温度对煤吸附甲烷的影响实验

为了研究温度对煤吸附甲烷的影响,实验测定了不同温度下煤对甲烷的吸附等温线,并对实验数据进行了拟合,同时对覆盖度与压力、温度、吸附量以及孔隙类型的关系进行了分析。结果表明:随着温度的增高,饱和吸附量和吸附速率明显降低,并且含气量与覆盖度呈正相关关系;同一压力下,随着温度升高,覆盖度降低;相对覆盖度概念可以解释高温覆盖度高而吸附量小于低温阶段的现象;结合孔隙度和液氮分析结果发现,随着温度的增高,小孔和微孔的吸附能力强于中孔和大孔;甲烷在煤上的等量吸附热随吸附量的增大而增大,但无规律可循,且由Clausius-Clapeyron方程预测出的等温吸附曲线与实测值有偏差,表明煤表面能量的不均匀性和表面离子的复杂性。      

多粘芽孢杆菌(Paenibacillus polymyxa)吸附Cu2+的实验研究

细菌表面往往存在多种化学基团,能够通过吸附作用影响环境流体中金属元素的活动性,从而与表生条件下的元素富集、矿物成核结晶等地球化学过程密不可分。为了深入认识细菌吸附作用的地球化学意义和环境效应,揭示细菌吸附金属离子的热力学行为,选择了多粘芽孢杆菌(Paenibacillus polymyxa)为研究细菌,系统开展了滴定实验和Cu2 吸附实验。通过连续酸滴定方法分析了细菌表面的化学特征,发现多粘芽孢杆菌在pH值为7.54~6.50范围内,表面带负电荷,表现出质子吸附行为;设计开展了Cu2 吸附实验,发现溶液的pH值对Cu2 吸附有一定影响,可能存在Cu2 与细菌表面质子的交换作用;根据Cu2 吸附等温线拟合计算,发现吸附等温线符合Langmuir和Freundlich吸附模型,根据Langmuir模型计算得到每个细胞的Cu2 饱和吸附量高达1.69×10-7mg。     

施氏矿物吸附Cu2+及氧化亚铁硫杆菌的实验研究

在金属硫化物的表生氧化过程中,施氏矿物是最常见的一种次生矿物.施氏矿物具有粒度小、比表面积大、表面吸附能高的特点,能够吸附环境流体中的重金属离子和微生物细胞,从而影响重金属元素及微生物的表生地球化学行为.利用化学合成的施氏矿物,开展了施氏矿物吸附Cu2+及氧化亚铁硫杆菌的实验.结果显示:施氏矿物对金属Cu2+及氧化亚铁硫杆菌均有较强的吸附性;施氏矿物对Cu2+的吸附基本符合Langmuir吸附模型,而对氧化亚铁硫的吸附行为不符合Langmuir模型,可用Freundlich模型描述;施氏矿物的存在对流体中微生物的活动性及其地球化学行为有重要影响,可能会降低氧化菌分解金属硫化物的效率.     

重金属离子在胡敏酸-高岭石复合体上的吸附

本文研究了胡敏酸存在下高岭石对重金属离子的吸附行为。实验结果表明:①胡敏酸和Cu2 溶液按先后顺序或同时加入高岭石中反应,在Cu2 平衡浓度<10mg/L时,3种加入顺序对Cu2 的吸附量基本相同,当Cu2 平衡浓度>10mg/L时,(K Cu) HA和(K Cu HA)两种加入顺序对Cu2 的吸附量比(K HA) Cu的略大。②在pH=5时,胡敏酸-高岭石复合体对Cu2 的吸附量明显大于纯高岭石。这是由于胡敏酸含有大量的羧基和酚羟基等活性基团,吸附在高岭石上的胡敏酸增加了其表面吸附位,在复合体表面形成了S—HA—Cu三元配合物,且Cu2 的吸附量与复合体中胡敏酸的含量在一定范围内成正相关;③溶液pH值在4～7之间变化可调控复合体对Cu2 的吸附机制。④在Cu2 和Cd2 共存时,随着金属离子初始浓度的增大,Cu2 的吸附量呈直线上升,而Cd2 的吸附量增加缓慢,表明复合体对Cu2 的吸附能力比对Cd2 强。     

电气石吸附Cu2+,As(Ⅲ),F-影响因素及机理研究

以新疆电气石为原料,通过原子荧光光谱仪、原子吸收分光光度研究电气石的不同粒度、用量、吸附时间、热处理温度等对水中Cu2 ,As(Ⅲ)吸附的影响;进而探讨分析电气石的吸附机理。研究结果表明:(1)电气石对Cu2 ,As(Ⅲ),F-离子的去除率随着电气石粒径的减小而增加。随着电气石用量的增加,去除率逐渐提高,增至一定值后下降。热处理温度为300℃,500℃时,可提高电气石吸附Cu2 ,As(Ⅲ)的效率。加热预处理未改善电气石对F-离子吸附能力。(2)电气石对带电性质不同的阴、阳离子都具有较好的吸附作用。电气石的极性和表面性质使其对离子可能存在络合吸附和静电吸附两种形式。电气石对Cu2 ,As(Ⅲ)吸附为表面络合吸附与静电吸附共同作用,吸附效果好。对F-吸附只存在静电吸附,吸附效果差。     

页岩油在纳米级狭缝中吸附特征的分子动力学模拟

利用分子动力学模拟方法研究了页岩油在纳米级有机质狭缝内和二氧化硅矿物狭缝内的吸附特征。在COMPASS(condensed-phase optimized molecular potential for atomistic simulation study)力场下模拟了355K、18 MPa(松辽盆地青山口组Ro=0.9%时的地质条件)条件下,混合烃类分子在纳米级狭缝内的吸附行为,对比了有机质和矿物的吸附能力以论证前人的研究,证明了模拟的正确性;分析了混合烃、各烃组分在二氧化硅狭缝和有机质狭缝中的密度分布特征及温度对有机质狭缝内烃分子吸附的影响。结果表明:(1)混合烃类分子在纳米级狭缝壁面处出现了3个较明显的吸附层,每个吸附层的厚度在0.4~0.5nm之间,且石墨烯单位面积的吸附能力约为石英的1.31倍;(2)由于竞争吸附作用,并非所有的烃类都在靠近固体壁面处吸附最多,那些容易扩散的气态烃和拥有特殊化学键的芳香烃更容易吸附在狭缝壁面处;(3)温度升高,使狭缝内混合烃类分子吸附相密度降低,但由于多组分竞争吸附作用的存在,并不是所有烷烃的密度峰值随着温度的升高而降低,5种混合烃类分子中的正构烷烃和支链烷烃的第1吸附层的密度峰值有所升高。     

高岭石水溶液的界面反应特征

高岭石的表面荷电性、溶解及其对 Cu2 、 Pb2 的吸附等实验结果表明, 高岭石的零净质子电荷点 pHPZNPC=5.2,但端面 >AlOH的 pHPZNPC在 6.5～ 7.0之间,而 >SiOH的 pHPZNPC < 2.3;然而,在 pH 2～ 10范围,ζ电位均为负值,即电动电荷等于零对应的 pH (pHIEP) < 2;且在 pH < 4溶解时, Al溶出率比 Si高,表明高岭石表层形成富 Si贫 Al层.随着溶液 pH由酸性往碱性的变化,重金属离子的吸附表现为离子交换与表面配位模式并存,并发生规律性的变化:在 pH < 6.5时主要表现为离子交换吸附,在 pH < 4时由于受到高岭石 Al的高溶出及较高的离子强度影响,高岭石对 Cu2 、 Pb2 的吸附率较低,但在 pH 5～ 6附近吸附率有明显的提升,并且有个吸附平台;在 pH > 6.5时,主要表现为离子交换和表面配位均为重要的吸附机制,若 pH再升高或重金属离子浓度过高时甚至发生表面沉淀.研究还表明,溶液 pH与离子强度影响高岭石水界面反应过程,表面溶解与质子化反应改变高岭石的表面性质,包括表面荷电性和表面位化合形态,因而调控 Cu2 、 Pb2 的界面吸附行为.     

面包酵母菌吸附黄铜矿微生物浸出矿液中Cu~(2+)的试验研究

选用面包酵母菌为吸附菌株,研究了菌株吸附黄铜矿微生物浸出矿液中Cu2+的吸附富集过程,探讨了吸附试验中pH值、温度和初始菌体加入量对Cu2+吸附效果的影响。结果表明:在酵母菌吸附Cu2+的过程中,菌体细胞上的蛋白质酰胺和多糖等成分更多地参与了吸附Cu2+的过程,Cu2+与菌体表面的有机基团结合形成颗粒物沉淀附着在细胞壁上。菌株动力学吸附分析中发现,实验用各菌株对Cu2+的动力学吸附过程除了受菌株种属的影响外,还应与菌株的细胞壁形貌、菌株本身的生长状况的等因素相关。在pH=4.5、t=30℃、初始菌体加入量8.0 g/L的条件下,吸附反应14 h后酵母菌的最佳铜吸附率可达66.64%,面包酵母菌可以吸附富集黄铜矿微生物浸出矿液中的Cu2+,可以有效回收低品位黄铜矿中的铜资源。     

蒙脱石及其热改性产物对间二硝基苯的吸附性能对比

在不同的温度条件下,制备了几种热处理蒙脱石样品,并对这些材料进行了结构与表面性质的表征,采用批吸附实验方法开展蒙脱石及其热活化产物样品对间二硝基苯(m-DNB)的吸附性能对比研究。结果表明,随着热处理温度的升高,蒙脱石层间距(d_(001))因层间结合水甚至结构水脱去而减小至0.98 nm,接近理论值,热处理温度在650℃以下时,同时吸附效果也呈现逐渐增强。适宜的K~+浓度条件下,EDA(电子供体-受体)和K~+-NO_2(阳离子-极性)两种作用效应均能够得到强化。650℃以上时,吸附效果没有得到增强,反而更差。Langmuir较之Freundlich模型能更好的拟合上述吸附过程。而且,蒙脱石及其热改性产物对m-DNB的吸附是一个放热反应,吸附反应为自发过程。     

铜(Ⅱ)在高岭石表面的吸附

在天然水体系中,铜、铅、镉等重金属元素的形态分布、迁移、归宿和生物有效性强烈取决于重金属元素在水体颗粒物表面的分配趋势.本文对铜(Ⅱ)在常见的重要粘土矿物--高岭石表面的吸附进行了实验和模式研究,结果表明,在同时考虑自由水合离子CU2+和羟基金属离子CuOH+与高岭石表面络合的情况下,单一表面基团、无静电表面络合模式能很好地描述铜(Ⅱ)的吸附行为.拟合得到的CuoH+的络合常数比Cu2+的大得多. 铜(Ⅱ)在高岭石表面的吸附量随pH值的升高而增加.吸附铜的两种表面化合态,>SOCu+和>SOCuOH的浓度在实验的pH范围内,也随pH值升高而增加,并且以>SOCu+为主.     

Studies on the flotation of sulphides. I. The effect of Cu(II) ions on the flotation of zinc sulphide

The effect of Cu(II) ions on the froth flotation of ZnS in the absence of any collector has been studied in a Fuerstenau microflotation cell. The flotation of pure synthetic ZnS, in both cubic and hexagonal modifications, can be greatly enhanced by the adsorption of traces of Cu(II) ions. In the case of cubic ZnS, the “activating” effect of Cu(II): (a) involves the stoichiometric replacement of one Zn(II) ion in the lattice by one Cu(II) ion from solution at a rate which is independent of pH (1–5); (b) is noticeable at coverages corresponding to as little as 0.1% of a monolayer, reaches a maximum at coverages of 2–100% of a monolayer, and decreases again at higher coverages; (c) is unaffected by the presence or absence of O₂, by variation of the pH of flotation (6–10), by heating in vacuum at 250°C for two hours or by storing in the dry state for over one year; and (d) does not appear to involve any significant change in surface area or in the state of aggregation of the particles.     

An attempt to use LA-ICP-SMS to quantify enrichment of trace elements on pyrite surfaces in oxidizing mine tailings

Metals released from oxidation and weathering of sulphide minerals in mine tailings are to a high degree retained at deeper levels within the tailings themselves. To be able to predict what could happen in the future with these secondarily retained metals, it is important to understand the retention mechanisms. In this study an attempt to use laser ablation high-resolution ICP-MS (LA-ICP-SMS) to quantify enrichment of trace elements on pyrite surfaces in mine tailings was performed. Pyrite grains were collected from a profile through the pyrite-rich tailings at the Kristineberg mine in northern Sweden. At each spot hit by the laser, the surface layer was analyzed in the first shot, and a second shot on the same spot gave the chemical composition of the pyrite immediately below. The crater diameter for a laser shot was known, and by estimating the crater depth and total pyrite surface, the total enrichment on pyrite grains was calculated. Results are presented for As, Cd, Co, Cu, Ni and Zn. The results clearly show that there was an enrichment of As, Cd, Cu and Zn on the pyrite surfaces below the oxidation front in the tailings, but not of Co and Ni. Arsenic was also enriched on the pyrite grains that survived in the oxidized zone. Copper has been enriched on pyrite surfaces in unoxidized tailings in the largest amount, followed by Zn and As. However, only 1.4 to 3.1% of the Cd and Zn released by sulphide oxidation in the oxidized zone have been enriched on the pyrite surfaces in the unoxidized tailings, but for As and Cu corresponding figures are about 64 and 43%, respectively. There were many uncertainties in these calculations, and the results shall not be taken too literally but allowed the conclusion that enrichment on pyrite surfaces is an important process for retention of As and Cu below the oxidation front in pyrite rich tailings. Laser ablation is not a surface analysis technique, but more of a thin layer method, and gives no information on the type of processes resulting in enrichment on the pyrite surfaces. Although only pyrite grains that appeared to be fresh and without surface coatings were used in this study, the possibility that a thin layer of Fe-hydroxides occurred must be considered. Both adsorption to the pyrite directly or to Fe-oxyhydroxides may explain the enrichment of As, Cd, Cu and Zn on the pyrite surfaces, and, in the case of Cu, also the replacement of Fe(II) by Cu(II) in pyrite.     

Protective mineral layers formed from granite–dry steam interaction

This work focuses on interaction between granite–stainless steel (SUS) pipe–dry steam in the presence of Cu. Three types of hydrothermal experiments were conducted: (1) SUS–Cu–granite, (2) SUS–Cu, (3) SUS–granite. It was found that a high protective amorphous AlSi_1,6O₄ layer (thickness about 5 μm) was formed on the supporting pipe surface only in the case of SUS–Cu–granite interaction. The Al silicate layer formed during the experiment was characterized by X-ray diffraction (XRD) techniques and scanning electron microscopy (SEM) with EDX. According to kinetic data this layer has high protective properties.     

Analyses of trace elements on quartz surfaces in sulfidic mine tailings from Kristineberg (Sweden) a few years after remediation

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been applied to determine the elemental composition of the surface layer, as well as of the first interior layer, of quartz grains from the mine tailings from Kristineberg (northern Sweden) in order to determine concentration gradients between these two layers. The quartz grains were collected from the oxidized and unoxidized zones within the tailings. The aim of this study is to assess the role of quartz surfaces as sites for the attenuation of solutes from the mine-tailings porewater. Concentrations of Cu, Ag, Sb, Pb and Bi are highest near the surface of each grain and decrease towards the interior. The surface concentration of Cu, Zn and Pb is more pronounced within the unoxidized than within the oxidized zone of the tailings. Cu exhibits a distinct concentration peak at the surface of the quartz grains below the pre-remediation oxidation front. For Zn and Ce the trend of high surface concentration is less pronounced than for Cu or Pb. Silver, Bi and As are preferably adsorbed within the uppermost layers of the oxidized zone where the pH is as high as 6.2. The conversion of intensity signals of the elements to concentration values in ppm was done by using external standards (NIST silicate glass).     

安徽铜陵水木冲尾矿重金属赋存状态及污染特征研究

为探讨富硫化物尾矿酸化及重金属污染特征,选择安徽铜陵水木冲尾矿库浅层(0～90 cm)剖面为研究对象,对其结构特点、矿物组成、重金属(Pb、Cd、Zn、Ni、Cr、Mn、Cu和As)含量及赋存形态进行研究。结果表明,该尾矿库浅层出现分层现象,即表层为强硬化层,向下依次为弱硬化层和松散层,且呈酸性;矿物主要以辉石、长石、云母和石膏为主,由浅及深,金属硫化物及碳酸盐型矿物特征峰呈现增强的趋势;重金属呈现两种富集类型:表层(0～30cm,As、Pb)富集和中部(40～60 cm,Cd、Cu、Mn、Ni、Zn和Cr)富集型,其中Cu、Cd、As污染较为严重。由相关性分析可知,部分金属之间存在一定的伴生性,且p H值是影响重金属迁移的重要因素之一。该尾矿重金属主要以残渣态为主,其中Pb的潜在迁移能力最强,As最弱,顺序为Pb Cd Zn Ni Cr Mn Cu As。     

Simultaneous quantification of dissolved organic carbon fractions and copper complexation using solid-phase extraction

Trace metal cycling in natural waters is highly influenced by the amount and type of dissolved organic C (DOC). Although determining individual species of DOC is unrealistic, there has been success in classifying DOC by determining operationally defined fractions. However, current fractionation schemes do not allow for the simultaneous quantification of associated trace metals. Using operational classifications, a scheme was developed to fractionate DOC based on a set of seven solid-phase extraction (SPE) cartridges. The cartridges isolated fractions based on a range of specific mechanisms thought to be responsible for DOC aggregation in solution, as well as molecular weight. The method was evaluated to determine if it can identify differences in DOC characteristics, including differences in Cu–DOC complexation. Results are that: (1) cartridge blanks were low for both DOC and Cu, (2) differences are observed in the distribution of DOC amongst the fractions from various sources that are consistent with what is known about the DOC materials and the mechanisms operative for each cartridge, (3) when present as a free cation, Cu was not retained by non-cationic cartridges allowing the method to be used to assess Cu binding, (4) the capability of the method to provide quantitative assessment of Cu–DOC complexation was demonstrated for a variety of DOC standards, (5) Cu was found to preferentially bind with high molecular weight fractions of DOC, and (6) estimated partitioning coefficients and conditional binding constants for Cu were similar to those reported elsewhere. The method developed describes DOC characteristics based on specific bonding mechanisms (hydrogen, donor–acceptor, London dispersion, and ionic bonding) while simultaneously quantifying Cu–DOC complexation. The method provides researchers a means of describing not only the extent of DOC complexation but also how that complex will be behave in natural waters.     

Interaction of cuprite with dialkyl dithiophosphates

The interaction of freshly abraded surfaces of cuprite, Cu₂O, with neutral or mildly alkaline aqueous solutions of diethyl or di-n-butyl dithiophosphate (DTP) has been investigated by means of conventional and synchrotron X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy. It was confirmed that DTP adsorbs readily on Cu atoms in the surface layer of the mineral treated with solutions of the collector at pH values near 7 and 9 in the presence of air, and renders the surface hydrophobic. When cuprite is treated with relatively high concentrations of DTP for sufficiently long periods, collector can also be adsorbed as CuDTP, but the coverage does not exceed a thin layer of CuDTP on the adsorbed DTP monolayer, unlike the situation with Cu metal or chalcocite where a thick multilayer can be formed.     

Characterization of Cu-complexes in smectite with different layer charge location: chemical, thermal and EXAFS studies

The retention of Cu and Cu-amino acid complexes by montmorillonite and beidellite, before and after repeated acidified aqueous solution treatments, was studied using X-ray diffraction, chemical and thermal analyses, mass spectrometry and synchrotron-based X-ray absorption spectroscopy (XAS).The results indicate that the extraction of metal complexes from smectites depends on the nature of the layer charge and on the kind of organic species. Cu-cysteine complexes are strongly retained in the interlayer position, whereas Cu-glycine complexes are mostly adsorbed in cationic form which can be easily removed from the silicate layer. The layer periodicity for Cu-smectites treated with glycine shows little or no layer expansion, whereas significant swelling of the layer periodicity is observed in smectites treated with cysteine.Thermal decomposition of both smectites with sorbed Cu-amino acid species shows the evolution of H₂O, NO, CH₃CH₃, and CO₂. In Cu-cysteine treated smectites, the release of H₂S, NO₂, SO₂, and N₂O₃ also occurs.X-ray absorption spectroscopy (XAS) was used to assess the relationships between the structure of the Cu complexes and their desorption from smectites. In Cu-exchanged smectites, the first coordination shell agrees with the hypothesis that the Cu coordinates to oxygen atoms to form monomer and/or dimer complexes. The first coordination shell of Cu in smectites treated with glycine shows four atoms at distances of ∼2 Å. Two of these bonds are with nitrogen and two with oxygen atoms. For copper-cysteine complexes XAS data are compatible with the existence of Cu-N clusters, thus suggesting that Cu links to the amino acid by the aminic group.     

湖南水口山多金属矿区废石堆重金属污染评价及赋存形态分析

湖南水口山及周边是湖南省重金属污染较为严重的地区之一,龙王山金矿床是该区中部的一个重要金矿床.为调查该矿床废石堆污染状况、是否为周边环境的污染源、污染途径、重金属迁移能力和潜在的危害,对矿区FS17废石堆进行了自然淋滤水和24 m浅钻系统取样,开展重金属元素总量分析,利用单因子指数法和内梅罗综合污染指数法对其重金属污染程度进行污染评价,采用四步改良BCR提取法分析废石堆中8种重（类）金属元素（Pb、Zn、Cd、Cu、Cr、Ni、As和Fe）的赋存形态,并利用迁移指数量化废石堆重金属元素迁移能力;发现废石堆中Cd、Cu、Pb、As、Zn、Ni重金属元素严重超标,且在垂向上分布极不均匀;其自然淋滤水样中重金属元素Cd、Ni、Zn、Cu也严重超标;废石堆浅层重金属元素潜在迁移能力顺序为:Cd＞Ni≈Zn＞Cu＞Pb＞As＞Cr＞Fe,深层重金属元素迁移能力顺序为:Cd＞Zn＞Cu＞Ni＞Cr＞Pb＞As＞Fe,浅层重金属元素的迁移性大于深层;说明该废石堆重金属元素含量高,是周围环境重要污染源,酸性废水排放为其释放污染元素的主要途径;Cd、Cu、Zn、Ni迁移能力强,是周围环境的主要污染元素;Pb、Ni、As的迁移性在深层明显降低,可以通过埋深来削弱其迁移性,而Cr不会对周边环境产生污染.      

Deep-penetrating geochemistry of the Tuwu copper deposit, northwestern China

Desert terrains in northern China are covered by widespread regolith sediments which mask geochemical signals from ore bodies and are major obstacles to mineral exploration. There is a critical need to study the vertical distribution of elements in this regolith and to establish optimum sampling and analytical methods. The aim of this study is to understand the dispersion and variation of elements throughout the cover in a vertical profile. The results demonstrate that the main elements show a distribution pattern of enrichment in clay layers in the vertical profile, i.e., most elements tend to be enriched in the most upper part of the profile above the orebodies except for some elements like Cu, Ca and Ag. Meanwhile, both fine (-160 mesh) and coarse (+20 mesh) fraction samples from clay-rich horizons are favorable samples and selective leaching of the elements absorbed on clays or oxide coatings is effective for localizing buried deposits. The distribution of active Cu and Mo is quite different because chalcopyrite is weathered into Cu sulfate and CuCO3, and is precipitated in alkaline environments in a layer below close to the surface. Mo is soluble in the alkaline environment so it can penetrate the caliche layer and be enriched on the surface of soil enriched with weakly cemented clay.