新兴含氮消毒副产物较常规消毒副产物的浓度更低但毒性更强,去除难度更大。 提出采用活性 炭对形成含氮消毒副产物的前体物(以色氨酸为例)进行去除,比较常规和新型活性炭对前体物的去除性 能,并阐释原因。 研究发现:粉末状活性炭(PAC)和活性炭纤维(ACF)对色氨酸的最大等温吸附量分别为 37. 31 mg·g-1 和 178. 57 mg·g-1;对色氨酸的吸附速率分别是 5. 95×10-2 sec-1 和 1. 7×10-3 sec -1;两种类型的活性炭的吸附动力学均属于伪二阶动力学,且都符合 Langmuir 吸附等温方程(r2≥0. 99);ACF 比 PAC 具有更大的比表面积,更大的总孔体积、更小的平均孔径和更多的表面官能团。 在 15 ℃ ~ 45 ℃ 范围内,两者对色氨酸均是熵推动的自发吸附,吸附推动力先增加后减小,但 PAC 和 ACF 对色氨酸的吸附分别为物理吸附和化学吸附;研究结果表明:由于含氮消毒副产物前体物的分子量普遍较小,因此 ACF 更适用于其前体物的去除;由于 ACF 孔径较小,吸附速率较慢,因此需要保证充足的吸附接触时间。
Emerging nitrogen-containing disinfection by-products have lower concentrations than conventional disinfection by-products but are more toxic and more difficult to remove. This study proposes to use activated carbon to remove the precursors that form nitrogen-containing disinfection by-products take tryptophan as an example compare the removal performance of conventional and new activated carbons for precursors and explain the mechanism. The study found that the maximum isotherm adsorption capacity of powdered activated carbon PAC and activated carbon fiber ACF for tryptophan were 37. 31 and 178. 57 mg?? g-1 respectively and the adsorption rates of tryptophan were 5. 95 × 10-2 sec-1 and 1. 7 × 10-3 sec-1 respectively. The adsorption of tryptophan on both types of activated carbon belonged to the Langmuir model r2 ≥0. 99 and the adsorption kinetics were both pseudo-second-order kinetic models. ACF had a larger specific surface area a larger total pore volume a smaller average pore size and more surface functional groups than PAC. In the range of 15 ℃ ~45 ℃ ACF and PAC were both entropy-driven spontaneous adsorption of tryptophan and the adsorption driving force first increased and then decreased but the adsorption of tryptophan by PAC and ACF is physical adsorption and chemical adsorption respectively. The research results show that because the molecular weight of the precursors of the nitrogen-containing disinfection by-products is generally small ACF is more suitable for the removal of its precursors. Because the ACF has a smaller pore size and a slower adsorption rate it is necessary to ensure sufficient adsorption contact time.
FAN Zi-hong, ZHOU Yu-ting, YANG Hai-lin, ZHANG Hui-jun. Performances of Activated Carbons for Removal of Tryptophan as a Model Precursor of Nitrogenous DBPs[J]. Journal of Chongqing Technology and Business University(Natural Science Edition）,2022,39(6):14-21