【作者】 廖水姣；

【导师】 朱端卫；

【作者基本信息】 华中农业大学 ， 植物营养学， 2009， 博士

【摘要】 本文以人工合成针铁矿（Goethite简写为G）和铝氧化物（Al hydroxide）为对照,以其含硼负载体为研究对象,其中,人工合成针铁矿经硼砂溶液吸附处理后称为硼吸附态针铁矿（Goethite adsorbed boron简写为ad-B-Goethite或ad-B-G）,针铁矿和铝氧化物在合成过程中加入硼酸经沉淀后得到的硼负载体分别称硼包被态针铁矿（Goethite occluded boron简写为oc-B-Goethite或oc-B-G）和硼包被态铝氧化物（Aluminium hydroxide occluded boron简写为oc-B-Al hydroxide）,探讨其化学组成、晶体结构形貌、光学和电学等性能;研究普通针铁矿及其两种硼负载体对铝离子的吸附特性,铝氧化物及硼包被态负载体对锰离子的吸附特点,以及针铁矿及其含硼负载体对苯胺的吸附降解特性,主要研究结果如下:1)瓜光谱中,硼负载体针铁矿较之普通针铁矿,Fe-OH-Fe表面羟基弯曲振动、表面Fe-OH弯曲振动及游离羟基峰均减弱,且硼吸附态针铁矿和硼包被态针铁矿出现了与BO₃和B（O,OH）₄的弯曲振动有关的吸收峰。2) X-射线衍射谱分析表明,硼吸附态针铁矿的晶形与普通针铁矿相似,而硼包被态针铁矿的衍射吸收峰的位置、个数和相对强度都发生了变化;XPS表征发现,B负载在针铁矿中引起矿物的O_1S、Fe_3S、Fe_3p、Fe_2p的XPS精细谱发生变化;TEM照片及比表面积的数据说明在合成针铁矿中加入硼会影响晶体的生长,晶体的结晶性较差,晶体较小,均支持在硼包被态针铁矿中,硼进入了针铁矿晶格的假设。3)针铁矿、硼吸附态针铁矿和硼包被态针铁矿对Al³⁺的等温吸附属于单分子层吸附,吸附反应的吸附热分别是:27.56 KJ/mol、23.18 kJ/mol和49.93 kJ/mol。随着溶液pH逐渐升高,G、ad-B-G和oc-B-G等3种铁氧化物吸附Al³⁺离子的吸附量增加速率呈现先快后慢的趋势。在相同条件下,硼包被态针铁矿对铝的吸附量和吸附后体系的pH均明显大于硼吸附态针铁矿和普通针铁矿,说明硼包被态针铁矿能吸附更多的铝,如果将其应用到酸性土壤,可以缓解土壤酸化。4)铁氧化物对苯胺存在专性吸附,吸附主要是单分子层的吸附,符合Langmuir方程,负载硼的针铁矿对苯胺的吸附量大于普通针铁矿。可见光/铁氧化物体系中苯胺降解反应能用一级动力学方程很好地拟合,铁氧化物可见光催化降解苯胺的活性的顺序为:硼包被态针铁矿＞硼吸附态针铁矿＞普通针铁矿;升高温度或增大苯胺的浓度均有利于苯胺的降解;降解在pH为5左右效果最好。苯胺在可见光/H₂O₂/铁氧化物体系中降解大于其在可见光/铁氧化物体系中的降解。紫外光/铁氧化物体系中苯胺降解具有一级反应动力学特征;相同条件下其降解能力的顺序是:硼包被态针铁矿＞普通针铁矿＞硼吸附态针铁矿;苯胺紫外光降解的中间产物主要有偶氮苯、硝基苯、4-硝基-6-醛基己酸和氨基酚。5)本研究合成的铝氧化物是弱晶质的一水软铝石,负载硼的铝氧化物无序化程度更高。TEM照片显示,前者是纤维状团聚合体,后者是球状团聚合体。TEM和XRD都证实了负载硼的氧化物粒子较小。负载硼的铝氧化物的比表面积较普通铝氧化物的大。负载硼的铝氧化物中表面Al-OH的IR吸收峰(1074cm^-1)变弱,说明硼酸根与铝氧化物的表面Al-OH发生了反应。XPS定量分析可知,负载硼的铝氧化物表面原子Al:O:B的个数比为29.56:66.9:3.45,有少量的B进入了铝氧化物晶格中。负载硼的铝氧化物比普通的铝氧化物能吸附更多的锰离子,土壤中若存在负载硼的铝氧化物可以减少植物锰毒,缓解土壤酸化。更多还原

【Abstract】 Goethite（G）, Al hydroxide, Goethite adsorbed boron （ad-B-Goethite or ad-B-G）, Goethite occluded boron（oc-B-Goethite or oc-B-G） and Aluminium hydroxide occluded boron（oc-B-Al hydroxide） were synthesized. ad-B-G was prepared by adsorption of the original goethite to B in borax solution, oc-B-G and oc-B-Al hydroxide were prepared in the presence of boric acid solution by hydrolyzation. Composition, morphology, structure and properties of goethite and Al hydroxide doped with boron were discussed; Al³⁺ adsorption on goethite and goethite doped with boron, Mn²⁺ adsorption on Al hydroxide and oc-B-Al hydroxide, and adsorption and degradation of aniline on goethite and goethite doped with boron were studied. The main results for the study were:1) The IR bands of Fe-OH-Fe, Fe-OH in-plane bending, and the IR bands of free OH of ad-B-goethite and oc-B-goethite were weaker than those of the original goethite. The IR bands of bending modes of trigonal and tetrahedral B were found in oc-B-goethite and ad-B-goethite. The results suggested that boron in boron-doped goethites replaced some free OH groups of the original goethite.2) Analysis of XRD patterns indicated ad-B-goethite remained the characteristic ofα-FeOOH, while oc-B-goethite did not. XPS region spectrum of O_1S, Fe_3S, Fe_3p and Fe_2P of ad-B-goethite, oc-B-goethite were different with goethite for boron doping. Judging by TEM graphs, the particle of oc-B-goethite was smaller than that of goethite. The specific surface area of goethite, ad-B-goethite and oc-B-goethite was in the order of oc-B-goethite>goethite>ad-B-goethite. All those support the hypothesis that ad-B-goethite remainedα-FeOOH, however, oc-B-goethite may be a different mineral.3) The isotherms of Al³⁺ adsorbed by goethite and goethite doped with boron at 15℃and 25℃were in good agreement with Langmuir equation, Al³⁺ adsorptive reactions were endothermic and the enthalpy of Al³⁺ sorption on goethite, ad-B-goethite and oc-B-goethite were 27.56 kJ/mol, 23.18 kJ/mol and 49.93 kJ/mol, respectively. Al³⁺ adsorption amount of the original goethite and boron-doped goethites all increased with pH, boron-doped goethites always adsorbed more Al³⁺ than the original goethite at the same pH solution. Therefore, boron-doped goethites should be helpful in reducing the toxicity of Al³⁺ in acidic soil.4) The isotherms of aniline on goethite and goethite doped with boron at 25℃were in good agreement with Langmuir equation, aniline adsorption amount of the original goethite, ad-B-goethite and boron-doped goethites was in the order of oc-B-goethite> goethite> ad-B-goethite. Aniline degradation was fast under higher temperature and higher aniline concentration, it was very fit for H-L equation in visible light/iron oxides and it had highest degradation effect about pH=5. The catalysis on aniline degradation was in the order of oc-B-goethite> ad-B- goethite> goethite. Aniline degradation prefer visible light /H₂O₂/ iron oxides to visible light/ iron oxides. Aniline degradation was fit for H-L equation in UV/iron oxides excellently. The catalysis on aniline degradation was in the order of oc-B-goethite> goethite> ad-B-goethite. Nitrobenzene, azobenzene, 4-nitro-6-formaldehydel-hexanoic acid and aminophenol were main intermediates of degradation of aniline.5) Analysis of XRD patterns indicated that oc-B-Al hydroxide was more poorly crystalline boehmite than the Al hydroxide. TEM observation showed that the Al hydroxide and oc-B-Al hydroxide had different morphology. Analysis of TEM and XRD all demonstrated that the presence of boron significantly decreased the size of Al hydroxide particles. The specific surface area of oc-B-Al hydroxide using BET method was larger than that of Al hydroxide. The IR band of Al-OH at 1074 cm^-1 of oc-B-Al hydroxide was weaker than that of Al hydroxide. The results suggested that boron in boron-doped Al hydroxide replaced some free OH groups of the Al hydroxide. The qualification of the peak intensities by XPS revealed that the surface atomic ratio of Al : O : B of oc-B-Al hydroxide was 29.56 : 66.9 : 3.45. Curve-fitted B（ls） XPS spectrum of oc-B-Al hydroxide demonstrated that the boron atom was probably incorporated with Al hydroxide to some extent. Oc-B-Al hydroxide always adsorbed more Mn²⁺ and stabilized the sample solution pH to a higher value than Al hydroxide, therefore, oc-B-Al hydroxide should be helpful in reducing the toxicity of Mn²⁺ in acidic soil and slow soil acidification.更多还原