典型含铁锰矿矿物学和表面化学及对砷的吸附研究

发布时间：2018-06-08 05:42

本文选题：含铁锰矿 + 重金属吸附　；参考：《华中农业大学》2017年硕士论文

【摘要】：重金属吸附材料一直是环境科学的研究重点,其中针对典型吸附材料铁氧化物、锰氧化物的研究较多。天然含铁锰矿集合了铁氧化物、锰氧化物的特性,对重金属具有很好的去除效果,且资源广泛,具有非常好的应用前景,但目前对含铁锰矿性质及对重金属去除机理的研究较少。本文以天然含铁锰矿、合成的铁氧化物、锰氧化物及铁锰二元复合氧化物作为研究对象,采用XRD、FTIR、TG、XPS、扫描电镜等技术手段对材料进行成分分析、矿物学及表面化学表征,并研究了材料对重金属(铅、锌、镉、铬、砷)的吸附效果,分析了不同因素对含铁锰矿吸附砷的影响,再结合对吸附砷前后材料的表征,探讨了含铁锰矿吸附砷的机理。主要结论如下:1.采用XRD、FTIR分析技术发现,供试10种天然含铁锰矿均含有软锰矿、磁铁矿、赤铁矿、褐铁矿,其中碳酸锰矿还含有特有物质菱铁矿和菱锰矿。通过扫描电镜观察材料形貌特征发现,天然含铁锰矿以块状形式存在为主,表面较光滑,吸附砷后有小颗粒吸附在块状表面;而合成矿物颗粒较小,排列疏松,比表面积相较于天然含铁锰矿而言要大幅增加。2.采用TG分析技术发现,10种天然含铁锰矿及人工合成的铁氧化物、锰氧化物在47℃、260℃、590℃时质量减轻幅度较大,分别造成湿存水、结晶水、结构水的损失,同时物质结构遭到破坏。而人工合成的铁锰二元复合氧化物主要在300℃之前损失质量。3.采用Tessier 5步顺序提取法分析铁、锰形态发现,天然含铁锰矿中Mn主要以可氧化态、可还原态和残渣态的形式存在,含量分布分别是18%~20%、11%~21%和59%~68%;Fe主要以残渣态的形式存在,含量约占95%,但残渣态不具备氧化As的能力。因此,含铁锰矿在对砷的吸附氧化过程中,Fe主要起吸附作用,而Mn则起到氧化作用。此外,在10种天然含铁锰矿中,Ca、As含量与铁、锰各形态含量显著相关,但与Fe、Mn含量无关。4.研究供试材料对5种重金属的吸附实验发现,10种天然含铁锰矿对Pb的吸附能力最强,平均去除率为92.17%,其次为As,平均去除率为61.60%,碳酸锰矿对As的吸附能力最弱,去除率仅有15.54%,但对Zn和Cd具有较好的吸附能力,其去除率分别为66.93%、42.62%。人工合成的铁锰二元复合氧化物对Pb、Cr、As的吸附能力都很强,平均去除率依次为97.25%、99.34%、99.98%,对Zn、Cd的吸附能力却很弱,平均去除率依次为67.61%、53.85%。人工合成的铁氧化物和锰氧化物对Pb、As的吸附量很高,对Zn、Cr、Cd的吸附量随氧化物种类不同而有较大差异,表现出选择性吸附。含铁锰矿对Cr的去除率与材料比表面积及Fe含量显著正相关,与锰的氧化度显著负相关;As去除率与材料比表面积及Fe含量显著正相关。5.采用实验室批处理实验发现,含铁锰矿材料吸附砷符合Freundlich等温吸附方程。吸附动力学分析结果表明,前4h含铁锰矿与砷溶液反应迅速,至12h时反应达到平衡。6.采用XRD、FTIR、XPS对吸附砷前后的矿物材料进行分析,结果表明,在吸附过程中,Mn作为氧化剂将As(Ⅲ)氧化成As(Ⅴ),而Mn则由Mn(Ⅳ)还原成Mn(Ⅱ),反应过程中Fe的价态并未发生变化,说明在含铁锰矿吸附As(Ⅲ)过程中Mn起到氧化还原的作用,而Fe仅参与吸附反应,促进提高含铁锰矿对As(Ⅲ)的去除。
[Abstract]:Heavy metal adsorption materials have always been the focus of environmental science. Among them, there are many studies on the typical adsorbents iron oxide and manganese oxide. The natural ferromanganese contains iron oxide, manganese oxide, and has a very good removal effect to heavy metals, and has a very good application prospect. But at present, iron and manganese containing iron and manganese are very good. The properties of ore and the mechanism of heavy metal removal are seldom studied. In this paper, the composition analysis, mineralogy and surface chemical characterization of XRD, FTIR, TG, XPS, and scanning electron microscope are used in the study of natural ferromanganese, synthetic iron oxides, manganese oxides and iron manganese two composite oxides. The effect of the adsorption of (lead, zinc, cadmium, chromium, arsenic) on the adsorption of arsenic in ferromanganese ore was analyzed. The mechanism of the adsorption of arsenic in manganese ore was discussed. The main conclusions were as follows: 1. using XRD and FTIR analysis technology, 10 kinds of natural ferromanganese ores were found to contain pyrolusite, magnetite and hematite. By scanning electron microscope, it is found that the natural ferromanganese deposits are mainly in the form of massive form, the surface is smooth, and the small particles are adsorbed on the massive surface after the adsorption of arsenic, while the synthetic ore particles are smaller and are loosely arranged and compared to the natural surface area. As for ferromanganese ore,.2. can be greatly increased by TG analysis technology, 10 kinds of natural iron containing manganese ore and synthetic iron oxide, manganese oxide at 47, 260 and 590 C, the quality is greatly reduced, resulting in the loss of wet storage water, crystalline water, loss of structure water and the destruction of the material structure, while the artificial synthetic iron and manganese compound is two. The oxide mainly lost mass.3. before 300 centigrade by Tessier 5 step sequential extraction method to analyze iron. The form of manganese in the natural iron containing manganese ore was found to be mainly oxidizable, reducible and residue, and the content distribution was 18%~20%, 11%~21% and 59%~68%, respectively, and the content of Fe was about 95% in the form of residue, but the residue was about 95%. The state does not have the ability to oxidize As. Therefore, during the adsorption and oxidation of arsenic by ferromanganese ore, Fe mainly plays an adsorption role, while Mn plays the role of oxidation. In addition, the content of Ca and As in 10 natural ferromanganese ores is significantly related to the content of iron and manganese, but the content of Fe and Mn is not related to the adsorption experiment of the 5 kinds of heavy metals by the.4. research materials. The 10 kinds of natural ferromanganese ores have the strongest adsorption capacity to Pb, the average removal rate is 92.17%, the second is As, the average removal rate is 61.60%, the adsorption ability of manganese carbonate to As is the weakest and the removal rate is only 15.54%. But the adsorption capacity of Zn and Cd is better, the removal rate is 66.93%, and 42.62%. synthetic iron manganese two compound oxide is on P. The adsorption capacity of B, Cr and As is very strong, the average removal rate is 97.25%, 99.34%, 99.98%. The adsorption capacity of Zn, Cd is very weak, the average removal rate is 67.61%. The adsorption capacity of 53.85%. synthetic iron oxide and manganese oxide on Pb, As is very high. The adsorption capacity of Zn, Cr, Cd is very different with the species of oxide, showing the choice of selection. The removal rate of Cr with ferromanganese has a significant positive correlation with the specific surface area and Fe content of the material, and a significant negative correlation with the oxidation degree of manganese; the removal rate of As and the specific surface area and Fe content of the materials are significantly positively correlated.5. using the laboratory batch experiment. The adsorption equation of the arsenic bearing Freundlich isothermal adsorption equation and the adsorption dynamic credits are found. The results show that the reaction of the former 4H iron manganese ore with the arsenic solution is rapid, and the reaction reaches the equilibrium.6. at the time of 12h. XRD, FTIR, XPS are used to analyze the mineral materials before and after the adsorption of arsenic. The results show that during the adsorption process, Mn is oxidized to As (V) as an oxidant, while Mn is reduced to Mn (II) by Mn (IV), and the valence state of the reaction does not occur during the reaction process. The result shows that Mn plays the role of redox in the process of adsorbing As (III) with ferromanganese, while Fe only participates in the adsorption reaction, which promotes the improvement of the removal of As (III) by ferromanganese.
【学位授予单位】：华中农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P579;X703

【参考文献】