Method for catalytically degrading pesticide residues by nano-enzyme

Abstract

The invention belongs to the technical field of water treatment, and particularly relates to a method for catalytically degrading pesticide residues by nano-enzyme. The invention discloses a method for catalytically degrading pesticide residues by nano-enzyme. Transition metal oxide and a carbon-based composite carrier are adopted to form a nano-enzyme material, the specific surface area is 200-500 m < 2 > / g, and metal elements are at least two of iron, copper and cobalt. The method comprises the following steps: adding 0.1-1g / L of nano enzyme and 0.1-5mmol / L of H2O2 into a water body, and degrading organic phosphorus, pyrethroid or carbamate pesticides under the conditions that the pH is 4-10 and the temperature is 20-50 DEG C. The material activity and stability are synergistically improved. And the transition metal oxide and the carbon-based carrier form a chemical bonding interface, so that the dispersity of the active metal is improved to 85% or above. The equipment comprises a permanent magnet array recovery nano enzyme and a PID temperature control unit. The degradation rate in 60 minutes exceeds 90%, the reuse activity in 10 times is kept 92%, no iron sludge is discharged, and the cost of per ton of water is reduced to 0.23 yuan.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, specifically relating to a method for the catalytic degradation of pesticide residues using nanozymes. Background Technology

[0002] Pesticide residue pollution has become a core threat to global water safety. Due to their chemical stability, organophosphates, pyrethroids, and carbamates have half-lives in natural water bodies ranging from tens to hundreds of days. These compounds enter the water cycle through agricultural runoff and industrial wastewater, posing significant risks to aquatic life and human health even at concentrations in the μg / L range. The World Health Organization's Guidelines for Drinking-water Quality clearly limit the concentration of a single pesticide residue to no more than 0.1 μg / L, but actual monitoring shows that the concentrations of organophosphate pesticides such as chlorpyrifos in surface water in agricultural areas often exceed the standard by 10-100 times.

[0003] Current water treatment technologies face multiple bottlenecks in removing pesticide residues. Physical adsorption methods (such as activated carbon and clay minerals), while simple to operate, pose a risk of secondary pollution after adsorption saturation. Studies have shown that waste activated carbon loaded with dichlorvos can release up to 23% of its initial adsorbed pesticide residue in landfill leachate. Biodegradation methods rely on microbial metabolic activity, resulting in low efficiency in degrading highly toxic pesticides. For example, activated sludge systems in wastewater treatment plants typically achieve a removal rate of less than 40% for pyrethroid pesticides, with degradation cycles exceeding 72 hours. More seriously, some pesticide intermediates are more toxic than the parent compound; for instance, the degradation of parathion produces paraoxon, increasing its toxicity by up to 300%.

[0004] Advanced oxidation technologies are considered an effective way to solve recalcitrant pollutants. Oxygen vacancies, as catalytic active sites, can accelerate the decomposition of H2O2 to generate hydroxyl radicals. The homogeneous Fenton process uses ferrous ions to catalyze the generation of hydroxyl radicals from hydrogen peroxide, which can degrade a variety of organic pollutants. However, this method has inherent drawbacks: firstly, the reaction needs to be carried out under strongly acidic conditions with a pH ≤ 3, requiring continuous acidification of actual water bodies, increasing treatment costs by more than 45%; secondly, the amount of iron sludge produced after the reaction reaches 150-300 mg / L, becoming a new solid waste. Although heterogeneous Fenton catalysts (such as supported iron oxides) broaden the applicable pH range, the dissolution rate of active sites exceeds 5 mg / L under neutral conditions, still making it impossible to avoid metal ion leakage.

[0005] The emergence of nanozyme materials has provided new insights into water treatment. These nanomaterials, possessing enzyme-like catalytic activity, can mimic the catalytic mechanism of natural peroxidases to degrade pollutants. Carbon-based nanozymes (such as graphene oxide) possess high specific surface area and electron mobility, but single-carbon materials exhibit significant limitations in peroxidase activity. While metal oxide nanozymes (such as Fe3O4 and CeO2) demonstrate catalytic potential, their aggregation effect reduces the number of effective active sites. Experimental data show that after three reuses, unmodified Fe3O4 nanoparticles experience a 62% decrease in specific surface area due to aggregation, resulting in a more than 50% reduction in catalytic efficiency.

[0006] Current nanozyme application systems suffer from three key drawbacks: First, it is difficult to balance catalytic activity and stability. Increasing the metal loading can enhance activity, but the dissolution rate of metal particles during the reaction also increases. Second, the synergistic mechanism between the support and the active component is unclear. Most studies employ physical mixing methods to composite carbon materials and metal oxides, failing to establish effective electron transport channels. Finally, there is a lack of process control strategies for complex water quality conditions. Different pesticides have significantly different molecular structures, and existing technologies have not yet established universal models for key parameters such as oxidant dosage and reaction kinetics control.

[0007] Breakthroughs are urgently needed in the material design and process control of water pesticide residue treatment technologies to meet the triple requirements of high efficiency, stability, and wide adaptability. Summary of the Invention

[0008] The purpose of this invention is to provide a method for the catalytic degradation of pesticide residues using nanozymes. Nanozyme materials refer to catalytic materials composed of transition metal oxides and carbon-based composite supports, possessing peroxidase-like activity, and are used for the catalytic degradation of pesticide residues.

[0009] To achieve the above objectives, the present invention provides the following technical solution: A method for the catalytic degradation of pesticide residues in water using nanozymes includes the following steps: Nanoenzyme materials, composed of transition metal oxides and carbon-based composite carriers, with a specific surface area of ​​200 m², are added to water bodies containing pesticide residues. 2 / g to 500m 2 / g; Add hydrogen peroxide to the water to a final concentration of 0.1 mmol / L to 5 mmol / L; The reaction was carried out at a pH of 4.0 to 10.0 and a temperature of 20°C to 50°C for 30 to 120 minutes with stirring at 100 to 500 rpm. The transition metal oxide comprises a binary or ternary composite oxide formed by at least two of the metal elements selected from iron, copper, and cobalt, and the metal elements account for 5% to 15% of the total mass of the nanoenzyme material.

[0010] Furthermore, the carbon-based composite carrier is selected from at least one of graphene, carbon nanotubes, and biochar, and the carrier pore size is 2-15 nm.

[0011] Furthermore, the binary or ternary composite oxide is Fe3O4-CuO, Fe3O4-Co3O4, or Fe3O4-CuO-Co3O4.

[0012] Furthermore, the oxygen vacancy concentration of the nanozyme material is 18% to 25%.

[0013] Furthermore, the dosage of the nanozyme material is from 0.1 g / L to 1 g / L in water.

[0014] Furthermore, the stirring speed is 200 rpm to 400 rpm.

[0015] Furthermore, the pesticide residue is an organophosphate, pyrethroid, or carbamate pesticide.

[0016] An apparatus for implementing a method for catalytic degradation of pesticide residues in water using nanozymes, comprising: Reaction vessel; A magnetic separation device includes a permanent magnet array disposed at the bottom of a reaction vessel, wherein the permanent magnet array generates a magnetic field strength of 0.5T to 1.5T, corresponding to a nanozyme recovery rate of ≥95%; The pH online monitoring instrument has a probe that extends into the reaction vessel. The temperature control unit includes a thermoelectric cooler attached to the outer wall of the reaction vessel and a PID controller. The PID controller receives temperature sensor signals in real time and adjusts the power of the thermoelectric cooler.

[0017] The beneficial effects of this invention are as follows: 1. Synergistic improvement in material activity and stability. The transition metal oxide and carbon-based support form a chemically bonded interface, increasing the dispersion of the active metal to over 85%. The interfacial bonding energy between Fe3O4 and graphene reaches 2.8 J / m. 2 This effectively inhibits the migration and aggregation of metal particles. The oxygen vacancy concentration is controlled within the 18-22% range, ensuring continuous exposure of the enzyme-like catalytic active sites. Copper enhances the generation rate of hydroxyl radicals by forming Fe-Cu synergistic active sites. After 10 cycles, the material exhibits a surface area decay rate of less than 8%, and metal leaching is controlled below 0.2 mg / L, overcoming the bottleneck of poor reusability in traditional nanozymes.

[0018] 2. Wide pH-adaptive catalytic mechanism. The synergistic proton regulation between carboxyl groups and metal hydroxyl groups on the carbon support surface ensures highly efficient catalysis within the pH range of 4-10. Under neutral conditions (pH 6.5-7.5), graphene's electron buffering capacity maintains peroxidase activity at 92% of its maximum activity. This extends the pH application window by more than three times compared to the traditional Fenton process, eliminating the need for acid / base adjusters and reducing processing costs by 40%.

[0019] 3. Versatile degradation capability against multiple pesticides. Addressing the differences in PO bond energy (265 kJ / mol) for organophosphates, C-Cl bond energy (327 kJ / mol) for pyrethroids, and CN bond energy (305 kJ / mol) for carbamates, the nanopores selectively enrich pollutant molecules. The hydroxyl radical generation rate reaches 4.7 × 10⁻⁶. -7 It has a mol / L·s concentration and a degradation rate of over 90% for all three types of pesticides within 60 minutes, with a half-life shortened to 1 / 15 of that of conventional biological treatment.

[0020] 4. Optimization of process energy and resource consumption. A magnetic permanent magnet array achieves a 98.5% recovery rate of nano-enzymes, reducing catalyst replenishment to 0.01 g / ton of water. A semiconductor cooling chip combined with PID control achieves a temperature fluctuation range of ±0.3℃, saving 62% energy compared to mechanical stirring temperature control. H2O2 utilization is increased to 88.3%, reducing oxidant dosage by 35% compared to a homogeneous system.

[0021] 5. No secondary pollution emissions. Organophosphorus pesticides are degraded into phosphate ions, with a detection limit of 0.05 mg / L; pyrethroids undergo ring-opening to form biodegradable small molecules with a molecular weight of less than 200 Da. The TOC removal rate is stable at 75-82%, far exceeding the less than 45% of biological methods and 0% of adsorption methods. No iron sludge is generated during the entire reaction process, and the sludge reduction rate is 100%.

[0022] 6. Equipment Integration and Automation. The online pH monitor provides real-time data feedback to the control system, enabling dynamic optimization of reaction conditions. The gradient magnetic field design of the permanent magnet array (0.8-1.2T) adapts to the recovery of nanoenzymes with different particle sizes. The entire system occupies only 1 / 5 the area of ​​a biological treatment system and can process 10m³ of material. 3 The overall operating cost of the water body is less than 2.3 yuan. Attached Figure Description

[0023] Figure 1 This is a structural characterization diagram of nanozyme materials.

[0024] Figure 2 This is a process flow diagram of a nanozyme-catalyzed degradation method for pesticide residues in water.

[0025] Figure 3 This is a schematic diagram of the degradation equipment.

[0026] In the diagram: 301, reactor; 302, permanent magnet array; 303, temperature control system; 304, PID controller; 305, pH monitoring. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0028] Example 1: Degradation of dichlorvos by Fe3O4-CuO / graphene Material preparation Raw material ratio: FeCl3·6H2O (Sinopharm Group, purity ≥99%): 0.1 mol; CuCl2·2H2O (Alfa Aesar, purity ≥99.9%): 0.05 mol; Graphene oxide (Nanjing Xianfeng Nano, thickness 3-5nm, BJH method, specific surface area 800m² / g): 5g; Solvent: 200 mL of deionized water.

[0029] Synthesis process: 1. Precursor dispersion: Dissolve FeCl3·6H2O and CuCl2·2H2O in deionized water and disperse using an ultrasonic processor (500W power, 40kHz frequency) for 30 minutes to form a homogeneous solution.

[0030] 2. Carrier loading: Add graphene oxide and continue ultrasonic dispersion for 1 hour to ensure uniform suspension of the carrier.

[0031] 3. Coprecipitation reaction: Under 80℃ oil bath conditions, 1mol / L NaOH solution is added dropwise until pH=10.0, and mechanical stirring is carried out for 1 hour to form hydroxide precipitate.

[0032] 4. Hydrothermal crystallization: Transfer the reaction solution to a 500mL stainless steel high-pressure reactor (Parr4560) and perform hydrothermal reaction at 180℃ for 12 hours to promote crystal growth.

[0033] 5. Post-processing: The product was collected by magnetic separation (neodymium iron boron magnet, magnetic field strength 1.2T), washed three times with ethanol (200mL each time), and dried under vacuum at 60℃ for 24 hours.

[0034] Material characterization: Composition analysis: The Fe-Cu loading was determined to be 12.3% by ICP-OES (Agilent 720ES), and the Fe:Cu atomic ratio was 2:1.

[0035] Structural characteristics: BET specific surface area 325m 2 / g(Micromeritics ASAP2020); The oxygen vacancy concentration was determined to be 22.1% by XPS (Thermo Fisher ESCALAB Xi+) (O1s peak fitting, peak area percentage at binding energy 530.5 eV).

[0036] Degradation experiment Reaction system: Equipment: 1L glass reactor 301 (built-in permanent magnet array 302, magnetic field strength 1.2T, Shanghai Shensheng Technology), equipped with pH online monitor 305 (Mettler Toledo SevenMulti) and temperature control system 303, the temperature control system 303 contains semiconductor cooling chip (model TEC1-12706) and PID controller 304 (accuracy ±0.3℃).

[0037] Simulated wastewater: Dichlorvos (99% standard, Dr. Ehrenstorfer) concentration 10 mg / L, pH 6.5 (adjusted with 0.1 mol / L phosphate buffer).

[0038] Dosing parameters: Nanozyme material: 0.5 g / L; H2O2 (30% solution, Sigma-Aldrich): 2 mmol / L.

[0039] Reaction conditions: Temperature: 40℃; Stirring speed: 400 rpm (IKA RCT basic); Reaction time: 60 minutes; Analysis method: Pesticide residues: LC-MS / MS (Agilent 6470, GB23200.113-2018), column: ZORBAX Eclipse Plus C18 (2.1×100mm, 1.8μm), mobile phase: acetonitrile-water (containing 0.1% formic acid) gradient elution.

[0040] TOC removal rate: TOC analyzer (Shimadzu TOC-L).

[0041] Metal leaching: ICP-MS (Agilent 7900, EPA 6020B), internal standard:115 In and 193 Ir.

[0042] Experimental results: The degradation rate of dichlorvos reached 95.2%±1.1%, and the TOC removal rate was 78.5%±2.3%.

[0043] The iron leaching amount was 0.18 mg / L ± 0.02, and the copper leaching amount was 0.05 mg / L ± 0.01, both of which were lower than the limits set by the "Surface Water Environmental Quality Standard" (GB3838-2002).

[0044] Material recycling and regeneration Magnetic separation efficiency: When a 1.2T magnetic field is applied for 5 minutes, the material recovery rate is 98.7% (gravimetric method).

[0045] Regeneration process: The recycled material is soaked in 0.1 mol / L NaOH solution for 30 minutes, washed with deionized water until neutral, and then vacuum dried for reuse.

[0046] Cyclic stability: After 10 consecutive uses, the degradation rate of dichlorvos still remained at 89.3% (RSD=2.5%), demonstrating excellent cyclic performance.

[0047] Example 2: Fe3O4-Co3O4 / carbon nanotubes degrade chlorpyrifos Material preparation Raw material ratio: FeCl3·6H2O: 0.05 mol; CoCl2·6H2O (Sinopharm Group, purity ≥99%): 0.05 mol; Multi-walled carbon nanotubes (Nanjing Xianfeng Nano, length 10-30μm, outer diameter 10-20nm): 3g; Synthesis process: 1. Precursor dispersion: FeCl3 and CoCl2 were dissolved in 150 mL of deionized water and ultrasonically dispersed for 30 minutes.

[0048] 2. Carrier loading: Add carbon nanotubes and mechanically stir for 2 hours to ensure uniform loading.

[0049] 3. Coprecipitation reaction: Add 1 mol / L NaOH dropwise until pH=11.0, stir in an oil bath at 60℃ for 2 hours.

[0050] 4. Hydrothermal crystallization: react at 180℃ for 12 hours, and the post-treatment is the same as in Example 1.

[0051] Material characterization: Fe:Co molar ratio 1:1, loading 10.8% (ICP-OES).

[0052] BET has a specific surface area of ​​410 m² / g and an oxygen vacancy concentration of 18.5% (XPS).

[0053] Degradation experiment Reaction system: Chlorpyrifos (98% standard, AccuStandard) concentration 15 mg / L, pH 8.0 (Tris-HCl buffer).

[0054] Dosage: Nanozyme 0.3 g / L, H2O2 1.5 mmol / L.

[0055] Reaction conditions: Temperature: 30℃; Stirring speed: 300 rpm; Reaction time: 120 minutes.

[0056] Experimental results: The degradation rate of chlorpyrifos was 93.7% ± 1.3%, and the amount of Co leached was 0.15 mg / L ± 0.03.

[0057] Example 3: Degradation of Cypermethrin by a Ternary Complex Raw material ratio: FeCl3·6H2O: 0.1 mol; CuCl2·2H2O: 0.05 mol; CoCl2·6H2O: 0.05 mol; Rice husk biochar (self-made, pore size 5-10nm, specific surface area 200m²) 2 / g): 8g. Rice husk biochar was prepared by the following method: (1) After being crushed and acid-washed, the rice husks were carbonized at 600℃ for 2 hours under N2 protection; (2) CO2 activation at 800℃ for 1 hour yielded pores with a diameter of 5-10 nm and a specific surface area of ​​200 m². 2 / g of biochar carrier.

[0058] Synthesis process: 1. Precursor dispersion: Fe 3+ Cu 2+ Co 2+ Mixed solution (total concentration 0.2 mol / L).

[0059] 2. Carrier loading: Add rice husk biochar and ultrasonically disperse for 1 hour.

[0060] 3. Coprecipitation reaction: pH=9.0, stir at 70℃ for 3 hours.

[0061] 4. Hydrothermal crystallization: react at 180℃ for 12 hours, and the post-treatment is the same as in Example 1.

[0062] Material characterization: Fe:Cu:Co molar ratio 2:1:1, loading 14.2% (ICP-OES).

[0063] BET specific surface area 285m 2 / g, oxygen vacancy concentration 24.3% (XPS).

[0064] Degradation experiment Reaction system: Cypermethrin (99% standard, Sigma-Aldrich) concentration 20 mg / L, pH 4.0 (citrate buffer).

[0065] Dosage: 1 g / L nanozyme, 25 mmol / L H2O.

[0066] Reaction conditions: Temperature: 50℃; Stirring speed: 500 rpm; Reaction time: 90 minutes.

[0067] Experimental results: Cypermethrin degradation rate was 96.8% ± 1.5%, through 13 C isotope tracing method verifies that the adsorption contribution of carbon-based supports is <5%.

[0068] Example 4: Validation of Low-Oxygen Vacancy Materials Material preparation: The process of Example 1 was adjusted to reduce the hydrothermal reaction temperature to 150°C (other conditions remained unchanged).

[0069] Characterization results: Oxygen vacancy concentration: 15.8% (XPS fitting, same method as in Example 1); BET specific surface area: 298m² 2 / g.

[0070] Degradation experiment (same conditions as in Example 1): Degradation rate of dichlorvos: 85.3% ± 1.8% (60 minutes); Activity after 10 cycles: 80.1%.

[0071] Comparative Example 1 Material preparation: FeCl3·6H2O is 0.1 mol, graphene oxide is 5 g, and CuCl2 is omitted.

[0072] Load capacity 12.5%, specific surface area 310 m² 2 / g, oxygen vacancy concentration 15.2%.

[0073] Degradation results: The degradation rate of dichlorvos was 67.8% (60 minutes), and the iron leaching amount was 2.3 mg / L, which was significantly higher than that in Example 1.

[0074] Comparative Example 2 Preparation process: After hydrothermal reaction, argon annealing at 600℃ for 2 hours reduced the oxygen vacancy concentration to 8.3%.

[0075] Degradation results: The degradation rate of dichlorvos was 58.6% (60 minutes), and the activity decreased by 42% after 5 repetitions, showing the key role of oxygen vacancies in catalytic activity.

[0076] Comparative Example 3 Equipment improvements: The switch-type temperature control (temperature fluctuation ±5℃) is adopted, eliminating the need for a PID controller.

[0077] Degradation results: The degradation rate of dichlorvos fluctuated between 82.3% and 90.1%, and the ineffective decomposition rate of H2O2 increased to 35%, demonstrating the importance of precise temperature control for reaction efficiency.

[0078] Validation of experimental data integrity Methodological validation: Repeatability verification: Example 1 was independently repeated 5 times, and the degradation rate RSD was 1.8% (LC-MS / MS), showing the high reliability of the experimental results.

[0079] Testing standards: Pesticide residues: GB23200.113-2018 (LC-MS / MS).

[0080] Industrial-grade verification Pilot-scale: 10 tons / day treatment system (wastewater from a pesticide factory in Jiangsu).

[0081] Operating parameters: The influent concentration of dichlorvos was 20 mg / L, and the pH was 7.0. Dosage: Nanozyme 0.6 g / L, H2O2 3 mmol / L; Duration of stay: 90 minutes; Execution result: Average degradation rate: 93.5% (72 hours of continuous operation); The cost per ton of water is 0.23 yuan (including material loss and H2O2 cost).

[0082] Table 1: Aperture Comparison Experiment Table *Note: The interlayer spacing of graphene is considered as the equivalent pore size.

[0083] Conclusion: When the carrier pore size is 2-15 nm, the degradation rate can be increased by >25% due to matching the size of pesticide molecules (DDVP: 0.8 nm; chlorpyrifos: 1.2 nm).

[0084] The structural characterization diagram of the nanoenzyme material is shown below. Figure 1 The process flow diagram for the nanozyme-catalyzed degradation of pesticide residues in water is shown below. Figure 2 A schematic diagram of the degradation equipment can be found here. Figure 3 .

[0085] The above description is merely a preferred embodiment of the present invention; however, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and its improved concepts, should be covered within the scope of protection of the present invention.

Claims

1. A method for the catalytic degradation of pesticide residues in water using nanozymes, characterized in that, Includes the following steps: Nanoenzyme materials, composed of transition metal oxides and carbon-based composite carriers, with a specific surface area of ​​200 m², are added to water bodies containing pesticide residues. 2 / g to 500m 2 / g; Add hydrogen peroxide to the water to a final concentration of 0.1 mmol / L to 5 mmol / L; The reaction was carried out at a pH of 4.0 to 10.0 and a temperature of 20°C to 50°C for 30 to 120 minutes with stirring at 100 to 500 rpm. The transition metal oxide comprises a binary or ternary composite oxide formed by at least two of the metal elements selected from iron, copper, and cobalt, and the metal elements account for 5% to 15% of the total mass of the nanoenzyme material.

2. The method for catalytic degradation of pesticide residues in water by nanozymes according to claim 1, characterized in that, The carbon-based composite carrier is selected from at least one of graphene, carbon nanotubes, and biochar, and the carrier pore size is 2-15 nm.

3. The method for catalytic degradation of pesticide residues in water using nanozymes according to claim 1, characterized in that, The binary or ternary composite oxide is Fe3O4-CuO, Fe3O4-Co3O4, or Fe3O4-CuO-Co3O4.

4. The method for catalytic degradation of pesticide residues in water by nanozymes according to claim 1, characterized in that, The oxygen vacancy concentration of the nanozyme material is 18% to 25%.

5. The method for catalytic degradation of pesticide residues in water by nanozymes according to claim 1, characterized in that, The dosage of the nanozyme material is 0.1 g / L to 1 g / L in water.

6. The method for catalytic degradation of pesticide residues in water by nanozymes according to claim 1, characterized in that, The stirring speed is 200 rpm to 400 rpm.

7. The method for catalytic degradation of pesticide residues in water by nanozymes according to claim 1, characterized in that, The pesticide residues are organophosphates, pyrethroids, or carbamates.

8. An apparatus for implementing the method of nanozyme catalytic degradation of pesticide residues in water as described in claim 1, characterized in that, include: Reaction vessel; A magnetic separation device includes a permanent magnet array (302) disposed at the bottom of a reaction vessel (301), wherein the permanent magnet array (302) generates a magnetic field strength of 0.5T to 1.5T, corresponding to a nanozyme recovery rate of ≥95%; The pH online monitoring instrument (303) has a probe that extends into the reaction vessel; The temperature control unit (304) includes a thermoelectric cooler attached to the outer wall of the reaction vessel and a PID controller (305), wherein the PID controller (305) receives temperature sensor signals in real time and adjusts the power of the thermoelectric cooler.

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