Research has shown that the average biodegradation rate of the reference sample on the 14th day is 73.53%, and on the 28th day it is 73.56%. It exceeds the passing level of 60% rapid biodegradation within 14 days. At the end of the experiment, the difference between the two parallel degradation rates is less than 20%; The biodegradation rate of the toxicity control group on the 14th day was 48.45%, which exceeded the toxicity inhibition judgment level of 25% degradation rate within 14 days. This indicates that PFBSK has no inhibitory effect on microorganisms.

Meanwhile, the average biochemical oxygen demand of the blank control group was 42.65mg/L, which was less than 60mg/L. Within 28 days, the degradation rate of PFBSK is basically zero, and it does not have rapid biodegradability.

The average degradation rates of the reference sample on the 7th and 14th day of the experiment were 75.15% and 79.31%, respectively, which met the quality control requirements that the biodegradation rate of the reference sample should be higher than 40% after 7 days and higher than 65% after 14 days. This indicates that the activity of the inoculum in the degradation test system is normal.

The degradation rate of the toxicity control group on the 14th day was 56.15%, and PFBSK had no significant toxic inhibitory effect on the inoculum at the tested concentration.

The BOD measurement results showed that the cumulative oxygen consumption of the three parallel groups in the 28 day sample group was 111.0, 111.0, and 112.0 mg/L, respectively, which was close to the average cumulative oxygen consumption of the two parallel groups in the blank control group (112.0 mg/L). According to the calculation of biochemical oxygen consumption, the biodegradation rate of PFBSK did not undergo final biodegradation.

The results indicate that PFBSK and potassium perfluorooctane sulfonate (PFOSK) have certain similarities, both having high melting point, low vapor pressure, and significant persistence. But there are significant differences between the two in terms of water solubility and accumulation. At 20 ℃, the water solubility of PFBSK is 49.3g/L, which is highly soluble in water; The water solubility of PFOS is only 519mg/L. The accumulation factor (BCF) of PFBSK is 3.16, indicating no accumulation; The BCF of PFOS is 6531, and there is a significant biomagnification effect in the food chain.