CN116786086A - Method for preparing orange peel adsorbent by biological means, orange peel adsorbent and application thereof - Google Patents

Abstract

The invention discloses a method for preparing an orange peel adsorbent by biological means, an orange peel adsorbent and its application, and belongs to the field of medical technology. The preparation method includes: sampling; cooking; trypsin treatment in water bath; α-amylase treatment in water bath; enzyme-killing treatment; drying and grinding. By optimizing the adsorption conditions of modified navel orange peel residue, the present invention found that the adsorption effect is best when the addition amount is 0.15g, the particle size is 40 mesh, and the adsorption temperature is 26°C, and it fits well with the thermodynamic curve, indicating that the adsorption effect is the best. The adsorption process is a spontaneous endothermic process; in the modified navel orange peel adsorbent, the number of ‑OH, C＝O, C‑H, C＝N and other groups increases and participates in the adsorption process of nicotine, improving the material The adsorption effect; X-energy spectrum analysis shows that the content of C, O, H, and K elements in the modified navel orange peel increased, thereby enhancing the adsorption performance.

Description

Method for preparing orange peel adsorbent by biological means, orange peel adsorbent and application

Technical field

The present invention relates to the technical field of medical technology, and more specifically to a method for preparing an orange peel adsorbent by biological means, an orange peel adsorbent and its application.

Background technique

Nicotine is one of the main harmful substances in tobacco. It is an unpleasant-tasting, colorless and transparent oily liquid substance that is soluble in water, ethanol, chloroform, ether, etc. After nicotine enters the human body, it quickly reaches the brain and combines with nicotine acetylcholine receptors, causing the dopamine content in the brain to increase, creating a feeling of emptiness in the brain. After smokers increase the concentration through smoking and other methods, they relieve the emptiness caused by the rapid metabolism of nicotine and bring themselves a sense of relaxation and pleasure, which may eventually lead to addiction to smoking.

Cigarette filters are used to reduce smoke, tar and suspended particles produced during combustion. Filters are an important part of cigarette design. At present, the commonly used filter materials at home and abroad are acetate fiber, polyester fiber, activated carbon composite fiber, etc. Among them, acetate fiber is widely used in the tobacco industry because of its good adsorption effect, firm texture, high efficiency in trapping smoke tar, and beautiful configuration. It is an ideal cigarette filter material and one of the most popular materials in the world today. The main raw material for the production of cigarette filters. Once filter function evolved beyond their use purely as mouth-like components, cigarette filters evolved into smoke particle reduction mechanisms to reduce the amount of tar and nicotine inhaled. The three main functions of cigarette filters include direct interception, inertial compression and diffusion precipitation. The most common one is direct interception filter. Filtration is a complex process in which tar droplets separate from the smoke and adhere to the surface of the filter material when they reach it;

Navel orange, Latin name Citrus sinensis (L.) Osbeck, is an evergreen small tree of the family Sapindales, Rutaceae. Navel orange is an improved citrus variety cultivated in various countries around the world. At present, the suitable areas for navel oranges in my country are mainly in southern Jiangxi, southern Hunan, northern Guangxi and the Three Gorges Reservoir area. The main components of navel orange peels are carbonaceous materials such as water-insoluble dietary fiber and hemicellulose. They are loose and porous and have the ability to be made into biosorbents. Hard conditions for agents.

In recent years, the topic of using adsorption methods to reduce the amount of nicotine inhaled by people has attracted more and more attention. Activated carbon is a widely used adsorbent in adsorption methods. Traditional activated carbon mainly comes from wood, bamboo and coal. With the advancement of science and technology, people have begun to try to use other carbon-containing substances to prepare adsorbents. Some agricultural wastes contain a large amount of fiber. As potential activated carbon raw materials, researchers have tried to use leaves, rice husks, straw, sugarcane bagasse, soybean bagasse, etc. to prepare adsorbents to treat harmful substances.

Ganzhou City, Jiangxi Province is rich in navel oranges. In addition to eating navel oranges fresh, orange juice processing is the main way to increase the edible value of navel oranges. Whether it is traditional consumption or modern processing, it is inevitable to deal with the waste treatment problems caused by a large amount of navel orange peel residue. According to the nature that the main components of navel orange peel are loose and porous carbon-containing materials such as cellulose and hemicellulose, navel orange peel can be turned into treasure and take a sustainable development path. The development of navel orange peel biosorbent can become navel orange peel. Another important way of comprehensive utilization.

Contents of the invention

In order to solve the above technical problems, the present invention provides a method for preparing orange peel adsorbent by biofeeding means, as well as orange peel adsorbent and applications.

In order to achieve the above objects, the present invention adopts the following technical solutions:

A method for preparing orange peel adsorbent by biological means, including the following steps:

1) Sampling: Wash the collected navel orange peels, cut them into the size of bottle caps with scissors, place them in a drying box to dry and set aside;

2) Steaming: Put the navel orange peel into boiling water, take it out after steaming and set aside;

3) Trypsin treatment water bath: Put the navel orange peels treated in step 2) into a trypsin solution with a concentration of 100% in a water bath;

4) Alpha amylase treatment water bath: Put the navel orange peel treated in step 3) into an alpha amylase solution water bath to obtain navel orange peel residue;

5) Enzyme-killing treatment: Put the navel orange peel residue into the NaOH solution, stir thoroughly and let it sit for a period of time, then rinse with running water until neutral;

6) Drying: Place the rinsed navel orange peel residue flat in a drying box and dry to constant weight;

7) Grinding: Grind the dried navel orange peel and bag it for later use.

Preferably, the drying temperature in step 1) is 60°C.

Preferably, the cooking time in step 2) is 30 minutes.

Preferably, the concentration of the trypsin solution in step 3) is 4 mg/mL, and the water bath conditions are 60 min at 37°C.

Preferably, the concentration of the α-amylase solution in step 4) is 4-12 mg/mL; the water bath conditions are 60 min at 80°C.

Preferably, the concentration of the NaOH solution in step 5) is 0.1 mol/L, and the standing time is 20 minutes.

Preferably, the thickness of the tiles in step 6) is ≤1cm; the drying temperature is 100°C.

Another object of the present invention is to provide an orange peel adsorbent prepared by the above preparation method.

Another object of the present invention is to provide the application of fir orange peel adsorbent in purifying smoke nicotine.

Among them, the addition amount of the orange peel adsorbent is 0.15g, the particle size is 40 mesh, and the adsorption temperature is 26°C.

It can be seen from the above technical solutions that compared with the prior art, the present invention has the following beneficial effects:

1. Use Langmuir isotherm and Freundlich isotherm to fit the adsorption process of modified navel orange peel. It is found that the correlation coefficient R ² between the adsorption process and the Freundlich isotherm model reaches 0.999, indicating that the nicotine adsorption process of modified navel orange peel is consistent with The law described by the Freundlich isotherm model is multi-molecule layer multi-site adsorption;

2. Fit the data obtained from the test with the pseudo-first-order and pseudo-second-order kinetic curves respectively. The analysis shows that the correlation coefficient R ² between the chemically modified navel orange peel adsorption of nicotine and the pseudo-first-order kinetic model fitting reaches 0.9, indicating that This adsorption process is a mixed adsorption process with chemical adsorption as the main component and physical adsorption as the supplement;

3. Horizontal comparison: Under the same conditions, the optimal modified navel orange peel residue was compared with the four commonly used adsorbents, and the adsorption effect was found to be: modified navel orange peel residue > diatomite > activated carbon;

4. Adsorbent characterization analysis: Through elemental analysis, it was found that the contents of the four elements C, H, N, and S have changed in the original situation, after optimization treatment, and after adsorption, indicating that they play a role in adsorption; by FTIR infrared The analysis shows that in the modified navel orange peel adsorbent, the number of -OH, C=O, C-H, C=N and other groups increases and participates in the adsorption process of nicotine, improving the adsorption effect of the material; from the X-energy Spectral analysis shows that the content of C, O, H, and K elements in the modified navel orange peel increased, thereby enhancing the adsorption performance.

Description of the drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only These are embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on the provided drawings without exerting creative efforts.

Figure 1 is a schematic diagram of the nicotine adsorption device of the present invention;

Figure 2 is a schematic diagram of the nicotine standard curve of the present invention;

Figure 3 is a schematic diagram of the effect of α-amylase concentration on the adsorption effect of the present invention;

Figure 4 is a schematic diagram of the influence of five kinds of slag particle sizes on the adsorption effect of the present invention;

Figure 5 is a schematic diagram of the influence of different slag addition amounts on the adsorption effect of the present invention;

Figure 6 is a schematic diagram of the relationship between temperature and adsorption amount in the present invention;

Figure 7 is a schematic diagram of the thermodynamic curve of nicotine adsorption by modified navel orange peel of the present invention;

Figure 8 is a schematic diagram of the influence of nicotine concentration on the adsorption amount during adsorption according to the present invention;

Figure 9 is a schematic diagram of the Langmuir model of the present invention;

Figure 10 is a schematic diagram of the Freundlich model of the present invention;

Figure 11 is a schematic diagram showing the effect of adsorption time on adsorption amount according to the present invention;

Figure 12 is a schematic diagram of the quasi-first-order power curve of the present invention;

Figure 13 is a schematic diagram of the quasi-secondary power curve of the present invention;

Figure 14 is a comparison chart of the average adsorption effects of various materials on nicotine under different adsorption time conditions of the present invention;

Figure 15 is a Fourier transform infrared spectrum chart of the present invention;

Figure 16 is the X-ray diffraction pattern of navel orange peel residue of the present invention;

Among them, in Figure 1, A-the mouth of the rubber tube is connected to the cigarette, with the cigarette holder at the bottom; B-the air guide tube; C-the rubber stopper; D-the suction filter bottle.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

Example 1

2.1 Materials and equipment

2.1.1 Experimental materials

Navel orange peel: Pick up the peel from the navel oranges in the mountains and forests of Gannan, Longnan County, Jiangxi Province.

2.1.2 Experimental drugs

Experimental drugs are shown in Table 2.1.

Table 2.1 Experimental drugs

2.1.3 Experimental Instruments The main experimental instruments are shown in Table 2.2.

Table 2.2

2.2 Experimental method design

2.2.1 Draw the standard curve of nicotine solution

Improved preparation method of nicotine standard solution:

1) Use a pipette to take 0.1g of nicotine and dissolve it in 100ml of distilled water to prepare a mother solution with a concentration of 1000μg/mL;

2) Use a pipette to take 120ug of nicotine from the mother solution, add 5g NaOH, 0.02765g KMnO ₄ and adjust the volume to 250ml;

3) Use a pipette to take 190ug of nicotine from the mother solution, add 5g NaOH, 0.02765g KMnO ₄ and adjust the volume to 250ml;

4) Use a pipette to take 260ug of nicotine from the mother solution, add 5g NaOH, 0.02765g KMnO ₄ and adjust the volume to 250ml;

5) Use a pipette to take 330ug of nicotine from the mother solution, add 5g NaOH, 0.02765g KMnO ₄ , and adjust the volume to 250ml;

6) Use a pipette to take 400ug of nicotine from the mother solution, add 5g NaOH, 0.02765g KMnO ₄ and adjust the volume to 250ml;

7) Use a pipette to take 470ug of nicotine from the mother solution, add 5g NaOH, 0.02765g KMnO ₄ and adjust the volume to 250ml;

Pour the prepared solutions into six 250ml beakers, mark them, and put them in a 100°C water bath for 7.5 minutes. After cooling and filtering, measure the absorbance of the solutions with a spectrophotometer, and draw a nicotine solution standard curve.

2.2.2 Pretreatment of navel orange peel

Enzyme-assisted alpha-amylase method

1) Sampling: Wash the collected navel orange peels, cut them into the size of bottle caps with scissors, dry them in a drying oven at 60°C, weigh 100g, and divide them into 5 equal parts;

2) Steaming: Put each navel orange into boiling water and cook for 30 minutes.

3) Trypsin treatment water bath: Put the navel orange peel into a trypsin solution with a concentration of 4 mg/mL, and bathe in a water bath at a temperature of 37°C for 60 minutes.

4) Alpha amylase treatment water bath: Place each navel orange peel into an alpha amylase solution with a concentration of 4 mg/mL, 6 mg/mL, 8 mg/mL, 10 mg/mL, and 12 mg/mL, and place it at a temperature of 80°C Take a water bath for 60 minutes;

5) Enzyme-killing treatment: Put the navel orange peel residue into 0.1 mol/L NaOH solution, stir it thoroughly with a glass rod and let it stand for 20 minutes, then rinse it with flowing distilled water until it is neutral;

6) Drying: Lay the rinsed navel orange peel residue flat in a drying box with a thickness of no more than 1cm, and dry it to constant weight at 100°C;

7) Grinding: Use a small grinder to grind the dried navel orange peel and bag it for later use.

2.2.3 Nicotine analysis and measurement methods

There are many methods for analyzing and measuring nicotine. In addition to gravimetric and chemical volumetric methods, electrochemical methods, atomic absorption spectrometry, gas and liquid chromatography, etc. have all been used for the analysis of nicotine. The present invention adopts spectrophotometry to measure the content of nicotine, and ultraviolet spectrophotometry can be used for measurement.

The theoretical basis of the present invention is that nicotine will be oxidized by potassium permanganate into a green product under alkaline conditions. NaOH must be added first and then KMnO ₄ must be added, and the concentration of NaOH is 0.5 mol/L and the concentration of KMnO ₄ is 7×10 ^{- 4} mol/L, water bath at 100°C for 7.5 minutes. This green product has a maximum absorbance at a wavelength of 612nm. This absorption value is directly related to the nicotine content and can be used for trace analysis and determination.

a.. Assembly of adsorption device

The adsorption device is shown in Figure 1.

Note: The rubber tube at A is connected to the cigarette, with the cigarette holder at the bottom; B is the air tube; C is the rubber stopper for sealing; D is the filter bottle.

2.2.4 Adsorption experiment and determination and calculation of adsorption rate

1) Take out 1/3 of the acetate fiber in the cigarette filter and set aside for blank experiment.

2) Put a certain amount of navel orange peel residue into the filter paper cover with 1/3 of the length of the acetate fiber removed, and then put the remaining 2/3 of the length of the acetate fiber into the experimental cigarette.

4) Assemble the adsorption device, fix the cigarette on the adsorption end, close the water stop clamp, turn on the vacuum pump, wait until the vacuum pump pressure reaches 0.095MPa, open the water stop clamp, light the cigarette until it burns out, and the smoke enters the suction filter bottle (containing 150mL) distilled water) close the water stop clamp. After standing for 20 minutes, pour the solution into a volumetric flask, add 5gNaOH and 0.02765gKMnO ₄ in sequence, adjust the volume to 250ml, and shake well.

5) Put an appropriate amount of solution into a test tube, heat the mixture in a 100°C water bath for 7.5 minutes, cool to room temperature, filter with a filter membrane and add the filtrate to a colorimetric tube, and measure the absorbance at 612nm.

Calculation formula for the adsorption rate of navel orange peel residue to nicotine in cigarette smoke:

Adsorption rate = (M ₀ -M) × 100%/M ₀

Among them: M ₀ : is the total amount of nicotine in the device in the blank experiment;

M: is the mass of unadsorbed nicotine in each experiment (ug).

The nicotine content in each cigarette is as shown in the table below

Table 2.3 Nicotine content in cigarettes

2.2.7 Single factor experiment

Controlling other factors unchanged, multiple experiments were conducted to explore the influence of several important factors on the adsorption effect.

a. Effect of slag particle size on adsorption effect

Pass the optimally optimized navel orange peel residue through 8 mesh, 18 mesh, 40 mesh, 65 mesh, and 80 mesh sieves respectively to obtain navel orange peel residue of different mesh sizes. Take 0.1g of each and add it to the cigarette filter part. After the adsorption experiment, Measure the absorbance of each.

b. Effect of slag addition amount on adsorption effect

After obtaining the optimal slag particle size, add 0.05g, 0.1g, 0.15g, 0.2g, and 0.25g of navel orange peel slag to the cigarette filter part, and measure the absorbance after the adsorption test.

c. Effect of adsorption experiment temperature on adsorption effect

After the optimal slag addition amount is obtained, experiments are conducted at 20°C, 22°C, 24°C, 26°C, and 28°C, and then the absorbance is measured.

2.2.8 Adsorption isotherm

The adsorption isotherm is a mathematical formula that studies the relationship between adsorption amount and concentration under constant temperature conditions. It can be used to determine the nature of the adsorption phenomenon and study the adsorption capacity of the adsorbent for specific substances. The models used in this experiment are Langmuir and Freundlich isotherms.

The expression of Langmuir isotherm is: c/q＝c/Q _m +1/Q _m b

The expression of Freundlich isotherm is: q=K·Cn

Taking the logarithm of both sides of the above equation can turn it into a linear form: lgq=lgK+nlgc

Among them: c is the equilibrium concentration (mg/L); q is the equilibrium adsorption capacity (mg/g); _Qm is the saturated adsorption capacity (mg/g); b is the adsorption equilibrium constant, which represents the binding force of the adsorbent to the adsorbate. size. K and n are constants at a certain temperature.

1) Langmuir isotherm (monolayer adsorption theory): the adsorption sites are certain, and each adsorption site only adsorbs one molecule.

2) Freundlich isotherm (multi-molecular layer adsorption theory): It is an empirical model used to describe a heterogeneous adsorption system. If the surface properties of the adsorbent are uneven and there are many adsorption sites, it will conform to this adsorption model.

2.2.9 Adsorption power

Biosorbents include multiple transport processes when adsorbing nicotine, each of which may affect the reaction rate. In adsorption kinetics research, pseudo-first-order and pseudo-second-order kinetic equations are usually used to fit experimental data to analyze the change of adsorption performance with time to design an efficient adsorption system.

The expression of Lagergren's pseudo-first-order kinetic model is: lg(Qq)=lgQ-k ₁ t/2.303

The expression of the Ho pseudo-second-order kinetic model is: t/q＝1/(k ₂ ×Q)+t/Q

Among them: Q is the equilibrium adsorption capacity (mg/g); q is the adsorption capacity at adsorption t (mg/g); k ₁ is the first-order adsorption rate constant (min ^-1 ); k ₂ is the second-order adsorption rate constant ( g·mg ^-1 ·min ^-1 ).

2.2.10 Horizontal comparison

The modified navel orange peel biosorbent was prepared according to the optimal conditions, and the adsorption effects were compared with commercially available activated carbon, bamboo charcoal and diatomaceous earth under the same conditions.

Using the optimal processing conditions obtained from the orthogonal experiment, navel orange peel residue was produced, and experiments were conducted to compare the nicotine adsorption effects with activated carbon and acetate fiber under the same conditions.

2.2.11 Characterization analysis of modified navel orange peel residue

1)Elemental analyzer

The original navel orange peel, the optimized navel orange peel, and the adsorbed navel orange peel were subjected to elemental analysis, and the materials were wrapped in tin foil for analysis to obtain a comparison of C elements, N elements, and H elements, which facilitated qualitative analysis.

2)FTIR analysis

FTIR is the abbreviation of Fourier Transform Infrared Spectroscopy. FTIR is used to qualitatively analyze the original navel orange peel, optimized navel orange peel, and adsorbed navel orange peel. The peak changes of the functional groups of these three kinds of navel orange peel are studied to determine the navel orange peel. The adsorption mechanism of the adsorbent is chemical adsorption, physical adsorption, or physical and chemical mixed adsorption.

3)X-ray diffraction

Place the material into the groove, set θ to 10-50° for X-ray diffraction, create a diffraction pattern, and analyze the results.

The present invention uses an infrared spectrometer to study the changes in the peak values of each effective functional group before and after adsorption of modified navel orange peel residue, and then obtains the adsorption mechanism of the adsorbent.

3Results and analysis

3.1 Nicotine solution standard curve

The nicotine standard curve is shown in Figure 2.

The system obeys Beer's law in the concentration range of 0.4μg/mL~1.6μg/mL and has a correlation coefficient of 0.9996. The equation is y=0.8255x-0.1061.

3.2 Analysis of processing method results

Effect of α-amylase concentration on adsorption effect when trypsin-assisted α-amylase treatment of navel orange peels

It can be seen from Figure 3 that the adsorption rate of navel orange peel residue to nicotine first increases and then decreases with the increase of α-amylase concentration. When the α-amylase concentration is 6 mg/mL, the adsorption effect is the best, and the adsorption rate reaches 29.6%; When the α-amylase concentration is 12 mg/mL, the adsorption effect is the worst, and the adsorption rate is 23.5%. The yield of navel orange peel residue decreases with the increase of α-amylase concentration. When the α-amylase concentration is 4 mg/mL, the yield is the highest at 42.4%; when the α-amylase concentration is 12 mg/mL , the lowest yield, 36.8%. In summary, the adsorption effect of navel orange peel residue treated with 6 mg/mL α-amylase solution is relatively good.

3.4 Single factor processing results and analysis

3.4.1 Effect of slag particle size on adsorption effect

As can be seen from Figure 4, the adsorption rate of navel orange peel residues that pass through a 40-mesh sieve but not a 65-mesh sieve is the highest, reaching 42%, while the navel orange peel residues that pass a 8-mesh sieve but not a 18-mesh sieve have the lowest adsorption rate, which is 37.6%.

The variance analysis of the results of this experiment is shown in Table 3.3.

Table 3.3 Variance analysis table of adsorption rate under different slag particle size treatments

It can be inferred that there are significant level differences in the effects of different slag particle sizes on the adsorption rate. For further multiple comparisons, see Table 3.4.

Table 3.4 Effect of slag-free particle size treatment on adsorption rate (Duncan method)

It can be seen from Table 3.3 that navel orange peel materials with different particle sizes have a certain degree of influence on the nicotine adsorption rate. From Table 3.4, we can see that different mesh numbers have extremely significant differences in the adsorption rate of nicotine up to 1%. The adsorption rate of navel orange peel residue that passes through a sieve of 40 mesh but not 65 mesh is significantly greater than the adsorption rate of navel orange peel residue that passes a sieve of 65 mesh but not 80 mesh.

3.4.2 Effect of different slag addition amounts on adsorption effect

It can be seen from Figure 5 that as the amount of slag added increases, the adsorption rate of navel orange peel shows a trend of first increasing and then decreasing. When the amount of slag added is 0.15g, the adsorption rate is the largest, which is 42.2%.

Perform variance analysis on this experimental result, see Table 3.5.

Table 3.5 Variance analysis table of adsorption rate under different slag addition treatments

It can be inferred that the effects of different slag addition amounts on the adsorption rate are very significant. For further multiple comparisons, see Table 3.6.

Table 3.6 Effect of different slag amounts on adsorption rate (Duncan method)

It can be seen from Table 3.6 that different amounts of slag added have differences in the nicotine adsorption rate to a certain extent. The effects of different amounts of slag added on the nicotine adsorption rate have a very significant difference of 1%. When the amount of slag added is 0.15g, the nicotine adsorption rate is maximum.

3.5 Thermodynamic studies

It can be seen from Figure 6 that as the temperature increases, the amount of nicotine adsorbed by navel orange peel residue increases first and then levels off, indicating that this adsorption process is less affected by temperature.

The calculation formula of adsorption heat (ΔH) is:

InKC＝-ΔG ₀ /RT＝-ΔH ₀ /RT+ΔS ₀ /R

Among them: ΔG ₀ is the standard Gibbs free energy, the unit is kJ/mol; R is the thermodynamic gas constant, the value is 8.314J/(mol.K); T is the thermodynamic temperature, the unit is K; ΔH ₀ is the enthalpy of the reaction Variable, unit is kJ/mol; ΔS ₀ is entropy variable, unit is J/(mol.K); Kc is thermodynamic equilibrium constant; It is the mass concentration of nicotine gas molecules adsorbed on the adsorbent, in mg/L.

Table 3.7 Thermodynamic parameters of nicotine adsorption by modified navel orange peel

It can be seen from the table data that ΔH ₀ >0, so the adsorption process is an endothermic process, and ΔG ₀ <0, indicating that the reaction proceeds spontaneously. From Figure 7, it can be seen that the influence of temperature on the adsorption amount and the correlation coefficient of thermodynamic curve fitting R ² =0.9643, close to 1, indicating that the adsorption process is well fitted to the thermodynamic process and conforms to the laws of thermodynamics.

Draw an image with nicotine concentration on the horizontal axis and C/q on the vertical axis, and fit it to the Langmuir isotherm;

In Figure 9, the straight line at 22°C is y ₁ =0.5919x+0.8305 R ² =0.9374

The straight line at 24°C is y ₂ =0.6286x+0.8044 R ² =0.9719

The straight line at 26°C is y ₃ =0.7197x+0.7734 R ² =0.9819

Draw with lgC as the horizontal axis and lgQ as the ordinate.

In Figure 10, the 22°C straight line is y ₁ =0.9103x-0.0923 R ² =0.9984

The straight line at 24°C is y ₂ =0.899x-0.0913 R ² =0.9995

The straight line at 26°C is y ₃ =0.8831x-0.1028 R ² =0.9995

Table 3.8 Adsorption kinetic parameters of modified navel orange peel

The Langmuir isotherm and Freundlich isotherm models were used to fit the nicotine adsorption process of the optimal modified navel orange peel. As shown in Figure 8, Figure 9, Figure 10, and Table 3.8, it can be seen that the correlation coefficient R ² between the adsorption process and the Freundlich isotherm model fitting reaches 0.999, indicating that the adsorption process of nicotine by chemically modified navel orange peel is in line with the rules described by the Freundlich isotherm model. It is multi-molecule layer multi-site adsorption.

3.7 Adsorption power

In the kinetic test of nicotine adsorption by navel orange peel, plot time t as the horizontal axis and lg(Q-q) as the vertical axis, and fit it with the pseudo-first-order kinetic equation; plot time t as the horizontal axis and t/q Fit the image on the vertical axis to the pseudo-second-order kinetic equation. The results are shown in Figure 11:

Table 3.9 Kinetic parameters of nicotine adsorption by modified navel orange peel

The data obtained from the experiment were fitted with pseudo-first-order and pseudo-second-order kinetic curves to analyze the change process of nicotine concentration over time. From the analysis of Figures 11, 12, 13 and Table 3.9, it can be seen that the correlation coefficient R ² between the nicotine adsorption data of chemically modified navel orange peel residue and the pseudo-second-order kinetic model fitting reaches 0.9973, which is close to 1. It shows that the adsorption process follows the law of the pseudo-second-order kinetic model, and the experimental process is a mixed adsorption with chemical adsorption as the mainstay and physical adsorption as the supplement.

3.8 Horizontal comparison experiment

Comparing the adsorption effects of diatomaceous earth, activated carbon and cellulose acetate, the average adsorption effect of each material on nicotine under the same conditions is shown in Figure 14.

It can be seen from Figure 14 that the average adsorption effect of optimized navel orange peel residue on nicotine is significantly better than that of other materials; and under the conditions of adsorption time of 20s, 25s, 30s, and 35s, the adsorption effects of the remaining four different types of materials are From large to small, they are diatomite, activated carbon, optimized navel orange peel residue, and cellulose acetate; when the adsorption time is 40 seconds, the order of adsorption effect is diatomite, activated carbon, cellulose acetate, and unoptimized navel orange peel residue. That is, under the condition of 40s adsorption time, the adsorption effect of cellulose acetate on nicotine is better than that of unoptimized navel orange peel residue.

The variance analysis of nicotine adhesion rates for different materials is shown in Table 3.10.

Table 3.10 Variance analysis table of nicotine adsorption rates of different materials

It can be inferred that the effects of different materials on the adsorption rate are very significant. Further multiple comparisons are made, see Table 3.11.

Table 3.11 Analysis of nicotine adsorption rates of different materials (Duncan method)

It can be seen from Table 3.10 that during the adsorption process of nicotine, different materials and different adsorption times will have a significant impact on the adsorption effect. At the same time, the interaction between the two factors of material and time will also affect the adsorption effect. It can be seen from Table 3.11 that the change The adsorption effect of navel orange peel on nicotine is significantly better than the other four materials.

3.9 Elemental analysis

The original navel orange peel, optimized navel orange peel, and adsorbed navel orange peel were analyzed by an elemental analyzer. The obtained element contents are as shown in Table 3.12.

Table 3.12 Element content in original navel orange peel, optimized navel orange peel, and adsorbed navel orange peel

From Table 3.12, we can see that the optimized C, H, N, and S element contents have all changed, indicating that the optimization process may cause changes in the number of polar groups such as C=N groups and -COOH in the material. The change plays an important role in the adsorption of nicotine. The H element content of the optimized navel orange peel residue increases, indicating that the optimization treatment increases the number of -OH and other groups in the material, which plays a great role in adsorbing nicotine.

3.10 Fourier transform infrared spectroscopy

Analysis of Figure 15 shows that there is -OH stretching peak vibration around the wave number of 3446.04cm ^-1 , indicating that the activity of -OH has changed. It can be seen that the absorbance peak transmittance of the optimized navel orange peel at -OH has significantly decreased. The peak is tilted to the left, which indicates that -OH plays a role in the adsorption process after optimization in number and activity. In addition, there are also peak changes in groups such as C=O, CH, and COC, indicating that these groups also play a role in the adsorption process of nicotine. It can be seen that chemical functional groups play a role in the adsorption process, which is an adsorption process dominated by chemical adsorption.

3.11X-ray diffraction

From the analysis of the spectrum, it can be seen that there is almost no change in the diffraction peak position of the original navel orange peel and the optimized navel orange peel. However, by calculating the amount of X-ray crystallization, it can be concluded that the optimized navel orange peel has a stable physical structure, and its X-ray diffraction pattern As shown in Figure 16:

In Figure 16: a represents after adsorption, b represents the original navel orange peel residue, and c represents the original navel orange peel residue;

The analysis chart shows that the position of the characteristic diffraction peak of navel orange peel without treatment, treatment and adsorption has not changed significantly. There is a strong characteristic diffraction peak at 2θ=22.5°, which represents the crystallization region of cellulose. It can be seen that the diffraction peak of the navel orange peel after adsorption is the largest, followed by the optimization, and the original is the lowest, indicating that the stability of the physical structure of the navel orange peel is: adsorption navel orange peel > optimized navel orange peel > original navel orange peel. This shows that after chemical modification, the crystallinity of navel orange peel is enhanced and it has better physical structure stability.

It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that these entities or operations are mutually exclusive. any such actual relationship or sequence exists between them. Furthermore, the terms "comprises," "comprises," or any other variations thereof are intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus that includes a list of elements includes not only those elements, but also those not expressly listed other elements, or elements inherent to the process, method, article or equipment.

Each embodiment in this specification is described in a progressive manner. Each embodiment focuses on its differences from other embodiments. The same and similar parts between the various embodiments can be referred to each other. As for the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple. For relevant details, please refer to the description in the method section.

The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be practiced in other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A method for preparing orange peel adsorbent by biological means, which is characterized in that it includes the following steps: 1) Sampling: Wash, cut, and dry the collected navel orange peels for later use; 2) Steaming: Put the navel orange peel into boiling water, take it out after steaming and set aside; 3) Trypsin treatment water bath: Put the navel orange peels treated in step 2) into a trypsin solution with a concentration of 100% in a water bath; 4) Alpha amylase treatment water bath: Put the navel orange peel treated in step 3) into an alpha amylase solution water bath to obtain navel orange peel residue; 5) Enzyme-killing treatment: Put the navel orange peel residue into the NaOH solution, stir thoroughly and let it sit for a period of time, then rinse with running water until neutral; 6) Drying: Place the rinsed navel orange peel residue flat in a drying box and dry to constant weight; 7) Grinding: Grind the dried navel orange peel and bag it for later use. 2. A method for preparing orange peel adsorbent by biological means according to claim 1, characterized in that the drying temperature in step 1) is 60°C. 3. A method for preparing orange peel adsorbent by biological means according to claim 1, characterized in that the cooking time in step 2) is 30 minutes. 4. A method for preparing orange peel adsorbent by biological means according to claim 1, characterized in that the concentration of the trypsin solution in step 3) is 4 mg/mL, and the water bath condition is a water bath at 37°C. 60 minutes. 5. A method for preparing orange peel adsorbent by biological means according to claim 1, characterized in that the concentration of the α-amylase solution in step 4) is 4-12 mg/mL; the conditions of the water bath are Water bath at 80°C for 60 minutes. 6. A method for preparing orange peel adsorbent by biological means according to claim 1, characterized in that the concentration of the NaOH solution in step 5) is 0.1 mol/L, and the standing time is 20 min. 7. A method for preparing orange peel adsorbent by biological means according to claim 1, characterized in that the thickness of the tile in step 6) is ≤ 1 cm; the drying temperature is 100°C. 8. An orange peel adsorbent, characterized in that it is prepared by the method of preparing an orange peel adsorbent by biological means according to any one of claims 1 to 7. 9. Application of an orange peel adsorbent as claimed in claim 8 in purifying smoke nicotine. 10. The application of an orange peel adsorbent in purifying smoke nicotine according to claim 9, characterized in that the addition amount of the orange peel adsorbent is 0.15g, the particle size is 40 mesh, and the adsorption temperature is 26℃.