FeCl_(3)沉淀法在水溶液中去除药物抗生素的表现

Performance of FeCl_(3) Precipitation Method in Removing Pharmaceutical Antibiotics from Aqueous Solutions

药物抗生素(PA)残留物普遍存在于土壤和水环境中;因受去除效率及可产生致癌副产物的制约,目前的生物或光化学降解方法难以有效去除PA,且金属离子与PA的吸附/络合机制尚不清楚。本文用FeCl_(3)从水溶液中去除两种PA—盐酸左氧氟沙星(LH)和盐酸坦索罗辛(TH);发现pH=7.5~8.5时,铁以Fe-PA沉淀物(Fe-PAp)形式将PA从水溶液中分离;连续沉淀5次后,90.3%的LH和87.5%TH被去除;分析LH、TH和Fe-PAp的波峰特征,发现:1)LH和TH主要红外峰:3 433和3 329 cm^(-1)(羧酸OH和NH2)、1 676 cm^(-1)(-COO-)、1 467 cm^(-1)(脂肪族C-H)和1 022 cm^(-1)(-S=O),2)Fe-PAp中前述红外峰强度下降或完全消失。通过化学键分析表明:在Fe-PAp形成过程中,电子从PA内各种官能团转移到Fe3+的空d轨道,形成π-d电子键系统。FeCl_(3)应用广泛:1)作为一种高效且有应用前景的无机吸附剂,能够从水中去除PA,可实现大规模分离生活和工业废水中的有机污染物;2)Fe-PAp的形成表明金属-有机复合物可以在碱性土壤和水中长期稳定,解释了Fe-DOM复合物在环境中的长期稳定/固存机制。

Pharmaceutical antibiotic(PA) residues are pervasive in soil and water environments;current biological or photochemical degradation methods are difficult to effectively remove PA residues due to constraints on removal efficiency and possible carcinogenic by-products. Up to now, it is not clear about the adsorption/complexation mechanism of metal ions with PA. In this work, two commonly used PAs-levofloxacin hydrochloride(LH) and tamsulosin hydrochloride(TH) were removed from aqueous solution using FeCl_(3);it was found that Fe3+in the form of Fe-PA precipitate(Fe-PAp) separated PA from aqueous solution at pH=7.5-8.5. About 90.3% and 87.5% of LH and TH were removed in the form of Fe-PAp after five successive precipitations from the corresponding aqueous solutions with FeCl_(3), respectively. The IR characteristics of original LH and TH and Fe-PAp were also studied comparatively, and it was found that: 1) the main IR peaks of LH and TH exhibited: 3 433 and 3 329 cm^(-1)(carboxylic acids OH and NH2), 1 676 cm^(-1)(-COO-), 1 467 cm^(-1)(aliphatic C-H) and 1 022 cm^(-1)(-S=O), 2) the intensity of the aforementioned IR peaks in Fe-PAp decreased or disappeared completely. The chemical bonding analysis shows that during the formation of Fe-PAp, electrons are transferred from various PA functional groups to the unpaired d orbitals of Fe3+, forming a π-d electron bonding system. FeCl_(3)has a wide range of practical applications: 1) as an efficient and promising inorganic adsorbent for the removal of PA from water, which in turn may open new fields in the large-scale separation of organic pollutants from domestic and industrial wastewater;2) Fe-PAp formation indicates that metal-organic complexes can be stabilized in alkaline soils and water for a long time, explaining the long-term stabilization/sequestration mechanism of Fe-DOM complexes in the environment.