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Abstract: In this paper we report about catalyst deactivation during reactions of 1-pentene over acidic ultrastable Y zeolite in a fixed-bed reactor. The effects of reaction temperature and time-on-stream (TOS) on product distribution, conversion and coke formation are discussed. At this work various coke groups – coke precursors, hard coke as well as total coke amount – were followed with TOS. Furthermore, the effects of coking on 1-pentene reactions were also studied. Cracking and hydride transfer were the predominant reactions in the first minute of TOS which deactivated rapidly allowing isomerisation to become the main reaction afterwards. A steep increase of the amount of coke formed was observed initially which was in good correlation with the initial rapid deactivation. The hydrogen freed during this initial time from the formation of high a carbon-to-hydrogen (C/H) ratio coke components contributed to the formation of hydride transfer products. [Copyright &y& Elsevier]

Abstract: Calcined Mg/Al hydrotalcite (CH-Mg/Al) and calcined Mg/Al vanadate hydrotalcite (CHV-Mg/Al) were prepared and characterized. Adsorption kinetics, effect of pH, equilibrium isotherms and the selectivity of both absorbents were assessed. The removal mechanism was studied by XRD, XPS and FTIR. The results showed that there was no redox reaction during the adsorption process. The adsorption process of CH-Mg/Al was mainly anion exchange and adsorption on external surface of the layers. The adsorption capacity of CHV-Mg/Al was mainly caused by ion exchange. The calcined Mg/Al hydrotalcite showed wonderful vanadium (V) adsorption capacity. Using vanadate to synthesize hydrotalcite was unfavorable to removal of vanadium (V) from aqueous solution. CHV-Mg/Al had highly selectivity of vanadium (V) in the mixed solution of vanadate and dichromate. Calcined hydrotalcites material has potential application for the removal of vanadium (V) from aqueous solution. [Copyright &y& Elsevier]

Highlights: [•] Protons released from phenol electrochemical oxidation degradation form hydrogen. [•] Three stages were observed in phenol electrochemical oxidation degradation at 3V. [•] Each stages could be well described by the first order kinetic model. [•] ICE increased in first two stages while decreased dramatically in third stage. [•] Hydrogen yield improved in first stage but reduced in second stage. [ABSTRACT FROM AUTHOR]

Abstract: Magnetic Fe3O4 particles modified sawdust (MCS) was prepared by using chitosan as the bridging reagent and characterized by FTIR analysis, and the results indicated that sawdust was successfully modified by magnetic Fe3O4 particles by connection of chitosan. The results obtained from the strontium ions adsorption experiments showed that the MCS was an effective material to remove strontium ions from aqueous solutions. And most importantly, the adsorption process was safely and easily controlled, the separation of MCS from solutions after adsorption was fast because of the magnetic modification. The adsorption of strontium ions by MCS was affected by pH, background electrolyte, adsorbent dosage and contact time. The adsorption process could achieve equilibrium in 30min, and the maximum adsorption capacity studied at different initial concentrations was 12.59mg/g. The adsorption process was a physical process which could be approved by the adsorption free energy and well fitted by the pseudo first order model. [Copyright &y& Elsevier]

Abstract: The potential of opal for removing crystal violet (CV) dye and reuse feasibility of opal-CV sludge for binding heavy metals from aqueous solutions were investigated. The adsorbent was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-Ray Diffraction (XRD) and the point of zero charge (pHpzc) analysis. The thermal treatment of opal at temperatures of 300, 400, 500, 700°C increased the pHpzc value from 6.6 to 7.4 and lead to a decrease in the adsorption of CV dye, demonstrating the significance of the functional groups spread over the surface of opal. The equilibrium adsorption data fitted well to the Freundlich model and the kinetic data conformed to the pseudo-second-order model. Intra-particle diffusion was not the sole rate-controlling factor. The maximum adsorption capacity of CV was found to be 101.13mgg−1 at 30°C. The activation energy (E a) of 13.85kJmol−1 indicated that the adsorption of CV onto opal was a physisorption. Thermodynamic parameters (ΔG Θ, ΔH Θ, and ΔS Θ) were evaluated and revealed that the adsorption process was spontaneous and endothermic in nature. Moreover, the opal-CV sludge was reutilized after calcination at 250°C (O-CV-250) for the removal of heavy metals from aqueous solution. The O-CV-250 had a maximum adsorption capacity of Pb(II) of 20.92mg·g−1 while has almost no adsorption of Ni(II) and Cr(VI). Enrichment of Pb(II) was conducted and almost 65% of the Pb(II) was collected. This work presents an effective approach for the treatment of dye wastewater and reutilization of dye sludge to enrich heavy metals. [Copyright &y& Elsevier]