid.

(Method of removing phosphorus by batch method)
From the above results, phosphorus is removed from the liquid to be removed by the batch method as follows.
That is, while determining the volume of the liquid to be removed, the concentration of phosphorus contained in the liquid to be removed is determined by a measured value or an estimated value, and based on the results, the amount of adsorbent prepared as described above is determined. Ask. The obtained addition amount of the adsorbent is put into the liquid to be removed and stirred for 10 hours or more to adsorb phosphorus (phosphoric acid) in the liquid to be removed to the adsorbent.

  At this time, the adsorbent can sufficiently adsorb phosphorus in a wide pH range from pH 2.0 to pH 10.0 as described above, while the pH of the liquid to be removed such as domestic wastewater or livestock excreta is almost the same. In this case, the phosphorus adsorption operation can be performed without adjusting the pH because it is within the above pH range.

By recovering the adsorbent adsorbing phosphorus in this way by solid-liquid separation by filtration or subsidence, phosphorus is removed from the liquid to be removed.
The collected adsorbent is put into a sodium hydroxide solution of about 0.2 mol / l (for example, 0.15 to 0.25 mol / l), and stirred for about a day and night, so that the adsorbed phosphorus is dissolved in the sodium hydroxide solution. After eluting into, recover as before. The adsorbent is washed with water at least once to prepare for reuse.

(Method of removing phosphorus by column method)
When removing phosphorus by the column method, it is carried out as follows.
That is, an appropriate amount of adsorbent is packed in a pressure resistant column. The concentration of phosphorus contained in the liquid to be removed is determined in the same manner as before, and the flow rate of the liquid to be removed is determined based on the determined concentration of phosphorus and the capacity of the adsorbent filled. Then, the liquid to be removed is passed through the column until the obtained flow rate is reached, and the phosphorus in the liquid to be removed is adsorbed by the adsorbent in the column to remove phosphorus from the liquid to be removed.

  When the flow of the liquid to be removed through the column is completed, a sodium hydroxide solution of about 0.2 mol / l (for example, 0.15 to 0.25 mol / l) is passed through the column to adsorb the adsorbent in the column. After the phosphorus is eluted, the adsorbent is washed by passing water further and the sodium hydroxide solution is removed to prepare for reuse.

Next, the results of the comparative test will be described.
FIG. 8 is a graph showing the results of measuring the adsorption rate of phosphorus at various pH values for the adsorbent according to the present invention and the adsorbent of the comparative example. In the figure, the circles indicate the adsorbent according to the present invention. In each case, Δ indicates the case where the adsorbent of the comparative example is used. The vertical axis indicates the adsorption rate, and the horizontal axis indicates the pH.

As an adsorbent of the comparative example, a zirconium ferrite-based adsorbent (Seventor (registered trademark) P (Takeda Pharmaceutical Co., Ltd.)) was used.
The test method is the same as the method described in FIG.

As is clear from the graph shown in FIG. 8, in the adsorbent of the comparative example, the adsorption rate of phosphorus is about 90% at pH 2.0, but gradually decreases from pH 2.5 to pH 4.0. It was about 50% at ˜pH 7.0, and further decreased when the pH exceeded 7.0.
On the other hand, in the adsorbent according to the present invention, it is about 100% in the region of about pH 2.0 to about pH 4.0, and about 80 in the region of about pH 4.0 and below pH 10.0. % Or more.

Next, the results of comparing the phosphorus adsorption amounts will be described.
FIG. 9 is a graph showing the results of measuring the adsorption amount of phosphate ions for the adsorbent according to the present invention and the adsorbent of the comparative example, and in the figure, the circles indicate the case where the adsorbent according to the present invention is used. , Δ indicates the case where the comparative adsorbent was used. The vertical axis represents the phosphate ion adsorption amount, and the horizontal axis represents the remaining phosphate ion concentration.

  In the adsorbent according to the present invention, 25 mg each as a dry carrier is added to 15 ml of a phosphoric acid solution (pH 3.0) prepared to have various concentrations from 5 mg / l to 900 mg / l, and 50 mg in the adsorbent according to the comparative example. After each addition and shaking at 30 ° C. for 24 hours, the supernatant was collected, and the concentration of remaining zirconium was measured using an ICP atomic emission spectrometer (ICPS500 type Shimadzu Corporation). Based on the amount of phosphoric acid decreased from the initial concentration of the solution, the amount of phosphoric acid bound per gram of dried product was determined.

  As is apparent from the graph shown in FIG. 9, both graphs are in Langmuir type, and the adsorption amount of the adsorbent according to the present invention is approximately five times the adsorption amount of the adsorbent according to the comparative example. there were.

It is a graph which shows the influence of pH at the time of making a zirconium ion couple | bond with the support | carrier which concerns on this invention. It is a graph which shows the relationship between a zirconium concentration and the binding amount of the zirconium ion to the support | carrier which concerns on this invention. It is a graph which shows the relationship between the adsorption rate of phosphorus of adsorbent which concerns on this invention, and pH. It is a graph which shows the relationship between the density | concentration of phosphorus in the case of removing phosphorus by a batch method, and the binding rate of phosphorus to an adsorbent. It is a graph which shows the result of having adsorbed phosphate ion to an adsorbent by the column method. It is a graph which shows the relationship between the kind and the density | concentration of the eluent which elute phosphorus from adsorbent, and the elution rate of phosphorus from adsorbent. It is a graph which shows the result of having eluted phosphate ion from the column which adsorb | sucked the phosphate ion using 0.2 mol / l sodium hydroxide solution. It is a graph which shows the result of having measured the adsorption rate of phosphorus in various pH about the adsorbent which concerns on this invention, and the adsorbent of a comparative example. It is a graph which shows the result of having measured the adsorption amount of the phosphate ion about the adsorbent which concerns on this invention, and the adsorbent of a comparative example.

Claims (4)

In an adsorbent that is formed by appropriately binding a metal to a carrier and adsorbs phosphorus contained in the liquid to be removed.
An adsorbent obtained by binding zirconium to a carrier containing pectic acid as a main component.   The adsorbent according to claim 1, wherein the carrier is prepared by using mandarin juice residue or apple juice residue as a raw material. In a method of removing phosphorus from the liquid to be removed by adsorbing phosphorus in the liquid to be removed to the adsorbent,
A method for removing phosphorus, comprising using the adsorbent according to claim 1.   The method for removing phosphorus according to claim 3, wherein the adsorbent adsorbing phosphorus is treated with a sodium hydroxide solution having an appropriate concentration to elute phosphorus from the adsorbent.

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