Effective and highly recyclable ceramic membrane based on amorphous nanosilica for dye removal from t

In this study, an adsorptive ceramic membrane was prepared by a simple dry pressing of a mixture of nanosilica produced from low cost rice husk by hydrothermal technique at sub-critical water conditions, calcium phosphate, and ammonium acetate together and then calcined at 600 °C in air. Optimization of the raw materials ratio was found to be necessary to avoid crack formation during sintering process. The membrane microstructure, dye removal efficiency and the permeation flux of the membranes were investigated. The membrane was tested to remove the methylene blue from aqueous solution. Results show that the removal of the dye increases as the silica content increases in the all given membranes and it decreases with an increase in the ammonium acetate. Moreover, the water flux decreases with an increase in the silica content. The methylene blue adsorbed onto the silica membrane can be removed by calcination and the membrane could be recycled several times without any obvious loss in the adsorption performance. In conclusion, this study demonstrates a convenient strategy to prepare an effective adsorptive membrane, which can be applied as a highly recyclable membrane for the adsorption of organic maters

Geological and Tectonic Setting of Andesitic Rock in Central Eastern Desert, Egypt

Objective. e current study aims to detect the geologic features, geochemical characteristics and tectonic setting of the investigated rock using eld observations and geochemical analyses. Research methods. is work contains both eld work (Collection samples and drawing of a new geological map) and laboratory work (preparation of thin sections for petrographic studies by polarizing microscope), X-ray Fluorescence analysis (XRF) in Institute of Biology, Southern Federal University and Mass-Spectrometer with Inductively Coupled Plasma (ICPMS) at the central Laboratory of Russian Geological Institute. Result. Investigated andesitic rock belongs to Dokhan volcanic that located in the Central Eastern Desert of Egypt a long Qena-Safaga Road. It is considered as one of the most important shear zones in Eastern Desert that includes distinctive rocks and economic mineral deposits. e investigated rock belongs to late to post tectonic magmatism of the East African Orogeny (EAO). Petrographically: Dokhan volcanic is represented by andesite according to petrographical studies. It consists of plagioclase, quartz, in addition to ma c minerals. Geochemically, the investigated andesite samples plotted in calk-alkaline nature. Conclusion. Tectonically, andesite samples fall in arc lava and continental elds. ey are enriched in Ba, Sr, Rb, K, Nb and Ce with marked depletion in the most HFSEs like those of island arc calc-alkaline series.Цель. Настоящее исследование направлено на выявление геологических особенностей, геохимических характеристик и тектонических условий исследуемой породы с помощью полевых наблюдений и геохимического анализа. Методы исследования включают в себя как полевые (сбор образцов и составление новой геологической карты), так и лабораторные работы (подготовка тонких разрезов для петрографических исследований с помощью поляризационного микроскопа), атомную абсорбцию, рентгеновский флуоресцентный анализ (XRF) Геологическое и тектоническое положение андезитов и масс-спектрометрия с индуктивно связанной плазмой (ICP-MS) в лаборатории Геологического института РАН. Результат. Исследуемая андезитовая порода относится к вулкану Дохан, который расположен в Центрально-Восточной пустыне Египта, по дороге Кения-Сафага. Он считается одной из важнейших зон сдвига в Восточной пустыне, которая включает в себя отличительные породы и экономические месторождения полезных ископаемых. Исследуемая порода относится к позднему посттектоническому магматизму восточноафриканской орогении (EAO). Вулкан Дохан сложен андезитом по петрографическим исследованиям. Он состоит из плагиоклаза, кварца в дополнение к мафическим минералам. Геохимически исследованные образцы андезита имеют известково-щелочную природу. Заключение. Тектонически, андезит попадает в поля островодужных и континентальных базальтов. Они обогащены Ba, Sr, Rb, K2 O и Zr с заметным обеднением большинства HFSE, таких как известково-щелочные островодужные серии

The Emergent "System" of Global Environmental Governance

A de facto "system" of global environmental governance already exists. The de facto system of global environmental governance is neither neat nor simple; it works in a rather messy, non-linear, non-hierarchical, and intertwined fashion. However it is a system that has proved to be resilient as well as prolific. This paper argues that although there is no real reason to make the system less messy, it can be made more effective by taking a number of steps that would (a) support the positive trends already apparent in the emergent system (b) strengthen the system as it evolves, and (c) articulate a clear vision for the eventual system that we wish to move towards. Copyright (c) 2004 Massachusetts Institute of Technology.