牡蛎壳负载零价纳米铁的制备及其在去除水溶液中天然有机物方面的应用。
Preparation and application of oyster shell supported zero valent nano scale iron for removal of natural organic matter from aqueous solutions.
机构信息
Department of Environmental Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
Department of Environmental Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran ; Center for Water Quality Research (CWQR), Institute for Environmental Research (IER), Tehran University of Medical Sciences, Tehran, Iran.
出版信息
J Environ Health Sci Eng. 2014 Dec 19;12(1):146. doi: 10.1186/s40201-014-0146-y. eCollection 2014.
BACKGROUND
In this Research, oyster shell supported zero valent iron nanoparticles were prepared and applied for the removal of natural organic matters (NOMs) from aqueous solutions under different experimental conditions.
METHODS
The nanoadsorbents prepared by wet impregnation method, then characterized using Scanning Electron Microscopy, Energy Dispersive Spectroscopy, X-Ray Fluorescence and BET analysis. Adsorption test was done in a batch reactor and the effects of different parameters such as initial adsorbate concentration, adsorbent dose, adsorption kinetic, pH, and temperature on removal of NOMs (humic acid as the indicator) were studied.
RESULTS
Results showed that particle size of nanoadsorbent was in the range of 60-83 nm, and surface area and micropore volume as 16.85 m(2)/g and 0.021 m(3)/g, respectively; the main elements of adsorbent were Ca, O, Fe and Na and lime, as high as about 94.25% was the main structural component of the total weight. Produced nanoadsorbent was not soluble in water. It was also shown that by increasing the nanoadsorbent dose from 0.5 to 5 g/100 ml, the removal of humic acid increased from 62.3% to 97.4%. An inverse relationship was found between initial concentration and adsorption capacity, so that a decreasing rate of 33% for humic acid removal was observed by increasing pH from 5 to 10. Temperature increase from 25°C to 40°C, resulted in an increase in humic acid removal from 76.8% to 91.4% and its adsorption on the adsorbent could be better described by Freundlich isotherm (n = 0.016, Kf = 0.013 and R(2) = 0.74). The most fitted adsorption kinetic model was pseudo-second order model.
CONCLUSIONS
The chemical structure of nanoadsorbent was proper and free from harmful substances. Despite the relative good condition of the effective surface, due to the large size of the shell, the overall micropore volume was low. Hence the qualitative characteristics the adsorbent caused the absorption capacity of humic acid to be low (0.96 mg/g).
背景
在这项研究中，制备了牡蛎壳负载零价铁纳米粒子，并在不同实验条件下将其应用于从水溶液中去除天然有机物（NOMs）。
方法
采用湿法浸渍法制备纳米吸附剂，然后采用扫描电子显微镜、能谱分析、X 射线荧光和 BET 分析对其进行表征。在间歇式反应器中进行吸附试验，研究了初始吸附质浓度、吸附剂剂量、吸附动力学、pH 值和温度等不同参数对 NOMs（以腐殖酸为指示剂）去除的影响。
结果
结果表明，纳米吸附剂的粒径范围为 60-83nm，比表面积和微孔体积分别为 16.85m²/g 和 0.021m³/g；吸附剂的主要元素为 Ca、O、Fe 和 Na，石灰的含量高达约 94.25%，是总重量的主要结构成分。所制备的纳米吸附剂不溶于水。研究还表明，随着纳米吸附剂剂量从 0.5 增加到 5g/100ml，腐殖酸的去除率从 62.3%增加到 97.4%。初始浓度与吸附容量之间呈反比关系，因此 pH 值从 5 增加到 10 时，腐殖酸的去除率下降了 33%。温度从 25°C 升高到 40°C，腐殖酸的去除率从 76.8%增加到 91.4%，其在吸附剂上的吸附可以更好地用 Freundlich 等温线描述（n=0.016，Kf=0.013，R²=0.74）。最拟合的吸附动力学模型是准二级模型。
结论
纳米吸附剂的化学结构合适，不含有害物质。尽管有效表面的条件相对较好，但由于外壳的尺寸较大，总微孔体积较低。因此，吸附剂的定性特征导致腐殖酸的吸附容量较低（0.96mg/g）。
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