CN103861567A - Preparation method of hydroxyapatite/bagasse active carbon - Google Patents

Abstract

The invention discloses a preparation method of hydroxyapatite/bagasse activated carbon. Add 250ml of 4.4mol/L ammonium acetate buffer solution to 250ml of 0.05mol/L~0.5mol/L calcium acetate solution, mix well, then add 10~60g of bagasse, after electric stirring, use ultrasonic vibration for 30~60 minutes , let it stand for 24~48 hours; add 500ml0.015mol/L~0.15mol/L ammonium dihydrogen phosphate solution to the mixture of calcium acetate, ammonium acetate and bagasse under rapid stirring, adjust the pH value to 7.5~8.0, at room temperature Stir for 10 minutes; heat in a water bath to 100°C and react for 48-60 hours to obtain a mixed suspension solution of hydroxyapatite/bagasse; naturally cool, filter, wash, and dry at 70°C for 16 hours to obtain a mixed suspension of hydroxyapatite/bagasse Mixture; carbonized at 450°C~650°C, then ground and passed through a 100-mesh sieve. The process of the invention is simple and the cost is low; the prepared product can be widely used in the process of advanced treatment of cadmium- and lead-containing wastewater in industrial and mining enterprises.

Description

Preparation method of hydroxyapatite/bagasse activated carbon

technical field

The invention relates to a preparation method of hydroxyapatite/bagasse activated carbon.

Background technique

With the rapid development of modern industry, the discharge of heavy metal wastewater containing cadmium and lead is increasing, and the pollution of heavy metals has become one of the most serious environmental problems. Therefore, the treatment of heavy metal wastewater containing cadmium and lead is urgent. Among the many heavy metals, cadmium ions are one of the most toxic and most harmful to human health. When cadmium ions accumulate in the human body to a certain dose, it is easy to cause lesions in the kidneys, intestines, and bones of the human body. The harm of lead ions to the human body is quite extensive. If the human body takes too much lead, it will cause lead anemia and serious damage to the nervous system, bone hematopoietic system, digestive system, kidney and reproductive system. The current methods for treating heavy metal wastewater containing cadmium and lead mainly include co-precipitation, flocculation, redox, photocatalytic degradation, ion exchange, solvent extraction, adsorption, membrane separation, etc. The chemical precipitation method will produce a large amount of excess sludge containing heavy metals, which increases the treatment cost. There are also certain difficulties in the recovery of cadmium and lead, and the treatment cost of the ion exchange method is also relatively high. In recent years, many researchers have taken the removal of cadmium and lead by adsorption as a research direction. Commonly used adsorbents are: activated carbon, iron oxyhydroxide, goethite, titanium dioxide, and activated alumina, etc., but most of these adsorbents are in the form of powders. Although the specific surface area is large, the adsorption capacity is still relatively low.

Apatite is a calcium phosphate mineral that exists widely in nature. According to the types of anions in it, it can be divided into different subspecies of minerals such as fluorine, chlorine, and hydroxyapatite. Among them, the research and application of hydroxyapatite are the most extensive. The molecular formula of hydroxyapatite is Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ , which is a hexagonal crystal system. This crystal chemical feature enables different types of heavy metals to replace the calcium in hydroxyapatite, and has a good ion Adsorption and exchange characteristics, can absorb and recover fluoride ions in groundwater, heavy metals in industrial wastewater and organic polymers, and hydroxyapatite has good coordination with the environment, and is not easy to cause secondary pollution, so it has become a concern New environmental adsorption material. A large amount of literature shows that hydroxyapatite has a significant effect on the removal of cadmium and lead. Activated carbon is an excellent adsorbent, but its adsorption effect on cadmium and lead is limited. Therefore, how to organically combine two kinds of adsorbents with excellent adsorption properties so that the adsorption properties can achieve the effect of complementing each other is a hot issue in current research. Therefore, the preparation of hydroxyapatite/bagasse activated carbon composite adsorbent with bagasse as the main raw material has favorable development prospects and practical significance.

Contents of the invention

The purpose of the present invention is to provide a method of hydrothermal synthesis and calcination under normal pressure, using bagasse as the main raw material, and calcium acetate, ammonium acetate and ammonium dihydrogen phosphate as auxiliary materials to prepare hydroxyapatite/bagasse Activated carbon composite adsorbent.

At present, among the adsorption materials that have been studied more for the adsorption and removal of cadmium and lead, the single substances include hydrated manganese dioxide, goethite, activated carbon fiber, titanium dioxide and nano-metal aluminum powder, etc.; the composite substances include modified bentonite, modified Zeolite, illite, modified peanut shells, plant ash, weathered coal, etc. The main components of some of these adsorption materials are iron-aluminum oxides, which are also the main substances for adsorbing cadmium and lead, while the main components of some adsorption materials are some organic substances such as activated carbon. In order to overcome the low adsorption capacity and limited adsorption capacity of the existing cadmium and lead adsorbents, and make full use of the abundant bagasse resources in Guangxi. The invention provides a preparation method of cadmium and lead adsorption material-hydroxyapatite/bagasse activated carbon. Hydroxyapatite/bagasse activated carbon can not only reduce the concentration of cadmium and lead in water samples containing cadmium and lead after treatment to less than 0.050 mg·L ^-1 , but also has a large adsorption capacity. at 5.0 mg·L ^-1 . The concentrations of cadmium and lead in water samples after adsorption equilibrium were lower than 0.01 mg·L ^-1 .

The specific steps are:

(1) Dry the bagasse in an oven at 80°C, crush it and pass it through a 20-mesh sieve for later use.

(2) Add 250 ml of calcium acetate solution with a concentration of 0.05 mol/L to 0.5 mol/L in a 2L beaker, then add 250 ml of ammonium acetate buffer solution with a concentration of 4.4 mol/L, mix well, and add 10 to 60 grams of The bagasse obtained in step (1) is electrically stirred, then ultrasonically oscillated for 30-60 minutes, and left to stand for 24-48 hours.

(3) Add 500ml of ammonium dihydrogen phosphate solution with a concentration of 0.015mol/L~0.15mol/L to the product of step (2) under rapid stirring, and slowly add it with a concentration of 10% by mass under stirring with an automatic titrator. % ammonia water to carefully adjust the pH value of the reaction to 7.5-8.0, and stir at room temperature for 10 minutes.

(4) Place the product obtained in step (3) in a constant temperature water bath, cover the glass watch glass, heat the water bath to 100°C, and react for 48-60 hours.

(5) Cool the product obtained in step (4) naturally, filter, measure and record the final pH value of the filtrate. The solid-phase precipitate was repeatedly washed twice with ultrapure water, and then washed once with absolute ethanol, and the filter cake was placed in a porcelain plate and dried at 70°C for 16 hours to obtain a hydroxyapatite/bagasse mixture.

(6) Carbonize the hydroxyapatite/bagasse mixture obtained in step (5) at 450°C to 650°C to obtain a hydroxyapatite/bagasse activated carbon composite; then grind and pass through a 100-mesh sieve to obtain hydroxyapatite / Bagasse Activated Carbon.

The process of the invention is simple and easy, and since the bagasse is used as the main raw material, the production cost is greatly reduced, and various performance indexes of the product are improved; the prepared product can be widely used in industrial and mining enterprises for advanced treatment of waste water containing cadmium and lead.

Description of drawings

   Fig. 1, Fig. 2, Fig. 3 are the scanning electron micrographs of the hydroxyapatite/bagasse activated carbon prepared in the embodiment of the present invention.

Detailed ways

Example:

(1) Dry the bagasse in an oven at 80°C, crush it with a universal crusher and pass it through a 20-mesh sieve for later use.

(2) Add 250 ml of calcium acetate solution with a concentration of 0.2 mol/L to a 2L beaker, then add 250 ml of ammonium acetate buffer solution with a concentration of 4.4 mol/L, mix well, and add 50 grams of bagasse obtained in step (1) , after electric stirring, oscillate ultrasonically for 30 minutes, and let stand for 24 hours.

(3) Add 500ml ammonium dihydrogen phosphate solution with a concentration of 0.06mol/L to the product obtained in step (2) under rapid stirring, and use an automatic titrator to slowly add ammonia water with a mass percentage concentration of 10% under stirring. The pH of the reaction was adjusted to 7.5 and stirred at room temperature for 10 minutes.

(4) Place the product obtained in step (3) in a constant temperature water bath, cover the glass watch glass, heat the water bath to 100°C, and react for 48 hours.

(5) Cool the product obtained in step (4) naturally, filter, measure and record the final pH value of the filtrate. The solid-phase precipitate was repeatedly washed twice with ultrapure water, and then washed once with absolute ethanol. The filter cake was placed in a porcelain plate and dried at 70° C. for 16 hours to obtain a hydroxyapatite/bagasse mixture.

(6) Carbonize the hydroxyapatite/bagasse mixture obtained in step (5) at 600°C to obtain a hydroxyapatite/bagasse activated carbon composite; then grind and pass through a 100-mesh sieve to obtain hydroxyapatite/bagasse activated carbon.

The phase, structure and composition of the prepared hydroxyapatite/bagasse activated carbon were tested by a German Bruker-axs D8ADVANCE X-ray diffractometer, with a diffraction angle range of 2θ=10-90° and a diffraction rate of 4°/min . The morphology and particle size of the samples were observed by scanning electron microscopy. The electron microscope test adopts the JSM-5610LV scanning electron microscope of Japan Electronics, and the morphology is observed at a magnification of 5000-20000 times.

Claims (1)

1. a preparation method of hydroxyapatite/bagasse activated carbon, is characterized in that concrete steps are: (1) Dry the bagasse in an oven at 80°C, crush it and pass it through a 20-mesh sieve for later use; (2) Add 250 ml of calcium acetate solution with a concentration of 0.05 mol/L to 0.5 mol/L in a 2L beaker, then add 250 ml of ammonium acetate buffer solution with a concentration of 4.4 mol/L, mix well, and add 10 to 60 grams of The bagasse obtained in step (1) is electrically stirred, then ultrasonically oscillated for 30-60 minutes, and left to stand for 24-48 hours; (3) Add 500ml of ammonium dihydrogen phosphate solution with a concentration of 0.015mol/L~0.15mol/L to the product of step (2) under rapid stirring, and use an automatic titrator to slowly add the solution with a concentration of 10% by mass under stirring. % ammonia water to adjust the pH value of the reaction to 7.5~8.0, and stir at room temperature for 10 minutes; (4) Place the product obtained in step (3) in a constant temperature water bath, cover the glass watch glass, heat the water bath to 100°C, and react for 48 to 60 hours; (5) Cool the product obtained in step (4) naturally, filter, measure and record the final pH value of the filtrate; wash the solid phase precipitate twice with ultrapure water, and then wash it once with absolute ethanol, and place the filter cake on a porcelain plate Dry at 70°C for 16 hours to obtain a hydroxyapatite/bagasse mixture; (6) Carbonize the hydroxyapatite/bagasse mixture obtained in step (5) at 450°C to 650°C to obtain a hydroxyapatite/bagasse activated carbon composite; then grind and pass through a 100-mesh sieve to obtain hydroxyapatite / Bagasse Activated Carbon.

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