1,3-丙二胺改性纳米金刚石表面及其表征

由于纳米金刚石相对表面积较大,这使其处在不稳定状态,常常以团聚的形式存在,导致其优良性能无法充分发挥。纳米金刚石颗粒表面改性是改善纳米金刚石颗粒与各种基质的相容性的常见且有效的方式。本文主要研究了对纳米金刚石进行石墨化处理、酸化处理、酰氯化处理后,在其表面嫁接1,3-丙二胺,并对其进行表征,期望改性后的纳米金刚石能够在溶液中形成长期稳定的分散。     

构造煤纳米孔隙结构演化及分形特征

基于液氮吸附实验研究了构造煤纳米孔隙结构特征,采用FHH模型探讨了孔隙分形特征及其储层物性意义。结果表明:煤纳米孔隙结构受构造作用控制明显,孔容和比表面积均呈2个突变点、3段式的变化规律。构造煤纳米孔隙具有显著的分形特征,分维数随煤构造变形程度的增强而增大。构造变形可提高煤的吸附能力,而渗透性在脆性变形煤中有所改善。     

掺硼金刚石薄膜表面高分散镍纳米颗粒的制备

化学气相沉积制备掺硼金刚石薄膜因具有电化学势窗口宽、化学稳定性高和抗污能力强等特征，在电化学领域中有广阔的应用前景。用高分散金属纳米颗粒对掺硼金刚石（BDD）薄膜进行表面修饰，可显著提高其比表面积和活性位点，提升掺硼金刚石薄膜的电化学性能。采用混合酸对掺硼金刚石薄膜进行表面改性，获得亲水性表面，继而生长镍金属框架材料（Ni-MOFs），热处理后获得镍纳米颗粒。借助接触角测定仪对薄膜表面终端进行分析，并通过扫描电子显微镜对纳米镍颗粒修饰的BDD薄膜进行表征。结果表明：BDD表面从以氢端基为主的H-BDD转变为以氧基团为主的O-BDD表面，接触角由70 °减小为33.7 °；纳米镍颗粒分散均匀，粒径大小为5—12 nm，颗粒密度约为3.5×10⁶ cm^-2。     

不同温度条件下煤层气等温吸附试验研究

为了研究不同温度下煤层气吸附规律,依据高温容量法对煤样进行一系列等温吸附试验,由BET多层吸附理论将得到的实际吸附体积换算为最大单层饱和吸附气体体积,在Langmuir单分子层吸附模型上处理数据,得到两种煤样的定容吸附曲线、等温吸附曲线和Langmuir常数a、b分别与温度的拟合曲线。结果表明:1)在低温低压区煤与甲烷气体的吸附是单分子层的,且单层吸附尚未饱和,随着温度和压力逐渐变大,易发生多层吸附;2)Langmuir常数a表征煤体的吸附能力,随着温度升高,因煤体比表面积不断增大,a值缓慢增大;3)Langmuir常数b随温度升高下降趋势明显,说明温度对解吸的促进作用更加明显。     

纳米金刚石团聚体在白油介质中的解聚与分散

采用机械化学方法, 对爆轰法合成的纳米金刚石团聚体进行表面改性, 实现了纳米金刚石在白油体系中的解团聚和稳定分散。采用红外光谱等分析, 对几种聚合物分散剂在纳米金刚石表面的吸附机理进行了研究。利用适当用量的聚合物分散剂进行机械化学改性, 可以得到良好分散的体系。在白油体系中, 分散剂吸附产生的空间位阻作用是纳米金刚石分散稳定的主要机制。     

捕收剂在油团聚中的作用

本文通过油酸钠在黑钨矿表面吸附量的测定及黑钨矿油团聚的试验结果证实,对于不同粒度级别的黑钨矿开始发生球形团聚时,所需要的油酸钠最低用量是当油酸钠在黑钨矿粒子表面产生约为1/2单分子层吸附;当吸附厚度接近一个单分子层吸附时,油团粒度最大,油团生长速度最快,油团效果最佳;而吸附超过单分子层厚度时油团效果变坏。     

十二胺和十二烷基磺酸钠在长石石英表面的吸附

采用浮选试验、ζ-电位和FTIR光谱分析,研究了十二胺(阳离子捕收剂,DDA)和十二烷基磺酸钠(阴离子捕收剂,SDS)作捕收剂在长石石英表面的吸附。浮选结果表明,pH值在2附近时,长石和石英的浮游差最大,混合捕收剂能增大二者的浮游差,有利于长石的优先浮选。在单一捕收剂中长石和石英ζ-电位均整体向正或负方向移动,在混合捕收剂溶液中,二者ζ-电位在碱性介质中正移幅度较酸性介质明显。FTIR光谱结果表明,pH值为2时,DDA在长石和石英表面均只存在物理吸附;SDS在长石表面既存在物理吸附,还与Al-O形成化学吸附,而在石英表面仅存在物理吸附;混合捕收剂在长石表面既有物理吸附,还存在氢键作用,而在石英表面仅存在物理吸附。     

后处理对爆轰纳米金刚石表面官能团的影响

分别在高锰酸钾与浓硫酸的混合溶液、空气、氢气、真空以及氩气中对爆轰纳米金刚石进行后处理,研究了后处理方法对其表面官能团的影响。采用X射线衍射仪、高分辨透射电子显微镜、傅立叶变换红外光谱仪和差示扫描量热仪对后处理前后纳米金刚石的微观结构、性能和表面状态进行了研究。结果表明:纳米金刚石颗粒形状为球形或椭球形,平均粒径约为5 nm,在空气中的起始氧化温度约为550 ℃,在氢气、真空和氩气中的石墨化温度分别约为284 ℃、1 146 ℃和1 184 ℃。纳米金刚石在后处理前表面含有大量的官能团,如-OH、-CH₃、-CH₂、CO₂、-C==O、-COOH和-C-O-C等。在氢气中对纳米金刚石进行处理,可使部分官能团从表面解吸而由氢取代,悬键与氢结合可有效防止二次吸附,是去除爆轰纳米金刚石表面官能团的低成本、高效方法。     

煤体对瓦斯吸附热的理论研究

系统地阐述了吸附热产生的微观机理，根据势能模型，得到了基于玻尔兹曼分布的两能态模型，并推导出相应的吸附热计算公式。根据巨正则系综理论，得到了朗缪尔单分子层统计力学模型，并推导出相应的吸附热计算公式；引入德布罗意平均热波长后，得到了朗缪尔单分子层模型吸附热的近似计算公式。比较两种模型的结果可以看出：吸附热受吸附量、吸附中心和分子间平均距离的影响较大，对于外层瓦斯(相对于煤体表面)和内层瓦斯应该采用不同的物理模型进行分析。根据朗缪尔单分子层模型，从吸附的角度出发，研究了煤体表面结构的分形特征，并将二维平面吸附推广到分形表面吸附，得到了基于德布罗意平均热波长的分形维数。     

页岩气超临界吸附机理分析及等温吸附模型的建立

为认识页岩气吸附机理,抓住页岩气所处超临界态的特点,同时考虑页岩多尺度孔隙空间和黏土矿物与干酪根吸附能力的差异性,理论分析了页岩气超临界吸附机理,同时建立了DALangmuir等温吸附模型。分析表明:低压阶段,甲烷优先吸附在干酪根超微孔表面,以微孔充填形式吸附;高压阶段,甲烷以单分子层形式吸附在中孔和大孔表面。甲烷脱附优先发生在中孔和大孔表面,表现出"吸附滞后"现象。建立的吸附方程拟合结果的R2大于0.995。页岩气吸附方式因吸附剂吸附能力和孔径而异,吸附方式既有单分子层吸附也有微孔充填吸附。吸附滞后现象是吸附剂吸附能力差异性的集中体现。所建模型可反映黏土矿物与干酪根吸附能力的差异及不同孔径吸附状态的差异,模型参数物理意义明确,数据拟合精度较高。     

Removal of Mn2+ from aqueous solution by manganese oxide coated zeolite

The preparation, characterization, and adsorption properties of Mn²⁺ by manganese oxide coated zeolite (MOCZ) and its ability in removing Mn²⁺ by adsorption were investigated. Characterization analyses were used to monitor the surface properties (and their changes) of the coated layer and metal adsorption sites on the surface of MOCZ. The adsorption experiments were carried out as a function of solution pH, adsorbent concentration and contact time. Binding of Mn²⁺ ions onto MOCZ was highly pH dependent with an increase in the extent of adsorption with the pH of the media investigated. After the Mn²⁺ adsorption by MOCZ, the medium pH decreased and enhanced with increasing adsorbent concentration. The pseudo-second-order model fitted better among all the kinetic models suggesting that the adsorption mechanism might be a chemisorption process. The equilibrium data showed excellent correlation for both Langmuir and Freundlich isotherm model and this implies both monolayer adsorption and a heterogeneous surface existence in MOCZ. At pH = 6, the Mn²⁺ uptake by MOCZ attained as high as 1.1 meq Mn²⁺ g^?1 at equilibrium. The results suggested that MOCZ presents a fairly good potential as an adsorbent for an efficient removal of Mn²⁺ ions from aqueous solution.     

高温焙烧对含蛇纹石尾矿亚甲基蓝吸附性能的影响

富镁硅酸盐矿物蛇纹石具有比表面积大、天然卷曲结构、孔道结构丰富等特点，可作为优良的吸附材料。为实现蛇纹石资源的综合利用，通过高温焙烧方法对蛇纹石尾矿进行了改性研究，考察了焙烧蛇纹石尾矿对水相中亚甲基蓝的吸附性能。研究结果表明，与原矿相比，焙烧后的蛇纹石尾矿对亚甲基蓝具有较好的吸附效果，饱和吸附量约为11.27 mg/g；随着尾矿用量和吸附时间的增加，亚甲基蓝的吸附率也随之增加，且在中性和碱性条件下达到最好的吸附效果。焙烧后的蛇纹石尾矿对亚甲基蓝的吸附过程符合准二级动力学模型和Langmuir吸附等温线模型，吸附类型属于化学吸附，吸附方式为单分子层吸附。以上研究表明，高温焙烧利于蛇纹石尾矿对亚甲基蓝的吸附，可促进蛇纹石尾矿的综合利用。      

NaOH改性粉煤灰对废水中Pb2+的吸附特性研究

采用批吸附试验探究NaOH改性粉煤灰对含Pb2+废水吸附特性。结果表明,NaOH改性粉煤灰对Pb2+具有较强的吸附效果,在固液比为0.9 g/L、温度为25℃、Pb²⁺溶液质量浓度为100 mg/L条件下,吸附反应在30 min基本达到平衡,Pb2+去除率为96.02%,吸附容量为106.69 mg/g。由吸附等温线模型得出吸附主要在单分子层表面进行。吸附动力学特征表明吸附主要限速步骤为化学吸附。吸附反应存在物理吸附和化学吸附。     

Kinetics of collector adsorption on mineral surfaces

In the present study infrared attenuated total reflection (IR-ATR) was used to monitor the rate of in situ adsorption of heptyl xanthate on a layer of zinc sulphide synthesized on a germanium ATR crystal. The zinc sulphide surface was characterized using X-ray photoelectron spectroscopy (XPS). The absorbance of heptyl xanthate measured increased with increasing bulk concentration of the adsorbate up to an equilibrium plateau value corresponding to a fractional coverage of the surface sites of the substrate. For the adsorption from solutions of concentrations between 10⁻³ and 10⁻⁵ M, the rate of adsorption increased with increasing bulk concentration. At higher concentrations the measured absorbance should be corrected for the absorbance due to the concentration of xanthate in bulk solution. The present work provides a discussion of this correction. Assuming the adsorption stage to be rate-controlling and proportional both to the concentration of the adsorbing species in solution and unreacted surface area, a rate law governing this type of transient adsorption kinetics was derived. By means of absorbance data for the concentrations 0.1 and 0.01 mM, the rate constant of adsorption was calculated. From the initial part of a Langmuir adsorption isotherm, the absorbance at monolayer coverage and the equilibrium constant of adsorption could be estimated.     

基于吸附势理论的煤对N_2吸附特性的研究

利用ASAP2020比表面积分析仪研究了阳泉煤在液氮浴(77K)条件下对N2吸附特性,根据该温度下的吸附等温线确定出ε-ω吸附特性曲线,同时根据Langmuir单分子层吸附模型和BET多分子层吸附模型得出了完全相同的ε-ω吸附特性曲线,表明ε-ω吸附特性曲线与煤对N2吸附的吸附模型无关。因此可以根据ε-ω吸附特性曲线确定不同温度下的吸附等温线。     

改性吸附剂对水中Cu(Ⅱ)的去除效果研究

以改性有机肥为吸附剂吸附水中Cu(Ⅱ),探究了Cu(Ⅱ)初始浓度、吸附时间、吸附温度、吸附剂用量、转速和溶液初始pH值等因素的影响。结果表明,pH=5、温度30 ℃、转速150 r/min时,改性吸附剂吸附Cu(Ⅱ)在2 h达到吸附平衡;吸附剂用量为8 g/L时,吸附量最大;吸附过程符合准二级动力学方程,等温吸附曲线符合Langmuir方程,说明其吸附为单层吸附。     

2-mercaptobenzothiazole and derivatives in the flotation of galena, chalcocite and sphalerite: A study of flotation, adsorption and microcalorimetry

The results of flotation, using 2-mercaptobenzothiazole (MBT) and its derivatives, 6-methyl-MBT (MMBT), 6-methyloxy-MBT (MOMBT), 6-propyloxy-MBT (PrOMBT), and 6-pentyloxy-MBT (POMBT) on pure mineral samples showed some important advantages in the flotation of galena at neutral pH and low collector dosages. It has been found that MBT shows a high affinity towards surfaces containing lead and copper but no selectivity. The introduction of a pentyloxy ring substituent led to a change in the adsorption kinetics, as shown by microcalorimetry, and an improvement of the affinity towards galena.The basic mechanism of adsorption of MBT on galena and chalcocite has been studied by thermochemical measurements, showing that the adsorption mechanisms of MBT on both minerals are comparable in the initial step, involving the chemisorption of the collector. At concentrations above monolayer a second surface reaction of MBT on galena has been observed and attributed to an oxidative dimerisation.Comparative experiments on adsorption properties of mercapto-benzo-oxazole (MBO) show the important role of the endocyclic element composition on the sorption process. The endocyclic O-atom in MBO prevents chemisorption on galena whereas strong coordinative bonds will be formed on Cu containing surfaces.     

The ability of static secondary ion mass spectrometry to discriminate submonolayer from multilayer adsorption of thiol collectors

Experiments have been carried out to establish whether static time-of-flight secondary ion mass spectrometry (ToF-SIMS) alone is able to differentiate monolayer and multilayer coverage of thiol collectors on sulfide minerals. The systems investigated were those for which X-ray photoelectron spectroscopy is able to provide an independent determination of the extent of coverage, and included diethyldithiophosphate (DTP) and 2-mercaptobenzothiazole (MBT) on chalcocite, DTP on Ag_2+∂S, and iso-butyl xanthate (BX) and MBT on galena. For adsorption of a thiol collector (TC) on copper and silver sulfides, TC and metal(TC)H ions were detected for both monolayer and multilayer coverage. For multilayer coverage only, metal(TC)₂ ions were evident, notwithstanding the fact that other spectroscopic measurements had revealed the stoichiometry of the principal multilayer species to be metal(TC). For adsorption on galena, TC and metal(TC) ions were observed for both monolayer and multilayer coverage, whereas for multilayer coverage only, fragment ions from Pb(TC)₂ and (TC)₂ species were evident. Indeed, for all the systems studied, static ToF-SIMS was able to distinguish monolayer from multilayer coverage. However, differentiation was reliable only when both positive and negative secondary ion spectra were determined, and possible only because the multilayer species on copper and silver sulfides included a low concentration of metal dithiolate. In light of those findings, unequivocal differentiation by means of static SIMS is expected to be possible for all thiol collector/sulfide systems.