Degradation of bisphenol A by persulfate activation of MoS2 composite iron tailings.

In this paper, molybdenum disulfide was grown on the surface of iron-containing tailings by hydrothermal method, and a series of highly efficient activated persulfate (PMS) iron-based catalysts were successfully prepared. The results show that in the CTM 1-200/PMS system, the additional ratio of tailings and the hydrothermal temperature have important effects on the catalyst. The catalyst prepared under the conditions of CT:MoS2 (molar ratio 1:1) and hydrothermal temperature of 200 °C (CTM 1-200) had the best degradation effect on BPA, and the degradation effect was increased by four times. The reason for the improvement of degradation efficiency is that the introduction of MoS2 accelerates the REDOX cycle between Fe(II)/Fe(III), and the reduction of Fe(III) is mainly related to Mo(IV), while the reduction capacity of S is relatively weak. Molybdenum disulfide/iron tailing composite material provides a way for tailings to solve the problem of water pollution.

Recycling iron from pickling sludge to activate peroxydisulfate for the degradation of phenol.

In this work, iron was recovered from a kind of iron-rich pickling sludge by an acid leaching process, and the recycled iron was used as a catalyst to activate peroxydisulfate (PS) for the degradation of phenol. Different kinds of sludge catalysts were prepared by different drying methods such as ordinary drying (Ods), freeze drying (Fds) and vacuum drying (Vds). The degradation performance of the different catalysts/PS system under different conditions was explored, the vacuum drying sludge catalyst (Vds) has the best activity in a wide pH range (pH = 3-10) and a wide temperature range (0-40 °C). At the same time, the effect of a series of chelating agents (Oxalic acid (OA), Citric acid (CA), Tartaric acid (TA), Malic acid (DL-MA) and Ethylenediaminetetraacetic acid (EDTA)) on Vds/PS system was verified, and TA was selected as the best chelating agent to promote the degradation of the second stage where the degradation rate is limited. The quenching experiment and electron paramagnetic resonance (EPR) analysis indicated that hydroxyl radical (·OH) and sulfate radical (SO4̇-) were responsible for the abatement of the organic contaminant with ·OH playing a more important role. In summary, this study proposed an environmentally-friendly approach for the application of iron-rich pickling sludge in the remediation of phenol-contaminated water.

In-situ modified the surface of Pt-doped perovskite catalyst for soot oxidation.

In-situ modification is studied in this work on LaCo1-xPtxO3 for soot oxidation. A series of perovskite catalysts LaCo1-xPtxO3 (by sol-gel method) are modified with 30% H2O2. XRD, TEM, SEM, BET, XPS, Raman, in-situ DRIFTS, H2-TPR and TGA are used to investigate physicochemical properties of catalysts. TGA results show that all doped catalysts have a lower temperature of soot conversion, especially LaCo0.94Pt0.06O3 (T50 = 437 °C). The T50 of the catalyst with modification by H2O2 solution decreases at least 20 °C compared with the doped catalysts. A highly symmetrical structure and an obvious amorphous layer about 3-5 nm are observed in the modified catalysts. According to the XPS study, the symmetrical structure benefits to the movement of oxygen vacancy thus catalyst captures more adsorbed oxygen (about 95%). And the amorphous surface could adsorb more oxygen species. In addition, all catalysts show excellent aging resistance performance. The reaction mechanism of catalyst for soot oxidation is presented in the end.

Enhancing oxygen and hydrogen evolution activities of perovskite oxide LaCoO3 via effective doping of platinum.

In this study, a series of perovskite oxides LaCo1-x Pt x O3-δ (x = 0, 0.02, 0.04, 0.06, and 0.08) were prepared by the citric acid-ethylenediaminetetraacetic acid (CA-EDTA) complexing sol-gel method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Then, the samples were investigated as OER and HER bifunctional electrocatalysts in alkaline media. Compared with other catalysts, LaCo0.94Pt0.06O3-δ had good stability and presented more activity at a lower overpotential of 454 mV (at 10 mA cm-2), a lower Tafel slope value of 86 mV dec-1 and a higher mass activity of 44.4 A g-1 for OER; it displayed a lower overpotential of 294 mV (at -10 mA cm-2), a lower Tafel slope value of 148 mV dec-1 and a higher mass activity of -34.5 A g-1 for HER. The improved performance might depend on a larger ECSA, faster charge transfer rate and higher ratio of the highly oxidative oxygen species (O2 2-/O-). Furthermore, the eg orbital filling of Co approaching 1.2 in the B site might play a leading role.

Prediction of retention times in temperature programmed gas chromatography using the retention equation derived from crystallization behavior of polymer.

Based on the enlightenment from the crystallization behavior of polymer, a novel retention equation constructed with only three pairs of isothermal retention data was proposed to predict retention times in temperature programmed gas chromatography (TPGC). The new retention equation worked beautifully in both the single- and the multiple-ramp temperature-programmed modes, yielding the average absolute relative errors of 0.65% for single-ramp TPGC across all the 18 analytes in 3 temperature programmed experiments and 0.30% for multiple-ramp TPGC across all the 8 analytes in 6 temperature programmed experiments tested in this work. Moreover, to compare with the new retention equation systematically and thoroughly, another 13 retention equations determined by two or three parameters were derived from a universal formula lnk=a0+a1/T+a2/T²+a3 lnT+a4T+a5T² as a combination of the relationships between lnk and T with reference to four widely used retention equations in publications. Calculated by these 14 retention equations with the same experimental data, the absolute relative errors of prediction retention times for single-ramp TPGC mode were compared by means of statistical analysis. At a very high significance level of 1%, statistical evidences of paired t-test strictly implied that the new retention equation yielded the best prediction results among all of the 14 retention equations. In addition, remarkably, among the 13 retention equations, three seldom used in publications retention equations also worked nicely, yielding satisfactory average absolute relative errors of 0.78%, 0.81% and 0.84% for single-ramp TPGC.