高温煤气铁钙基脱硫剂再生研究

在固定床装置上考察了温度和氧浓度对铁钙基脱硫剂再生率以及二次脱硫活性的影响，同时还考察了此脱硫剂用于模拟的脱硫除尘一体化条件下，黏附于表面的粉尘对脱硫剂再生行为以及二次脱硫行为的影响。结果表明，该脱硫剂在480 ℃下再生效果良好，650℃再生率下降，在考察的温度区间内（400 ℃～650 ℃）温度对二次脱硫活性影响较小，在以后的循环中，温度对再生率以及脱硫活性的影响也小，再生气氛中氧浓度对再生率以及二次脱硫活性的影响不明显；研究发现加入粉尘虽然会降低脱硫剂的再生率，但基本不影响二次脱硫活性。     

Demulsification of water-in-oil emulsions via filtration through a hydrophilic polymer membrane

It is known that hydrophobic microfiltration membranes can be used for demulsification of oil-in-water (o/w) emulsion due to coalescence of oil droplets in membrane pores. This study demonstrates that a hydrophilic polymer membrane can be used for the demulsification of surfactant-stabilized water-in-oil (w/o) emulsions. The success of demulsification is dependent on the type of emulsions and membrane used. Membrane pore size and transmembrane pressure were found to affect demulsification efficiency (DM), while other factors, such as membrane thickness and initial water content have slight or almost no effect. A coalescence mechanism of the demulsification phenomenon is also discussed. The separation process is not based on sieving effects due to a difference in membrane pore size, but is determined by droplet interactions with membrane surface.     

Aluminum-type superparamagnetic adsorbents: Synthesis and application on fluoride removal

Two effective types of superparamagnetic nano-scale adsorbents of bayerite/SiO₂/Fe₃O₄ have been synthesized via three sequential steps: chemical precipitation of Fe₃O₄, coating of SiO₂ on Fe₃O₄ using acidifying method, and further coating of bayerite (Al(OH)₃) on SiO₂/Fe₃O₄ adopting sol–gel (MASG) or homogeneous precipitation (MAHP) methods. The characteristics of MASG and MAHP were identified using the transmission electron microscopy (TEM) micrograph, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX), X-ray powder diffractometer (XRD), and superconducing quantum interference device (SQUID). Removal of fluoride from aqueous solution was examined to evaluate the adsorptive capacity of MASG, MAHP, and commercial activated alumina (CA), and the effects of enclosure of Fe₃O₄ with SiO₂ for SiO₂/Fe₃O₄, MASG, and MAHP particles. Among the adsorbents tested under the same experimental condition, MASG is the most effective adsorbent, of which the adsorption capacities are 38 g/kg (based on adsorbent mass of adsorption in terms of equilibrium constant q_L of Langmuir isotherm), and can compete with CA even at a high pH value. The innovative superparamagnetic adsorbents synthesized in this study possess physicochemical stability at pH range of 6–8 and great potential in the adsorption processes due to not only their high adsorption capacity but also the conveniently magnetic separation which can overcome the difficulty in solid–liquid separation for nano-particles in solutions.     

Critical Eotvos numbers for buoyancy-induced oil drop detachment based on shape analysis

Critical values of the Eotvos number, which is half the Bond number, above which buoyancy induced drop detachment occurs, are estimated based on force balance equations available in the literature [Colloids Surf. A: Physicochem. Eng. Aspects 178 (2001) 249]. Since there are two significantly different expressions of the capillary retention force responsible for holding oil drops on a solid substrate in an aqueous phase, the critical dimensionless number is estimated with these two distinct equations. The differential equation defining the drop shape, with the constraints of the drop volume and the 'pinned' or 'receding' contact line, is numerically solved. The equilibrium drop shapes predicted are shown to match the experimentally observed variations in drop shape. From the numerical solution, it is observed that for interfacial tension (IFT) values lower than a certain limit for a given drop size, no numerically estimated drop shape can fulfil the drop volume constraint. Similarly, for the dimensionless number above a critical value, no shape can meet all the constraints. These critical Eotvos numbers are estimated, based on the above numerical approach, for initial contact angles measured in oil varying from 20 degrees to 90 degrees. It is found that the critical Eotvos numbers estimated from the numerical shape analysis are between the critical values estimated from the two force-balance equations. Near 90 degrees, the critical values estimated from the drop shape analysis matches the values from one of the force balance estimates, but merges with the critical values of the dimensionless number, estimated from the other force balance model near 10 degrees. From this analysis, it appears that a combination of the two equations for the capillary retention force is required, with one dominating when the contact angles are high, while the other applies for low values of the contact angle.     

UiO-66/CoSO4复合材料对环境中盐酸左氧氟沙星的高效去除

以UiO-66为前驱体制得UiO-66/CoSO₄复合材料，借助扫描电子显微镜、透射电子显微镜、元素分析和比表面积分析等手段对复合材料的微观形貌和结构进行表征，采用吸附平衡实验，系统考察该复合材料的吸附性能.结果表明，在相同条件下UiO-66/CoSO₄复合材料比UiO-66对盐酸左氧氟沙星的去除率提高26.5%，且复合材料在30 min对盐酸左氧氟沙星的吸附达到平衡，最大吸附容量为108.4 mg·g^-1，其吸附特性符合假二级动力学模型.该UiO-66/CoSO₄复合材料制备过程简单，对实际环境水样和土样中盐酸左氧氟沙星的去除率在94.7%以上，且经过5次再生循环使用后，吸附效率无明显下降.     

Molecular assessment of S1 endonuclease-resistant snapback hairpin loops generated by DNA polymerase I during the in-vitro nick translation reaction

The in-vitro nick translation reaction used to label DNA to high specific activity also produces aberrant DNA structures known as “snapback” hairpin loops. Hairpin structures are precluded from participating in precise DNA-DNA hybridization interactions. Three nick translation systems were all found to yield significant quantities of snapback hairpins, as determined by their resistance to S1 endonuclease digestion following denaturation. The relative quantities of hairpins produced correlated with both the mass average size of the final DNA probe product synthesized as well as the overall rate of the nick translation reaction. Decreases in the amount of exogenous DNase I used in nick translation reactions produced significant decreases in the amount of hairpin loop structures formed. Hairpins could be effectively removed from nick-translated DNAs by employing hydroxylapatite column chromatography. Strategies to reduce hairpin formation during nick translation and the removal of hairpins from nick-translated DNAs are presented.     

Removal of Cd（ Ⅱ ） from Aqueous Solutions by Natural Freshwater Surface Coatings

Natural freshwater surface coatings (biofilms and associated minerals), which were developed in the Nanhu Lake, Changchun, P. R. China, were used as an efficient biosorbent for the removal of Cd(Ⅱ) from aqueous solutions. The batch experiments were carried out to determine the adsorption properties of Cd(Ⅱ) onto the natural surface coatings. The classical Langmuir adsorption isotherm was applied to estimating the equilibrium coefficients of Cd(Ⅱ) adsorbed on the surface coatings. The results show that the maximum adsorption capacity of the surface coatings is 434. 78μmol Cd/m^2 (being equal to 0. 17mmol Cd/g of surface coatings or 10. 38mmol Cd/g Fe) and the Cd(Ⅱ) remnoval from solution media by the natural surface coatings was shown to be strongly affected by solution pH and ion strength. The resulted information also indicates that the maximum Cd removal efficiency(CRE) was determined to be approximately 90% at initial Cd mass concentration of 0. 1mg/L (the concentration limit of Cd (Ⅱ) in wastewaters for discharge in aquatic media in Chinese legislation), and the kinetic adsorption of Cd (Ⅱ) onto the surface coatings is fast with around 70% of the total adsorption-taking place in 150min in solution under the controlied laboratory conditions (mineral salts solution with defined speciation, ionic strength 0. 05mol/L, and 25℃). With the advantage of high Cd adsorption capacity, the natural surface coatings appear to be a potentially effective biosorbent for the removal and recovery of Cd(Ⅱ) from polluted water.     

Study by thermal methods on the materials obtained by dye removal from waste waters with beech flour

The study is devoted to the characterization by both TG-DTG analysis and FTIR spectroscopy of beech flour, dyes and the sorbent-dyes products obtained through retention of the dyes from aqueous solution on the beech flour, to the aim of obtaining information on the nature of dyes’ retention, thermal behavior of the sorbent-dye materials as well as on their possible upgrading as fuel. Thermal analysis led to the conclusion that the mechanism of thermo-oxidative degradation is specific and the retention of dyes occurs on cellulose from beech flour. The nature of the bonds involved in dyes’ retention is also investigated by FTIR analysis, which evidences that dyes retention on cellulose is realized through hydrogen bonding between the NH and, respectively, OH groups from dye molecule and the oxygen atoms from cellulose. Involvement of the non-participating electrons of the nitrogen and, respectively, oxygen atoms of these groups in the extended electronic conjugation with aromatic nuclei strongly influences the capacity of the amino and, respectively, hydroxyl groups of forming hydrogen bonds, thus achieving dyes fixation on the sorbent. DTA analysis led to the conclusion that an improvement in the quality of the sorbent-dye materials as fuels is possible, as compared to untreated beach flour, as a result of the modification of the cellulosic fibers in the process of dyes retention.     

Kinetics of SO2 removal from flue gas by electron beam technique

Laboratory scale experiments were carried out in order to get more information about the oxidation of SO₂ by OH radicals (homogeneous reaction) and the oxidation of SO₂ at aerosol surfaces (heterogeneous reaction). For the experiment of homogeneous reaction, SO₂ was added to synthetic flue gas without initial NO and without ammonia and the mixture was irradiated with electron beam. The SO₂ removal was measured as a function of temperature and water vapour concentration at constant dose. For the experiment of heterogeneous reaction, SO₂ was added to nucleating sulfuric acid aerosol. No SO₂ removal was observed in this case. So, it can be concluded that the heterogeneous oxidation of SO₂ is negligible in the absence of ammonia. Therefore, the oxidation of SO₂ must be interpreted merely by homogeneous gas phase chemistry. The gas phase kinetics are derived from comparison of experimental results and computer modelling.     

Removal of heat of adsorption from adsorbent by forced convection

An analytical mathematical model is used to investigate the effectiveness of forced convection for removal of the heat of adsorption from an adsorbent mass undergoing a differential adsorption process in a flow system. An example of such a process is measurement of gas adsorption kinetics using a differential adsorption bed. Isothermal operation may not be achieved even when a high gas flow rate is used, particularly if the sorption kinetics is relatively fast. Very small changes in the adsorbent temperature can cause significant departure from the isothermal uptake behavior when the heat of adsorption is moderately large. A criterion for validity of isothermal data analysis is given.