Process for preparing nano titanium dioxide adsorption material by adopting sol-gel method

Abstract

The invention relates to the technical field of adsorption material preparation, and discloses a process for preparing a nano titanium dioxide adsorption material by adopting a sol-gel method, which comprises the following steps: dispersing a diatomite carrier in a non-alcohol organic solvent to form a suspension, and performing grafting reaction under the condition of no liquid water to obtain the nano titanium dioxide adsorption material. Monitoring physical properties representing accumulation of the alcohol by-products by using an online physical sensor, and determining a first change rate of the physical properties; when the first change rate is lower than a first preset rate threshold value, introducing gas containing water vapor to execute a hydrolysis reaction, continuously monitoring the physical properties and determining a second change rate; and when the second change rate is lower than a second preset rate threshold value, the hydrolysis reaction is terminated, through the process path, the active components grow in situ on the chemical bonding anchor points, a high-stability chemical bonding structure is formed, and the problems of active component loss and secondary pollution caused by physical adsorption are avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to a process for preparing nano-titanium dioxide adsorption material by sol-gel method, and belongs to the technical field of adsorption material preparation. BACKGROUND

[0002] Currently, the physical structure of natural porous carriers such as diatomite is used to load active components such as nano-titanium dioxide in situ by sol-gel chemical method, which is a common technical method combining carrier stability and high specific surface area of active components; a common process is to immerse diatomite carriers in an organic solution of titanium alkoxide precursor, drop liquid water into the solution, and initiate hydrolysis and precipitation of the precursor in the pore channels of the carrier; the process relies on the assumption that the pore structure of the carrier can physically constrain the agglomeration and loss of nanoparticles, but in the face of high flow rate and long-term scouring in industrial application scenarios, active components that are not strongly combined with the carrier are prone to secondary dissolution, not only making the adsorption material ineffective, but also the lost particles themselves constituting a new source of pollution; the reason lies in the reaction characteristics at the colloidal chemistry level, in the presence of liquid water, the reaction rate of the self-condensation reaction between the hydrolysis products of titanium alkoxide is much higher than that of the heterogeneous grafting reaction with the hydroxyl groups on the surface of diatomite carriers.

[0003] To avoid this problem or try to introduce a high molecular binder to enhance adhesion, such methods not only fail to fundamentally solve the lack of chemical bonding, but also introduce new instability factors, for example, a Chinese invention patent with publication number CN106757374A discloses a method for depositing titanium dioxide whiskers using titanium dioxide sol, the technical idea of which is to mix titanium dioxide sol with PVA template, form whiskers through hydrothermal reaction, then mix in resin and high molecular weight PVA as a binder, and finally attach the whiskers to air filter material through impregnation method; the essence of this method is to rely on the physical coating effect of the high molecular binder to fix the whiskers, rather than realizing chemical bonding between the active components and the carrier substrate; when the binder ages and fails under long-term scouring or complex working conditions, the whiskers will fall off, leading to the same secondary pollution problem.

[0004] Therefore, how to provide a process method that can reconfigure the reaction path, avoid the above rate competition at the kinetic level, and enable heterogeneous grafting of active components and carrier surfaces to occur preferentially, has become a technical problem to be solved by the present application. SUMMARY

[0005] The present application provides a process for preparing nano-titanium dioxide adsorption material by sol-gel method, which mainly aims to solve the problem of reaction rate difference in the existing sol-gel process, i.e., the self-condensation rate is much faster than the heterogeneous grafting rate due to liquid phase hydrolysis, and to reduce the physical adsorption of active components, thereby solving the problem of easy loss and failure of adsorption material under high flow rate conditions and causing secondary pollution.

[0006] To achieve the above object, the present application provides a process for preparing nano-titanium dioxide adsorbent material by sol-gel method, comprising the following steps:

[0007] Step 101, dispersing the diatomite carrier after drying treatment in non-alcohol organic solvent containing titanium alkoxide precursor to form a suspension;

[0008] Step 102, under the condition of no liquid water addition, maintaining the suspension to perform grafting reaction for releasing alcohol by-product, meanwhile, monitoring the physical property characterizing the accumulated concentration of alcohol by-product by online physical sensor in real time, and determining the first change rate based on the physical property;

[0009] Step 103, when the first change rate is lower than the first preset rate threshold, determining that the grafting reaction is terminated, and starting to pass the gas containing water vapor into the suspension to perform hydrolysis reaction for releasing alcohol by-product, meanwhile, continuously monitoring the physical property by online physical sensor, and determining the second change rate based on the physical property;

[0010] Step 104, when the second change rate is lower than the second preset rate threshold, determining that the hydrolysis reaction is terminated, and starting the separation and drying step to obtain nano-titanium dioxide adsorbent material.

[0011] Preferably, the gas containing water vapor in step 103 also contains volatile catalyst vapor, and the preparation step of the gas comprises: passing carrier gas through constant temperature bath containing water solution of volatile catalyst.

[0012] Preferably, the physical property is the refractive index of the suspension, and the online physical sensor is online refractometer.

[0013] Preferably, the physical property is the viscosity of the suspension, and the online physical sensor is online viscometer.

[0014] Preferably, the water solution of volatile catalyst is acetic acid aqueous solution.

[0015] Preferably, the water solution of volatile catalyst is ammonia water.

[0016] Preferably, the first change rate and the second change rate are calculated according to the following formula: wherein, is the first change rate or the second change rate, is the preset time window, is the current time measurement value of the physical property, is the previous time measurement value of the physical property, and the time interval between the current time measurement value and the previous time measurement value is .

[0017] Preferably, the process further comprises, before step 101, a step 801 of pretreating the dried diatomite carrier with a silane coupling agent to construct functional groups on the surface of the dried diatomite carrier; and the dried diatomite carrier in step 101 is the dried diatomite carrier pretreated in step 801.

[0018] Preferably, the non-alcohol organic solvent is an aromatic hydrocarbon solvent.

[0019] Preferably, the non-alcohol organic solvent is an aromatic hydrocarbon solvent.

[0020] Compared with the prior art, the present application has the following advantages:

[0021] 1. By the grafting step performed under the condition of no liquid water, the chemical bonding anchor points are first established on the surface of the diatomite carrier, which avoids the homogeneous nucleation and self-condensation of the precursor in the liquid phase from the reaction path; then by the way of water vapor, the mass transfer rate is used to control the progress of the hydrolysis reaction, so that the hydrolysis and growth are guided to occur in situ on the bonded anchor points, and finally the chemical bonding is formed between the carrier and the active component instead of physical adsorption.

[0022] 2. The nano-titanium dioxide active component is formed by chemical bonding from the surface of the diatomite carrier, instead of the physical accumulation or pore blockage in the traditional process; this structural difference makes the active component and the carrier have high stability, and when facing high flow rate fluid scouring or long-term operation, the secondary dissolution and loss of the active component can be avoided; the adopted gas phase controlled hydrolysis method limits the reaction rate to the supply rate of water vapor, avoiding the explosive precipitation caused by the traditional liquid phase water addition; this controlled growth mechanism makes the nano-titanium dioxide uniformly coated in the form of a thin film or an oligolayer on the inner wall of the pores of the diatomite, instead of forming agglomerates to block the pores, which realizes the exposure of high active sites while maintaining the original porous filtration and mass transfer performance of the diatomite carrier. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The process flow chart of the nano-titanium dioxide adsorption material prepared by the present application based on online physical sensor closed-loop control;

[0024] Figure 2 The corresponding relationship diagram of the precursor concentration and the change rate R in the online monitoring of the present application;

[0025] Figure 3 The functional architecture schematic diagram of the data analysis platform for realizing the closed-loop process control of the present application. DETAILED DESCRIPTION

[0026] In order to make the objectives, technical solutions and advantages of the present application clearer, further detailed description will be made to the present application in combination with the accompanying drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and should not be used to limit the protection scope of the present application.

[0027] The present application provides a process for preparing nano-titanium dioxide adsorption material by sol-gel method. Through two-stage process monitored and closed-loop controlled by online physical sensor in real time, it is ensured that nano-titanium dioxide active component preferentially forms chemical bonding with diatomite carrier instead of traditional physical adsorption; grafting reaction is performed under liquid water-free condition to establish chemical anchor point, and in-situ hydrolysis growth is performed under controlled water vapor supply, the whole process accurately determines the reaction endpoint by monitoring the physical property change caused by the accumulation of alcohol by-products, thereby solving the problems of active component loss and secondary pollution; in a specific embodiment, the process involves pretreatment of raw material diatomite carrier. Since the density and activity state of surface hydroxyl (Si-OH) of diatomite batches are not uniform, which constitutes the non-uniform interface of subsequent grafting reaction, in order to solve this problem, before step 101, step 801 can be preferably included, that is, the dried diatomite carrier is pretreated by silane coupling agent; specifically, the reason why the grafting reaction can significantly improve the reaction rate under liquid water-free and catalyst-free conditions is that: step 801 converts the low-activity silicon hydroxyl on the surface of diatomite into functional groups with high nucleophilic activity, such as amino propyl containing lone pair of electrons, etc. In the non-polar solvent system without liquid water and external catalyst, this introduced functional group not only serves as a chemical bonding anchor point, but also acts as an in-situ basic catalytic center. Since the functional groups such as amino have strong nucleophilic attack tendency to the central titanium atom of titanium alkoxide, they can reduce the reaction activation energy by forming a coordination transition state, thereby inducing heterogeneous grafting reaction to occur preferentially over homogeneous condensation reaction at the kinetic level, ensuring that the chemical anchor point is saturated before hydrolysis; in step 101, the diatomite carrier pretreated by step 801 or not pretreated and dried is dispersed in a non-alcohol organic solvent containing titanium alkoxide precursor (for example, tetrabutyl titanate Ti(OBu)4) to form a suspension; the selection of the solvent is critical here, which must be a non-alcohol organic solvent, because the core of the subsequent process is to monitor the accumulation of alcohol by-product (ROH, in this case, butanol), if alcohol solvent is used as the background, the trace accumulation of by-product will be covered by the bulk solvent background, resulting in monitoring failure, therefore, a non-alcohol solvent with different physical properties from butanol is preferably used, such as alkane solvent (e.g. hexane, heptane) or aromatic hydrocarbon solvent (e.g. toluene, xylene), the selection of such solvent makes the accumulation of by-product butanol (polar) change the physical properties of the whole suspension system (non-polar).

[0028] Next, step 102 is performed to maintain the suspension (e.g., at 50 °C) without adding liquid water. (Stirring) to perform the grafting reaction that releases alcohol byproducts; this step is the first key stage of this process. The absence of liquid water kinetically inhibits the rapid self-condensation of the titanium alkoxide precursor in the solution phase (Ti-O-Ti), and instead preferentially causes it to undergo a slower heterografting reaction with functional groups on the support surface (such as pretreated -NH2 or natural -OH) (e.g., Ti-OR+H2N-Si->Ti-NH-Si+ROH). This reaction plants chemical bonding anchors on the support surface, releasing alcohol byproducts (ROH). Meanwhile, an online physical sensor is used to monitor in real time the physical properties characterizing the cumulative concentration of alcohol byproducts. In this embodiment, the physical property is the refractive index of the suspension, and the online physical sensor is an online refractive index meter. Due to the difference in refractive index between butanol and toluene, the trace accumulation of butanol will cause a precisely measurable change in the total refractive index of the suspension. Experimental calibration shows that, in a reaction system at 50°C, the volume fraction of the byproduct butanol in the non-alcohol solvent exhibits a highly linear and unique quantitative relationship with the refractive index of the suspension. The linear correlation coefficient is obtained by least squares fitting. All values ​​are greater than 0.998, proving that there is a unique and repeatable mapping logic between the change in physical property and the chemical reaction process; in another embodiment, the physical property is the viscosity of the suspension, and the online physical sensor is an online viscometer; the control system continuously measures the macroscopic physical property ( Determine the first rate of change ( The calculation of this rate is based on a deterministic procedure, namely... ,in, The first rate of change, For a preset time window (e.g., 1 minute). The physical properties are measured at the current moment. These are the physical properties measured at the previous moment; in the initial stage of the grafting reaction, the reaction occurs, and ROH is continuously released. change, Maintaining a non-zero level, as the active sites on the carrier surface are gradually filled, the grafting reaction tends to saturate, and the ROH release rate decreases. The value also decreases accordingly. Due to the uneven distribution and low activity of natural hydroxyl groups on the diatomaceous earth surface, this process introduces a silane coupling agent (such as APTES) in step 801 to construct a high density of aminopropyl functional groups on the support surface. During the anhydrous grafting process in step 102, the nucleophilic substitution reaction rate between the titanium alkoxide precursor and the functionalized surface is much higher than the condensation rate of traditional Si-OH. The first rate of change captured by the online physical sensor... It can accurately reflect the changes in the concentration of alcohol byproducts generated in this process, when < When the time is reached, it indicates that the active sites on the carrier surface have achieved chemical bonding saturation.

[0029] Execute step 103, when the first rate of change ( When the rate falls below the first preset threshold, the control system determines that the grafting reaction has terminated and immediately initiates the introduction of water vapor-containing gas into the suspension to perform a hydrolysis reaction that releases alcohol byproducts. This is the second key stage of the process, namely gas-phase rate-controlled hydrolysis. By introducing water vapor instead of liquid water, the water supply rate is limited to the gas-liquid mass transfer rate, becoming the rate-limiting step of the entire hydrolysis reaction. This controlled, slow water molecule supply avoids the explosive precipitation caused by traditional liquid-phase water addition, instead forcibly guiding the hydrolysis reaction (e.g., The hydrolysis process preferentially occurs and grows in situ on the chemically bonded anchor sites already formed on the support surface in step 102. This hydrolysis step also releases alcohol byproducts (ROH). During step 103, an online physical sensor continuously monitors the physical properties, and the control system continuously determines the second rate of change based on the physical properties. In a preferred embodiment, the gas containing water vapor also contains volatile catalyst vapor. The preparation steps include: passing a carrier gas (e.g., dry nitrogen) at a controlled flow rate (e.g., 100 mL / min) through a constant-temperature bath (e.g., 40 °C) containing an aqueous solution of the volatile catalyst. If the aqueous solution of the volatile catalyst is acetic acid, the carrier gas will simultaneously carry H2O(g) and CH3COOH(g), achieving rate-controlled growth under acid catalysis; if it is ammonia, rate-controlled growth under alkali catalysis will be achieved. This gas-phase co-transport method, without disrupting mass transfer control, utilizes the catalyst to accelerate the surface growth reaction rate at the anchored sites, improving process efficiency. Finally, step 104 is executed. During the hydrolysis growth process in step 103, as the -OR groups on the anchored sites are gradually hydrolyzed, the release rate of ROH decreases again, and the second rate of change ( The rate of change also decreases accordingly; when the second rate of change is lower than the second preset rate threshold (e.g.) It may be equal to or different from When the hydrolysis reaction is terminated, the control system determines that the hydrolysis reaction has ended and initiates separation (such as filtration, centrifugation) and drying (such as 80°C). The process involves an oven drying step to obtain a nano-titanium dioxide adsorbent material in which the final active component is chemically bonded and anchored on a diatomaceous earth carrier.

[0030] Example 1: In a fixed-bed adsorption column system for treating high-throughput industrial wastewater, nano-titanium dioxide adsorbent material with diatomaceous earth as a carrier is used to remove specific pollutants from the water. Under long-term high-flow-rate conditions, such as exceeding the design flow rate by 20%, the adsorbent material prepared by the traditional liquid-phase water precipitation method exposed its structural defects. Specifically, in the early stage of system operation, the pressure difference of the downstream fine filtration system of the adsorption column was monitored to rise rapidly, and the concentration of nano-titanium dioxide particles (secondary pollutants) in the effluent continued to exceed the standard. This indicates that the active components fixed by physical adsorption and pore packing in the traditional process are detached and lost under the shear force of high-flow-rate fluid, leading to adsorption bed failure and causing secondary pollution. To address this operating condition, the system was upgraded to use the described process, employing a sol-gel method to prepare nano-titanium dioxide adsorbent materials. The preparation process strictly adheres to a two-stage reaction sequence and online monitoring and control. In this process, the design of the process path avoids rate competition between self-condensation and heterogeneous grafting. In the waterless grafting stage of step 102, the titanium alkoxide precursor is guided to the surface of the diatomaceous earth carrier pretreated in step 801 to undergo chemical bonding, forming anchoring points. The alcohol byproduct (butanol) released during this process accumulates in the non-alcohol solvent (toluene), causing a change in the refractive index of the suspension. This change is monitored in real time by an online refractive index meter, and the first rate of change is calculated. (in accordance with This provides the control system with the basis for determining whether the grafting reaction has been completed.

[0031] Only when the control system determines the first rate of change Below the first preset rate threshold ( After confirming that the chemical anchoring sites on the carrier surface have saturated and formed, the gas-phase rate-controlled hydrolysis in step 103 is triggered. This synergistic timing is a key step in ensuring the stability of the final product. Step 102 provides the substrate for the reaction in step 103, while the water vapor supply in step 103, which is limited by the mass transfer rate, ensures that the hydrolysis and growth reactions are confined to these bonded substrates in situ, rather than forming free particles in the solution phase. This hydrolysis stage also releases alcohol byproducts, and an online refractometer continuously monitors the resulting refractive index changes and calculates the second rate of change until the rate falls below the second preset rate threshold. This indicates that the growth reaction at the anchor point has also been completed. This two-step process of anchoring first and then growing, combined with an event-driven control method based on byproduct monitoring, ensures that the final nano-titanium dioxide active component grows from the diatomite surface through highly stable chemical bonds (such as Ti-O-Si or Ti-N-Si), rather than through physical accumulation. After replacing the adsorbent material with the one prepared by the process of this invention, the fixed-bed adsorption column system was put back into operation under continuous high-flow-rate scouring conditions. After several months of continuous operation, monitoring data showed that the removal rate of the target pollutant by the adsorption column remained at a high efficiency level without significant attenuation, the pressure difference of the downstream fine filtration system remained stable, and the concentration of nano-titanium dioxide particles in the effluent was always below the detection limit.

[0032] Example 2: To verify the technical effectiveness of the process of the present invention in constructing chemical bonds of active components and inhibiting secondary pollution, the following comparative experiment was set up; the experiment set up the sample group of the present invention and three control groups, namely control group A, control group B and control group C. The preparation of the sample group of the present invention strictly followed the two-stage process controlled by online physical sensors in the aforementioned specific embodiments; its key process procedures include: step 801, using aminopropyltriethoxysilane, i.e., APTES, to react the sample with 120... The dried diatomaceous earth carrier undergoes surface functionalization pretreatment; step 101, the pretreated carrier is dispersed in a non-alcoholic organic solvent containing tetrabutyl titanate, toluene in this embodiment; step 102, at 50 The waterless grafting reaction was carried out under stirring, while the refractive index of the suspension was monitored by an online refractometer, and based on... Calculate the first rate of change until Below the first preset rate threshold The threshold is set to Step 103: After determining that grafting has terminated, immediately introduce carrier gas (N2, 100 mL / min) through a 40-meter channel. A mixed gas containing water vapor and volatile catalyst vapor, prepared by a constant-temperature bath of a 1% v / v dilute acetic acid aqueous solution, was subjected to gas-phase rate-controlled hydrolysis, with continuous monitoring of the refractive index until the second rate of change. Below the second preset rate threshold The threshold is set to Step 104: Separate and dry; Control group A, used to simulate traditional process: adopts the traditional liquid phase water addition and one-step precipitation process in the background technology; specifically, the untreated product is subjected to 120... Dry diatomaceous earth carrier was dispersed in a toluene solution containing an equal amount of tetrabutyl titanate at 50 °C. Under stirring, liquid water equivalent to the total molar amount of water vapor in step 103 was slowly added dropwise. After the addition was complete, stirring was continued for the same total time. Finally, the mixture was separated and dried. Control group B, which lacked step 102, was used to verify the necessity of the liquid water-free grafting step. The preparation of this sample group skipped step 102. After performing step 101, the gas-phase rate-controlled hydrolysis of step 103 was performed immediately (the total hydrolysis time was the same as the time of step 103 in the sample group of this invention). Other steps were completely consistent with the sample group of this invention. Control group C, which lacked online monitoring, was used to verify the necessity of closed-loop control of online physical sensors. The preparation of this sample group used fixed time instead of event-driven, that is, the grafting reaction in step 102 was performed at 50°C. Stir for 1 hour without monitoring If the value is not specified, immediately proceed to step 103 (hydrolysis time is the same as the sample group of this invention), and the other steps are completely consistent with the sample group of this invention; stability (anti-leaching) test (dynamic leaching test): take 10.0g of each of the dried materials of the above-mentioned sample group of this invention and control groups A, B, and C, and pack them into four glass chromatographic columns of the same specification with an inner diameter of 1.5cm to form a fixed bed; A constant flow rate was maintained, and deionized water was continuously pumped in to simulate high-flow-rate flushing conditions. At the 72nd hour of system operation, the leachate from each adsorption column was collected, and the concentration of titanium (Ti) in the leachate was determined by inductively coupled plasma mass spectrometry (ICP-MS). This concentration directly characterizes the degree of loss of the active components of nano-titanium dioxide. The experimental results are shown in Table 1.

[0033] Table 1: Dynamic leaching test results of adsorbent materials prepared by different processes

[0034]

[0035] Referring to Table 1, the experimental data show that after 72 hours of high-flow-rate rinsing, the Ti concentration in the leachate of the sample group of this invention was below the detection limit of ICP-MS, i.e., 0.05 mg / L, confirming that no measurable loss of the active component occurred. The highest Ti loss concentration was observed in control group A (conventional process), reaching 12.62 mg / L, indicating that its physical adsorption structure was severely damaged under high flow rates. The Ti loss concentration in control group B (lacking the grafting step) was 8.17 mg / L, confirming that without the chemical anchoring in step 102, even with the gas-phase rate-controlled hydrolysis in step 103, the generated particles are mainly physically stacked and equally unstable. The Ti loss concentration in control group C (insufficient grafting time) was 5.44 mg / L, confirming that if the grafting reaction (step 102) is not monitored online (… To ensure its full completion, the remaining ungrafted precursor will still form a large number of unbonded and easily lost particles during the hydrolysis stage (step 103); and to further confirm the formation of chemical bonding anchor sites in step 102, the sample group of the present invention ends in step 102 (i.e., is determined). After (and before) the introduction of water vapor, a small amount of the support sample was taken for XPS characterization analysis: the characterization results showed that: There was obvious [something] nearby Orbital characteristic peaks, and in The energy spectrum was observed to belong to The shift peak of the binding energy (approximately) ); FTIR data comparison: Compared to pure diatomaceous earth, this intermediate sample in The area has been identified as belonging to The characteristic absorption band of stretching vibration; the above direct physical evidence confirms that, under anhydrous conditions, a high-density stable chemical bond structure has been successfully established on the carrier surface through the closed-loop control of this process, rather than a simple physical deposition.

[0036] Example 3: This example combines Figures 1 to 3 A process description for preparing nano-titanium dioxide adsorbent materials using the sol-gel method, such as... Figure 1 As shown, this process uses diatomaceous earth as a support, titanium alkoxide precursor, and non-alcoholic organic solvent as raw material inputs. Step 801 involves support pretreatment, where functional groups are constructed using a silane coupling agent. Step 101 prepares a suspension by dispersing the pretreated support in the solvent and precursor. Step 102 then proceeds to the grafting reaction stage, establishing chemical bonding points in the absence of liquid water. Step 103 involves hydrolysis, where steam and a possible catalyst are introduced for in-situ growth at the anchor points. The entire reaction process is monitored by an online physical sensor closed-loop control system. This system monitors physical properties such as refractive index or viscosity and calculates the rate of change. The system monitors the first rate of change. When judged At that time, the hydrolysis reaction in step 103 is initiated, and the second rate of change is monitored. When judged When the reaction is terminated, the separation and drying in step 104 are performed to obtain the final product, namely, a nano-titanium dioxide adsorbent material with high stability, chemical bonding, and anti-leakage properties.

[0037] like Figure 2As shown in the figure, the horizontal axis represents time (minutes / min), the left vertical axis represents precursor concentration (milligrams per liter / L), and the right vertical axis represents the rate of refractive index change (RIU / min). The figure contains two data curves: the solid line represents the change of precursor concentration (mg / L) over time, and the dashed line represents the change of refractive index change rate (R (RIU / min)) over time. It can be observed from the figure that as the reaction proceeds, both the precursor concentration and the rate of refractive index change (R) show a synchronous decreasing trend, indicating that the monitored physical property change rate... It can effectively characterize the consumption process of reactants; such as Figure 3 As shown, the platform acquires information from external data sources such as sensor input data. The data enters N parallel dedicated analysis channels to generate attention demand scalars. It then passes through a logic persistence verification module to filter out transient noise artifacts, and a contextual builder to aggregate rigid constraint demand trends. The processed information is sent to a rule-based attention arbitration module, which loads dedicated arbitration rule parameters from the knowledge base to perform core contextual reasoning and decision-making. The platform's analysis results are ultimately directed to a root cause insight module to analyze temporal correlations, and an arbitration pattern analysis module to calculate the health of logical operation. The analysis results are then used to form attention focus symbols and output to the decision support interface on the user terminal.

[0038] Example 4: In industrial production, to ensure that the nano-titanium dioxide adsorbent material prepared using the process of this invention meets the specific application requirements for specific applications, such as treating dye wastewater or heavy metal ion wastewater, and that its adsorption performance and batch stability meet the specific application requirements, it is necessary to calibrate two key parameter sets in the process flow: one is the first preset rate threshold used for closed-loop control ( ) and the second preset rate threshold ( Secondly, it determines the type and concentration of volatile catalysts that influence the microstructure and crystal phase of the product. This embodiment provides a calibration procedure for determining these parameters, performed in a 500L stainless steel reactor equipped with an online refractive index meter, with a measurement accuracy of [insert accuracy here]. Standard material batches were used, including diatomaceous earth pretreated in step 801, toluene solvent, and tetrabutyl titanate; the calibrated materials used to determine the termination of the grafting reaction in step 102 were calibrated. Initiate the calibration sample group to execute steps 101 and 102, at 50 The stirring control system calculates the first rate of change in real time. In addition, a timed sampling program was set up to extract a small amount of sample from the suspension every 15 minutes. After rapid centrifugation, only the supernatant was collected, and the concentration of residual titanium alkoxide precursor in the supernatant was determined using a conventional chemical analysis method, specifically ultraviolet-visible spectrophotometry. The curves showing the change of the value over time were plotted and compared with the curves showing the change of the precursor concentration in the supernatant over time. To further prove that the change in physical properties is due to the accumulation of alcohol byproducts, the present invention provides the measured data of the corresponding relationship shown in Table 2. The data were obtained by adding the byproduct (butanol) in a gradient to the standard reaction system and recording the sensor readings in real time.

[0039] Table 2: Relationship between cumulative concentration of by-products and physical properties (refractive index / viscosity)

[0040] By-product butanol volume concentration (%) System refractive index (RIU, 50°C) System viscosity (mPa-s, 50°C) 0.0 (pure solvent reference) 1.4962 0.520 0.5 1.4951 0.535 1.0 1.4940 0.551 2.0 1.4918 0.582 5.0 1.4852 0.675

[0041] As shown in Table 2, with the accumulation of byproduct concentration, the refractive index decreases linearly, while the viscosity increases steadily. This monotonic and unique correlation provides a basis for subsequent calculations of the rate of change. The determination of the saturation point of the reaction kinetics provides a solid physicochemical basis; data shows that the precursor concentration in the supernatant first drops below the detection limit 135 minutes after the start of the reaction, indicating that the grafting reaction on the carrier surface is basically complete at this point. However, reviewing the control system records reveals that within the time window of 135 to 150 minutes... The value stabilizes at to Within the range; select the median of this stable interval. And apply a safety factor of 0.8 to The calibration value is determined as Using a similar procedure, the accumulation rate of the byproduct (butanol) during the hydrolysis stage, i.e., step 103, is monitored and compared with the total amount of butanol that should be released after the theoretical molar amount of water vapor introduced has completely reacted. When the accumulation rate is lower than a preset threshold, indicating that the reaction is approaching its endpoint, the result can be similarly determined. ; The calibration is used to determine the termination of the grafting reaction in step 102. By comparing the precursor concentration change curves in the supernatant with... The curve of the value changing over time was determined by this invention. The stable range of the value; the method established in this invention for determining the reaction endpoint based on the rate of change R monitored by online physical sensors is based on a rigorous quantitative linear mapping logic: since the volume fraction of the byproduct alcohol in non-alcoholic organic solvents exhibits a strictly linear monotonic response relationship with the refractive index or viscosity of the suspension in the low concentration range, and their linear correlation coefficients are all greater than 0.998, the rate of change R of physical properties captured by the online physical sensor is essentially a precise mapping of the instantaneous rate of the chemical reaction. For reaction equipment of different scales or models, the determination of the first preset rate threshold and the second preset rate threshold follows the standard The standardized calibration procedure involves: first, determining the slope of the physical property response under a specific system; then, simultaneously monitoring the precursor conversion rate or water vapor consumption within the system using offline chemical analysis methods to identify the kinetic inflection point where the chemical reaction enters a plateau phase; finally, setting the rate of change of physical properties corresponding to this kinetic saturation point as the control threshold. This mechanism of offline pre-calibration driving online closed-loop control achieves precise quantitative control of the two chemical processes: heterografting and in-situ hydrolysis. Specifically, within a time window of 135 to 150 minutes, the median of the stable interval is selected, and a safety factor of 0.8 is applied. The calibration value is preferably determined as follows: (Taking an online refractive index meter as an example); Similarly, by monitoring the accumulation rate of byproducts during the hydrolysis stage and comparing it with the theoretical alcohol yield, The calibrated values ​​are specific values ​​that meet the criteria for the reaction endpoint. This quantitative threshold setting provides a specific process benchmark for automated closed-loop switching in large-scale production.

[0042] After determining the above control thresholds, the catalyst calibration procedure was further executed to meet the requirements of different adsorption applications for the microstructure of TiO2. Three parallel experimental groups were set up, namely experimental groups 4-A, 4-B, and 4-C, all of which adopted the process of this invention, including steps 801, 101, and 102, and used the calibrated catalyst. and As a control parameter; the only difference between the three experimental groups was the constant temperature bath (40°C) used in step 103. The solution components were as follows: experimental group 4-A used pure water; experimental group 4-B used a 1% v / v aqueous solution of acetic acid; and experimental group 4-C used a 1% v / v ammonia solution. After the reaction, the structures of the dried products (4-A, 4-B, and 4-C) were confirmed using recognized characterization methods in the art. X-ray diffraction (XRD) analysis showed that the TiO2 crystal phase of products 4-A (pure water) and 4-C (ammonia solution, alkaline) was mainly anatase, while rutile phase was detected in product 4-B (acetic acid, acidic). Nitrogen adsorption-desorption (BET) tests showed that product 4-C (ammonia solution) had the largest specific surface area, measured to be 185.2. The product 4-B (acetic acid) had the smallest specific surface area, measured at 95.7. This calibration procedure establishes a correspondence between catalyst type and product microstructure, enabling subsequent production to be targeted according to specific adsorption tasks. For example, anatase phase 4-C can be used for photocatalytic degradation of dyes, while rutile phase 4-B can be used for adsorption of specific ions.

[0043] Example 5: When the process of the present invention is applied to reactors of different sizes or when the type of online physical sensor is changed, in order to ensure the stability of process control, an engineering calibration procedure needs to be performed to determine the first preset rate threshold. With the second preset rate threshold This embodiment discloses a calibration method. The procedure, during the hydrolysis reaction in step 103, involves activating an online physical sensor (using an online refractive index meter as an example) to monitor the second rate of change. In addition, a high-precision dew point measurement system is installed at the gas phase outlet of the reactor containing water vapor. By real-time monitoring and integration calculation of the water vapor partial pressure difference and gas flow rate between the reactor inlet and outlet gases, the instantaneous rate and cumulative molar amount of water vapor consumed by the reaction system can be obtained. When the monitored cumulative molar amount of water vapor consumed reaches the preset value of the stoichiometric moles theoretically required for complete hydrolysis of the titanium alkoxide precursor fed in step 101, which can be 99.5%, the hydrolysis reaction is determined to be terminated, and the second rate of change measured by the online refractometer at this moment, indicating that it has entered a stable plateau, is recorded. The value, which is specified for use with that particular system. .

[0044] In another embodiment, if the online physical sensor selected by the process system is an online viscometer for monitoring changes in the viscosity of the suspension, its corresponding... and The calibration procedure is as follows: Perform calibration according to a procedure similar to that in Example 4. During the grafting reaction in step 102, the concentration of the precursor in the supernatant was monitored by timed chemical analysis to determine the actual endpoint of the grafting reaction. The first rate of change at which the reaction had reached a stable plateau, as measured by an online viscometer, was recorded at this point. The value is calibrated to a first preset rate threshold for use in an online viscometer; the aforementioned steps of this embodiment are performed. The calibration procedure involves determining the actual endpoint of the hydrolysis reaction during step 103 using a high-precision dew point measurement system, and recording the second rate of change measured by the online viscometer at this point, indicating that the reaction has reached a stable plateau. The value is calibrated as a second preset rate threshold for use in online viscometers. Through the above procedure, it is ensured that regardless of the type of physical sensor used, whether it is a refractometer or a viscometer, the process control system can determine and automatically switch the endpoints of the two-stage reaction based on the calibrated threshold.

[0045] Example 6: In industrial-scale production, to address raw material batch fluctuations and suppress solvent escape during the process, ensuring process stability and economy, the process of this invention can be further enhanced with standardized pretreatment procedures. In specific process deployment, to eliminate interference from the non-alcoholic organic solvent (toluene in this example) used in step 101 and trace amounts of moisture that may be adsorbed during storage or transportation of the dried diatomaceous earth carrier in subsequent step 102 (without liquid water grafting), an azeotropic pre-drying step can be performed after step 101 or simultaneously with the carrier dispersion in step 101. In this step, the suspension (before the addition of the titanium alkoxide precursor) is heated in the reactor to the boiling point of the solvent (toluene) and maintained under reflux or slight distillation for a period of time. The trace amounts of water present in the system are removed by distillation using the lowest azeotrope formed by toluene and water until the system is confirmed to be anhydrous through online monitoring (e.g., water content detection at the condenser). The suspension is then cooled to the reaction temperature required for step 102, such as 50°C. Then, titanium alkoxide precursor is added to initiate the grafting reaction.

[0046] To address the potential loss of toluene, a non-alcoholic organic solvent, during prolonged operation (e.g., 6-8 hours) of the gas-phase rate-controlled hydrolysis in step 103, the apparatus for preparing the gas containing water vapor can be improved. In this embodiment, the dry carrier gas, such as N2, is passed in series through at least two constant-temperature baths before entering the reactor. The carrier gas passes through a first constant-temperature bath containing toluene, a solvent of the same type as the non-alcoholic organic solvent. The temperature of this first constant-temperature bath is controlled to be equal to or close to the reaction temperature of the suspension in step 103, such as 50°C. This process pre-saturates the carrier gas with solvent vapor; the carrier gas, now saturated with solvent vapor, then passes through a second isothermal bath containing water, the temperature of which is controlled at a specific temperature, such as 40°C. The partial pressure of water vapor is adjusted; finally, this mixed gas containing both saturated solvent vapor and controlled water vapor is introduced into the suspension. This procedure suppresses the net evaporation of solvent in the reactor and ensures the stability of the concentration of the reaction system without affecting the controlled supply of water vapor.

[0047] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A process for the preparation of nano-titania adsorbent material by sol-gel method, characterized in that, The process comprises the following steps: Step 101, dispersing the dried diatomite carrier in a non-alcohol organic solvent containing a titanium alkoxide precursor to form a suspension; Step 102, maintaining the suspension to perform a grafting reaction releasing alcohol by-products without adding liquid water, while monitoring in real time a physical property characterizing the accumulation concentration of the alcohol by-products by an online physical sensor, and determining a first change rate based on the physical property; Step 103, when the first change rate is lower than a first preset rate threshold, determining that the grafting reaction is terminated, and starting to introduce a gas containing water vapor into the suspension to perform a hydrolysis reaction releasing alcohol by-products, while continuously monitoring the physical property by the online physical sensor, and determining a second change rate based on the physical property; Step 104, when the second change rate is lower than a second preset rate threshold, determining that the hydrolysis reaction is terminated, and starting a separation and drying step to obtain a nano-titanium dioxide adsorption material.

2. The process for preparing nano-titania adsorbent material by sol-gel method as claimed in claim 1 wherein, The gas containing water vapor in step 103 also contains volatile catalyst vapor, and the preparation step of the gas comprises: passing a carrier gas through a constant temperature bath containing an aqueous solution of the volatile catalyst.

3. The process for preparing nano-titania adsorbent material by sol-gel method as claimed in claim 1 wherein, The physical property is the refractive index of the suspension, and the online physical sensor is an online refractometer.

4. The process for preparing nano-titania adsorbent material by sol-gel method as claimed in claim 1 wherein, The physical property is the viscosity of the suspension, and the online physical sensor is an online viscometer.

5. The process for preparing nano-titania adsorbent material by sol-gel method as claimed in claim 2 wherein, The aqueous solution of the volatile catalyst is an aqueous acetic acid solution.

6. The process for preparing nano-titania adsorbent material by sol-gel method as claimed in claim 2 wherein, The aqueous solution of the volatile catalyst is aqueous ammonia.

7. The process for preparing nano-titania adsorbent material by sol-gel method as claimed in claim 1 wherein, The first change rate and the second change rate are determined according to calculated, wherein, is the first change rate or the second change rate, is a preset time window, is a current time measurement value of the physical property, is a previous time measurement value of the physical property, and a time interval between the current time measurement value and the previous time measurement value is .

8. The process for preparing nano-titania adsorbent material by sol-gel method as claimed in claim 1 wherein, The process further comprises, before step 101, a step 801 of pretreating the dried diatomite carrier with a silane coupling agent to construct functional functional groups on the surface of the dried diatomite carrier; and the dried diatomite carrier in step 101 is the dried diatomite carrier pretreated by step 801.

9. The process for preparing nano-titania adsorbent material by sol-gel method as claimed in claim 1 wherein, The non-alcohol organic solvent is an alkane solvent.

10. The process for preparing nano-titania adsorbent material by sol-gel method as claimed in claim 1 wherein, The non-alcohol organic solvent is an aromatic hydrocarbon solvent.

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