Department of Civil & Environmental Engineering, University of Iowa, 4105 Seamans Center, Iowa City, Iowa 52242, United States.
IIHR-Hydroscience & Engineering, 100 C. Maxwell Stanley Hydraulics Laboratory, Iowa City, Iowa 52242, United States.
Environ Sci Technol. 2020 Nov 17;54(22):14694-14705. doi: 10.1021/acs.est.0c04187. Epub 2020 Oct 29.
Widespread application of neonicotinoids has led to their proliferation in waters. Despite low neonicotinoid hydrophobicity, our prior studies implicated granular activated carbon (GAC) in neonicotinoid removal. Based on known receptor binding characteristics, we hypothesized that the insecticidal pharmacophore influences neonicotinoid sorption. Our objectives were to illuminate drivers of neonicotinoid sorption for parent neonicotinoids (imidacloprid, clothianidin, thiamethoxam, and thiacloprid) and pharmacophore-altered metabolites (desnitro-imidacloprid and imidacloprid urea) to GAC, powdered activated carbon, and carbon nanotubes (CNTs). Neonicotinoid sorption to GAC was extensive and largely irreversible, with significantly greater sorption of imidacloprid than desnitro-imidacloprid. Imidacloprid and imidacloprid urea (electronegative pharmacophores) sorbed most extensively to nonfunctionalized CNTs, whereas desnitro-imidacloprid (positive pharmacophore) sorbed most to COOH-CNTs, indicating the importance of charge interactions and/or hydrogen bonding between the pharmacophore and carbon surface. Water chemistry parameters (temperature, alkalinity, ionic strength, and humic acid) inhibited overall neonicotinoid sorption, suggesting that pharmacophore-driven sorption in real waters may be diminished. Analysis of a full-scale drinking water treatment plant GAC filter influent, effluent, and spent GAC attributes neonicotinoid/metabolite removal to GAC under real-world conditions for the first time. Our results demonstrate that the neonicotinoid pharmacophore not only confers insecticide selectivity but also impacts sorption behavior, leading to less effective removal of metabolites by GAC filters in water treatment.
新烟碱类杀虫剂的广泛应用导致其在水中大量存在。尽管新烟碱类杀虫剂的疏水性较低，但我们之前的研究表明颗粒活性炭（GAC）对新烟碱类杀虫剂的去除起作用。基于已知的受体结合特征，我们假设杀虫药效团影响新烟碱类杀虫剂的吸附。我们的目标是阐明亲代新烟碱类杀虫剂（吡虫啉、噻虫啉、噻虫嗪和噻虫酰胺）和药效团改变的代谢物（去硝吡虫啉和吡虫啉脲）在颗粒活性炭、粉末活性炭和碳纳米管（CNTs）上的吸附驱动力。新烟碱类杀虫剂在 GAC 上的吸附非常广泛且大部分为不可逆吸附，吡虫啉的吸附量明显大于去硝吡虫啉。带负电药效团的吡虫啉和吡虫啉脲（带负电药效团）在未功能化的 CNTs 上的吸附最为广泛，而带正电药效团的去硝吡虫啉在 COOH-CNTs 上的吸附最为广泛，这表明电荷相互作用和/或药效团与碳表面之间的氢键在吸附中非常重要。水化学参数（温度、碱度、离子强度和腐殖酸）抑制了新烟碱类杀虫剂的整体吸附，这表明在实际水体中，药效团驱动的吸附可能会减弱。对一个全规模饮用水处理厂 GAC 过滤器的进水、出水和使用过的 GAC 的分析，首次在实际条件下分析了 GAC 对新烟碱类杀虫剂/代谢物的去除作用。我们的研究结果表明，新烟碱类杀虫剂的药效团不仅赋予了杀虫剂的选择性，而且还影响了吸附行为，导致 GAC 过滤器在水处理中对代谢物的去除效果降低。
