CN113588754B - All-solid-state ion selective electrode modified based on single-walled carbon nanotube composite porous pine cone biochar and preparation method thereof - Google Patents
All-solid-state ion selective electrode modified based on single-walled carbon nanotube composite porous pine cone biochar and preparation method thereof Download PDFInfo
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Abstract
The invention provides an all-solid-state ion selective electrode modified by composite porous pine cone biochar based on a single-walled carbon nanotube and a preparation method thereof. The all-solid-state ion-selective electrode includes: the conductive substrate, the porous pine cone biochar solid transduction layer modified on the outer surface of the conductive substrate, the single-walled carbon nanotube layer modified on the outer surface of the porous pine cone biochar solid transduction layer, and the ion selective membrane layer modified on the outer surface of the single-walled carbon nanotube layer; the thickness of the porous pine cone biochar solid transfer layer is 0.05-0.1 mm; the thickness of the single-wall carbon nanotube layer is 0.05-0.1 mm; the thickness of the ion selective film layer is 0.05-0.15 mm. The all-solid-state ion selective electrode has better ion-electron conversion efficiency, conductivity and capacitance performance, good hydrophobicity and potential stability; the sensitivity, stability and repeatability of ion detection can be greatly improved.
Description
Technical Field
The invention belongs to the technical field of electrochemical analysis, and particularly relates to an all-solid-state ion selective electrode modified based on single-walled carbon nanotube composite porous pine cone biochar and a preparation method thereof.
Background
The ion selective electrode is an important electrochemical sensor, and the detection principle is based on the fact that the relation between the potential response of a sensitive membrane and the activity of a substance to be detected conforms to the Nernst equation. Compared with other sensors, the ion selective electrode attracts attention due to the advantages of simple principle, easy preparation, convenient operation, high selectivity, rapid response, low price, nondestructive detection, wide application range and the like, and is widely applied to the fields of environmental monitoring, clinical diagnosis, biomedical analysis and the like. Compared with the traditional glass ion selective electrode containing internal filling liquid, the all-solid-state ion selective electrode is firmer and more durable, has no problems of external leakage of the internal filling liquid and the like, is easy to maintain, has a simple structure, is easy to miniaturize, and has wider application prospect.
The all-solid-state ion selective electrode mainly comprises three parts, namely a conductive substrate, a solid transfer layer, an ion selective polymer membrane and the like, wherein the solid transfer layer plays a main electron transfer role, different transfer layer materials have difference in the application of the ion selective electrode, the current commonly used transfer layer materials comprise three types, namely conductive polymers, novel carbon nano materials and metal nano materials, and the conductive polymer materials are the materials which are firstly applied to the electrode transfer layer, but are not widely applied due to low redox capacitance and conductivity; the carbon nano material is easy to synthesize, and has better electrochemical performance, physical property and chemical stability; the metal nano material has high conductivity, large specific surface area and excellent performance, is mainly synthesized by precious metal materials such as gold, silver and the like, so the manufacturing cost is high and the application range is limited.
Disclosure of Invention
Based on the defects in the prior art, the invention has the first aim of providing the all-solid-state ion selective electrode modified by the composite porous pine cone biochar based on the single-walled carbon nanotube; the second purpose of the invention is to provide a preparation method of the all-solid-state ion selective electrode.
The purpose of the invention is realized by the following technical means:
in one aspect, the invention provides an all-solid-state ion selective electrode modified based on single-walled carbon nanotube composite porous pine cone biochar, which comprises:
the conductive substrate, the porous pine cone biochar solid transduction layer modified on the outer surface of the conductive substrate, the single-walled carbon nanotube layer modified on the outer surface of the porous pine cone biochar solid transduction layer, and the ion selective membrane layer modified on the outer surface of the single-walled carbon nanotube layer;
the thickness of the porous pine cone biochar solid transfer layer is 0.05-0.1 mm; the thickness of the single-wall carbon nanotube layer is 0.05-0.1 mm; the thickness of the ion selective membrane layer is 0.05-0.15 mm.
The traditional glass ion selective electrode containing internal filling liquid has the defects of poor anti-interference capability, unstable potential, large size and the like; in the all-solid-state ion selective electrode, the porous pine cone biochar is used as a solid transfer layer, a KOH activating agent is selected to activate a carbon material, so that the purpose of pore forming is achieved, and the all-solid-state ion selective electrode has a large specific surface area and a large pore diameter, so that the specific surface area and the porosity of the material are improved, and the capacitance performance is improved; moreover, the porous pine cone biochar has good chemical stability, reversible ion electronic signal conversion performance and better hydrophobicity, increases the contact area with an ion selective membrane, can provide an ideal non-polarizable interface and has high self-exchange current density. In addition, the invention also modifies a single-walled carbon nanotube layer on the solid transfer layer to improve the conductivity and the hydrophobicity of the electrode transfer layer, so that the electrode transfer layer has good hydrophobicity, good conductivity and small resistance.
In the above all-solid-state ion-selective electrode, preferably, the conductive substrate includes a graphite electrode, a glassy carbon electrode, a platinum electrode, or a gold electrode, but is not limited thereto.
In the above all-solid-state ion-selective electrode, preferably, the raw material components for preparing the ion-selective membrane layer include:
a solute and a solvent with 4-8 times of the total mass of the solute;
the solute comprises the following components in percentage by mass as 100 percent: 0.5 to 4 percent of ion carrier, 25 to 35 percent of polymer, 60 to 70 percent of plasticizer and 0.5 to 1.5 percent of cation exchanger.
In the above all-solid-state ion-selective electrode, preferably, the solvent includes tetrahydrofuran, but is not limited thereto.
In the above all-solid-state ion-selective electrode, preferably, the ionophore is a non-conductive high molecular polymer.
In the above all-solid-state ion-selective electrode, preferably, the ionophore includes one or more of calcium ionophore, potassium ionophore and sodium ionophore, but is not limited thereto.
In the above all-solid-state ion-selective electrode, preferably, the calcium ionophore includes ETH 1001, 10, 19-bis [ (octadecylcarbamoyl) methoxyacetyl ] -1,4,7,13, 16-pentaoxa-10, 19-diazacycloheneicosane, (-) - (R, R) -N, N ' -bis- [11- (ethoxycarbonyl) undecyl ] -N, N ', 4, 5-tetramethyl-3, 6-dioxaoctane-diamide, diethyl N, N ' - [ (4R,5R) -4, 5-dimethyl-1, 8-dioxo-3, 6-dioxaoctylene ] bis (12-methylaminolaurate), N, N, N ', N ' -tetrakis [ cyclohexyl ] diglycolic acid diamide, N, N ', N ' -bis (11-ethoxycarbonyl) undecyl ] -N, N, N ', 4, 5-tetramethyl-3, 6-dioxaoctylene ] bis (12-methylaminolaurate), N, N, N ', N ' -tetrakis [ cyclohexyl ] diglycolic acid diamide, N, N, N ' -bis (2-methyl-dimethylol) or N, N, N, N ' -bis (5-bis (ethoxycarbonyl) undecane, N, N ' -dioxan, N, N, S, N, N, N, S, one or more of N, N, N ', N' -tetracyclohexyl-3-oxaglutaramide and tert-butyl-calix [4] arene tetrakis [2- (diphenylphosphoryl) ethyl ether ], but are not limited thereto.
In the above all-solid-state ion-selective electrode, preferably, the potassium ionophore includes one or more of valinomycin, 4-tert-butyl-2, 2,14, 14-tetraethyl-substituted-2 a,14a, dioxacalix [4] arene-tetra-tert-butyl tetraacetate, bis [ (benzo-15-crown-5) -4 ' -ylmethyl ] pimelate, and 2-dodecyl-2-methyl-1, 3-propanediylbis [ N- [5 ' -nitro (benzo-15-crown-5) -4 ' -yl ] carbamate ], but is not limited thereto.
In the above-described all-solid-state ion-selective electrode, preferably, the sodium ionophore includes N, N ', N "-triheptyl-N, N ', N" -trimethyl-4, 4 ', 4 "-propylidene tris (3-oxabutanamide), N ' -dibenzyl-N, N ' -diphenyl-1, 2-phenylenedioxydiethylamide, N ' -tetracyclohexyl-1, 2-phenylenedioxydiethylamide, 2,3:11, 12-bisdecahydronaphthalenyl-16-coronanic acid-5, 4-octadecylmethyl-N, N ' -tetracyclohexyl-1, 2-phenylenedioxydiethylamide, bis [ (12-crown ether-4) methyl ] -2-dodecyl-2-propanedioic acid dimethyl ester, One or more of bis [ (12-crown-4) methyl ]2, 2-didodecylmalonate and 4-tert-butylcalix [4] arene-tetraacetic acid tetraethyl ester, but not limited thereto.
In the above all-solid-state ion-selective electrode, preferably, the polymer includes one or more of polyvinyl chloride (PVC), acrylic polymer, and urethane rubber, but is not limited thereto.
In the above all-solid-state ion-selective electrode, preferably, the plasticizer includes one or more of o-nitrooctyl ether (o-NPOE), aromatic ether, carboxylic ester, and phosphoric ester, but is not limited thereto. The performance of the high polymer material can be improved and the strength of the membrane can be enhanced by adopting the o-nitrooctyl ether.
In the above all-solid-state ion-selective electrode, preferably, the cation exchanger includes sodium tetrakis [3, 5-bis (trifluoromethyl) benzene ] borate (natfbb) and/or potassium tetrakis [3, 5-bis (trifluoromethyl) benzene ] borate (KTFPB), but is not limited thereto. The sodium [3, 5-bis (trifluoromethyl) benzene ] borate can avoid interference of lipophilic anions in the solution on an ion carrier, improve the sensitivity of an electrode and improve the ion-electron conversion efficiency.
In the above all-solid-state ion selective electrode, preferably, in the porous pine cone biochar solid-state conducting layer, the preparation method of the porous pine cone biochar comprises:
cleaning pine cone with ethanol, grinding into powder with a mortar, and heating and carbonizing the pine cone powder in argon atmosphere to obtain carbonized black pine cone charcoal powder;
uniformly mixing and stirring carbonized pine cone charcoal powder and an aqueous solution of an activating agent, and then transferring the mixture to a vacuum freeze dryer to remove water to obtain a solid mixture;
and heating the solid mixture in argon atmosphere for activation, centrifuging the cooled product to be neutral, and drying in vacuum to obtain the porous pine cone biochar.
The invention adopts mature pine cone on pine, which has loose material, high carbon content and wide distribution and is a good raw material for preparing the porous carbon material. Firing at high temperature under nitrogen atmosphere by adding different masses of activators, which contain mainly C, O, N element. By regulating the proportion of KOH/pine cone biochar and the preparation temperature in the preparation process, the morphology structure of the porous carbon can be effectively regulated, and the electrochemical performance of the ion selective electrode can be further regulated.
In the above all-solid-state ion-selective electrode, preferably, the pine cone is ground into powder having a particle size of 100 mesh.
In the above all-solid-state ion-selective electrode, preferably, the activator includes one or more of potassium hydroxide, sodium hydroxide, zinc chloride, potassium carbonate, and sodium carbonate, but is not limited thereto.
In the above all-solid-state ion-selective electrode, the aqueous solution of the activator preferably has a concentration of 10% to 80% by mass, preferably 45% by mass.
In the above all-solid-state ion-selective electrode, the freeze-drying time of the vacuum freeze-dryer is preferably 36 hours.
In the above all-solid-state ion selective electrode, preferably, the mass ratio of the carbonized pine cone charcoal powder to the activator is 1: (1-10).
In the all-solid-state ion selective electrode, the temperature for heating and carbonizing the pine cone powder in the argon atmosphere is preferably 700-1000 ℃, and is preferably 900 ℃; the carbonization time is 120-240 min; the heating rate is 2-5 ℃/min.
In the all-solid-state ion selective electrode, preferably, the temperature for heating and activating the solid mixture in an argon atmosphere is 700-900 ℃, and preferably 800 ℃; the activation time is 120-240 min, preferably 180 min; the heating rate is 2-5 ℃/min, preferably 5 ℃/min.
On the other hand, the invention also provides a preparation method of the all-solid-state ion selective electrode, which comprises the following steps:
dispersing porous pine cone biochar in a mixed solution of water and ethanol and performing ultrasonic treatment to obtain a porous pine cone biochar dispersion solution; dripping the porous pine cone biochar on the surface of an electrode substrate, drying to form a film, and forming a porous pine cone biochar solid transfer layer on the surface of the electrode substrate;
depositing and decorating a single-walled carbon nanotube layer on the outer surface of the porous pine cone biochar solid-state transfer layer by adopting an electrophoretic electrodeposition method;
dripping solution of an ion selective film layer on the surface of the single-wall carbon nanotube layer in a vacuum drying box, and drying to form a film so as to form the ion selective film layer; finally preparing the all-solid-state ion selective electrode.
In the above preparation method, preferably, in the mixed solution of water and ethanol, the volume ratio of water to ethanol is (1-4): 1.
in the above preparation method, preferably, the method for depositing and modifying a single-walled carbon nanotube layer on the outer surface of the solid-state transduction layer of the porous pine cone biochar by using an electrophoretic electrodeposition method comprises:
dispersing the single-walled carbon nanotube in a mixed solution of concentrated nitric acid and concentrated sulfuric acid, performing ultrasonic treatment, washing to be neutral, dispersing the treated single-walled carbon nanotube in water, performing ultrasonic treatment to obtain a uniformly dispersed solution, taking an electrode modified with the porous pine cone biochar solid transfer layer as an anode and a platinum wire as a cathode, and applying voltage to two ends of the electrode, so that the single-walled carbon nanotube layer is modified on the electrode modified with the porous pine cone biochar solid transfer layer.
In the above preparation method, preferably, in the mixed solution of concentrated nitric acid and concentrated sulfuric acid, the volume ratio of concentrated nitric acid to concentrated sulfuric acid is 1: (1-5); preferably 1: 3. The molar concentration of the concentrated nitric acid is 14 mol/L; the molar concentration of the concentrated sulfuric acid is 18 mol/L.
In the preparation method, the voltage of the electrophoresis is preferably 2-3V, and preferably 2.5V; the distance between the anode and the cathode is 1.5-2.5 mm; preferably 2 mm.
The carbon material of the electric double layer capacitor has poor hydrophobicity and mechanical strength, and in order to overcome the influence of a water layer on the all-solid-state ion selective electrode and improve the conductivity of the electrode material, the invention further introduces a single-wall carbon nanotube layer by an electrophoretic electrodeposition method, so that the hydrophobicity and the conductivity are good.
The invention has the beneficial effects that:
in the all-solid-state ion selective electrode based on the porous pine cone biochar, the porous pine cone biochar solid transfer layer can greatly improve the contact area between the conductive substrate and the ion selective membrane, further improve the ion and electron conversion efficiency of the electrode, and simultaneously reduce the interference of external factors on the detection performance of the electrode. Compared with the traditional conductive polymer electrode, the solid conductive layer of the invention has the advantages that the introduction of the porous pine cone biochar solid conductive layer greatly improves the performance indexes of the electrode such as stability, sensitivity, anti-interference capability and the like; moreover, a single-wall carbon nanotube layer is introduced between the solid-state transduction layer and the ion selective membrane, so that the interference of a water layer is further reduced, and the electric conductivity of the electrode is improved. The all-solid-state ion selective electrode has better ion-electron conversion efficiency, conductivity and capacitance performance, good hydrophobicity and good potential stability; the sensitivity, stability and repeatability of ion detection can be greatly improved. The pine cone biochar-based porous carbon ion selective electrode disclosed by the invention is low in preparation cost, simple to operate and easy for miniaturization and commercial production.
Drawings
FIG. 1 is a schematic structural diagram of an all-solid-state ion-selective electrode according to the present invention.
FIG. 2 is a graph showing the response characteristics of all-solid-state calcium ion-selective electrodes prepared in example 1 of the present invention at different KOH mass ratios.
FIG. 3A is an SEM representation of an unactivated porous pine cone biochar material of the present invention.
FIG. 3B shows an activation ratio of 1:3 SEM characterization of porous pine cone biochar material.
Fig. 4 is a water layer test experiment of the all-solid-state calcium ion-selective electrode prepared in example 1 of the present invention and the all-solid-state calcium ion-selective electrode prepared in comparative example 1.
FIG. 5 is a plot of cyclic voltammetry scans for all-solid-state calcium ion-selective electrodes of different KOH mass ratios prepared in example 1 of the present invention.
Fig. 6 is a water layer test experiment of the all-solid-state calcium ion-selective electrode prepared in example 1 of the present invention and the all-solid-state calcium ion-selective electrode prepared in comparative example 2.
Detailed Description
The technical solutions of the present invention will be described in detail below in order to clearly understand the technical features, objects, and advantages of the present invention, but the present invention is not limited to the practical scope of the present invention. The starting materials used in the following examples are all conventionally commercially available unless otherwise specified.
Example 1:
the embodiment provides an all-solid-state calcium ion selective electrode modified by single-walled carbon nanotube composite porous pine cone biochar, as shown in fig. 1, the all-solid-state calcium ion selective electrode comprises:
the conductive substrate, the porous pine cone biochar solid-state transduction layer modified on the outer surface of the conductive substrate, the single-walled carbon nanotube layer modified on the outer surface of the porous pine cone biochar solid-state transduction layer and the ion selective membrane layer modified on the outer surface of the single-walled carbon nanotube layer;
the thickness of the porous pine cone biochar solid-state transfer layer is 0.1 mm; the thickness of the single-wall carbon nanotube layer is 0.1 mm; the thickness of the ion selective membrane layer is 0.1 mm.
The embodiment also provides a preparation method of the all-solid-state ion selective electrode, which comprises the following steps:
(1) preparing porous pine cone biochar:
cleaning and drying pine nuts, grinding the pine nuts into powder of 100 meshes by using a mortar, carbonizing the powder for 3 hours at 900 ℃ in a tube furnace under the atmosphere of argon to form black biochar, heating at the speed of 5 ℃/min, and mixing 0.1g of porous pine nut biochar with a mass ratio of 1: 1. 1: 3. 1: 5 KOH (i.e., KOH mass: 0.1g, 0.3g and 0.5g, respectively) was mixed in the solution, excess water was removed by freeze-drying for 36h, the mixture was activated in a tube furnace at 800 ℃ for 3h under nitrogen atmosphere at a heating rate of 5 ℃/min, the product was cooled to room temperature and centrifuged with deionized water to neutrality, and dried in a vacuum oven at 70 ℃ for 12h to obtain porous pine cone biochar.
(2) Preparation of a solution of the calcium ion-selective membrane layer:
100mg (2.4% of N, N, N ', N' -tetracyclohexyl-3-oxaglutaramide (ETH129), 30.6% of polyvinyl chloride, 65.8% of o-nitrooctyl ether and 1.2% of sodium tetrakis [3, 5-bis (trifluoromethyl) benzene ] borate in percentage by mass) of solutes are dissolved in 700. mu.L of tetrahydrofuran solvent, and the solution of the calcium ion selective membrane layer is prepared by ultrasonic treatment for 60 min.
(3) Preparing an all-solid-state calcium ion selective electrode:
dispersing the porous pine cone biochar prepared in the step (1) in deionized water to obtain a 4mg/mL porous pine cone biochar aqueous solution; then 10 mu L of porous pine cone biochar water solution is dripped on the surface of a glassy carbon electrode, drying is carried out under an electrode baking lamp, and the drying is repeated twice, so that a layer of porous pine cone biochar solid transfer layer with the coating thickness of 0.1mm is obtained;
dispersing 0.1g of single-walled carbon nano-tube in a mixed solution of concentrated nitric acid (14mol/L) and concentrated sulfuric acid (18mol/L) (volume ratio is 1: 3), ultrasonically washing to be neutral, then dispersing the treated single-walled carbon nano-tube in water, ultrasonically treating to obtain a uniformly dispersed 2mg/mL solution, taking an electrode modified with the porous pinecone biochar solid transfer layer as an anode and a platinum wire as a cathode, wherein the distance between the anode and the platinum wire is 2mm, and applying a voltage of 2.5V to two ends of the electrode, thereby modifying the outer surface modified with the porous pinecone biochar solid transfer layer with a single-walled carbon nano-tube layer with the thickness of 0.1 mm.
And (3) dripping 10 mu L of the solution of the ion selective membrane layer prepared in the step (2) on the surface of the conductive polymer layer in the nitrogen atmosphere, drying at room temperature for 24 hours to form the 0.1mm ion selective membrane, and finally preparing the all-solid-state calcium ion selective electrode.
When in use, the all-solid-state calcium ion selective electrode is placed into 0.1mol/L calcium chloride solution to be soaked for at least 12h for activation.
Potential response test experiment:
the potential response test of the all-solid-state calcium ion selective electrode prepared in the embodiment specifically comprises the following steps:
the activated all-solid-state calcium ion selective electrodes are sequentially arranged at 10 by an open-circuit potential method-5M、10-4M, 1mM, 10mM and 100mM calcium chloride solutions are respectively tested for 200s, the potential change is recorded, the experimental result is shown in figure 2, A, B, C, D in figure 2 respectively shows that the potential change is not activated, the activation ratio is 1: 1. 1:3 and 1: 5 potential response diagram.
As can be seen from fig. 2: the potential of the transduction layer materials of different KOH activation ratios increased with increasing ion concentration, and the KOH activation ratio was 1:3, the material has better potential response, which shows that the calcium ion selective electrode taking the porous pine cone biochar with a proper KOH activation ratio as a solid state transfer layer has good ion-electron conversion efficiency.
Comparative example 1:
this comparative example provides an all-solid-state calcium ion-selective electrode, which is different from example 1 in that carbonized porous pine cone biochar, which is not activated with KOH (fig. 3A) based on the preparation method of porous pine cone biochar of example 1, is used as a solid-state transduction layer to compare the effects after KOH activation (fig. 3B).
As can be seen from a comparison of fig. 3A and 3B: the KOH activated pinecone carbon material has obvious pore-forming phenomenon.
And (4) water layer comparison test:
the all-solid-state calcium ion selective electrode prepared in example 1 of the present invention and the all-solid-state calcium ion selective electrode prepared in comparative example 1 were subjected to water layer testing, and the electrodes were immersed in 1mM CaCl2The solution was immersed for 2h, then 1mM NaCl solution for 2h, and finally 1mM CaCl2And continuously recording the potential response of the electrode after 8h of solution, and comparing the potential change before and after the electrode is immersed in the NaCl solution to verify the reversibility and water layer interference resistance of the electrode.
As can be seen from fig. 4, the all-solid-state calcium ion selective electrode prepared in example 1 after KOH activation has improved potential stability and reversibility compared to the all-solid-state calcium ion selective electrode prepared in comparative example 1 without activation.
Capacitive comparison test:
the all-solid-state calcium ion selective electrode prepared in the example 1 of the invention and the all-solid-state calcium ion selective electrode prepared in the comparative example 1 are respectively placed in 0.1mol/L CaCl2Cyclic voltammetric scanning is carried out in the solution, the experimental result is shown in fig. 5, PC is a cyclic voltammetric scanning chart of unactivated pine cone biochar, and APC1, APC3 and APC5 are KOH activation ratios of 1: 1. 1:3 and 1: 5 cyclic voltammogram.
As can be seen from fig. 5: compared with the comparative example 1, the all-solid-state calcium ion selective electrode prepared in the embodiment 1 of the invention has the advantages that the conductivity and the capacitance of the electrode are improved.
Comparative example 2:
this comparative example provides an all-solid-state calcium ion selective electrode, which is different from example 1 in that a single-walled carbon nanotube layer is not introduced in the comparative example, and the activation ratio is 1: 3.
And (4) water layer comparison test:
the all-solid-state calcium ion selective electrode prepared in example 1 of the present invention and the all-solid-state calcium ion selective electrode prepared in comparative example 2 were subjected to water layer testing, and the electrodes were immersed in 1mM CaCl2The solution was immersed for 2h, then 1mM NaCl solution for 2h, and finally 1mM CaCl2And continuously recording the potential response of the electrode after 8h of solution, and comparing the potential change before and after the electrode is immersed in the NaCl solution to verify the reversibility and water layer interference resistance of the electrode. The results of the experiment are shown in FIG. 6.
As can be seen from fig. 6: compared with the comparison ratio 2, the all-solid-state calcium ion selective electrode prepared in the embodiment 1 of the invention introduces the enhancement of the hydrophobicity of the electrode with the single-wall carbon nanotube layer, and improves the potential stability and the reversibility.
Example 2:
compared with the embodiment 1, the embodiment has the following differences: the calcium ionophore was replaced with the sodium ionophore N, N ', N "-triheptyl-N, N ', N" -trimethyl-4, 4 ', 4 "-propylidene tris (3-oxabutanamide), and the activation solution was replaced with 0.1mol/L sodium chloride solution, with the other parameters being the same as in example 1.
Example 3:
the embodiment provides an all-solid-state calcium ion selective electrode based on porous pine cone biochar and a preparation method thereof, and compared with embodiment 1, the difference of the embodiment is as follows: (1) the electrode substrate is a graphite electrode; (2) the electrophoretic electrodeposition voltage was 3.0V.
The above-mentioned embodiments are intended to illustrate the technical solutions and advantages of the present invention, and it should be understood that the above-mentioned embodiments are only specific embodiments of the present invention, and are not intended to limit the present invention, and any modifications, additions, equivalents, etc. made within the scope of the principles of the present invention should be included in the scope of the present invention.
Claims (10)
1. An all-solid-state ion selective electrode based on single-walled carbon nanotube composite porous pine cone biochar modification, the all-solid-state ion selective electrode comprising:
the conductive substrate, the porous pine cone biochar solid transduction layer modified on the outer surface of the conductive substrate, the single-walled carbon nanotube layer modified on the outer surface of the porous pine cone biochar solid transduction layer, and the ion selective membrane layer modified on the outer surface of the single-walled carbon nanotube layer;
the thickness of the porous pine cone biochar solid transfer layer is 0.05-0.1 mm; the thickness of the single-wall carbon nanotube layer is 0.05-0.1 mm; the thickness of the ion selective membrane layer is 0.05-0.15 mm.
2. The all-solid ion-selective electrode of claim 1, wherein the electrically conductive substrate comprises a graphite electrode, a glassy carbon electrode, a platinum electrode, or a gold electrode.
3. The all-solid ion-selective electrode of claim 1, wherein the raw material components for preparing the ion-selective membrane layer comprise:
a solute and a solvent with 4-8 times of the total mass of the solute;
the solute comprises the following components in percentage by mass as 100 percent: 0.5 to 4 percent of ion carrier, 25 to 35 percent of polymer, 60 to 70 percent of plasticizer and 0.5 to 1.5 percent of cation exchanger;
preferably, the solvent comprises tetrahydrofuran.
4. The all-solid ion-selective electrode according to claim 3, wherein the ionophore is a non-conductive high molecular polymer;
preferably, the ionophore comprises one or more of a calcium ionophore, a potassium ionophore, and a sodium ionophore;
preferably, the calcium ionophore comprises ETH 1001, 10, 19-bis [ (octadecylcarbamoyl) methoxyacetyl ] -1,4,7,13, 16-pentaoxa-10, 19-diazacycloheneicosane, (-) - (R, R) -N, N ' -bis- [11- (ethoxycarbonyl) undecyl ] -N, N ', 4, 5-tetramethyl-3, 6-dioxaoctane-diamide, diethyl N, N ' - [ (4R,5R) -4, 5-dimethyl-1, 8-dioxo-3, 6-dioxaoctylene ] bis (12-methylaminolaurate), N, N, N ', N ' -tetrakis [ cyclohexyl ] diglycolic acid diamide, N, N ' -bis (11-ethoxycarbonyl) undecyl ] -N, N ', 4, 5-tetramethyl-3, 6-dioxaoctane-diamide, N, N, N ' -bis (12-methylaminolaurate), N, N ', N ' -tetrakis [ cyclohexyl ] diglycolic acid diamide, N, N, N ' -bis (12-methyl-dioxaoctyl) amide, One or more of N, N' -tetracyclohexyl-3-oxaglutaramide and tert-butyl-calix [4] arene tetrakis [2- (diphenylphosphoryl) ethyl ether ];
preferably, the potassium ionophore includes one or more of valinomycin, 4-tert-butyl-2, 2,14, 14-tetraethyl-substituted-2 a,14a, dioxabridged calix [4] arene-tetra-tert-butyl tetraacetate, bis [ (benzo-15-crown-5) -4 ' -ylmethyl ] pimelate, and 2-dodecyl-2-methyl-1, 3-propanediylbis [ N- [5 ' -nitro (benzo-15-crown-5) -4 ' -yl ] carbamate ];
preferably, the sodium ionophore comprises N, N ', N "-triheptyl-N, N ', N" -trimethyl-4, 4 ', 4 "-propylidenediyl tris (3-oxabutanamide), N, N ' -dibenzyl-N, N ' -diphenyl-1, 2-phenylenedioxydiethylamide, N, N, N ', N ' -tetracyclohexyl-1, 2-phenylenedioxydiethylamide, 2,3:11, 12-bisdecahydronaphthalenyl-16-crown-5, 4-octadecanoic acid methyl-N, N, N ', N ' -tetracyclohexyl-1, 2-phenylenedioxyamide, bis [ (12-crown-4) methyl ] -2-dodecyl-2-propanedioic acid dimethyl ester, dimethyl ester, One or more of bis [ (12-crown-4) methyl ]2, 2-didodecylmalonate and 4-tert-butylcalix [4] arene-tetraacetic acid tetraethyl ester.
5. The all-solid ion-selective electrode of claim 3, wherein the polymer comprises one or more of polyvinyl chloride, an acrylic polymer, and a urethane rubber.
6. The all-solid ion-selective electrode of claim 3, wherein the plasticizer comprises one or more of o-nitrooctyl ether, an aromatic ether, a carboxylic acid ester, and a phosphate ester.
7. The all-solid ion-selective electrode of claim 3, wherein the cation exchanger comprises sodium tetrakis [3, 5-bis (trifluoromethyl) benzene ] borate and/or potassium tetrakis [3, 5-bis (trifluoromethyl) benzene ] borate.
8. The all-solid-state ion-selective electrode according to claim 1, wherein, in the porous pine cone biochar solid-state transition layer, the preparation method of the porous pine cone biochar comprises the following steps:
cleaning pine cone with ethanol, grinding into powder with a mortar, and heating and carbonizing the pine cone powder in argon atmosphere to obtain carbonized black pine cone charcoal powder;
uniformly mixing and stirring carbonized pine cone charcoal powder and an aqueous solution of an activating agent, and then transferring the mixture to a vacuum freeze dryer to remove water to obtain a solid mixture;
and heating the solid mixture in argon atmosphere for activation, centrifuging the cooled product to be neutral, and drying in vacuum to obtain the porous pine cone biochar.
9. The all-solid ion-selective electrode of claim 8, wherein the activator comprises one or more of potassium hydroxide, sodium hydroxide, zinc chloride, potassium carbonate, and sodium carbonate;
preferably, the mass percentage concentration of the aqueous solution of the activating agent is 10-80%;
preferably, the mass ratio of the carbonized pine cone charcoal powder to the activating agent is 1: (1-10);
preferably, the temperature for heating and carbonizing the pine cone powder in the argon atmosphere is 700-1000 ℃; the carbonization time is 120-240 min; the heating rate is 2-5 ℃/min;
preferably, the temperature for heating and activating the solid mixture in the argon atmosphere is 700-900 ℃; the activation time is 120-240 min; the heating rate is 2-5 ℃/min.
10. A method of making an all-solid ion-selective electrode according to any one of claims 1 to 9, comprising the steps of:
dispersing porous pine cone biochar in a mixed solution of water and ethanol and performing ultrasonic treatment to obtain a porous pine cone biochar dispersion solution; dripping the porous pine cone biochar on the surface of an electrode substrate, drying to form a film, and forming a porous pine cone biochar solid transfer layer on the surface of the electrode substrate;
depositing and decorating a single-walled carbon nanotube layer on the outer surface of the porous pine cone biochar solid-state transfer layer by adopting an electrophoretic electrodeposition method;
dripping solution of an ion selective film layer on the surface of the single-wall carbon nanotube layer in a vacuum drying box, and drying to form a film so as to form the ion selective film layer; finally preparing the all-solid-state ion selective electrode;
preferably, in the mixed solution of water and ethanol, the volume ratio of water to ethanol is (1-4): 1;
preferably, the method for depositing and modifying a single-walled carbon nanotube layer on the outer surface of the solid-state transduction layer of the porous pine cone biochar by adopting an electrophoretic electrodeposition method comprises the following steps:
dispersing single-walled carbon nanotubes in a mixed solution of concentrated nitric acid and concentrated sulfuric acid, performing ultrasonic treatment, washing to be neutral, dispersing the treated single-walled carbon nanotubes in water, performing ultrasonic treatment to obtain a uniformly dispersed solution, taking an electrode modified with a porous pinecone biochar solid transfer layer as an anode and a platinum wire as a cathode, and applying voltage to two ends of the electrode so as to modify the single-walled carbon nanotube layer on the electrode modified with the porous pinecone biochar solid transfer layer;
preferably, in the mixed solution of concentrated nitric acid and concentrated sulfuric acid, the volume ratio of concentrated nitric acid to concentrated sulfuric acid is 1: (1-5);
preferably, the voltage of the electrophoresis is 2-3V; the distance between the anode and the cathode is 1.5-2.5 mm.
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