铁基纳米粒子@沙棘枝炭复合材料的制备及其废水处理性能研究

发布时间：2018-06-27 12:54

本文选题：沙棘枝炭 + 复合材料　；参考：《长安大学》2017年硕士论文

【摘要】：活性炭吸附法,是一种广泛用于去除水中污染物的废水处理方法,但是成本较高的商用活性炭,增加了废水处理的运行成本。基于此,利用农业废弃生物质制备活性炭近年来得到了广泛关注。沙棘是一种落叶灌木,广泛分布在高海拔地区。然而,在沙棘果采摘过程中产生的沙棘枝条,因为随意丢弃和就地焚烧,已经引起了一系列的环境污染问题。沙棘枝条作为一个典型的富碳、廉价、资源量丰富的农业固体废物,是一种可持续生产的、天然来源的生物碳,适用于制备活性炭。但是单一的沙棘枝炭吸附无法达到低成本、高效率和无二次污染等目的。因此,在沙棘枝炭的表面引入铁基纳米粒子,增加比表面积提高吸附性能的同时,构建起非均相Fenton体系,实现吸附剂的循环再生,防止二次污染进一步降低成本,得到新型的复合吸附材料。将所制备的复合吸附材料应用于抗生素废水和染料废水处理领域,并考察了该复合材料的吸附和再生性能。具体研究内容如下:(1)以废弃沙棘枝条为基体,浸渍铁离子后,通过热裂解法制备了Fe_3O_4@沙棘枝炭复合吸附剂。SEM和EDS结果表明纳米Fe_3O_4颗粒粒径约为40 nm,在炭表面呈部分覆盖,单分散态。XRD表明生成的纳米Fe_3O_4为面心立方晶型,碳为无晶型。以强力霉素废水为处理对象,探讨了pH、吸附时间及初始浓度对吸附去除性能的影响,并对吸附过程进行了动力学、等温模型和热力学分析。结果表明复合吸附剂在碱性条件下表现出较好的吸附能力,吸附量随着时间的增加而增加,初始浓度越大,平衡吸附量也越大,但去除率却随之降低。吸附过程符合准二级动力学方程和Freundlich型等温模型,该吸附是自发的吸热过程,吸附机理包括化学吸附和物理吸附。通过构造非均相Fenton反应体系,表面富集有强力霉素的Fe_3O_4@沙棘枝炭吸附剂可实现有效再生,重复使用。(2)通过热裂解法经一步合成了Fe_3O_4@沙棘枝炭复合吸附剂。进行了XRD、SEM结构表征和磁性检测。结果表明沙棘枝炭呈无定形态,Fe_3O_4晶型为面心立方型。粒径约为41 nm,在沙棘枝炭表面呈孤岛状分布。微观负载Fe_3O_4纳米颗粒使得Fe_3O_4@沙棘枝炭复合吸附剂展示出了宏观磁性。运用BBD型响应面法,建立了Fe_3O_4@沙棘枝炭固定床吸附去除亚甲蓝固定床反应器的吸附模型,对其响应面进行了分析。结果表明响应面法建立的模型可准确描述吸附过程,且浓度、流速、pH、浓度平方和pH平方效应显著。随着流速的降低、浓度的降低和pH的升高,去除率增大。进行了再生实验,并探讨了再生机理,表明该铁系非均相Fenton氧化可有效实现吸附剂的再生重复利用。(3)在不使用交联剂的条件下,通过简单的低温水热法合成β-FeOOH@沙棘枝炭复合吸附剂。对其进行XRD、SEM和EDS表征,在表征的基础上,提出β-FeOOH@沙棘枝炭复合吸附剂的合成机理。在固定床反应器中处理抗生素废水,探讨了抗生素废水初始浓度(22-32 mg·L-1)、流速(1-3 mL·min-1)、床高(0.7-1.5 cm)和pH(2-11)对吸附去除性能的影响,并使用Thomas和Yoon-Nelson模型对吸附过程进行了拟合。此后对β-FeOOH@沙棘枝炭复合吸附剂进行了原位再生实验,在沙棘枝炭的吸附性能和β-FeOOH氧化性能的协同作用下,复合吸附剂有效再生。表明β-FeOOH@沙棘枝炭复合吸附剂在水处理领域是一种廉价有效的具有应用前景的新型材料。
[Abstract]:Activated carbon adsorption is a widely used wastewater treatment method for removing pollutants in water, but high cost commercial activated carbon has increased the operating cost of wastewater treatment. Based on this, the preparation of activated carbon from agricultural waste biomass has been widely concerned in recent years. Seabuckthorn is a deciduous shrub, widely distributed in high altitude areas. However, the Seabuckthorn branches produced during the harvest of seabuckthorn fruit have caused a series of environmental pollution problems because of the random discarding and in-situ incineration. As a typical carbon rich, cheap and abundant agricultural solid waste, the Seabuckthorn branch is a sustainable and natural source of biological carbon, which is suitable for the preparation of activated carbon. But single Seabuckthorn charcoal adsorption can not achieve the purpose of low cost, high efficiency and no two pollution. Therefore, the introduction of iron based nanoparticles on the surface of seabuckthorn branch carbon, increasing the surface area to improve the adsorption performance, construction of heterogeneous Fenton system, to realize the recycling of adsorbents, to prevent the two pollution to further reduce costs, The composite adsorbents were applied to the treatment of antibiotic wastewater and dye wastewater, and the adsorption and regeneration properties of the composite were investigated. The contents of the study were as follows: (1) the carbon composite of Fe_3O_4@ Seabuckthorn was prepared by thermal cracking after impregnating the abandoned Seabuckthorn branches and impregnating iron ions. The results of adsorbents.SEM and EDS show that the particle size of nano Fe_3O_4 particles is about 40 nm, which is partially covered on the surface of carbon, and the monodisperse.XRD shows that the nanoscale Fe_3O_4 is a surface centered cubic crystal and the carbon is amorphous. The effects of pH, adsorption time and initial concentration on the adsorption removal performance are discussed, and the adsorption is adsorbed on the adsorption and adsorption properties. The kinetics, isothermal model and thermodynamic analysis showed that the adsorption capacity of the composite adsorbent was better under the alkaline condition. The adsorption amount increased with the time, the larger the initial concentration, the greater the equilibrium adsorption, but the removal rate decreased. The adsorption process was in accordance with the quasi two stage kinetic equation and Freundlich. The adsorption is a spontaneous endothermic process. The adsorption mechanism includes chemical adsorption and physical adsorption. By constructing an heterogeneous Fenton reaction system, the surface enrichment of Fe_3O_4@ Seabuckthorn charcoal adsorbents with doxycycline can be effectively regenerated and reused. (2) the carbon composite absorption of Fe_3O_4@ Seabuckthorn was synthesized by thermal decomposition. The structure characterization and magnetic detection of XRD, SEM are carried out. The results show that the charcoal of seabuckthorn is amorphous and the Fe_3O_4 crystal is face centered cubic. The particle size is about 41 nm, and it is isolated in the surface of the charcoal surface of seabuckthorn branches. The micro load Fe_3O_4 nanoparticles show the macro magnetic properties of the Fe_3O_4@ Seabuckthorn branch carbon compound absorption agent, and use the BBD response surface. The adsorption model of Fe_3O_4@ Seabuckthorn branch carbon fixed bed adsorbed to remove methylene blue fixed bed reactor was established. The response surface of the reactor was analyzed. The results showed that the model established by the response surface method could accurately describe the adsorption process, and the concentration, flow rate, pH, concentration square and pH square effect should be significant. With the decrease of velocity, the decrease of concentration and the rise of pH. The regeneration experiment was carried out, and the regeneration mechanism was carried out, and the regeneration mechanism was discussed. It was shown that the iron-based heterogeneous Fenton oxidation could effectively reuse the adsorbents. (3) under the condition of without crosslinking agent, a simple low temperature hydrothermal method was used to synthesize the carbon composite adsorbents of the beta -FeOOH@ Seabuckthorn branch carbon. It was characterized by XRD, SEM and EDS. On the basis of the sign, the synthesis mechanism of -FeOOH@ Seabuckthorn branch carbon composite adsorbent was proposed. Treatment of antibiotic wastewater in a fixed bed reactor was carried out. The initial concentration of antibiotic wastewater (22-32 mg. L-1), flow rate (1-3 mL. Min-1), bed height (0.7-1.5 cm) and pH (2-11) on the absorption and removal performance were investigated, and the adsorption of the adsorbents by Thomas and Yoon-Nelson models was used. The process was fitted. The in situ regeneration experiment was carried out on the carbon composite adsorbent of -FeOOH@ Seabuckthorn branch. The compound adsorbent was effectively regenerated under the synergistic effect of the adsorption property of the charcoal and the oxidation performance of the beta -FeOOH. The results showed that the compound adsorbent for the beta -FeOOH@ Seabuckthorn branch carbon composite adsorbent was a cheap and effective application prospect in the field of water treatment. A new type of material.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB33;TQ424

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