Method for removing hexavalent chromium in water body

Abstract

The invention provides a method for removing hexavalent chromium in a water body, and belongs to the field of water body purification, and in particular, the method for removing hexavalent chromium in the water body provided by the invention comprises the following steps: adding a water body purifying agent into the water body containing hexavalent chromium, and carrying out oscillation or stirring treatment on the water body under the condition of controlling the pH value of the water body to be 3.5-7, the water body after oscillation or stirring treatment is filtered, hexavalent chromium in the water body is removed, and the water body purifying agent comprises chitosan. According to the method, the hexavalent chromium in the water body can be reduced and adsorbed by using the unmodified chitosan under the condition of controlling the reaction pH value, and the method for removing the hexavalent chromium in the water body is a novel water body purification method which is environment-friendly, low in cost, simple to operate and high in efficiency, and has a wide application prospect.

Description

Technical Field

[0001] The invention relates to the field of water purification, and in particular to a method for removing hexavalent chromium from water. Background Art

[0002] In recent years, with the rapid development of chromium-related industries such as chromium salts, leather, printing and dyeing, and electroplating, the accumulation of a large amount of chromium slag has led to serious soil chromium pollution and further migrated to groundwater. After chromium-containing pollutants enter the environment, they are easily accumulated in groundwater, surface water and soil, and can pose a serious threat to ecosystems and human health through "biomagnification". Hexavalent chromium (Cr(VI)) is easily soluble in water and has strong oxidizing properties. It can cause irreversible oxidative damage after ingestion by animals. Long-term exposure to heavy metal chromium pollution in the human body can cause damage to organs such as the nervous system, liver and kidneys. Since Cr(VI) is difficult to be excreted from the body through general biological metabolic pathways, the heavy metal chromium content will gradually accumulate along the food chain through animal metabolism and ingestion. Cr(VI) has been listed as a carcinogen, and skin contact may cause allergies or hereditary gene defects. Its lasting harm to the environment is also a cause for concern. Therefore, the need to control chromium pollution is becoming increasingly urgent. In contrast, trivalent chromium (Cr(III)) is less toxic, only 1% of Cr(VI), and has lower solubility and mobility. It is a trace element required by the human and animal bodies and is involved in the metabolism of sugars and fats. Therefore, reducing Cr(VI) to Cr(III) is an effective strategy for treating hexavalent chromium pollution. Currently, many studies are devoted to removing Cr(VI) from soil, groundwater and wastewater, but the commonly used physical and chemical reduction methods have limited effects, require a lot of reducing agents, are costly, and are complex to operate. They are also prone to secondary pollution and damage the aquatic ecosystem. Therefore, it is urgent to develop a hexavalent chromium removal method that has strong reducing ability, low cost, and is not prone to secondary pollution. Summary of the invention

[0003] The technical problem to be solved by the present invention is how to remove hexavalent chromium in water at low cost, quickly and efficiently without destroying the water ecosystem.

[0004] In order to solve the above technical problems, the present invention provides a method for removing hexavalent chromium in water, comprising the following steps: adding a water purifier to water containing hexavalent chromium, oscillating or stirring the water while controlling the pH of the water to be 3.5-7, filtering the water after the oscillation or stirring treatment, and completing the removal of hexavalent chromium in the water, wherein the water purifier comprises chitosan.

[0005] In the method for removing hexavalent chromium from water provided by the present invention, a water purifier is used to achieve adsorption and reduction of hexavalent chromium. The water purifier used in the present invention includes chitosan, which shows important application prospects in the field of sewage treatment. However, chitosan alone cannot remove hexavalent chromium from water. The current method of removing hexavalent chromium from sewage using chitosan usually requires modification of chitosan. In the water purifier provided by the present invention, it is only necessary to strictly control the pH of the water while using chitosan to achieve adsorption and reduction of hexavalent chromium by chitosan, without the need to modify chitosan, thereby overcoming the problems of high cost, complex operation, low efficiency, and easy secondary pollution when using chitosan and nanomaterials to remove hexavalent chromium in the prior art.

[0006] Preferably, the concentration of chitosan in the water body after adding the water purifier is 0.1-50 g / L.

[0007] Preferably, the concentration of hexavalent chromium in the water containing hexavalent chromium is greater than or equal to 0.1 mg / mL.

[0008] Preferably, the water purifier further comprises a pH regulator, and the pH regulator is an acid or an acid salt.

[0009] More preferably, the pH adjuster is selected from any one or more of an acid, an ammonium salt, and a dihydrogen phosphate.

[0010] To control the pH of the reaction system, the water purifier provided by the present invention also includes a specific type of pH regulator, which can effectively improve the reduction adsorption capacity and efficiency of chitosan to hexavalent chromium within a specific pH range, and can greatly shorten the reaction time and save time cost. At the same time, the pH regulator used in the present invention is an acid, an acid salt or a buffer salt, wherein the acid salt is selected from any one or more of ammonium salts and dihydrogen phosphates. After the reaction, the sewer network can be discharged through simple treatment, and secondary pollution will not be generated to the water body.

[0011] Preferably, the duration of the oscillation or stirring treatment is 1 min to 168 h.

[0012] Preferably, the rotation speed of oscillation or stirring is 10-300 rpm / min.

[0013] Beneficial effects of the present invention: The present invention provides a method for removing hexavalent chromium from water, that is, applying the water purifier provided by the present invention to hexavalent chromium wastewater, and by controlling the pH of the reaction, the chitosan in the water purifier can achieve the reduction adsorption of hexavalent chromium in the water without being modified, and the process is simple to operate and easy to implement. At the same time, the present invention also adds a specific pH regulator to the water purifier to improve the adsorption and reduction efficiency of hexavalent chromium by chitosan. It can be seen that the method for removing hexavalent chromium from water provided by the present invention is an environmentally friendly, low-cost, simple to operate, and highly efficient new water purification method, which has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a time-hexavalent chromium residual ratio curve diagram of each pH experimental group in Example 1 of the specific implementation mode of the present invention; Figure 2 It is a time-hexavalent chromium residual ratio curve diagram of each control group and experimental group in Example 2 of the specific implementation method of the present invention; Figure 3 It is a time-hexavalent chromium residual ratio curve diagram of each control group and experimental group in Example 3 of the specific implementation method of the present invention; Figure 4 It is a time-hexavalent chromium residual ratio curve diagram of each control group and experimental group in Example 4 of the specific implementation method of the present invention. DETAILED DESCRIPTION

[0015] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only used to illustrate the implementation method and typical parameters of the present invention, and are not used to limit the parameter range described in the present invention. Reasonable changes derived therefrom are still within the scope of protection of the claims of the present invention.

[0016] It should be noted that the endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this article.

[0017] Unless otherwise defined, all terms, symbols and other scientific terms used herein are intended to have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. In some cases, the terms with conventionally understood meanings are defined herein for the purpose of illustrating or facilitating reference, and such definitions herein should not be construed as indicating significant differences from conventional understandings in the art. The technical methods described or cited herein are generally well understood by those skilled in the art and are adopted by conventional methods. Unless otherwise stated, the use of commercially available reagents and instruments is carried out in accordance with the schemes and parameters given by the manufacturer.

[0018] The specific embodiment of the present invention provides a method for removing hexavalent chromium from water. In the method, a water purifier is mainly added to the water containing hexavalent chromium, the water is shaken or stirred while the pH of the water is controlled to be 3.5 to 7, and the water after the shaking or stirring treatment is filtered to complete the removal of hexavalent chromium from the water. In this embodiment, the components of the water purifier include chitosan. As mentioned above, the current method for removing hexavalent chromium from water often has defects such as high cost, complicated operation, and secondary pollution. Although polysaccharides such as chitosan have the ability to adsorb and remove hexavalent chromium to a certain extent, the hexavalent chromium adsorption capacity of unmodified chitosan is low. The specific embodiment of the present invention controls the pH of the reaction system so that chitosan can show extremely strong hexavalent chromium reduction adsorption capacity without modification.

[0019] In the above embodiment, the concentration of chitosan in the water body after adding the water purifier is 0.1~50g / L. The amount of water purifier added to the water body containing hexavalent chromium should be based on the chitosan concentration. The final concentration of chitosan in the water body containing hexavalent chromium is preferably 0.1~50g / mL. If the final concentration of chitosan is too low, it cannot be guaranteed that the hexavalent chromium in the water body is completely adsorbed and reduced. If the chitosan concentration is too high, it will lead to excessive costs and waste of resources.

[0020] In the above embodiment, the concentration of hexavalent chromium in the water containing hexavalent chromium is greater than or equal to 0.1 mg / mL. More preferably, the hexavalent chromium content should be controlled in the range of 10-40 mg / mL. The above water purifier has excellent removal ability for hexavalent chromium in this concentration range.

[0021] In another embodiment, the water purifier used in the above method further includes a pH adjuster, and the pH adjuster is selected from any one or more of an acid, an ammonium salt, and a dihydrogen phosphate.

[0022] In the aforementioned embodiment, the rotation speed of oscillation or stirring is 10-300 rpm / min. Under the condition of controlling the pH of the water body, controlling the oscillation or stirring speed can increase the adsorption reduction rate of hexavalent chromium. If the speed is lower than 10 rpm / min, the hexavalent chromium reduction rate is too slow and may have adverse effects. If the speed is higher than 300 rpm / min, the particle structure of the polysaccharide may be destroyed.

[0023] The technical solution of the present invention is further described below through specific implementation methods.

[0024] Example 1 The water purifier in this embodiment includes chitosan and a pH regulator, and the pH regulator is HCl Chitosan was added to an aqueous solution containing 10 mg / mL hexavalent chromium. The concentration of chitosan in the final mixed solution was 2 g / mL. The mixed solution was placed in a constant temperature oscillator and oscillated at 100 rpm / min for 168 hours at 25°C. The pH of the reaction system was controlled to be 2.0. Samples were taken every 24 hours to detect the hexavalent chromium content in the mixed solution. The results were as follows: Figure 1 As shown in the pH=2.0 curve.

[0025] Chitosan was added to an aqueous solution containing 10 mg / mL hexavalent chromium. The concentration of chitosan in the final mixed solution was 2 g / mL. The mixed solution was placed in a constant temperature oscillator and oscillated at 100 rpm / min at 25°C for 168 hours. The pH of the reaction system was controlled to be 3.5 during the reaction. Samples were taken every 24 hours to detect the hexavalent chromium content in the mixed solution. The results were as follows: Figure 1 As shown in the pH=3.5 curve.

[0026] Chitosan was added to an aqueous solution containing 10 mg / mL hexavalent chromium. The concentration of chitosan in the final mixed solution was 2 g / mL. The mixed solution was placed in a constant temperature oscillator and oscillated at 100 rpm / min at 25°C for 168 hours. The pH of the reaction system was controlled to be 4.5 during the reaction. Samples were taken every 24 hours to detect the hexavalent chromium content in the mixed solution. The results were as follows: Figure 1 As shown in the pH=4.5 curve.

[0027] Chitosan was added to an aqueous solution containing 10 mg / mL hexavalent chromium. The concentration of chitosan in the final mixed solution was 2 g / mL. The mixed solution was placed in a constant temperature oscillator and oscillated at 100 rpm / min for 168 hours at 25°C. The pH of the reaction system was controlled to be 5.5 during the reaction. Samples were taken every 24 hours to detect the hexavalent chromium content in the mixed solution. The results were as follows: Figure 1 As shown in the pH=5.5 curve.

[0028] Chitosan was added to an aqueous solution containing 10 mg / mL hexavalent chromium. The concentration of chitosan in the final mixed solution was 2 g / mL. The mixed solution was placed in a constant temperature oscillator and oscillated at 100 rpm / min at 25°C for 168 hours. The pH of the reaction system was controlled to be 6.0 during the reaction. Samples were taken every 24 hours to detect the hexavalent chromium content in the mixed solution. The results were as follows: Figure 1 As shown in the pH=6.0 curve.

[0029] Chitosan was added to an aqueous solution containing 10 mg / mL hexavalent chromium. The concentration of chitosan in the final mixed solution was 2 g / mL. The mixed solution was placed in a constant temperature oscillator and oscillated at 100 rpm / min at 25°C for 168 hours. The pH of the reaction system was controlled to be 7.0 during the reaction. Samples were taken every 24 hours to detect the hexavalent chromium content in the mixed solution. The results were as follows: Figure 1 As shown in the curve at pH=7.0.

[0030] Chitosan was added to an aqueous solution containing 10 mg / mL hexavalent chromium. The concentration of chitosan in the final mixed solution was 2 g / mL. The mixed solution was placed in a constant temperature oscillator and oscillated at 100 rpm / min at 25°C for 168 hours. The pH of the reaction system was controlled to be 8.0 during the reaction. Samples were taken every 24 hours to detect the hexavalent chromium content in the mixed solution. The results were as follows: Figure 1 As shown in the curve at pH=8.0.

[0031] Chitosan was added to an aqueous solution containing 10 mg / mL hexavalent chromium. The concentration of chitosan in the final mixed solution was 2 g / mL. The mixed solution was placed in a constant temperature oscillator and oscillated at 100 rpm / min at 25°C for 168 hours. The pH of the reaction system was controlled to be 9.0 during the reaction. Samples were taken every 24 hours to detect the hexavalent chromium content in the mixed solution. The results were as follows: Figure 1 As shown in the curve at pH=9.0.

[0032] Depend on Figure 1 It can be seen from the curves that when hydrochloric acid is used to control the pH of the water body, the removal efficiency of hexavalent chromium at pH 2.0, 3.5, 4.5, 5.5, 6.0 and 7.0 reaches 3.5%, 13.2%, 85.6%, 30.2%, 9.5%, and 0% respectively at the 24th hour of the reaction, and reaches 20.8%, 53%, 100%, 78.2%, 32%, and 0% respectively at the 7th day of the reaction. Therefore, when the pH is less than 7.0, chitosan can effectively remove hexavalent chromium by controlling the pH of the water body with hydrochloric acid. When the pH is greater than or equal to 7.0, even if hydrochloric acid is used to control the pH of the water body, chitosan has no removal effect on hexavalent chromium.

[0033] Example 2 In this embodiment, the water purification agent includes chitosan and a pH regulator, and the pH regulator is ammonium chloride. The water purifier provided in this embodiment was added to an aqueous solution with a hexavalent chromium content of 10 mg / mL to obtain a mixed solution, wherein the concentration of chitosan was 2 g / mL. The mixed solution was placed in a constant temperature oscillator, and the pH of the water was controlled to 6.5 using ammonium chloride at 25°C. The mixture was oscillated at 100 rpm / min for 168 hours. Samples were taken every 24 hours to detect the hexavalent chromium content in the mixed solution. The results were as follows: Figure 2 Medium 10mg·L -1 Cr(VI) curve shown.

[0034] The water purifier provided in this embodiment was added to an aqueous solution with a hexavalent chromium content of 20 mg / mL to obtain a mixed solution, wherein the concentration of chitosan was 2 g / mL. The mixed solution was placed in a constant temperature oscillator, and the pH of the water was controlled to 6.5 using ammonium chloride at 25°C. The mixture was oscillated at 100 rpm / min for 168 hours. Samples were taken every 24 hours to detect the hexavalent chromium content in the mixed solution. The results were as follows: Figure 2 Medium 20mg·L -1 Cr(VI) curve shown.

[0035] The water purifier provided in this embodiment was added to an aqueous solution with a hexavalent chromium content of 40 mg / mL to obtain a mixed solution, wherein the concentration of chitosan was 2 g / mL. The mixed solution was placed in a constant temperature oscillator, and the pH of the water was controlled to 6.5 using ammonium chloride at 25°C. The mixture was oscillated at 100 rpm / min for 168 hours. The hexavalent chromium content in the mixed solution was detected every 24 hours. The results were as follows: Figure 2 Medium 40mg·L -1 Cr(VI) curve shown.

[0036] At the same time, this embodiment also provides three control experiments, namely: an aqueous solution with a hexavalent chromium content of 10 mg / mL is placed in a constant temperature oscillator without any addition, and oscillated at 100 rpm / min at 25°C for 168 hours. Samples are taken every 24 hours to detect the hexavalent chromium content in the mixed solution. The results are as follows: Figure 2 As shown in the CK curve; Add ammonium chloride to an aqueous solution with a hexavalent chromium content of 10 / mL, and use ammonium chloride to control the pH of the water to 6.5 at 25°C. Place the mixed solution in a constant temperature oscillator and oscillate at 100 rpm / min for 168 hours. Take samples every 24 hours to detect the hexavalent chromium content in the mixed solution. The results are as follows: Figure 2 As shown in the NH4Cl curve; Chitosan was added to the aqueous solution with a hexavalent chromium content of 10 / mL, and the final chitosan concentration was 2g / L. The mixed solution was placed in a constant temperature oscillator and oscillated at 100rpm / min for 168h. Samples were taken every 24h to detect the hexavalent chromium content in the mixed solution. The results were as follows: Figure 2 As shown in the Chitosan curve.

[0037] Depend on Figure 2 It can be seen from the curves that when the water purifier is composed of pH regulator ammonium chloride and chitosan, the removal rates of hexavalent chromium at 24h and 48h are 17.5% and 27%, respectively, which are much higher than those of the three control groups, confirming the feasibility of the water purifier provided in this embodiment to remove hexavalent chromium.

[0038] Example 3 In this embodiment, the water purification agent chitosan and the pH regulator, the pH regulator is potassium dihydrogen phosphate The water purifier provided in this embodiment was added to an aqueous solution with a hexavalent chromium content of 10 mg / mL to obtain a mixed solution, wherein the concentration of chitosan was 2 g / mL. The mixed solution was placed in a constant temperature oscillator, and potassium dihydrogen phosphate was used to control the pH of the water to 6.4 at 20°C. The mixture was oscillated at 200 rpm / min for 168 hours. Samples were taken every 24 hours to detect the hexavalent chromium content in the mixed solution. The results were as follows: Figure 3 Medium 10mg·L -1 Cr(VI) curve shown.

[0039] The water purification agent provided in this embodiment was added to an aqueous solution with a hexavalent chromium content of 20 mg / mL to obtain a mixed solution, wherein the concentration of chitosan was 2 g / mL. The mixed solution was placed in a constant temperature oscillator, and potassium dihydrogen phosphate was used to control the pH of the water to 6.4 at 20°C. The mixture was oscillated at 200 rpm / min for 168 hours. Samples were taken every 24 hours to detect the hexavalent chromium content in the mixed solution. The results were as follows: Figure 3 Medium 20mg·L -1 Cr(VI) curve shown.

[0040] The water purification agent provided in this embodiment was added to an aqueous solution with a hexavalent chromium content of 40 mg / mL to obtain a mixed solution, wherein the concentration of chitosan was 2 g / mL. The mixed solution was placed in a constant temperature oscillator, and potassium dihydrogen phosphate was used to control the pH of the water to 6.4 at 20°C. The mixture was oscillated at 200 rpm / min for 168 hours. Samples were taken every 24 hours to detect the hexavalent chromium content in the mixed solution. The results were as follows: Figure 3 Medium 40mg·L -1 Cr(VI) curve shown.

[0041] At the same time, this embodiment also provides three control experiments, namely: an aqueous solution with a hexavalent chromium content of 10 mg / mL is placed in a constant temperature oscillator without addition, and oscillated at 200 rpm / min for 168 hours. Samples are taken every 24 hours to detect the hexavalent chromium content in the mixed solution. The results are as follows: Figure 3 As shown in the CK curve; Add potassium dihydrogen phosphate to the aqueous solution with a hexavalent chromium content of 10 / mL, and the final potassium dihydrogen phosphate concentration is 1g / L. Place the above mixed solution in a constant temperature oscillator, use potassium dihydrogen phosphate to control the water pH to 6.4 at 20°C, oscillate at 200rpm / min for 168h, and take samples every 24h to detect the hexavalent chromium content in the mixed solution. The results are as follows Figure 3 As shown in the KH2PO4 curve;

[0042] Chitosan was added to the aqueous solution with a hexavalent chromium content of 10 / mL, and the final chitosan concentration was 2g / L. The mixed solution was placed in a constant temperature oscillator and oscillated at 200rpm / min for 168h. Samples were taken every 24h to detect the hexavalent chromium content in the mixed solution. The results were as follows: Figure 3 As shown in the Chitosan curve.

[0043] Depend on Figure 3 It can be seen from the curves that when the water purifier is composed of pH regulator potassium dihydrogen phosphate and chitosan, the removal rates of hexavalent chromium at 24h and 48h reach 88.5% and 96.1%, respectively, which are much higher than those of the three control groups, confirming that the water purifier provided in this embodiment has a very high efficiency in removing hexavalent chromium.

[0044] Example 4 In this embodiment, the water purification agent includes chitosan and a pH regulator, and the pH regulator is sodium dihydrogen phosphate. The water purifier provided in this embodiment was added to an aqueous solution with a hexavalent chromium content of 10 mg / mL to obtain a mixed solution. The final concentration of sodium dihydrogen phosphate in the mixed solution was 1 g / L, and the concentration of chitosan was 2 g / mL. The mixed solution was placed in a constant temperature oscillator, the pH of the water was controlled to be 6.3 at 25°C, and the oscillation was performed at 200 rpm / min for 168 hours. The hexavalent chromium content in the mixed solution was detected every 24 hours. The results are as follows: Figure 4 Medium 10mg·L -1 Cr(VI) curve shown.

[0045] The water purifier provided in this embodiment was added to an aqueous solution containing 20 mg / mL of hexavalent chromium to obtain a mixed solution. The final concentration of sodium dihydrogen phosphate in the mixed solution was 1 g / L, and the concentration of chitosan was 2 g / mL. The mixed solution was placed in a constant temperature oscillator, the pH of the water was controlled to be 6.3 at 25°C, and the oscillation was performed at 200 rpm / min for 168 hours. Samples were taken every 24 hours to detect the hexavalent chromium content in the mixed solution. The results were as follows: Figure 4 Medium 20mg·L -1 Cr(VI) curve shown.

[0046] The water purifier provided in this embodiment was added to an aqueous solution containing 40 mg / mL of hexavalent chromium to obtain a mixed solution. The final concentration of sodium dihydrogen phosphate in the mixed solution was 1 g / L, and the concentration of chitosan was 2 g / mL. The mixed solution was placed in a constant temperature oscillator, the pH of the water was controlled to be 6.3 at 25°C, and the oscillation was performed at 200 rpm / min for 168 hours. The hexavalent chromium content in the mixed solution was detected every 24 hours. The results were as follows: Figure 4 Medium 40mg·L -1 Cr(VI) curve shown.

[0047] At the same time, this embodiment also provides three control experiments, namely: an aqueous solution with a hexavalent chromium content of 10 mg / mL is placed in a constant temperature oscillator without any addition, and oscillated at 200 rpm / min for 168 hours. Samples are taken every 24 hours to detect the hexavalent chromium content in the mixed solution. The results are as follows: Figure 4 As shown in the CK curve; Sodium dihydrogen phosphate was added to the aqueous solution with a hexavalent chromium content of 10 / mL, and the final sodium dihydrogen phosphate concentration was 1g / L. The mixed solution was placed in a constant temperature oscillator and oscillated at 200rpm / min for 168h. Samples were taken every 24h to detect the hexavalent chromium content in the mixed solution. The results were as follows: Figure 4 As shown in the NaH2PO4 curve;

[0048] Chitosan was added to the aqueous solution with a hexavalent chromium content of 10 / mL, and the final chitosan concentration was 2g / L. The mixed solution was placed in a constant temperature oscillator and oscillated at 200rpm / min for 168h. Samples were taken every 24h to detect the hexavalent chromium content in the mixed solution. The results were as follows: Figure 4 As shown in the Chitosan curve.

[0049] Depend on Figure 4 It can be seen from the curves that when the water purifier is composed of the pH regulator sodium dihydrogen phosphate and chitosan, the removal rates of hexavalent chromium at 24h and 48h reach 88.5% and 96.1%, respectively, which are much higher than those of the three control groups, confirming that the water purifier provided in this embodiment has a very high efficiency in removing hexavalent chromium.

[0050] Although the disclosure is disclosed as above, the protection scope of the disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the disclosure, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A method for removing hexavalent chromium from water, characterized in that: The following steps are involved: A water purifier is added to water containing hexavalent chromium, the water is shaken or stirred while the pH value of the water is controlled to be 3.5-7, and the water after the shaking or stirring is filtered to remove the hexavalent chromium in the water. The water purifier includes chitosan.

2. The method according to claim 1, characterized in that After adding water purifier, the concentration of chitosan in water is 0.1~50g / L.

3. The method according to claim 1, characterized in that The concentration of hexavalent chromium in the water containing hexavalent chromium is greater than or equal to 0.1 mg / mL.

4. The method according to claim 1, characterized in that The water purifier also includes a pH regulator, which is an acid, an acid salt or a buffer salt.

5. The method according to claim 1, characterized in that The duration of the oscillation or stirring treatment is 1 min to 168 h.

6. The method according to claim 1, characterized in that The speed of oscillation or stirring is 10~300rpm / min.

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