海藻酸钠与钙或锌离子吸附平衡过程研究

使用原子吸收分光光度法测定了海藻酸钠对锌、钙离子的吸附平衡过程。试验结果表明,海藻酸钠对钙离子的结合能力较强,对锌离子的吸附容量较高。吸附平衡热力学数据表明海藻酸钙体系较为稳定;混合离子吸附的试验结果表明对钙、锌离子的选择性系数为1.35;钙锌离子交换试验表明钙离子与锌离子在海藻酸古洛糖醛酸片段的离子交换会影响锌离子与甘露糖醛酸片段的结合。     

生物吸附剂对废水中钙离子的去除试验

用活性污泥与沸石按一定比例配制成一种生物吸附剂,并在静态条件下,进行了生物吸附剂对废水中钙离子的去除试验和机理探讨。考察了生物吸附剂配方中活性基体用量、沸石用量及搅拌条件、溶液浓度、pH值等因素对钙离子去除效果的影响。结果表明:用生物吸附剂去除钙离子可以获得较好的效果,去除速度快,出水钙离子的质量浓度可降到200mg/L以下,满足工业循环水回用要求;去除机理可能有生物吸附、静电吸附、化学沉淀和离子交换;适当的剪切力可以加速吸附反应的进程,证实了流体力化学效应的存在。     

轻质碳酸钙分散、改性装置的研究

针对国内轻质碳酸钙普遍存在分散、改性效果不理想的情况,重点介绍了两种强机械力分散、改性装置。     

Phosphate sorption approach for determining phosphorus requirements of wheat in calcareous soils

Five field experiments involving P application rates from 0 to 66 kg P ha^–1 were conducted on irrigated wheat at Tandojam, Pakistan. The soils belonged to two great soil groups, Torrifluvent and Camborthid. All soils were calcareous. Olsen-P contents ranged from 3.5 to 6.3 mg P kg^–1. Phosphate sorption curves were developed for soils from control (no P) plots at each site. Concentrations of P in solution established by fertilization in the field as estimated from the sorption curves ranged from 0.008 to 0.16mg P L^–1. Actual grain yields were converted to relative grain yields and plotted against corresponding concentrations of P in solution. Yield response to P application was obtained in each experiment. Control plot yields ranged from 57 to 89% of maximum yield of respective experiments. Phosphorus requirements of wheat were 0.032 mg L^–1 for 95% yield as determined from a composite yield response curve. Predicted quantities of P required to attain 0.032 mg P L^–1 ranged from 18 to 29 kg P ha^–1. The results of the study suggest that the P sorption approach can be used as a rational basis for making P fertilizer recommendations for various soil-crop combinations.     

磁场对碳酸钙析晶过程影响的定量研究

借助析晶动力学监测系统，研究了一定强度的磁场对碳酸钙过饱和溶液的析晶过程的影响。定量的、可重复的数据表明，在一定的Ca^2 和CO3^2－浓度范围内，磁场对碳酸钙晶体的生长析出具有明显的抑制作用。对不同溶液进行磁处理的实验结果显示，磁场阻垢既通过成垢阳离子Ca^2 起作用，也通过成垢阴离子CO3^2-起作用。     

Influence of phosphate and iron on the extent of calcium carbonate precipitation during anaerobic digestion

The extent to which calcium carbonate deposition in an anaerobic reactor can be reduced by adding inhibitors (phosphate and iron) of calcium carbonate crystal growth was investigated. At several concentrations of the additive, the extent of precipitation was assessed in continuous experiments with laboratory‐scale reactors. In the reactor, phosphate concentrations as low as 0.5–5 mg total‐P dm⁻³ were found to severely inhibit CaCO₃ precipitation. However, iron did not inhibit the deposition of CaCO₃, which was found to be due to the fact that iron, in contrast to phosphate, only inhibits the growth of calcite and not the formation of aragonite. The results led to the conclusion that only additives which inhibit the formation of both aragonite and calcite can be used as effective inhibitors during anaerobic digestion. A chemical equilibrium model was developed and shown to be a useful tool to calculate the extent of calcium carbonate deposition during anaerobic digestion provided the proper apparent solubility product of calcium carbonate can be estimated. © 1999 Society of Chemical Industry     

Ion‐exchange adsorption of calcium ions from water and geothermal water with modified zeolite A

The modified zeolite A was prepared by a two‐step crystallization method to remove scale‐forming cations from water and geothermal water. The adsorption kinetics, mechanism and thermodynamics were studied. The calcium ion adsorption capacity of the modified zeolite A was 129.3 mg/g (1 mg/g = 10^?3 kg/kg) at 298 K. The adsorption rate was fitted well with pseudo‐second‐order rate model. The adsorption process was controlled by film diffusion at the calcium ion concentration less than 250 mg/L (1 mg/L = 10^?3 kg/m³), and it was controlled by intraparticle diffusion at the concentration larger than 250 mg/L. The calculated mass‐transfer coefficient ranged from 2.23 × 10^?5 to 2.80 × 10^?4cm/s (1 cm/s = 10^?2m/s). Dubinin–Astakhov isotherm model could appropriately describe the adsorption thermodynamic properties when combined with Langmuir model. The adsorption process included not only ion exchange but also complexation between calcium and hydroxyl ions. The adsorption was spontaneous and endothermal. The high adsorption capacity indicates that the modified zeolite A is a suitable adsorption material for scale removal from aqueous solution. © 2014 American Institute of Chemical Engineers AIChE J, 61: 640–654, 2015     

换热壁面碳酸钙吸附与脱水行为的分子动力学

碳酸钙污垢具有较高的热阻,换热壁面碳酸钙的沉积会导致换热器效率显著下降,因此,换热壁面碳酸钙的形成机理与抑制是换热器设计研究的重点。本文采用分子动力学方法模拟分析过饱和溶液中碳酸钙在高温铜金属壁面上的吸附与脱水行为。模拟结果表明,在碳酸钙向壁面吸附过程中Ca—C配位数先增加后趋近于定值,离子的水合数先减少后趋近于定值。吸附在金属壁面的碳酸钙内部结构未发生明显变化,碳酸钙为具有一定水合数的非晶体结构。壁面温度越高,吸附的碳酸钙脱水越完全,Ca—C和Ca—O的配位数越高,高温壁面吸附的碳酸钙从水合结构向无水晶体转化。当壁面温度提高到800K,离子水合数接近于0,Ca—O配位数约为6,与宏观尺度下无水碳酸钙晶体的Ca—O配位数相接近。     

Synthesis of CaCO3 nanoparticles by controlled precipitation of saturated carbonate and calcium nitrate aqueous solutions

Calcium carbonate nanoparticles (CCNP) were synthesised by precipitation from saturated sodium carbonate and calcium nitrate aqueous solutions. The effect of agitation rate, mixing time, calcium/carbonate ions concentration and temperature on particle size and morphology were investigated. Particles were characterised using X‐ray diffraction (XRD), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). Increasing the mixing time from 30 to 180 min resulted in a decrease in particles size. Mixing rate variation between 300 and 14 000 rpm decreased the particle size. Temperature increase favoured a significant growth in particle size and in the formation of aragonite beginning from 80°C. Calcium and carbonate ion concentrations are key parameters controlling the CCNP particle size. Calcite is the main polymorph obtained as revealed by XRD analysis. © 2011 Canadian Society for Chemical Engineering     

硫酸钙晶体自发沉淀动力学研究

建立了精确测量硫酸钙过饱和溶液在析晶过程中所有离子浓度变化的实验一计算系统。通过测定临界时间与过饱和度之间的关系,得到硫酸钙晶体的表面自由能为21.5mJ/m^2。基于热力学基本理论和经典的沉淀动力学理论,从实验测定值进一步推导出一系列临界状态时的热力学常数。无量纲时间指标Id与时间之间良好的线性关系表明：硫酸钙的析晶过程主要受扩散机制控制。     

反溶剂沉淀法制备阿托伐他汀钙微粉

采用反溶剂沉淀法制备阿托伐他汀钙微粉,考察了表面活性剂类型、药物溶液浓度、体系温度和干燥方法对颗粒形貌和大小的影响,得到了适宜的微粉化条件。实验分别利用扫描电镜（SEM）、X射线衍射（XRD）、红外光谱分析（FT-IR）和比表面积（BET）等分析方法对原料及产品的性质进行了表征。研究结果表明：表面活性剂甲基纤维素（MC₂₀）可以有效地控制颗粒形貌;改变溶液浓度及体系温度可以调整颗粒大小;混悬液经喷雾干燥得到的干粉是粒度分布均匀的团粒状类球形颗粒,粒径约为1 μm。微粉化产品为无定形,比表面积高于原料药。此外,还探讨了团粒状类球形颗粒的形成机理。     

碳酸钙晶须表面改性研究

采用几种改性剂对碳酸钙晶须进行了表面改性试验,结果表明硬脂酸钠对碳酸钙晶须的改性效果显著,以硬脂酸钠为改性剂,考察了改性剂用量、改性时间、改性温度、初始料浆质量分数、搅拌速度、烘干温度等因素对碳酸钙晶须表面改性的影响,选择活化指数及接触角对碳酸钙晶须的改性效果进行表征,在最佳试验条件下,改性产品的活化指数为100%,接触角为146.66°.碳酸钙晶须改性前后的IR检测分析表明,硬脂酸钠改性碳酸钙晶须过程中,在硬脂酸钠与碳酸钙晶须间存在化学吸附.     

鸡蛋壳基多孔碳酸钙对刚果红吸附特性研究

以废弃物鸡蛋壳为原料,以十二烷基硫酸钠为模板剂,采用模板法制成多孔碳酸钙微粒,并用扫描电镜对其进行表观形貌分析。将多孔碳酸钙微粒应用于刚果红的吸附研究,得出较佳吸附条件为：室温、多孔碳酸钙添加量为0.15 g、质量浓度为300 mg/L 的刚果红溶液25 mL、吸附时间为7 h,该条件下的吸附率约为93%。通过吸附等温模型和动力学模型分析,表明多孔碳酸钙对刚果红的吸附属于单分子层吸附,吸附动力学比较符合准二级动力学;红外光谱分析表明多孔碳酸钙对刚果红的吸附主要以物理吸附为主。     

Phosphorus supplying capacity of heavily fertilized soils I. Phosphorus adsorption characteristics and phosphorus fractionation

Studies were conducted to investigate the P sorption characteristics and P fractions in eight intensively fertilized soils collected from southern and central Norway. Adsorption of P at the initial P concentrations in the soil solution was very high in the Særheim clay loam soil which contained high amounts of organic C and clay. Adsorption data were fitted well to the classical Langmuir equation. The P affinity constant (k), adsorption maximum (b) and maximum buffer capacity (mbc) calculated from this equation differed considerably among soils. The P affinity constant (r=0.96,p=0.01) and maximum buffer capacity (r=0.97,p=0.01) were highly and positively correlated to organic C. None of the soil parameters were related to adsorption maximum. Phosphorus desorption from the heavily fertilized soils varied widely and depended on the initial P status of the soil and soil texture. The ratio between desorbed P and total P was significantly correlated to sorption parameters. Multiple regression analysis showed that total P positively and organic C negatively affected P desorption in the soils. Iron-P was a major P sink in these soils and it was related to clay content (r=0.69,p=0.1) and organic P (r=0.76,p=0.0.5), but it did not relate to average P removed per harvest (RPH). Calcium-P and Al-P were not related to any of the soil parameters but these fractions were the major contributors to RPH as expressed by a multiple regression equation: RPH=0.397+0.0016 × Ca-P + 0.0012 × Al-P (r=0.84,p=0.05). High content of inorganic fractions shows that most of the residual P may be plant available, albeit at reduced rate with time, in these soils but the availability will depend on soil types.     

Adsorption of Cd(II) ions at the hydroxyapatite/electrolyte solution interface

The study of the Cd(II) ions adsorption at the hydroxyapatite/electrolyte solution interface and the changes of the electrical double layer (EDL) structure in this system are presented. The adsorption of Cd(II) ions was calculated from the loss of their concentration from the solution using the radioisotope method. The adsorption was studied in the range of the initial concentration from 0.000001 to 0.001mol/dm³ and as the function of pH. The results of measurements of Cd(II) ions adsorption kinetics on hydroxyapatite were fitted using the pseudo-first, pseudo-second, and multiexponential modes to check which model describes this process in the best way. In addition, the main properties of the EDL, i.e., surface charge density and zeta potential were determined by the potentiometeric titration and electrophoresis measurements, respectively. The adsorption of Cd(II) ions at hydroxyapatite contributed to the increase of the zeta potential and also to the change of the double electrical layer structure.     

层状复合金属氢氧化物对硫酸根离子等温吸附和动力学研究

通过共沉淀法制备了镁铝型层状复合金属氢氧化物和镁铝铁型层状复合金属氢氧化物及其焙烧产物(CLDH-Mg/Al和CLDH-Mg/Al/Fe),研究了其结构组成、等温吸附和动力学性质。结果表明:Fe3+的引入增加了表面正电荷,降低了层间间距,加快了层状复合金属氢氧化物初期吸附硫酸根的速度,但降低了达到吸附平衡时的吸附量。无论是镁铝型复合金属氢氧化物还是镁铝铁型复合金属氢氧化物,吸附过程均满足Langmuir吸附等温模型,Fe3+的引入使拟合的最大吸附量降低了19.7 mg/g左右。动力学均符合准二级动力学模型,Fe3+的引入降低了反应速率。     

葡聚糖对烟道气饱充蔗糖钙过程的机理研究

制糖行业是涉及国计民生的重要行业。污染排放已成为影响中国甘蔗制糖业生存与可持续发展的瓶颈问题。采用现代先进的FBRM、SEM、IR和XRD等仪器,观察和分析研究葡聚糖相对分子质量对模拟烟道气饱充蔗糖钙生成的碳酸钙的影响：随着葡聚糖相对分子质量的增加,碳酸钙颗粒形状从分叉钟乳石状变为不规则状;碳酸钙颗粒的弦长范围和不加权中位数弦长,都随着葡聚糖相对分子质量的增大而减小;葡聚糖不引起方解石型碳酸钙晶格的变化。研究结果可为实现制糖产业的绿色加工和节能减排提供理论和技术依据。     

生物质水解发酵废水中钙离子的去除研究

采用二氧化碳与助剂A联合法对生物质水解发酵废水中Ca~(2+)的去除进行了研究.研究表明.在助剂A的作用下,pH为9～10时,对Ca~(2+)的去除效果较好,去除规律符合线性相关.同时.体系中的碳酸氢盐碱度和总碱度增长较大,为后续厌氧处理提供了良好的条件.     

钙盐沉淀法处理草甘膦母液的试验研究

甘氨酸法合成草甘膦的过程中会产生草甘膦母液,对采用钙盐沉淀法处理草甘膦母液进行了单因素试验研究.试验结果表明:钙盐投加量、沉淀pH、搅拌时间、搅拌速度、静置时间等对沉淀反应均有影响.当钙盐投加质量浓度为0.06 kg/L,沉淀母液pH=9,搅拌时间为1.0 min,搅拌速度为150 r/min,静置时间为40 min时...