Phenol is the main pollutant in wastewater, especially in plastic production and pesticide use.
Phenol is very destructive to organisms. When phenol wastewater is discharged, an activated carbon fixed-bed should be used for dynamic adsorption. After removing phenol substances in wastewater, the wastewater can be safely discharged, reducing the pollution of wastewater to the environment and protecting the natural environment.
Adsorption and purification analysis of activated carbon fixed bed for phenol wastewater
Phenol wastewater is more harmful and is commonly found in chemical plants, pharmaceutical plants, plastic plants and other industries. Phenol is the main pollutant in phenolic substances, and its impact on the natural environment cannot be ignored.
Phenol can easily lead to biological failure and even death in severe cases.
Activated carbon fixed bed has the function of adsorption and purification on phenol wastewater, which solves the harm of phenol wastewater. Activated carbon adsorption is an important method in the purification of phenol wastewater. The activated carbon fixed bed is used to improve the purification level of phenol wastewater. It is an effective method for dynamic adsorption of phenol wastewater, and it has reached mature technological standards.
The activated carbon fixed-bed purifies various pollutants in the phenol wastewater by dynamic adsorption, ensuring that the phenol wastewater can meet the discharge standard, and at the same time, it is beneficial to improve the recovery and utilization of the phenol wastewater.
Dynamic adsorption test of activated carbon fixed bed in phenol wastewater
(1) Test preparation.
The activated carbon was prepared in the test, and the specific surface area of the activated carbon was required to be 998.4 m2/g, the methylene blue was 279 mg/g, and the iodine value was 788 mg/g. Phenol. In this experiment, ultrapure water and phenol are specially used to fuse to prepare a phenol solution.
In the experiment of dynamic adsorption of activated carbon fixed bed, a constant flow pump needs to be prepared. The constant flow pump of the model HL-2B can be selected. The adsorption column made of glass material is used in the dynamic adsorption.
(2) Test process.
The basic structure of the test is: in a normal room temperature environment, first place the cotton mesh on the lower part of the glass adsorption column, and try to choose a cotton mesh with a large aperture; then, fix the phenol adsorption column to the iron shelf, and put an appropriate amount into the adsorption column. At the same time, connect the bottom of the adsorption column to the constant flow pump, and use a rubber tube to connect the two.
Phenol water will flow in a bottom-up sequence under siphon conditions. In the experiment, in order to simulate the dynamic adsorption conditions of the activated carbon fixed bed, the rate of phenol solution needs to be adjusted. According to the dynamic adsorption conditions of activated carbon fixed-bed for phenol wastewater, the content of the research and experiment was designed.
According to the actual situation of phenol wastewater, a phenol solution was prepared to replace phenol wastewater. The content of phenol in the water was detected in the test. On this basis, the correlation curve of dynamic adsorption was drawn. The raw water was used as a reference, and the marked phenol content was 10% and 90%. adsorption time.
In the test, the initial influent flow, phenol content, and simulated height of the activated carbon fixed-bed were measured, and the effects of three parameters on dynamic adsorption were studied.
The initial influent flow is 4.82mL/min, and the value of the fixed bed height is 12cm at this time. In the experimental study, the phenol solution is configured with 3 mass concentrations: 100mg/L, 150mg/L, 200mg/L, which are used for research The fixed bed height of the influent flow at different mass concentrations of phenol solution.
In the test, the mass concentration of the phenol solution was set to 150 mg/L, the height of the fixed bed was set to 12 cm, and the two parameters were kept unchanged. When measuring the height data of the fixed bed, record the mass concentration of the phenol solution and the volume flow of the influent water.
In the test, the specified measurement method was used to analyze the effect of activated carbon fixed bed on the dynamic adsorption of phenol wastewater.
According to the experimental research process, a mathematical model for studying dynamic adsorption is constructed. The model must match the experiment. The mathematical model simulates the process of the experiment, and is committed to obtaining the experimental data of the dynamic adsorption of phenol wastewater on the activated carbon fixed bed.
In the above formula, ρ0 and ρ represent the mass concentration of the initial influent water and the mass concentration of phenol in the effluent; kYN is the adsorption rate constant, and t and t0.5 represent the adsorption time and the time consumed when the mass concentration of the effluent reaches 50% of the phenol in the influent water. [4].
The mathematical calculations in this breakthrough model specifically analyze the adsorption mass transfer rate, and the model shows that the larger the adsorption constant, the greater the slope of the curve of the breakthrough model.
In the experiment, the theory of invalid thickness was also studied. The invalid thickness refers to the dynamic adsorption at the point of penetration during the dynamic adsorption of phenol wastewater by the activated carbon fixed bed. The capacity state of complete adsorption does not actually fully adsorb the matching phenol mass concentration. The expression formula of the invalid thickness theory (LUB) is as follows:
In the formula, L is the length of the fixed bed, tb is the breakthrough time, and t* is the operating time at 0.5 o’clock.
Dynamic adsorption results of activated carbon fixed-bed in phenol wastewater
According to the dynamic adsorption research of activated carbon fixed-bed in phenol wastewater, the influence results of dynamic adsorption are analyzed from three aspects: phenol content in influent, height of fixed bed, and influent flow rate, as follows:
3.1 Influent phenol
Figure 1 below is for reference, and the results of dynamic adsorption of activated carbon fixed bed in the influent phenol are analyzed. In the initial stage, when the content of influent water increases, the curve of breakthrough time has an obvious left-shift phenomenon.
That is to say, the content of phenol will have a certain influence on the saturation rate of the activated carbon fixed bed. As the content of the phenol solution increases, the driving force of the dynamic adsorption of the fixed bed will also increase, and the activated carbon adsorbs a large number of phenol substances. The mass of the phenolic substance increases, driving the speed of the forward drive.
3.2 Fixed bed height
When the height of the fixed bed increases, the contact time between the phenol in the wastewater and the activated carbon will become longer, which increases the amount of phenol dynamically adsorbed by the activated carbon, and the penetration point will move to the right. The residence time in the bed will increase, which will promote the dynamic adsorption of phenol by activated carbon, effectively improve the adsorption capacity of the fixed bed, and ensure the effect of dynamic adsorption.
3.3 Influent flow
After the influent flow of the phenol, wastewater solution is accelerated, the penetration point is shifted to the left, indicating that the larger the influent flow rate is, the shorter the contact time between the phenolic substances in the wastewater and the activated carbon fixed bed, and the fixed bed will tend to be saturated in a short time. the time of penetration. The effect of dynamic adsorption on activated carbon fixed-bed at a high flow rate is not as good as that under low flow rate conditions.
To sum up, when activated carbon fixed-bed dynamically adsorbs phenol in wastewater, it is affected by the factors of influent flow, fixed bed height, and influent flow. Only by adjusting various parameters can the dynamic adsorption effect of activated carbon fixed-bed be ensured and the phenol wastewater is purified.
4 Conclusion
The dynamic adsorption of activated carbon fixed-bed in phenol wastewater purifies wastewater resources and solves the environmental pollution problem of phenol wastewater.
The dynamic adsorption method of the activated carbon fixed-bed determines the purification effect of the phenol wastewater. The specific application of the activated carbon fixed-bed is planned by the method of experimental research to meet the purification requirements of the phenol wastewater. The most important thing is to optimize the activated carbon fixed bed in the phenol wastewater. dynamic adsorption.