Nanoenvirology Research Group, Department of Civil and Environmental Engineering, North Dakota State University, Fargo, ND, 58105, USA.
Chemosphere. 2020 Aug;252:126639. doi: 10.1016/j.chemosphere.2020.126639. Epub 2020 Mar 29.
Excess fluoride (F, >1.5 mg F/L) in drinking water affects >260 million people across the globe and leads to dental and skeletal fluorosis. In this study, commercially available granular activated carbon (GAC) was modified with 0.3 M citric acid to get citric acid modified GAC (CAGAC). Over 70% of fluoride was removed in the first 60 min by CAGAC, whereas unmodified GAC removed only 30%. There were negligible interferences by co-existing ions (NO, Cl, HCO, SO PO) and organic matters. Maximum adsorption capacity of CAGAC was two times (1.65 mg/g) that of unmodified GAC (0.88 mg/g). Dubinin-Radushkevich (D-R) isotherm described the experimental data well indicating that ion exchange was involved in fluoride removal. CAGAC worked effectively over a wide range of pH (2-10) even though the point-of-zero-charge (PZC) was 4.89, and so the removal was not controlled by electrostatic interaction alone; surface adsorption and intra-particle diffusion were the rate-determining processes.
饮水中过量的氟化物（F，>1.5mg F/L）影响了全球超过 2.6 亿人，导致氟斑牙和氟骨症。在这项研究中，商用颗粒活性炭（GAC）用 0.3M 柠檬酸进行改性，得到柠檬酸改性 GAC（CAGAC）。CAGAC 在最初的 60 分钟内去除了超过 70%的氟化物，而未改性的 GAC 仅去除了 30%。共存的离子（NO、Cl、HCO、SO PO）和有机物几乎没有干扰。CAGAC 的最大吸附容量是未改性 GAC（0.88mg/g）的两倍（1.65mg/g）。Dubinin-Radushkevich（D-R）等温线很好地描述了实验数据，表明离子交换参与了氟化物的去除。CAGAC 在很宽的 pH 值范围内（2-10）都能有效工作，尽管零电荷点（PZC）为 4.89，因此去除过程不仅仅受静电相互作用的控制；表面吸附和颗粒内扩散是速率决定过程。
