Gel Permeation Chromatography Calibration. I. Use of Calibration Curves Based on Polystyrene in THF and Integral Distribution Curves of Elution Volume to Generate Calibration Curves for Polymers in 2,2,2-Trifluoroethanol

Abstract

A general method is proposed for obtaining gel permeation chromato-graphic (GPC) molecular weight (MW) and hydrodynamic volume (HDV) calibration curves for polymer-solvent systems where primary polymer standards are unavailable. The method is demonstrated by using a HDV calibration curve based on polystyrene in tetrahydrofuran (THF), in conjunction with integral distribution curves of elution volume for poly(methyl methacrylate) (PMMA) in THF and in 2,2,2-tri-fluoroethanol (TFE) for the generation of a HDV calibration curve in TFE. Transformation methods for generating secondary MW calibration curves from HDV calibration curves are discussed and applied to PMMA in THF and TFE, and to poly(trimethylene oxide), poly(vinyl acetate), and certain polyamides in TFE. The utility and reliability of the secondary calibration curves are demonstrated by comparing MW average and intrinsic viscosites obtained by GPC and by the classical methods. Molecular structural differences among th polyamide samples associated with the distribution of short- and long-chain branches are discussed in relation to their secondary calibration curves.     

Synthesis,characterization, and amidoximation of diaminomaleodinitrile-functionalized polyethylene terephthalate grafts for collecting heavy metals from wastewater

Synthesis, characterization, and amidoximation of diaminomaleodinitrile-functionalized polyethylene terephthalate (PET) grafts were studied. Azobisisobutyronitrile (AIBN) was used as an initiator. Optimum conditions for grafting were as follows: monomer concentration [DAMN] = 0.5M, [AIBN] = 1.50 × 10⁻³ mol/L, T = 80°C and t = 3 h. Water uptake of the grafted-PET film increased with the increase of grafting yield. The imparted cyano group of the grafted polymer chains (with degree of grafting up to 83%) was converted into amidoxime group by reaction with hydroxylamine. The unique advantage of this polymer is that it contains double amidoxime groups per repeating unit and an additional diethylene spacer unit between neighboring amidoxime groups in each monomeric unit. The grafted-PET films were characterized by FTIR spectroscopy, differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). The grafted-PET films are more thermally stable than the ungrafted-PET membrane, since the grafted membrane showed a single degradation pattern despite having two components. A decrease in T_g values is observed as the grafting yield of copolymers increases indicating the incorporation of polydiaminomaleodinitrile chains in amorphous copolymers with higher thermal stability. The prepared amidoximated DAMN83-g-PET was investigated for its properties in removing heavy toxic metals, such as Pb²⁺, Cd²⁺, Zn²⁺, Fe²⁺, Cu²⁺, Ni²⁺, Co²⁺, and Ag¹⁺ from waste water. The amidoximated-film is characterized by a considerably greater binding ability with respect to heavy metals. The nature of the metal ion also has great importance in the amount binding to the polymeric material. The kinetics of the sorption/desorption process for Co²⁺, Ni²⁺, and Zn²⁺ are investigated. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Treatment of Contaminated Water Laden with 4-Chlorophenol using Coconut Shell Waste-Based Activated Carbon Modified with Chemical Agents

This laboratory study investigates the performances of coconut shell waste-based activated carbon (CSBAC) in removing 4-chlorophenol (4-CP) from contaminated water. To improve its removal for target compound, the surface of CSBAC was modified with TiO₂, NaOH, and/or HNO₃. Under optimized conditions at the same initial concentration of 25 mg/L, the NaOH-treated CSBAC could remove 91% of 4-CP, compared to the HNO₃-oxidized CSBAC (60%) or the TiO₂-coated CSBAC (72%). Although the NaOH-treated CSBAC could remove 91% of 4-CP, the adsorption treatment using this adsorbent alone was unable to meet the effluent limit of lower than 1 mg/L. Therefore, subsequent biological processes are required to complement the removal of 4-CP from wastewater.     

不同吸附剂对白酒异嗅物质去除的研究

实验对比了三大类共27种吸附剂对白酒中的16种异嗅物质（4-甲基苯酚、4-乙基苯酚、4-乙烯基苯酚、苯酚、愈创木酚、4-甲基愈创木酚、4-乙基愈创木酚、4-丙基愈创木酚、4-乙烯基愈创木酚、土味素、2-庚醇、3-辛醇、1-辛烯-3-醇、1-辛烯-3-酮、反式-2-辛烯-1-醇、反式-2-壬烯醛）的去除情况。采用浸入式固相微萃取（DI—SPME）结合气相色谱-质谱联用（GC—MS）技术对处理前后的酒样进行快速检测,计算其去除率。结果发现树脂的去除效果优于凹凸棒土、硅藻土、皂土和酒用活性炭,其中大孔阴离子交换树脂D730、D202和SD333对异嗅物质的总体去除效果最好。     

Effect of Grain Size of AgNO3 Loaded in Porous Material on Adsorption of CH3I

In the development of a new chemical decontamination method which provides a high decontamination effect, less corrosion of base metal, and less radioactive waste generation, we developed a decomposition method for oxalic acid coexisting with hydrazine to decrease the amount of radioactive waste.

Using a catalyst of 0.5 wt% Ru supported by activated carbon grains, we decomposed oxalic acid and hydrazine, simultaneously and efficiently, with a stoichiometric concentration of H₂O₂2. The decomposition ratios were decreased by the deposition of oxides. But even if the simulated reducing agent solution with high concentrations of coexisting Fe and K ions, which negatively effect decomposition ratio, was decomposed, the decomposition ratios of oxalic acid and hydrazine were kept high during decomposition of the amount of reducing agent used in actual chemical decontamination.

Additionally, we examined the deposition ratios of metal ions on the catalyst as metal oxides. These results indicated about 2% of the radioactive species which were removed by the chemical decontamination were deposited on the catalyst column. ⁵⁹Fe and ⁵¹Cr were estimated to be about 90% of the total deposited amount of radioactive species and about 60% of the dose equivalent in the model calculation. But this problem should be easily dealt with by using shielding.     

Removal of Tritiated Water Vapor by Adsorption

Abstract

Experiments were conducted on the dynamic adsorption of tritiated water vapor, using a column packed with either silica-gel, activated alumina, or molecular sieve 5A. The column was 4 mm I.D. and 5–30 cm long. The runs were performed at 30°–70°C. Tritiated water vapor (HTO) was loaded into the column with a concentration of 170 μμCi/ml, either in pulses of predetermined duration or continuously (breakthrough). The concentrations of H₂O and HTO at column outlet were measured. Particular interest was attached to observing the effect of differences in the pretreatment applied to the adsorbents (whether dried or saturated with water), and in the H₂O partial pressure of the carrier gas. It was found that the adsorption characteristics shown for HTO were not influenced to any appreciable extent by differences in the pretreatment applied to the adsorbents. On the other hand, adsorbent performance depended sensitively on the H₂O pressure in the carrier gas.

Adsorption models for a two-component mixture composed of H₂O and HTO were sought for describing the adsorption mechanism. For the particular case of the molecular sieve 5A, the Langmuir-type mixed adsorption model was found to give values agreeing fairly well with experiment. A model postulating chemisorption of H₂O into hydroxyl group on the adsorbent surface, to be subsequently replaced by tritium, was found suitable for explaining the adsorbent behavior in the case of silica-gel.     

Uranium Extraction from Sea Water with Composite Adsorbents, (II)

A composite hydrous oxide, prepared from the mixed solution of titanium tetrachloride and ferrous chloride by addition of sodium hydroxide solultion, was investigated because of its rather high uranium adsorption capacity and its magnetic property. Results obtained may lead to easier handling of adsorbent species in the extraction of uranium from sea water.

The uranium adsorption capacity of the composite hydrous oxide was measured using sea water to which a small amount of uranyl chloride was added. The initial uranium concentration was 10.1 μg/l. Physical and chemical properties, such as specific surface area, mean pore radius and amount of surface OH groups, were also measured. The composite hydrous oxide was found to be composed mainly of relatively small particles of anatase and large particles of magnetite. Uranium adsorption capacity reaches its maximum when the precipitation temperatures are 50–70°C. The capacity of the composite hydrous oxide was found to be closely related to the mean pore size and the amount of surface OH groups.     

Attrition of Ca‐based CO2‐adsorbents by a high velocity gas jet

Attrition of Ca‐based adsorbents is a subject of interest that determines the efficiency of the Ca‐looping process for CO₂ capture. In this article, we report an experimental test to assess the mechanical strength of cohesive Ca‐based adsorbents based on particle sizing by laser diffractometry. In this technique, the powder sample is dispersed, either by a high velocity air jet (dry dispersion) or by a liquid before the particle size distribution (PSD) is measured. In the dry dispersion unit, particle aggregates are subjected to high energy collisions intended to cause their fragmentation. The PSDs obtained at a low dispersive air pressure for calcined CaO shows that there is a remarkable population of large aggregates due to strong van der Waals of attraction. A second population consists of compact small aggregates, which are relatively stronger due to material sintering at interparticle contacts. As the dispersive air pressure is increased, these aggregates are broken. Their size scales as a power law of the jet air velocity in agreement with the prediction of a fracture mechanics theory of brittle materials. In contrast, the population of large aggregates of a modified adsorbent, consisting of a CaO/nano‐silica composite, is not significative, which can be attributed to the effect of nano‐silica in decreasing the van der Waals attractive force. Moreover, the small compact aggregates of the composite are broken at a lower rate with the dispersive air pressure. The enhanced strength of these composite aggregates is further supported by the PSDs obtained for samples dispersed in a liquid and previously excited by high energy ultrasonication. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1096–1107, 2013     

负载型K2CO3/Al2O3吸收剂吸收CO2反应机理

利用热重分析仪、扫描电镜和氮吸附仪对不同粒径的K₂CO₃颗粒和负载型K₂CO₃/Al₂O₃二氧化碳吸收剂的碳酸化特性进行研究。负载后的吸收剂比表面积和孔隙结构得到较大改善,使得碳酸化反应速率和转化率均提高,吸收剂碳酸化特性得到改善。纯K₂CO₃颗粒吸收剂的反应速率和转化率随着粒径的增加而减小,负载型吸收剂的反应速率和转化率随着粒径的增加略增大。研究了不同粒径和反应时间对K₂CO₃/Al₂O₃颗粒微观结构的影响,结果表明K₂CO₃/Al₂O₃颗粒具有较稳定的微观结构。采用负载型粒子模型对K₂CO₃/Al₂O₃吸收剂吸收CO₂碳酸化过程进行研究,所建立的粒子模型计算结果与试验值吻合较好。利用建立的模型对不同CO₂浓度下K₂CO₃/Al₂O₃吸收剂碳酸化反应特性进行模拟计算,模拟结果具备一定的合理性和准确性,为开展进一步研究提供了基础。     

月桂酸改性生物质材料处理乳化油的机理

油污染对环境、生物和经济产生了不利的影响。目前,诸多研究均希望得到一种有效、简单且价廉的除油方法。为了提高对含乳化油废水的处理效果,以玉米芯和花生壳为原料,采用月桂酸对其进行改性,并且利用扫描电镜、比表面积测试和红外光谱等测试手段研究生物质材料的改性和处理含乳化油废水的机理。研究发现,月桂酸改性是利用月桂酸上含有的羧基和生物质材料的纤维素、半纤维素和木质素上含有的羟基发生的酯化反应,形成的酯基链接月桂酸本身的烷基链,增强了亲油疏水性,同时也有造孔的作用即进一步增大微孔和提高孔隙率,由于改性材料是通过亲油性烷基链和微孔吸附油粒子,因此这两者的共同作用提高了材料的吸油能力。利用石油醚萃取水中油分,采用紫外分光光度法测定水中的油浓度。这种方法能够更加直接地看出含乳化油废水的处理程度,也更加贴近实际工程概况。研究表明,原始玉米芯和花生壳对含乳化油废水的油吸附容量分别是6.86 mg·g^-1和5.21 mg·g^-1,经月桂酸改性后,其吸附容量有了较大提高,分别达到了10.79 mg·g^-1和7.44 mg·g^-1。因此,当处理含乳化油废水时,利用月桂酸改性玉米芯和花生壳不仅能高效率除油,而且基于以废治废,是一项相当环保的措施