Treatment Methods for P-Nitrobenzoic Acid Wastewater

Nitrobenzoic acid, used in the synthesis of industrial dyes, poses a significant threat to the environment and atmosphere once discharged into natural ecosystems. It can cause severe pollution to water bodies and the atmosphere. Furthermore, it exerts irritant effects on the eyes, skin, mucous membranes, and upper respiratory tract of humans and animals. The stable structure of P-nitrobenzoic acid. makes it challenging to remove through conventional processes. Therefore, effective management of P-nitrobenzoic acid in water bodies is crucial for improving the ecological environment and safeguarding the health of both humans and animals

At present, scholars both domestically and internationally have explored various primary treatment methods for wastewater containing P-nitrobenzoic acid. These methods include adsorption, photocatalysis, ultrasonic oxidation, electrochemical treatment, chlorine dioxide catalytic oxidation, ozone oxidation, as well as combined processes and anaerobic-aerobic biological methods. Among them:"

①Adsorption method belongs to physical treatment technology.

Advantages: Simple operation, fast reaction.

Disadvantages: High material costs and potential for secondary pollution.

One of the methods involves using resin for adsorption, followed by passing the adsorbed liquid into a concentration device for concentration at a temperature of 70 to 95°C. This process yields nitric acid recovery liquid and condensate. Regenerating agent is introduced into a container containing the resin after adsorption for regeneration, resulting in a regeneration liquid. The regeneration liquid is subjected to distillation, producing distilled components and bottom liquid. This method significantly achieves the resource utilization of by-products, accomplishes "zero emissions," and consequently reduces the cost of wastewater treatment.

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② Photocatalysis, Ultrasonic Oxidation, Electrochemical Method, Chlorine Dioxide Catalytic Oxidation, Ozone Oxidation, and their Combination Processes belong to chemical treatment technology.

Advantages: Rapid reaction rates, high tolerance to pollutant concentrations.

Disadvantages: Large equipment investment, excessively high operational costs.

③ Anaerobic-Aerobic Biological Method belongs to biological treatment technology.

Advantages: Easy to operate and manage, low construction and maintenance costs, does not cause secondary pollution.

Disadvantages: High toxicity to wastewater containing P-nitrobenzoic acid., strong toxic effects on microorganisms, difficulty in selecting and cultivating specific bacterial strains, and excessively slow treatment efficiency.

④ Sulfuric Acid Oxidation Method belongs to chemical treatment techniques.

Utilizing industrial waste sulfuric acid, employing a waste treatment approach. The primary sources of waste sulfuric acid include titanium dioxide waste sulfuric acid, aromatic hydrocarbon nitration waste sulfuric acid, dye waste sulfuric acid, etc., treated through a concentration process. During the concentration process, organic impurities undergo oxidation, polymerization, and other reactions, transforming into dark-colored gelatinous or flocculent substances. With the further increase in temperature, these substances are converted into oxides of carbon, water, and nitrogen. The sulfuric acid treated through concentration can be recycled for reuse.

⑤ Evaporation and Biochemical Method.

Disadvantages: Prone to tar formation, poor equipment stability, difficulty in resolving biochemical total nitrogen issues, and a large footprint for biochemical processes.

⑥ Deep Oxidation and Evaporation Method.

Disadvantages: High equipment requirements, elevated operating costs, significant impact on treatment efficiency due to fluctuations in different batches of wastewater.

⑦Incineration Method.  

Disadvantages: The need for post-incineration flue gas treatment, resulting in high costs.