2.2. Flotation equipment and test procedure
The flotation tests were conducted for about 6 min in a glass column with a height of 170 mm and a diameter of 30 mm. Air was passed through the sand core to produce gas bubbles, and the airflow rate was 6 ml min−1. At the end of the flotation test, theoverflowed and submerged plastic particles were collected, rinsed with tap water, dried in atmosphere, and weighed.