Characteristics Of Sorption And Desorption Of Phthalate Acid Asters On Suspended Particulate Matter

Behaviors of sorption and desorption of organic pollutants on suspended particulate matter (SPM) play an important role in their transport, transformation and bioavailability in natural environment, and are influenced by factors such as physical-chemical properties of organic pollutants, composition of sorbent, evironmental condition and coexistent organic compounds. Presently, knowledge of mechanism of sorption and desorption is limited, which results in significant errors in environmental prediction of fate of organic compounds in aqueous environment.Behaviors of sorption, desorption and hysteresis of dibutyl phthalate (DBP) and Di-(2-ethyl)hexyl phthalate (DEHP) on three kinds of SPM, including suspended sediment particulate, Chlorella vulgari and Microcystis aeruginosa, were studied. Effects of environmental factors on sorption of DBP and DEHP were investigated. Field sampling was also proceeded.Experimental results are as follows:(â…°) Sorption equilibrium of DBP and DEHP on the SPM was reached quickly, 2 h for suspended sediment and 0.5 h for phytoplankton.(â…±) Sorption ability of DEHP on SPM was significantly higher than that of DBP. Sorption ability between the SPM for DBP or DEHP differed greatly. Sorption ability of DBP and DEHP in humic materials was higher that that in algal organic matter. Fat was approved to have played an important role in the process of sorption.(â…²) All kinds of SPM were found to exhibit significant sorption-desorption hystersis phenomenin, and the extent of hystersis for suspended particulate was obviously larger than phytoplankton, and the extent of hystersis for DBP was larger than DEHP.(â…³) The sorption amounts of DBP and DEHP increased with the increase of humic acid concentration, temperature, pH and salinity, while decreased with increasing SPM concentration.(â…´) Field investigations in Bohai estuary, Haihe river and a small lake showed that DBP and DEHP were found in all the samples of water and sediment, and enriched in sediment. Distribution of DBP and DEHP between water and sediment was nearly reached equilibrium in Haihe river and the small lake, and far away from equilibrium in Bohai estuary. Sediment was the sink of DBP and DEHP.