红外法测定稀土金属及氧化物中碳硫

介绍高频红外法测定稀土金属和氧化物中碳硫量的一种快速，灵敏方法，并对试样制备，处理和保存条件作了探讨，对助熔剂，分析时间及称样量作了较详细的研究，获得最佳条件，测定结果的ＲＳＤ碳〈１．３％，硫〈１．８％。     

稀土对红壤微生物量碳的影响

取过２０ 目筛黄筋泥（浙江龙游县, 桔园表层土,ｐＨＨ２０ 为５．１,有机质含量为２．３５％ , 每１００ ｇ 土的阳离子交换量为１０．５０ ｍｍｏｌ, 每１ ｋｇ 土的可溶态稀土总量为１１．４４ ｍｇ） 风干土若干, 以０,１０,５０,１００,２００,３５０ ｍｇ·ｋｇ－１的浓度水平分别加入混合稀土及单一稀土元素Ｐｒ,Ｓｍ ,Ｅｕ 等, 混合稀土的配比为Ｌａ∶Ｃｅ∶Ｐｒ∶Ｎｄ∶Ｓｍ∶Ｅｕ∶Ｇｄ∶Ｙ＝４∶４∶２∶２∶２∶１∶１∶４, 并对土样加蒸馏水至田间持水量的５０％ , 保持１００％ 的湿度在生化培养箱中于２５ ℃下恒温培养一周后进行微生物量的测定, 每个样重复３ 次, 土壤样品微生物量碳的测定方法采用氯仿熏蒸,０．５ ｍｏｌ·Ｌ－１ Ｋ２ＳＯ４ 提取法, 提取液中的有机碳浓度用自动定碳仪（ＴＯＣ）测定, 并由下式计算微生物量：ＳＭＢＣ＝ （ｃＥＣｔ－ ｃＥＣＯ）／０．４５, 式中,ＳＭＢＣ为土壤微生物量碳,ｃＥＣＯ,ｃＥＣｔ分别为氯仿熏蒸前后提取液中有机碳的浓度。测定结果表明, 不同稀土元素对土壤熏蒸前后的有机碳含量及其微生物量碳变化的影响规律基本相似, 随着稀土浓度的升高,熏蒸前后有机碳的含量都有不同程度的升高, 而且两者在量值上有逐渐     

红外碳硫测定仪测定铁矿石中硫

采用红外碳硫仪对铁矿石中硫进行测定，通过对助熔剂各类、助熔剂的加入量，助熔剂的比例，称样量、试样加入顺序等条件进行试验，选择了测定铁矿石中硫的最佳条件，此法的测定范围为0．01％－4．0％。     

高钛渣中碳和硫自动快速测定

以电弧炉引燃钢铁合金试样,非水滴定法或气体容量法测定碳量,碘量法测定硫量己广泛应用,但用于高钛渣中碳硫测定未见报道。本方法成功地用于生产分析,对高钛渣及炉渣测量范围,碳为0.1—2.0％;硫为0.05—0.20％。仪器及试剂 HB-B型自动电弧炉;HV-1型碳硫高速自动分析仪。40％KOH溶液;1/1000H_2SO_4的酸性水溶液(加数滴红墨水);4g/5000mL淀粉水溶液(加浓盐酸50mL);0.05mol/L碘酸钾溶液(1.78g碘酸钾溶于1000mL水中),根据硫含量范围,取30mL或60mL此溶液以水稀释至1000mL使之与试样中硫含量相适应。分析步骤按仪器说明书进行气密性检查,调节     

Co-Mo/HZSM-5甲烷无氧芳构化催化剂上的积炭

 考察了Co－Mo／HZSM－5催化剂对甲烷芳构化反应的催化性能及催化剂上的积炭．采用碳数平衡计算法和TG法得出的平均积炭速率比较接近,在不同空速下,360min内,催化剂上的积炭量都接近5％．对烧炭TG曲线的分析结果表明,积炭量约为5％时,积炭能分散于分子筛表面．在高空速下,积炭容易沉积在分子筛的外表面;在低空速下,积炭容易沉积在分子筛的内表面．在空速3000ml／（g·h）下积炭时,其烧炭动力学过程符合一级反应过程,烧炭活化能为140．8kJ／mol．     

应用微分电位溶出法测定固体食品中的铅

以0．16moL／LHNO3为底液．预镀汞膜的玻碳电极为工作电极，用微分电位溶出法对固体食品中的铅进行测定，用标准加入法定量。检出限2．5×10－9，变异系数0．7％～5．7％，回收率93％～106％，本法与原子吸收法对比，测定结果无显著性差异．     

微分电位溶出法测定车间空气中镉的研究

以０．５０ｍｏｌ．Ｌ＾－１盐酸为底液，预镀汞膜的玻碳电极为工作电极，用微分电位溶出法对车间空气中镉进行测定，用标准加入法定量，在选定的条件下，线性关系良好，精密度ＣＶ为１．２５６％－２．２３％，平均回收率为９６％－１０７％，本法与原子吸收法对比，测定结果显著性差异，结果令人满意。     

以稀酸和氟化物两步处理脱除石墨中矿物质

选用三种天然磷片石墨（大同混目石墨固定碳含量为８８．７８％，内蒙古兴和混目石墨固定碳含量为９５．６７％，山西芮城－１８５石墨固定碳含量为８６．４７％），在不同的条件下，用稀酸和氟化物溶液进行处理，考察了它们脱除矿物质的作用。经１００℃用稀酸溶液处理２ｈ，然后用氟化物溶液在７０℃左右处理２．５ｈ，大同混目石墨固定碳含量可达９９．９３％，内蒙兴和混目石墨固定碳含量可达９９．８０％，芮城－１８５石墨固定     

科学家研制出高载负量、高荧光亮度碳纳米点

<正>近期,中科院长春光机所曲松楠团队首次研制出高载负量、高荧光亮度的碳纳米点@二氧化硅复合凝胶。该工作利用碳纳米点表面大量的羟基官能团引发正硅酸乙酯水解,在碳纳米点表面原位包覆二氧化硅。在高浓度的碳纳米点乙醇溶液中,实现具有高载负量、高荧光亮度的碳纳米点@二氧化硅复合凝胶,并可进一步获得荧光效率高达41%的干凝胶粉体材料,在开发基于碳纳米点的发光器件领     

稀土在铁基高铬合金粉末球磨过程中的作用

在铁基高铬合金粉末球磨体系中加入一定量的稀土元素及其氧化物,当稀土元素铈的含量达到０．４％－０．６％时,球磨以后活性氧的去除量达到最大值,附加一定量的稀土氧化物有利于脱氧;通过热力学分析得出：稀土元素在机械球磨过程中可以将粉料体系中的大部分氧化物还原,起到保碳的作用。     

1-偶氮苯-3-(6-甲氧基-2-苯并噻唑)-三氮烯光度法测定粉煤灰中微量锌

研究了1-偶氮苯-3-(6-甲氧基-2-苯并噻唑)-三氮烯(AMBT)与锌的显色反应,在pH11.0的Na2CO3-NaHCO3缓冲溶液中,TritonX-100存在下,AMBT与Zn(Ⅱ)反应生成2∶1稳定络合物,其最大吸收波长为535nm,表观摩尔吸光系数为8.37×104L.mol-1.cm-1。锌质量浓度在0~0.40μg/mL内符合比尔定律,方法用于测定粉煤灰中微量锌,结果与极谱法相符,RSD<3%。     

CO_2 absorption with ionic liquids at elevated temperatures

CO_2 capture with ionic liquids(ILs) has attracted many attentions, and most works focused on absorption ability at ambient temperatures, while seldom research was concerned at elevated temperatures.This not only limits the CO_2 absorption application at elevated temperature, but also the determination of the operation condition of the CO_2 desorption generally occurring at higher temperature. This work mainly reported CO_2 solubilities in ILs at elevated temperatures and related properties were also provided. 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide([CnMIm][Tf_2N]) ILs were selected as physical absorbents for CO_2 capture in this work due to their relative higher CO_2 absorption capacities and good thermal stabilities. The long-term stability tests showed that [CnMIm][Tf_2N] is thermally stable at 393.15 K for long time. CO_2 solubilities in [CnMIm][Tf_2N] were systematically determined at temperatures from 353.15 K to 393.15 K. It demonstrated that CO_2 solubility obviously increases with the increase of pressure while slightly decreases with increase of temperature. As the length of alkyl chain on the cation increases, CO_2 solubility in ILs increases. Additionally, the thermodynamic properties including the Gibbs free energy, enthalpy, and entropy of CO_2 were also calculated.     

CO2/离子液体体系热力学性质的分子动力学模拟

超临界CO2和离子液体(ILs)是两种绿色溶剂. 离子液体可以溶解超临界CO2, 而超临界CO2不能溶解离子液体. 由此设计构成的CO2/IL二元系统, 同时具备了超临界CO2和离子液体的许多优点: 既可以降低离子液体的粘度, 还便于相分离, 是新型的耦合绿色溶剂. 其物理化学性质对于设计反应、分离等过程非常重要. 因此, 本文以CO2/IL二元系统为研究对象, 通过选择合适的分子力场和系综, 运用分子动力学(MD)模拟方法研究了CO2/[bmim][PF6]、CO2/[bmim][NO3]等体系的热力学性质. 结果表明, CO2对ILs膨胀度的影响非常小, 当CO2摩尔分数为0.5时, ILs膨胀仅为15%. CO2/ILs的扩散系数远小于CO2膨胀甲醇、乙醇溶液的扩散系数. 随着CO2含量的增加, ILs的扩散系数提高, 粘度显著下降, 表明CO2能有效地改善ILs扩散性, 减小其粘度. 因此CO2可用以改善离子液体溶剂体系的传递特性, 增强反应分离过程在其中的进行.     

色谱法同时测定羰化反应尾气中的O2、CO、CO2

提出用特制活性炭填充柱分离,热导检测器检测,以外标法定量,同时测定O2、CO、CO2.探讨了该方法的校正因子、各组分的线性相关性及微量氧气的分离和定量等.在选定的色谱条件下,O2与CO的分离度达1.7,各组分的相对标准偏差＜0.18%,绝对误差＜0.04%.     

Synthesis of polymeric ionic liquids material and application in CO_2 adsorption

We synthesized one quaternary ammonium polymeric ionic liquids(PILs)P[VBTHEA]Cl and three imidazolium PILs of P[VEIm]Br, P[VEIm]BF_4, P[VEIm]PF_6 by free-radical polymerization in solution. These PILs were characterized by FT-IR,~1 H-NMR,~(13)C-NMR, TGA, XRD and SEM. Their CO_2 adsorption capacities were measured under different pressures and temperatures by constant-volume technique. It was observed that quaternary ammonium PILs of P[VBTHEA]Cl have higher adsorption capacity for CO_2 than those imidazolium PILs, following P[VBTHEA]Cl P[VEIm]PF_6 P[VEIm]BF_4 P[VEIm]Br, which may be ascribed to higher positive charge density on ammonium cation than that on imidazolium cation and thus stronger interaction with CO_2, consistent with the results from dual-mode adsorption model that ammonium PILs have much higher CO_2 bulk absorption than imidazolium PILs. CO_2 adsorption capacity of P[VBTHEA]Cl is 9.02 mg/g under 295 K and 1 bar, which is comparable to that of some other PILs, and is much higher than that of the corresponding ILs monomer. These PILs have good adsorption selectivity for CO_2 over N_2 and regeneration efficiency.     

SYNTHESIS OF LANSFORDITE MgCO_3·5H_2O AND ITS CRYSTAL STRUCTURE INVESTIGATION

Euhedral crystals of the uncommon low-temperature mineral lansfordite have been obtained by the synthetic method, and the crystal structure analysis has been accomplished correspondingly. The structural parameters and the general view of structure were presented for the first time. The results obtained show that the coordination configuration of two magnesium ions in the unit cell is octahedral arrangement and the coordination number is 6, but in two forms: one in the complex ion Mg(CO_3)_2(H_2O)_4~(2-) and the other in the Mg(H_2O)_6~(2+). There is only a CO_3~(2-) group in the structure, not three distinct groups as reported by Hill et al. previously based on the IR absorption spectrum research data. The authors of this paper believe that the exact chemical formula of lansfordite should be expressed as "Mg(H_2O)_6. Mg(CO_3)_2 (H_2O)_4", and MgCO_3-5H_2O is only a simple chemical expression.     

二氧化碳/1,2-环氧丁烷/ε-己内酯的三元共聚合和表征

以高聚物负载型双金属负离子配位化合物PBM为催化剂,通过二氧化碳(CO2),1,2-环氧丁烷(BO)与ε-己内酯(CL)的三元开环共聚合反应,得到三元共聚物,脂肪族聚碳酸酯(PBCL).对PBCL进行了FTIR1、H-NMR1、3C-NMR、DSC和WAXD等表征,并考察了反应单体比例及反应时间对共聚物性能的影响.结果表明,由于ε-己内酯开环共聚,引入了易水解的羧酸酯单元,PBCL的降解速度和玻璃化转变温度较二氧化碳-环氧丁烷的二元共聚物(PBC)得到了有效地提高.同时,PBCL相对于聚己内酯(PCL)玻璃化转变温度和降解速度明显改善,且PBCL为非晶结构.     

用23Na和27Al固体核磁共振研究Na+在γ-Al2O3上的吸附状态

The adsorption of Na~+ on γ-alumina surface at four coverages of Na_2CO_3 (5%, 10%, 15%, and 20% wt/wt) was characterized by solid-state ~(23)Na and ~(27)Al NMR spectroscopy. The experimental results suggest that two distinct adsorbed species are present on alumina surface: surface species and surface salts. At lower coverages of Na_2CO_3 (5% and 10%), a surface species is predominant, in which the Na~+ cations are associated with the oxygen atoms of γ-alumina. With increasing the loading level to 15%, a second adsorbed species begins to appear which is attributed to the surface salt, Na_2CO_3, deposited on the solid surface. Further adsorption of Na_2CO_3 leads to an increase in the amount of surface salt while the amount of surface species remains unchanged. ~1H-~(27)Al CP/MAS experiments give the evidence that some Na~+ cations in the form of surface species are coordinated with the Br~(‥)onsted acid sites of γ-alumina. This may be the main driving force that improves appreciably the catalytic efficiency of Na_2CO_3/γ-Al_2O_3 catalyst.     

液态及超临界CO_2萃取八角茴香油的研究

本文用液态及超临界CO_2对八角茴香油进行了萃取研究，在萃取压力为20．0～25．0MPa的条件下，详细地考察了临界温度上下萃取温度和解析温度对出油率和油的表观相态的影响，结果表明，萃取温度越高和／或解析温度越低出油率越低；用液体CO_2萃取比用超临界CO_2萃取的出油率要高得多；萃取温度大约在318K以下或解析温度在临界温度以下时，萃取所得八角茴香油都有明显分层现象．     

Selective electroreduction of carbon dioxide to formic acid on electrodeposited SnO_2@N-doped porous carbon catalysts

Electrocatalytic reduction of CO_2 is a promising route for energy storage and utilization. Herein we synthesized SnO_2 nanosheets and supported them on N-doped porous carbon (N-PC) by electrodeposition for the first time. The SnO_2 and N-PC in the SnO_2@N-PC composites had exellent synergistic effect for electrocatalytic reduction of CO_2 to HCOOH. The Faradaic efficiency of HCOOH could be as high as 94.1% with a current density of 28.4 mA cm-2 in ionic liquid-MeCN system. The reaction mechanism was proposed on the basis of some control experiments. This work opens a new way to prepare composite electrode for electrochemical reduction of CO_2.