可降解微塑料PLA与PBS对Cd2+的吸附性能与机制OA

Since the implementation of the"Plastic Restriction Order",the environmental behavior of biodegradable plastics in adsorbing heavy metals to form composite pollutants has attracted significant attention.However,their interfacial interaction mechanisms and migration risks remain unclear.This study investigated the adsorption behavior and mechanisms of cadmium ions(Cd2+)using biodegradable plastics—polybutylene succinate(PBS)and polylactic acid(PLA)—as models.The results indicated that the adsorption of Cd2+by these two types of biodegradable microplastics followed pseudo-second-order kinetics and the Freundlich model,suggesting that the adsorption process involves both physical and chemical interactions.The saturated adsorption capacity of PBS reached 1.13 mg·g-1,which is 22.8％higher than that of PLA(0.92 mg·g-1).Thermodynamic analysis revealed negative ΔG values,indicating a spontaneous adsorption process,while ΔS>0 suggested that physical adsorption(electrostatic interaction)played a dominant role.By comparing changes in surface functional groups of the microplastics before and after adsorption,the primary adsorption mechanisms were confirmed to be electrostatic interactions and metal ion coordination complexation,accompanied by van der Waals forces.This study provides valuable data for assessing the environmental fate of biodegradable microplastics and the risks associated with composite pollution.