Degradation of 2,4-dichlorophenoxyacetate isopropyl amine (2,4-D IPA) by O₃/AC/UV in an internally slurry airlift photo-reactor

ABSTRACT

An externally illuminated slurry airlift reactor (ALR) was used to decompose 2,4-dichlorophenoxyacetate isopropyl amine during catalytic ozonation with activated carbon. The effect of superficial gas velocity (0.05–0.15 cm/s), UV_AB irradiation (0–60 W), treatment period (10–30 min) and amount of activated carbon (0–0.8 g/l) on removal efficiency was investigated using response surface methodology (RSM) based on the Box–Behnken surface statistical design. Well-defined circulation pattern in the ALR allowed all the fluid elements to be exposed to high light intensity zone and achieve sufficient contact between the solid catalyst and the pollutant. Treatment period appeared as the most influential variable followed by the amount of activated carbon, superficial gas velocity and UV irradiation. A kinetic study was also carried out to evaluate the degradation efficiency versus the O₃, O₃/AC, O₃/UV and O₃/AC/UV combinations in which the last one had the highest impact. Efficient suspensions of AC in the ALR resulted in the high efficiency of the O₃/AC system. No significant difference was observed between the overall kinetic constants determined in O₃/AC and O₃/AC/UV systems due to the light transmission obstacle of solid suspension.

KEYWORDS:

• Airlift reactor
• activated carbon
• ozone
• ultraviolet irradiation
• 2,4-dichlorophenoxyacetate isopropyl amine (2,4-D IPA)

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Negin Farhadian http://orcid.org/0000-0001-5748-5406

Jamshid Behin http://orcid.org/0000-0002-6556-8743