利用吸附染料的废弃水滑石去除水中重金属研究

发布时间：2018-10-26 12:56

【摘要】：染料工业排放的废水一直都是国内外难处理的工业废水之一,对环境污染严重,吸附法因其具有较高的选择性,成本低廉而受到关注,但吸附染料后的废弃吸附剂如何处理再生,成为国内外研究的重点。水滑石,又称层柱状双金属氢氧化物(Layered double hydroxide,简称LDH),因其特有的记忆效应和层板阴离子的可交换性使其在吸附染料的废弃吸附剂的再利用方面展现出广阔的应用前景。本文用吸附刚果红的镁铝水滑石和磁性镁铝水滑石合成并表征了两种金属氧化物/碳复合材料,选取三种重金属污染物作为研究对象,并采用静态的批次平衡实验研究其吸附性能,研究结果如下:采用低饱和共沉淀法制备了镁铝水滑石(Mg/Al-LDH)和磁性镁铝水滑石(Fe_3O_4@LDH),加入刚果红染料至吸附饱和得到废弃水滑石,经高温焙烧后得到LDO/C和Fe_3O_4@LDO/C复合材料,并进行了FTIR、XRD、SEM、TG、EDS和BET等表征,结果表明合成的复合材料具有Mg(Al)O和C的特征衍射峰,Fe_3O_4@LDO/C复合材料还具有Fe_3O_4的特征衍射峰,将LDO/C和Fe_3O_4@LDO/C复合材料分散在水中后,由于其“记忆效应”又恢复原有的水滑石结构,出现镁铝水滑石特征衍射峰。LDO/C复合材料对重金属Cu~(2+)、Cd~(2+)和Pb~(2+)的吸附实验研究表明,该复合材料对三种重金属的吸附效果良好,最佳吸附用量为0.05 g,吸附平衡时间分别为300 min、60 min和500 min,吸附速率大小顺序为Pb~(2+)Cu~(2+)Cd~(2+),吸附动力学数据均符合颗粒扩散模型,同时也符合拟二级动力学模型。LDO/C复合材料吸附Cu~(2+)和Cd~(2+)的过程均符合Langmuir模型,吸附Pb~(2+)的过程符合Langmuir和Freundlich吸附等温线模型,最大吸附容量分别可达13.64 mmol/g(Cu~(2+))、15.72 mmol/g(Cd~(2+))和10.31 mmol/g(Pb~(2+))。Fe_3O_4@LDO/C复合材料对重金属Cu~(2+)、Cd~(2+)和Pb~(2+)的吸附实验研究表明,该复合材料对三种重金属的吸附效果良好,吸附能力明显高于Fe_3O_4@LDH和吸附完染料后的废弃磁性水滑石。Fe_3O_4@LDO/C复合材料对重金属Cu~(2+)、Cd~(2+)和Pb~(2+)的吸附动力学数据均符合颗粒扩散模型,同时也符合拟二级动力学模型。吸附等温线均符合Langmuir模型,吸附容量分别达3.96 mmol/g(Cu~(2+))、4.76 mmol/g(Cd~(2+))和1.86 mmol/g(Pb~(2+)),且吸附剂能够通过磁分离技术实现固液的快速分离。
[Abstract]:The wastewater discharged by dye industry has been one of the refractory industrial wastewater at home and abroad, and has caused serious environmental pollution. Adsorption method has attracted much attention because of its high selectivity and low cost. However, how to treat and regenerate the waste adsorbent after dye adsorption has become the focus of research at home and abroad. Hydrotalcite, also known as layered bimetallic hydroxide (Layered double hydroxide,), has a broad application prospect in the reuse of waste adsorbent for dye adsorption because of its special memory effect and exchangeability of laminate anions. In this paper, two kinds of metal oxide / carbon composites were synthesized and characterized by magnesium-aluminum hydrotalcite and magnesium-aluminum hydrotalcite adsorbed on Congo red. Three kinds of heavy metal pollutants were selected as research objects. The adsorption properties of magnesium-aluminum hydrotalcite (Mg/Al-LDH) and magnetic magnesia-aluminum-hydrotalcite (Fe_3O_4@LDH) were studied by static batch equilibrium test. The results are as follows: (1) magnesia-aluminum hydrotalcite (Mg/Al-LDH) and magnesia-aluminum hydrotalcite (Fe_3O_4@LDH) were prepared by low saturation coprecipitation method. The waste hydrotalcite was obtained by adding Congo red dye to adsorption saturation. LDO/C and Fe_3O_4@LDO/C composites were obtained by calcination at high temperature and characterized by FTIR,XRD,SEM,TG,EDS and BET. The results show that the synthesized composites have the characteristic diffraction peaks of Mg (Al) O and C, and the Fe_3O_4@LDO/C composites have the characteristic diffraction peaks of Fe_3O_4. When the LDO/C and Fe_3O_4@LDO/C composites were dispersed in water, the characteristic diffraction peaks of MgAl hydrotalcite appeared due to its "memory effect". The adsorption experiments of Cd~ (2) and Pb~ (2) show that the composite has a good adsorption effect on the three heavy metals. The optimum adsorption dosage is 0. 05 g and the adsorption equilibrium time is 300 min,60 min and 500 min, respectively. The adsorption rate was in the order of Pb~ (2) Cu~ (2) Cd~ (2), and the adsorption kinetic data were in accordance with the particle diffusion model. The process of adsorption of Cu~ (2) and Cd~ (2) of LDO/C composite is in accordance with Langmuir model, and the process of adsorption of Pb~ (2) accords with the isotherm model of Langmuir and Freundlich. The maximum adsorption capacity was 13.64 mmol/g (Cu~ (2), 15.72 mmol/g (Cd~ (2) and 10.31 mmol/g (Pb~ (2). Fe_3O_4@LDO/C) for Cu~ (2), respectively. The adsorption experiments of Cd~ (2) and Pb~ (2) show that the composite has good adsorption effect on three heavy metals. The adsorption capacity of Fe_3O_4@LDO/C composite was significantly higher than that of Fe_3O_4@LDH and waste magnetic hydrotalcite after dye adsorption. The adsorption kinetic data of Cd~ (2) and Pb~ (2) are in accordance with the particle diffusion model and the pseudo-second-order kinetic model. The adsorption isotherms accord with the Langmuir model, and the adsorption capacities are 3.96 mmol/g (Cu~ (2), 4.76 mmol/g (Cd~ (2) and 1.86 mmol/g (Pb~ (2), respectively. And the adsorbent can realize the rapid separation of solid and liquid by magnetic separation technology.
【学位授予单位】：济南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703

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