A method for preparing and applying a lauryl diphosphonic acid / mesoporous hydroxyapatite organic-inorganic hybrid composite material.

Abstract

This invention discloses a preparation method and application of a lauryl bisphosphonate / mesoporous hydroxyapatite organic-inorganic hybrid composite material, belonging to the field of landfill leachate treatment technology. A solution of dipotassium hydrogen phosphate is prepared and then added dropwise to a mixed solution of calcium chloride and lauryl bisphosphonate. The pH of the solution is adjusted with alkali, washed with water, and then heated and dried to obtain the lauryl bisphosphonate / mesoporous hydroxyapatite organic-inorganic hybrid composite material. This composite material exhibits strong complexing ability with various heavy metal ions, and its adsorption performance is minimally affected by soluble organic acids in landfill leachate, ensuring long-term locking of heavy metal ions and avoiding secondary pollution caused by the re-dissolution of heavy metals. It has strong market potential and application value in the fields of landfill leachate treatment and environmental remediation.

Description

Technical Field

[0001] This invention relates to a method for preparing and applying a lauryl diphosphonic acid / mesoporous hydroxyapatite organic-inorganic hybrid composite material, belonging to the field of landfill leachate treatment technology. Background Technology

[0002] Leachate is generated during the process of landfilling or disposal (sanitary landfill, incineration, and temporary storage). In my country, approximately 5.0 × 10⁻⁶ tons of leachate are generated annually. 7 Landfill leachate is generated. Landfill leachate has a complex composition, containing a wide variety of metal ions, particularly Cd, Cr, Pb, Zn, Cu, and Ni. The content of Zn, Pb, and Cu can reach hundreds of milligrams per liter, while the content of cadmium and chromium can reach tens of milligrams per liter. GB 16889-2008 clearly stipulates the discharge concentrations for landfill leachate, specifying 0.1 mg / L for total lead and total chromium, 0.01 mg / L for total cadmium, and 0.5 mg / L for total copper and zinc. If heavy metals in wastewater and landfill leachate are not properly treated, they can enter groundwater and soil environments, causing toxicity and inhibition of microorganisms, affecting biochemical processes, threatening the ecological environment, and accumulating in plants, thus harming human health. For example, lead is a metabolic toxin, enzyme inhibitor, and carcinogen that can cause allergic reactions, intellectual disability, and brain damage. Cadmium harms the kidneys and liver; cadmium accumulation in the liver can cause stem cell swelling, cadmium poisoning leads to bone atrophy and softening, cardiovascular disease, endocrine disorders, and severely damages the human immune and nervous systems—and these changes are irreversible. Chromium compounds can cause respiratory and gastrointestinal diseases, and in more severe cases, can cause cancers of the lungs, digestive tract, and bronchi. Excessive zinc intake can cause zinc poisoning, resulting in vomiting, diarrhea, intestinal dysfunction, gastrointestinal necrosis, and ulcers; in severe cases, gastric perforation can lead to peritonitis, shock, and death. Furthermore, if heavy metal ions are not removed during landfill leachate treatment, it will also affect the efficiency of biological treatment in removing organic pollutants. Therefore, the treatment of heavy metal pollutants in landfill leachate is extremely important and necessary.

[0003] Currently, the main methods for treating heavy metal ions in landfill leachate include: phytoremediation, biological methods, coagulation + chemical precipitation, membrane separation technology, ion exchange, electrodialysis, and adsorption. Among these, adsorption is widely used due to its simplicity, convenience, low cost, and good removal efficiency for heavy metals in landfill leachate. The adsorbents used for heavy metal ion treatment currently include light calcium carbonate, ochre, wood ash, bentonite, fly ash, and hydroxyapatite. These unmodified adsorbents have poor adsorption effects on heavy metal ions and cannot meet the requirements for heavy metal removal from landfill leachate. In contrast, activated carbon has a better adsorption effect on heavy metal ions, but it suffers from drawbacks such as high cost, difficult and expensive regeneration, and high operating costs for regeneration equipment. More importantly, the various soluble organic substances present in landfill leachate can also affect the adsorption efficiency of these adsorbents for heavy metal ions. Therefore, finding effective adsorbents that can effectively adsorb multiple metals while minimizing the impact of soluble organic matter on heavy metal adsorption, thereby reducing the treatment cost of heavy metals in landfill leachate and improving the removal efficiency of heavy metals, has become an urgent problem to be solved in landfill leachate treatment.

[0004] In recent years, hydroxyapatite (HAP) has become a hot topic in the research of heavy metal adsorbents due to its ion exchange properties, good biocompatibility, and environmental friendliness. HAP is a natural mineralization of calcium apatite, and its crystal lattice contains two Ca atoms at different positions. 2+ Because its valence bond and radius differ, it exhibits good compatibility with divalent metal cations of different radii and is easily absorbed by Cu. 2+ Zn 2+ Cd 2+ Pb 2+ HAP (Heavy Acid Adsorbent) undergoes ion exchange with heavy metal ions, thus exhibiting good removal effects for various heavy metals and being environmentally friendly, making it a novel environmental functional material. However, it suffers from drawbacks such as small specific surface area, low adsorption capacity, and slow adsorption rate. Therefore, functional modification of HAP through surface modification or doping to transform it into an excellent and efficient heavy metal adsorbent is crucial for its promising application in the treatment of heavy metal pollution in landfill leachate.

[0005] Currently, both domestically and internationally, most methods utilize organic polymers such as polyethylene glycol (PEG), polyvinyl alcohol, polyurethane, polyacrylonitrile, stearic acid, polyacrylamide (PAM), polyacrylic acid (PAA), chitosan, and xanthan gum as modifiers to modify HAP into nanofibers. This reduces the crystallinity of HAP, thereby increasing the specific surface area and improving the adsorption performance of HAP composites for heavy metals. However, these modification processes are complex and costly. Furthermore, the adsorption performance of the modified composites is significantly affected by soluble organic compounds such as humic acid and fulvic acid, which are heavy metal complexing agents. The adsorption stability for heavy metal ions is poor, posing a risk of heavy metal re-leaching. Therefore, these methods are unsuitable for treating heavy metal pollutants in landfill leachate with complex compositions and high soluble organic content.

[0006] In summary, the search for highly effective adsorbents that exhibit excellent adsorption performance for various heavy metal pollutants while minimizing the impact of soluble organic matter on heavy metal adsorption, thereby reducing the treatment cost of heavy metals in landfill leachate, improving the removal efficiency of heavy metals, enhancing the long-term locking and solidification effect of heavy metals, and reducing the environmental risk of re-pollution, has become an urgent problem to be solved in landfill leachate treatment. Summary of the Invention

[0007] Given the complex composition of landfill leachate, the diverse types of heavy metal ions, and the fact that soluble organic matter in the leachate can affect the removal of heavy metal ions, the present invention aims to provide a method for preparing a lauryl bisphosphonate / mesoporous hydroxyapatite organic-inorganic hybrid composite material and its application in landfill leachate treatment. This method uses dipotassium hydrogen phosphate, lauryl bisphosphonate, and calcium chloride as raw materials, combining a template method and an aqueous phase chemical precipitation method to prepare the lauryl bisphosphonate / mesoporous hydroxyapatite organic-inorganic hybrid composite material. This composite material exhibits excellent adsorption effects on heavy metal ions such as zinc, copper, and cadmium ions in landfill leachate, and the influence of organic acids such as humic acid and fulvic acid on the adsorption performance is relatively small, achieving long-term locking of heavy metal pollutants in landfill leachate and avoiding secondary pollution caused by the re-dissolution of heavy metals.

[0008] Specifically, the present invention first provides a method for preparing a lauryl diphosphonic acid / mesoporous hydroxyapatite organic-inorganic hybrid composite material, the method comprising the following steps:

[0009] Prepare a mixed solution of calcium chloride and lauryl bisphosphonic acid, as well as a dipotassium hydrogen phosphate solution. The molar ratio of inorganic phosphorus to organic phosphorus in dipotassium hydrogen phosphate and lauryl bisphosphonic acid is 4:0.3–2:3, and the Ca / P molar ratio is 1.2–1.7. Add the dipotassium hydrogen phosphate solution to the mixed solution of calcium chloride and lauryl bisphosphonic acid, adjust the pH of the mixture to 9.0–11, react for a period of time, and then age for a period of time. After solid-liquid separation, washing, and drying, the lauryl bisphosphonic acid / mesoporous hydroxyapatite organic-inorganic hybrid composite material can be obtained.

[0010] Preferably, the molar ratio of inorganic phosphorus to organic phosphorus in dipotassium hydrogen phosphate and lauryl diphosphonic acid is 3.95:0.6 to 2.6:2.2.

[0011] Preferably, the Ca / P molar ratio is 1.4 to 1.67.

[0012] Preferably, the dipotassium hydrogen phosphate solution is added to the mixed solution of calcium chloride and lauryl diphosphonic acid by dropwise addition.

[0013] Preferably, the reaction pH is controlled between 9.5 and 10.5.

[0014] Preferably, 5% to 30 wt% potassium hydroxide or sodium hydroxide is selected to adjust the pH of the mixture; more preferably, the concentration of potassium hydroxide or sodium hydroxide is 10 to 15 wt%.

[0015] Preferably, the reaction time is 60 min to 300 min, which can be 60 min, 120 min, 180 min, or 240 min; more preferably, it is 120 min to 180 min.

[0016] Preferably, the reaction temperature is 30–80°C, which can be 30°C, 40°C, 50°C, or 60°C; more preferably, it is 40–60°C.

[0017] Preferably, the aging time is 2 to 8 hours, which can be 2 hours, 4 hours, or 6 hours; more preferably, it is 4 hours to 6 hours.

[0018] Preferably, the aging is carried out at an ambient temperature, which can be 5 to 40°C, and more preferably 10 to 30°C.

[0019] Preferably, the solid-liquid separation can be performed by centrifugation or filtration.

[0020] Preferably, the washing process involves several water washes.

[0021] Preferably, the drying is carried out in an oven at 60–80°C.

[0022] The present invention also provides a lauryl diphosphonic acid / mesoporous hydroxyapatite organic-inorganic hybrid composite material prepared by the above preparation method.

[0023] The present invention also provides a method for treating wastewater containing heavy metal ions, wherein the method uses the above-mentioned lauryl diphosphonic acid / mesoporous hydroxyapatite organic-inorganic hybrid composite material as an adsorbent.

[0024] The present invention also provides a method for treating landfill leachate, wherein the method uses the above-mentioned lauryl diphosphonic acid / mesoporous hydroxyapatite organic-inorganic hybrid composite material as an adsorbent.

[0025] The present invention also provides a heavy metal ion adsorbent comprising the above-mentioned lauryl diphosphonic acid / mesoporous hydroxyapatite organic-inorganic hybrid composite material.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0027] 1. Compared with other composite materials, lauryl diphosphonic acid / mesoporous hydroxyapatite organic-inorganic hybrid composite materials are inexpensive to prepare, readily available, have almost no side effects on the environment, and are simple and convenient to manufacture.

[0028] 2. The prepared composite material has stable physicochemical properties and can be stored for a long time.

[0029] 3. Its ability to remove various heavy metal ions from landfill leachate far exceeds that of other materials, and it has great application prospects and market potential.

[0030] 4. It has a strong complexing ability with a variety of heavy metal ions, and its adsorption performance is minimally affected by soluble organic acids in landfill leachate, ensuring long-term locking of heavy metal ions and avoiding secondary pollution caused by the re-dissolution of heavy metals. Attached Figure Description

[0031] Figure 1 The cell structure of hydroxyapatite (a) and the molecular structure of lauryl diphosphonic acid (b).

[0032] Figure 2 The frontier molecular orbitals of lauryl diphosphonate, of which (a) the highest occupied orbital HOMO and (b) the lowest empty orbital LUMO.

[0033] Figure 3 FTIR (a), XRD (b), and BET (c) of lauryl bisphosphonate (LA), hydroxyapatite (HAP), and the lauryl bisphosphonate / hydroxyapatite mesoporous composite material (LA-HAP) prepared in Example 3.

[0034] Figure 4The adsorption properties of lauryl bisphosphonate / mesoporous hydroxyapatite composite material prepared in Example 3 for four metal ions, where (a) is Zn 2+ Cu 2+ and Cd 2+ (b) is Pb 2+ .

[0035] Figure 5 The effect of soluble organic acids on adsorption performance (a) and the desorption rates of four metal ions (b). Detailed Implementation

[0036] The present invention will be described in detail below through embodiments. However, the purpose and use of these examples are only for illustrating the present invention and do not constitute any limitation on the actual protection scope of the present invention, nor are they intended to limit the protection scope of the present invention to these examples.

[0037] Adsorption Experiment Measurement Method: The adsorption performance of lauryl bisphosphonate-modified hydroxyapatite for heavy metal ions was evaluated using a batch adsorption experiment. The specific procedure is as follows: Accurately weigh 20 mg of lauryl bisphosphonate-modified hydroxyapatite composite material, add 50 mL of a solution containing heavy metal ions (Pb). 2+ The initial concentration of the adsorbent was 1000 mg / L, and the initial concentrations of the other three metal ions were 250 mg / L. The adsorbent was reacted in an air bath shaker (temperature 25℃, 200 r / min) for 240 min to ensure that the adsorption reached equilibrium. After the experiment, the supernatant was filtered using a disposable syringe and a 0.45 μm hydrophilic nylon filter. The residual concentration of metal ions in the solution was determined using a WA2081 atomic absorption spectrophotometer. The adsorption capacity q of the adsorbent for heavy metal pollutants was calculated according to the following formula (1). e :

[0038]

[0039] Where, q e —Equilibrium adsorption capacity (mg / g)

[0040] m — Amount of adsorbent used (mg)

[0041] V – Volume of the adsorption solution (mL)

[0042] C0 — Initial concentration of heavy metal ions (mg / L)

[0043] C e —Final detection concentration of heavy metal ions (mg / L)

[0044] Experiment on the effects of humic acid and fulvic acid: Accurately weigh 20 mg of lauryl bisphosphonate modified hydroxyapatite composite material and add it to 50 mL of a mixed aqueous solution containing heavy metal ions and 30 mg / L humic acid or fulvic acid (Pb). 2+ The initial concentration of the adsorbent was 1000 mg / L, and the initial concentrations of the other three metal ions were 250 mg / L. The mixture was reacted in an air bath shaker (temperature 25℃, 200 r / min) for 240 min to ensure that the adsorption reached equilibrium. After the experiment, the supernatant was filtered using a disposable syringe and a 0.45 μm hydrophilic nylon filter. The residual concentration of metal ions Ce in the solution was determined using a WA2081 atomic absorption spectrophotometer, and the adsorption capacity q of the adsorbent for heavy metal pollutants was calculated according to formula (1). e .

[0045] Desorption experiment of heavy metal ions: Accurately weigh 20 mg of lauryl bisphosphonic acid modified hydroxyapatite composite material, and mix it with 50 mL of a solution containing heavy metal ions (Pb). 2+ An aqueous solution containing 1000 mg / L of heavy metal ions and 250 mg / L of the other three metal ions was mixed and reacted in an air bath shaker (25℃, 200 r / min) for 6 h to ensure adsorption equilibrium. The supernatant and solid adsorbent were then separated using a vacuum filter, and the concentration of heavy metal ions in the supernatant was measured. Simultaneously, the adsorbed lauryl bisphosphonate-modified hydroxyapatite composite material was added to a 0.1 mol / L NaNO3 solution and stirred in a magnetic stirrer for desorption. Desorption was carried out for 12 hours to ensure sufficient equilibrium, and then the supernatant was filtered through a 0.45 μm hydrophilic nylon filter. The concentration of heavy metal ions in the supernatant was measured again. The desorption rate of heavy metal ions was defined as the ratio of the capacity of desorbed heavy metal ions to the capacity of adsorbed heavy metal ions.

[0046] Example 1

[0047] 5g of calcium chloride and 0.7352g of lauryl bisphosphonic acid were dissolved in water to obtain a mixed solution of calcium chloride and lauryl bisphosphonic acid. Then, 4.865g of dipotassium hydrogen phosphate was weighed and dissolved in water to prepare a solution with a Ca / P (inorganic phosphorus + organic phosphorus) molar ratio of 1.4 and an inorganic phosphorus:organic phosphorus (molar ratio) of 3.95:0.6. The dipotassium hydrogen phosphate aqueous solution was added dropwise to the mixed solution of calcium chloride and lauryl bisphosphonic acid, heated to 30°C in a water bath, and the pH was adjusted to 9.0 with 10wt% potassium hydroxide aqueous solution. The mixture was stirred for 60 min, then aged for another 2 hours. The solid product was then obtained by filtration, washed three times with water, and dried overnight at 80°C in a drying oven to obtain a lauryl bisphosphonic acid / mesoporous hydroxyapatite organic-inorganic hybrid composite material.

[0048] The obtained product can adsorb lead ions up to 1200 mg / g, copper ions up to 150 mg / g, zinc ions up to 245 mg / g, and cadmium ions up to 320 mg / g, demonstrating excellent adsorption performance.

[0049] Example 2

[0050] 5g of calcium chloride and 1.585g of lauryl bisphosphonic acid were dissolved in water to obtain a mixed solution of calcium chloride and lauryl bisphosphonic acid. Then, 3.467g of dipotassium hydrogen phosphate was weighed and dissolved in water to prepare a solution with a Ca / P (inorganic phosphorus + organic phosphorus) molar ratio of 1.55 and an inorganic phosphorus:organic phosphorus (molar ratio) of 3.5:1.6. The dipotassium hydrogen phosphate aqueous solution was added dropwise to the mixed solution of calcium chloride and lauryl bisphosphonic acid, heated to 40°C in a water bath, and the pH was adjusted to 9.5 with 10% potassium hydroxide aqueous solution. The mixture was stirred for 120 min, and then aged for another 4 hours. The filtered solid product was washed three times with water and dried overnight at 80°C in a drying oven to obtain a lauryl bisphosphonic acid / mesoporous hydroxyapatite organic-inorganic hybrid composite material.

[0051] The obtained product can adsorb lead ions up to 1600 mg / g, copper ions up to 159 mg / g, zinc ions up to 292 mg / g, and cadmium ions up to 363 mg / g, demonstrating excellent adsorption performance.

[0052] Example 3

[0053] 5g of calcium chloride and 1.866g of lauryl bisphosphonic acid were dissolved in water to obtain a mixed solution of calcium chloride and lauryl bisphosphonic acid. Then, 2.816g of dipotassium hydrogen phosphate was weighed and dissolved in water to prepare a solution with a Ca / P (inorganic phosphorus + organic phosphorus) molar ratio of 1.67 and an inorganic phosphorus:organic phosphorus (molar ratio) of 3.0:2.0. The dipotassium hydrogen phosphate aqueous solution was added dropwise to the mixed solution of calcium chloride and lauryl bisphosphonic acid, heated to 50°C in a water bath, and the pH was adjusted to 10.5 with 10% potassium hydroxide aqueous solution. The mixture was stirred for 180 min, and then aged for 6 h. The filtered solid product was washed three times with water and dried overnight at 80°C in a drying oven to obtain a lauryl bisphosphonic acid / mesoporous hydroxyapatite organic-inorganic hybrid composite material.

[0054] The obtained product exhibits adsorption capacities of 2543 mg / g, 329 mg / g, 350 mg / g, and 477 mg / g for lead, copper, zinc, and cadmium ions, respectively, demonstrating excellent adsorption performance. (See attached image) Figure 4 Meanwhile, the presence of humic acid and fulvic acid in the solution has little effect on the removal of metal ions (see appendix). Figure 5 a) Desorption experiment (attached) Figure 5b)) indicates that the lauryl diphosphonic acid / mesoporous hydroxyapatite organic-inorganic hybrid composite material has very low desorption of heavy metal ions and a long-term locking effect on heavy metal ions, which can effectively avoid secondary pollution caused by the re-dissolution of heavy metal ions.

[0055] Example 4

[0056] 5g of calcium chloride and 2.333g of lauryl bisphosphonic acid were dissolved in water to obtain a mixed solution of calcium chloride and lauryl bisphosphonic acid. Then, 2.346g of dipotassium hydrogen phosphate was weighed and dissolved in water to prepare a solution with a Ca / P (inorganic phosphorus + organic phosphorus) molar ratio of 1.67 and an inorganic phosphorus:organic phosphorus (molar ratio) of 2.5:2.5. The dipotassium hydrogen phosphate aqueous solution was added dropwise to the mixed solution of calcium chloride and lauryl bisphosphonic acid, heated to 60℃ in a water bath, and the pH was adjusted to 11 with 10% potassium hydroxide aqueous solution. The mixture was stirred for 240 min, and then aged for another 4 h. The filtered solid product was washed three times with water and dried overnight at 80℃ in a drying oven to obtain a lauryl bisphosphonic acid / mesoporous hydroxyapatite organic-inorganic hybrid composite material. The obtained product has adsorption capacities of 1893 mg / g, 254 mg / g, 271 mg / g and 406 mg / g for lead ions, copper ions, zinc ions and cadmium ions respectively, showing excellent adsorption performance.

[0057] Figure 1 The molecular structure of hydroxyapatite (a) and the optimized lauryl diphosphonic acid (b) are shown.

[0058] Figure 2 The frontier molecular orbitals of lauryl bisphosphonate show that the two phosphonic acid groups in the lauryl bisphosphonate molecule contain highly electronegative oxygen atoms that can provide electrons.

[0059] Figure 3 The figure shows the characterization of the lauryl bisphosphonate / mesoporous hydroxyapatite composite material prepared in Example 3. As can be seen from the figure, lauryl bisphosphonate, as a template agent and modifier, can flexibly control the morphology of the prepared hydroxyapatite. The composite material exhibits an amorphous structure (XRD) and is a mesoporous material (BET).

[0060] Figure 4 The figures show the adsorption performance of the lauryl bisphosphonate / mesoporous hydroxyapatite composite material prepared in Example 3 for four heavy metal ions. As can be seen from the figures, the composite material exhibits excellent adsorption effects for all four heavy metal ions.

[0061] Figure 5a represents the experimental results showing the effect of humic acid and fulvic acid concentrations of 30 mg / L on adsorption performance. This indicates that humic acid and fulvic acid have minimal impact on the performance of the composite material. Therefore, the lauryl diphosphonic acid / mesoporous hydroxyapatite composite material prepared in Example 3 of this invention is not affected by soluble organic acids when used to treat heavy metal ions in landfill leachate. When the composite materials prepared in the other examples were used in humic acid and fulvic acid interference experiments, it was found that the adsorption capacity of the composite material of this invention for each metal ion still maintained more than 95% of the original adsorption capacity (see Table 1).

[0062] Table 1. Adsorption performance of the adsorbents in Examples 1, 2, and 4 of this invention for heavy metal ions in the presence of 30 mg / L humic acid and fulvic acid.

[0063]

[0064] Figure 5 b represents the desorption experiment results of heavy metal ions. It can be seen that when the lauryl bisphosphonate / mesoporous hydroxyapatite composite material prepared in Example 3 of this invention is used to treat heavy metal ions in landfill leachate, the lauryl bisphosphonate can form a stable complex with the heavy metal ions, effectively locking the heavy metal ions for a long time and preventing secondary pollution caused by the re-dissolution of heavy metal ions. When the composite materials prepared in the other examples were subjected to desorption experiments, it was found that the desorption rate of each metal ion by the composite material of this invention was less than 5% (see Table 2). Therefore, the composite material of this invention can achieve stable adsorption of heavy metal ions, thereby effectively locking the heavy metal ions for a long time.

[0065] Table 2 Desorption rates of heavy metal ions (adsorbent materials of Examples 1, 2 and 4 of this invention)

[0066]

[0067] Table 3 compares the adsorption performance of the organic-inorganic hybrid composite prepared in this invention with that of various adsorbent materials reported in the literature for various heavy metal ions. It can be seen from the table that the lauryl diphosphonic acid / mesoporous hydroxyapatite composite material prepared in this invention has a much higher adsorption performance for various heavy metal ions than other adsorbent materials. It has a strong advantage in the field of landfill leachate treatment and has broad market application prospects.

[0068] Table 3 Comparison of adsorption performance of various adsorbent materials for lead and copper ions

[0069]

[0070] References:

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[0080]

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[0081]

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[0083]

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[0084] Comparative Example 1

[0085] 5g of calcium chloride and 3.11g of lauryl bisphosphonic acid were dissolved in water to obtain a mixed solution of calcium chloride and lauryl bisphosphonic acid. Then, 1.564g of dipotassium hydrogen phosphate was weighed and dissolved in water to prepare a solution with a Ca / P (inorganic phosphorus + organic phosphorus) molar ratio of 1.67 and an inorganic phosphorus:organic phosphorus (molar ratio) of 2.0:4.0. The dipotassium hydrogen phosphate aqueous solution was added dropwise to the mixed solution of calcium chloride and lauryl bisphosphonic acid, heated to 60℃ in a water bath, and the pH was adjusted to 11 with 10% potassium hydroxide aqueous solution. The mixture was stirred for 240 min, and then aged for another 4 h. The filtered solid product was washed three times with water and dried overnight at 80℃ in a drying oven to obtain a lauryl bisphosphonic acid / mesoporous hydroxyapatite organic-inorganic hybrid composite material.

[0086] The obtained product exhibited adsorption capacities of 596 mg / g for lead ions, 65 mg / g for copper ions, 81 mg / g for zinc ions, and 88 mg / g for cadmium ions, demonstrating excellent adsorption performance. Compared with Examples 1-4, it is evident that the ratio of inorganic phosphorus to organophosphorus has a significant impact on the performance of the modified composite material.

[0087] Comparative Example 2

[0088] Dissolve 5g of calcium chloride and 2.597g of lauryl diphosphonic acid in water to obtain a mixed solution of calcium chloride and lauryl diphosphonic acid. Then weigh 3.919g of dipotassium hydrogen phosphate and dissolve it in water to make the Ca / P (inorganic phosphorus + organic phosphorus) molar ratio of the prepared solution 1.2, and the inorganic phosphorus:organic phosphorus (molar ratio) = 3.0:2.0. Potassium hydrogen phosphate aqueous solution was added dropwise to a mixed solution of calcium chloride and lauryl bisphosphonic acid. The mixture was heated to 50°C in a water bath, and the pH was adjusted to 10.5 with 10% potassium hydroxide aqueous solution. The mixture was stirred for 180 min, and then aged for another 6 h. The filtered solid product was washed three times with water and dried overnight at 80°C in a drying oven to obtain the lauryl bisphosphonic acid / mesoporous hydroxyapatite organic-inorganic hybrid composite material.

[0089] The adsorption capacities of the obtained products for lead ions, copper ions, zinc ions, and cadmium ions were 867 mg / g, 112 mg / g, 189 mg / g, and 214 mg / g, respectively. Compared with Examples 1-4, it can be seen that the adsorption performance of the calcium-deficient modified composite material with a low Ca / P molar ratio is significantly lower than that of the modified composite material with a Ca / P molar ratio of 1.4–1.67.

[0090] Comparative Example 3

[0091] 5g of calcium chloride and 3.245g of aminotriacetic acid were dissolved in water, and 4.693g of dipotassium hydrogen phosphate was dissolved in water to prepare a solution with a Ca / P molar ratio of 1.67. The dipotassium hydrogen phosphate aqueous solution was added dropwise to the mixed solution of calcium chloride and aminotriacetic acid, heated to 50°C in a water bath, and the pH was adjusted to 10.5 with a 10% potassium hydroxide aqueous solution. The mixture was stirred for 180 min, then aged for another 6 h. The filtered solid product was washed three times with water and dried overnight at 80°C in a drying oven to obtain the aminotriacetic acid-modified hydroxyapatite composite material.

[0092] The adsorption capacities of the obtained products for lead, copper, zinc, and cadmium ions were 942 mg / g, 95 mg / g, 109 mg / g, and 143 mg / g, respectively. Although aminotriacetic acid is also a heavy metal complexing agent, its adsorption performance for heavy metal ions is much lower than that in Examples 1-4 of this invention, indicating that the organic-inorganic hybrid hydroxyapatite composite material prepared by using lauryl diphosphonic acid as a modifier has greater advantages as an adsorbent for multiple heavy metal ions.

[0093] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for preparing lauryl alcohol diphosphonic acid / mesoporous hydroxyapatite organic-inorganic hybrid composite material, characterized by, The method comprises the following steps: The method comprises the following steps:

2. The production method according to claim 1, characterized by, The molar ratio of the dibasic potassium phosphate and the inorganic phosphorus and organic phosphorus in the lauryl alcohol diphosphonic acid is 3.95:0.6-2.6:2.2; and the molar ratio of Ca / P is 1.4-1.

67.

3. The preparation method according to claim 1, characterized in that, The reaction pH is controlled at 9.5-10.

5.

4. The production method according to claim 1, characterized by, The pH of the mixture is adjusted by 5%-30wt% potassium hydroxide or sodium hydroxide.

5. The preparation method according to claim 4, characterized in that, The concentration of the potassium hydroxide or sodium hydroxide is 10-15wt%.

6. The method of claim 1, wherein, The reaction time is 60 min to 300 min; the reaction temperature is 30 to 80 o C.

7. The production method according to claim 6, characterized by The reaction time is 120 min-180 min.

8. The production method according to claim 6, characterized by, The reaction temperature is 40-60 o C.

9. The method of any one of claims 1 to 8, wherein the method further comprises the step of: The aging time is 2-8 h, and the aging is carried out at an ambient temperature of 5-40℃.

10. The lauryl alcohol diphosphonic acid / mesoporous hydroxyapatite organic-inorganic hybrid composite material prepared by the preparation method according to any one of claims 1-9.

11. A method of treating wastewater containing heavy metal ions, characterized by, The method uses the lauryl alcohol diphosphonic acid / mesoporous hydroxyapatite organic-inorganic hybrid composite material according to claim 10 as an adsorbent.

12. A method of treating landfill leachate, characterized by, The method uses the lauryl alcohol diphosphonic acid / mesoporous hydroxyapatite organic-inorganic hybrid composite material according to claim 10 as an adsorbent.

13. A heavy metal ion adsorbent, characterized by, The heavy metal ion adsorbent comprises the lauryl alcohol diphosphonic acid / mesoporous hydroxyapatite organic-inorganic hybrid composite material according to claim 10.

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