Method of Removing Organic Pollutants in Water by Zero-Valent Iron Enhanced Hypochlorite

Abstract

A method of removing organic pollutants in water by zero-valent iron enhanced hypochlorite includes the steps of: adjusting a pH of raw water containing organic pollutants to 4.0˜9.0; adding zero-valent iron solid and hypochlorite to the raw water in a mixer; and turning on the mixer to carry out stirring reaction. The method constructs a Fenton-like system through the redox reaction in the heterogeneous micro-interface region that occurs between zero-valent iron and hypochlorite which produces a variety of active oxidizing species with high occurrence, improves the shortcomings of the traditional Fenton method, broadens the applicable range of pH, and increases the removal efficiency of pollutants in water by 35˜95%.

Claims

1. A method of removing organic pollutants in water by zero-valent iron enhanced hypochlorite, comprising the steps of: (a) weighing zero-valent iron in solid form; (b) preparing a mother liquor of hypochlorite; (c) adjusting a pH of raw water containing organic pollutants to 4.0˜9.0; (d) adding the zero-valent iron solid and the mother liquor of hypochlorite to the raw water containing organic pollutants in a mixer, where a final concentration of hypochlorite in the mixer is 0.02˜5 mmol/L; and (e) turning on the mixer to carry out stirring reaction to remove the organic pollutants in the raw water.

2. The method according to claim 1, characterized in that, the zero-valent iron in step (a) is selected from the group consisting of ordinary zero-valent iron, phosphorylated zero valent iron and borated zero valent iron.

3. The method according to claim 1, wherein a particle size of the zero-valent iron in step (a) is 10 nm˜50 μm.

4. The method according to claim 1, wherein a concentration of the mother liquor of hypochlorite in step (b) is 0.1˜2.5 mol/L.

5. The method according to claim 1, wherein the hypochlorite in step (b) is selected from one or more of the group consisting of: sodium hypochlorite, calcium hypochlorite and magnesium hypochlorite.

6. The method according to claim 1, wherein the organic pollutants in the raw water in step (c) is one or more of benzoic acid, atrazine, carbamazepine and nitrobenzene.

7. The method according to claim 1, wherein the pH of raw water containing organic pollutants in step (c) is adjusted to 4.0-7.0.

8. The method according to claim 1, wherein a molar ratio of the zero-valent iron in solid form to the hypochlorite in step (d) is 2-20.

9. The method according to claim 1, wherein a rotation speed of the mixer in step (e) is 100-200 r/min.

10. The method according to claim 1, wherein a reaction time of the stirring reaction in step (e) is 10 min-60 min.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 is a flowchart of a method for removing organic pollutants in water by zero-valent iron enhanced hypochlorite according to a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0021] Embodiment 1: The method for zero-valent iron enhanced hypochlorite to remove organic pollutants in water according to this embodiment of the present invention comprises the following steps:

[0022] (a) weighing zero-valent iron in solid form;

[0023] (b) preparing a mother liquor of hypochlorite;

[0024] (c) adjusting a pH of raw water containing organic pollutants to 4.0˜9.0;

[0025] (d) adding the zero-valent iron solid and the mother liquor of hypochlorite to the raw water containing organic pollutants in a mixer, where a final concentration of hypochlorite in the mixer is 0.02˜5 mmol/L; and

[0026] (e) turning on the mixer to carry out stirring reaction to remove the organic pollutants in the raw water.

[0027] Embodiment 2: The difference between this embodiment and the Embodiment 1 is that: the zero-valent iron in step (a) is selected from the group consisting of ordinary zero valent iron, phosphorylated (modified) zero valent iron and borated (modified) zero valent iron.

[0028] Embodiment 3: The difference between this embodiment and the Embodiment 1 or the Embodiment 2 is that: a particle size of the zero-valent iron in step (a) is 10 nm˜50 μm.

[0029] Embodiment 4: The difference between this embodiment and one of the Embodiments 1-3 is that: a concentration of the mother liquor of hypochlorite in step (b) is 0.1˜2.5 mol/L.

[0030] Embodiment 5: The difference between this embodiment and one of the Embodiments 1-4 is that: the hypochlorite in step (b) is selected from one or more of the group consisting of: sodium hypochlorite, calcium hypochlorite and magnesium hypochlorite.

[0031] Embodiment 6: The difference between this embodiment and one of the Embodiments 1-5 is that: the organic pollutants in the raw water in step (c) is one or more of benzoic acid (BA), atrazine (ATZ), carbamazepine (CBZ), and nitrobenzene (NB).

[0032] Embodiment 7: The difference between this embodiment and one of the Embodiments 1-6 is that: the pH of raw water containing organic pollutants in step (c) is adjusted to 4.0˜7.0.

[0033] Embodiment 8: The difference between this embodiment and one of the Embodiments 1-7 is that: a molar ratio of the zero-valent iron solid to the hypochlorite in step (d) is 2-20.

[0034] Embodiment 9: The difference between this embodiment and one of the Embodiments 1-8 is that: a rotation speed of the mixer in step (e) is 100˜200 r/min.

[0035] Embodiment 10: The difference between this embodiment and one of the Embodiments 1-8 is that: a reaction time of the stirring reaction in step (e) is 10 min˜60 min.

[0036] Example 1: According to this example, the method of zero-valent iron enhanced hypochlorite to remove organic pollutants in water comprises the steps of:

[0037] (a) weighing 10 mg of zero-valent iron in solid form;

[0038] (b) preparing a mother liquor of sodium hypochlorite having a concentration of 100 mmol/L;

[0039] (c) adjusting a pH of raw water containing BA to 4.0, where the concentration of BA in the raw water is 10 μmol/L;

[0040] (d) adding the 10 mg of zero-valent iron in solid form and the mother liquor of sodium hypochlorite to 1 L of the raw water in a mixer, where a final concentration of sodium hypochlorite in the mixer (the concentration of sodium hypochlorite in the raw water after adding the mother liquor of sodium hypochlorite) is 50˜60 μmol/L; and

[0041] (e) turning on the mixer to carry out stirring reaction at a speed of 200 r/min for 15 minutes to remove the organic pollutants in the raw water.

[0042] In this example, the comparative examples are adding zero-valent iron alone and sodium hypochlorite alone. The removal rate of BA in this example is 88%, compared to the removal rate of 3% by adding sodium hypochlorite alone and the removal rate of 40% by using zero-valent iron alone. In other words, the removal rate is increased from 3% and 40% to 88%.

[0043] Example 2: According to this example, the method of zero-valent iron enhanced hypochlorite to remove organic pollutants in water comprises the steps of:

[0044] (a) weighing 20 mg of zero-valent iron in solid form;

[0045] (b) preparing a mother liquor of sodium hypochlorite having a concentration of 100 mmol/L;

[0046] (c) adjusting a pH of raw water containing ATZ to 4.5, where the concentration of ATZ in the raw water is 3 μmol/L;

[0047] (d) adding the weighed 20 mg of zero-valent iron in solid form and the mother liquor of sodium hypochlorite to 1 L of the raw water in a mixer, where a final concentration of sodium hypochlorite in the mixer is 100˜200 μmol/L; and

[0048] (e) turning on the mixer to carry out stirring reaction at a speed of 200 r/min for 30 minutes to remove the organic pollutants in the raw water.

[0049] In this example, the comparative examples are adding zero-valent iron alone and adding sodium hypochlorite alone. The removal rate of ATZ in this example is 92%, compared to the removal rate of 10% by adding sodium hypochlorite alone and the removal rate of 5% by using zero-valent iron alone. In other words, the removal rate is increased from 10% and 5% to 92%.

[0050] Example 3: According to this example, the method of zero-valent iron enhanced hypochlorite to remove organic pollutants in water comprises the steps of:

[0051] (a) weighing 50 mg of zero-valent iron in solid form;

[0052] (b) preparing a mother liquor of sodium hypochlorite having a concentration of 500 mmol/L;

[0053] (c) adjusting a pH of raw water containing NB to 4.0, where the concentration of ATZ in the raw water is 5 μmol/L;

[0054] (d) adding the weighed 50 mg of zero-valent iron in solid form and the mother liquor of sodium hypochlorite to 1 L of the raw water in a mixer, where a final concentration of sodium hypochlorite in the mixer is 70˜80 μmol/L; and

[0055] (e) turning on the mixer to carry out stirring reaction at a speed of 200 r/min for 60 minutes to remove the organic pollutants in the raw water.

[0056] In this example, the comparative examples are adding zero-valent iron alone and adding sodium hypochlorite alone. The removal rate of NB in this example is 89%, compared to the removal rate of 12% by adding sodium hypochlorite alone and the removal rate of 24% by using zero-valent iron alone. In other words, the removal rate is increased from 12% and 24% to 89%.

[0057] Example 4: According to this example, the method of zero-valent iron enhanced hypochlorite to remove organic pollutants in water comprises the steps of:

[0058] (a) weighing 5 mg of zero-valent iron in solid form;

[0059] (b) preparing a mother liquor of calcium hypochlorite having a concentration of 100 mmol/L;

[0060] (c) adjusting a pH of raw water containing CBZ to 4.0, where the concentration of CBZ in the raw water is 5 μmol/L;

[0061] (d) adding the weighed 5 mg of zero-valent iron in solid form and the mother liquor of calcium hypochlorite to 1 L of the raw water in a mixer, where a final concentration of calcium hypochlorite in the mixer is 20˜30 μmol/L; and

[0062] (e) turning on the mixer to carry out stirring reaction at a speed of 200 r/min for 20 minutes to remove the organic pollutants in the raw water.

[0063] In this example, the comparative examples are adding zero-valent iron alone and adding calcium hypochlorite alone. The removal rate of CBZ in this example is 93%, compared to the removal rate of 23% by adding calcium hypochlorite alone and the removal rate of 5% by using zero-valent iron alone. In other words, the removal rate is increased from 23% and 5% to 93%.

[0064] Example 5: According to this example, the method of zero-valent iron enhanced hypochlorite to remove organic pollutants in water comprises the steps of:

[0065] (a) weighing 30 mg of zero-valent iron in solid form;

[0066] (b) preparing a mother liquor of sodium hypochlorite having a concentration of 200 mmol/L;

[0067] (c) adjusting a pH of raw water containing SMX to 4.5, where the concentration of SMX in the raw water is 5 μmol/L;

[0068] (d) adding the weighted 30 mg of zero-valent iron in solid form and the mother liquor of sodium hypochlorite to 1 L of the raw water in a mixer, where a final concentration of sodium hypochlorite in the mixer is 30˜40 μmol/L; and

[0069] (e) turning on the mixer to carry out stirring reaction at a speed of 200 r/min for 45 minutes to remove the organic pollutants in the raw water.

[0070] In this example, the comparative examples are adding zero-valent iron alone and sodium hypochlorite alone. The removal rate of SMX in this example is 93%, compared to the removal rate of 10% by adding sodium hypochlorite alone and the removal rate of 5% by using zero-valent iron alone. In other words, the removal rate is increased from 10% and 5% to 93%.

[0071] Example 6: According to this example, the method of zero-valent iron enhanced hypochlorite to remove organic pollutants in water comprises the steps of:

[0072] (a) weighing 80 mg of zero-valent iron in solid form;

[0073] (b) preparing a mother liquor of calcium hypochlorite having a concentration of 300 mmol/L;

[0074] (c) adjusting a pH of raw water containing phenol to 5.0, where the concentration of phenol in the raw water is 10 μmol/L;

[0075] (d) adding the weighed 80 mg of zero-valent iron in solid form and the mother liquor of calcium hypochlorite to 1 L of the raw water in a mixer, where a final concentration of calcium hypochlorite in the mixer is 35˜50 μmol/L; and

[0076] (e) turning on the mixer to carry out stirring reaction at a speed of 200 r/min for 20 minutes to remove the organic pollutants in the raw water.

[0077] In this example, the comparative examples are adding zero-valent iron alone and adding calcium hypochlorite alone. The removal rate of phenol in this example is 95%, compared to the removal rate of 30% by adding calcium hypochlorite alone and the removal rate of 5% by using zero-valent iron alone. In other words, the removal rate is increased from 30% and 5% to 95%.

[0078] One skilled in the art will understand that the embodiment of the present invention as shown in the drawings and described above is exemplary only and not intended to be limiting.

[0079] It will thus be seen that the objects of the present invention have been fully and effectively accomplished. Its embodiments have been shown and described for the purposes of illustrating the functional and structural principles of the present invention and is subject to change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.