CN112023876A - Preparation of magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material and application of phosphorus removal in wastewater - Google Patents

Abstract

The invention belongs to the technical field of composite materials, and relates to a method for preparing modified biomass carbon materials, in particular to a method for preparing a magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material, comprising: soaking crushed coconut shells in lye Remove impurities, wash, add chlorous acid acidified with acetic acid to decolorize, clean and dry to obtain coconut husk fibers; continue to soak in aluminum nitrate solution, filter, dry, and calcinate at 200-800°C in nitrogen atmosphere to obtain Al ₂ O ₃ /CSF; according to the solid-liquid ratio of 0.3-1.8 g: 0.1-0.9 g: 0.05-1.0 g: 50-200 mL, combine magnesium nitrate hexahydrate, Al ₂ O ₃ /CSF, hexamethylenetetramine Dissolved in deionized water, reacted at 60-180 °C for 6-48 h, filtered, washed, and calcined at high temperature to obtain Mg-Al/CSF. The method utilizes common waste coconut shells as biomass resources, and is prepared by hydrothermal and calcining methods, which can realize the efficient removal of phosphorus in wastewater, the materials can be recycled, the preparation cost can be reduced to the greatest extent, and the adsorption performance can be improved.

Description

Preparation of magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material and application of phosphorus removal in wastewater

technical field

The invention belongs to the technical field of composite materials, and relates to a preparation method of modified biomass carbon materials, in particular to the preparation of magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption materials and the application of removing phosphorus in wastewater.

Background technique

In recent years, with the economic development and social and industrial modernization, the discharge of various environmental pollutants is increasing, especially the sharp increase in phosphorus discharge, which has caused serious damage to the natural water environment. At present, the commonly used wastewater phosphorus removal technologies include chemical precipitation, adsorption, ion exchange and biological methods. Simple precipitation method is difficult to remove a large number of phosphorus compounds in sewage; biological phosphorus removal treatment has limited effect; ion exchange method has a series of disadvantages such as expensive resin preparation, low exchange capacity and poor selectivity. The adsorption method has the advantages of high efficiency, low cost, simple operation, regeneration, and sustainability. The key to phosphorus removal by adsorption is the selection of adsorbents. At present, the commonly used adsorbents include activated carbon, zeolite, etc., which often produce a large amount of sludge during the use process, and the application effect is poor. Therefore, it is urgent to find environmentally friendly adsorbents that can efficiently remove phosphorus from wastewater. At the same time, the use of biomass materials to prepare composite materials that can be used as adsorbents has received extensive attention in environmental governance.

Biomass-based carbon materials can usually be obtained from discarded agricultural and forestry crops, and have attracted extensive attention due to their easy availability and good adsorption properties. However, the preparation of biomass materials for phosphorus adsorption in water using agricultural and forestry wastes as precursors Report less. Using agricultural and forestry wastes as precursors of biomass composite materials can not only make full use of agricultural and forestry wastes, but also treat wastes with waste, so as to achieve the purpose of protecting the environment. Biochar material has adsorption capacity and is an effective method for phosphorus removal. Doping metal or metal oxides in the biomass carbon material can improve the adsorption capacity of the adsorbent, and the composite material has catalytic properties, which can remove pollutants through multiple channels.

In the invention, waste coconut shells are used as biomass carbon precursors, magnesium-aluminum bimetallic composite oxides are selected, and magnesium-aluminum bimetallic composite oxides/biomass carbon composite materials with hierarchical structure are prepared by an in-situ growth method, and the composite materials are Applied to the removal of phosphorus in wastewater. In addition, using agricultural and forestry wastes as the precursors of adsorbents not only makes full use of abandoned agricultural and forestry crops generated in the natural environment, but also provides a good adsorbent for removing phosphorus from water.

SUMMARY OF THE INVENTION

In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to disclose a preparation method of a magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material.

Technical solutions

A preparation method of magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material, comprising the following steps:

a) Soak the crushed coconut shell in sodium hydroxide solution, stir at 60～150℃ for 1～8h, preferably 1M, stir at 80℃ for 3h, after removing impurities, wash with deionized water, add acetic acid acidified Decolorization is carried out in the sodium chlorate solution, then the decolorized biomass is washed with deionized water, and dried to obtain coconut husk fibers;

b) Dissolving 1-20 g of aluminum nitrate nonahydrate per 100 mL of deionized water, soak the obtained coconut husk fibers for 5-20 h and filter, preferably soak 5 g for 10 h, and calcine the obtained sample in a nitrogen atmosphere at 200-800 °C 2～8h, preferably calcining at 400℃ for 4h, to obtain alumina-coated coconut husk fibers (Al ₂ O ₃ /CSF);

c) According to the solid-liquid ratio of 0.3～1.8g:0.1～0.9g:0.05～1.0g:50～200mL, preferably 0.9g:0.3g:0.5g:75mL, mix magnesium nitrate hexahydrate, Al ₂ O ₃ /CSF, Hexamethylenetetramine is dissolved in deionized water, and after fully stirring, the mixture is transferred to a stainless steel reaction kettle, reacted at 60-180°C for 6-48 hours, preferably at 120°C for 12 hours, filtered, washed, and the product after drying calcined at 200-800 °C for 2-8 h in nitrogen atmosphere, preferably 500 °C for 4 h, to obtain magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material (Mg-Al/CSF).

In the preferred disclosure example of the present invention, the concentration of the sodium hydroxide solution is 0.2-1.5M, and the sodium chlorite solution acidified with acetic acid is made by dissolving sodium chlorite in water according to 5% mass fraction and adjusting it with acetic acid pH is 4.

The magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material (Mg-Al/CSF) prepared according to the method of the present invention still retains the original coconut shell fiber structure in its morphology, and has a hierarchical structure nanometer grown on the surface. The flakes effectively increase the specific surface area of the Mg-Al/CSF material, thereby exposing more adsorption sites, which can be used to remove phosphorus elements in wastewater.

Another object of the present invention is to apply the prepared magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material (Mg-Al/CSF) to phosphorus removal in wastewater.

The method disclosed in the present invention is used to remove the phosphorus element in waste water, and the steps are as follows:

Add 10-40 mg of Mg-Al/CSF per 10 mL of 100 mg/L potassium dihydrogen phosphate solution, adjust the pH of the solution to 3-10, temperature 25-45 °C, and after adsorption for 2 hours, use a visible spectrophotometer to measure the phosphorus concentration at the wavelength of Detected at λ=700nm, and calculated the concentration of phosphorus.

Phosphorus removal rate is calculated by formula (1):

In the formula, R is the removal rate (%), C ₀ (mg/L) is the initial concentration of ions before adsorption, and C _e is the concentration of ions in the solution when the adsorption equilibrium time is t.

The characteristics of the present invention are:

(1) The prepared magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material (Mg-Al/CSF) has good biocompatibility, and the raw materials are easily obtained, the preparation process is simple, and the cost is low;

(2) The prepared magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material (Mg-Al/CSF) has an obvious hierarchical structure and more adsorption sites on the surface, and has a higher phosphorus content in wastewater. The adsorption capacity is moderate; the adsorption conditions are mild, a small amount of adsorbent can achieve a high removal rate, and the material can be recycled and reused.

The sodium hydroxide, acetic acid, hydrochloric acid, sodium chlorite, magnesium nitrate hexahydrate, hexamethylenetetramine, potassium dihydrogen phosphate and aluminum nitrate nonahydrate used in the present invention all come from Sinopharm Chemical Reagent Co., Ltd.

beneficial effect

The invention discloses a preparation method of a magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material (Mg-Al/CSF) for removing phosphorus elements in environmental wastewater, and uses common waste coconut shells as biomass resources , The composite material prepared by a simple hydrothermal and calcination method can achieve efficient removal of phosphorus in wastewater under the condition of a small amount of consumption, and the material can be recycled to minimize the preparation cost and improve the adsorption performance. The invention has good application prospects in the field of high-efficiency wastewater phosphorus removal, and has the advantages of energy saving, environmental protection, convenient recovery and the like.

Description of drawings

Fig. 1. SEM of coconut husk fibers (A, B), Al ₂ O ₃ /coconut husk fibers (C, D) and magnesium-aluminum bimetallic oxide/coconut husk carbon fibers (E, F) prepared in Example 3 ;

Figure 2. XRD of CSF, Al ₂ O ₃ /CSF and Mg-Al/CSF prepared in Example 3.

Detailed ways

The present invention will be described in detail below in conjunction with the examples, so that those skilled in the art can better understand the present invention, but the present invention is not limited to the following examples.

Unless otherwise defined, terms (including technical and scientific terms) used herein should be construed to have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will also be understood that terms used herein should be construed to have meanings consistent with their meanings in the context of this specification and related art and should not be interpreted in an idealized or excessive form unless expressly defined as such herein .

Example 1

A preparation method of magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material, comprising the following steps:

a) Soak the crushed coconut shells in 0.2M sodium hydroxide solution, stir at 60°C for 1 hour, remove impurities, wash with deionized water, and add to acetic acid acidified sodium chlorite solution (mass fraction 5%) Carry out decolorization treatment, then the decolorized biomass is washed with deionized water, and the coconut husk fiber is obtained after drying;

b) Dissolving 1 g of aluminum nitrate nonahydrate per 100 mL of deionized water, soak the obtained coconut husk fibers for 5 hours and then filter them. The samples obtained by drying are calcined at 200° C. for 2 hours under nitrogen conditions to obtain alumina-coated coconut husk fibers. (Al ₂ O ₃ /CSF);

c) According to the solid-liquid ratio of 0.3g:0.1g:0.05g:50mL, dissolve magnesium nitrate hexahydrate, Al ₂ O ₃ /CSF and hexamethylenetetramine in deionized water, and after thorough stirring, transfer the mixture to a In a stainless steel reactor, after reacting at 60 °C for 6 h, filtered, washed, and the dried product was calcined at 200 °C for 2 h in a nitrogen atmosphere to obtain magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material (Mg-Al/CSF ).

Phosphorus removal from wastewater:

Add 10 mg Mg-Al/CSF meter per 10 mL of 100 mg/L potassium dihydrogen phosphate solution, adjust the pH of the solution to 3, and after adsorption for 2 h at a temperature of 25 °C, the phosphorus concentration is detected with a visible spectrophotometer at a wavelength of λ=700 nm , and calculate the phosphorus concentration.

The phosphorus removal rate of the prepared adsorbent reached 58%.

Example 2

A preparation method of magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material, comprising the following steps:

a) Soak the crushed coconut shells in 0.5M sodium hydroxide solution, stir at 90°C for 4 hours, remove impurities, wash with deionized water, add acetic acid acidified sodium chlorite solution (mass fraction 5%) Carry out decolorization treatment, then the decolorized biomass is washed with deionized water, and the coconut husk fiber is obtained after drying;

b) Dissolving 10 g of aluminum nitrate nonahydrate per 100 mL of deionized water, soak the obtained coconut husk fibers for 8 hours and then filter them. The samples obtained by drying are calcined at 450° C. for 6 hours under nitrogen conditions to obtain alumina-coated coconut husk fibers. (Al ₂ O ₃ /CSF);

c) According to the solid-liquid ratio of 0.6g:0.25g:0.2g:90mL, dissolve magnesium nitrate hexahydrate, Al ₂ O ₃ /CSF and hexamethylenetetramine in deionized water, and after thorough stirring, transfer the mixture to a In a stainless steel reactor, after reacting at 90°C for 18h, filtered, washed, and the dried product was calcined at 500°C for 6h under nitrogen atmosphere to obtain magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material (Mg-Al/CSF ).

Phosphorus removal from wastewater:

Add 15mg Mg-Al/CSF meter per 10mL of 100mg/L potassium dihydrogen phosphate solution, adjust the pH of the solution to 7, and after adsorption for 2h at a temperature of 30°C, the phosphorus concentration is detected with a visible spectrophotometer at a wavelength of λ=700nm , and calculate the phosphorus concentration.

The phosphorus removal rate of the prepared adsorbent reached 66%.

Example 3

A preparation method of magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material, comprising the following steps:

a) Soak the crushed coconut shells in 1M sodium hydroxide solution, stir at 80°C for 3 hours, remove impurities, wash with deionized water, add acetic acid acidified sodium chlorite solution (mass fraction 5%) to carry out Decolorization treatment, then the decolorized biomass is washed with deionized water, and the coconut husk fiber is obtained after drying;

b) Dissolving 5 g of aluminum nitrate nonahydrate per 100 mL of deionized water, soak the obtained coconut husk fibers for 10 hours, filter them, and calcine the samples obtained by drying at 400° C. for 4 hours under nitrogen conditions to obtain alumina-coated coconut husk fibers. (Al ₂ O ₃ /CSF);

c) According to the solid-liquid ratio of 0.9g:0.3g:0.5g:75mL, dissolve magnesium nitrate hexahydrate, Al ₂ O ₃ /CSF, and hexamethylenetetramine in deionized water, and after thorough stirring, transfer the mixture to a In a stainless steel reactor, after reacting at 120 °C for 12 h, filtered, washed, and the dried product was calcined at 500 °C for 4 h under nitrogen atmosphere to obtain magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material (Mg-Al/CSF ).

Phosphorus removal from wastewater:

Add 25mg Mg-Al/CSF meter per 10mL of 100mg/L potassium dihydrogen phosphate solution, adjust the pH of the solution to 6, after adsorption for 2h at a temperature of 45°C, the phosphorus concentration is detected with a visible spectrophotometer at wavelength λ=700nm , and calculate the phosphorus concentration.

The phosphorus removal rate of the prepared adsorbent reached 94.5%.

Example 4

A preparation method of magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material, comprising the following steps:

a) Soak the crushed coconut shells in 1.2M sodium hydroxide solution, stir at 150°C for 4 hours, remove impurities, wash with deionized water, and add to acetic acid acidified sodium chlorite solution (mass fraction 5%) Carry out decolorization treatment, then the decolorized biomass is washed with deionized water, and the coconut husk fiber is obtained after drying;

b) Dissolving 15g of aluminum nitrate nonahydrate per 100mL of deionized water, soak the obtained coconut husk fibers for 16 hours, filter them, and calcine the obtained samples under nitrogen conditions at 350° C. for 8 hours to obtain alumina-coated coconut husk fibers (Al ₂ O ₃ /CSF);

c) According to the solid-liquid ratio of 1.2g:0.6g:0.8g:100mL, dissolve magnesium nitrate hexahydrate, Al ₂ O ₃ /CSF and hexamethylenetetramine in deionized water, and after thorough stirring, transfer the mixture to a In a stainless steel reactor, after reacting at 120°C for 24h, filtered, washed, and the dried product was calcined at 600°C for 6h under nitrogen atmosphere to obtain magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material (Mg-Al/CSF ).

Phosphorus removal from wastewater:

Add 30 mg of Mg-Al/CSF meter per 10 mL of 100 mg/L potassium dihydrogen phosphate solution, adjust the pH of the solution to 8, and after adsorption for 2 h at a temperature of 40 °C, the phosphorus concentration is detected with a visible spectrophotometer at wavelength λ=700 nm , and calculate the phosphorus concentration.

The phosphorus removal rate of the prepared adsorbent reached 78.5%.

Example 5

A preparation method of magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material, comprising the following steps:

a) Soak the crushed coconut shells in 1.5M sodium hydroxide solution, stir at 150°C for 8 hours, remove impurities, wash with deionized water, and add to acetic acid acidified sodium chlorite solution (mass fraction 5%) Carry out decolorization treatment, then the decolorized biomass is washed with deionized water, and the coconut husk fiber is obtained after drying;

b) Dissolving 20 g of aluminum nitrate nonahydrate per 100 mL of deionized water, soak the obtained coconut husk fibers for 20 hours, filter them, and calcine the obtained samples at 800°C for 8 hours under nitrogen conditions to obtain alumina-coated coconut husk fibers (Al ₂ O ₃ /CSF);

c) According to the solid-to-liquid ratio of 1.8g:0.9g:1.0g:200mL, dissolve magnesium nitrate hexahydrate, Al ₂ O ₃ /CSF, and hexamethylenetetramine in deionized water, and after thorough stirring, transfer the mixture to a In a stainless steel reactor, after reacting at 180 °C for 48 h, filtered, washed, and the dried product was calcined at 800 °C for 8 h under nitrogen atmosphere to obtain magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material (Mg-Al/CSF ).

Phosphorus removal from wastewater:

Add 40 mg of Mg-Al/CSF meter per 10 mL of 100 mg/L potassium dihydrogen phosphate solution, adjust the pH of the solution to 10, and after adsorption for 2 h at a temperature of 45 °C, the phosphorus concentration is detected with a visible spectrophotometer at a wavelength of λ=700 nm , and calculate the phosphorus concentration.

The phosphorus removal rate of the prepared adsorbent reached 83%.

The above descriptions are only the embodiments of the present invention, and are not intended to limit the scope of the patent of the present invention. Any equivalent structure or equivalent process transformation made by the description of the present invention, or directly or indirectly applied in other related technical fields, are the same as The principles are included in the scope of patent protection of the present invention.

Claims (10)

1. a preparation method of magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material, is characterized in that, comprises the steps: a) Soak the crushed coconut shells in sodium hydroxide solution, stir at 60～150℃ for 1～8 h, remove impurities, wash with deionized water, add acetic acid acidified sodium chlorite solution to decolorize Treatment, then the decolorized biomass is washed with deionized water, and the coconut husk fiber is obtained after drying; b) Calculated by dissolving 1-20 g aluminum nitrate nonahydrate per 100 mL of deionized water, soak the obtained coconut husk fiber for 5-20 h, filter it, and calcine the obtained sample at 200-800 ℃ for 2-20 hours in a nitrogen atmosphere. 8 h to obtain alumina-coated coconut husk fiber Al ₂ O ₃ /CSF; c) According to the solid-liquid ratio of 0.3～1.8 g : 0.1～0.9 g : 0.05～1.0 g : 50～200 mL, dissolve magnesium nitrate hexahydrate, Al ₂ O ₃ /CSF and hexamethylenetetramine in deionized water , after fully stirring, the mixture was transferred to a stainless steel reactor, reacted at 60-180 °C for 6-48 h, filtered, washed, and the dried product was calcined at 200-800 °C for 2-8 h in a nitrogen atmosphere to obtain . 2. The preparation method of the magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material according to claim 1, wherein the concentration of the sodium hydroxide solution in step a) is 0.2-1.5 M, and the acetic acid The acidified sodium chlorite solution is made by dissolving sodium chlorite in water according to 5% mass fraction and adjusting the pH to 4 with acetic acid. 3. The preparation method of magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material according to claim 1, characterized in that: described in step a), the pulverized coconut shell is soaked in 1 M sodium hydroxide solution , and stirred at 80°C for 3h. 4. the preparation method of magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material according to claim 1, is characterized in that: according to every 100 mL of deionized water in step b), dissolve 5 g of aluminum nitrate nonahydrate according to The obtained coconut husk fibers were soaked for 10 h and filtered. 5. The preparation method of the magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material according to claim 1, wherein the sample obtained by drying in step b) is calcined at 400°C for 4 h in a nitrogen atmosphere . 6. the preparation method of magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material according to claim 1, is characterized in that: described in step c) according to solid-liquid ratio 0.9 g: 0.3 g: 0.5 g: 75 mL, magnesium nitrate hexahydrate, Al ₂ O ₃ /CSF, hexamethylenetetramine were dissolved in deionized water. 7. The preparation method of magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material according to claim 1, wherein the mixture is transferred to a stainless steel reactor as described in step c), and the reaction is carried out at 120°C for 12 h . 8. The preparation method of magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material according to claim 1, characterized in that: the product after drying described in step c) is calcined at 500 ° C for 4 h in a nitrogen atmosphere . 9. The magnesium-aluminum composite oxide modified coconut shell biomass charcoal adsorption material prepared according to any one of claims 1-8. 10. An application of the magnesium-aluminum composite oxide modified coconut shell biomass carbon adsorption material as claimed in claim 9, characterized in that: it is applied to the phosphorus removal of waste water.

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