CN106390927B - Preparation method of biological carbon composite adsorption material for removing phosphate from surface water - Google Patents

Abstract

The invention discloses a preparation method of a biological carbonaceous composite adsorption material for removing phosphate in surface water, and belongs to the field of biological carbonaceous adsorption materials. The preparation method specifically includes the following steps: (1) washing, air-drying, and cutting the pomelo peel and orange peel; (2) heating and pyrolyzing the above-mentioned granular solids, cooling and crushing to prepare carbonized pomelo peel and carbonized orange peel; (3) The pyrolyzed material is modified, and ferrous sulfate, sodium thiosulfate, and cetyltrimethylammonium bromide are respectively modified; (4) washed with deionized water and dried to obtain the modified product. Biological carbonaceous adsorbents. After the surface sewage with a phosphate concentration of 10mg/L is treated by the adsorption material of the present invention, the phosphate content of the water body reaches the surface water environmental quality standard (GB 3838-2002) Class V (≤0.4mg/L). The invention has the characteristics of low cost, high adsorption efficiency, wide application and the like, not only realizes the resource utilization of waste, but also brings good social and economic benefits.

Description

Preparation of a biological carbonaceous composite adsorption material for removing phosphate from surface water method

technical field

The invention belongs to the field of biological carbonaceous adsorption materials, in particular to the preparation of adsorption materials for phosphate sewage treatment, and in particular to a biological carbonaceous composite adsorption material and a preparation method thereof.

Background technique

my country is a country lacking water resources, and eutrophication is one of the serious water pollution problems that my country faces. According to statistics, the eutrophication of major lakes in my country due to nitrogen and phosphorus pollution accounts for more than 56% of the statistical lakes. The eutrophication of water body is mainly because the nitrogen, phosphorus and other nutrients in the water body that can be used by algae are too much. Among them, phosphorus is the limiting factor of algae proliferation and the key nutrient that causes water body eutrophication. How to efficiently and cost-effectively remove phosphorus from water and solve the eutrophication of water has become the focus of current research work.

At present, the commonly used methods for phosphorus removal from wastewater at home and abroad mainly include dredging method, biological method, chemical method and adsorption method. The dredging method is expensive and complicated to manage, which is not conducive to the treatment of urban rivers and lakes and reservoirs; the biological method is greatly affected by the fluctuation of water quality, the phosphorus removal effect is unstable, and it is easily affected by external factors such as temperature, dissolved oxygen, and pH value; The phosphorus removal rate is high, but the operating cost is high, and a large amount of difficult-to-treat sludge is easily generated, causing secondary pollution. In contrast, the adsorption method has the advantages of less energy consumption, fast removal, stable phosphorus removal performance, and no secondary pollution. The key to the application of this method lies in the selection of good adsorbents, so as to satisfy the requirements of strong adsorption capacity, easy availability of materials, reusability and low cost.

However, the inorganic and organic fillers that are widely used in the market are difficult to meet the requirements of environmental friendliness. For example, ceramsite fillers, which are widely used in inorganic fillers, require a large amount of clay in the preparation process, which not only conflicts with the current tight agricultural production land, but also consumes a lot of energy during the sintering preparation process; while the raw materials prepared by organic fillers are mostly It comes from petroleum derivatives and is a non-renewable resource. In addition, the above-mentioned fillers are difficult to be biodegraded in the environment after being discarded, which not only poses a threat to the survival of living organisms in the surrounding environment, but also limits the reuse of the discarded fillers.

In the prior art, there are some technologies for preparing environmentally friendly fillers from biomass. For example, Chinese Patent No. 201610271844.9, published on June 22, 2016, discloses a patent document entitled a preparation method and application of a nanoparticle-loaded expanded particle carbon phosphorus removal adsorbent. A series of modifications such as surfactants and amino starch binders are carried out on biomass-like biomass, and a phosphorus removal adsorbent is prepared. The adsorbent has a high adsorption efficiency for phosphorus. However, the preparation process of the adsorbent is complicated, and it is difficult to achieve industrial application; another example : Chinese Patent Application No.: 201210100733.3, published on August 1, 2012, a patent application document entitled a composite ecological filler and its preparation method was disclosed, the composite ecological filler and its preparation method are steel slag Granules, mix evenly with anthracite and zeolite in a ratio of 1:1:1 as aggregate, then mix evenly with aggregate, high-strength aluminate cement, ferric oxide and water in a certain proportion, and place in a well-ventilated place to air dry. Get the desired product. The preparation method of the filler achieves the purpose of treating waste with waste, but there is still a big problem in the secondary utilization of the adsorption-saturated filler. For another example, the Chinese patent application number 201410430743.2, the application publication date was December 24, 2014. The patent discloses a patent document titled "Modified grapefruit peel adsorbent and its preparation method", which is modified based on the adsorption characteristics of cationic metal ions, and is not suitable for anionic metal ions. adsorption of phosphates. Others such as, Chinese Patent No. 200710118941.5, published on November 7, 2007, published a patent document entitled Preparation of a Novel Biofilm Carrier and Its Application in Industrial Wastewater Treatment, Chinese Patent Application No.: 200510014992.4 , published on May 31, 2006, published a patent application document entitled Controllable Degradable Cellulose-Based Microorganism Carrier Filler for Water Treatment and Preparation Method, and Chinese Patent No.: 200510019894.X, published on 2006 The name disclosed on June 28 is an application technology of a natural plant loofah hollow fiber material. The above research results have poor phosphorus adsorption effect, and the organic matter in these fillers is unstable in nature and is easily degraded by microorganisms in the water, making the fillers. Frequent replacement increases the load of organic matter in the water.

In the modification technology of phosphorus removal adsorbent, there are some modification methods with better phosphorus removal effect. For example, Chinese Patent No. 201310327020.5, published on October 23, 2013, discloses a patent document entitled a biological carbonaceous composite porous filler and its preparation method. The patent is to combine biomass such as rice straw and peanut shells. Carbonization, iron oxide loading and microwave modification were carried out to obtain the iron adsorbent. Although the iron adsorbent has a good adsorption and phosphorus removal effect, because the direct adsorption process is reversible, the adsorption effect is easily affected by surrounding environmental factors. Another example: Chinese Patent No. 201610234529.9, published on July 20, 2016, discloses a patent document called a phosphorus removal adsorbent of expanded graphite loaded composite metal and its preparation method, which is a composite metal for expanded graphite. Lanthanum and iron loading modification improves the adsorption efficiency of expanded graphite for phosphorus, but the utilization rate of metal ions is low, and the rare earth lanthanum is not easy to obtain, and the price is high. However, iron salts are rich in resources and cheap, and it is of great practical significance to further explore the modification method of loaded iron to improve the phosphorus removal efficiency and alleviate the degree of eutrophication of water bodies.

SUMMARY OF THE INVENTION

Aiming at the disadvantages of high operating cost, difficult operation and easy secondary pollution in the existing technology for removing phosphate from water, the present invention provides a method for preparing a biological carbonaceous composite adsorption material for removing phosphate from water, so as to achieve both The purpose of simple preparation process and low operation cost can be achieved, the adsorption capacity of phosphate can be improved, and an effective way for the utilization of waste resources can be provided at the same time.

In order to solve the above problems, the present invention adopts the following technical solutions.

The present invention is a preparation method of biological carbonaceous composite adsorption material for removing phosphate in water body, and the specific steps are as follows:

(1) grapefruit peel, orange peel are cut and dried to obtain biomass solids;

(2) heating and pyrolyzing the above biomass solids in anoxic or anaerobic conditions;

(3) cooling the biomass solid after the pyrolysis in step (2), then adding 1.2-1.5mol/L _FeSO4 solution, filtering and collecting the bio-carbon solid after shaking; adding the washed bio-carbon solid to 0.1- 0.3mol/L Na ₂ S ₂ O ₃ solution, filter and collect biochar solids after shaking; add the washed biocarbon solids to 0.01-0.03mol/L CTMAB solution, filter after shaking and wash with deionized water To neutral, bake at 80-100 ℃ for 5-6 hours;

(4) The mixture obtained in step (3) is washed with clean water and dried to obtain the biocarbon composite adsorption material.

Preferably, in step (1), the mass ratio of the grapefruit peel to the orange peel is 1-9:1. The biocarbon composite porous filler prepared in this range has high porosity and high adsorption efficiency.

Preferably, in the step (2), the pyrolysis temperature is 350-450°C. If the pyrolysis temperature is too high or too low, the adsorption efficiency will decrease significantly. The pyrolysis time was selected 20-30 minutes after many optimization experiments. During this time period, the biomass solids could be fully carbonized, and the carbonized products were easy to collect.

Preferably, in step (3), the shaking is performed in a water bath at 25-45°C.

Preferably, the biological carbonaceous composite adsorption material obtained by the above preparation method.

The biological carbonaceous composite adsorption material of the present invention is obtained by carbonization of biomass, loading of nano-iron and grafting of functional groups. The present invention utilizes the characteristics that the biological carbonaceous composite adsorption material has a large specific surface area, is easy to disperse in an aqueous solution, and has a large number of active sites on the surface to adsorb phosphate in water. The specific principle is speculated as follows:

Carbonized pomelo peel and carbonized orange peel have large specific surface area, and the adsorption characteristics of high reduction potential and high reaction rate after loading nano iron; continue to add CTMAB for modification, the ammonium end of CTMAB itself is related to biological The K ⁺ and Mg ²⁺ of the carbon itself undergo ion exchange, thereby introducing the carbon long-chain molecules of the surfactant. The long chain has more hydrophobic active sites, which can better adsorb the nano-iron particles on the surface.

The existence of phosphate in water is easily affected by environmental pH. Usually phosphorus in wastewater exists in the form of orthophosphate, polyphosphate and organophosphate, and under acidic conditions, polyphosphate can be hydrolyzed to orthophosphate. Therefore, in the process of phosphorus removal by adsorption of wastewater, the main focus is on orthophosphate. Orthophosphate will be ionized in water, and there are three forms of H ₂ PO ₄ ^- , HPO ₄ ^2- and PO ₄ ^3- . When the pH value of the water environment is 3.0-9.0, H ₂ PO ₄ ^- , HPO ₄ ^{2 -} is the main form of existence. When the phosphate reaches the inner ring layer on the surface of the adsorbent, it can be directly connected to the metal ion through coordination bonds (as shown in formulas 1 and 2); when the phosphate cannot reach the adsorption site to coordinate with it, the phosphate anion and the band The positively charged bio-carbon composite adsorption material will have electrostatic attraction in the solution (as shown in formulas 3 and 4), which promotes the comprehensive adsorption capacity of the bio-carbon composite adsorption material for phosphate ions, thereby achieving the purpose of removing phosphate from water. .

Fe—OH ^- +H ₂ PO ₄ ^- →Fe—H ₂ PO ₄ ^- +OH ^- (1)

Fe—OH ^- +HPO ₄ ^2- →Fe—HPO ₄ ^2- +OH ^- (2)

Fe—OH ₂ ⁺ +H ₂ PO ₄ ^- →Fe—OH ₂ ⁺ —H ₂ PO ₄ ^- (3)

Fe—OH ₂ ⁺ +HPO ₄ ^2- →Fe—OH ₂ ⁺ —HPO ₄ ^2- (4)

Compared with the prior art, the beneficial effects of the present invention are:

(1) The biological carbonaceous composite adsorption material of the present invention has a certain pore structure and surface chemical characteristics, and has a high removal rate of phosphate (orthophosphate and pyrophosphate) in water (when the P concentration is 10.0 mg/L, the removal rate is rate up to 95.50%). After the surface sewage with a phosphate concentration of 10mg/L is treated by the adsorption material of the present invention, the phosphate content of the water body reaches the surface water environmental quality standard (GB 3838-2002) Class V (≤0.4mg/L).

(2) The present invention comprehensively considers the economical cost of carbonization and the effect of carbonization, and through orthogonal optimization experiments of different carbonization parameters, it is concluded that the optimal temperature of carbonization is 350-450 ° C, and the carbonization time is 20-30 minutes, which improves the carbonization efficiency and saves money. economic cost.

(3) The biomass solids adopted in this method are grapefruit peel and orange peel, and these biomass raw materials are common substances in daily life, with wide sources and low cost. The saturated material can be used as phosphorus resource for secondary utilization after being filtered and collected. It not only realizes the resource utilization of waste, but also brings good social and economic benefits.

Description of drawings

Figure 1 is a schematic diagram of the preparation process of the present invention.

Fig. 2 is the scanning electron microscope picture before the modification of the product after the pomelo peel biomass carbonization in Example 1 of the present invention.

Fig. 3 is the scanning electron microscope picture after the product modification after the pomelo peel biomass carbonization in Example 1 of the present invention;

It can be seen from this figure that the surface structure of the modified composite adsorbent is more dispersed, mainly due to the insertion of CTMAB between the carbonized material layers.

Fig. 4 is the energy spectrum analysis figure before the product modification after the pomelo peel biomass carbonization in Example 1 of the present invention;

It can be seen from this figure that the main constituent elements of the carbonized product are C and O, and also contain trace elements such as Mg, Si, Cl and Ca.

Fig. 5 is the energy spectrum analysis diagram after product modification after pomelo peel biomass carbonization in Example 1 of the present invention;

It can be seen from this figure that the main elements of the modified carbonized product are C, O and Fe, of which w(Fe) is 18.44%, indicating that the surface of the modified adsorbent has been loaded with iron oxides, and also contains Na, Al and S and other trace elements.

Detailed ways

The present invention is further described in detail below with reference to the accompanying drawings, but is not intended to limit the present invention.

In the preparation of biomass materials in this preparation method, the commonality of the two biomass solids is used in each step. Therefore, only some materials and parameters are used as examples for preparation instructions in the examples. The preparation process is shown in Figure 1. .

Example 1

The pomelo peels were washed, air-dried, cut, heated and pyrolyzed in an oxygen-deficient environment in a muffle furnace, the pyrolysis temperature was 350°C, and the pyrolysis time was 30 minutes. The pyrolyzed material was cooled, then added to a 1.2 mol/L FeSO ₄ solution and shaken for 60 minutes. Filter and collect the carbonized biomass solids, add the washed carbonized biomass solids to a Na ₂ S ₂ O ₃ solution containing 0.1 mol/L, and shake for 40 minutes. After the solid was collected by filtration, it was added to a CTMAB solution containing 0.03 mol/L, shaken for 50 minutes, filtered and washed with deionized water until neutral, and dried at 80° C. for 6 hours to obtain the biological carbonaceous composite adsorption material 1.

Example 2

The orange peels were washed, air-dried, cut, heated and pyrolyzed in an oxygen-deficient environment in a muffle furnace, the pyrolysis temperature was 350°C, and the pyrolysis time was 30 minutes. The pyrolyzed material was cooled, then added to a 1.2 mol/L FeSO ₄ solution and shaken for 60 minutes. Filter and collect the carbonized biomass solids, add the washed carbonized biomass solids to a Na ₂ S ₂ O ₃ solution containing 0.1 mol/L, and shake for 40 minutes. After the solid was collected by filtration, it was added to a CTMAB solution containing 0.03 mol/L, shaken for 50 minutes, filtered and washed with deionized water until neutral, and dried at 100° C. for 5 hours to obtain the biological carbon composite adsorption material 2.

Example 3

After the grapefruit peel and orange peel were washed and air-dried, they were heated and pyrolyzed in an oxygen-free environment in a muffle furnace, the pyrolysis temperature was 450°C, and the pyrolysis time was 20 minutes. The pyrolyzed material was cooled, and the pomelo peel and orange peel were doped in a proportion of 9:1 by mass, and then added to a 1.5 mol/L FeSO ₄ solution and shaken for 60 minutes. Filter and collect the carbonized biomass solids, add the washed carbonized biomass solids to a Na ₂ S ₂ O ₃ solution containing 0.3 mol/L, and shake for 40 minutes. After the solid was collected by filtration, it was added to a CTMAB solution containing 0.03 mol/L, shaken for 50 minutes, filtered and washed with deionized water until neutral, and dried at 100° C. for 5 hours to obtain the biological carbonaceous composite adsorption material 3.

Example 4

Same as Example 3, the difference is that the pyrolysis time is 30 minutes.

Example 5

With embodiment 3, difference is that grapefruit peel and orange peel are 1:1 according to mass ratio.

Comparative ratio

After the grapefruit peel was washed and air-dried, it was heated and pyrolyzed in a muffle furnace, the pyrolysis temperature was 350°C, and the pyrolysis time was 30 minutes. The pyrolyzed material is cooled, and the carbonized biomass solid is collected, which is directly used as a phosphorus adsorption material after air-drying.

Phosphorus removal and adsorption tests were carried out on the biological carbonaceous adsorption materials prepared in the above-mentioned Examples 1-5 and Comparative Examples, respectively. The experiment used sodium dihydrogen phosphate (NaH ₂ PO ₄ ) to prepare phosphorus sewage, and its phosphate concentration was 5 mg/ L, 10 mg/L. The adsorption time was 15 hours, the water temperature was 35°C, and the shaking speed was 150 rpm.

Test data show that the adsorbent materials obtained in Examples 1-5 of the present invention have very significant removal efficiency for phosphate in sewage (as shown in Table 1). When the phosphate concentration was 5.0 mg/L and 10 mg/L, the removal rate of phosphorus by adsorbents 1-5 was significantly higher than that of the comparative adsorbents.

Table 1 Phosphorus removal experimental results of different embodiments

Example 1 Example 2 Example 3 Example 4 Example 5 Comparative ratio Removal rate (%) when the initial concentration of phosphorus is 5mg/L 96.20 92.40 97.80 98.20 94.60 51.00 Removal rate (%) when the initial concentration of phosphorus is 10mg/L 93.70 90.20 94.50 96.30 92.70 46.50

Claims (5)

1. a preparation method of the biological carbonaceous composite adsorption material that removes surface water phosphate, is characterized in that comprising the steps: (1) grapefruit peel, orange peel are cut and dried to obtain biomass solids; (2) heating and pyrolyzing the above biomass solids in anoxic or anaerobic conditions; (3) cooling the biomass solid after the pyrolysis in step (2), then adding 1.2-1.5mol/L _FeSO4 solution, filtering and collecting the bio-carbon solid after shaking; adding the washed bio-carbon solid to 0.1- 0.3mol/L Na ₂ S ₂ O ₃ solution, filter and collect bio-carbon solids after shaking; add the washed bio-carbon solids to 0.01-0.03 mol/L CTMAB solution, filter after shaking and wash with deionized water To neutral, bake at 80-100 ℃ for 5-6 hours; (4) The mixture obtained in step (3) is washed with clean water and dried to obtain the biocarbon composite adsorption material. 2. the preparation method of a kind of biological carbonaceous composite adsorption material that removes surface water phosphate as claimed in claim 1, is characterized in that, in step (1), the mass ratio of described grapefruit peel and orange peel is 1 -9:1. 3 . The method for preparing a biological carbonaceous composite adsorption material for removing phosphate from surface water as claimed in claim 1 , wherein in step (2), the pyrolysis temperature is 350-450° C., and the thermal The solution time is 20-30 minutes. 4 . The method for preparing a biological carbonaceous composite adsorption material for removing phosphate from surface water as claimed in claim 1 , wherein in step (3), the shaking is performed in a water bath at 25-45° C. 5 . . 5. The biological carbonaceous composite adsorption material obtained by the preparation method of the biological carbonaceous composite adsorption material for removing phosphate in surface water according to any one of claims 1-4.

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