Biodegradation of poly(aspartic acid-lysine) copolymers by mixed bacteria from natural water

Poly(aspartic acid-lysine) copolymers (PAL), as an alternative product to traditional water treatment agents, was developed based on poly(aspartic acid) through microwave-assisted synthesis of aspartic acid and lysine. Its biocompatibility and performance in inhibiting scale and corrosion are determining factors in its application. In this paper, biodegradability of PAL was investigated by carbon dioxide evolution tests. The degradation ratio of PAL on day 10 and day 28 respectively reached 35.01% and 80.00%, which indicated that PAL was a degradable water treatment agent. PAL is superior to polyacrylic acid and phosphonic carboxylic acid in biodegradability. With the increase in the addition ratio of lysine in copolymerization process and the decrease in the molecular weight of copolymer, the biodegradability of PAL was significantly enhanced. In addition, the incubation period before the biodegradation was shortened. The result showed that Cu2+ could decrease the degradation rate through inhibiting enzymatic activities.