Improving the cold flow properties of biodiesel from waste cooking oil by ternary blending with bio-based alcohols and diesel from direct coal liquefaction

The utilization and popularization of biodiesel are always limited by its poor cold flow properties. Both bio-based alcohol and diesel from direct coal liquefaction (DDCL) has potential to enhance the cold flow properties of biodiesel. In this study, ternary blends of waste cooking oil biodiesel (BWCO) with DDCL and bio-based ethanol (ET) or 1-butanol (BT) were conducted to improve the cold flow properties of biodiesel. The pour point (PP), cold filter plugging point (CFPP), and cloud point (CP) of BWCO-ET, BWCO-BT, and BWCO-DDCL binary blends, and BWCO-ET-DDCL and BWCO-BT-DDCL ternary blends were comparatively assessed. Ternary phase diagrams were also applied to analyze the blending effect of the three components on the cold flow properties of biodiesel. Results showed that both DDCL, ET, and BT can remarkably enhance the cold flow properties of BWCO. When the ternary blends contain 20 vol.% BWCO and less than 40 vol.% ET or BT, DDCL together with ET or BT exerted positive effects on enhancing the low-temperature flow properties of BWCO, especially on the CP and CFPP. For ternary blends in 20:10:70 blending ratio, BWCO-BT-DDCL exhibited the lowest PP, CFPP, and CP of −23, −19, and −17°C, respectively. The crystallization behavior and crystal morphology of blended fuels are also observed via a polarizing optical microscope, and find that DDCL together with BT in biodiesel can effectively retard the aggregation of large crystals and inhibit crystals growth.     

Dealuminated Y Zeolite for Water-Driven Adsorption Heat Pumps: Hydrothermal Stability

Silica gel or zeolites AlPO-5 and SAPO-34 are recommended as adsorbents in water-driven heat pumps because of their selective water uptake. Secondary energy, like solar energy, can be used for regeneration of loaded adsorbers. In case of the availability of only low energy levels, the use of dealuminated Y zeolite (DAY) is the better choice because of the infinitely variation of its hydrophilic properties by tailoring of the framework Si/Al ratio. Actual data on the hydrothermal stability of DAY are lacking. Thus, we report on the long-term behavior of DAY zeolites with different Si/Al ratios.     

乙二醇水热还原法制备纳米银

利用乙二醇在高温下的还原特性,在水热条件下制备了纳米银粒子,并通过透射电镜、X射线衍射、紫外吸收光谱对其结构进行了表征.研究结果表明:所制备的纳米银具有面心立方相的多晶结构,平均粒径在30nm左右,紫外吸收峰的位置在380 nm左右.分散剂和体系中含水量对纳米银的粒径有一定影响.     

黄土滑坡地震液化数值模拟分析——以宁夏石碑塬滑坡为例

以宁夏石碑塬滑坡为研究对象,在工程地质测绘和试验测试的基础上建立了有限差分数值模型,对该黄土坡液化过程进行了模拟。分析结果表明：该黄土边坡在天然工况下处于稳定状态;在地震作用下,非饱和黄土几乎没有液化现象,而在地下水位附近的饱和黄土易发生液化,导致其物理力学参数降低,即使在很缓的角度下也易产生边坡失稳;地震结束之后,由于液化导致孔压比减小,黄土渗透性较之前更低,边坡的孔隙水压力消散缓慢,滑带强度恢复也缓慢,易产生长距离滑动。      

水下粉细砂土体在超高频机械振动荷载作用下液化特性的试验研究

为了量化高频机械振动对土壤液化的具体效果,在试验室泥槽中对不同性质的水下粉细砂沉积物开展了诸如不同振动作用时间及不同工况下的液化试验,利用静力触探仪测量了振动作用前后其承载力变化情况,基于试验数据分析讨论了振动作用时间、振动作用距离、振动频率对于液化效果的影响.     

Hydrothermal synthesis of hollow ZnSnO3 microspheres and sensing properties toward butane

Hollow ZnSnO₃ microspheres were successfully prepared by hydrothermal method at 160 °C for 12 h. The prepared material was characterized by field emission scanning electron microscope (FESEM), transmission electron microscope (TEM) and X-ray diffraction measurements (XRD). The average diameter of the hollow ZnSnO₃ microspheres was in the range of 400-600 nm. Compared with solid ZnSnO₃ microspheres structure, the hollow ZnSnO₃ microspheres showed better response (S) to butane. To 500 ppm butane, the sensor response (S) of the hollow ZnSnO₃ microspheres was 5.79 at the optimum operating temperature of 380 °C, and the response and recovery time were 0.3 s and 0.65 s, respectively. The sensitivities of sensors based on this material were linear with the concentration of butane in the range of 100-1000 ppm.     

Investigation of Raman enhancement in hydrothermally roughened SERS-active substrates

In this work, we study surface enhanced Raman spectroscopy (SERS) active substrates for the detection of Rhodamine 6G. To examine the electromagnetic enhancement, we apply the finite-difference time-domain (FDTD) algorithm to analyze the structures by solving a set of coupled Maxwell's equations (Ampere's Law and Faraday's Law) in differential form. The field enhancements are thus investigated in the visible regime with the wavelength of 633 nm. In our experimental measurement, the surface enhanced Raman scattering signals from the surface of substrates with 12-hour treatment and without treatment are performed and compared. Through the three-dimensional (3D) FDTD calculation, we find that the hydrothermally 12-hour treated samples possess significantly vertical variations of surface and thus have relatively larger field enhancement than those without treated. Consequently, it implies a strong positive effect on the surface enhancement which is consistent with the measured intensity.     

Preparation of bao-pbo-nd2o3-tio2 powders by hydrothermal synthesis

Homogeneous and nano-sized BPNT [(Ba_1-xPb_x)Nd₂Ti₅O₁₄] powders were prepared under various hydrothermal conditions. Crystallinity and homogeneity of the synthetic powders were investigated. The microwave dielectric properties of the filters prepared with hydrothermal powders were compared with those of the filters prepared with conventional powders. The microwave dielectric properties of the filter prepared with the hydrothermal powders were also better than those of the filter manufactured with the conventional powders. The dielectric constant, quality constant and temperature coefficient of resonance frequency of hydrothermally prepared filter under optimum condition and measured at 3.5 GHz around were about 93, 6067 and 0 ppm/°C, respectively.     

Removal of paraquat in aqueous suspension of TiO<Subscript>2</Subscript> in an immersed UV photoreactor

Experiments were performed to investigate the effect of operating parameters on the photodegradation efficiency of paraquat in a TiO₂-suspended photoreactor with immersed UV lamps. TiO₂ particles were prepared by a hydrothermal method. The removal rate of paraquat in the reactor was 0.54 mg/l/h with only air-sparging. The removal rate in 24 h with both the UV radiation and air-sparging was 50% higher than that with only the UV radiation. Variations of the paraquat concentration at the UV intensities of 4 and 8 W/m₂ decreased slowly with time, but that at 12 W/m₂ decreased more rapidly. The removal efficiency at the air-sparging flow rate of 1 //min increased as a UV light intensity increased. pH value in the reactor at the UV intensity of 12 W/m₂ decreased with time until 12 h and then increased with time over 12 h.