氢气还原天然褐铁矿、菱铁矿制备零价铁及其除磷作用

发布时间：2018-08-31 07:52

【摘要】：随着人类对水体富营养化环境问题的关注以及对环境质量要求的提高,净化含磷污废水迫在眉睫。寻求高效、低廉的除磷材料倍受研究者的关注。新型材料纳米零价铁因其比表面积大,吸附能力强而被广泛用作吸附剂。本文利用XRD、 XPS、TG/DTG、SEM、TEM、BET等表征手段研究了铜陵天然褐铁矿及菱铁矿的矿物组成及其形貌形态特征,并通过热处理方式获得褐铁矿、菱铁矿纳米结构化相变零价铁。通过静态实验研究了不同因素(煅烧温度、初始pH值、反应时间、初始磷浓度、氧气总量、干扰离子对纳米铁除磷效率的影响以及反应动力学、吸附平衡的研究。同时将纳米零价铁作为动态柱填料并探究其除磷性能。得出以下结论：(1)铜陵天然褐铁矿主要由针铁矿(90wt%)和石英组成,褐铁矿晶体呈针状和片状,具纳米尺寸,集合体呈笋状和球状；热处理促使针铁矿进一步纳米结构化相变形成零价铁,具多孔结构、高比表面积特征。(2)铜陵天然菱铁矿矿石主要成分为菱铁矿(FeCO3),除此之外还含有少量的针铁矿、黏土、石英等杂质。菱铁矿呈菱面体形态,样品中存在的叶片状形态的物质主要为伊蒙黏土矿物,针状、棒状形态的矿物为菱铁矿经风化氧化形成的针铁矿。(3)当煅烧温度达550℃及以上,氢气流速为180mL/min,氢气分别还原天然褐铁矿和天然菱铁3h可以完全转变成纳米零价铁。通过BET数据分析和实验结果证明,随着煅烧温度升高,纳米铁对磷的去除效率先升高后逐渐降低。要保证纳米零价铁除磷效果最佳,氢气还原天然铁矿制备纳米零价铁最佳煅烧温度点是550℃。(4)通过静态实验,考察了不同煅烧温度、初始pH值、氧气总量、初始浓度、干扰离子等对纳米零价铁除磷效果的影响,通过实验确定去除效果的最佳条件,并进一步分析了纳米零价铁除磷的机理。结果显示,在弱酸且溶解氧存在的条件下,本文两种材料制备出的纳米零价铁除磷效率达95%及以上。在纳米零价铁除磷过程中,反应时间、初始磷浓度、pH值、溶解氧量对去除率影响很大。而除磷效果基本不受反应温度的影响。(5)氢气还原褐铁矿制备纳米零价铁作为动态柱填料净化模拟含磷(5mmg/L)废水可运行1年以上,磷去除效率超过99.5%,出水磷浓度达到地面水体环境质量II类标准(0.025mg/L)。
[Abstract]:With the attention to eutrophication environment and the improvement of environmental quality, it is urgent to purify the wastewater containing phosphorus. The search for high efficiency and low-cost phosphorus removal materials has attracted the attention of researchers. Nanocrystalline zero-valent iron is widely used as adsorbent because of its large specific surface area and strong adsorption capacity. In this paper, the mineral composition and morphology of natural limonite and siderite in Tongling were studied by means of XRD, XPS,TG/DTG,SEM,TEM,BET and other characterizations. Through heat treatment, limonite and siderite nano-structured phase change zero valent iron were obtained. The effects of different factors (calcination temperature, initial pH value, reaction time, initial phosphorus concentration, total oxygen, interference ions) on phosphorus removal efficiency, reaction kinetics and adsorption equilibrium of nanocrystalline iron were studied by static experiments. At the same time, nanocrystalline zero valent iron was used as dynamic column filler and its phosphorus removal performance was investigated. The main conclusions are as follows: (1) Tongling natural limonite is mainly composed of goethite (90 wt%) and quartz. The limonite crystal is acicular and flake with nanometer size and the aggregate is bamboo shoot and globular. Heat treatment promotes goethite to form zero-valent iron with porous structure and high specific surface area. (2) the main component of Tongling natural siderite ore is siderite (FeCO3), in addition to a small amount of goethite and clay, An impurity, such as quartz. Siderite is in the rhombohedral form, and the material in the leaf shape of the sample is mainly Aemon clay mineral, acicular and rod-like minerals are goethite formed by weathering of siderite. (3) when the calcination temperature is 550 鈩，

本文编号：2214364