Dynamic properties on 99Mo adsorption and 99mTc elution with alumina columns

The Mo adsorption/99mTc elution properties of alumina used as Mo adsorbents are examined for the development of 99Mo/99mTc generators using 99Mo produced by the (n, γ) method. MoO3 is irradiated by the Kyoto University Research Reactor (KUR). The alumina columns are filled with three types of alumina made from different raw materials. In this paper, elongated tubes are used as columns and the properties under Mo dynamic adsorption conditions on alumina are compared with those under static adsorption conditions. The results obtained suggest that the 99Mo/99mTc ratio specified by the Minimum Requirements for Radiopharmaceuticals of Japan (MRRP) is greatly affected by the method of adsorbing Mo on alumina.

Adsorption of anionic surfactant on surface of reservoir minerals in alkaline-surfactant-polymer system

Alkaline-surfactant-polymer (ASP) flooding is significant to the oil and gas industry due to synergistic interaction between alkaline, surfactant and polymer. However, chemical losses due to adsorptions of surfactant and polymer on the rock surface could lead to inefficiency of the process. There are also significant uncertainties on adsorption mechanism when surfactant is flooded with presence of alkaline and polymer. This study highlights the static adsorption tests using anionic sodium dodecyl sulphate (SDS), hydrolysed polyacrylamide (HPAM) and sodium carbonate (Na2CO3) as the surfactant, polymer and alkaline, respectively. Sand particles and kaolinite clay were used as the reservoir minerals. The adsorption tests were conducted at various surfactant concentrations ranging from 50 to 2000 ppm. Sodium chloride (NaCl) concentration was investigated from 0 to 2 wt.%, while the local sand and kaolinite was mixed in surfactant solution at a fixed mass to volume ratio of 1:5. The static adsorption test was conducted by shaking the mixture samples and centrifugation before analysing the supernatant liquid using UV-Visible spectrophotometer. The results showed that the surfactant adsorption was higher on kaolinite compared to sand particle. The higher the salinity, the higher the adsorption of surfactant due to higher ionic strength. The adsorption of SDS surfactant on sand particles and kaolinite was lesser in ASP system compared to the presence of surfactant solution alone. Thus, it can be concluded that the presence of polymer and alkaline in ASP solution have great potential to reduce the surfactant adsorption on both sand particle and kaolinite.

Design of Laboratory Studies to Develop the Chemical Formulation for Surfactant-Polymer Flooding

Nowadays, chemical EOR methods are becoming more and more relevant, among which the alkali-surfactant-polymer flooding is of particular interest. The efficiency of this technology largely depends on the correct choice of the components of chemical formulation, which should be based on a set of laboratory experiments carried out in a given sequence. This paper presents a methodological approach to laboratory studies in order to develop an optimal surfactant-polymer formulation, taking into account the geological and physical characteristics of the target field and the properties of reservoir fluids. The experimental part of the research work was carried out in several stages, involving the analysis of the physicochemical characteristics of reservoir oil, the screening studies of surfactant and polymer samples, as well as a series of coreflood tests with a selected chemical formulation on the terrigenous reservoir models. During screening studies, the solubility and compatibility of the chemical components, the phase behavior of surfactant solutions with oil at different salinity values and water-oil ratios, static adsorption of chemicals on the rock and their thermal stability at reservoir temperature were investigated. Optimization of the chemical formulation was based on the results of IFT measurements of the surfactant solutions and rheological studies of the polymer solutions. At the stage of coreflood tests, physical simulation of the surfactant-polymer flooding was carried out on reservoir models using natural core material in order to optimize the composition and slug size of the developed chemical formulation. The obtained results of the displacement experiment were matched by numerical 1D simulation. Based on the results of the studies performed, an effective surfactant-polymer formulation has been designed, which provides the ultra-low IFT (2.8·10−4 mN/m) values and the ability to form stable middle-phase microemulsions when interacting with oil. The findings of thermal stability and static adsorption experiments confirmed a feasibility of selected chemicals for practical application. Within the framework of the study, the key technical parameters of proposed formulation were determined, which are required for up-scaled simulation study of the chemical flooding process at pilot site.

Crown Ether Grafted Graphene Oxide/Chitosan/Polyvinyl Alcohol Nanofiber Membrane for Highly Selective Adsorption and Separation of Lithium Ion

Nanofiber membranes were successfully prepared with crown ether (CE) functionalized graphene oxide (GO), chitosan (CS), and polyvinyl alcohol (PVA) by low-temperature thermally induced liquid–liquid phase separation. The physical and chemical properties and adsorption performance of nanofiber membrane were studied through SEM, FT-IR, XRD, and static adsorption experiments. The results show that the specific surface area of the nanofiber membrane is as high as 101.5 m2∙g−1. The results of static adsorption experiments show that the maximum adsorption capacity of the nanofiber membrane can reach 168.50 mg∙g−1 when the pH is 7.0. In the selective adsorption experiment, the nanofiber membrane showed high selectivity for Li+ in salt lake brine. After five cycles, the material still retains 88.31% of the adsorption capacity. Therefore, it is proved that the material has good regeneration ability.