Preparation method and application for a resin-based iron oxide-containing composite phosphate removal adsorbent

Abstract

A preparation method of a resin-based iron oxide-containing composite phosphate removal adsorbent is provided. An alkaline anion resin is taken as a base, a potassium ferrate is used as an iron source, and a characteristics of ferrate ions easily adsorbed on a surface of the anion resin are utilized to prepare resin-based iron oxide-containing composite phosphate removal adsorbent by one-step in-situ hydrolysis precipitation, compared with the related art, a preparation process of the disclosure is relatively simpler, a time period is shorter, and a production cost is lower. It has a strong ability to eliminate interference from other anions in the waste effluents, and it has a strong adsorption capacity, fast adsorption speed and large adsorption capacity for the phosphate. Moreover, it has the advantages of strong regeneration ability and multiple repeated use times.

Claims

1. A preparation method of a resin-based iron oxide-containing composite phosphate removal adsorbent, comprising: step (i) adding an alkaline anion resin into a prepared alkaline potassium ferrate solution, and stirring for 1-5 hours at room temperature to make ferrate ions exchange with anions of the alkaline anion resin; step (ii) discarding a supernatant in the solution obtained in step (i), adding water, heating to 50° C.-70° C. and stirring again for 1-3 hours to make the ferrate ions exchanged onto the alkaline anion resin hydrolyze into a ferric hydroxide; step (iii) adding a 2-10% by mass sodium chloride solution to the solution obtained in step (ii) to transform a hydroxyl group bonded onto the alkaline anion resin into Cl.sup.− to thereby obtain a composite resin loaded with nano-sized hydrated iron oxides; and step (iv) washing the composite resin loaded with nano-sized hydrated iron oxides to be neutral and then drying to obtain the resin-based iron oxide-containing composite phosphate removal adsorbent; wherein the potassium ferrate solution of step (i) has a concentration of 0.03-0.2 mol/L, and a pH of 9-12; wherein the concentration of the added alkaline anion resin is 20-200 g/L.

2. A method of treating phosphate-containing waste effluents, comprising the following steps: packing the resin-based iron oxide-containing composite phosphate removal adsorbent obtained by the preparation method as claimed in claim 1 into a column, and introducing phosphate-containing waste effluents into the column for elution at a temperature of 20-40° C. and a flow rate of 10-30BV/h; and adding a mixed solution of 2-5% NaCl and 2-5% NaOH for restoring the alkaline anion resin, after the elution is completed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a three-dimensional schematic diagram of an ecological ditch of a seventh embodiment.

(2) In the FIG. 1, 1—water plant Zizania, 2—gravel, 3—first water intake point, 4—100 mesh nylon net bag wrapped with the resin-based iron oxide-containing composite phosphate removal adsorbent, 5—fixed iron frame, 6—second water intake point, and 7—overflow weir.

DETAILED DESCRIPTION OF EMBODIMENTS

(3) The disclosure is further illustrated by specific embodiments below.

First Embodiment

(4) A potassium ferrate of 7.14 g was dissolved in a water of 400 ml with pH=10 to prepare an alkaline potassium ferrate solution with concentration of 0.09 mol/L, an IRA-402 resin of 20 g was immediately added into the alkaline potassium ferrate solution, and magnetically stirred for 2 h to make ferrate ions exchange with anions of the IRA-402 resin, and then, a supernatant was discarded and a water of 200 ml was added, and stirred at 50° C. for 1 hour to make the ferrate ions exchanged onto the resin hydrolyze into a ferric hydroxide, after that, a hydroxyl group bonded onto the resin was transformed into Cl.sup.− with 5% by mass sodium chloride solution to thereby obtain a composite resin loaded with nano-sized hydrated iron oxides, and finally the composite resin loaded with nano-scale hydrated iron oxides was washed to be neutrality, and dried or air dried in a cool place to obtain a resin-based iron oxide-containing composite phosphate removal adsorbent with a solid loading of Fe(III) being 25.7 mg/g.

Second Embodiment

(5) A potassium ferrate of 13.85 g was dissolved in a water of 1000 ml with pH=12 to prepare an alkaline potassium ferrate solution with concentration of 0.07 mol/L, an IRA-900 resin of 100 g was immediately added into the alkaline potassium ferrate solution, and mechanical stirred for 2 h to make ferrate ions exchange with anions of the IRA-900 resin. And then, a supernatant was discarded and a water of 500 ml was added, and stirred at 70° C. for 1 hour to make the ferrate ions exchanged onto the resin hydrolyze into a ferric hydroxide, after that, a hydroxyl group bonded onto the resin was transformed into Cl.sup.− with 2% by mass sodium chloride solution to thereby obtain a composite resin loaded with nano-sized hydrated iron oxides, and finally the composite resin loaded with nano-scale hydrated iron oxides was washed to be neutrality, and dried or air dried in a cool place to obtain a resin-based iron oxide-containing composite phosphate removal adsorbent with a solid loading of Fe(III) being 24.5 mg/g.

Third Embodiment

(6) A potassium ferrate of 5.94 g was dissolved in a water of 200 ml with pH=9 to prepare an alkaline potassium ferrate solution with concentration of 0.15 mol/L, a D-201 resin of 40 g was immediately added into the alkaline potassium ferrate solution, and magnetically stirred for 3 h to make ferrate ions exchange with anions of the D-201 resin, and then, a supernatant was discarded and a water of 100 ml was added, and stirred at 60° C. for 2 hour to make the ferrate ions exchanged onto the resin hydrolyze into a ferric hydroxide, after that, a hydroxyl group bonded onto the resin was transformed into Cl.sup.− with 8% by mass sodium chloride solution to thereby obtain a composite resin loaded with nano-sized hydrated iron oxides, and finally the composite resin loaded with nano-scale hydrated iron oxides was washed to be neutrality, and dried or air dried in a cool place to obtain a resin-based iron oxide-containing composite phosphate removal adsorbent with a solid loading of Fe(III) being 39.2 mg/g.

Fourth Embodiment

(7) The resin-based iron oxide-containing composite phosphate removal adsorbent (0.5 g/L) prepared in first embodiment, the resin-based iron oxide-containing composite phosphate removal adsorbent (0.5 g/L) prepared in second embodiment and the resin-based iron oxide-containing composite phosphate removal adsorbent (0.5 g/L) prepared in third embodiment were respectively added into phosphate solutions (0.1 mM P—PO.sub.4.sup.3−) of 100 mL with different sulfate concentrations (0-15 mM) for adsorption experiments. Solutions of the adsorption experiments have an initial pH of 7 (no adjustment in the adsorption process), constant temperature vibration adsorption for 24 hours, detection of remaining phosphate contents in suspensions, calculation of phosphate removal rates, and comparison with original resins, results are shown in Table 1.

(8) Table 1 shows the phosphate removal rates (%) measured at different sulfate radical concentrations

(9) TABLE-US-00001 SO.sub.4.sup.2−(mM) 0 0.15 0.3 0.6 1 3 5 10 15 First 99 99 97 69 42 30 28 26 25 embodiment Second 93 90 78 54 32 21 19 18 18 embodiment Third 96 92 84 44 26 24 22 19 17 Embodiment IRA-402 90 76 69 19 6 5 1 0 0 IRA-900 85 68 30 15 2 0 0 0 0 D-201 88 73 42 24 10 4 0 0 0

(10) It can be seen from the above results that as the sulfate concentration increases, the phosphate removal rate of the resin decreases, but the phosphate removal rate of the resin-based iron oxide-containing composite phosphate removal adsorbent is significantly higher than that of the untreated resin. Especially in first embodiment, until the sulfate radical concentration reached 0.3 mM, the phosphate removal rate did not significantly decrease, so the adsorption selectivity to phosphate is the highest and the anti-interference ability is the strongest.

Fifth Embodiment

(11) The resin-based iron oxide-containing composite phosphate removal adsorbent prepared in first embodiment, the resin-based iron oxide-containing composite phosphate removal adsorbent prepared in second embodiment and the resin-based iron oxide-containing composite phosphate removal adsorbent prepared in third embodiment were respectively added into solutions with an initial pH of 7 and a phosphate concentration of 10 mg/L, an amount of adding the resin-based iron oxide-containing composite phosphate removal adsorbent is 0.5 g/L, and then samples are taken at different time points of 10, 20, 30, 45, 60, 80, 100, 120 min to detect remaining phosphate contents in suspensions, calculation of phosphate removal rates, and comparison with original resins, results are shown in Table 2.

(12) Table 2 shows the phosphate removal rates (%) measured at different time points

(13) TABLE-US-00002 Time(min) 10 20 30 45 60 80 100 120 First 10 19 26 39 45 54 62 69 embodiment Second 9 21 30 39 51 64 69 73 embodiment Third 11 24 29 41 52 63 67 72 embodiment IRA-402 5 13 22 31 38 47 52 56 IRA-900 5 14 20 25 33 41 45 52 D-201 7 11 18 26 33 42 46 54

(14) It can be seen from the above result that as time goes on, the phosphate removal rates of the resin increases correspondingly, but the phosphate removal rates of the resin-based iron oxide-containing composite phosphate removal adsorbents are significantly higher than that of the untreated resins. Therefore, an adsorption capacity of the resin-based iron oxide-containing composite phosphate removal adsorbent of the disclosure is stronger and faster.

Sixth Embodiment

(15) The resin-based iron oxide-containing composite phosphate removal adsorbent of 5 mL prepared in first embodiment, the resin-based iron oxide-containing composite phosphate removal adsorbent of 5 mL prepared in second embodiment, and the resin-based iron oxide-containing composite phosphate removal adsorbent of 5 mL prepared in third embodiment were respectively added into plexiglass adsorption columns with an inner diameter of 12 mm and a length of 25 mm, and then a phosphate-containing waste effluents (P=2 mg/L, and SO.sub.4.sup.2−=120 mg/L, Cl.sup.−═HCO.sub.3.sup.−=100 mg/L, NO.sub.3.sup.−=40 mg/L, pH=7) flowed through the adsorption column from top to bottom for elution at a temperature of 30° C. and a flow rate of 15 BV/h (Bed Volume per hour), treatment volumes of effluent P concentrations controlled below 0.5 mg/L in the three embodiments are shown in Table 3. After the adsorption is broken through (also referred to the elution is completed), use 50 mL of a mixed solution of 4% mass percentage NaCl and 4% mass percentage NaOH to pass through the adsorption column at a temperature of 20° C. and a flow rate of 10 mL/h to regenerate (also referred to as restore) the alkaline anion resin. Restoring rates are shown in Table 3, and restored alkaline anion resins were rinsed with water to be neutral can continue to be used.

(16) TABLE-US-00003 TABLE 3 Waste effluents treatment Resin restoring volume rate First embodiment 630BV 98% Second embodiment 650BV 98% Third embodiment 550BV 97% IRA-402 350BV 99% IRA-900 360BV 99% D-201 310BV 99%

(17) It can be seen from the above results that the amount of phosphate-containing waste effluents treated by the resin-based iron oxide-containing composite phosphate removal adsorbent is much higher than that of the untreated resin, and the resin-based iron oxide-containing composite phosphate removal adsorbent has strong restoring ability.

Seventh Embodiment

(18) The resin-based iron oxide-containing composite phosphate removal adsorbent prepared in first embodiment was added to a hard ecological ditch, and a specific structure is shown in FIG. 1. After processing farmland runoff from about 6 acres of paddy fields, in the 54 days of continuous monitoring, a second water intake point 6 compared with a first water intake point 3, an average reduction of PO.sub.3.sup.4− in farmland runoff is 34.4%.

(19) The above is detailed description of the disclosure in combination with specific preferred embodiments, and it cannot be assumed that the specific implementations of the disclosure are limited to these descriptions. For the person of ordinary skill in the technical field to which the disclosure belongs, without deviating from the concept of the disclosure, several simple deductions or replacements can be made, which should be regarded as falling within the protection scope of the disclosure.