Desorption And Biodegradation Of Black-Carbon-Sorbed Phenol During Aging

At present, more and more researches focused on aging effect (sorption contact time) to organic compounds sorbed to natural organic matter in environmental science. Many informations presented that the desorption hysteresis become obviously compared aged contaminants in soils to freshly added compounds, and the bioavailability of organic compounds in soils declines with sorption contact time. However, most of laboratory experiments and pollutants risks are based on short term tests. Black carbon, a super-sorbents widely existed in soils, is totally significant in aging effects. Early testes focus on short-term bioavailability of sorbed organic pollutants in soils, but there is rarely systematical research on the long term aging to sorption/desorption and biodegradation of contaminants in black carbon.Aging was emphasized to study the desorption and biodegradation of phenol in black carbon. Black carbon (BCs) derived from Pinus massoniana Lamb residues were used as sorbents. Sorption isotherms assays were set to calculate the distribution coefficients (KF), while the desorption kinetic experiments were to figure up desorption rate parameters using three-site desorption model. Series dilution desorption experiences were set to measure the factor of non-desorbable phenol(fnd) in black carbon in ten days. Biodegradation assays were used to investigate phenol-degrading behavior under two bacterial densities of Pseudomonas putida. The result shows that phenol sorption isotherms are well evaluated by Freundlich sorption isotherms (n ranges from0.413to0.261, R2ranges from0.988to0.993) during aging period ranged from1day to22days. KF values are strongly correlated to chemical-BCs contact time increasing6496.7to19555.8(mg-kg-1)mg·L-1)-n. One thing to be noted that fnd values stay a high level and increase60.4%to85.7%as prolonged time which is attributed to abundant surface areas and ample micro pore area (117.7m2·g-1). For all aged BCs, the sorbed phenol in readily desorption sites shifts into resistant desorption sites during aging. Reduced biodegradation of sorbed chemical is observed during aging. But there is no obviously statistics biodegradation difference between two studied bacterial densities. Another noteworthy result in our study is some part of sorbed phenol in non-desorbable site could be biodegraded.