使用镧盐高效混凝去除氟化物：氟的分布和化学行为
Frontiers in Chemistry
(
IF
4.2
)
Pub Date : 2022-03-04
, DOI:
10.3389/fchem.2022.859969
Xiaocong Zhong
1,
2
,
Chen Chen
1
,
Kang Yan
1
,
Shuiping Zhong
1
,
Ruixiang Wang
1
,
Zhifeng Xu
3
Affiliation
Faculty of Materials Metallurgy and Chemistry, Jiangxi University of Science and Technology, Ganzhou, China.
State Key Laboratory of Separation and Comprehensive Utilization of Rare Metals, Guangzhou, China.
Jiangxi College of Applied Technology, Ganzhou, China.
摘要：由于 La 3+对氟离子的强亲和力，负载 La 的吸收剂已被广泛报道用于去除氟化物。在此，研究了使用镧盐从烟气洗涤废水中化学去除氟化物。已使用离子选择电极、分析天平、扫描电子显微镜和 X 射线衍射仪研究了过滤残留物的游离 F -浓度、相组成和形态以及氟的分布。结果表明，在La/F摩尔比≥1:3.05时，大部分氟以LaF的形式存在X3−X络合物，导致除氟失败。在1:3.20≤La/F摩尔比≤1:3.10时，有利于LaF 3的形成。然而，共存的 LaFX3−X倾向于吸附在LaF 3颗粒表面，导致形成含有大量LaF 3 ·LaF的胶体溶液X3−X悬浮物。在 1:3.10 的优化 La/F 摩尔比下，在保持 6.42 mg L -1的氟浓度的情况下，获得了 97.86% 的氟化物去除率。考虑到存在带正电的 LaFX3−X和 LaF 3 ·LaFX3−X, 提出并研究了使用镧盐和带负电的 SiO 2的混凝去除氟化物·nH 2 O 胶体颗粒，即原位假如通过Na 2 SiO 3在 pH 值接近 5.5 时水解。在1:3.00的La/F摩尔比和0.50g L -1的Na 2 SiO 3剂量下，在保持2.24mg L -1的氟浓度的情况下，获得了99.25％的氟化物去除。当Na 2 SiO 3剂量增加到1.00 g L -1时，保留氟浓度可以进一步降低到0.80 mg L -1。
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Efficient Coagulation Removal of Fluoride Using Lanthanum Salts: Distribution and Chemical Behavior of Fluorine
Abstract: La-loaded absorbents have been widely reported for fluoride removal due to the strong affinity of La3+ towards fluoride ion. Herein, chemical removal of fluoride from flue gas scrubbing wastewater using lanthanum salt is investigated. The retaining free F− concentration, phase composition and morphology of filtration residues, and the distribution of fluorine have been investigated using ion-selective electrode, analytical balance, scanning electron microscopy, and X-ray diffractor. The results show that at La/F molar ratio ≥1:3.05, the majority of fluorine exists as LaFx3−x complexes, leading to the failure of fluoride removal. At 1:3.20 ≤ La/F molar ratio ≤1:3.10, the formation of LaF3 is facilitated. However, co-existing LaFx3−x tends to absorb on the surface of LaF3 particles, leading to the formation of colloidal solution with large numbers of LaF3·LaFx3−x suspended solids. At an optimized La/F molar ratio of 1:3.10, a fluoride removal of 97.86% is obtained with retaining fluorine concentration of 6.42 mg L−1. Considering the existing of positively charged LaFx3−x and LaF3·LaFx3−x, coagulation removal of fluoride is proposed and investigated using lanthanum salts and negatively charged SiO2·nH2O colloidal particles, which is in-situ provided via Na2SiO3 hydrolysis at pH near 5.5. At a La/F molar ratio of 1:3.00 and Na2SiO3 dose of 0.50 g L−1, a fluoride removal of 99.25% is obtained with retaining fluorine concentration of 2.24 mg L−1. When Na2SiO3 dose increases to 1.00 g L−1, the retaining fluorine concentration could be further reduced to 0.80 mg L−1.
更新日期：2022-03-04