A method of manufacturing a non-harmful heavy metal activated zeolite

Abstract

The application discloses a method for manufacturing activated zeolite without harmful heavy metals, which comprises the following specific operation steps: S1: selecting alkali modified and dredged natural zeolite, and preparing a solution by mixing the natural zeolite, wherein the solid content of the prepared solution is 1%-50%, the pH of the solution system is adjusted to 12.5-13.5 by using alkali, and stirring is carried out; S2: while stirring the solution, phosphoric acid is added to maintain the pH of the solution to be 5.0-8.5 for reaction, after the reaction, repeated cleaning is carried out until the pH of the cleaning solution is neutral, and then the modified natural zeolite is separated from the solution; and S3: the obtained modified natural zeolite is taken to prepare a solution, the solid content of the modified natural zeolite in the solution is 1%-50%, a ferrous salt is dissolved in hydrochloric acid to prepare a solution, hydroxylamine hydrochloride is added, and the modified natural zeolite solution is mixed with the ferrous salt solution, the hydrochloric acid solution and the hydroxylamine hydrochloride solution. The natural zeolite is modified by using an alkali solution first, the alkali solution not only dredges the pore channel of the natural zeolite and increases the specific surface area of the natural zeolite, but also significantly reduces the aluminum dissolution of the natural zeolite in a simulated gastric acid solution system.

Description

Technical Field

[0001] This invention relates to the technical field of zeolite treatment methods, specifically a method for manufacturing activated zeolite free of harmful heavy metals. Background Technology

[0002] According to incomplete statistics, nearly 400 natural zeolite deposits have been discovered in my country, with a total reserve of approximately 3 billion tons. There are many types of natural zeolite, with more than 80 different types existing in nature. Different types of zeolite have different properties and applications. Natural zeolite is resistant to acids and alkalis and has excellent stability, ion exchange, hemostatic properties, and the ability to adsorb harmful substances. Natural zeolite is widely used in wastewater treatment, soil improvement, air purification, ion exchange materials, catalysts, animal feed, cosmetics, medical devices, and other fields.

[0003] Zeolite, as a feed additive, can enhance the activity of some enzymes in animals, improve antioxidant capacity, reduce harmful substances such as aflatoxin and heavy metals in the body, alleviate the body's nitrate burden, and reduce ammonia in feces, which is beneficial to the colonic microbiota and epithelial cells. In addition, zeolite also has nutritional value; adding 5% zeolite powder to feed can accelerate the growth of poultry and livestock, resulting in stronger bodies, fresher meat, and higher egg production. Zeolite is acid and alkali resistant, possesses excellent stability, ion exchange and hemostatic properties, and the ability to adsorb harmful substances. When added to feed and entering the animal's gastrointestinal tract, harmful heavy metals such as lead, mercury, and cadmium, as well as radioactive elements such as cesium, radium, and strontium, are captured and fixed in the zeolite's porous structure and excreted with feces. Adding it to feed helps eliminate harmful heavy metals from the animal's gastrointestinal tract, making the animal healthier. However, unmodified zeolite can leach aluminum under acidic conditions, increasing aluminum intake in animals and causing adverse effects. Zeolite's excellent ion exchange properties can even adsorb and excrete beneficial elements (such as calcium, iron, and zinc) from the animal's body, leading to insufficient daily intake of these elements and impacting animal health. Currently, my country's feed hygiene standards only specify the threshold for arsenic in zeolite; thresholds for other harmful heavy metals are not specified. The lack of thresholds for harmful heavy metals (lead, mercury, cadmium, etc.) in zeolite as a feed additive may result in elevated levels of other harmful heavy metals in feed, affecting its quality. Furthermore, zeolite is widely used as a raw material in cosmetics because it can effectively adsorb many harmful substances in human skin, providing excellent skin cleansing effects. According to my country's "Cosmetic Safety Technical Specifications," the relevant limits for harmful heavy metals in cosmetics are: lead ≤10 mg / kg, mercury ≤1 mg / kg, arsenic ≤2 mg / kg, and cadmium ≤5 mg / kg. However, there are no specified limits for harmful heavy metals (lead, arsenic, mercury, cadmium) in zeolite used as a cosmetic raw material. High levels of these harmful heavy metals in zeolite can lead to high levels of harmful heavy metals in cosmetics, affecting their quality. As people's living standards improve, the limits for harmful substances in zeolite used as feed additives and cosmetic raw materials will gradually increase. Therefore, inventing a technology to remove harmful heavy metals from zeolite has significant social value.

[0004] Early studies largely focused on using zeolite to treat (adsorb) wastewater or soil contaminated with heavy metals. Some literature reported the use of complexing or chelating agents to remove heavy metal-contaminated soil through leaching; a few studies also reported the removal of arsenic from wastewater using modified zeolite. No literature reports methods for completely removing harmful heavy metals such as lead, arsenic, mercury, and cadmium from natural zeolite, or methods for addressing aluminum dissolution from zeolite under acidic conditions and inhibiting or reducing the adsorption and excretion of beneficial elements (such as calcium, iron, and zinc).

[0005] Zeolite is an aluminosilicate. Natural zeolite has a complex composition, and numerous studies have shown that it contains high levels of harmful heavy metals such as lead, arsenic, mercury, and cadmium. Some harmful heavy metals, such as lead and arsenic, can reach or exceed 15 mg / kg. The addition of untreated natural zeolite to feed and cosmetics contributes to the high heavy metal content in these products. Natural zeolite exhibits various ion dissolution and ion exchange processes in solution systems, making these processes unavoidable. Harmful heavy metals such as lead, mercury, and cadmium in natural zeolite are cations. Arsenic has a complex valence state. Generally, the harmful heavy metal arsenic in natural zeolite is similar to that in soil, primarily trivalent and pentavalent arsenic. Arsenic in natural zeolite exists in various forms, including water-soluble arsenic, weakly adsorbed arsenic, strongly adsorbed arsenic, amorphous iron-aluminum oxide bound arsenic, crystalline iron-aluminum oxide bound arsenic, and calcium-bound arsenic. Except for water-soluble and weakly adsorbed arsenic, other bound arsenic forms are difficult to physically separate from natural zeolite. Natural zeolites contain a certain amount of iron (or ferrous iron) and calcium. Therefore, calcium ions and iron (or ferrous iron) ions are dissolved in the natural zeolite solution system. Oxygen is inevitably present in the solution system. The ferrous iron dissolved from the natural zeolite is easily oxidized into ferric ions (which combine with the ferric ions dissolved in the natural zeolite) and combine with the dissolved harmful heavy metal arsenate ions (or arsenite ions) to continue forming insoluble precipitates. Therefore, the harmful heavy metal arsenic cannot be effectively physically separated from the natural zeolite. The complex composition of natural zeolite and the easy formation of insoluble arsenic make the removal of arsenic from natural zeolite very difficult. Therefore, removing harmful heavy metals from natural zeolite is very difficult and presents a huge challenge.

[0006] Natural zeolites contain high levels of silicon and aluminum, resulting in significant aluminum leaching under animal gastric acid conditions. Therefore, preparing zeolites free of harmful heavy metals that exhibit low aluminum leaching, strong adsorption of harmful heavy metals, and excellent hemostatic properties under simulated gastric acid conditions presents a significant challenge and difficulty, while also holding important social significance. Summary of the Invention

[0007] (a) Technical problems to be solved

[0008] To address the shortcomings of existing technologies, this invention provides a method for manufacturing activated zeolite free of harmful heavy metals, thereby solving the problems mentioned in the background art, such as the great difficulty in removing arsenic from natural zeolite, the difficulty in removing excessive levels of harmful heavy metals from natural zeolite, and the great challenges and difficulties in preparing zeolite free of harmful heavy metals with low aluminum dissolution under gastric acid conditions, strong adsorption of harmful heavy metals, and excellent hemostatic properties.

[0009] (II) Technical Solution

[0010] To achieve the above objectives, the present invention provides the following technical solution: a method for manufacturing activated zeolite free of harmful heavy metals, comprising the following specific operational steps:

[0011] S1: Select alkali-modified and unblocking natural zeolite, and prepare a solution with natural zeolite. The solid content of the prepared solution is 1%-50%. Use alkali to adjust the pH of the solution system to maintain it between 12.5-13.5 and stir.

[0012] S2: While stirring the solution, add phosphoric acid to maintain the pH value of the solution between 5.0 and 8.5 for the reaction. After the reaction, repeatedly wash until the pH value of the washing solution is neutral, and then separate the modified natural zeolite from the solution.

[0013] S3: Take the modified natural zeolite obtained above and prepare a solution with a solid content of 1%-50% in the modified natural zeolite. Dissolve the ferrous salt in hydrochloric acid to prepare a solution, and then add hydroxylamine hydrochloride. Mix the modified natural zeolite solution with the ferrous salt, hydrochloric acid and hydroxylamine hydrochloride solution, and adjust the pH of the solution to 2.5-4 with acetic acid and react for a period of time.

[0014] S4: Add a complexing agent to the mixed solution after step S3, adjust the pH of the solution to between 1.0 and 4.0 with acetic acid, stir and react for a period of time, then separate the modified natural zeolite from the solution, and then wash repeatedly until the pH of the washing solution is neutral and separate again.

[0015] S5: After separating the modified natural zeolite from the solution, the resulting solution is mixed with the solution containing the oxidant and stirred to react. Alkali solution is added to separate the harmful heavy metal precipitate from the solution.

[0016] S6: Prepare a solution of the above-mentioned modified natural zeolite with a solid content between 1% and 50%. Add calcium ions, iron ions, and zinc ions to the modified natural zeolite. Finally, separate the modified natural zeolite from the solution. Then, wash repeatedly until the pH of the washing solution is neutral and separate again. The obtained modified natural zeolite free of harmful heavy metals is dried at 110℃ and then activated at 350℃-550℃ to obtain activated natural zeolite free of harmful heavy metals.

[0017] As a further step of the present invention, the alkali used in step S1 is sodium hydroxide, potassium hydroxide or ammonia.

[0018] As a further step of the present invention, the separation method in steps S3 and S4 is either static sedimentation for 6-24 hours followed by filtration or centrifugal filtration.

[0019] As a further step of the present invention, the oxidant in step S5 is set as one or more of hydrogen peroxide, sodium percarbonate, ozone, sodium hypochlorite or potassium nitrate.

[0020] As a further step of the present invention, the molar mass ratio of ferrous ions to hydroxylamine hydrochloride in step S3 is 10:1-100:1, and the mass ratio of modified natural zeolite to ferrous ions in the modified natural zeolite solution and the mixture of ferrous salt and hydroxylamine hydrochloride is 5:1-100:1.

[0021] As a further step of the present invention, the complexing agent in S4 is one or more complexing agents or chelating agents, and the mass ratio of modified natural zeolite to complexing agent or chelating agent is 10:1-200:1.

[0022] As a further step of the present invention, the chelating agent includes, but is not limited to, citric acid, ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetic acid, diethylenetriaminepentatriacetic acid and diethyltriacetic acid, organic acids and phytic acid, and the complexing agent includes, but is not limited to, aziridine triacetic acid and hydroxyethylenediaminetriacetic acid.

[0023] (III) Beneficial Effects

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] This invention first modifies natural zeolite using an alkaline solution. The alkaline solution not only effectively opens the pores of the natural zeolite, increasing its specific surface area, but also significantly reduces aluminum dissolution in gastric acid solutions and promotes the dissolution of the harmful heavy metal arsenic. Phosphoric acid is used to adjust the pH of the reaction system. The increased concentration of phosphate ions in the solution significantly allows phosphate ions to displace arsenate ions (of the same group) from the natural zeolite into the solution, further removing the harmful heavy metal arsenic. The arsenic dissolution from the natural zeolite into the solution facilitates separation of the natural zeolite from the solution. Simple static sedimentation to remove the supernatant and filtration, or centrifugation, are sufficient to separate the modified natural zeolite from the solution. The resulting modified natural zeolite is then cleaned by adding an appropriate amount of deionized water, stirring, allowing it to settle naturally, discarding the supernatant, and filtration or centrifugation. The production equipment is simple and very easy to operate. The phosphate content of the modified natural zeolite can be significantly reduced through cleaning.

[0026] This invention allows other harmful heavy metals in natural zeolite to continuously dissolve. By allowing the zeolite to settle naturally, discarding the supernatant, and filtering or centrifuging, the modified natural zeolite can be completely separated from the harmful heavy metals. The solution and washing liquid obtained from the separation from the modified natural zeolite are then mixed with the solution containing the oxidant to oxidize highly toxic trivalent arsenic into less toxic pentavalent arsenic and ferrous ions into ferric ions. By making full use of the low solubility of ferric arsenate, some harmful heavy metals can be precipitated and recovered, thus avoiding environmental pollution.

[0027] Ferrous zeolite was prepared by modifying natural zeolite with ferrous ions. Under the combined action of hydroxylamine hydrochloride and ferrous ions, the sparingly soluble harmful heavy metal arsenic in the natural zeolite was further reduced and dissolved, forming a relatively highly soluble arsenite salt. This significantly achieved the dissolution and stable existence of various bound arsenic forms and sparingly soluble arsenic in the solution system, realizing the physical separation of natural zeolite from the harmful heavy metal arsenic. Under acidic conditions, the addition of appropriate complexing or chelating agents significantly achieved the separation of other heavy metals from the natural zeolite. After modification with calcium, iron, and zinc ions and separation from the solution, the natural zeolite was repeatedly washed, dried, and then calcined at high temperature to further open up the pores of the natural zeolite. The multi-step reaction process was carried out at room temperature or with appropriate heating, resulting in a mild reaction process. The supernatant was removed by natural sedimentation followed by filtration or centrifugation. The production process was simple and easy to operate, requiring minimal equipment investment and low energy consumption.

[0028] Natural zeolite was modified with alkaline solution to open its pores, modified with hydroxylamine hydrochloride and ferrous ions, treated with chelating and complexing agents, and finally modified with calcium, iron, and zinc ions. After drying and high-temperature activation, the resulting modified natural zeolite, free of harmful heavy metals, showed a significant reduction in aluminum leaching under simulated gastric acid solution conditions. It also showed minimal adsorption of iron, calcium, and zinc ions added to the simulated gastric acid solution, maintained good hemostatic efficacy, and significantly increased specific surface area. Harmful heavy metals such as lead, arsenic, mercury, and cadmium in the natural zeolite were significantly reduced or completely removed. As a raw material for feed and cosmetics, it can significantly reduce the content of harmful heavy metals in feed and cosmetics, improve product quality, and has significant social value. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] Implementation Method 1:

[0031] This invention first modifies natural zeolite using an alkali (such as sodium hydroxide, potassium hydroxide, or ammonia). The sodium hydroxide concentration is 1M-2M, and the solid content of the natural zeolite solution is 1%-10%. The pH of the solution system is adjusted using sodium hydroxide solution and maintained between 11.5 and 13.5. The reaction is carried out at room temperature or with appropriate heating and stirring for 8-24 hours. An appropriate amount of phosphoric acid is added to the solution to maintain the pH between 5.0 and 8.5, and the reaction is carried out at room temperature or with appropriate heating for 8-24 hours. The modified natural zeolite is then separated from the solution, for example, by allowing it to settle naturally for 6-24 hours, removing the supernatant, and then filtering or centrifuging to remove the supernatant. Water is then added and the solution is repeatedly washed until the pH of the washing liquid is neutral. The solution is then allowed to settle naturally, filtered, or centrifuged. After the natural zeolite is separated from the solution, the solution and washing liquid are collected, and an appropriate amount of oxidant is added and stirred appropriately for later use. The oxidant can be one or more of hydrogen peroxide, sodium percarbonate, ozone, sodium hypochlorite, or potassium nitrate.

[0032] The obtained modified natural zeolite was dissolved in water to form a solution with a solid content of 1%-10%. An appropriate amount of ferrous salt (Fe) was then added. 2+ A solution of ferrous salt (0.1-2M) is prepared by dissolving it in hydrochloric acid, and hydroxylamine hydrochloride (NH₂OH·HCl) is added. The molar ratio of ferrous ions to hydroxylamine hydrochloride is 10:1-100:1. The modified natural zeolite solution is mixed with the ferrous salt and hydroxylamine hydrochloride, and the mass ratio of modified natural zeolite to ferrous ions in the mixed solution is 5:1-100:1. The pH of the solution is adjusted to 2.5-4 with saline or acetic acid, and the reaction is carried out at room temperature or by heating for 8-24 hours. Then, an appropriate amount of EDTA is added to the mixed solution. The modified natural zeolite and EDTA are reacted at a mass ratio of 10:1 to 200:1. The pH of the solution is adjusted to 1.0-4.0 using hydrochloric acid or acetic acid, and the ionic strength is adjusted using sodium chloride. The mixture is stirred and reacted at room temperature or with appropriate heating for 8-24 hours. The natural zeolite is then separated from the solution, for example, by allowing it to settle naturally for 6-24 hours, removing the supernatant, and then filtering, or by centrifuging and removing the supernatant. Water is then added and the mixture is repeatedly washed until the pH of the washing solution is neutral. The mixture is then allowed to settle naturally, filtered, and the supernatant is removed, or by centrifugation and removing the supernatant. After separating the natural zeolite from the solution, the resulting solution and washing solution are mixed with the solution containing the oxidant and stirred to react. An appropriate amount of alkali solution is added to precipitate harmful heavy metals in the solution, facilitating their separation and preventing environmental pollution.

[0033] Prepare a solution using an appropriate amount of the modified natural zeolite with a heavy metal removal content between 1% and 50%. Then, add appropriate amounts of calcium, iron, and zinc ions to the modified natural zeolite with harmful heavy metal removal. Finally, separate the modified natural zeolite from the solution, for example, by allowing it to settle naturally for 6-24 hours to remove the supernatant and then filtering, or by centrifuging to remove the supernatant. After that, repeatedly wash with water until the pH of the washing solution is neutral, then allow it to settle naturally to remove the supernatant and then filter or centrifuge to remove the supernatant. The resulting modified natural zeolite with no (or low) harmful heavy metals is dried at 110℃ and then activated at 350℃-550℃ to obtain activated natural zeolite with no (or low) harmful heavy metals.

[0034] Implementation Method 2:

[0035] This invention first modifies natural zeolite using an alkali (such as sodium hydroxide, potassium hydroxide, or ammonia). The sodium hydroxide concentration is 1M-2M, and the solid content of the natural zeolite solution is 1%-10%. The pH of the solution system is adjusted using sodium hydroxide solution and maintained between 8.5 and 11.0. The reaction is carried out at room temperature or with appropriate heating and stirring for 8-24 hours. An appropriate amount of phosphoric acid is added to the solution to maintain the pH between 5.0 and 8.5, and the reaction is carried out at room temperature or with appropriate heating for 8-24 hours. The modified natural zeolite is then separated from the solution, for example, by allowing it to settle naturally for 6-24 hours, removing the supernatant, and then filtering or centrifuging to remove the supernatant. Water is then added and the solution is repeatedly washed until the pH of the washing liquid is neutral. The solution is then allowed to settle naturally, filtered, or centrifuged. After the natural zeolite is separated from the solution, the solution and washing liquid are collected, and an appropriate amount of oxidant is added and stirred appropriately for later use. The oxidant can be one or more of hydrogen peroxide, sodium percarbonate, ozone, sodium hypochlorite, or potassium nitrate.

[0036] The obtained modified natural zeolite was dissolved in water to form a solution with a solid content of 1%-10%. An appropriate amount of ferrous salt (Fe) was then added. 2+A solution of ferrous salt (0.1-2M) is prepared by dissolving it in hydrochloric acid, and hydroxylamine hydrochloride (NH₂OH·HCl) is added. The molar ratio of ferrous ions to hydroxylamine hydrochloride is 10:1-100:1. The modified natural zeolite solution is mixed with the ferrous salt and hydroxylamine hydrochloride, and the mass ratio of modified natural zeolite to ferrous ions in the mixed solution is 5:1-100:1. The pH of the solution is adjusted to 2.5-4 with saline or acetic acid, and the reaction is carried out at room temperature or by heating for 8-24 hours. Then, an appropriate amount of EDTA is added to the mixed solution. The modified natural zeolite and EDTA are reacted at a mass ratio of 10:1 to 200:1. The pH of the solution is adjusted to 1.0-4.0 using hydrochloric acid or acetic acid, and the ionic strength is adjusted using sodium chloride. The mixture is stirred and reacted at room temperature or with appropriate heating for 8-24 hours. The natural zeolite is then separated from the solution, for example, by allowing it to settle naturally for 6-24 hours, removing the supernatant, and then filtering, or by centrifuging and removing the supernatant. Water is then added and the mixture is repeatedly washed until the pH of the washing solution is neutral. The mixture is then allowed to settle naturally, filtered, and the supernatant is removed, or by centrifugation and removing the supernatant. After separating the natural zeolite from the solution, the resulting solution and washing solution are mixed with the solution containing the oxidant and stirred to react. An appropriate amount of alkali solution is added to precipitate harmful heavy metals in the solution, facilitating their separation and preventing environmental pollution.

[0037] Prepare a solution using an appropriate amount of the modified natural zeolite with a heavy metal removal content between 1% and 50%. Then, add appropriate amounts of calcium, iron, and zinc ions to the modified natural zeolite with harmful heavy metal removal. Finally, separate the modified natural zeolite from the solution, for example, by allowing it to settle naturally for 6-24 hours to remove the supernatant and then filtering, or by centrifuging to remove the supernatant. After that, repeatedly wash with water until the pH of the washing solution is neutral, then allow it to settle naturally to remove the supernatant and then filter or centrifuge to remove the supernatant. The resulting modified natural zeolite with no (or low) harmful heavy metals is dried at 110℃ and then activated at 350℃-550℃ to obtain activated natural zeolite with no (or low) harmful heavy metals.

[0038] The difference between Implementation Method 2 and Implementation Method 1 is that the amount of alkali-modified natural zeolite added is insufficient. After the amount of alkali added is reduced, the pH range of the solution decreases. The pH range decreases from 11.5-13.0 in Implementation Method 1 to 8.5-11.0 in Implementation Method 2. Other test conditions are the same. Under gastric acid solution conditions, the aluminum content of the modified natural zeolite without (or with) harmful heavy metals increases from 0.01 mg / g in Implementation Method 1 to 2.30 mg / g in Implementation Method 2.

[0039] Implementation Method 3:

[0040] This invention first modifies natural zeolite using an alkali (such as sodium hydroxide, potassium hydroxide, or ammonia). The sodium hydroxide concentration is 1M-2M, and the solid content of the natural zeolite solution is 1%-10%. The pH of the solution system is adjusted using sodium hydroxide solution and maintained between 11.5 and 13.5. The reaction is carried out at room temperature or with appropriate heating and stirring for 8-24 hours. An appropriate amount of phosphoric acid is added to the solution to maintain the pH between 9.0 and 11.5, and the reaction is carried out at room temperature or with appropriate heating for 8-24 hours. The modified natural zeolite is then separated from the solution, for example, by allowing it to settle naturally for 6-24 hours, removing the supernatant, and then filtering or centrifuging to remove the supernatant. Water is then added and the solution is repeatedly washed until the pH of the washing liquid is neutral. The solution is then allowed to settle naturally, filtered, or centrifuged. After the natural zeolite is separated from the solution, the solution and washing liquid are collected, and an appropriate amount of oxidant is added and stirred appropriately for later use. The oxidant can be one or more of hydrogen peroxide, sodium percarbonate, ozone, sodium hypochlorite, or potassium nitrate.

[0041] The obtained modified natural zeolite was dissolved in water to form a solution with a solid content of 1%-10%. An appropriate amount of ferrous salt (Fe) was then added. 2+ A solution of ferrous salt (0.1-2M) is prepared by dissolving it in hydrochloric acid, and hydroxylamine hydrochloride (NH₂OH·HCl) is added. The molar ratio of ferrous ions to hydroxylamine hydrochloride is 10:1-100:1. The modified natural zeolite solution is mixed with the ferrous salt and hydroxylamine hydrochloride, and the mass ratio of modified natural zeolite to ferrous ions in the mixed solution is 5:1-100:1. The pH of the solution is adjusted to 2.5-4 with saline or acetic acid, and the reaction is carried out at room temperature or by heating for 8-24 hours. Then, an appropriate amount of EDTA is added to the mixed solution. The modified natural zeolite and EDTA are reacted at a mass ratio of 10:1 to 200:1. The pH of the solution is adjusted to 1.0-4.0 using hydrochloric acid or acetic acid, and the ionic strength is adjusted using sodium chloride. The mixture is stirred and reacted at room temperature or with appropriate heating for 8-24 hours. The natural zeolite is then separated from the solution, for example, by allowing it to settle naturally for 6-24 hours, removing the supernatant, and then filtering, or by centrifuging and removing the supernatant. Water is then added and the mixture is repeatedly washed until the pH of the washing solution is neutral. The mixture is then allowed to settle naturally, filtered, and the supernatant is removed, or by centrifugation and removing the supernatant. After separating the natural zeolite from the solution, the resulting solution and washing solution are mixed with the solution containing the oxidant and stirred to react. An appropriate amount of alkali solution is added to precipitate harmful heavy metals in the solution, facilitating their separation and preventing environmental pollution.

[0042] Prepare a solution using an appropriate amount of the modified natural zeolite with a heavy metal removal content between 1% and 50%. Then, add appropriate amounts of calcium, iron, and zinc ions to the modified natural zeolite with harmful heavy metal removal. Finally, separate the modified natural zeolite from the solution, for example, by allowing it to settle naturally for 6-24 hours to remove the supernatant and then filtering, or by centrifuging to remove the supernatant. After that, repeatedly wash with water until the pH of the washing solution is neutral, then allow it to settle naturally to remove the supernatant and then filter or centrifuge to remove the supernatant. The resulting modified natural zeolite with no (or low) harmful heavy metals is dried at 110℃ and then activated at 350℃-550℃ to obtain activated natural zeolite with no (or low) harmful heavy metals.

[0043] The difference between Implementation Method 3 and Implementation Method 1 lies in the addition of phosphoric acid after the alkali-modified natural zeolite reaction has proceeded for a certain period, resulting in a decrease in the pH value of the solution. Specifically, less phosphoric acid is added after the alkali-modified natural zeolite reaction, leading to insufficient phosphoric acid addition and a pH range that increases from 5.0-8.5 in Implementation Method 1 to 9.0-11.5 in Implementation Method 3. The arsenic content in the natural zeolite obtained in Implementation Method 3 (3.39 mg / g) is higher than that in Implementation Method 1 (0.48 mg / g). This is mainly due to the low concentration of phosphate ions, resulting in insufficient replacement of the arsenic homologue.

[0044] Implementation Method 4:

[0045] This invention first modifies natural zeolite using an alkali (such as sodium hydroxide, potassium hydroxide, or ammonia). The sodium hydroxide concentration is 1M-2M, and the solid content of the natural zeolite solution is 1%-10%. The pH of the solution system is adjusted using sodium hydroxide solution and maintained between 11.5 and 13.5. The reaction is carried out at room temperature or with appropriate heating and stirring for 8-24 hours. An appropriate amount of phosphoric acid is added to the solution to maintain the pH between 5.0 and 8.5, and the reaction is carried out at room temperature or with appropriate heating for 8-24 hours. The modified natural zeolite is then separated from the solution, for example, by allowing it to settle naturally for 6-24 hours, removing the supernatant, and then filtering or centrifuging to remove the supernatant. Water is then added and the solution is repeatedly washed until the pH of the washing liquid is neutral. The solution is then allowed to settle naturally, filtered, or centrifuged. After the natural zeolite is separated from the solution, the solution and washing liquid are collected, and an appropriate amount of oxidant is added and stirred appropriately for later use. The oxidant can be one or more of hydrogen peroxide, sodium percarbonate, ozone, sodium hypochlorite, or potassium nitrate.

[0046] The obtained modified natural zeolite was dissolved in water to form a solution with a solid content of 1%-10%. An appropriate amount of ferrous salt (Fe) was then added. 2+Dissolve the modified natural zeolite (0.1-2M) in hydrochloric acid to prepare a solution. Mix the natural zeolite solution with the ferrous ion solution, with a mass ratio of modified natural zeolite to ferrous ions of 5:1-100:1. Adjust the pH of the solution to 2.5-4 with saline or acetic acid and react at room temperature or with heating for 8-24 hours. Then add an appropriate amount of EDTA to the mixed solution, with a mass ratio of modified natural zeolite to EDTA of 10:1-200:1. Adjust the pH of the solution to 1.0-4.0 with hydrochloric acid or acetic acid and adjust the ionic strength of the solution with sodium chloride. Stir and react at room temperature or with appropriate heating for 8-24 hours. Then separate the natural zeolite from the solution, for example, by allowing it to settle naturally for 6-24 hours, removing the supernatant and then filtering, or by centrifuging and removing the supernatant. Then wash repeatedly with water until the pH of the washing solution is neutral, and then allow it to settle naturally, filter to remove the supernatant and then filter again, or by centrifuging and removing the supernatant. After separating the natural zeolite from the solution, the resulting solution and washing liquid are mixed and stirred with the solution containing the oxidant. An appropriate amount of alkali solution is added to precipitate the harmful heavy metals in the solution, making it easier to separate them from the solution and avoid polluting the environment with harmful heavy metals.

[0047] Prepare a solution using an appropriate amount of the modified natural zeolite with a heavy metal removal content between 1% and 50%. Then, add appropriate amounts of calcium, iron, and zinc ions to the modified natural zeolite with harmful heavy metal removal. Finally, separate the modified natural zeolite from the solution, for example, by allowing it to settle naturally for 6-24 hours to remove the supernatant and then filtering, or by centrifuging to remove the supernatant. After that, repeatedly wash with water until the pH of the washing solution is neutral, then allow it to settle naturally to remove the supernatant and then filter or centrifuge to remove the supernatant. The resulting modified natural zeolite with no (or low) harmful heavy metals is dried at 110℃ and then activated at 350℃-550℃ to obtain activated natural zeolite with no (or low) harmful heavy metals.

[0048] The difference between Implementation Method 4 and Implementation Method 1 is that the weak oxidant hydroxylamine hydrochloride was not added to the ferrous salt solution; all other reaction conditions were the same. In Implementation Method 4, EDTA solution was added as a chelating agent and reacted for a period of time. Analysis of the solution revealed the presence of a certain amount of ferric iron. The resulting modified natural zeolite was free of (or low in) harmful heavy metals. The arsenic content in the natural zeolite obtained through Implementation Method 4 was 6.44 mg / g, higher than the 0.48 mg / g in Implementation Method 1. Implementation Method 4's removal of harmful heavy metals was less effective than Implementation Method 1. The main reason for this may be that the dissolved harmful heavy metal arsenic re-formed with iron ions to form a new precipitate mixed in with the natural zeolite.

[0049] Implementation Method 5:

[0050] This invention first modifies natural zeolite using an alkali (such as sodium hydroxide, potassium hydroxide, or ammonia). The sodium hydroxide concentration is 1M-2M, and the solid content of the natural zeolite solution is 1%-10%. The pH of the solution system is adjusted using sodium hydroxide solution and maintained between 11.5 and 13.5. The reaction is carried out at room temperature or with appropriate heating and stirring for 8-24 hours. An appropriate amount of phosphoric acid is added to the solution to maintain the pH between 5.0 and 8.5, and the reaction is carried out at room temperature or with appropriate heating for 8-24 hours. The modified natural zeolite is then separated from the solution, for example, by allowing it to settle naturally for 6-24 hours, removing the supernatant, and then filtering or centrifuging to remove the supernatant. Water is then added and the solution is repeatedly washed until the pH of the washing liquid is neutral. The solution is then allowed to settle naturally, filtered, or centrifuged. After the natural zeolite is separated from the solution, the solution and washing liquid are collected, and an appropriate amount of oxidant is added and stirred appropriately for later use. The oxidant can be one or more of hydrogen peroxide, sodium percarbonate, ozone, sodium hypochlorite, or potassium nitrate.

[0051] The modified natural zeolite is then prepared into a solution with a solid content of 1%-10%. An appropriate amount of hydroxylamine hydrochloride (NH₂OH.HCl) is added, with a mass ratio of modified natural zeolite solution to hydroxylamine hydrochloride of 10:1-200:1. The pH of the solution is adjusted to 2.5-4 using saline or acetic acid, and the reaction is carried out at room temperature or by heating for 8-24 hours. An appropriate amount of EDTA is then added to the mixed solution, with a mass ratio of modified natural zeolite to EDTA of 10:1-200:1. The pH of the solution is adjusted to 1.0-4.0 using hydrochloric acid or acetic acid, and the ionic strength is adjusted using sodium chloride. The mixture is stirred and reacted at room temperature or by appropriate heating for 8-24 hours. The natural zeolite is then separated from the solution, for example, by allowing it to settle naturally for 6-24 hours to remove the supernatant and then filtering, or by centrifuging to remove the supernatant. Water is then added and the solution is repeatedly washed until the pH of the washing liquid is neutral. The solution is then allowed to settle naturally, filtered to remove the supernatant, and then filtered again, or by centrifuging to remove the supernatant. After separating the natural zeolite from the solution, the resulting solution and washing liquid are mixed and stirred with the solution containing the oxidant. An appropriate amount of alkali solution is added to precipitate the harmful heavy metals in the solution, making it easier to separate them from the solution and avoid polluting the environment with harmful heavy metals.

[0052] Prepare a solution using an appropriate amount of the modified natural zeolite for removing heavy metals, with a solid content between 1% and 50%. Then, add appropriate amounts of calcium, iron, and zinc ions to the modified natural zeolite for removing harmful heavy metals. Finally, separate the modified natural zeolite from the solution, for example, by allowing it to settle naturally for 6-24 hours, removing the supernatant, and then filtering, or by centrifuging to remove the supernatant. Afterward, repeatedly wash with water until the pH of the washing solution is neutral, then allow it to settle naturally to remove the supernatant, and then filter or centrifuge to remove the supernatant. The resulting modified natural zeolite free of (or low in) harmful heavy metals is dried at 110℃, and then activated at 350℃-550℃ to obtain activated natural zeolite free of (or low in) harmful heavy metals.

[0053] The difference between Implementation Method 5 and Implementation Method 1 is that ferrous ions were not added to modify the natural zeolite; only hydroxylamine hydrochloride was added, while other reaction conditions remained the same. The resulting modified natural zeolite, free of (or low in) harmful heavy metals, had a higher arsenic content (7.73 mg / g in Implementation Method 5 compared to 0.48 mg / g in Implementation Method 1). Implementation Method 5's removal of harmful heavy metals was less effective than Implementation Method 1. This is mainly because, without ferrous ions to modify the natural zeolite solution, hydroxylamine hydrochloride alone could not dissolve the insoluble harmful heavy metal arsenic in the natural zeolite, thus maintaining a relatively high arsenic content.

[0054] Implementation Method 6:

[0055] This invention first modifies natural zeolite using an alkali (such as sodium hydroxide, potassium hydroxide, or ammonia). The sodium hydroxide concentration is 1M-2M, and the solid content of the natural zeolite solution is 1%-10%. The pH of the solution system is adjusted using sodium hydroxide solution and maintained between 11.5 and 13.5. The reaction is carried out at room temperature or with appropriate heating and stirring for 8-24 hours. Then, an appropriate amount of phosphoric acid is added to the solution to maintain the pH between 5.0 and 8.5, and the reaction is carried out at room temperature or with appropriate heating for 8-24 hours.

[0056] Take an appropriate amount of ferrous salt (Fe 2+ A solution of ferrous salt (0.1-2M) is prepared by dissolving it in hydrochloric acid, and hydroxylamine hydrochloride (NH₂OH·HCl) is added. The molar ratio of ferrous ions to hydroxylamine hydrochloride is 10:1-100:1. The modified natural zeolite solution is mixed with the ferrous salt and hydroxylamine hydrochloride, and the mass ratio of modified natural zeolite to ferrous ions in the mixed solution is 5:1-100:1. The pH of the solution is adjusted to 2.5-4 with saline or acetic acid, and the reaction is carried out at room temperature or by heating for 8-24 hours. Then, an appropriate amount of EDTA is added to the mixed solution. The modified natural zeolite and EDTA are reacted at a mass ratio of 10:1 to 200:1. The pH of the solution is adjusted to 1.0-4.0 using hydrochloric acid or acetic acid, and the ionic strength is adjusted using sodium chloride. The mixture is stirred and reacted at room temperature or with appropriate heating for 8-24 hours. The natural zeolite is then separated from the solution, for example, by allowing it to settle naturally for 6-24 hours, removing the supernatant, and then filtering, or by centrifuging and removing the supernatant. Water is then added and the mixture is repeatedly washed until the pH of the washing solution is neutral. The mixture is then allowed to settle naturally, filtered, and the supernatant is removed, or by centrifugation and removing the supernatant. After separating the natural zeolite from the solution, the resulting solution and washing solution are mixed with the solution containing the oxidant and stirred to react. An appropriate amount of alkali solution is added to precipitate harmful heavy metals in the solution, facilitating their separation and preventing environmental pollution.

[0057] Prepare a solution using an appropriate amount of the modified natural zeolite with a heavy metal removal content between 1% and 50%. Then, add appropriate amounts of calcium, iron, and zinc ions to the modified natural zeolite with harmful heavy metal removal. Finally, separate the modified natural zeolite from the solution, for example, by allowing it to settle naturally for 6-24 hours to remove the supernatant and then filtering, or by centrifuging to remove the supernatant. After that, repeatedly wash with water until the pH of the washing solution is neutral, then allow it to settle naturally to remove the supernatant and then filter or centrifuge to remove the supernatant. The resulting modified natural zeolite with no (or low) harmful heavy metals is dried at 110℃ and then activated at 350℃-550℃ to obtain activated natural zeolite with no (or low) harmful heavy metals.

[0058] The difference between Implementation Scheme 6 and Implementation Method 1 lies in that the alkali-modified natural zeolite is reacted for a period of time, followed by the addition of phosphoric acid and a further reaction time. The solution containing phosphate ions is not separated from the natural zeolite; hydroxylamine hydrochloride and ferrous salt are added directly to continue the reaction. In Implementation Method 6, the large amount of phosphate ions in the solution readily reacts with ferrous ions to form a precipitate, significantly affecting the modification of natural zeolite by ferrous ions and hindering the dissolution of the insoluble harmful heavy metal arsenic from the natural zeolite. Therefore, the modified arsenic-free (low) content obtained by Implementation Method 6 (6.15 mg / g) is higher than the arsenic content of Implementation Method 1 (0.48 mg / g).

[0059] Implementation Method 7:

[0060] This invention first modifies natural zeolite using an alkali (such as sodium hydroxide, potassium hydroxide, or ammonia). The sodium hydroxide concentration is 1M-2M, and the solid content of the natural zeolite solution is 1%-10%. The pH of the solution system is adjusted using sodium hydroxide solution and maintained between 11.5 and 13.5. The reaction is carried out at room temperature or with appropriate heating and stirring for 8-24 hours. An appropriate amount of phosphoric acid is added to the solution to maintain the pH between 5.0 and 8.5, and the reaction is carried out at room temperature or with appropriate heating for 8-24 hours. The modified natural zeolite is then separated from the solution, for example, by allowing it to settle naturally for 6-24 hours, removing the supernatant, and then filtering or centrifuging to remove the supernatant. Water is then added and the solution is repeatedly washed until the pH of the washing liquid is neutral. The solution is then allowed to settle naturally, filtered, or centrifuged. After the natural zeolite is separated from the solution, the solution and washing liquid are collected, and an appropriate amount of oxidant is added and stirred appropriately for later use. The oxidant can be one or more of hydrogen peroxide, sodium percarbonate, ozone, sodium hypochlorite, or potassium nitrate.

[0061] The obtained modified natural zeolite was dissolved in water to form a solution with a solid content of 1%-10%. An appropriate amount of ferrous salt (Fe) was then added. 2+A solution of ferrous salt (0.1-2M) is prepared by dissolving it in hydrochloric acid, and hydroxylamine hydrochloride (NH₂OH·HCl) is added. The molar ratio of ferrous ions to hydroxylamine hydrochloride is 10:1-100:1. The modified natural zeolite solution is mixed with the ferrous salt and hydroxylamine hydrochloride, and the mass ratio of modified natural zeolite to ferrous ions in the mixed solution is 5:1-100:1. The pH of the solution is adjusted to 2.5-4 with saline or acetic acid, and the reaction is carried out at room temperature or by heating for 8-24 hours. Then, an appropriate amount of EDTA is added to the mixed solution. The modified natural zeolite and EDTA are reacted at a mass ratio of 10:1 to 200:1. The pH of the solution is adjusted to 1.0-4.0 using hydrochloric acid or acetic acid, and the ionic strength is adjusted using sodium chloride. The mixture is stirred and reacted at room temperature or with appropriate heating for 8-24 hours. The natural zeolite is then separated from the solution, for example, by allowing it to settle naturally for 6-24 hours, removing the supernatant, and then filtering, or by centrifuging and removing the supernatant. Water is then added and the mixture is repeatedly washed until the pH of the washing solution is neutral. The mixture is then allowed to settle naturally, filtered, and the supernatant is removed, or by centrifugation and removing the supernatant. After separating the natural zeolite from the solution, the resulting solution and washing solution are mixed with the solution containing the oxidant and stirred to react. An appropriate amount of alkali solution is added to precipitate harmful heavy metals in the solution, facilitating their separation and preventing environmental pollution.

[0062] The modified natural zeolite is separated from the solution, for example, by allowing it to settle naturally for 6-24 hours to remove the supernatant and then filtering, or by centrifuging to remove the supernatant. Then, water is added and the solution is repeatedly washed until the pH of the washing solution is neutral. The supernatant is then removed by natural sedimentation and then filtered or centrifuged. The resulting modified natural zeolite free of (or low in) harmful heavy metals is dried at 110℃ and then activated at 350℃-550℃ to obtain activated natural zeolite free of (or low in) harmful heavy metals.

[0063] The difference between Implementation Method 7 and Implementation Method 1 is that the natural zeolite for removing harmful heavy metals was not modified with iron, calcium, and zinc ions. Compared with Implementation Method 1, the modified natural zeolite with no (or low) harmful heavy metals obtained by Implementation Method 7 is close to the removal of harmful heavy metals such as lead, arsenic, mercury, and cadmium in Implementation Method 1. However, in simulated gastric acid solution, the modified natural zeolite with no (or low) harmful heavy metals obtained by Implementation Method 7 has a certain adsorption of calcium, zinc, and iron ions. Oral ingestion may reduce the concentration of beneficial calcium, iron, and zinc ions in the human body.

[0064] Implementation Method 8:

[0065] This invention first modifies natural zeolite using an alkali (such as sodium hydroxide, potassium hydroxide, or ammonia). The natural zeolite solution has a solid content of 1%-10%. An appropriate amount of ammonia gas is introduced into the solution, or an appropriate amount of ammonia solution is added to adjust the pH of the solution system and maintain it between 11.5 and 13.5. The reaction is carried out at room temperature or with appropriate heating for 8-24 hours with stirring. An appropriate amount of phosphoric acid is added to the solution to maintain the pH between 5.0 and 8.5, and the reaction is carried out at room temperature or with appropriate heating for 8-24 hours. The modified natural zeolite is then separated from the solution, for example, by allowing it to settle naturally for 6-24 hours, removing the supernatant, and then filtering, or by centrifuging to remove the supernatant. Water is then added and the solution is repeatedly washed until the pH of the washing liquid is neutral. The solution is then allowed to settle naturally, filtered, or centrifuged. After the natural zeolite is separated from the solution, the solution and washing liquid are collected, and an appropriate amount of oxidant is added and stirred appropriately for later use. The oxidant can be one or more of hydrogen peroxide, sodium percarbonate, ozone, sodium hypochlorite, or potassium nitrate.

[0066] The obtained modified natural zeolite was dissolved in water to form a solution with a solid content of 1%-10%. An appropriate amount of ferrous salt (Fe) was then added. 2+ A solution of ferrous salt (0.1-2M) is prepared by dissolving it in hydrochloric acid, and hydroxylamine hydrochloride (NH₂OH·HCl) is added. The molar ratio of ferrous ions to hydroxylamine hydrochloride is 10:1-100:1. The modified natural zeolite solution is mixed with the ferrous salt and hydroxylamine hydrochloride, and the mass ratio of modified natural zeolite to ferrous ions in the mixed solution is 5:1-100:1. The pH of the solution is adjusted to 2.5-4 with saline or acetic acid, and the reaction is carried out at room temperature or by heating for 8-24 hours. Then, an appropriate amount of EDTA is added to the mixed solution. The modified natural zeolite and EDTA are reacted at a mass ratio of 10:1 to 200:1. The pH of the solution is adjusted to 1.0-4.0 using hydrochloric acid or acetic acid, and the ionic strength is adjusted using sodium chloride. The mixture is stirred and reacted at room temperature or with appropriate heating for 8-24 hours. The natural zeolite is then separated from the solution, for example, by allowing it to settle naturally for 6-24 hours, removing the supernatant, and then filtering, or by centrifuging and removing the supernatant. Water is then added and the mixture is repeatedly washed until the pH of the washing solution is neutral. The mixture is then allowed to settle naturally, filtered, and the supernatant is removed, or by centrifugation and removing the supernatant. After separating the natural zeolite from the solution, the resulting solution and washing solution are mixed with the solution containing the oxidant and stirred to react. An appropriate amount of alkali solution is added to precipitate harmful heavy metals in the solution, facilitating their separation and preventing environmental pollution.

[0067] Prepare a solution using an appropriate amount of the modified natural zeolite with a heavy metal removal content between 1% and 50%. Then, add appropriate amounts of calcium, iron, and zinc ions to the modified natural zeolite with harmful heavy metal removal. Finally, separate the modified natural zeolite from the solution, for example, by allowing it to settle naturally for 6-24 hours to remove the supernatant and then filtering, or by centrifuging to remove the supernatant. After that, repeatedly wash with water until the pH of the washing solution is neutral, then allow it to settle naturally to remove the supernatant and then filter or centrifuge to remove the supernatant. The resulting modified natural zeolite with no (or low) harmful heavy metals is dried at 110℃ and then activated at 350℃-550℃ to obtain activated natural zeolite with no (or low) harmful heavy metals.

[0068] The difference between Implementation Method 8 and Implementation Method 1 is that the alkaline solution used for modifying natural zeolite is ammonia gas or ammonia water. Other conditions are the same. The modified natural zeolite without (or with low) harmful heavy metals obtained by Implementation Method 8 has no significant difference in harmful heavy metals and performance compared with Implementation Method 1. This indicates that the key to removing harmful heavy metals such as arsenic and reducing aluminum leaching in alkaline-modified zeolite lies in the pH range of the solution.

[0069] Implementation Method 9:

[0070] This invention first modifies natural zeolite using an alkali (such as sodium hydroxide, potassium hydroxide, or ammonia). The sodium hydroxide concentration is 1M-2M, and the solid content of the natural zeolite solution is 1%-10%. The pH of the solution system is adjusted using sodium hydroxide solution and maintained between 11.5 and 13.5. The reaction is carried out at room temperature or with appropriate heating and stirring for 8-24 hours. An appropriate amount of phosphoric acid is added to the solution to maintain the pH between 5.0 and 8.5, and the reaction is carried out at room temperature or with appropriate heating for 8-24 hours. The modified natural zeolite is then separated from the solution, for example, by allowing it to settle naturally for 6-24 hours, removing the supernatant, and then filtering or centrifuging to remove the supernatant. Water is then added and the solution is repeatedly washed until the pH of the washing liquid is neutral. The solution is then allowed to settle naturally, filtered, or centrifuged. After the natural zeolite is separated from the solution, the solution and washing liquid are collected, and an appropriate amount of oxidant is added and stirred appropriately for later use. The oxidant can be one or more of hydrogen peroxide, sodium percarbonate, ozone, sodium hypochlorite, or potassium nitrate.

[0071] The obtained modified natural zeolite was dissolved in water to form a solution with a solid content of 1%-10%. An appropriate amount of ferrous salt (Fe) was then added. 2+A 0.1-2M solution of ferrous salt (NH₂OH·HCl) is prepared by dissolving it in hydrochloric acid, and hydroxylamine hydrochloride (NH₂OH·HCl) is added, with a molar ratio of ferrous ions to hydroxylamine hydrochloride of 10:1-100:1. The modified natural zeolite solution is mixed with the ferrous salt and hydroxylamine hydrochloride, with a mass ratio of modified natural zeolite to ferrous ions of 5:1-100:1 in the mixed solution. The pH of the solution is adjusted to 2.5-4 with saline or acetic acid, and the reaction is carried out at room temperature or by heating for 8-24 hours. Then, appropriate amounts of disodium EDTA and citric acid are added to the mixed solution to modify the ferrous salt. The mass ratio of natural zeolite to disodium EDTA and citric acid is 10:1:1-200:1:1. The pH of the solution is adjusted to 1.0-4.0 using hydrochloric acid or acetic acid, and the ionic strength is adjusted using sodium chloride. The mixture is stirred and reacted at room temperature or with appropriate heating for 8-24 hours. The natural zeolite is then separated from the solution, for example, by allowing it to settle naturally for 6-24 hours, removing the supernatant, and then filtering, or by centrifuging and removing the supernatant. Water is then added and repeatedly washed until the pH of the washing solution is neutral. This process is repeated by allowing it to settle naturally, filtering, removing the supernatant, and then filtering again, or by centrifuging and removing the supernatant. After separating the natural zeolite from the solution, the resulting solution and washing solution are mixed with the solution containing the oxidant and stirred to react. An appropriate amount of alkali solution is added to precipitate harmful heavy metals in the solution, facilitating their separation and preventing environmental pollution.

[0072] Prepare a solution using an appropriate amount of the modified natural zeolite with a heavy metal removal content between 1% and 50%. Then, add appropriate amounts of calcium, iron, and zinc ions to the modified natural zeolite with harmful heavy metal removal. Finally, separate the modified natural zeolite from the solution, for example, by allowing it to settle naturally for 6-24 hours to remove the supernatant and then filtering, or by centrifuging to remove the supernatant. After that, repeatedly wash with water until the pH of the washing solution is neutral, then allow it to settle naturally to remove the supernatant and then filter or centrifuge to remove the supernatant. The resulting modified natural zeolite with no (or low) harmful heavy metals is dried at 110℃ and then activated at 350℃-550℃ to obtain activated natural zeolite with no (or low) harmful heavy metals.

[0073] The difference between Implementation Method 9 and Implementation Method 1 is that different complexing agents or chelating agents are used. Under the same other conditions, the modified natural zeolite with no (low) harmful heavy metals obtained by Implementation Method 9 has no significant difference in harmful heavy metals and performance compared with Implementation Method 1, indicating that the combined use of one or more complexing agents or chelating agents can effectively remove other heavy metals from natural zeolite.

[0074] Implementation Method 10:

[0075] This invention first modifies natural zeolite using an alkali (such as sodium hydroxide, potassium hydroxide, or ammonia). The sodium hydroxide concentration is 1M-2M, and the solid content of the natural zeolite solution is 1%-10%. The pH of the solution system is adjusted using sodium hydroxide solution and maintained between 11.5 and 13.5. The reaction is carried out at room temperature or with appropriate heating and stirring for 8-24 hours. An appropriate amount of phosphoric acid is added to the solution to maintain the pH between 5.0 and 8.5, and the reaction is carried out at room temperature or with appropriate heating for 8-24 hours. The modified natural zeolite is then separated from the solution, for example, by allowing it to settle naturally for 6-24 hours, removing the supernatant, and then filtering or centrifuging to remove the supernatant. Water is then added and the solution is repeatedly washed until the pH of the washing liquid is neutral. The solution is then allowed to settle naturally, filtered, or centrifuged. After the natural zeolite is separated from the solution, the solution and washing liquid are collected, and an appropriate amount of oxidant is added and stirred appropriately for later use. The oxidant can be one or more of hydrogen peroxide, sodium percarbonate, ozone, sodium hypochlorite, or potassium nitrate.

[0076] The obtained modified natural zeolite was dissolved in water to form a solution with a solid content of 1%-10%. An appropriate amount of ferrous salt (Fe) was then added. 2+ A solution of ferrous salt (0.1-2M) was prepared by dissolving it in hydrochloric acid, and hydroxylamine hydrochloride (NH₂OH·HCl) was added, with a molar ratio of ferrous ions to hydroxylamine hydrochloride of 10:1-100:1. The modified natural zeolite solution was mixed with the ferrous salt and hydroxylamine hydrochloride, with a mass ratio of modified natural zeolite to ferrous ions of 5:1-100:1 in the mixed solution. The pH of the solution was adjusted to 2.5-4 with saline or acetic acid, and the reaction was carried out at room temperature or by heating for 8-24 hours. Then, appropriate amounts of NTA and HEDTA were added to the mixed solution to modify the ferrous salt. Natural zeolite is reacted with NTA and HEDTA in a mass ratio of 10:1:1 to 200:1:1. The pH of the solution is adjusted to 1.0-4.0 using hydrochloric acid or acetic acid, and the ionic strength is adjusted with sodium chloride. The reaction is carried out with stirring at room temperature or with appropriate heating for 8-24 hours. The natural zeolite is then separated from the solution, for example, by allowing it to settle naturally for 6-24 hours, removing the supernatant, and then filtering, or by centrifugation and removing the supernatant. The solution is then repeatedly washed with water until the pH of the washing solution is neutral, followed by natural sedimentation, filtration, and further filtration, or by centrifugation and removing the supernatant. After separation, the resulting solution and washings are mixed with the solution containing the oxidant and stirred. An appropriate amount of alkali is added to precipitate harmful heavy metals from the solution, facilitating their separation and preventing environmental pollution.

[0077] Prepare a solution using an appropriate amount of the modified natural zeolite with a heavy metal removal content between 1% and 50%. Then, add appropriate amounts of calcium, iron, and zinc ions to the modified natural zeolite with harmful heavy metal removal. Finally, separate the modified natural zeolite from the solution, for example, by allowing it to settle naturally for 6-24 hours to remove the supernatant and then filtering, or by centrifuging to remove the supernatant. After that, repeatedly wash with water until the pH of the washing solution is neutral, then allow it to settle naturally to remove the supernatant and then filter or centrifuge to remove the supernatant. The resulting modified natural zeolite with no (or low) harmful heavy metals is dried at 110℃ and then activated at 350℃-550℃ to obtain activated natural zeolite with no (or low) harmful heavy metals.

[0078] The difference between implementation method 10 and implementation method 1 is that the complexing agent or chelating agent is different, while other conditions are the same. The modified natural zeolite with no (low) harmful heavy metals obtained by implementation method 9 has no significant difference in harmful heavy metals and properties compared with implementation method 1, indicating that the combined use of different complexing agents or chelating agents can effectively remove other heavy metals from natural zeolite.

[0079] Implementation Method 11:

[0080] This invention first modifies natural zeolite using an alkali (such as sodium hydroxide, potassium hydroxide, or ammonia). The sodium hydroxide concentration is 1M-2M, and the solid content of the natural zeolite solution is 1%-10%. The pH of the solution system is adjusted using sodium hydroxide solution and maintained between 11.5 and 13.5. The reaction is carried out at room temperature or with appropriate heating and stirring for 8-24 hours. An appropriate amount of phosphoric acid is added to the solution to maintain the pH between 5.0 and 8.5, and the reaction is carried out at room temperature or with appropriate heating for 8-24 hours. The modified natural zeolite is then separated from the solution, for example, by allowing it to settle naturally for 6-24 hours, removing the supernatant, and then filtering or centrifuging to remove the supernatant. Water is then added and the solution is repeatedly washed until the pH of the washing liquid is neutral. The solution is then allowed to settle naturally, filtered, or centrifuged. After the natural zeolite is separated from the solution, the solution and washing liquid are collected, and an appropriate amount of oxidant is added and stirred appropriately for later use. The oxidant can be one or more of hydrogen peroxide, sodium percarbonate, ozone, sodium hypochlorite, or potassium nitrate.

[0081] The obtained modified natural zeolite was dissolved in water to form a solution with a solid content of 1%-10%. An appropriate amount of ferrous salt (Fe) was then added. 2+A solution of ferrous salt (0.1-2M) is prepared by dissolving it in hydrochloric acid, and hydroxylamine hydrochloride (NH₂OH·HCl) is added, with a molar ratio of ferrous ions to hydroxylamine hydrochloride of 10:1-100:1. The modified natural zeolite solution is mixed with the ferrous salt and hydroxylamine hydrochloride, with a mass ratio of modified natural zeolite to ferrous ions of 5:1-100:1 in the mixed solution. The pH of the solution is adjusted to 2.5-4 with saline or acetic acid, and the reaction is carried out at room temperature or by heating for 8-24 hours. Then, appropriate amounts of disodium EDTA and citric acid are added to the mixed solution to modify the natural zeolite. The mass ratio of zeolite to disodium EDTA and citric acid is 10:1:1-200:1:1. The pH of the solution is adjusted to 4.5-7.0 using hydrochloric acid, acetic acid, or alkaline solution, and the ionic strength is adjusted using sodium chloride. The reaction is carried out with stirring at room temperature or with appropriate heating for 8-24 hours. The natural zeolite is then separated from the solution, for example, by allowing it to settle naturally for 6-24 hours, removing the supernatant, and then filtering, or by centrifuging and removing the supernatant. Water is then added and repeatedly washed until the pH of the washing solution is neutral. The mixture is then allowed to settle naturally, filtered, and the supernatant removed, or by centrifugation and removing the supernatant. After separating the natural zeolite from the solution, the resulting solution and washing solution are mixed with the solution containing the oxidant and stirred to react. An appropriate amount of alkaline solution is added to precipitate harmful heavy metals in the solution, facilitating their separation and preventing environmental pollution.

[0082] Prepare a solution using an appropriate amount of the modified natural zeolite with a heavy metal removal content between 1% and 50%. Then, add appropriate amounts of calcium, iron, and zinc ions to the modified natural zeolite with harmful heavy metal removal. Finally, separate the modified natural zeolite from the solution, for example, by allowing it to settle naturally for 6-24 hours to remove the supernatant and then filtering, or by centrifuging to remove the supernatant. After that, repeatedly wash with water until the pH of the washing solution is neutral, then allow it to settle naturally to remove the supernatant and then filter or centrifuge to remove the supernatant. The resulting modified natural zeolite with no (or low) harmful heavy metals is dried at 110℃ and then activated at 350℃-550℃ to obtain activated natural zeolite with no (or low) harmful heavy metals.

[0083] The only difference between Method 11 and Method 9 is that the pH value of the solution system differs after the addition of the complexing or chelating agent. The pH range is adjusted from 1.0-4.0 in Method 9 to 4.5-7.0 in Method 11. The modified natural zeolite obtained through Method 11, which is free of (or low in) harmful heavy metals, contains higher levels of lead, mercury, and cadmium than that obtained through Methods 1, 9, and 10. This indicates that the removal of other heavy metals from natural zeolite is significantly affected by the solution pH.

[0084] Implementation Method 12:

[0085] This invention first modifies natural zeolite using an alkali (such as sodium hydroxide, potassium hydroxide, or ammonia). The sodium hydroxide concentration is 1M-2M, and the solid content of the natural zeolite solution is 1%-10%. The pH of the solution system is adjusted using sodium hydroxide solution and maintained between 11.5 and 13.5. The reaction is carried out at room temperature or with appropriate heating and stirring for 8-24 hours. An appropriate amount of phosphoric acid is added to the solution to maintain the pH between 5.0 and 8.5, and the reaction is carried out at room temperature or with appropriate heating for 8-24 hours. The modified natural zeolite is then separated from the solution, for example, by allowing it to settle naturally for 6-24 hours, removing the supernatant, and then filtering or centrifuging to remove the supernatant. Water is then added and the solution is repeatedly washed until the pH of the washing liquid is neutral. The solution is then allowed to settle naturally, filtered, or centrifuged. After the natural zeolite is separated from the solution, the solution and washing liquid are collected, and an appropriate amount of oxidant is added and stirred appropriately for later use. The oxidant can be one or more of hydrogen peroxide, sodium percarbonate, ozone, sodium hypochlorite, or potassium nitrate.

[0086] The obtained modified natural zeolite was dissolved in water to form a solution with a solid content of 1%-10%. An appropriate amount of ferrous salt (Fe) was then added. 2+ A solution of ferrous zeolite (0.1-2M) is prepared by dissolving it in hydrochloric acid and adding hydroxylamine hydrochloride (NH2OH.HCl), with a molar ratio of ferrous ions to hydroxylamine hydrochloride of 10:1-100:1. The modified natural zeolite solution is mixed with ferrous salt and hydroxylamine hydrochloride, with a mass ratio of modified natural zeolite to ferrous ions of 5:1-100:1 in the mixed solution. The pH of the solution is adjusted to 2.5-4 with saline or acetic acid, and the reaction is carried out at room temperature or by heating for 8-24 hours. The pH of the solution is then adjusted to 1.0-4.0 with hydrochloric acid or acetic acid, and the ionic strength of the solution is adjusted with sodium chloride. The reaction is carried out by stirring at room temperature or by appropriate heating for 8-24 hours. The natural zeolite is then separated from the solution, for example, by allowing it to settle naturally for 6-24 hours, removing the supernatant and then filtering, or by centrifuging and removing the supernatant. After that, water is added and the solution is repeatedly washed until the pH of the washing solution is neutral. Then, the solution is allowed to settle naturally, filtered to remove the supernatant and then filtered again, or by centrifuging and removing the supernatant. After separating the natural zeolite from the solution, the resulting solution and washing liquid are mixed and stirred with the solution containing the oxidant. An appropriate amount of alkali solution is added to precipitate the harmful heavy metals in the solution, making it easier to separate them from the solution and avoid polluting the environment with harmful heavy metals.

[0087] Prepare a solution using an appropriate amount of the modified natural zeolite with a heavy metal removal content between 1% and 50%. Then, add appropriate amounts of calcium, iron, and zinc ions to the modified natural zeolite with harmful heavy metal removal. Finally, separate the modified natural zeolite from the solution, for example, by allowing it to settle naturally for 6-24 hours to remove the supernatant and then filtering, or by centrifuging to remove the supernatant. After that, repeatedly wash with water until the pH of the washing solution is neutral, then allow it to settle naturally to remove the supernatant and then filter or centrifuge to remove the supernatant. The resulting modified natural zeolite with no (or low) harmful heavy metals is dried at 110℃ and then activated at 350℃-550℃ to obtain activated natural zeolite with no (or low) harmful heavy metals.

[0088] The significant difference between Method 12 and Method 9 is that no complexing or chelating agents were added; all other adjustments were the same. The modified natural zeolite obtained through Method 12, free of (or low in) harmful heavy metals, contained significantly higher levels of lead, mercury, and cadmium than that obtained through Methods 1, 8, 9, and 10. This indicates that complexing or chelating agents can significantly remove harmful heavy metals such as lead, mercury, and cadmium from natural zeolite.

[0089] For the sake of technical rigor, the experimental test data are shown in the table below:

[0090] Table 1. Detection results of harmful heavy metals in natural zeolite raw materials (GB5009)

[0091]

[0092] Table 2. Results of Hazardous Heavy Metal Detection in Modified and Activated Natural Zeolite (GB5009)

[0093]

[0094] Table 3 Performance Indicators of Zeolite Raw Materials

[0095]

[0096] Table 4 Performance Indicators of Modified Activated Zeolite

[0097]

[0098] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for manufacturing activated zeolite free of harmful heavy metals, characterized in that: The specific operating steps are as follows: S1: Select alkali-modified and unblocking natural zeolite, and prepare a solution with natural zeolite. The solid content of the prepared solution is 1%-50%. Use alkali to adjust the pH of the solution system to maintain it between 12.5-13.5 and stir. S2: While stirring the solution, add phosphoric acid to maintain the pH value of the solution between 5.0 and 8.5 for the reaction. After the reaction, wash repeatedly until the pH value of the washing solution is neutral. Then, separate the modified natural zeolite from the solution and add an oxidant to the solution collected after separation. S3: Take the modified natural zeolite obtained above and prepare a solution. The solid content of the modified natural zeolite in the solution is 1%-50%. Dissolve the ferrous salt in hydrochloric acid to prepare a solution. Then add hydroxylamine hydrochloride. Mix the modified natural zeolite solution with the ferrous salt, hydrochloric acid and hydroxylamine hydrochloride solution, and adjust the pH of the solution to 2.5-4 with acetic acid and react for a period of time. S4: Add a complexing agent to the mixed solution after step S3, adjust the pH of the solution to between 1.0 and 4.0 with acetic acid, stir and react for a period of time, then separate the modified natural zeolite from the solution, and then wash repeatedly until the pH of the washing solution is neutral and separate again. S5: After separating the modified natural zeolite from the solution in step S4, mix the resulting solution with the solution in step S2 where the oxidant was added and stir to react. Add alkali solution to separate the harmful heavy metal precipitate from the solution. S6: Prepare a solution of the above-mentioned modified natural zeolite with a solid content between 1% and 50%. Add calcium ions, iron ions, and zinc ions to the modified natural zeolite. Finally, separate the modified natural zeolite from the solution. Then, wash repeatedly until the pH of the washing solution is neutral and separate again. The obtained modified natural zeolite free of harmful heavy metals is dried at 110℃ and then activated at 350℃-550℃ to obtain activated natural zeolite free of harmful heavy metals.

2. The method for manufacturing activated zeolite free of harmful heavy metals according to claim 1, characterized in that: The alkali used in step S1 is sodium hydroxide, potassium hydroxide, or ammonia.

3. The method for manufacturing activated zeolite free of harmful heavy metals according to claim 1, characterized in that: The separation methods in steps S2 and S4 are either static sedimentation for 6-24 hours followed by filtration or centrifugal filtration.

4. The method for manufacturing activated zeolite free of harmful heavy metals according to claim 3, characterized in that: The oxidant in step S5 is one or more of hydrogen peroxide, sodium percarbonate, ozone, sodium hypochlorite, or potassium nitrate.

5. The method for manufacturing activated zeolite free of harmful heavy metals according to claim 4, characterized in that: In step S3, the molar ratio of ferrous ions to hydroxylamine hydrochloride is 10:1-100:1, and the mass ratio of modified natural zeolite to ferrous ions in the modified natural zeolite solution and the mixture of ferrous salt and hydroxylamine hydrochloride is 5:1-100:

1.

6. The method for manufacturing activated zeolite free of harmful heavy metals according to claim 4, characterized in that: The complexing agent in S4 is a chelating agent, and the mass ratio of modified natural zeolite to chelating agent is 10:1-200:

1.

7. A method for manufacturing activated zeolite free of harmful heavy metals according to claim 6, characterized in that: The chelating agents include citric acid, ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid and diethyltriacetic acid, organic acids and phytic acid.

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