A titanium-based composite electrode material and its preparation method and application

Abstract

The present invention relates to the technical field of oilfield produced water treatment, and discloses a titanium-based composite electrode material, a preparation method and application thereof, and a method for electrochemically disinfecting oilfield produced water. The method comprises: (1) subjecting a mixed solution A and a titanium substrate to a hydrothermal reaction under closed conditions to obtain a substance I; the mixed solution A contains a cobalt salt, a nickel salt, ammonium fluoride, and urea in a molar ratio of 1:0-1:2-8:4-15; the conditions of the hydrothermal reaction include a temperature of 100-160°C and a time of 2-10 hours; (2) subjecting the substance I to a first annealing treatment to obtain a substance II; (3) subjecting the substance II to an electrodeposition reaction and a second annealing treatment in sequence to obtain the titanium-based composite electrode material; the electrodeposition liquid in the electrodeposition reaction is an aqueous solution of a soluble antimony salt or an ethylene glycol solution of a soluble antimony salt; and the titanium-based composite electrode material prepared by the present invention is used to electrochemically disinfect oilfield produced water, achieving good results and low cost.

Description

Technical Field

[0001] The present invention relates to the field of oilfield produced water treatment, and in particular to a titanium-based composite electrode material, a preparation method and application thereof, and a method for electrochemically disinfecting oilfield produced water. Background Art

[0002] With the widespread application of fracturing technology in unconventional oil and gas field development, the resulting large amounts of produced water require various treatment methods, including compounding, reservoir injection, and discharge to meet standards. Reservoir injection is a relatively economical and environmentally friendly approach, with lower treatment costs than compounding and discharge to meet standards, and it facilitates the recycling of oilfield water resources.

[0003] Key indicators of concern for reservoir reinjection include oil content, suspended solids, and bacterial content. High concentrations of petroleum, suspended solids, and chemical oxygen demand (COD) can adversely affect the water injection system. The proliferation of bacteria (such as sulfate-reducing bacteria (SRB), iron bacteria (IB), and saprophytic bacteria (TGB)) and the production of FeS, a corrosion product, can not only cause foul odors in the water but also lead to serious consequences such as pipeline blockage, equipment corrosion, and decreased reservoir permeability, resulting in significant economic losses for the oilfield. Therefore, it is necessary to sterilize oilfield produced water to effectively address the corrosion problem of reservoir reinjection water and achieve efficient recycling of oilfield water resources.

[0004] There are many sterilization methods used for oilfield reinjection wastewater, which can be broadly categorized into three types. The first is physical methods, such as ultraviolet (UV) sterilization. However, UV only temporarily shocks bacteria like SRB. Furthermore, oils, grease, and polymers in oilfield wastewater interfere with light absorption, resulting in poor UV sterilization effectiveness. The second is chemical methods (such as the addition of formaldehyde, benzene, and quaternary ammonium salts for sterilization). However, these methods are subject to operational challenges, such as pipeline corrosion, increased bacterial resistance, high labor and dosing costs, and poor sterilization effectiveness. The third is electrochemical methods, such as electrolytic salt electrochemical methods. Electrochemical methods are effective, environmentally friendly, and versatile alternative water disinfection methods, attracting increasing attention in various fields, including social life and industrial production.

[0005] Electrochemical disinfection mainly involves two main mechanisms: one is the direct oxidation of the electrode surface, which causes instantaneous inactivation of microbial cells and disinfection; the other is the in situ generation of reactive oxygen species (such as H2O2, O3, etc.) or reactive chlorine (such as Cl2, HClO, etc.) on the electrode surface to promote disinfection.

[0006] For oilfield produced water with high chlorine content, the rapid generation of active chlorine in situ by electrochemical means can reduce the dosage of chemical agents and destroy the enzyme system in bacterial cells to achieve the purpose of sterilization. At the same time, the active chlorine generated by electrochemical means can also oxidize the reduced Fe 2+ 、S 2-This technology removes organic matter and reduces water corrosion on pipelines and equipment, ensuring that treated oilfield produced water meets the standards for reservoir reinjection water. Furthermore, electrochemical disinfection can be combined with photovoltaic and wind power generation technologies to disinfect oilfield produced water locally, ensuring it meets the requirements for oilfield reinjection water. This provides a promising approach for energy conservation, consumption reduction, and sustainable development in oilfields.

[0007] Currently, the most widely studied electrochemical disinfection method is dimensionally stable electrodes (DSAs) based on precious metal oxides such as ruthenium and iridium. These precious metal oxides are not only expensive but also prone to dissolution or shedding under extreme conditions, leading to electrode passivation and severely impacting electrode activity and long-term stability. Furthermore, the oxygen evolution reaction (OER) inevitably occurs during the generation of active chlorine. As electrolysis time increases, the chlorine evolution overpotential gradually increases, competing with the OER, further reducing the selectivity of the chlorine evolution reaction and increasing the energy consumption and cost of electrochemical disinfection.

[0008] CN117209017A discloses the preparation and application of an iron-doped suboxidized state electrode. The chlorine evolution reaction potential of the electrode is greater than 1.8V, which easily competes with the oxygen evolution reaction, thereby deteriorating the electrode's chlorine evolution selectivity and increasing the cost of electrochemical disinfection of the electrode. Summary of the Invention

[0009] The purpose of the present invention is to overcome the problems of poor effect of chemical disinfection of oilfield produced water, high cost and poor selectivity of electrochemical disinfection.

[0010] In order to achieve the above object, the first aspect of the present invention provides a method for preparing a titanium-based composite electrode material, the method comprising:

[0011] (1) Under closed conditions, a mixed solution A and a titanium substrate are subjected to a hydrothermal reaction to obtain a substance I; the mixed solution A contains a cobalt salt, a nickel salt, ammonium fluoride, and urea in a molar ratio of 1:0-1:2-8:4-15; the hydrothermal reaction conditions include: a temperature of 100-160°C and a time of 2-10 hours;

[0012] (2) subjecting the substance I to a first annealing treatment to obtain a substance II; the conditions of the first annealing treatment include: an annealing temperature of 300-600°C and an annealing time of 2-4 hours;

[0013] (3) subjecting the substance II to an electrodeposition reaction and a second annealing treatment in sequence to obtain the titanium-based composite electrode material;

[0014] The electrodeposition solution in the electrodeposition reaction is an aqueous solution of a soluble antimony salt or an ethylene glycol solution of a soluble antimony salt; and the concentration of the antimony element in the electrodeposition solution is 1-10 mmoL / L; the conditions of the electrodeposition reaction include: a current density of 5-30 mA / cm 2 , the electrodeposition time is 60-120 min.

[0015] The second aspect of the present invention provides a titanium-based composite electrode material prepared by the method described in the first aspect.

[0016] The third aspect of the present invention provides the use of the titanium-based composite electrode material described in the second aspect in the electrochemical disinfection of oilfield produced water.

[0017] A fourth aspect of the present invention provides a method for electrochemically disinfecting oilfield produced water, the method comprising: sequentially subjecting the oilfield produced water to flocculation pretreatment, filtration treatment, and electrolysis treatment;

[0018] The electrolytic treatment conditions include: using the titanium-based composite electrode material as the anode, and the current density is 10-20 mA / cm 2 , time 5-30min, stirring speed 400-800 rpm; the titanium-based composite electrode material is the titanium-based composite electrode material described in the second aspect.

[0019] The present invention has at least the following advantages:

[0020] (1) The titanium-based composite electrode material of the present invention has the advantages of high stability, high chlorine evolution selectivity and low cost;

[0021] (2) The titanium-based composite electrode material of the present invention is highly efficient in chemically disinfecting oilfield produced water. It can fully utilize the chloride ions in the oilfield produced water and generate active chlorine with bactericidal effects in situ through electrochemical disinfection without adding additional chemical disinfectants, thereby reducing the corrosion of equipment and pipelines caused by bacteria in the oilfield produced water. At the same time, it can effectively reduce the disinfection treatment cost of oilfield produced water.

[0022] (3) When the titanium-based composite electrode material of the present invention is used for chemical disinfection of oilfield produced water, it can produce electroactive substances that can effectively oxidize reducing substances in the water, such as ferrous sulfide, thereby reducing the impact of reinjection water on formation permeability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 These are scanning electron microscope images of the materials prepared in this scheme, where (a) represents a scanning electron microscope image of the pretreated titanium foam, and (b), (c), and (d) represent scanning electron microscope images of the titanium-based composite electrode material prepared in Example 1 at different magnifications, respectively.

[0024] Figure 2 The electrochemical linear sweep voltammetry curves of the titanium-based composite electrode materials prepared in Examples 1 to 4 are shown.

[0025] Figure 3 These are the renderings of oilfield produced water at different treatment stages of electrochemical disinfection, where (a) represents the rendering of the raw oilfield produced water; (b) represents the rendering of the oilfield produced water after flocculation pretreatment; (c) represents the rendering of the oilfield produced water after filtration treatment; and (d) represents the rendering of the oilfield produced water after electrolysis treatment.

[0026] Figure 4 The titanium-based composite electrode material prepared in Example 1 and the commercially available Ti-plate / RuO2-IrO2 electrode in Comparative Example 4 are compared to show the changes of some components over time during the electrolysis treatment of oilfield produced water obtained after flocculation pretreatment and filtration treatment: (a) shows the change of SRB content in oilfield produced water over the time of electrolysis treatment; (b) shows the change of IB content over the time of electrolysis treatment; (c) shows the change of COD concentration over the time of electrolysis treatment; (d) shows the change of S 2- Changes in concentration with electrolysis treatment time; (e) Fe 2+ (f) Changes in suspended solids concentration with time of electrolysis treatment. DETAILED DESCRIPTION

[0027] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0028] As mentioned above, the first aspect of the present invention provides a method for preparing a titanium-based composite electrode material, the method comprising:

[0029] (1) Under closed conditions, a mixed solution A and a titanium substrate are subjected to a hydrothermal reaction to obtain a substance I; the mixed solution A contains a cobalt salt, a nickel salt, ammonium fluoride, and urea in a molar ratio of 1:0-1:2-8:4-15; the hydrothermal reaction conditions include: a temperature of 100-160°C and a time of 2-10 hours;

[0030] (2) subjecting the substance I to a first annealing treatment to obtain a substance II; the conditions of the first annealing treatment include: an annealing temperature of 300-600°C and an annealing time of 2-4 hours;

[0031] (3) subjecting the substance II to an electrodeposition reaction and a second annealing treatment in sequence to obtain the titanium-based composite electrode material;

[0032] The electrodeposition solution in the electrodeposition reaction is an aqueous solution of a soluble antimony salt or an ethylene glycol solution of a soluble antimony salt; and the concentration of the antimony element in the electrodeposition solution is 1-10 mmoL / L; the conditions of the electrodeposition reaction include: a current density of 5-30 mA / cm 2 , the electrodeposition time is 60-120 min.

[0033] The titanium substrate in the present invention serves as a carrier in the titanium-based composite material. Therefore, the amount of the titanium substrate used is such that the remaining components in the prepared titanium-based composite material can be dispersed on the titanium substrate.

[0034] Preferably, in step (1), the conditions of the hydrothermal reaction include: a temperature of 120-140°C and a time of 4-6 hours. The inventors of the present invention have found that, under this preferred condition, the titanium-based composite electrode material prepared by the method of the present invention has excellent stability and chlorine evolution selectivity, and is more effective in electrochemical disinfection of oilfield produced water.

[0035] Preferably, in step (2), the heating rate of the first annealing treatment is 1-10°C / min.

[0036] According to a particularly preferred embodiment, the conditions for the first annealing treatment include: an annealing temperature of 300-400°C, an annealing time of 2-3 hours, and a heating rate of 4-8°C / min. The inventors of the present invention have discovered that, under this preferred embodiment, the titanium-based composite electrode material prepared by the method of the present invention exhibits excellent stability and chlorine evolution selectivity, and is more effective for electrochemical disinfection of oilfield produced water.

[0037] Preferably, in step (3), the conditions of the electrodeposition reaction include: a current density of 10-20 mA / cm 2 , the electrodeposition time is 60-100 min.

[0038] Preferably, in step (3), the conditions of the second annealing treatment include: annealing temperature of 300-600 °C, and annealing time of 2-4 h.

[0039] Further preferably, the heating rate of the second annealing treatment is 1-10° C. / min.

[0040] According to a particularly preferred embodiment, the conditions for the second annealing treatment include: an annealing temperature of 400-500°C, an annealing time of 2-3 hours, and a heating rate of 1-5°C / min. The inventors of the present invention have discovered that, under this preferred embodiment, the titanium-based composite electrode material prepared by the method of the present invention has excellent stability and chlorine evolution selectivity, and is more effective for electrochemical disinfection of oilfield produced water.

[0041] Preferably, in step (1), the cobalt salt is selected from any one of cobalt nitrate and its hydrate, cobalt chloride and its hydrate, cobalt sulfate and its hydrate, cobalt oxalate and its hydrate, and cobalt acetate and its hydrate.

[0042] Preferably, in step (1), the nickel salt is selected from any one of nickel chloride and its hydrate, nickel nitrate and its hydrate, and nickel sulfate and its hydrate.

[0043] Preferably, in step (1), the titanium substrate is selected from any one of titanium foam, titanium mesh and titanium felt.

[0044] Preferably, in step (3), the electrodeposition solution is an aqueous solution of SbCl3 or an ethylene glycol solution of SbCl3.

[0045] According to a particularly preferred embodiment, in step (1), the cobalt salt is cobalt nitrate hexahydrate, the nickel salt is nickel chloride hexahydrate, and the titanium substrate is foamed titanium; in step (3), the electrodeposition solution is an ethylene glycol solution of SbCl3.

[0046] It should be noted that the electrodeposition reaction method of the present invention includes: performing an electrodeposition reaction using the substance II as a cathode under specific conditions of current density, electrodeposition time and electrodeposition solution.

[0047] According to a preferred embodiment, the electrodeposition reaction method comprises: 2 The electrodeposition reaction is carried out under constant current using Substance II as the cathode and graphite as the anode, with an electrodeposition time of 60-100 minutes and a 1-10 mmol / L / L SbCl3 ethylene glycol solution as the electrodeposition liquid. The inventors have discovered that, under this preferred embodiment, the titanium-based composite electrode material prepared by the method of the present invention exhibits excellent stability and chlorine evolution selectivity, and is more effective for electrochemical disinfection of oilfield produced water.

[0048] Preferably, the method further comprises pre-treating the titanium substrate before performing step (1).

[0049] Further preferably, the pretreatment method includes: performing a first heat treatment on the titanium substrate in an alkaline solution and then washing it with water until it is neutral to obtain a titanium substrate-1; performing a second heat treatment on the titanium substrate-1 in an acidic solution and then washing it with water until it is neutral to obtain a titanium substrate-2; performing a third heat treatment on the titanium substrate-2 in a second acidic solution and then washing it with water until it is neutral.

[0050] According to a particularly preferred embodiment, the pretreatment method comprises: heating the titanium substrate in a mixed solution containing 10-80 g / L of sodium hydroxide and 10-80 g / L of sodium carbonate at 85-100°C in a first oil bath for 30-60 minutes, followed by rinsing with deionized water until neutral, to obtain titanium substrate-1; heating the titanium substrate-1 in a 10-30 vol% hydrochloric acid solution at 85-100°C in a second oil bath for 30-90 minutes, followed by rinsing with deionized water until neutral, to obtain titanium substrate-2; and heating the titanium substrate-2 in a 5-30 wt% oxalic acid solution at 85-100°C in a third oil bath for 60-120 minutes, followed by rinsing with deionized water until neutral. The inventors of the present invention have found that, in this preferred embodiment, the titanium-based composite electrode material prepared by the method of the present invention has excellent stability and chlorine evolution selectivity, and is more effective for electrochemical disinfection of oilfield produced water.

[0051] Further preferably, the first oil bath heating time is 30-40 min; the second oil bath heating time is 30-60 min; and the third oil bath heating time is 60-90 min.

[0052] Preferably, the method further comprises stirring the mixed solution A before performing step (1).

[0053] There is no particular limitation on the stirring conditions in the present invention, as long as the mixed solution A after stirring is a pink clear solution. Those skilled in the art can select the stirring conditions as needed, which should not be construed as limiting the present invention.

[0054] As mentioned above, the second aspect of the present invention provides a titanium-based composite electrode material prepared by the method described in the first aspect.

[0055] As mentioned above, the third aspect of the present invention provides the use of the titanium-based composite electrode material described in the second aspect in the electrochemical disinfection of oilfield produced water.

[0056] As mentioned above, the fourth aspect of the present invention provides a method for electrochemical disinfection of oilfield produced water, the method comprising: sequentially subjecting the oilfield produced water to flocculation pretreatment, filtration treatment, and electrolysis treatment;

[0057] The electrolytic treatment conditions include: using the titanium-based composite electrode material as the anode, and the current density is 10-20 mA / cm -2 , time 5-30min, stirring speed 400-800 rpm; the titanium-based composite electrode material is the titanium-based composite electrode material described in the second aspect.

[0058] In the present invention, the power source for the electrolysis treatment is a direct current power source or a pulse power source.

[0059] Further preferably, the distance between the cathode plate and the anode plate of the electrolysis treatment is 1-3 cm.

[0060] Preferably, the flocculation pretreatment adopts the method of electric flocculation, and the conditions of the electric flocculation include: the anode plate is an aluminum electrode or an iron electrode, the distance between the cathode plate and the anode plate is 1-3 cm, and the current density is 1-6 mA / cm 2 , time 10-20min, stirring speed 300-1000 rpm.

[0061] In the present invention, the power source for the electric flocculation is a direct current power source or a pulse power source.

[0062] There is no particular limitation on the filtration treatment in the present invention. Those skilled in the art can select the filtration treatment by conventional methods, which should not be construed as a limitation on the present invention.

[0063] SRB in the present invention means sulfate-reducing bacteria.

[0064] IB in the present invention represents iron bacteria.

[0065] TGB in the present invention means saprophytic bacteria.

[0066] COD in the present invention means chemical oxygen demand.

[0067] TDS in the present invention means total dissolved solids.

[0068] LSV in the present invention represents linear sweep voltammetry

[0069] In the following examples, unless otherwise specified, the raw materials are all common commercially available products.

[0070] Titanium foam: 4 cm × 4 cm × 1.5 cm, purchased from Taizhou Xuance Metal Products Co., Ltd.

[0071] Ti-plate / RuO2-IrO2: ruthenium-iridium-titanium electrode, purchased from Xi'an Xinhengtai New Material Technology Co., Ltd.

[0072] Example 1

[0073] (1) Pretreatment of titanium foam: The titanium foam was heated in a first oil bath at 85°C for 30 min in a mixed solution containing 30 g / L sodium hydroxide and 30 g / L sodium carbonate, and then rinsed with deionized water until neutral, to obtain titanium substrate-1; the titanium substrate-1 was heated in a second oil bath at 98°C for 60 min in a 30 vol% hydrochloric acid solution, and then rinsed with deionized water until neutral, to obtain titanium substrate-2; the titanium substrate-2 was heated in a third oil bath at 95°C for 60 min in a 15 wt% oxalic acid solution, and then rinsed with deionized water until neutral;

[0074] (2) A mixed solution A containing cobalt nitrate hexahydrate, nickel chloride hexahydrate, ammonium fluoride and urea in a molar ratio of 1:0.1:3.6:5.6 is stirred, wherein the cobalt nitrate hexahydrate is 6 mol, so that the mixed solution A becomes a pink clear solution; under closed conditions, the stirred mixed solution A and the pretreated titanium foam are hydrothermally reacted at 140°C for 6 hours to obtain substance I;

[0075] (3) After rinsing the material I with deionized water, the material was subjected to a first annealing treatment at 300°C for 2 h with a heating rate of 5°C / min to obtain the material II;

[0076] (4) subjecting the substance II to an electrodeposition reaction and a second annealing treatment in sequence to obtain the titanium-based composite electrode material;

[0077] The electrodeposition reaction includes: using material II as cathode and graphite plate as anode at a current density of 20 mA / cm 2 Under the condition of constant current electrodeposition in 10 mmol / L SbCl3 ethylene glycol solution for 60 min;

[0078] The conditions of the second annealing treatment include: annealing temperature of 400° C., time of 2 h, and heating rate of 5° C. / min.

[0079] Example 2

[0080] This embodiment adopts a similar process to that of Example 1, except that, in step (2), the mixed solution A containing cobalt nitrate hexahydrate, nickel chloride hexahydrate, ammonium fluoride and urea in a molar ratio of 1:0.1:3.6:5.6 is adjusted to a mixed solution A containing cobalt nitrate hexahydrate, nickel chloride hexahydrate, ammonium fluoride and urea in a molar ratio of 1:0:3.2:5, wherein the cobalt nitrate hexahydrate is 6 mol, and the rest is the same as in Example 1, to obtain the titanium-based composite electrode material.

[0081] Example 3

[0082] This embodiment adopts a similar process to that of Example 1, except that, in step (2), the mixed solution A containing cobalt nitrate hexahydrate, nickel chloride hexahydrate, ammonium fluoride and urea in a molar ratio of 1:0.1:3.6:5.6 is adjusted to a mixed solution A containing cobalt nitrate hexahydrate, nickel chloride hexahydrate, ammonium fluoride and urea in a molar ratio of 1:0.32:4.2:6.6, wherein the cobalt nitrate hexahydrate is 6 mol, and the rest is the same as in Example 1, to obtain the titanium-based composite electrode material.

[0083] Example 4

[0084] This embodiment adopts a similar process to that of Example 1, except that, in step (2), the mixed solution A containing cobalt nitrate hexahydrate, nickel chloride hexahydrate, ammonium fluoride and urea in a molar ratio of 1:0.1:3.6:5.6 is adjusted to a mixed solution A containing cobalt nitrate hexahydrate, nickel chloride hexahydrate, ammonium fluoride and urea in a molar ratio of 1:0.52:4.8:7.6, wherein the cobalt nitrate hexahydrate is 6 mol, and the rest is the same as in Example 1, to obtain the titanium-based composite electrode material.

[0085] Comparative Example 1

[0086] This comparative example adopts a similar process to Example 1, except that in step (2), the conditions of the hydrothermal reaction are adjusted to: temperature of 180° C., annealing time of 6 h, and the rest are the same as Example 1 to prepare the titanium-based composite electrode material.

[0087] Comparative Example 2

[0088] This comparative example adopts a process similar to that of Example 1, except that, in step (2), the mixed solution A containing cobalt nitrate hexahydrate, nickel chloride hexahydrate, ammonium fluoride and urea in a molar ratio of 1:0.1:3.6:5.6 is adjusted to a mixed solution A containing cobalt nitrate hexahydrate, nickel chloride hexahydrate, ammonium fluoride and urea in a molar ratio of 1:1.2:3.6:5.6, wherein the cobalt nitrate hexahydrate is 6 mol, and the rest is the same as in Example 1, to obtain the titanium-based composite electrode material.

[0089] Comparative Example 3

[0090] This comparative example adopts a similar process to Example 1, except that in step (4), the 10 mmol / L SbCl3 ethylene glycol solution electrodeposition liquid is replaced with a 15 mmol / L SbCl3 ethylene glycol solution. The rest is the same as Example 1 to prepare the titanium-based composite electrode material.

[0091] Comparative Example 4

[0092] The titanium-based composite electrode material is commercially available Ti-plate / RuO2-IrO2.

[0093] Comparative Example 5

[0094] This comparative example uses a similar process to Example 1, except that in step (3), the conditions for the first annealing treatment include: a temperature of 700°C, an annealing time of 2h, and a heating rate of 5°C / min to prepare the titanium-based composite electrode material.

[0095] Test Example 1

[0096] Chlorine evolution reaction potential and oxygen evolution reaction potential of the material; the present invention exemplarily selects Example 1, Example 2, Example 3, Example 4 and Comparative Example 4 for testing:

[0097] S1: Prepare 4 mol / L sodium chloride (pH=2) solution and 0.5 mol / L Na2SO4 solution respectively.

[0098] S2: The titanium-based composite electrode materials prepared in Examples 1 to 4 and the commercially available Ti-plate / RuO2-IrO2 were used as working electrodes, respectively. The working electrode area was 1 cm 2 ; A platinum mesh was used as the counter electrode with an area of 4 cm 2 The LSV potential of chlorine evolution reaction was measured in 4 mol / L sodium chloride (pH=2) solution at room temperature (26°C) using Ag / AgCl electrode as reference electrode. The scan rate was 50 mV / s and the potential range was 0~2 V.

[0099] Step S3: The titanium-based composite electrode materials prepared in Examples 1 to 4 and the commercially available Ti-plate / RuO2-IrO2 electrodes were used as working electrodes, respectively. The working electrode area was 1 cm 2 ; Platinum mesh was used as the counter electrode, and the counter electrode area was 4 cm 2 The LSV oxygen evolution reaction potential was measured in 0.5 mol / L Na2SO4 solution at room temperature (26°C) using an Ag / AgCl electrode as the reference electrode. The scan rate was 50 mV / s and the potential range was 0-2.5 V.

[0100] According to the Nernst equation (E RHE =E Ag / AgC1 +0.0591×pH+0.198) to convert the measured electrode potential relative to the Ag / AgCl electrode to the electrode potential relative to the reversible hydrogen electrode (RHE), and all electrochemical experiments were subjected to 90% IR compensation. Among them, the comparison results of the chlorine evolution reaction potential and oxygen evolution reaction potential of the two electrodes of Example 1 and Comparative Example 4 are shown in Table 1. The electrochemical linear sweep voltammetry curves of Examples 1 to 4 are shown in Figure 2 shown.

[0101] Table 1

[0102]

[0103] As can be seen from Table 1, the titanium-based composite electrode material prepared in the present invention has a chlorine evolution reaction potential that is 0.04 V higher than that of the commercially available Ti-plate / RuO2-IrO2 electrode, but its oxygen evolution reaction potential is 0.13 V higher than that of the commercially available Ti-plate / RuO2-IrO2 electrode. A comprehensive comparison shows that the difference between its chlorine evolution reaction potential and oxygen evolution reaction potential is 0.09 V higher than that of the commercially available Ti-plate / RuO2-IrO2 electrode, which significantly improves the selectivity of the chlorine evolution reaction.

[0104] Overpotential is also a very critical parameter in the application of electrocatalytic materials, which directly affects the energy consumption of electrocatalytic materials. The titanium-based composite electrode material prepared by the present invention is compared with the commercially available Ti-plate / RuO2-IrO2 electrode at a current density of 10 mA / cm 2 The potentials of the chlorine evolution reaction are 1.436V and 1.454V respectively. It can be seen that under the same current density, the titanium-based composite electrode material prepared by the present invention has a smaller electrode overpotential and a corresponding lower application energy consumption.

[0105] Test Example 2

[0106] The titanium-based composite electrode materials prepared in Examples 1 to 4, the titanium-based composite materials prepared in Comparative Examples 1 to 3 and 5, and the commercially available Ti-plate / RuO2-IrO2 electrode of Comparative Example 4 were used to disinfect oilfield produced water to meet the requirements of reinjection water. The specific steps are as follows:

[0107] M1: 1000 mL of oilfield produced water (the water quality analysis results are shown in Table 2) was taken and placed in an electrochemical reactor. Two aluminum plates with dimensions of 100 mm × 100 mm × 2 mm were used as anode and cathode, respectively. The distance between the plates was 2 cm. The stirring rate was 500 rpm and the current was 5 mA / cm 2 The mixture was pretreated with electro-flocculation at a current density of 20 min and then filtered to remove suspended solids and grease.

[0108] M2: 250 mL of filtered oilfield produced water was taken, and the pH of the solution was not changed. The titanium-based composite electrode materials prepared in Examples 1 to 4, the titanium-based composite materials prepared in Comparative Examples 1 to 3 and 5, and the commercially available Ti-plate / RuO2-IrO2 electrode of Comparative Example 4 were used as anodes, and a stainless steel electrode was used as cathode. A DC power supply was used with a current density of 14 mA / cm 2, the plate spacing was 2 cm, the stirring rate was 400 rpm, and the electrolysis treatment time was 15 min, so that the oilfield produced water met the reinjection standard. The results are shown in Table 2 (test results of Example 1), Table 3 (test results of Example 2), Table 4 (test results of Example 3), Table 5 (test results of Example 4), Table 6 (test results of Comparative Example 1), Table 7 (test results of Comparative Example 2), Table 8 (test results of Comparative Example 3), Table 9 (test results of Comparative Example 4), and Table 10 (test results of Comparative Example 5).

[0109] Table 2

[0110]

[0111] Table 3

[0112]

[0113] Table 4

[0114]

[0115] Table 5

[0116]

[0117] Table 6

[0118]

[0119] Table 7

[0120]

[0121] Table 8

[0122]

[0123] Table 9

[0124]

[0125] Table 10

[0126]

[0127] Figure 2 The electrochemical linear sweep voltammetry curves of the titanium-based composite electrode materials prepared in Examples 1 to 4 in a 4 mol / L sodium chloride (pH=2) solution are shown in FIG. Figure 2 It can be found that different titanium-based composite materials obtained by changing the dosage ratio of each component in the mixed solution A during the preparation process have different potentials for the chlorine evolution reaction at corresponding current densities. Figure 2 When the current density is 50 mA / cm 2When the current density is 100 mA / cm 2 When the chlorine evolution potentials of the titanium-based composite electrode materials prepared in Examples 1 to 4 were 1.58 V, 1.67 V, 1.62 V, and 1.75 V, respectively, it was found that the chlorine evolution potential of the electrode can be optimized by changing the dosage ratio of each component in the mixed solution A.

[0128] Figure 3 The figures show the effects of electrochemical disinfection of oilfield produced water at different treatment stages using the titanium-based composite electrode material prepared in Example 1: (a) represents the raw oilfield produced water; (b) represents the oilfield produced water after electrocoagulation pretreatment; (c) represents the oilfield produced water obtained after filtration treatment; and (d) represents the oilfield produced water after electrolysis treatment.

[0129] Depend on Figure 3 It can be seen that the electro-flocculation pretreatment and filtration treatment are mainly used to remove suspended matter and grease in oilfield produced water, and the electrolysis treatment can further eliminate bacterial substances and some difficult-to-remove reducing substances in oilfield produced water.

[0130] Figure 4 Comparison of the electrolytic treatment effects of the titanium-based composite electrode material prepared in Example 1 and the commercially available Ti-plate / RuO2-IrO2 electrode on oilfield produced water after electrocoagulation pretreatment and filtration treatment: (a) shows the change of SRB content over time; (b) shows the change of IB content over time; (c) shows the change of COD concentration over time; (d) shows S 2- Concentration changes over time; (e) represents Fe 2+ (f) represents the change of suspended matter concentration over time.

[0131] Depend on Figure 4 It can be seen that as the electrolysis treatment time increases, the sulfate-reducing bacteria (SRB), iron bacteria (IB), COD, S 2- 、Fe 2+ The contents of SRB, IB, and S 2- and Fe 2+ After electrolysis for 15 min using the commercially available Ti-plate / RuO2-IrO2 electrode and the titanium-based composite electrode material prepared in Example 1, the SRB contents were 6 and 0.6, respectively; the IB contents were 25 and 0, respectively; the COD concentrations were 318 and 244 mg / L, respectively; and the S 2-The concentrations were 0.3 mg / L and 0 mg / L respectively; Fe 2+ The concentrations were 0.02 mg / L and 0 mg / L, respectively; the suspended matter concentrations were 3 mg / L and 0 mg / L, respectively. It can be seen that the titanium-based composite electrode material prepared in Example 1 has a more significant electrochemical sterilization effect and higher degradation efficiency. After electrochemical sterilization, all indicators of the oilfield produced water meet the reinjection requirements of "SY-T 5329-2012 Recommended Indicators and Analysis Methods for Water Quality in Clastic Reservoirs for Water Injection."

[0132] It can be seen from Table 2, Table 3, Table 4, Table 5, Table 6, Table 7, Table 8, Table 9 and Table 10 that the titanium-based composite electrode material prepared by the present invention can be used as an electrochemical disinfection anode to effectively remove sulfate-reducing bacteria (SRB) and iron bacteria (IB) in oilfield produced water, and at the same time oxidize the reducing substances (such as S 2- and Fe 2+ ), while also further removing COD, oil content, and suspended solids, reducing corrosion to pipelines and equipment and minimizing the impact on reservoir permeability. After treatment with electrochemical disinfection, oilfield produced water meets the requirements for oilfield reinjection water, facilitating the effective recycling of oilfield water resources and contributing to the sustainable development of the oilfield.

[0133] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing a titanium-based composite electrode material, characterized in that: The method includes: (1) Under closed conditions, a mixed solution A and a titanium substrate are subjected to a hydrothermal reaction to obtain a substance I; the mixed solution A contains a cobalt salt, a nickel salt, ammonium fluoride, and urea in a molar ratio of 1:0-1:2-8:4-15; the hydrothermal reaction conditions include: a temperature of 100-160°C and a time of 2-10 hours; (2) subjecting the substance I to a first annealing treatment to obtain a substance II; the conditions of the first annealing treatment include: an annealing temperature of 300-600°C and an annealing time of 2-4 hours; (3) subjecting the substance II to an electrodeposition reaction and a second annealing treatment in sequence to obtain the titanium-based composite electrode material; the conditions of the second annealing treatment include: an annealing temperature of 300-600°C, an annealing time of 2-4 h; and a heating rate of the second annealing treatment of 1-10°C / min; The electrodeposition solution in the electrodeposition reaction is an aqueous solution of a soluble antimony salt or an ethylene glycol solution of a soluble antimony salt; and the concentration of the antimony element in the electrodeposition solution is 1-10 mmoL / L; the conditions of the electrodeposition reaction include: a current density of 5-30 mA / cm 2 , the electrodeposition time is 60-120 min.

2. The method according to claim 1, characterized in that In step (1), the conditions of the hydrothermal reaction include: temperature of 120-140° C. and time of 4-6 h.

3. The method according to claim 1 or 2, characterized in that In step (2), the heating rate of the first annealing treatment is 1-10 °C / min.

4. The method according to claim 1, wherein In step (3), the conditions of the electrodeposition reaction include: a current density of 10-20 mA / cm 2 , the electrodeposition time is 60-80 min.

5. The method according to claim 1, wherein In step (1), the cobalt salt is selected from any one of cobalt nitrate and its hydrate, cobalt chloride and its hydrate, cobalt sulfate and its hydrate, cobalt oxalate and its hydrate, and cobalt acetate and its hydrate; And / or, in step (1), the nickel salt is selected from any one of nickel chloride and its hydrate, nickel nitrate and its hydrate, and nickel sulfate and its hydrate; And / or, in step (1), the titanium substrate is selected from any one of titanium foam, titanium mesh and titanium felt; And / or, in step (3), the electrodeposition solution is an ethylene glycol solution of SbCl3.

6. The method according to claim 1, characterized in that The method further comprises pre-treating the titanium substrate before performing step (1); And / or, the pretreatment method includes: performing a first heat treatment on the titanium substrate in an alkaline solution and then washing it with water until it is neutral to obtain a titanium substrate-1; performing a second heat treatment on the titanium substrate-1 in a first acidic solution and then washing it with water until it is neutral to obtain a titanium substrate-2; performing a third heat treatment on the titanium substrate-2 in a second acidic solution and then washing it with water until it is neutral.

7. The titanium-based composite electrode material prepared by the method according to claim 1.

8. Use of the titanium-based composite electrode material according to claim 7 in electrochemical disinfection of oilfield produced water.

9. A method for electrochemical disinfection of oilfield produced water, characterized in that: The method comprises: sequentially subjecting oilfield produced water to flocculation pretreatment, filtration treatment and electrolysis treatment; The electrolytic treatment conditions include: using the titanium-based composite electrode material as the anode, and the current density is 10-20 mA / cm 2 , time 5-30min, stirring speed 400-800 rpm; the titanium-based composite electrode material is the titanium-based composite electrode material according to claim 7.

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