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Table 1

Characteristics of physical modification

Methods	Mechanism	Pollutants	Advantages	Disadvantages	Reference
Muffle furnace-heating	Water evaporation and smoothing the channel and hole	Ammonia	Simple and convenient	Power-wasting; inefficient	Ali et al. (2014)
Microwave oven-heating	Elimination of impurities from channel; increase hole diameter; uniform pore size	Ammonia	Heating time saving; good penetration; high efficiency	Uneven heating because of moisture in the zeolite	Gracia et al. (2013), Bagheri et al. (2015)
Ultrasonic	Elimination of impurities from channel; increase surface area	Ammonia	Good penetration; removal of impurities from channel	Inefficient; always combined with other methods	Zielinski et al. (2015)

Methods	Mechanism	Pollutants	Advantages	Disadvantages	Reference
Muffle furnace-heating	Water evaporation and smoothing the channel and hole	Ammonia	Simple and convenient	Power-wasting; inefficient	Ali et al. (2014)
Microwave oven-heating	Elimination of impurities from channel; increase hole diameter; uniform pore size	Ammonia	Heating time saving; good penetration; high efficiency	Uneven heating because of moisture in the zeolite	Gracia et al. (2013), Bagheri et al. (2015)
Ultrasonic	Elimination of impurities from channel; increase surface area	Ammonia	Good penetration; removal of impurities from channel	Inefficient; always combined with other methods	Zielinski et al. (2015)