脱乙酰甲壳质和卡拉胶的稀溶液反应

本文研究了脱乙酰甲壳质和卡拉胶为稀溶液时的电离及两者之间的相互作用。卡拉胶在溶液中呈强酸型聚电解质行为,而脱乙酰甲壳质呈弱碱型聚电解质行为并随脱乙酰度提高而碱性下降。脱乙酰甲壳质和卡拉胶的稀溶液反应生成不溶于水的白色沉淀。浊度测量显示,在pH值低于4时,反应是化学计量的,说明这时它们之间的反应主要是通过静电相互作用而形电解质复合物沉淀。当pH值较高时,反应偏离化学计量结果。

基于湖积物硅藻与地球化学记录的古环境变迁反演——以桂林会仙岩溶湿地为例

通过对狮子潭柱状沉积物的放射性定年、地球化学与硅藻分析,反演桂林会仙岩溶湿地全新世的古湖沼演替,与其响应的气候变迁与人类活动记录。放射性^(210)Pb、^(14)C定年结果显示该湖在6 400 cal BP开始有湖积物保存,在2 700 cal BP—公元1943年间有沉积间断事件,且于公元1943年再度沉积。在6400—5 200 cal BP,高比例的浮游型硅藻反映高水位状态,可对应到气候暖湿的中国全新世大暖期鼎盛期。在5 200—2 700 cal BP,沉积物内稀酸可溶相Ca、Mg、Sr浓度降低,Mg/Ca、Sr/Ca值明显增加,且浮游型硅藻几乎消失,显示当时湖泊水位显著降低,气候逐渐变干。在公元1943年沉积物再度沉积,可能与战争造成人口迁徙与废耕有关。自公元1973年以来,硅藻壳片大量堆积,反映人类过度活动造成藻华的现象。湖泊沉积物内硅藻组成及沉积物的地球化学特征能够很好地反演古气候、环境变迁。

三峡水库对大宁河沉积环境的影响--碳酸盐和常量元素含量的变化

对2006年10月采自长江巫山段一级支流大宁河河底的三根岩芯作了常量元素(K、Na、Ca、Mg)的分析。研究结果表明,沉积物中稀酸可溶相常量元素的含量能够反映沉积物的特征和来源。大宁河中—上游沉积物中碳酸盐含量平均为23%,反映岩溶地区石灰岩风化的影响;而与长江交接处的沉积物中碳酸盐含量平均为10%,显示长江主流有明显不同的沉积物来源。三峡大坝的建成蓄水,水位提高,使得碳酸盐含量低的红色粘土进入双龙镇段大宁河沉积,造成碳酸盐含量、稀酸可溶相常量元素含量急剧下降、沉积物的颜色发生显著变化。受到蓄水作用的影响,大宁河泥沙沉积速率大幅度提高,自2004年12月蓄水以来,大宁河双龙镇附近沉积物厚达10cm以上。

美国西部Owens湖地球化学记录及其古气候意义

美国加州中部Owens湖的稳定同位素、稀酸可溶相锂元素浓度及其它地球化学指标揭示本区 0 .15 5MaB .P .～ 6 2 5 0 0aB .P .间的气候变化。在 0 .15 5～ 0 .14 0MaB .P .,0 .12 2～0 .114MaB .P .,910 0 0～ 830 0 0aB .P .和 72 0 0 0～ 6 2 5 0 0aB .P .期间 ,气候冷湿 ,对应于深海氧同位素 (MIS) 6 ,5d ,5b和 4阶段。这些期间内湖泊开放 ,δ18O和δ13 C无协变性 ,Li和有机碳浓度很低。在 0 .14 0～ 0 .12 2MaB .P .,0 .114MaB .P .～ 910 0 0aB .P .和 830 0 0～ 72 0 0 0aB .P .期间 ,气候干热 ,对应于MIS5e ,5c和 5a阶段。湖泊在这些期间内封闭 ,δ18O和δ13 C有很好的协变性 ,封闭湖δ18O的变化代表了湖水体积的变化。来自湖中自生镁硅酸盐的锂元素浓度的变化反映了盐度和温度的变化。Owens湖的记录与DevilsHole洞穴流石记录和格陵兰冰芯记录有很好的对比 ,进一步证实了终结期Ⅱ在海相记录中的年龄滞后。本文讨论了冰期与间冰期之间 ,美国西部和中国黄土地区气候模式的差异及其互动机制。

Photocatalytic Degradation of Water-Soluble Dyes by LaCoO_3

Pervoskite type oxides LaCoO 3 was prepared by citrate method with the granula of 20 nm-30 nm. With a fluorescent Hg lamp or sunlight as irradiator, the degradation experiments of various water soluble dyes were carried out in the suspension system of LaCoO 3 . The results show that the pervoskite type oxide LaCoO 3 has good photocatalytic activity.Studied by X ray photoelectron spectroscopy and photoacoustic spectra, its photocatalytic activity is found to be related with factors such as the d electron structure of ion Co 3+ ,Co—O binding energy and adsorbed oxygen on the surface etc.

Uncertainty Evaluation of Preparation of Organophosphorus Pesticide Mixed Standard Solution

The uncertainty of standard solution plays an important role in detection of pesticide residues. It may affect the accuracy of detection results. In this study, the 14 organophosphorus pesticides mixed standard solution was used as the material to analyze all the influencing factors for the preparation of mixed standard solution with uncertainty as the only judging index. The preparation uncertainty of mixed standard solution was calculated with the top-down calculation method. In the end, the expanded uncertainty was presented. The results showed that the preparation of mixed standard solution from stock solution with precise pipettes had a relatively low uncertainty.

Photocatalytic Degradation of Water-Soluble Dyes by LaCoO3

Pervoskite type oxides LaCoO 3 was prepared by citrate method with the granula of 20 nm-30 nm. With a fluorescent Hg lamp or sunlight as irradiator, the degradation experiments of various water soluble dyes were carried out in the suspension system of LaCoO 3 . The results show that the pervoskite type oxide LaCoO 3 has good photocatalytic activity.Studied by X ray photoelectron spectroscopy and photoacoustic spectra, its photocatalytic activity is found to be related with factors such as the d electron structure of ion Co 3+ ,Co—O binding energy and adsorbed oxygen on the surface etc.

Removal of Phenol from Dilute Solutions by Predispersed Solvent Extraction

Predispersed solvent extraction (PDSE) is a new method for separating solutes from aqueous solution by solvent extraction and one which has shown promise for extraction from extremely dilute solution very efficient and very quick. The use of colloidal liquid aphrons in predispersed solvent extraction may ameliorate the problems such as emulsion formation, reduction of interfacial mass transfer and low interfacial mass transfer areas in solvent extraction process. In present paper, colloidal liquid aphrons are successfully generated using kerosene as a solvent, tributyl phosphate(TBP) as an extractant, sodium dodecyl benzene sulphate(SDBS) as surfactant in aqueous phase and Tween-80 in oil phase. Extraction of phenol from dilute solution was studied by using colloidal liquid aphrons and colloidal gas aphrons in a semi-batch extraction column. It has been found that the PDSE process is more suitable for extraction of dilute solutions. It has also been discovered that the PDSE process has a great advantage over traditional single-stage extraction process.

Removal of β-Naphthalenesulfonic Acid from Aqueous Dilute Solution Using Bagasse Fly Ash

Bagasse fly ash was converted into an inexpensive adsorbent andutilized for the removal of β- naphthalenesulfonic acid in dilutesolution. The effect of pH, temperature, adsorbent concentration, andco-existed acids on the removal of β-naphthalenesulfonic acid wasexamined. The adsorption data have been correlated with both Langmuirand Freundlich adsorption models. Thermodynamic parameters obtainedindicate the feasibility of the process, and kinetic studies providedthe necessary mechanistic information of the removal process.

Recovery of iron and rare earth elements from red mud through an acid leaching-stepwise extraction approach

A feasible approach to selectively recover iron and rare earth elements(REEs)from red mud through acid leaching-coordination-solvent extraction was proposed.The leaching efficiencies of Fe,Al,Ti,Sc,La,Ce,Nd and Y can reach up to 95.9%,82.1%,68.3%,93.3%,82.3%,96.9%,98.3%and 95.6%,respectively,under the optimal condition in the leaching process.Aliquat 336 showed excellent extraction performance of iron in chloride-rich solution,and the maximum extraction efficiency can reach over 96%in one time extraction while the loss of other metals was less than 10%,under the condition of Aliquat 336 concentration(v/v)of 30%,aqueous-organic ratio of 1.0 and extraction time of 20 min.Furthermore,P204 can effectively extract the scandium while Al and most other REEs remain in the aqueous phase.This approach may provide a new insight for the recovery of valuable resources from red mud.

Solubility of trans-1,2-Cyclohexanediol in Some Solvents

The solubility of trans-1,2-cyclohexanediol in water, methyl acetate, acetic ester, propyl acetate, butyl acetate, methyl acrylate, ethyl acrylate, 2-pentanone and acetoacetic ester was measured at temperatures ranging from about 300 K to 330 K, using a modification of the experimental technique of laser monitoring observation system. The solubilities were calculated by λh method, in which new parameters were introduced to express the activity coefficients of trans-1,2-cyclohexanediol, and determined from the experimental data. The new parameters provide good calculated results. The experimental data were also correlated with a simple model, and results were compared with present λh model.

Recovery of Dyestuffs from Dilute Solution with Two-phase Electrophoresis

Two-phase electrophoresis was used to separate the dyestuffs from their dilute solutions. Several dyestuffs (naphthol green B, acid-chrome blue K, methyl blue and direct fast torquoise blue GL, and n-butanol) were treated in a self-designed experimental setup and the mass transfer characteristics in this process were studied. The results confirm the potential of this technique for recovering dyestuffs from their dilute solutions.

Dissolution behaviors of rare earth elements in phosphoric acid solutions

In order to provide practical fundamental data for rare-earth elements （REEs） recovery from phosphoric acid and to betterunderstand REEs behavior during the phosphoric acid evaporation process, the solubilities of REEs in phosphoric acid with variousconcentrations of phosphorus at different temperatures were measured. A simple linear model between REEs solubility andphosphoric acid concentration is built and the experimental data are found to fit it very well （R2〉0.94）. Hydrogen-ion concentration isfound to be the predominant factor controlling the solubility of REEs in phosphoric acid. In addition, the solubility of REEs inphosphoric acid is found to sharply decrease with increasing temperature, which can be attributed to the increase of the Gibbs energyof the REEPO4 dissolution reaction or the restraint of the disassociation of phosphoric acid molecules owing to the elevatedtemperature.

Anti-UV Capability of Rare Earth Doping TiO_2

The sol-gel process is used in the preparation of nanostructure materials with Ti(OC_ 4 H_ 9 )_ 4 as precursor in the start materials. TiO_ 2 gelatin is obtained through hydrolysis and condensation process. Rare earth such as La_ 2 O_ 3 , CeO_ 2 , Eu_ 2 O_ 3 and Gd_ 2 O_ 3 are introduced into the nanostructure TiO_ 2 to improve the anti-UV capacity. The phase structure of pure TiO_ 2 and doped TiO_ 2 and their anti-UV capacity are studied by means of XRD and UPF. The optimum doping and heat treatment temperature are chosen.

Maximizing the exploitation of phosphogypsum wastes using soaking technique with citric acid, recovering rare-earth and residual phosphate contents

Phosphogypsum(PG), the main by-product of phosphoric acid production industries, is considered one of the most important secondary sources of rare earth elements(REEs). The current study focuses on the recovery of REEs content and the residual phosphate content existing in the PG with preserving on the CaSO_(4)skeleton to be used in other various applications. These attainments are carried out using citric acid leaching process via soaking technique. Several dissolution parameters for REEs using citric acid were studied, including soaking time, soaking temperature, citric acid concentration, solid-to-liquid ratio, and recycling of the citrate leaching solutions in the further REEs dissolution experiments. The best-operating conditions were 14 d of soaking time, 7.5% citric acid concentration, and the solid-toliquid ratio of 1/5 at ambient temperature. About 79.57% dissolution efficiency of REEs was achieved using the optimal conditions. Applying four soaking stages by mixing different fresh PG samples with the same citrate solution sequentially, cumulative dissolution efficiency for REEs was found to be 64.7% under optimal soaking conditions. REEs were recovered using Dowex 50X8 resin from citrate solutions with 96% extraction efficiency. Dissolution kinetics proved the pseudo-first-order nature, reversible reactions, and two activation energies for all REEs.

Effect of Lanthanum Accumulation on Cation Exchange Capacity and Solution Composition of Red Soil

Pot and adsorpt ion- exchange experiments were carried out by collecting the soil samples from the surfacelayer (0~15 cm) of red soil at the Ecological Experiment Station of Red Soil, the Chinese Academy of Sciences,in Jiangxi Province of China. When concentration of the exogenous La3+ exceeded 400 mg kg-1, therewas less non-exchangeable La3+ than exchangeable La3+ in the soil. Cation exchange capacity of the soilchanged slightly with increasing concentration of the exogenous La3+ in both experiments. However, in theadsorption-exchange experiment, when concentration of the exogenous La3+ was higher than 3Oo mg kg-1 ,exchangeable basic cations decreased significantly, while exchangeable hydrogen and exchangeable aluminumincreased significantly compared with the control treatments. The amounts of base cations (Ca2+ ) Mg2+, K+and Na+) exchanged by La3+ in the supernatant solution increased with the concentration of the exogenousLa3+, especially when concentration of the exogenous La3+ was higher than 50 mg kg-1.

Dynamics of vascular volume and hemodilution of lactated Ringer’s solution in patients during induction of general and epidural anesthesia

Objective： To investigate the dynamics of vascular volume and the plasma dilution of lactated Ringer＇s solution in patients during the induction of general and epidural anesthesia. Methods： The hemodilution of i.v. infusion of 1000 ml of lactated Ringer＇s solution over 60 min was studied in patients undergoing general （n=31） and epidural （n= 22） anesthesia. Heart rate, arterial blood pressure and hemoglobin （Hb） concentration were measured every 5 rain during the study. Surgery was not started until the study period had been completed. Results： General anesthesia caused the greater decrease of mean arterial blood pressure （MAP） （mean 15% versus 9%; P〈0.01） and thereby followed by a more pronounced plasma dilution, blood volume expansion （VE） and blood volume expansion efficiency （VEE）. A strong linear correlation between hemodilution and the reduction in MAP （r=-0.50;P〈0.01） was found. At the end of infusion, patients undergoing general anesthesia retained 47% （SD 19%） of the infused fluid in the circulation, while epidural anesthesia retained 29% （SD 13%） （P〈0.001）. Correspondingly, a fewer urine output （mean 89 ml versus 156 ml; P〈0.05） and extravascular expansion （454 ml versus 551 ml; P〈0.05） were found during general anesthesia. Conclusion： We concluded that the induction of general anesthesia caused more hemodilution, volume expansion and volume expansion efficiency than epidural anesthesia, which was triggered only by the lower MAP.

Separation of Lactic Acid from Diluted Solution by Hybrid Short Path Evaporation and Reactive Distillation

This work describes the separation and purification of lactic acid from diluted solution by HSPE （hybrid short path evaporation） and RD （reactive distillation） as coupled process. The results showed that it is possible to increase lactic acid concentration up to 4.7 times higher than the raw material concentration.

Simulation of one-dimensional column leaching of weathered crust elution-deposited rare earth ore

The ion exchange model of the leaching process was determined via batch leaching experiments using the Kerr model, with the selectivity coefficient experimentally determined to be 12.59×10^-10 L^2/g^2. Solute transport laws of ammonium ions (NH4 +) and rare earth ions (RE^3+) in column leaching were described by the convection-dispersion equation (CDE). The source and sink in the CDE were determined by the Kerr model. The CDE with strong nonlinearity was solved using the sequential non-iterative method. Compared with the breakthrough curve of RE^3+, the correlation coefficient between the simulated and experimental curves reached 0.8724. Therefore, this method can simulate the one-dimensional column leaching of weathered crust elution-deposited rare earth ore. Moreover, the effects of different concentrations of ammonium sulfate ((NH4)2SO4) solution on the leaching rate of rare earth were analyzed. The optimal concentration of the (NH4)2SO4 solution had a linear relationship with the rare earth grade.

Synthesis and Characterization of Titania and Rare Earth Doped Titania Nanoparticles by Sol-gel Process

Titania sol has been prepared by the sol-gel process with Ti（OC4H9）4, as precursor. TiO2 gel was obtained through hydrolysis and condensation process. Rare earth such as La2O3, CeO2 and Gd2O3 were introduced into the nanostructure TiO2. After TiO2 and rare earth doped TiO2 powders were calcined at 400℃, 500℃, 600℃, 700℃ and 800℃ respectively, the characteristic analyses of the TiO2 samples were studied by UV-VIS, XRD and TEM etc. It was found that there are some stringer absorption peaks at 200 - 325 nm. The rare earth doping can increase the phase transition temperature convertin8 anatase phase into rutile phase, can decrease the grain size of TiO2particles and can improve the ann-UV capacity of the coating fabrics.