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1.
在水合法制备针铁矿过程中添加H3BO3,对合成的样品作红外光谱和比表面积分析,结果表明,共沉淀法合成的样品在1343 cm-1处有特征吸收峰,说明在针铁矿形成过程中,如果有H3BO3参与,则形成的氧化铁中存在Fe—O—B键结构,可能在氧化铁内部有一种新硼铁化合物生成。比表面积测定表明,含硼氧化铁比表面积增加4倍以上,反映了氧化铁与H3BO3并非机械混合物,其表面性质因为Fe与B反应而发生改变,B阻止氧化铁向高聚合态转变。 相似文献
2.
应用Ｘ射线衍射和化学分析等手段研究了中南地区几种地带性土壤中的氧化铁类型与钼吸附的关系，结果表明：供试土壤粘粒的氧化铁以晶质氧化铁为主，非晶质氧化铁含量低，砖红壤和赤红壤中的晶质氧化铁全为针铁矿；针铁矿的平均晶粒大小一般比赤铁矿的小，而比表面积却比赤铁矿的大；针铁矿型氧化铁全为针铁矿；针铁矿的平均晶粒大小一般比赤铁矿的小，而经表面积却比赤铁矿的大；针铁矿型氧化铁的钼吸附量比针－赤混合型氧化铁的高， 相似文献
3.
负载硼的针铁矿结构表征研究 总被引：1，自引：0，他引：1
人工合成了针铁矿（Goethite）及其负载硼的氧化物（硼吸附态针铁矿Ad—B—Goethite，硼包被态针铁矿Oc—B—Goethite），用IR、X射线衍射、TEM对其进行表征，测定了它的比表面积及其对锰离子的吸附性能。IR分析表明，负载硼的针铁矿较之普通针铁矿在888cm。处的Fe—OH—Fe表面羟基弯曲振动、1000cm^-1处的表面Fe—OH弯曲振动及3100cm^-1处的游离羟基峰均减弱；硼吸附态针铁矿在458．5cm^-1处，硼包被态针铁矿在527．2cm^-1和476．5cm^-1处出现了与BO3和B（O，OH）4的弯曲振动有关的吸收峰。X射线衍射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。从TEM图上可看出硼包被态针铁矿的晶体明显要小些。实验测得3种矿物的比表面积分别是：普通针铁矿108．4m^2g^-1，吸附态针铁矿88．69m^2g^-1，包被态针铁矿120．5m^2g^-1。对锰离子的吸附量为硼包被态针铁矿明显大于硼吸附态针铁矿大于普通针铁矿。结果表明：硼包被态针铁矿（Oc—B—goethite）中B进入了针铁矿的品格，影响晶体的生长，使晶体的结晶性较差，晶体较小、比表面积增大，对锰离子的净吸附能力强。这也说明，土壤中的硼不仅起到植物营养的作用，其在形成负载硼的铁氧化物后有利于减轻土壤锰的毒害。 相似文献
4.
水稻土中铁氧化物的厌氧还原及其对微生物过程的影响 总被引：20，自引：3，他引：20
采用厌氧泥浆恒温培养实验 ,测定了添加 6种外源氧化铁后土壤中Fe(Ⅱ )和Fe(Ⅲ )浓度的变化 ,探讨了不同氧化铁的还原能力及其对土壤产H2 、产CO2 、产乙酸和产CH4 过程的影响。结果表明 :无定形氧化铁和纤铁矿易于被还原 ,两者的最终还原程度大体相同 ,但无定形氧化铁存在还原滞后现象 ;针铁矿、赤铁矿、Al取代针铁矿和Al取代赤铁矿难以被还原 ,表现出与对照相同的还原特征 ;铁还原能导致土壤中H2 和乙酸稳态浓度的降低 ,有效抑制了甲烷产生 ;添加Fe(OH) 3和纤铁矿后 ,Fe(Ⅲ )还原占总电子传递的贡献率由对照的 1 8.3 0 %增至 63 .3 2 %和 46.90 % ,而形成甲烷的电子传递贡献率由对照的 80 .92 %降至 3 5 .85 %和 5 2 .3 2 % ,Fe(Ⅲ )还原对电子的竞争消耗 ,使土壤产甲烷过程被强烈抑制 相似文献
5.
几种氧化铁的离子吸附特性研究 总被引：3，自引：1，他引：3
氧化铁是土壤中常见的氧化物,其中较为普遍的是针铁矿和赤铁矿,在某些土壤中也含有纤铁矿和无定形氧化铁.它们通常以极小的颗粒单独存在,或以胶膜状包裹在其它矿物颗粒的外面,有较大的比表面积,易受环境的影响,因此具有较高的活性,并对许多土壤的物理化学性质产生重要的影响.某些重金属离子和某些污染物进入土壤后的动向和行为也深受土壤中氧化铁的影响. 相似文献
6.
研究了针铁矿和针铁矿—胡敏酸复合体对Se(Ⅳ)的吸附机制。结果表明:针铁矿和复合体对Se(Ⅳ)的最大吸附容量分别为0.202 mmol g-1和0.159 mmol g-1。针铁矿的等温吸附数据适合用Langmuir模型拟合,而Freundlich模型更适合描述复合体的等温吸附过程。针铁矿的等电点(IEP)在7.0附近,复合体的IEP3.0;当p H=4.0时,它们的表面电位分别为46.6 m V和-40.5 m V。X—射线光电子能谱(XPS)分析显示,针铁矿和复合体表面Fe2p3/2的电子结合能(B.E.)分别为711.4e V和711.5 e V,复合体表面C1s的B.E.值为284.8 e V。初始p H=4.0时,样品与Se(Ⅳ)相互作用后的主要变化体现在:(1)针铁矿和复合体的悬浮液p H分别升高至4.4和4.2,表面电位分别降低了39.08 m V和升高了1.8 m V;(2)针铁矿表面Fe(Ⅲ)的B.E.值降低了0.4 e V,但吸附态Se(Ⅳ)的B.E.值无明显变化;(3)复合体表面Fe(Ⅲ)的B.E.值降低了0.3 e V,表面C-O中C的B.E.值由285.7 e V升高至286.5e V,吸附态Se(Ⅳ)的B.E.值升高了0.6 e V。针铁矿和复合体吸附Se(Ⅳ)的主要机制包括表面配合反应(复合体表面铁羟基与HSe O3-之间存在双齿配位)、静电引力、氢键等作用。此外,复合体表面吸附态Se(Ⅳ)同时与针铁矿和胡敏酸发生了作用,形成了针铁矿—Se(Ⅳ)—胡敏酸三元体。 相似文献
7.
本研究选取代表性层状硅酸盐蒙脱石，两种代表性氧化铁(水铁矿、针铁矿)，合成蒙脱石-水铁矿、蒙脱石-针铁矿二元复合体，通过宏观吸附以及光谱学技术探究钨(WO42-)在蒙脱石-氧化铁复合体上的吸附行为和潜在机制。结果表明：氧化铁紧密覆盖在蒙脱石表面，使表面颗粒更加细小；钨的吸附量随pH升高而降低，3种吸附剂对钨吸附量大小顺序为：蒙脱石-水铁矿>蒙脱石-针铁矿>蒙脱石；原位红外光谱实验表明，钨在蒙脱石表面主要以外圈络合物形式存在，而在蒙脱石-氧化铁复合体上形成内圈络合物(Fe-O-W)，且在低pH时，形成聚合态钨；X-射线光电子能谱进一步表明，针铁矿和水铁矿表面铁羟基参与了钨的络合反应。本研究证实，氧化铁覆盖不仅增大蒙脱石对钨的吸附量，而且使钨由外圈络合物形态转变为内圈络合态，进一步生成聚合态钨。研究结果对预测钨在土壤中的迁移转化、生物有效性和归宿有重要指导意义。 相似文献
8.
Mn~(2+)掺杂对晶质氧化铁结构与红外光谱特征的影响 总被引：1，自引：1，他引：0
制备针铁矿和赤铁矿的混合晶质氧化铁(CIO)和不同摩尔比例(R)的Mn~(2+)掺杂晶质氧化铁(CIO-Mn_x(x=0.1、0.2、0.3和0.5))样品。根据样品的X-射线衍射(XRD)和透射电镜(TEM)结果分析Mn~(2+)掺杂对晶质氧化铁结构与形貌的影响;对样品的傅里叶红外图谱(FT-IR)的高波数(3 000～3 700 cm~(–1))和低波数(450～750 cm~(–1))两个区间做分峰拟合,分析Mn~(2+)掺杂晶质氧化铁的羟基官能团和晶体结构化学键的变化特征。结果显示,R为0.1～0.3的Mn~(2+)掺杂抑制了针铁矿和赤铁矿等晶质氧化铁的形成;R为0.5的Mn~(2+)掺杂导致样品中形成了掺锰磁铁矿,且存在少量的针铁矿而没有明显的赤铁矿。CIO样品中存在自由羟基、吸附水羟基、表面缔合羟基和结构羟基共四类羟基。在R为0.1～0.3范围内,随着R的增大,样品中自由羟基和吸附水羟基的相对含量降低,而表面缔合羟基和结构羟基的相对含量增大。此外,Mn~(2+)掺杂导致样品中自由羟基和结构羟基的吸收带波数降低,而吸附水羟基和表面缔合羟基的吸收带波数随R的增大而增大。CIO样品中Fe-O振动在455 cm~(–1)和619 cm~(–1)附近红外吸收带的强度和峰形与样品中针铁矿颗粒的形貌有关,478 cm~(–1)和560 cm~(–1)附近的红外吸收与样品中赤铁矿的结晶度密切相关。分析表明,CIO-Mn_x样品中的赤铁矿结构中阳离子空位与Mn~(2+)耦合产生了567～589 cm~(–1)附近的吸收,其强度随着R的增大而增强。CIO-Mn_(0.5)样品中形成了Mn~(2+)替代Fe2+的掺锰磁铁矿,导致样品在593 cm~(–1)处出现了Mn-O晶格振动吸收带。 相似文献
9.
蒙脱石-氧化铁复合体的表征及其对不同形态磷的吸附特性 总被引：1，自引：0，他引：1
制备了蒙脱石-针铁矿复合体(Mt-Goe)和蒙脱石-非/弱晶质氧化铁复合体(Mt-HFO),研究了它们的结构、表面性质及其对无机磷酸盐(Pi)和植酸(IHP)的吸附特性。结果显示,Mt-Goe中少量羟基铁离子进入了蒙脱石晶层间导致其层间距增大,针铁矿颗粒较好地包被在蒙脱石外表面;Mt-HFO中蒙脱石层间则发生了Fe~(3+)水解,生成了(羟基)铁氧化物,并在蒙脱石表面形成非晶质氧化铁颗粒。蒙脱石、Mt-Goe和Mt-HFO的比表面积分别为258.7、185.4和226.4 m~2·g~(–1),其表面分形度、等电点和表面羟基含量均依次升高,pH5.5时的表面Zeta电位分别为–46.1、–13.6和–19.4 mV。3种样品对Pi和IHP的吸附模式以匀质性表面单层吸附为主,Langmuir饱和吸附量(qmax)和吸附亲和力均表现为由大到小依次为Mt-HFO、Mt-Goe、蒙脱石。3种样品对Pi和IHP的动力学吸附过程适合用准二级动力学模型描述,其速率常数由小到大依次为Mt-HFO、Mt-Goe、蒙脱石。与吸附Pi相比,3种样品吸附IHP的动力学速率常数明显减小,吸附量明显增大;Mt-HFO对IHP的吸附速率尤其缓慢,而吸附量远大于对Pi的吸附量。 相似文献
10.
Fe(Ⅱ)存在条件下氧化铁-高岭石复合物的形成与转化 总被引：3，自引：1，他引：2
氧化铁-高岭石复合物是我国南方土壤的重要组分,也是影响这些土壤理化性质的主要因子。本文以Fe(Ⅱ)为添加剂,研究了晶质氧化铁-高岭石复合物的形成与转化过程及其影响因素。结果表明,Fe(Ⅱ)可加速晶质氧化铁-高岭石复合物的形成,在一定程度上克服了高岭石对晶质氧化铁形成的抑制作用。当Fe(Ⅱ)/Fe(Ⅲ)摩尔比(R)在0.04~0.06时,Fe(Ⅱ)可加速纤铁矿、针铁矿、赤铁矿-高岭石复合物的形成;当R≥0.1时,可快速形成磁铁矿-高岭石复合物。在温度50~60℃、pH5~6条件下,Fe(Ⅱ)可加速纤铁矿、针铁矿-高岭石复合物的形成;温度80℃及中性附近时,可加速赤铁矿-高岭石复合物的形成;pH9时,则形成了磁铁矿-高岭石复合物。高岭石的存在减弱了Fe(Ⅱ)对晶质氧化铁形成的催化效果,也可影响产物类型和结晶形貌。上述结果可为自然环境中氧化铁以及氧化铁-高岭石复合物的形成转化过程提供重要参考。 相似文献
11.
The sorption of inorganic phosphate (P) by soils and hydrous ferric oxides was studied at times up to 192h. An initially rapid decrease in solution P concentration was followed by a much slower decrease between 48 and 192h with soils, Fe gel. and natural goethite, whereas synthetic goethite gave a well-defined equilibrium condition after only 48h. Resolution of the sorption isotherms showed that the increase in P sorption with time involved an appreciable shift of P from a more-physically sorbed form to a chemisorbed form. This was supported by chemical fractionation which showed that NaOH-extractable P was fairly constant with increasing sorption time, whereas the additional sorbed P was extracted by citrate-dithionite-bicarbonate from soils, and by HC1 from Fe gel and natural goethite. These sorbents contained short-range (amorphous) material, whereas synthetic goethite, from which all sorbed P was NaOH –extractable. did not. It is proposed that the time-dependent sorption of P and the associated shift of P to chemisorbed forms, involves the diffusion of P into “structurally porous”, short-range order material. 相似文献
12.
Rusty ferruginous precipitates deposited from soil-borne waters (in drainage ditches, from springs) at various localities, contain a ferric hydroxide rich in carbon and adsorbed water. It has up to 75% dithionite soluble Fe2O3, of which between 90 and 100% is oxalate soluble IR spectrograms do not show Fe-OH features in the OH stretching and bending range. X-ray diffraction reveals very broad lines at about 2.5 and 1.5 Å and somewhat sharper lines at 2.22, 1.97 and 1.71 Å, which are characteristic of ferrihydrite (name proposed by Chukhrov et al., 1972). These deposits are found in areas where water has percolated through acid soils rich in low molecular weight organic compounds. Furthermore, as similar material could be prepared in the laboratory by bacterial or H2O2 oxidation of ferric citrate solutions, it was concluded that the natural substance is formed by microbial decomposition of soluble iron—organic complexes. Transformation experiments suggest that aging under conditions corresponding to a humid temperate climate causes conversion to goethite. This aging process is greatly retarded by organic and other compounds retained by the hydroxide. No evidence of hematite formation could be found after 2 weeks at 70°C. 相似文献
13.
应用穆斯堡尔谱和X射线法研究红壤性水稻土的氧化铁矿物 总被引：1，自引：1，他引：1
应用穆斯堡尔谱和X射线法分析研究红壤性水稻土的氧化铁矿物,研究结果表明,红壤性水稻土的氧化铁矿物组成、特性及其形成转化与起源土壤具有明显的差异。水稻土的成土条件不利于赤铁矿的形成。红壤的粘粒氧化铁矿物以赤铁矿和高铝替代(>20摩尔%)的针铁矿为主。经淹水种稻后,赤铁矿逐渐被转化为低铝替代的针铁矿或其它形态氧化铁。渗育型水稻土P层的赤铁矿含量比相应的母土低,其针铁矿铝替代量较其它水型的水稻土高。而潴育型水稻土W层和潜育型水稻土G层粘粒氧化铁矿物均以针铁矿为主,其铝同晶替代量低(<15摩尔%),且颗粒细小,结晶度较低。这些结果反映了水稻土的成土条件和发生特点,同时对水稻土发生分类具有重要的意义。 相似文献
14.
The iron oxide and clay minerals in some typical red and yellow podzolic soils from New South Wales have been investigated by X-ray diffraction and infra-red spectroscopy. The dominant iron oxide mineral is goethite containing about 13–14 mol % AlOOH, this being the mineral which gives the yellow soils their characteristic colour. The red soils also contain finely divided hematite which masks the colour of the goethite. Lepidocrocite was not detected in any of the soils examined. The dominant clay minerals are kaolinite and dioctahedral interstratified illite-smectite, the latter being more concentrated in the finer clay fractions, especially in soils developed on calcareous greywacke. In the red podzolic soil developed on Ashfield shale, illite-smectite is strongly interlayered with well-ordered aluminous material. Dickite occurs in this soil. 相似文献
15.
A soil toposequence in NE Italy was studied, which consists of a terra rossa on Cretaceous limestone on the upper slope grading downwards into a colluvial fan with terra rossa material and finally into alluvial river sediments. It is postulated that the red colluviated terra rossa material has come under a moister hydroregime which provided reducing conditions. Because hematite of the terra rossa dissolved preferentially over goethite, as shown by quantitative Fe oxide mineralogy, soil color changed from 2.5YR to 7.5YR. The soils contained two types of concretions, red ones with a low Feo/Fed ratio and a high content of hematite and low content of Mn-oxides and black ones with a high Feo/Fed ratio, a small amount of hematite and abundant Mn oxides. The red concretions are therefore considered as inherited from an earlier period of pedogenesis whereas the black ones are neoformed in the present pedoenvironment. This is further supported by the lower Al-for-Fe substitution of goethite in the black concretions as compared to a higher Al substitution in the goethite inherited from the terra rossa. 相似文献
16.
Microbial ferric iron reduction, with organic carbon or hydrogen as the electron donor, is one of the most important biogeochemical processes in anoxic paddy soils; however, the diversity and community structure of hydrogen-dependent dissimilatory iron-reducers remain unknown. Potential H2-dependent Fe(III)-reducing bacteria in paddy soils were explored using enrichment cultures with ferrihydrite or goethite as the electron acceptor and hydrogen as the electron donor. Terminal restriction fragment length polymorphism (T-RFLP) analysis and cloning/sequencing were conducted to reveal bacterial community structure. Results showed that Geobacter and Clostridium were the dominant bacteria in the enrichment cultures. Fe(III) oxide mineral phases showed a strong effect on the community structure; Geobacter and Clostridium were dominant in the ferrihydrite treatment, while Clostridium spp. were dominant in the goethite treatment. These suggested that H2-dependent Fe(III)-reducing bacteria might be widely distributed in paddy soils and that besides Geobacter, Clostridium spp. might also be an important group of H2-dependent Fe(III)-reducing microorganisms. 相似文献
17.
Transformation of poorly-crystalline oxides during boiling with NaOH to concentrate iron oxides from soils 总被引：2，自引：0，他引：2
The effect of boiling 5 M NaOH on the nature of poorly crystalline iron oxides in some iron pans from Scottish soils has been investigated by IR and Mössbauer spectroscopy in conjunction with XRD. In samples that contained goethite and other crystalline oxides there was substantial production of goethite from the less well-defined phases as a result of the alkali treatment. Neither kaolinite nor humic acid, when added to the samples, was effective in preventing this transformation, although some inhibition was observed. There was, however, no goethite production with a pan that had no crystalline iron oxides, although this could be stimulated by the addition of small amounts of either goethite or haematite. The practice of using the boiling alkali method routinely for the concentration of crystalline iron oxides in soils should, therefore, be considered carefully, since any co-existing crystalline and non-crystalline phases are likely to lead to the transformation of the latter to goethite. 相似文献
18.
Essentially congruent dissolution of colloidal ferric phosphate, metastrengite, and strengite was observed at pH 1.5 during 25 days. In contrast, preferential release of P to solution was obtained at pH 6.0. Dialysis of dried preparations of these three materials against hydrous ferric oxide gel (Fe gel) resulted in the loss of 9.0, 3.0, and 0.4 per cent of total P, respectively, during 20 days. A wet preparation of colloidal ferric phosphate released 17 per cent of total P during the same time. During dialysis, all ferric phosphates assumed a brownish colour. Electron microscopy revealed the presence of an appreciable quantity of short-range order material surrounding crystals of strengite following dialysis. These observations, coupled with the decrease in type ratio, demonstrate that an Fe gel coating forms on the ferric phosphates during dialysis. The results are discussed in terms of the likely stability of ferric phosphates in soils. 相似文献
19.
HU GUO-SONG 《土壤圈》1994,4(2):153-164
The study results of the effects of temperature and ionic strength on the adsorption kinetics of Pb2+ and Cu2+ by latosol, red soil and kaolinite coated with Mn oxide showed that Pbr" and Cur" adsorption by all samples, as a whole, increased with raising temperature. Temperature also increased both values of Xm (the amount of ion adsorbed at equilibrium) and k (kinetics constant) of Pb2+ and Cu2+ The activation energies of Pb2+ adsorption were kaolin-Mn>red soil>goethite and those of Cu2+ were latosol>red soil>kaolin-Mn>goethite. For a given single sample the activation energy of Cu2+ was greater than that of Pb2+. Raising ionic strength decreased the adsorption of Pb2+ and Cu2+ by latosol, red soil and kaolinite coated with Mn oxide but increased Pb2+ and Cu2+ adsorption by goethite. The contrary results could be explained by the different changes in ion forms of Pb2+ or Cu2+ and in surface charge characteristics of latosol, red soil, kaolin-Mn and goethite. Increasiclg supporting electrolyte concentration in-creased Xm and k in goethite systems but decreased and k in kaolin-Mn systems. All the timedependent data fitted the surface secondorder equation very well.] 相似文献
20.
浙江省三种红、紫色砂页岩发育土壤的矿物学研究 总被引：6，自引：1，他引：5
本文用Ｘ射线衍射分析,红外光谱分析、透射电镜及Ｘ射线荧光分析对浙江省三种红、紫色砂页岩发育的红砂土、紫砂土和红紫砂土的矿物进行了分析。 相似文献