老化对黑碳中吸附态苯酚的脱附及微生物降解的影响

采用松木基黑碳为吸附剂,考察了老化作用对吸附态苯酚的脱附及微生物降解作用的影响.苯酚吸附等温线数据采用非线性Freundlich方程拟合,脱附数据采用三位点脱附模型拟合,微生物降解试验分别在恶臭假单胞菌ATCC 11172的两种菌密度下进行.结果表明,平衡位点、非平衡位点以及不可脱附位点这三种位点在不同老化时间内都存在,其中不可脱附位点上的比例(fnd60.4%)都占绝大部分,并且随着老化时间增加,易脱附位点上的苯酚逐渐往不易脱附的位点转移;通过对连续稀释脱附数据的分析表明,脱附体系中脱附产物的不定期移除(非生物移除)能够极大地促进脱附的进行;老化时间越长,吸附态苯酚的生物可利用性越小,但同一老化时间内两组不同菌密度之间的生物可利用性并无明显的统计学差异;同时发现黑碳中不可脱附位点上的部分苯酚亦能被降解.

Desorption and biodegradation of black-carbon-sorbed phenol during aging

Using black carbon(BCs) derived from Pinus massoniana Lamb residues as sorbents,a study was conducted to assess the effects of sor-ption contact time(aging)on the desorption and biodegradation of phenol sorbed into BCs.Sorption isotherms were fitted by the Freundlich regressions to determine distribution coefficients(K_F),and desorption rate parameters were evaluated using three-site desorption model that included equilibrium,nonequilibrium,and nondesorption sites.Series dilution desorption experiences were set to measure the factor of non-desorbable phenol(f_nd) in BCs aging for 10 days.Biodegradation assays were used to investigate phenol-degrading behavior under two bacterial densities of Pseudomonas putida ATCC 11172.The results indicated that phenol sorption isotherms were well fitted by Freundlich equation (n ranged from 0.413 to 0.261,R² ranged from 0.988 to 0.993) during aging period ranged from 1 to 22 days.K_F values were strongly correlated to aging time.One thing to be noted was that f_nd values stayed at a high level and increased from 60.4% to 85.7% as prolonged aging time,which was probably attributed to the abundant surface areas and ample micro pore area (117.7 m²·g^-1) of BCs.For all aged BCs,the sorbed phenol in readily desorption sites shifted into resistant desorption sites during aging.Reduced biodegradation of sorbed chemical were observed during aging period.However,there was no statistically significant difference in biodegradation rate between two studied bacterial densities.Another noteworthy result in our study was that some part of sorbed phenol in non-desorbable sites could be biodegraded.