Polymeric Titanium Oxychloride Sorbent for 188W/188Re Nuclide Pair Separation

Abstract

The chemical synthesis conditions (TiCl₄: iPrOH reagent ratio and reaction temperature scheme) were optimized for the preparation of polymeric titanium oxychloride sorbent which met the requirements for clinically useful ¹⁸⁸W/¹⁸⁸Re generator production, such as high W-adsorption capacity, high ¹⁸⁸Re-elution yield, low ¹⁸⁸W-breakthrough, and good mechanical stability. This polymeric material was formed by polycondensation of titanium-oxychloride units, the chemical formula of which was supposed as [OTiO (Ti₄₀ Cl₈₀ (OH) ₈₀ (TiO₂)₉₅.60H₂O) OTiO]_n. The effect of the W-content of tungstate solution on the WO₄ ^2? ion adsorption (with minimizing the poly-tungstate ion adsorption) and its covalent bonding with the Ti metal atoms in the polymeric matrix were justified with respect to the optimal W-adsorption conditions for the preparation of a useful ¹⁸⁸W/¹⁸⁸Re generator column. The high W-adsorption capacity of about 515.6 mg W/g sorbent and ¹⁸⁸Re elution yield of higher than 85% wereachieved. The large difference in the distribution ratio values found for alumina and polymeric titanium oxychloride sorbent in 0.005% NaCl solution (D_{W, Re-188} = 50 and D_{W, Re-188} = 1.0, respectively) offered an advantage for the preparation of a consecutive-elution based ¹⁸⁸Re generator system which combined both ¹⁸⁸Re elution and ¹⁸⁸Re concentrating processes in one portable system. This generator system is of a tandem column type which consists of a polymeric titanium oxychloride sorbent coupled to an alumina column. This system gave a ¹⁸⁸Re concentration factor of approximately 10. The overall ¹⁸⁸Re yield achieved from this system was >80%. ¹⁸⁸W isotope and elemental tungsten breakthrough were not detected in its ¹⁸⁸Re eluate. This system thus offers a potential application for clinically useful ¹⁸⁸Re production using low specific radioactivity ¹⁸⁸W (around 500 mCi/g) producible in a medium neutron flux reactor.     

The efficient lignocellulose-based sorbent for oil spill treatment from polyurethane and agricultural residue of Vietnam

In this study, new and efficient sorbent with density 0.2 g/cm³ was fabricated by incorporating rice straw into polyurethane matrix to get an open cell structure material with high oil uptake capacity. The influences of various important factors such as amount of adding rice straw, size of rice straw particles, and adsorption time on oil adsorption capacity of new sorbent material were investigated. The results showed that the oil absorption rate occurred fast in first 15–30 min, then slowed down and reached saturation level after about 2 h of treatment. Oil adsorption capacity of the new sorbent material was relatively high, up to 12.0 g/g. In comparison with pristine polyurethane or lignocellulosic materials, the new sorbents had higher oil adsorption capacity. Some characteristics of the as-obtained sorbent, such as surface shapes and porosity, were also studied by SEM analysis.     

氧化铈高温煤气脱硫剂制备条件对脱硫效率的影响

采用工业硝酸铈Ce(NO₃)₃6H₂O为原料进行热解制取脱硫活性组分CeO₂,然后利用干混法制备CeO2高温煤气脱硫剂。通过BET、XRD、强度仪等测试手段,对脱硫剂的孔容、比表面积、晶型以及机械强度等进行了表征;同时在固定床反应器中考察不同焙烧温度、不同造孔剂含量以及不同黏结剂对脱硫剂脱硫效率的影响。结果表明:在500～800 ℃的范围内,随着焙烧温度的增加,比表面积迅速增大,孔容也大幅度上升,机械强度也呈现增加的趋势,并且脱硫效率也随着焙烧温度的升高而升高;且造孔剂含量的增高,脱硫效率也有增高的趋势,但机械强度有所降低。选用膨润土作为黏结剂更有利于氧化铈脱硫剂的脱硫过程。故合适的焙烧温度、适量造孔剂的加入及选用合适的黏土都可以改善氧化铈脱硫剂的脱硫活性。     

S Zorb吸附剂中硅酸锌生成速率分析

选用S Zorb工业吸附剂FCAS-R09,考察了不同条件对吸附剂中硅酸锌生成速率的影响.结果表明:在无水情况下,吸附剂中硅酸锌的生成温度高达800℃;水蒸气的存在能够明显促进硅酸锌的生成,在水蒸气分压为10 kPa的情况下,在温度低于500℃下就有硅酸锌生成,并且吸附剂中硅酸锌的生成速率随系统内水蒸气分压或温度的升高...     

Characterization of calcium oxide derived from waste eggshell and its application as CO2 sorbent

The carbonation-calcination looping cycle of calcium-based sorbents is considered as an attractive method for CO₂ capture from combustion gases because it can reduce the cost during the capture steps compared to conventional technologies, e.g., solvent scrubbing. In this study, waste eggshell was used as raw material for calcium oxide-based sorbent production. The commercially available calcium carbonate was employed for comparison purpose. Calcination behavior, crystal type and crystallinity, surface chemistry, qualitative and quantitative elemental information, specific surface area and pore size, morphology of the waste eggshell and the calcined waste eggshell were characterized by thermal gravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray fluorescence (XRF), N₂ sorption analysis and scanning electron microscopy (SEM), respectively. The carbonation-calcination cycles were carried out using a TGA unit with high purity CO₂ (99.999%). It was found that the carbonation conversion of the calcined eggshell was higher than that of the calcined commercially available calcium carbonate after several cycles at the same reaction conditions. This could be due to the fact that the calcined eggshell exhibited smaller particle size and appeared more macropore volume than the calcined commercially available calcium carbonate. As results, the calcined eggshell provided a higher exposed surface for the surface reaction of CO₂.     

Study on the heat transfer and sorption characteristics of a consolidated composite sorbent for solar-powered thermochemical cooling systems

In this paper, a new consolidated composite sorbent made from barium chloride and expanded graphite is presented for solar-powered thermochemical sorption cooling systems. A larger sorption capacity and volume cooling density can be obtained with chemisorption systems when compared with those based on physicosorption. The heat transfer and sorption characteristics of the composite sorbent were investigated. Experimental results showed that the chemical composite sorbent can effectively utilize solar energy or low-grade waste heat sources with temperature ranging from 75 to 90 °C, and it could incorporate 0.61 kg of ammonia per kg of the reactive salt. The temperature evolution in the reactor was strongly influenced by the physicochemical reaction, whereas the transient heat transfer properties in the reactive composite material were different during the decomposition and the synthesis phases owing to the variation of the ammonia content and solid configuration inside the metallic salt complex. The rate of conversion in the reactor was very sensitive to the working temperatures and pressures, and the COP (coefficient of performance) obtained with the consolidated composite sorbent varied between 0.50 and 0.53 when the evaporation temperature ranged from 0 to 15 °C at a generation temperature of 80 °C.     

Removal of sulfur compounds from utility pipelined synthetic natural gas using modified activated carbons

Synthetic natural gas (SNG), which is produced from petroleum and distributed via pipeline in Honolulu by The Gas Company, was analyzed using a gas chromatograph equipped with a sulfur chemiluminescence detector (GC/SCD). Hydrogen sulfide (H₂S), methyl mercaptan (MM), ethyl mercaptan (EM), dimethylsulfide (DMS), dimethyl disulfide (DMDS), tetrahydrothiophene (THT), ethyl disulfide (EDS), and one unidentified compound (UN1) were detected. Among these sulfur compounds, THT is added as an odorant and was present in the highest concentration.A commercial activated carbon (Calgon OLC plus 12X30) was modified by oxidation and impregnation methods and the resulting materials were evaluated for their ability to adsorb sulfur compounds present in SNG. The evaluation results indicate that all of the modification methods can improve the retention of individual sulfur compounds or the total sulfur capacity compared with the untreated virgin carbon. It is also found that activated carbons impregnated with metal impurities have different selectivity for sulfur compounds. Cu and Zn loaded carbons had the highest capacity for H₂S removal, Fe loaded carbon was more efficient for DMS removal (the most difficult S compound to remove), and carbon oxidized by HNO₃ was the best for THT removal.Based on these findings, a composite sorbent consisting of Cu loaded and Fe loaded carbons was designed and tested. The test results indicate that the composite sorbent had improved performance in the removal of individual sulfur compound. A linear programming model was used to design a composite sorbent optimized to minimize the required sorbent mass based on a 1-kW scale fuel cell system service target. Validation tests showed that the optimized sorbent required less of the individual modified carbon components than when they were individually used for the same sulfur removal target.     

Solid‐phase extraction of phenolic compounds with poly[metalloprotoporphyrin IX]

A highly insoluble metalloporphyrin polymeric material was used as sorbent for the solid‐phase extraction of phenolic compounds. Substantial quantities of phenols (40 to 60 mg/g polymer) were absorbed from aqueous solution comparing satisfactorily with other extraction methods. The polymeric phase presented similar K_SPE values for the hydrophobic compounds tested such as p‐chlorophenol, BPA, p‐nitrophenol, and a significant lower value for the more hydrophilic p‐aminophenol and cresol. Several metallic complexes of protoporphyrin IX (Co²⁺, Cu²⁺, Ni²⁺, Zn²⁺, and Fe³⁺) have been tested. The analytes were extracted with high recoveries at acid and neutral pH values, whereas at pH 10 low recoveries were obtained. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3038–3043, 2001     

Regenerable MgO-based sorbents for high-temperature CO2 removal from syngas: 1. Sorbent development, evaluation, and reaction modeling

Highly reactive and mechanically strong low-cost regenerable MgO-based sorbents were prepared by modification of dolomite which involved partial calcinations followed by impregnation with a potassium-based salt. The sorbents are capable of removing CO₂ from gasification-based processes such as Integrated Gasification Combined Cycle (IGCC). The sorbents have high reactivity and good capacity toward CO₂ absorption in the temperature range of 300-450 °C at 20 atm. and can be easily regenerated at 500 °C. The reaction appears to be first order with respect to CO₂ concentration with an activation energy of 44 kJ/mol. The reactivity and the absorption capacity of the sorbents increase with increasing temperature, as long as the partial pressure of CO₂ is above the equilibrium value for sorbent carbonation. The reactivity of the sorbents appears to improve in the presence of steam, which is likely due to the increase in the BET surface area and the porosity of the sorbent. A two-zone expanding grain model, consisting of a high-reactivity outer shell and a low-reactivity inner core is shown to provide an excellent fit to the TGA experimental data on sorbent carbonation at various operating conditions.     

钙基脱硫剂高温分解特性模拟研究

以反应动力学为基础，考虑CO2在产物层中的扩散影响、分解过程中CaO的高温烧结作用及CO2的烧结影响。模拟研究钙基脱硫剂石灰石(CaCO2)在不同的反应温度、气氛及颗粒粒径下的分解特性及生成CaO的比表面积变化情况。