Synthesis,characterisation of ternary layered double hydroxides (LDH) for sorption kinetics and thermodynamics of Cd2+

Kinetic and thermodynamic studies were carried out on the sorption of Cd²⁺ on three synthesised and characterised layered double hydroxides, namely: Ni-Co-Ti, Ni-Co-La and Mn-Ni-Al-CO₃. Sorption kinetics were investigated through time-dependent studies. Thermodynamics were determined by the effect of temperature on adsorption. Kinetic modelling of the adsorption of Cd(II) ions on the LDHs was determined using the first-order, pseudo-first order, pseudo-second order and Elovich kinetic models, as well as additional diffusion models. The results showed that the pseudo-second-order model best correlated the adsorption data with R² values of 1.000, 0.998 and 1.000 for NiCoTi, NiCoLa and MnNiAl-LDH respectively. Diffusion of the adsorbate was best correlated by the Weber-Morris intraparticle diffusion model with R² values of 0.9753, 0.8472 and 0.9412 for NiCoTi, NiCoLa and MnNiAl-LDH respectively. Thermodynamic studies showed that the adsorption was spontaneous and exothermic with a high probability of sticking.     

基于点阵式测量的混凝土箱梁水化热温度场原位试验

在混凝土箱梁模型上布设479个温度测点,对箱梁在水化热期间的温度变化规律进行精密测量。通过德洛内三角网格算法,建立用于混凝土箱梁温度测量的温度传感器点阵,绘制箱梁全截面在水化热期间的温度场云图,进而分析混凝土箱梁的水化热温度发展规律。研究结果表明：箱梁的水化热温度场基本呈对称分布,其中腹板水化热温度变化最大,最高温度为64.8℃,顶板、底板与腹板的最大平均温升比值约为1∶1.1∶1.4;底板水化热温度最先达到峰值,为混凝土浇筑后11h;腹板的平均温度峰值出现在浇筑后12h;顶板温度峰值相对滞后,为混凝土浇筑后13h;箱梁各板沿厚度方向的水化热温度服从高斯分布形式;顶板、底板沿宽度方向水化热温度呈双峰对称分布,服从二项组合式的高斯分布模型,而腹板的水化热温度沿板高可认为常量。此外,文中给出了箱梁模型关键位置在水化热期间的温度数据,可用于指导混凝土箱梁水化热温度试验的测点布置,并且为箱梁的水化热温度控制和设计提供参考。     

改性纳米SiO2对再生沥青胶结料性能的影响

为提高再生沥青的再生效果,文中采用RA-F0110型再生剂作为A型再生剂和OP-900型再生剂作为B型再生剂对旧沥青进行再生;采用硅烷偶联剂KH-550和KH-570对纳米SiO2进行有机化表面改性;对比不同速率、不同搅拌时间、不同静置时间下纳米再生沥青的PG高温分级温度,确定纳米再生沥青的制备方法;对比添加不同种类不同掺量再生剂后再生沥青的PG连续分级确定再生剂的种类和掺量;对比不同纳米SiO2掺量下纳米再生沥青的PG连续分级确定纳米材料的掺量。试验表明：纳米SiO2在表面改性后团聚现象减少。纳米粒子被包覆,所以纳米粒子尺寸增大导致单个粒子的比表面积明显减小,纳米SiO2在沥青中更加稳定,采用KH-550表面改性剂的效果优于KH-570。选用A型再生剂的再生沥青的再生效果优于选用B型再生剂的再生沥青。在相同再生剂掺量下,添加一定比例的纳米SiO2,纳米再生沥青PG连续分级的高低温服务范围更宽广。当纳米材料的掺量为5%,A型再生剂掺量为15%时,纳米再生沥青胶结料的性能指标达到最佳。     

电晕处理对聚乙烯薄膜热封性能的影响

聚乙烯薄膜经过电晕处理后,热封温度提高,热封强度降低。这可通过降低电晕处理强度,适当延长热封时间和添加一定比例的mLLDPE树脂,以减小电晕处理对聚乙烯薄膜热封性能的影响。     

创新型处理高污染废水的低温常压蒸发技术

农药废水对环境造成严重污染。农药废水处理旨在降低农药生产废水中污染物浓度,提高回收利用率,从而尽量达到无害化。创源环保(CWT)公司开发的低温常压蒸发工艺能在处理废水时实现大幅地低能耗运行和低维护成本,同时也提高了回收废水中有价值的物质的可能性。     

三元共聚多孔丙烯酸酯类吸油树脂的合成及性能研究

以丙烯酸酯类为单体、苯乙烯为主要共聚功能单体,二乙烯基苯为交联剂,三氯甲烷为致孔剂,采用悬浮共聚工艺合成了一系列多孔的高吸油树脂。着重研究了树脂共聚单体组成、交联剂加量、引发剂用量以及分散剂加量等因素对吸油树脂吸油性能的影响。在最优化合成条件下制备的高吸油树脂具有较佳的吸油性能,对甲苯的吸附量可达32 g/g。     

氯醋树脂汽提工艺改进

针对氯醋树脂正压汽提系统运行时出现的脱吸温度高、树脂黏性大、装置频繁停车等问题进行了改造,增加了真空机组,使汽提系统在负压下运行,降低了汽提温度,节省了蒸汽用量,提高了氯醋树脂的产品质量,保证了系统的平稳运行。     

The Effect of NaCl on the Krafft Temperature and Related Behavior of Cetyltrimethylammonium Bromide in Aqueous Solution

This paper presents the effect of NaCl on the Krafft temperature (T _K), surface adsorption and bulk micellization of cetyltrimethylammonium bromide (CTAB) in aqueous solution. The critical micelle concentration (CMC) of CTAB in the presence of NaCl increased and then decreased with increasing temperature. Thus, the CMC–temperature data can be represented by a bell-shaped curve. The micellar dissociation (fraction of counterion binding) and energetic parameters (free energy, enthalpy and entropy changes) of both adsorption and micellization were calculated. The processes were found to be both enthalpy and entropy controlled and appeared to be more and more enthalpy driven with increasing temperature. An enthalpy–entropy compensation rule was observed for both adsorption and micelle formation. The T _K of the surfactant decreased significantly in the presence of NaCl, which is a sharp contrast to the usual behavior of the effect of electrolytes on the T _K of classical ionic surfactants. The surface excess concentrations decreased with increasing temperature. However, the values were much higher in the presence of NaCl compared to the corresponding values in pure water. The solubilization behavior of a water-insoluble dye, Sudan red B (SRB), in the micellar system was studied by the UV–visible spectrophotometric technique. The molar solubilization ratio in the presence of NaCl was found to be about three times higher than that in pure water, indicating that the solubilization of SRB in the CTAB micelles significantly increases in the presence of NaCl.     

Fracture toughness improvement of epoxy resins with short carbon fibers

This study examined the thermal stability and fracture toughness of diglycidylether of bisphenol-A (DGEBA)/short carbon fiber (SCF) composites using several techniques. The thermal stability of the DGEBA/SCF composites was similar to that of neat epoxy resin. The fracture toughness of the composites was significantly improved relative to the neat resin. The SEM micrographs indicated that a relatively rough surface with shear deformation and tortuous cracks was formed, thereby preventing deformation and crack propagation and inducing higher fracture toughness in the DGEBA/SCF composites.