Transformation of macromonomers into ring‐opening polymerization macroinitiators: A detailed initiation efficiency study

In the present study, n‐butyl acrylate macromonomer (BAMM) (M_n = 1900 g mol^?1; PDI = 1.96) has been synthesized via a high‐temperature polymerization process. Subsequently, the olefinic termini of the BAMM have been transformed into a diol via a dihydroxylation process using KMnO₄ as an oxidizing agent. The OH‐terminated macroinitiator pBA(OH)₂ has subsequently been employed for the ring‐opening polymerization (ROP) of ε‐caprolactone via various catalytic systems, that is, organo‐(1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene), metal (tin(II) 2‐ethylhexanoate), and enzymatic catalysis (Novozym® 435). The obtained pBA‐b‐pCL block copolymers and the initiation efficiency of the BAMM macroinitiator have been investigated via size exclusion chromatography (SEC), electrospray ionization–mass spectrometry (ESI‐MS) hyphenated with SEC and liquid chromatography at the critical conditions of both poly(ε‐caprolactone) (pCL) and pBA. The in vitro enzyme catalysis (eROP) approach proved to be the most efficient catalysis system due to minor transesterification side reactions during the polymerization process. However, side reactions such as transesterifications occur in each catalytic system and—while they cannot be suppressed—they can be minimized. The species generated during the eROP process include the desired block copolymer pBA‐b‐pCL as main species as well as pCL homopolymer and residual macroinitiator pBA(OH)₂. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Copolymerization of styrene and norbornene with β‐diketiminato nickel/methylaluminoxane catalytic system

Styrene–norbornene (S‐N) copolymerizations were carried out using β‐diketiminato nickel complexes CH{C(CF₃)NAr}₂NiBr (Ar = 2,6‐ⁱPr₂C₆H₃, 1 ; Ar = 2,6‐Me₂C₆H₃, 2 ) in the presence of methylaluminoxane. The influence of the comonomer feed content and polymerization temperature on the conversion and composition of the copolymers with the catalytic system was investigated. An increase in the feed ratio of S/N led to an increase in the incorporated styrene content of the resulting copolymer. NMR characterization of the copolymers generated with the catalytic systems showed that the random S‐N copolymers are produced. Differential scanning calorimetric determination of the copolymers shows higher T_g values than polystyrene, and gel permeation chromatographic measurements have shown that the copolymers possess rather narrow molecular weight distributions, suggesting that the copolymerization take place at a single active site. Copyright © 2012 John Wiley & Sons, Ltd.     

ICP－AES法分析水质的探讨

本文用ＩＣＰ－ＡＥＳ（电感耦合等离子体－原子发射光谱法）测定水中Ａｌ、Ｂ、Ｂａ、Ｂｅ、Ｃａ、Ｃｄ、Ｃｏ、Ｃｒ、Ｃｕ、Ｆｅ、Ｍｇ、Ｍｏ、Ｍｎ、Ｎｉ、Ｐｂ、Ｓｒ、Ｖ、Ｚｎ等１８种微量元素。方法简便、快速，只将样品简单酸化，即可测定。方法检出限为０．０００５－０．５μｇ／ｍＬ。相对标准偏差＜１８％     

Removal of field-collected Microcystis aeruginosa in pilot-scale by a jet pump cavitation reactor

Hydrodynamic cavitation has been investigated extensively in the field of water treatment in the last decade and a well-designed hydrodynamic cavitation reactor is critical to the efficient removal of algal and large-scale application. In this paper, a jet pump cavitation reactor (JPCR) is developed for the removal of cyanobacteria Microcystis aeruginos in a pilot scale. The results demonstrate that the photosynthetic activity of M. aeruginosa is greatly inhibited immediately after treatment in the JPCR, and the growth is also hindered after 3 days culture. Moreover, a high cell disruptions of M. aeruginosa is detected after treated by JPCR. The release of chlorophyll-a indicates that the JPCR caused serious rupture to M. aeruginosa cells. The plausible cell disruption mechanisms are proposed in accordance with a fluorescence microscope and scanning electron microscope. Then, the optimization of cell disruption efficiency is also investigated for various operating conditions. The results showed that the algal cell disruption efficiency is improved at higher inlet pressure and the cavitation stage between the unstable limited operation cavitation stage and stable limited operation cavitation stage. The effect and optimization of JPCR on algal reduction are highlighted. The results of the study promote the application of hydrodynamic cavitation on algal removal and provide strong support for JPCR application in algal removal.     

Greener organic synthetic methods: Sonochemistry and heterogeneous catalysis promoted multicomponent reactions

Ultrasound is an essential technique to improve organic synthesis from the point of view of green chemistry, as it can promote better yields and selectivities, in addition to shorter reaction times when compared to the conventional methods. Heterogeneous catalysis is another pillar of sustainable chemistry being the recycling and reuse of the catalysts one of its great advantage. In the other hand, multicomponent reactions provide the synthesis of structurally diverse compounds, in a one-pot fashion, without isolation and purification of intermediates. Thus, the combination of these protocols has proved to be a powerful tool to obtain biologically active organic compounds with lower costs, time and energy consumption. Herein, we provide a comprehensive overview of advances on methods of organic synthesis that have been reported over the past ten years with focus on ultrasound-assisted multicomponent reactions under heterogeneous catalysis. In particular, we present pharmacologically important N- and O-heterocyclic compounds, considering their synthetic methods using green solvents, and catalyst recycling.     

Sonocatalytic degradation of EDTA in the presence of Ti and Ti@TiO2 nanoparticles

The sonocatalytic degradation of EDTA (C₀ = 5 10⁻³ M) in aqueous solutions was studied under 345 kHz (P_ac = 0.25 W mL⁻¹) ultrasound at 22–51 °C, Ar/20%O₂, Ar or air, and in the presence of metallic titanium (Ti⁰) or core-shell Ti@TiO₂ nanoparticles (NPs). Ti@TiO₂ NPs have been obtained using simultaneous action of hydrothermal conditions (100–214 °C, autogenic pressure P = 1.0–19.0 bar) and 20 kHz ultrasound, called sonohydrothermal (SHT) treatment, on Ti⁰ NPs in pure water. Ti⁰ is composed of quasi-spherical particles (30–150 nm) of metallic titanium coated with a metastable titanium suboxide Ti₃O. SHT treatment at 150–214 °C leads to the oxidation of Ti₃O and partial oxidation of Ti⁰ and formation of nanocrystalline shell (10–20 nm) composed of TiO₂ anatase. It was found that Ti⁰ NPs do not exhibit catalytic activity in the absence of ultrasound. Moreover, Ti⁰ NPs remain inactive under ultrasound in the absence of oxygen. However, significant acceleration of EDTA degradation was achieved during sonication in the presence of Ti⁰ NPs and Ar/20%O₂ gas mixture. Coating of Ti⁰ with TiO₂ nanocrystalline shell reduces sonocatalytic activity. Pristine TiO₂ anatase nanoparticles do not show a sonocatalytic activity in studied system. Suggested mechanism of EDTA sonocatalytic degradation involves two reaction pathways: (i) sonochemical oxidation of EDTA by OH/HO₂ radicals in solution and (ii) EDTA oxidation at the surface of Ti⁰ NPs in the presence of oxygen activated by cavitation event. Ultrasonic activation most probably occurs due to the local heating of Ti⁰/O₂ species at cavitation bubble/solution interface.     

Flame Emission Spectrometry Using Atomic Absorption Apparatus (I) Determination of Sr In Sea Water

Flame emission determination of Sr in sea water is studied using an ordinary atomic absorption apparatus. The analytical line 4607 A is used with background correction at 4616 A. The ionization is found to be negligible in air acetylene flame with sea water, and the interference of H₂SO₄ is elimentated using the higher part of the flame.     

Estimation of lake water—groundwater interactions in meromictic mining lakes by modelling isotope signatures of lake water

Abstract

A method is presented to assess lake water–groundwater interactions by modelling isotope signatures of lake water using meteorological parameters and field data. The modelling of δ¹⁸O and δD variations offers information about the groundwater influx into a meromictic Lusatian mining lake. Therefore, a water balance model is combined with an isotope water balance model to estimate analogies between simulated and measured isotope signatures within the lake water body. The model is operated with different evaporation rates to predict δ¹⁸O and δD values in a lake that is only controlled by weather conditions with neither groundwater inflow nor outflow. Comparisons between modelled and measured isotope values show whether the lake is fed by the groundwater or not. Furthermore, our investigations show that an adaptation of the Craig and Gordon model [H. Craig, L.I. Gordon. Deuterium and oxygen-18 variations in the ocean and the marine atmosphere. In Stable Isotopes in Oceanographic Studies and Paleotemperature, Spoleto, E. Tongiorgi (Ed.), pp. 9–130, Consiglio Nazionale delle Ricerche, Laboratorio di Geologia Nucleare, Pisa (1965).] to specific conditions in temperate regions seems necessary.     

Methodik und Ergebnisse von Tracerexperimenten über katalytische Reaktionen von Kohlenwasserstoffen

Tracermethoden können wichtige Beiträge zur Aufklärung katalytischer Kohlenwasserstoffreaktionen liefern. In dieser Arbeit werden einige Ergebnisse mehrjähriger Untersuchungen mit ¹⁴C-markierten Verbindungen zusammenfassend dargestellt. Es wird speziell auf Benzenbildungsreaktionen bei der Leichtbenzin-Reformierung und auf Reaktionsmechanismen bei der Isomerísierung von C₈-Aromaten eingegangen.