Laboratory waste liquid of toluene in activated carbon adsorption recovery process

With the increasing demand for laboratory waste liquid treatment, how to efficiently recover toluene in waste liquid has become an important topic in the field of chemistry and chemical engineering. Activated carbon is a kind of commonly used adsorption material, because of its high specific surface area, porous structure and good adsorption performance, is widely used in the recovery of toluene in laboratory waste liquid. In this paper, the activated carbon adsorption recovery process of toluene in laboratory waste liquid will be discussed in detail, and its principle, steps and advantages and disadvantages will be analyzed.

1. activated carbon adsorption recovery of the basic principles

Activated carbon is a kind of porous carbon material with high specific surface area and rich microporous structure. These properties make it possible to capture volatile organic compounds (such as toluene) by physical or chemical adsorption. Toluene is a common organic solvent, which often contains a high concentration of toluene in laboratory waste liquid, which can be effectively separated from waste liquid by activated carbon adsorption.

The principle of activated carbon adsorption is mainly based on intermolecular forces, including van der Waals and hydrogen bonding. The adsorption process of toluene molecules on the surface of activated carbon is divided into two stages: toluene molecules enter the microporous structure of activated carbon through molecular diffusion; toluene molecules interact with the pore wall on the surface of activated carbon and are fixed on its surface. This adsorption process has the characteristics of high efficiency and environmental protection, and is an ideal recovery method.

2. activated carbon adsorption recovery process steps

The activated carbon adsorption recovery process of toluene in laboratory waste liquid mainly includes the following steps:

1. Waste liquid pretreatment

Before the adsorption process, the waste liquid needs to be pre-treated. The purpose of pretreatment is to remove solid impurities, suspended solids or other substances that may affect the adsorption efficiency of activated carbon in the waste liquid. Specific operations include filtration, precipitation or distillation to ensure the purity of the waste liquid.

2. Adsorption process

The pre-treated waste liquid was passed through an activated carbon adsorption column, and the toluene molecules were captured and enriched by the activated carbon. In the adsorption process, the selectivity and adsorption capacity of activated carbon are the key factors. The adsorption efficiency of toluene can be significantly improved by selecting activated carbon with appropriate pore size and specific surface area.

3. Desorption and regeneration

The activated carbon after adsorption saturation needs to be desorbed to restore its adsorption performance. Common desorption methods include thermal desorption and solvent desorption. Thermal desorption is to volatilize toluene molecules on the surface of activated carbon by heating, while solvent desorption is to elute toluene from activated carbon by using a specific solvent. The toluene gas or liquid after desorption can be recycled, while the activated carbon needs to be regenerated.

4. Regeneration process

The regeneration of activated carbon is to restore its adsorption performance and extend its service life. Common regeneration methods include high temperature roasting, chemical oxidation and catalytic reduction. High-temperature roasting is the most commonly used regeneration method. The toluene molecules adsorbed on the surface of activated carbon are decomposed by high temperature to restore it to its original state.

3. activated carbon adsorption recovery of the advantages and disadvantages

Advantages

1. Efficient adsorption: activated carbon has a high specific surface area, can quickly adsorb waste liquid in the toluene molecules, the adsorption efficiency of up to 90%.
2. Economy: Compared to other recovery methods (such as distillation or extraction), activated carbon adsorption cost is low, and the operation is simple.
3. Environmental: activated carbon adsorption is a physical process, will not produce secondary pollution, in line with environmental requirements.

Disadvantages

1. Activated carbon loss: activated carbon in the adsorption and regeneration process will be subject to a certain degree of wear, affecting its long-term use effect.
2. Adsorption capacity is limited: the adsorption capacity of activated carbon is limited by pore structure and surface chemical properties, for high concentration of toluene waste liquid may need multiple adsorption to achieve the desired effect.
3. Regeneration energy consumption is high: the regeneration process of activated carbon requires higher energy input (such as high temperature roasting), which increases the operating cost of the process.

4. activated carbon adsorption recovery application prospect

Activated carbon adsorption recovery process has broad application prospects in the treatment of laboratory waste liquid. This method can efficiently recover toluene and reduce the pollution of laboratory waste liquid to the environment; the recovered toluene can be reused in experiments or production, reducing the cost of experiments; the activated carbon adsorption process is simple, easy to operate, and suitable for waste liquid treatment in small and medium-sized laboratories.

With the increasingly stringent environmental regulations and the increasing demand for laboratory waste liquid treatment, activated carbon adsorption recovery process will be more widely used. In the future, by optimizing the structure and performance of activated carbon and developing new adsorption materials, the activated carbon adsorption recovery process will be more efficient and economical.

5. Conclusion

The activated carbon adsorption recovery process of toluene in laboratory waste liquid is an efficient and environmentally friendly treatment method. Through reasonable process design and optimization, the recovery rate of toluene can be significantly improved, and the environmental pollution of laboratory waste liquid can be reduced. The activated carbon adsorption process also has some limitations, such as activated carbon loss and high regeneration energy consumption, which need further research and improvement.

Activated carbon adsorption recovery process has important application value in the field of laboratory waste liquid treatment, which is worthy of further promotion and research.