Polyethylenimine-functionalized magnetic amorphous carbon fabricated from oil palm leaves as a novel adsorbent for Hg(II) from aqueous solutions

PEI (polyethylenimine) functionalized magnetic amorphous carbon thin film nano composite (Fe₃O₄-PEI-ACTF NC), was successfully synthesized and characterized by High Resolution Transmission Electron Microscope (HR-TEM), X-ray diffraction (XRD), Fourier-transform infrared spectrometer (FTIR), and Thermo gravimetric analysis (TGA). The synthesized nano composite Fe₃O₄-PEI-ACTF was developed as a highly efficient adsorbent for Hg(II) from aqueous samples. Effect of pH, contact time, adsorbent dose, initial concentration and temperature were investigated and optimized through batch adsorption technique. Besides, good magnetic performance of Fe₃O₄-PEI-ACTF NC makes it easily recovered from water with magnetic separation at low magnetic field. The adsorption kinetic data described well with the pseudo-second-order model and the equilibrium data fitted well to Langmuir isotherm model. The maximum adsorption capacity was 714?µg/g of Hg(II). Thermodynamic studies (ΔG°?<?0, ΔH°?>?0, ΔS°?>?0) implied an endothermic and spontaneous adsorption process in nature. Furthermore, the excellent reproducibility indicated that Fe₃O₄-PEI-ACTF NC has a promising application for removing heavy metals from aqueous environments due to high adsorption capacity and easily and quick separation.     

Base-catalyzed oxidation of poly (ethylene glycol) by alkaline permanganate: Part I. Kinetics and mechanism of formation of coordination intermediate complex

A spectrophotometric investigation has been applied to study the kinetics of oxidation of poly (ethylene glycol) (PEG) as a synthetic polymer by alkaline permanganate at a constant ionic strength of 1.0 mol.dm^?3. The reaction was found to proceed through two distinct measurable stages. The first stage was relatively fast and corresponding to the formation of coordination polymer intermediate complexes involving blue hypomanganate (V) and/or green manganate (VI) transient species. The influence of variable factors on the oxidation rates such as the concentration of permanganate ion and PEG substrate concentrations as well as the pH and ionic strength have been examined. Under the pseudo-first-order reaction conditions of [PEG] ? [MnO₄^?], the experimental results showed a first-order dependence in [MnO₄^?] and fractional first-order kinetics in each of [PEG] and alkali concentration. The oxidation process was of base-catalyzed nature where the oxidation rates were increased with increasing the alkali concentration. The observed first-order rate constant was found to be 1.1 ×10^?3 s^?1 with deprotonation constant of 0.72 dm³ mol^?1 at 45 °C. Blue hypomanganate (V) was detected for the first time by using a conventional spectrophotometer. The oxidation process has proceeded without the intervention of a free-radical mechanism. Colloidal manganese (IV) and the acid derivatives of PEG were identified as final oxidation products. The activation parameters of the second-order reaction have been calculated and found to be ΔH^≠ = 40.66 kJmol^?1; ΔS^≠ = ? 145.41 Jmo^l?K^?1 and ΔG^≠ = 83.99 kJmol^?1. A plausible reaction mechanism for oxidation based on the evaluated activation parameters and in good consistent with the observed kinetic data was suggested and discussed.     

16Mn(T/S 52K)螺旋缝埋弧焊钢管的H2S环境开裂性能

通过对16Mn(t／S52K)螺旋缝埋弧焊钢管在含H2S气田使用中所发生的破裂事故及实验室检测数据的分析，阐明了16Mn(T／S52K)螺旋缝埋弧焊钢管，其管体虽然能满足抗SSC要求，但由于锰、碳含量较高，具有淬硬倾向，不良的焊接行为，易产生对SSC敏感的马氏体组织。且管体和焊接热影响区对HIC十分敏感。因此不适宜用于输送含H2S天然气。