CN115626645A - Application of passion fruit shell-based activated carbon in sewage treatment and super capacitor - Google Patents

Application of passion fruit shell-based activated carbon in sewage treatment and super capacitor Download PDF

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CN115626645A
CN115626645A CN202211276954.6A CN202211276954A CN115626645A CN 115626645 A CN115626645 A CN 115626645A CN 202211276954 A CN202211276954 A CN 202211276954A CN 115626645 A CN115626645 A CN 115626645A
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activated carbon
passion fruit
based activated
adsorption
fruit shell
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曾艳萍
黄齐林
林洪
潘静
揭楚玉
杨菊芳
王国莉
李旭
张春浩
刘佳慧
金瑞雪
申艳
彭光平
熊启莎
邓源园
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Yuxi Normal University
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/30—Active carbon
    • C01B32/312—Preparation
    • C01B32/342—Preparation characterised by non-gaseous activating agents
    • C01B32/348—Metallic compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/20—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising free carbon; comprising carbon obtained by carbonising processes
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/30—Active carbon
    • C01B32/312—Preparation
    • C01B32/318—Preparation characterised by the starting materials
    • C01B32/324—Preparation characterised by the starting materials from waste materials, e.g. tyres or spent sulfite pulp liquor
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • C02F1/283—Treatment of water, waste water, or sewage by sorption using coal, charred products, or inorganic mixtures containing them
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/30—Electrodes characterised by their material
    • H01G11/32—Carbon-based
    • H01G11/34—Carbon-based characterised by carbonisation or activation of carbon
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/13—Energy storage using capacitors

Abstract

The invention discloses application of passion fruit shell-based activated carbon in sewage treatment and a super capacitor, wherein passion fruit shells are used as raw materials, the activated carbon is prepared by adopting a potassium hydroxide activation method, preparation reagents and instruments are simple, industrial production can be realized, the prepared activated carbon has excellent adsorption performance and electrochemical performance, and when the initial concentration of methylene blue solution is 200 mg.L ‑1 When the active carbon is adsorbed for 30min, the adsorption quantity of the passion fruit shell-based active carbon is 941mg g ‑1 The adsorption capacity of the commercially available wood activated carbon is 191mg g ‑1 The adsorption amount is 5 times of that of the commercially available activated carbon; at the currentDensity of 1 A.g ‑1 In this case, the specific discharge capacity of the activated carbon prepared by the oxidation with 10% nitric acid is 8 times that of the commercially available activated carbon.

Description

Application of passion fruit shell-based activated carbon in sewage treatment and super capacitor
Technical Field
The invention belongs to the technical field of biomass waste utilization, and particularly relates to application of passion fruit shell-based activated carbon in sewage treatment and a super capacitor.
Background
China is the first agricultural kingdom in the world, and livestock and poultry manure, melon peels, fruit shells and other wastes generated in the production process of agriculture and animal husbandry in China each year exceed 40 hundred million tons; the biomass waste is not sufficiently treated and utilized, the environmental pollution is very serious, and the biomass waste is an important problem which influences the environment and restricts the development of economy and society;
the passion fruit is rich in nutrition, food made of the passion fruit is popular among people, and a great amount of passion fruit shells are produced every year by passion fruit processing enterprises, cannot be effectively utilized and can only be discarded, so that resource waste is caused.
Disclosure of Invention
In order to solve the technical problems, the passion fruit shell is used as a raw material, a chemical activation method is utilized, KOH is used as an activating agent to prepare high-performance activated carbon, and the passion fruit-based activated carbon is used for treating methylene blue in sewage and is used for preparing a super capacitor;
in order to achieve the technical purpose, the invention is realized by the following technical scheme:
the preparation method of the passion fruit-based activated carbon comprises the following steps:
s1: selecting high-quality passion fruit shells, cleaning, drying, cooling, grinding, crushing and sieving;
s2: drying the ground passion fruit shell base powder in a drying oven, cooling and putting into a dryer for later use;
s3: weighing the sieved and dried passion fruit shell powder, putting the passion fruit shell powder into a tube furnace, and heating the passion fruit shell powder in a nitrogen environment to carbonize the passion fruit shell powder; cooling, grinding and crushing after carbonization, and putting into a dryer for storage;
s4: mixing the carbon powder obtained in the step S3 with a KOH activating agent, grinding the mixture into paste, putting the paste mixture into a tubular furnace, and heating and activating the mixture in a nitrogen environment;
s5: after the activated carbon heated and activated in the S4 is cooled to room temperature, washing and filtering the activated carbon to be neutral by using hydrochloric acid and ultrapure water;
s6: drying the activated carbon washed and filtered to be neutral in the step S5, cooling, grinding and sieving to obtain passion fruit shell-based activated carbon;
preferably, the passion fruit shell-based activated carbon is subjected to 10% of HNO 3 Oxidation treatment;
preferably, the drying temperature in the S1 is 100-105 ℃, the drying is carried out for 8 hours, and the materials are sieved by a 80-mesh sieve;
preferably, the drying temperature in the S2 is 100-105 ℃, and the drying is carried out for 5 hours;
preferably, the temperature rise rate in the S3 is 5 ℃ min -1 Heating to 450-500 ℃; carbonizing for 2 hours;
preferably, the mass ratio of the carbon powder to the KOH activator in the S4 is 1:2; at 5 ℃ min -1 Activating for 2 hours at the temperature rising rate until the temperature is 800 ℃;
preferably, the concentration of hydrochloric acid in S5 is 1 mol.L -1 ；
Preferably, the drying temperature in S6 is 105 ℃.
Applying the prepared passion fruit shell-based activated carbon to sewage treatment and a super capacitor;
preferably, the passion fruit-based activated carbon is used for adsorbing methylene blue in sewage; the pH of the adsorption acid-base environment is =11.
The invention has the beneficial effects that:
the invention adopts passion fruit shells as raw materials, adopts a potassium hydroxide activation method to prepare the activated carbon, has simple preparation reagent and instrument, can implement industrial production, and has excellent adsorption performance and electrochemical performance when the initial concentration of methylene blue solution is 200 mg.L -1 When the active carbon is adsorbed for 30min, the adsorption quantity of the passion fruit shell-based active carbon is 941mg g -1 The adsorption capacity of the commercially available wood activated carbon is 191mg g -1 The adsorption amount is 5 times of that of the commercially available activated carbon; at a current density of 1 A.g -1 In this case, the specific discharge capacity of the activated carbon prepared by the oxidation with 10% nitric acid is 8 times that of the commercially available activated carbon.
Drawings
FIG. 1 is a process for the preparation of a passion fruit shell-based activated carbon;
FIG. 2 is a Fourier transform infrared spectrum of different materials;
FIG. 3 is a standard graph;
FIG. 4 is the effect of pH on adsorption performance;
FIG. 5 is a plot of the initial concentration of methylene blue on the adsorption performance (A) as well as Langmuir (B) and Freundlich (C) isothermal adsorption fit curves;
FIG. 6 is a relationship (A) between the adsorption amount of activated carbon to methylene blue and time, and a quasi-first-order (B) and a quasi-second-order (C) kinetic model of methylene blue adsorption of passion fruit shell-based activated carbon;
FIG. 7 shows the position of the passion fruit shell-based electrode at 3 mol. L -1 Cyclic voltammogram (a is 5 mv. S) at different scanning rates in KOH electrolyte -1 Cyclic voltammogram at a scanning rate, b is 50mv s- 1 Cyclic voltammogram at the scan rate);
FIG. 8 is the specific capacitance of different electrodes at different current densities;
FIG. 9 is a graph of cycle life for electrodes of different materials cycled 100 times;
fig. 10 is a graph of cycle life for electrodes of different materials cycled 100 times.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
Passion fruit-based activated carbon adsorption mechanism research
1) Passion fruit shell-based activated carbon oxidation treatment
Dividing the prepared passion fruit shell-based active carbon powder into 5 equal parts, taking four parts, and soaking the four parts in HNO with the mass concentration of 5%, 10%, 15% and 20% respectively 3 Standing the solution for 24h, washing the solution to be neutral by using a large amount of ultrapure water after the solution is fully oxidized, and drying and sieving the solution by using a 200-mesh sieve to obtain a required sample. The samples were named separately, unoxidized passion fruit shell activated carbon was denoted as PFAC, and nitric acid oxidized activated carbons of different mass concentrations were denoted as 5PFACN, 10PFACN, 15PFACN, 20PFACN, respectively.
2) Infrared characterization of Passion fruit shell-based activated carbon
The surface functional groups of the passion fruit shell-based activated carbon were measured using a fourier transform infrared spectrometer (FT-IR). Adopting KBr tabletting method, mixing appropriate amount of unoxidized and oxidized passion fruit-based active carbon with different nitric acid concentrations with KBr, grinding, tabletting under 10MPa with KBr as background, and tabletting at 4000-400cm -1 Range of wavelengthsAnd (4) internal scanning.
3) Drawing of standard curve
Accurately weighing 0.2066g of methylene blue (with water content of 1.70%) and fixing the volume in a 50mL volumetric flask to prepare 200 mg.L -1 Methylene blue standard stock solution. Transferring 0.25 mL, 0.75 mL, 1.25 mL, 1.75 mL and 2.25mL of methylene blue standard stock solution respectively, fixing the volume in a 50mL colorimetric tube, and preparing the solutions with the concentration of 1, 3, 5, 7, 9 and 11 mg.L respectively -1 Methylene blue solution of (2). The absorbance of the methylene blue solution was scanned over a wavelength range of 800-500nm to determine the maximum absorption wavelength. And measuring the absorbance of the solution with different concentrations at the wavelength of 664nm, and drawing a standard curve.
4) Adsorption experiment method
Preparing methylene blue solution with a certain concentration, and adjusting the pH value by using HCl or NaOH solution. Weighing 0.0200g of passion fruit shell-based active carbon in a 250mL conical flask, accurately transferring 100.00mL of methylene blue solution with a certain concentration into the conical flask, sealing with a sealing film, oscillating for a certain time at a certain temperature, taking out the filtering film, performing suction filtration, diluting, and measuring the absorbance at 664 nm.
5) Results
a. Infrared spectrogram analysis of tamarind shell-based activated carbon
FIG. 2 is an infrared image of nitric acid oxidized passion fruit shell based activated carbon with different mass concentrations, and it can be seen from the image that the peak positions of PFAC, 5PFACN, 10PFACN, 15PFACN and 20PFACN are basically similar, and the peak of PFAC is 3435.94cm -1 Possibly an-OH characteristic absorption peak or an N-H stretching vibration characteristic absorption peak which passes through HNO 3 3374.95cm of 5PFACN after oxidation -1 The position should be-OH characteristic absorption peak or N-H stretching vibration characteristic absorption peak, 2914.13cm -1 May be-CH 3 1587.66cm -1 The point may be N = N telescopic vibration absorption peak, 1165.60cm -1 An absorption peak at which stretching vibration of C-O-C or-N-N ≡ N may occur, 3330.00cm for 10PFACN, 15PFACN, 20PFACN -1 Should be-OH characteristic absorption peak or N-H stretching vibration characteristic absorption peak, 1579.47cm -1 The point may be N = N telescopic vibration absorption peak, 1229.24cm -1 In which the vibration may be C-O-C or-N-N ≡ NAbsorption peak. The infrared spectrum peak positions of five materials of PFAC, 5PFACN, 10PFACN, 15PFACN and 20PFACN are close, and the functional groups which are possibly added to the carbon after oxidation are ether groups and diazo bonds. The peaks of the 5PFACN are disordered and may be related to its oxidation concentration. In summary, the 10PFACN oxidized carbon has the best effect.
b. Drawing of standard curve
In the concentration c (mg. L) of methylene blue solution -1 ) The absorbance A was plotted and the results are shown in FIG. 3. And (3) carrying out linear fitting on the curve to obtain a linear regression equation as follows: a =0.1223c-0.018, correlation coefficient R2=0.9990, indicating a good linear relationship of c-a over the experimental concentration range.
c. Effect of pH on activated carbon adsorption of methylene blue
Figure 4 is a graph of the effect of pH on the adsorption of methylene blue by passion fruit shell based activated carbon. As can be seen from the graph, when the pH is less than 11, the curve shows a clear rising trend, and the adsorption quantity gradually increases along with the increase of the pH; maximum adsorption at pH = 11; at pH > 11, the adsorption capacity begins to decrease. The main reasons are: methylene blue belongs to cationic compounds, and methylene blue is easily adsorbed by negatively charged groups on the surface of an adsorbent. Passion fruit shell-based active carbon surface hydroxyl and other groups and OH - The action is carried out to have negative charge, and methylene blue is dissolved in water and then ionized to generate colored ions with positive charge. When the pH is lower, the passion fruit shell-based activated carbon is surrounded by protons, which is not beneficial to adsorbing methylene blue; when the pH increases, H + The concentration is reduced, more active sites can be provided for methylene blue adsorption, and the adsorption effect is enhanced. But with OH in solution - Increase of OH - And the adsorption sites attract methylene blue to compete and increase with passion fruit shell-based active carbon adsorption sites through electrostatic attraction, and the adsorption capacity is reduced.
d. Passion fruit shell-based activated carbon adsorption mechanism research
Isothermal adsorption study
Fig. 5 (a) shows the adsorption amount of passion fruit shell-based activated carbon for methylene blue at different initial concentrations. As can be seen from the figure, the initial concentration was 200 to 400 mg.L -1 When the change is carried out, the adsorption capacity of the passion fruit shell-based activated carbon to the methylene blue is gradually increased along with the increase of the initial concentration of the methylene blue. The main reasons are that the concentration is increased, the driving force of the methylene blue adsorbate is increased, the interaction with the activated carbon is enhanced, the effective collision probability is increased, and the adsorption capacity is increased. When the concentration of the methylene blue solution is more than 500 mg.L -1 Then, the adsorption isotherm tends to be flat along with the increase of the concentration, namely the adsorption capacity tends to be saturated, and the maximum adsorption capacity is 1225.68 mg.g -1 Approaching the theoretical saturated adsorption capacity. The passion fruit shell-based activated carbon has a good adsorption effect on methylene blue.
In order to further explore the adsorption mechanism of the passion fruit shell-based activated carbon on methylene blue, the adsorption experimental data of the graph shown in the figure 5 (A) are fitted by using Langmuir (1) and Freundlich (2) isothermal adsorption models, and the graphs are shown in figures 5 (B) and (C). The fitting parameters are shown in table 1.
Figure BDA0003895821950000071
Figure BDA0003895821950000072
In the formula: qe is the amount of adsorption (mg. G) -1 ) (ii) a qm is the maximum adsorption (mg. G) -1 ) (ii) a ce is the concentration of methylene blue solution at adsorption equilibrium (mg. L) -1 ) (ii) a b is Langmuir isothermal adsorption equation constant (L. Mg) -1 ) (ii) a Freundlich constant (mg. L) of KF relating to adsorption Capacity -1 ) (ii) a n is an index relating to adsorption capacity.
As can be seen from Table 1, the correlation coefficient R of the equation fitted by the Langmuir model 2 =0.9994 is greater than the correlation coefficient (R) of the Freundlich model equation fit 2 = 0.9289) and is very close to 1. Therefore, langmuir can better fit the adsorption of the passion fruit shell-based active carbon to methylene blue, and the adsorption of the methylene blue on the surface of the passion fruit shell-based active carbon is the adsorption of a monomolecular layer. The theoretical maximum adsorption capacity of the passion fruit shell-based active carbon to methylene blue is 1250mg g -1 。
TABLE 1 isothermal adsorption model parameters for the adsorption of methylene blue by Passion fruit shell-based activated carbon
Figure BDA0003895821950000081
Study of adsorption kinetics
Fig. 6 (a) is a graph of the effect of adsorption time on the ability of passion fruit shell-based activated carbon to adsorb methylene blue. As can be seen from the figure, when the adsorption time is less than 40min, the adsorption amount of the passion fruit shell based active carbon on methylene blue is increased rapidly along with the increase of time; after 40min, the change of the adsorption quantity with time is slowed down, and the adsorption reaches saturation after 60min, namely, the adsorption is balanced. The main reasons are that the surface active sites of the passion fruit shell-based activated carbon are more at the beginning of adsorption, the adsorption sites are reduced along with the increase of the adsorption time, and the change of the adsorption quantity is slowed down, which explains that the active sites on the surface of the adsorbent are one of the important factors influencing the adsorption rate of the adsorbent.
In order to research the adsorption kinetic process of the passion fruit shell-based activated carbon on methylene blue, the experimental process of the passion fruit shell-based activated carbon on methylene blue, which changes along with time, is fitted by adopting the methods of the quasi-primary and quasi-secondary kinetic models (3) and (4), the reaction mechanism is presumed, and various parameters are calculated, and the fitting result is shown in fig. 6 (B) and (C). The kinetic parameters of the passion fruit shell based activated carbon for adsorbing methylene blue are calculated and shown in table 2.
ln(q e -q t )＝ln q e -k 1 t (3)
Figure BDA0003895821950000082
In the formula: q. q.s e To balance the adsorption amount (mg. G) -1 )；q t The amount of adsorption at time t (mg. G) -1 )；k1(min -1 )、k 2 (g·mg -1 ·min -1 ) Is a rate constant.
As can be seen from Table 2, the correlation coefficient R2 of the quasi-secondary kinetic model was 0.9998, which is higher than the correlation coefficient R2 of the quasi-primary kinetic model (0.9495), and the equilibrium adsorption amount fitted thereto was 1000.00mg g -1 And experimental data(990.19mg·g -1 ) The method is very close, the relative error is 0.99%, and the result shows that the adsorption process of the passion fruit shell-based activated carbon to methylene blue is more consistent with a quasi-secondary kinetic model.
TABLE 2 kinetic parameters of the adsorption of methylene blue by Passion fruit shell-based activated carbon
Figure BDA0003895821950000091
Thermodynamic analysis of adsorption
Table 3 is the effect of temperature on the adsorption of methylene blue by passion fruit shell based activated carbon. The adsorption amount of the passion fruit shell-based active carbon for adsorbing methylene blue at the temperature of 303, 313 and 323K is considered, and the delta G in the adsorption process is calculated according to the formula (5-7) θ 、ΔH θ 、ΔS θ Values, see table 3:
ΔG θ ＝ΔH θ -TΔS θ (5)
Figure BDA0003895821950000092
Figure BDA0003895821950000093
in the formula: r is a gas constant (J. Mol) -1 ·K -1 ) (ii) a T is the thermodynamic temperature (K); k is a thermodynamic constant; c. C a And c e The concentrations of the passion fruit shell-based active carbon and methylene blue (mg. L) in the solution in adsorption equilibrium are respectively -1 )；
TABLE 3 thermodynamic parameters of the adsorption of methylene blue by the passion fruit shell-based activated carbon
Figure BDA0003895821950000094
As can be seen from Table 3, the enthalpy change Δ H in the adsorption process θ >0, the adsorption process is an endothermic reaction, and the temperature is increased to be beneficial to the passion fruit shell-based activated carbon to react with methyleneAdsorption of the basic blue; entropy is a measure of the degree of disorder (disorder) of the system, the entropy of reaction Δ S θ >0, indicating that the adsorption is facilitated by increasing the chaos degree of a solid-liquid interface; gibbs free energy change delta G θ And < 0, indicating that the passion fruit shell-based activated carbon adsorbs methylene blue as a spontaneous process.
e. The adsorption performance of the passion fruit shell-based active carbon is compared with that of the commercially available wood active carbon
When the initial concentration of the methylene blue solution is 200 mg.L -1 When the active carbon is adsorbed for 30min, the adsorption quantity of the passion fruit shell-based active carbon is 941mg g -1 The adsorption capacity of the commercially available wood activated carbon is 191mg g -1 The passion fruit shell-based active carbon has far better adsorption performance on methylene blue of printing and dyeing fuels than the commercially available wood active carbon.
Example 2
Electrochemical performance research of super capacitor
1) Cyclic voltammetry analysis
FIGS. 7 (a) and 7 (b) show that the 5mv s of the supercapacitor assembled by five materials of PFAC, 5PFACN, 10PFACN, 15PFACN and 20PFACN respectively -1 And 50mv s -1 According to the cyclic voltammetry curve under the scanning rate, no redox peak appears in the graph, and the result shows that the super capacitor prepared from the acid-angle shell-based activated carbon is an electric double layer capacitor, stores energy under the electrostatic action, and does not generate redox reaction. As the scan rate increases, the extent to which the curve deviates from a rectangular shape increases, indicating that the stability and symmetry of the capacitor is diminished.
2) Constant current charge and discharge analysis
FIG. 8 (a) shows the current density of five electrodes at different current densities (1, 2, 5, 10, 20A g) -1 ) The specific capacitance of the multiplying power performance curve prepared by the change trend of the specific capacitance is in a descending trend along with the increase of the current density, mainly because OH in the electrolyte solution is in the descending trend when the current density is increased - Less transfer occurs between the electrode material and the interface, resulting in less utilization of the active species in the electrode, resulting in a decrease in specific capacitance. By contrast, 5PFACN can maintain a larger specific capacitance at high current density, and 10PFACN can have a larger specific capacitance if charged and discharged at lower current density. FIG. 8 (b) is a graph ofThe bar chart of the specific capacitance content of the commercial activated carbon can be seen from the chart and is 1 A.g -1 In this case, the specific discharge capacity of the activated carbon prepared by the oxidation with 10% nitric acid is 8 times that of the commercially available activated carbon.
3) Cycle performance
FIG. 9 shows five electrode materials of PFAC, 5PFACN, 10PFACN, 15PFACN and 20PFACN at a current density of 5A g -1 According to a cycle life curve obtained by 100 cycles, after the cycle, the specific capacitance of 5PFACN and 10PFACN can be maintained to be about 97%, and is hardly reduced compared with the unoxidized cycle life, and the electrochemical performance of the electrode material is reduced probably due to the larger oxidation concentration of 15PFACN and 20PFACN, so that the graph shows that the acid-corner shell-based activated carbon electrode super capacitor has ideal double-layer characteristics, and the method has important significance for the practical application of the super capacitor.
4) AC impedance
Fig. 10 is an ac impedance spectrum of passion fruit shell-based activated carbon. The low-frequency part is close to vertical, which shows that the ionic diffusion internal resistance of the electrolyte is small and the capacitance performance is good. The Warburg-type curve (slope 1) of the intermediate frequency region is the resistance to diffusion of ions from the electrolyte to the surface of the electrode material. The high frequency region represents the charge transfer process at the electrode/electrolyte interface, and the smaller the semicircle, the smaller the resistance, the more favorable the charge transfer. Impedance to the surface of the electrode material. The high frequency region represents the charge transfer process at the electrode/electrolyte interface, and the smaller the semicircle, the smaller the resistance, and the more favorable the charge transfer.
Conclusion
1. The analysis of the adsorption mechanism of the passion fruit shell-based active carbon on methylene blue shows that: the adsorption effect is the best when the pH is =11, the Langmuir isothermal adsorption model and the quasi-second order kinetic equation can better fit the adsorption process, and the adsorption process is spontaneous, endothermic and tends to be disordered. The product provides theoretical basis for better utilization of the activated carbon to treat the printing and dyeing wastewater.
2. When the initial concentration of the methylene blue solution is 200 mg.L -1 When the active carbon is adsorbed for 30min, the adsorption quantity of the passion fruit shell-based active carbon is 941mg g -1 The adsorption capacity of the commercially available wood activated carbon is 191mg g -1 The adsorption amount is 5 times of that of the commercially available activated carbon.
3. The passion fruit shell-based activated carbon is used as an electrode material of a capacitor, and the prepared electrode is 3 mol.L -1 KOH is used as electrolyte, and cyclic voltammetry, constant current charge and discharge, cyclic performance and alternating current impedance are measured under a three-electrode system. The results show that 1 A.g -1 The specific discharge capacity of the activated carbon prepared by oxidizing 10% nitric acid is 8 times that of the commercially available activated carbon under the current density.

Claims (10)

1. The preparation method of the passion fruit-based activated carbon is characterized by comprising the following steps of:
s1: selecting high-quality passion fruit shells, cleaning, drying, cooling, grinding, crushing and sieving;
s2: putting the ground passion fruit shell base powder into an oven for drying, cooling and putting into a dryer for later use;
s3: weighing the sieved and dried passion fruit shell powder, putting the passion fruit shell powder into a tube furnace, and heating the passion fruit shell powder in a nitrogen environment to carbonize the passion fruit shell powder; cooling, grinding and crushing after carbonization, and putting into a dryer for storage;
s4: mixing the carbon powder obtained in the step S3 with a KOH activating agent, grinding the mixture into paste, putting the paste mixture into a tubular furnace, and heating and activating the mixture in a nitrogen environment;
s5: after the activated carbon heated and activated in the S4 is cooled to room temperature, washing and filtering the activated carbon to be neutral by using hydrochloric acid and ultrapure water;
s6: and (4) drying the activated carbon which is washed and filtered to be neutral in the S5, cooling, grinding and sieving to obtain the passion fruit shell-based activated carbon.
2. The preparation method of passion fruit-based activated carbon according to claim 1, wherein the passion fruit shell-based activated carbon is subjected to 10% HNO 3 And (5) oxidation treatment.
3. The preparation method of passion fruit-based activated carbon according to claim 1, wherein the drying temperature in S1 is 100-105 ℃, the drying is carried out for 8h, and the product is sieved by a 80-mesh sieve.
4. The method for preparing a passion fruit-based activated carbon as claimed in claim 1, wherein the drying temperature in S2 is 100 to 105 ℃ and the drying time is 5 hours.
5. The method of making passion fruit-based activated carbon as defined in claim 1, wherein the rate of temperature rise in S3 is 5 ℃. Min -1 Heating to 450-500 ℃; carbonizing for 2h.
6. The preparation method of a passion fruit-based activated carbon as claimed in claim 1, wherein the mass ratio of carbon powder to KOH activator in S4 is 1:2; at 5 ℃ min -1 Activating for 2 hours at the temperature of 800 ℃ under the temperature rising rate.
7. The method for producing a passion fruit-based activated carbon as claimed in claim 1, wherein the concentration of hydrochloric acid in S5 is 1mol · L -1 。
8. The method for preparing a passion fruit-based activated carbon as claimed in claim 1, wherein the drying temperature in S6 is 105 ℃.
9. The preparation method of passion fruit-based activated carbon as claimed in claim 1, wherein the prepared passion fruit shell-based activated carbon is applied to sewage treatment and supercapacitors.
10. The method for preparing a passion fruit-based activated carbon as claimed in claim 9, wherein the passion fruit-based activated carbon is used for adsorbing methylene blue in sewage; the pH of the adsorption acid-base environment is =11.
CN202211276954.6A 2022-10-18 2022-10-18 Application of passion fruit shell-based activated carbon in sewage treatment and super capacitor Pending CN115626645A (en)

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Citations (1)

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CN107311172A (en) * 2017-07-18 2017-11-03 桂林电子科技大学 A kind of passion fruit shell base porous carbon materials and its preparation method and application

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107311172A (en) * 2017-07-18 2017-11-03 桂林电子科技大学 A kind of passion fruit shell base porous carbon materials and its preparation method and application

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