基于第一性原理计算Ca掺杂MoS_(2)对焊接气体的吸附性能

工业焊接的过程中会产生焊接废气例如CO、NO_(2)和CH_(4),这些气体会对工作人员的身心健康造成威胁,为解决这种废气吸附的需求,此文用基于密度泛函理论的第一性原理方法,搭建了Ca掺杂MoS_(2)的模型,用Dmol3模块研究掺杂后的电子结构,并计算了Ca-MoS_(2)吸附CO、CH_(4)和NO_(2)三种气体的态密度、电荷转移、吸附能、电子密度差等参数.结果表明Ca-MoS_(2)对于CH_(4)是一种物理吸附,主要是范德华力作用,而Ca-MoS_(2)吸附CO和NO_(2)是一种化学吸附,存在较强的吸附能力.此类掺杂有望制成新的气敏传感器等有益结果,该工作具有一定意义.

Adsorption equilibrium, kinetics, and dynamic separation of Ca2+ and Mg2+ ions from phosphoric acid–nitric acid aqueous solution by strong acid cation resin

The separation of Ca2+and Mg2+ions from phosphoric acid-nitric acid aqueous solution is very significant for the neutralization process of nitrophosphate fertilizer.This paper studied the adsorption equilibrium,kinetics,and dynamic separation of Ca2+and Mg2+ions by strong acid cation resin,and the effects of phosphoric acid and nitric acid on the adsorption process were investigated.The results reveal that the adsorption process of Ca2+and Mg2+ions in pure water on resin is in good agreement with the Langmuir isotherm model and their maximal adsorption capacities are 1.86 mmol·g-1 and 1.83 mmol·g-1,respectively.The adsorption kinetics of Ca2+and Mg2+ions on resin fits better with the pseudo-first-order model,and the adsorption equilibrium in pure water is reached within 10 min contact time,while at the present of phosphoric acid,the adsorption rate of Ca2+and Mg2+ions on resin will go down.The dynamic separation experiments demonstrate that the designed column adsorption is able to undertake the separation of metal ions from the mix acids aqueous solution,but the dynamic operation should control the flow rate of mix acid solution.Besides nitric acid solution was proved to be effective to completely regenerate the spent resin and achieve the recyclable operation of separation process.

煤吸附CO_(2)压缩因子快速计算模型研究

为研究Virial、V-d-W、R-K、S-R-K、P-R、童景山等6种工程常用气体状态方程中适合煤吸附CO_(2)压缩因子最优方程及快速计算模型,以3种不同变质程度煤样为研究对象,采用容量法实测了试验温度为30℃时应用以上6种方程所得煤的CO_(2)吸附量、CO_(2)吸附常数及吸附等温线。研究表明:与美国国家标准技术研究所(NIST)提供的CO_(2)压缩因子相比,采用Virial状态方程得到的CO_(2)压缩因子最大、绝对误差最小,为0.38%;吸附等温线拟合优度最高,CO_(2)吸附常数a值绝对值误差最小,确定出煤吸附CO_(2)压缩因子最优方程为Virial方程;同时,提出试验温度为30℃时,CO_(2)压缩因子一种简便快捷计算模型,经检验,该模型相对美国标准计算所得CO_(2)吸附常数a值绝对值误差最大不超过1%,且操作简便,快速精确。

煤层亚临界/超临界CO_(2)吸附特征与封存模式

大规模高效CO_(2)地质封存是短期内快速实现CO_(2)减排的关键途径之一,以吸附特征为主要封存机制的深部不可采煤层CO_(2)封存具有规模化实施的潜力。为研究深部煤层CO_(2)封存机制,以沁水盆地无烟煤为研究对象,开展了高温高压CO_(2)吸附实验,并采用简化局部密度模型(SLD-PR)拟合,分析了温压变化下不同孔隙的吸附相密度分布特征,揭示了以吸附相密度和最大吸附层厚度协同变化为核心的煤层CO_(2)封存机理,最后通过准确划分孔内吸附空间与自由空间,预测了不同埋深下煤层CO_(2)封存量。研究结果表明:(1)不同温度下超临界CO_(2)吸附曲线均表现出典型的超临界气体吸附特征,过剩吸附量(最大值介于1·25~1·75 mmol/g)在达到最大值后下降;(2)孔隙内CO_(2)吸附层分为接触层、内层和过渡层,亚临界CO_(2)在孔内以单分子层吸附为主,而超临界CO_(2)吸附方式为多分子层吸附;(3)最大吸附层厚度随埋深增加而减小,与温度呈正相关,而与压力呈负相关;(4)CO_(2)平均吸附相密度随埋深“先增后减”,总封存量与绝对吸附量曲线在CO_(2)处于超临界状态下存在差异。结论认为:(1)在吸附空间与吸附相密度协变下,煤层CO_(2)微观封存模式随埋深可分为亚临界单分子层吸附、超临界类气态多分子层吸附型以及超临界类液态多分子层吸附3种类型,自由相封存量对总封存量的贡献随埋深增加,但吸附封存仍是煤层CO_(2)封存的主要方式;(2)研究成果揭示了原位煤层超临界CO_(2)封存机理,能够为深部煤层CO_(2)封存能力评价提供新认识。

Measurement of CO_(2) adsorption capacity with respect to different pressure and temperature in sub-bituminous: implication for CO_(2) geological sequestration

CCUS (carbon capture, utilization, and storage) technology is regarded as a bottom method to achieve carbon neutrality globally. CO_(2) storage in deep coal reservoirs serves as a feasible selection for CCUS, and its storage potential can be attributed to the CO_(2) adsorption capacity of the coal. In this paper, a series of CO_(2) adsorption isotherm experiments were performed at different pressures and temperatures in sub-bituminous coal from the southern Junggar Basin (reservoir temperature ∼25.9°C and pressure ∼3.91 MPa). In addition, the high-pressure CO_(2) adsorption characteristics of the southern Junggar Basin coal were characterized using a supercritical D-R adsorption model. Finally, the CO_(2) storage capacities in sub-bituminous coal under the in situ reservoir temperature and pressure were analyzed. Results indicated that the excess adsorption capacities increase gradually with increasing injection pressure before reaching an asymptotic maximum magnitude of ∼34.55 cm3/g. The supercritical D-R adsorption model is suitable for characterizing the excess/absolute CO_(2) adsorption capacity, as shown by the high correlation coefficients > 0.99. The CO_(2) adsorption capacity increases with declining temperature, indicating a negative effect of temperature on CO_(2) geological sequestration. By analyzing the statistical relationships of the D-R adsorption fitting parameters with the reservoir temperature, a CO_(2) adsorption capacity evolution model was established, which can be further used for predicting CO_(2) sequestration potential at in situ reservoir conditions. CO_(2) adsorption capacity slowly increases before reaching the critical CO_(2) density, following a rapid decrease at depths greater than ∼800 m in the southern Junngar Basin. The research results presented in this paper can provide guidance for evaluating CO_(2) storage potential in deep coal seams.

Insights into the adsorption performance and mechanism of hydrated Ca ion on talc(001) basal surface from DFT calculation

The utilization of Ca ion as assistant depressant of CMC on talc has been widely reported.Thus,the study on the adsorption mechanism of Ca ion on talc surface is very crucial for understanding the performance of CMC on talc depression.In this paper,mechanism insights into hydrated Ca ion adsorption on talc(001) basal surface were creatively provided using DFT calculation.[Ca(H_(2)O)_6]^(2+) and [Ca(OH)(H_(2)O)_(3)]^(+) were determined as the effective hydrate components for Ca ion adsorption,and the top O site was the most favorable position for their adsorptions on talc surface.Furthermore,the adsorption mechanisms of [Ca(H_(2)O)_6]^(2+) and [Ca(OH)(H_(2)O)_(3)]^(+) on talc surface were found to be not the Ca-O chemical bond,but the hydrogen bonding formed by the H atom of the H_(2)O ligand and the surface O atom.H_(2)O acted like a bridge to connect them to the talc surface.Moreover,the hydrogen bonding was formed due to the hybridization of H 1s orbital with the O 2s,O 2p orbitals.Simultaneously,electrons transferred between the H atom and the surface O atom.This work provides theoretical insights into the Ca ion adsorption on talc surface,which can help deeply understand the talc flotation using CMC as depression.

Modelling and experimental investigation of effects of moisture and operating parameters during the adsorption of CO2 onto polyaspartamide

Parametric effect of moisture and influence of operating variables on the adsorption behaviour of polyaspartamide during CO2 capture was investigated in this study using experimental and modelling approach. Individual effects of operating conditions (e.g. pressure, temperature and gas flow rates) as well as the effect of moisture on the adsorption capacity of polyaspartamide were methodically investigated using Dubinin-Raduskevich model. Results from the investigations reveal that the presence of moisture in the flue gas had an incremental effect on the adsorption capacity of polyaspartamide;thereby showcasing the potential of polyaspartamide as a suitable hydrophilic material for CO2 capture in power plants. In addition, pressure, temperature and gas flow rates at 200 kPa, 403 K, and 1.5 mL/s, respectively, sig? nificantly influenced the CO2 adsorption capacity of polyaspartamide. Physisorption and chemisorption both governed the adsorption process while equilibrium studies at different temperatures showed that Langmuir isotherm could adequately describe the adsorption behaviour of the material with best fit with R^2>0.95.

活性炭纤维对SO_(2)饱和吸附量的测定方法改进

“绿色化学”是当前化学实验教学中重要的课程思政元素,“活性炭纤维对SO_(2)饱和吸附量的测定”作为综合性实验具有现实意义。而传统的对SO_(2)吸附量的测定方法存在仪器昂贵、操作复杂、危险性等问题,不适合应用于实验教学,同时也不适用于一些硬件设施有限的中小型实验室中进行科学研究。通过参考国家环境保护总局标准HJ/T56-2000《固定污染源排气中二氧化硫的测定.碘量法》并进行方法及装置的改进,可以有效的测定活性炭纤维材料对SO_(2)的饱和吸附量。新方法操作简单、安全、成本较低,为实验室开展相关教学及中小型实验研究具有参考意义。

732型阳离子交换树脂对渗滤液中Ca^(2+)、Mg^(2+)的去除

机械蒸汽压缩(MVC)蒸发处理渗滤液过程中,Ca^(2+)和Mg^(2+)的大量存在会导致结垢及浓缩液后续处理困难等问题。通过静态吸附实验,探索了732型阳离子交换树脂对渗滤液中Ca^(2+)、Mg^(2+)的吸附特性。实验结果表明,在pH=7、温度为30℃、732型阳离子交换树脂投加量为8g/L、吸附时间为30 min的条件下,对于Ca^(2+)和Mg^(2+)(摩尔比为3∶5)的质量浓度为2 000mg/L的混合溶液,两者的去除率分别为88.8%、68.3%。732型阳离子交换树脂对Ca^(2+)和Mg^(2+)的吸附行为均符合Langmuir吸附等温方程,相关性系数(R2)分别为0.992 5、0.952 3。利用732型阳离子交换树脂处理实际渗滤液,吸附条件与混合溶液相同,结果表明,对实际渗滤液中Ca^(2+)和Mg^(2+)的去除率分别达到为69.9%、70.9%。经过732型阳离子交换树脂吸附预处理后的渗滤液再经MVC蒸发处理,可有效减少MVC蒸发过程中的结垢,并降低浓缩液后续处理成本。

煤泥对水溶液中Ca^2＋的吸附性能研究

在静态条件下,研究了Ca2+在煤泥表面的吸附动力学。考察了不同Ca2+初始浓度的吸附实验,并对实验结果进行了动力学方程的拟合,结果表明,煤泥对Ca2+的吸附过程较好地符合准二级动力学方程。研究了初始Ca2+浓度、溶液pH值、振荡速度和煤泥质量对Ca2+吸附量的影响,实验结果表明:(1)煤泥对Ca2+吸附量随着Ca2+溶液浓度的增加而增大,Ca2+浓度大于3.828 mmol/L时,吸附量基本保持不变;(2)溶液pH<9时煤泥颗粒对Ca2+的吸附主要是静电吸附,pH>9时Ca2+在煤泥表面主要是沉淀吸附和一羟基吸附;(3)Ca2+在煤泥表面吸附的最佳振荡强度为150 r/min。

生理条件下PDF对Pb^(2+)、Cu^(2+)、Zn^(2+)、Ca^(2+)的吸附研究

在生理条件下(pH2和pH7,37℃),用马铃薯膳食纤维(PDF)对金属离子Pb2+、Cu2+、Zn2+、Ca2+进行吸附试验。结果表明,两种酸度条件下PDF对Pb2+的吸附较大,对Cu2+、Zn2+的吸附较小,对Ca2+吸附很小;PDF用量增大(减小),吸附量(qe)减小(增大)。PDF对重金属离子的吸附表明PDF具有较好的生理活性。用作膳食纤维时应根据需求,按照已研究的用量与吸附量关系配制。其吸附作用是化学吸附与物理吸附的综合结果。PDF的疏松结构和红外光谱中较多的醛羧基团证明了这一点。吸附数据线形拟合表明物理吸附符合Ligniur单分子层吸附机理。

4A分子筛与Ca^(2+)在热水中离子交换的实验研究

研究了4A分子筛吸附热水中Ca2+的效果,考察了浓度、温度、pH对吸附量的影响。结果表明:该反应为拟一级可逆反应,交换过程为液膜控制,并在40~60h吸附达到平衡。绘制了不同温度下的离子交换等温线,其吸附规律符合Langmuir吸附等温式;50℃时,4A分子筛对Ca2+的最大吸附量可达61.73mg/g。随着Ca2+初始浓度的增加分子筛对Ca2+的去除率逐渐降低;温度增加,Ca2+在分子筛上的吸附量增加;pH增加,吸附量也增加,并且碱性条件下吸附量更高。

叶面喷Ca^(2+)增加海滨锦葵幼苗对高温的适应能力

以10 mmol.L-1CaC l2溶液喷洒海滨锦葵(Kosteletzkya virginica)幼苗叶片,7 d后将其转移至40℃培养箱中高温培养,定期测定有关生理生化指标。结果表明:Ca2+处理组海滨锦葵幼苗的脯氨酸和可溶性糖含量较对照组低,萎蔫程度明显轻于对照组,根系活力下降幅度小于对照组;Ca2+处理可有效抑制膜透性的加大,提高Ca2+-ATPase活性。Ca2+处理能提高海滨锦葵幼苗的耐热性。

大孔型离子交换树脂脱除食品稀糖液中Ca^(2+)、Mg^(2+)的初步研究

研究了3种大孔型阳离子交换树脂脱除稀糖液中Ca(2+)、Mg(2+)的效果，其中Amberlite252对Ca(2+)、Mg(2+)的交换能力最大，除去效果最好。研究还证实，该树脂的交换容量与稀糖液的PH值和操作流速有很大的关系。

Ca^(2+)引入方式及用量对蒙脱石的膨胀容及阳离子交换量的影响

探讨了Ca(OH)2,CaCl2掺入量对蒙脱石的膨胀容及阳离子交换量的影响,并对改性前后蒙脱石的显微结构进行了分析.研究结果表明,不论是普通蒙脱石还是钠基蒙脱石,经Ca2+处理后二者的膨胀容均有所下降,但改性普通蒙脱石下降的幅度要大于改性钠基蒙脱石的.随着Ca(OH)2,CaCl2掺入量的增加,膨胀容减小.当掺入8%(wt)CaCl时,蒙脱石的膨胀容较小、交换性钙较低、结构紧密.

油茶果壳对Al^(3+)和Ca^(2+)的吸附性能研究

探讨油茶果壳对Al^(3+)和Ca^(2+)的吸附性能,为果壳的资源化利用及林地施肥提供理论依据。利用果壳吸附溶液中的Al^(3+)和Ca^(2+),通过红外光谱分析和模型拟合,对其吸附特性进行了初步探讨。结果表明:1)果壳结构中含有大量的羧基和羟基等官能团,这些官能团能够提供与Al^(3+)和Ca^(2+)进行离子交换的H+;2)果壳对Al^(3+)和Ca^(2+)的吸附符合Freundlich模型,对Al^(3+)和Ca^(2+)的理论最大吸附量分别为11.39、11.04 mg/g;3)吸附过程符合准二级动力学模型,对Al^(3+)和Ca^(2+)的吸附过程主要受化学作用的控制,膜扩散和颗粒内扩散共同决定果壳吸附Al^(3+)和Ca^(2+)的速率;4)Al^(3+)和Ca^(2+)共存情况下,果壳对Al^(3+)的吸附高于Ca^(2+),且果壳对混合溶液中Al^(3+)和Ca^(2+)的吸附比单一溶液中的减少,二者之间存在竞争;5)油茶果壳是一种对Al^(3+)和Ca^(2+)有较好吸附性能的廉价吸附材料。

CaCO3和CaSO4·2H2O共同作用下Ca2+对C3A水化浆体固化氯离子性能的影响

采用平衡法研究了CaCO 3和CaSO 4·2H 2 O共同存在时Ca 2+对C3A水化浆体氯离子固化能力、生成产物和氯盐溶液pH值的影响.结果表明:C3A水化浆体固化氯离子后生成含氯铝酸盐并释放OH-,提高了氯盐溶液的pH值;CaCO 3和CaSO 4·2H 2 O分别作用时均会降低C3A水化浆体的氯离子固化能力和氯盐溶液pH值的提高程度,CaCO 3和CaSO 4·2H 2 O共同作用时则会显著降低C3A水化浆体的氯离子固化能力;C3A水化浆体中含氯铝酸盐生成量和氯离子固化能力随氯盐溶液pH值的降低而减小,而Ca 2+会降低氯盐溶液pH值的提高程度,但能提高C3A水化浆体的氯离子固化能力,CaCO 3或CaSO 4·2H 2 O单独存在时都能使Ca 2+提高氯离子固化能力的效果更为显著,且CaCO 3比CaSO 4·2H 2 O的作用更加明显,但CaCO 3和CaSO 4·2H 2 O共同存在时会出现负协同作用;在CaCO 3和CaSO 4·2H 2 O共同作用下,Ca 2+促进各水化产物与氯离子反应生成含氯铝酸盐的效果由小到大为:AFt<C3AH 6<AFm<碳铝酸钙水化物,同时改变了所生成含氯铝酸盐(固溶体)的物相结构.

改性文冠果活性炭吸附Ca^2+的研究

采用硝酸对文冠果活性炭进行氧化改性,探讨了Ca^2+溶液初始浓度、吸附温度、时间、pH值对Ca^2+吸附的影响。分析了吸附热力学和动力学,初步探讨了吸附机理。实验表明,当Ca2+的初始浓度为500 mg/L,吸附温度为40℃,吸附时间为120 min,pH值为2时,吸附量最大,可达285.9 mg/g。硝酸改性文冠果活性炭吸附Ca2+符合伪二级动力学模型和Langmuir等温线模型,吉布斯自由能ΔG°<0、焓变ΔH°<0、熵变ΔS°<0,表明该吸附是一个自发的放热过程。

大孔树脂对食品糖液中Ca^(2+)、Mg^(2+)离子的吸附特性研究

研究了A252大孔树脂对糖液中Ca2+、Mg2+的吸附效果。结果表明,该树脂对Ca2+、Mg2+的交换能力大,吸附效果好,且该树脂的交换容量与糖液的pH值和流速相关。

响应面法优化Ca^(2+)激活牦牛血中凝血酶原工艺研究

以牦牛血液为原料,采用柠檬酸钡吸附法制取凝血酶原。选取激活温度,Ca2+终浓度,激活时间三个因素,在单因素实验基础上进行Box-Behnken中心组合实验,研究了Ca2+激活牦牛血中凝血酶原的工艺条件,实验结果表明:激活温度27℃、Ca2+终浓度0.01mol/L、激活时间1.95h,在此条件下凝血酶的比活力最优为63.3972U/mg。