A method for treating wastewater containing low-concentration ammonium perfluorooctanoate using modified molecular sieve as a catalyst

Abstract

The invention discloses a method for treating wastewater containing low-concentration ammonium perfluorooctanoate by taking modified molecular sieves as a catalyst. The method comprises the following steps: preparation of the modified molecular sieves, namely preparing a mixed solution containing cerous nitrate, lead nitrate, manganous nitrate or ferric nitrate, dipping molecular sieves in the mixed solution, taking out the molecular sieves and then drying and roasting the molecular sieves; catalytic ozonation, namely pouring the obtained modified molecular sieves and wastewater which has the temperature of 20-100 DEG C and the ammonium perfluorooctanoate concentration of 50-500mg / L into a container, introducing ozone, and meanwhile, starting stirring for 30-120 minutes; recovery of the modified molecular sieves, namely standing, centrifuging or filtering the turbid solution obtained by virtue of catalytic ozonation, thereby separating out the modified molecular sieves from the solution for recycling in the next catalytic oxidization process. The method has the advantages of high treatment efficiency, simplicity and convenience in operation, no secondary pollution, low operation cost and the like.

Description

technical field [0001] The invention belongs to the field of water treatment and environmental catalysis, and relates to a method for using a modified molecular sieve as a catalyst to oxidize and degrade low-concentration perfluorooctanoic acid ammonium wastewater. Background technique [0002] With the wide application of organic fluorine compounds, ammonium perfluorooctanoate (PFOA), as an organic fluorine surfactant with excellent performance, is usually an indispensable processing aid for the production of high-efficiency fluoropolymers. These high-performance fluoropolymers can be widely used in aviation technology, transportation, electronics industry, and household products such as kitchen utensils. For example, when producing polytetrafluoroethylene resin by dispersion method, a certain amount of dispersant ammonium perfluorooctanoate should be added. Finally, the wastewater generated in these production processes contains low concentration of perfluorooctanoate ions...

AI Technical Summary

Problems solved by technology

For example, when producing polytetrafluoroethylene resin by dispersion method, a certain amount of dispersant ammonium perfluorooctanoate should be added. Finally, the wastewater generated in these production processes contains low concentration of perfluorooctanoate ions, usually only about 0.1%, or even lower, and the recovery value low, relatively difficult to handle

Ammonium perfluorooctanoate is an expensive and efficient surfactant with stable physical and chemical properties and is difficult to biodegrade. Ammonium perfluorooctanoate discharged with wastewater will be released in the environment after decomposition and accumulate in the human body, causing great harm to the human body

There are few studies on the treatment of low-concentration ammonium perfluorooctanoate wastewater at home and abroad, and traditional separation methods such as precipitation, vacuum distillation, anion exchange, etc. are mainly used. Since the concentration of ammonium perfluorooctanoate in wastewater is often very low, if it is used, it will be difficult to recycle and consume High energy, large equipment investment, and secondary pollution problems. If the perfluorooctanoic acid ammonium wastewater is directly treated, there are problems such as complex process, low recycling rate, and difficulty in industrialization.