Fan Yingzheng, Huang Yuankai, Linthicum Will, Liu Fangyuan, Beringhs André O'Reilly, Dang Yanliu, Xu Zhiheng, Chang Shing-Yun, Ling Jing, Huey Bryan D, Suib Steven L, Ma Anson W K, Gao Pu-Xian, Lu Xiuling, Lei Yu, Shaw Montgomery T, Li Baikun
Department of Civil & Environmental Engineering, University of Connecticut, Storrs, Connecticut 06269, United States.
Department of Materials Science & Engineering, University of Connecticut, Storrs, Connecticut 06269, United States.
ACS Sens. 2020 Oct 23;5(10):3182-3193. doi: 10.1021/acssensors.0c01422. Epub 2020 Oct 1.
Long-term accurate and continuous monitoring of nitrate (NO) concentration in wastewater and groundwater is critical for determining treatment efficiency and tracking contaminant transport. Current nitrate monitoring technologies, including colorimetric, chromatographic, biometric, and electrochemical sensors, are not feasible for continuous monitoring. This study addressed this challenge by modifying NO solid-state ion-selective electrodes (S-ISEs) with poly(tetrafluoroethylene) (PTFE, (CF)). The PTFE-loaded S-ISE membrane polymer matrix reduces water layer formation between the membrane and electrode/solid contact, while paradoxically, the even more hydrophobic PTFE-loaded S-ISE membrane prevents bacterial attachment despite the opposite approach of hydrophilic modifications in other antifouling sensor designs. Specifically, an optimal ratio of 5% PTFE in the S-ISE polymer matrix was determined by a series of characterization tests in real wastewater. Five percent of PTFE alleviated biofouling to the sensor surface by enhancing the negative charge (-4.5 to -45.8 mV) and lowering surface roughness (: 0.56 ± 0.02 nm). It simultaneously mitigated water layer formation between the membrane and electrode by increasing hydrophobicity (contact angle: 104°) and membrane adhesion and thus minimized the reading (mV) drift in the baseline sensitivity ("data drifting"). Long-term accuracy and durability of 5% PTFE-loaded NO S-ISEs were well demonstrated in real wastewater over 20 days, an improvement over commercial sensor longevity.
长期准确且连续地监测废水和地下水中硝酸盐（NO）的浓度对于确定处理效率和追踪污染物迁移至关重要。当前的硝酸盐监测技术，包括比色法、色谱法、生物法和电化学传感器，都不适用于连续监测。本研究通过用聚四氟乙烯（PTFE，(CF)）对NO固态离子选择电极（S-ISEs）进行改性来应对这一挑战。负载PTFE的S-ISE膜聚合物基质减少了膜与电极/固体接触之间水层的形成，而矛盾的是，尽管在其他防污传感器设计中采用了亲水性改性的相反方法，但负载PTFE的S-ISE膜疏水性更强，可防止细菌附着。具体而言，通过在实际废水中进行一系列表征测试，确定了S-ISE聚合物基质中PTFE的最佳比例为5%。5%的PTFE通过增强负电荷（-4.5至-45.8 mV）和降低表面粗糙度（: 0.56 ± 0.02 nm）减轻了传感器表面的生物污染。它同时通过增加疏水性（接触角：104°）和膜附着力减轻了膜与电极之间水层的形成，从而将基线灵敏度中的读数（mV）漂移降至最低（“数据漂移”）。在实际废水中经过20天的测试，充分证明了负载5% PTFE的NO S-ISEs的长期准确性和耐用性，这比商业传感器的寿命有所提高。
