阅读说明：本技术 一种铁掺杂羟基磷灰石/桑树杆生物炭的制备方法及其应用 (Preparation method and application of iron-doped hydroxyapatite/mulberry tree stalk biochar ) 是由 梁美娜 李净溪 王敦球 芦琳 曹海燕 阮麟乔 于 2021-08-16 设计创作，主要内容包括：本发明公开一种铁掺杂羟基磷灰石/桑树杆生物炭的制备方法及其应用。先将桑树杆磨碎、炭化得桑树杆生物炭粉末；按照摩尔比(Ca+Fe)/P＝1.67,在烧杯中加入硝酸钙溶液和四水合氯化亚铁溶液,在混合溶液中加入桑树杆生物炭,加入磷酸氢二铵溶液,在搅拌下加入氨水；过滤、洗涤、干燥、过筛,得铁掺杂羟基磷灰石/桑树杆生物炭。本发明易操作,成本低；所得材料应用于含铅废水的吸附处理。(The invention discloses a preparation method and application of iron-doped hydroxyapatite/mulberry stem biochar. Grinding mulberry stems and carbonizing to obtain mulberry stem charcoal powder; adding a calcium nitrate solution and a ferrous chloride tetrahydrate solution into a beaker according to the molar ratio (Ca + Fe)/P being 1.67, adding the mulberry tree stalk biochar into the mixed solution, adding a diammonium hydrogen phosphate solution, and adding ammonia water under stirring; filtering, washing, drying and sieving to obtain the iron-doped hydroxyapatite/mulberry stem biochar. The invention is easy to operate and low in cost; the obtained material is applied to the adsorption treatment of lead-containing wastewater.)

1. A preparation method of iron-doped hydroxyapatite/mulberry stem biochar is characterized by comprising the following specific steps:

(1) peeling mulberry stems, crushing the mulberry stems into powder by using a universal crusher, sieving the powder by using a 20-mesh sieve, and drying the powder in an oven at the temperature of 60-80 ℃ for later use;

(2) placing the mulberry tree stems obtained in the step (1) into a crucible, placing the crucible containing the mulberry tree stems into a muffle furnace, heating to 600-800 ℃ at a heating rate of 10 min/DEG C, keeping for 2-6 hours to obtain mulberry tree stem biochar, grinding, sieving with a 100-mesh sieve, and sealing for storage;

(3) adding 500mL of calcium nitrate solution with the concentration of 0.1-0.5 mol/L and 50mL of ferrous chloride solution with the concentration of 0.1-0.5 mol/L into a 2000mL beaker according to the molar ratio (Ca + Fe)/P = 1.67;

(4) adding 50g of the mulberry tree stalk biochar obtained in the step (2) into the mixed solution obtained in the step (3), and then adding 300mL of diammonium hydrogen phosphate solution with the concentration of 0.1-0.5 mol/L;

(5) rapidly adding an ammonia water solution with the volume percentage concentration of 8-10% into the mixed suspension solution obtained in the step (4) under stirring, and adjusting the pH value of the solution to 8.0-10.0;

(6) after the pH value of the mixed suspension in the step (5) is kept stable and unchanged, stirring the mixed suspension in the step (5) for 30 minutes at room temperature by using a magnetic stirrer at the rotating speed of 200r/min, and then aging in a water bath for 4-6 hours at 70 ℃;

(7) after the mixed suspension in the step (5) is naturally cooled, measuring the pH value of the supernatant, centrifugally separating the mixed suspension at the rotating speed of 4000r/min for 5 minutes, after solid-liquid separation, washing the mixed suspension for many times by using ultrapure water until the pH value is about 7.0, and then washing the mixed suspension by using absolute ethyl alcohol;

(8) and (3) drying the product obtained in the step (7) at 80 ℃ for 24-30 hours, naturally cooling, grinding, and sieving with a 100-mesh sieve to obtain the iron-doped hydroxyapatite/mulberry stem biochar.

2. The application of the iron-doped hydroxyapatite/mulberry stem biochar prepared by the preparation method according to claim 1 is characterized in that the iron-doped hydroxyapatite/mulberry stem biochar is applied to the adsorption treatment of lead-containing wastewater.

Technical Field

The invention relates to a preparation method of iron-doped hydroxyapatite/mulberry stalk biomass charcoal, in particular to a method for preparing iron-doped hydroxyapatite/mulberry stalk biomass charcoal by taking waste mulberry stalks as main raw materials and application thereof.

Background

Nowadays, socio-economic development is rapid, and the environmental problems are more serious. China, as one of the largest lead producing countries and consuming countries in the world, discharges a large amount of lead-containing wastewater from industries such as mining, chemical engineering and the like every year. Lead can enter the environment through the combustion of fossil fuels, the smelting of sulfur-containing minerals, and the discharge of acidic mine wastewater, thus contaminating surface and groundwater.

Lead and its compounds are an accumulating poison, lead has a toxic effect on aquatic organisms at low concentrations and causes disorders of the nervous system and blood circulation in humans. Drinking water and farmland irrigation water with lead content exceeding the standard need to be effectively treated. The method for treating the lead-containing wastewater mainly comprises a chemical precipitation method, an adsorption method, an electrolysis method and the like, wherein the adsorption method is widely concerned and applied due to the advantages of simple operation, good effect, low cost and the like.

The biochar has inherent characteristics of porous structure, high specific surface area, large pore volume, acid and alkali corrosion resistance, rich functional groups and the like, and is widely researched and applied in the fields of pollutant treatment, water body purification and the like. However, due to the small diameter of the biochar particles, it is difficult to separate the biochar particles from the solution after the wastewater is treated. The inside of the biological carbon treatment device may contain a large amount of pollutants, which causes secondary pollution and is not beneficial to the regeneration and the reutilization of the biological carbon, so the practical application of the biological carbon in the wastewater treatment is limited. In order to obtain biochar with better adsorption performance, a large number of researchers prepare materials with new performance and new structures by combining biochar with other materials by physical and chemical methods, and the adsorption effect of the biochar is superior to that of original biochar.

In recent years, the composite materials for removing lead, which are commonly used at home and abroad, can be divided into the following types: biochar-magnetic composite materials, biochar-nano composite materials and biochar-inorganic composite materials. For example: studies by Zhang Like et al have demonstrated Hydroxyapatite (HAP) and gamma-Fe₂O₃The particles are all loaded on the biochar. Compared with original biochar, the HAP/gamma-Fe after compounding₂O₃BC to Pb²⁺Has obviously improved adsorption performance and good performanceMagnetic separation ability. When the temperature is 298.15K, the maximum adsorption capacity reaches 210.85 mg/g. The study of Zhou et al showed that the chitosan/charcoal has a Pb-free interaction with the enzyme²⁺The adsorption capacity of the carbon is improved by 150 percent compared with the original pure biochar, and the maximum adsorption quantity of the carbon to lead is 14.3 mg/g. The single charcoal has low adsorption capacity to lead, so researchers want to add other materials capable of interacting with pollutants into the charcoal material to prepare a composite material, thereby improving the lead adsorption effect of the charcoal.

Therefore, the waste mulberry stems are used as raw materials to prepare the biochar, and the ferrous chloride tetrahydrate, the calcium nitrate and the diammonium phosphate are used as auxiliary materials to prepare the iron-doped hydroxyapatite/mulberry stem biochar. The iron-doped hydroxyapatite/mulberry stem biochar combines the advantages of biochar, hydroxyapatite and ferric oxide, and can efficiently remove lead in lead-containing wastewater.

Disclosure of Invention

The invention aims to provide a method for preparing iron-doped hydroxyapatite/mulberry stalk biochar by using mulberry stalks as raw materials and ferrous chloride tetrahydrate, calcium nitrate and diammonium phosphate as auxiliary materials under normal pressure by adopting a sol-gel method and an application thereof.

The method comprises the following specific steps:

(1) the mulberry stems are peeled, crushed into powder by a universal crusher, sieved by a 20-mesh sieve, and placed in an oven to be dried at 60-80 ℃ for later use.

(2) Putting the mulberry tree stems obtained in the step (1) into a crucible, putting the crucible containing the mulberry tree stems into a muffle furnace, heating to 600-800 ℃ at a heating rate of 10 min/DEG C, keeping for 2-6 hours to obtain the mulberry tree stem biochar, grinding, sieving with a 100-mesh sieve, and sealing for storage.

(3) 500mL of a calcium nitrate solution having a concentration of 0.1 to 0.5mol/L and 50mL of a ferrous chloride solution having a concentration of 0.1 to 0.5mol/L were placed in a 2000mL beaker at a molar ratio (Ca + Fe)/P of 1.67.

(4) And (3) adding 50g of the mulberry stalk biochar obtained in the step (2) into the mixed solution obtained in the step (3), and then adding 300mL of diammonium hydrogen phosphate solution with the concentration of 0.1-0.5 mol/L.

(5) And (3) rapidly adding an ammonia water solution with the volume percentage concentration of 8-10% into the mixed suspension solution obtained in the step (4) under stirring, and adjusting the pH value of the solution to 8.0-10.0.

(6) And (3) after the pH value of the mixed suspension in the step (5) is kept stable and unchanged, stirring the mixed suspension in the step (5) for 30 minutes at room temperature by using a magnetic stirrer at the rotating speed of 200r/min, and then aging for 4-6 hours in a water bath at 70 ℃.

(7) And (5) after the mixed suspension is naturally cooled, measuring the pH value of the supernatant, centrifugally separating the mixed suspension for 5 minutes at the rotating speed of 4000r/min, washing the mixed suspension for many times by using ultrapure water after solid-liquid separation until the pH value is about 7.0, and then washing the mixed suspension by using absolute ethyl alcohol.

(8) And (3) drying the product obtained in the step (7) at 80 ℃ for 24-30 hours, naturally cooling, grinding, and sieving with a 100-mesh sieve to obtain the iron-doped hydroxyapatite/mulberry stem biochar (Fe-HMp).

The invention provides a composite material for effectively adsorbing lead, namely iron-doped hydroxyapatite/mulberry stem biochar. When the initial lead concentration in the solution is 400mg/L, the removal rate of lead is more than 99%, the lead concentration in the adsorption equilibrium solution is lower than 1.0mg/L, and the lead content in the adsorption equilibrium solution reaches the national comprehensive sewage discharge standard (GB 8978-2002); when the initial lead concentration in the solution is 100mg/L, the lead concentration in the adsorption equilibrium solution is lower than the limit value of 0.01mg/L of lead in the Water quality Standard of the world health organization.

The invention has simple process equipment and easy operation. Mainly takes waste mulberry stems as raw materials, and reduces the cost. The prepared composite material has good adsorption effect on lead in the aqueous solution, the maximum adsorption capacity reaches 303.03mg/g, and the composite material is applied to adsorption treatment of lead-containing wastewater.

Drawings

Fig. 1 is a graph showing the influence of iron-doped hydroxyapatite/biochar prepared according to an embodiment of the present invention on adsorption effects of different initial lead concentrations.

FIG. 2 is an infrared spectrum of mulberry stem biochar and iron-doped hydroxyapatite/mulberry stem biochar prepared according to the embodiment of the invention.

Fig. 3 is an XRD chart of the mulberry stalk biochar and iron-doped hydroxyapatite/mulberry stalk biochar prepared according to the embodiment of the present invention.

Fig. 4 is SEM images of the mulberry stem biochar and the iron-doped hydroxyapatite/mulberry stem biochar prepared according to the embodiment of the present invention.

Detailed Description

Example (b):

(1) peeling mulberry stems, crushing into powder by a universal crusher, sieving by a 20-mesh sieve, and drying in an oven at 80 ℃ for later use.

(2) Putting the mulberry tree stems obtained in the step (1) into a crucible, putting the crucible containing the mulberry tree stems into a muffle furnace, heating to 700 ℃ at a heating rate of 10 min/DEG C, keeping for 2 hours to obtain the mulberry tree stem biochar, grinding, sieving with a 100-mesh sieve, and sealing for storage.

(3) 500mL of a 0.2mol/L calcium nitrate solution and 50mL of 0.2mol/L ferrous chloride were added to a 2000mL beaker at a molar ratio (Ca + Fe)/P of 1.67.

(4) And (3) adding 50g of the mulberry stem biochar obtained in the step (2) into the beaker mixed solution in the step (3), and then adding 300mL of diammonium hydrogen phosphate solution with the concentration of 0.2mol/L into the beaker.

(5) And (4) rapidly adding an aqueous ammonia solution with the volume percentage concentration of 8% into the mixed suspension obtained in the step (4) under stirring, and adjusting the pH value of the solution to 10.0.

(6) And (3) after the pH value of the mixed suspension obtained in the step (5) is kept stable, stirring the mixed suspension obtained in the step (5) for 30 minutes at room temperature by using a magnetic stirrer at the rotating speed of 200r/min, and then aging the mixed suspension for 4 hours in a water bath at 70 ℃.

(7) And (4) after the mixed suspension in the step (6) is naturally cooled, measuring the pH value of the supernatant, centrifugally separating the mixed suspension at the rotating speed of 4000r/min for 5 minutes, washing the mixed suspension for many times by using ultrapure water until the pH value is about 7.0, and then washing the mixed suspension by using absolute ethyl alcohol.

(8) And (3) drying the product obtained in the step (7) at the temperature of 80 ℃ for 24 hours, naturally cooling, grinding, and sieving by a 100-mesh sieve to obtain the iron-doped hydroxyapatite/mulberry stem biochar (Fe-HMp).

The iron-doped hydroxyapatite/mulberry stem biomass charcoal prepared in the embodiment is applied to the adsorption treatment of the lead-containing wastewater.

0.1g of the iron-doped hydroxyapatite/mulberry stem biochar prepared in the example was weighed into a series of 100mL polyethylene centrifuge tubes, and the pH value was adjusted to 5.0 with 0.1mol/L sodium hydroxide solution or hydrochloric acid solution, the volume was 50mL, Pb²⁺Pb-containing solution with concentrations of 10, 50, 100, 300, 400, 500, and 600mg/L, respectively²⁺The solution was added to the plastic centrifuge tube described above. Oscillating and adsorbing for 24h at the temperature of 25 ℃ and the oscillating rotation speed of 200 r/min. The plastic centrifuge tube was then placed in a centrifuge, centrifuged at 4000r/min for 5 minutes, the supernatant was filtered using a syringe filter (0.22 μm filter), and the remaining Pb concentration in the filtrate was measured using an inductively coupled plasma emission spectrometer (ICP-OES), the experimental results being shown in fig. 1.

The phase structure and the composition were measured by a fourier spectrometer and an X-ray diffractometer, and the results are shown in fig. 2 and 3. The morphology of the iron-doped hydroxyapatite/mulberry stem biochar is analyzed by a field emission scanning electron microscope, and the result is shown in figure 4.