Shen Xiaolong, Hussain Tariq, Mitchek Micala, Wong Joe, Reible Danny
Department of Civil, Environmental, and Construction Engineering, Texas Tech University, 911 Boston Ave., Lubbock, TX 79409, USA.
ADA Carbon Solution, Inc, 8051 E. Maplewood Ave, Suite 210, Greenwood Village, Colorado 80111, USA.
Water Res. 2023 Jun 1;236:119978. doi: 10.1016/j.watres.2023.119978. Epub 2023 Apr 13.
Activated carbon (AC) has been applied widely in water treatment as a strong sorbent for organic contaminants and, more recently, in-situ treatment and capping for remediating legacy contaminants. In some sediment environments, the sorption kinetics onto AC may significantly impact remedial performance, particularly for large, highly hydrophobic contaminants such as PCBs, but there is limited kinetic data on such compounds. In this study, batch experiments were conducted over 52 weeks to measure PCB adsorption kinetics on 2 ACs in granular (1.1 mm diameter) and powdered (0.02 mm) form using polydimethylsiloxane (PDMS) fibers to measure aqueous concentrations over time. The experiment was conducted in glass containers with water at known PCB concentration and containing 10 mg/L natural organic matter (NOM) and activated carbon. Blanks without activated carbon were used to estimate kinetics and equilibrium uptake to PDMS and NOM. The PDMS measured aqueous concentration in AC containing slurries was then used to estimate kinetics and equilibrium uptake of the various PCBs onto the AC. Achieving equilibration of PCBs onto the powdered activated carbon (PAC) was accomplished in days to weeks, but granular activated carbon (GAC) uptake was not complete for some high molecular weight congeners in a year. The data were used to fit linear driving force models with both linear and Freundlich models of equilibrium. The models were then used to predict uptake onto powdered and granular AC during in-situ capping and treatment using the CapSim model. Slow kinetics can significantly limit the performance of granular AC in high upwelling (> 1-10 cm/day) environments. This study demonstrates the usage of polymeric passive samplers to explore sorption kinetics and equilibrium for low solubility compounds as well as the differences in performance of granular and powdered forms of AC for remediation of PCB contaminated sediment.
活性炭（AC）作为一种对有机污染物具有强大吸附能力的吸附剂，已广泛应用于水处理领域，最近还用于原位处理和覆盖修复遗留污染物。在一些沉积物环境中，活性炭的吸附动力学可能会显著影响修复效果，特别是对于多氯联苯等大型、高疏水性污染物，但关于此类化合物的动力学数据有限。在本研究中，进行了为期52周的批次实验，以测量颗粒状（直径1.1毫米）和粉末状（0.02毫米）两种活性炭对多氯联苯的吸附动力学，使用聚二甲基硅氧烷（PDMS）纤维随时间测量水溶液浓度。实验在玻璃容器中进行，容器中的水具有已知的多氯联苯浓度，并含有10毫克/升的天然有机物（NOM）和活性炭。使用不含活性炭的空白样品来估计PDMS和NOM的动力学和平衡吸附量。然后，用PDMS测量含活性炭浆液中的水溶液浓度，以估计各种多氯联苯在活性炭上的动力学和平衡吸附量。多氯联苯在粉末状活性炭（PAC）上达到平衡需要数天至数周时间，但对于一些高分子量同系物，颗粒状活性炭（GAC）在一年内并未完全吸附。这些数据用于拟合线性驱动力模型以及平衡的线性和弗伦德利希模型。然后，使用CapSim模型，这些模型被用于预测原位覆盖和处理过程中多氯联苯在粉末状和颗粒状活性炭上的吸附情况。缓慢的动力学可能会显著限制颗粒状活性炭在高上升流（>1 - 10厘米/天）环境中的性能。本研究展示了聚合物被动采样器在探索低溶解度化合物的吸附动力学和平衡方面的应用，以及颗粒状和粉末状活性炭在修复多氯联苯污染沉积物方面的性能差异。
