Band 34, Heft 3

This review is an extension of our 2014 circulating fluidized bed (CFB) plenary lecture. A derivation of multiphase mass, momentum and energy balances is presented, with a review of elementary kinetic theory, to explain the concepts of granular temperature and pressure and the core-annular flow regime commonly observed in CFB. The kinetic theory shows that the particle concentration is given by the reciprocal of a fourth order parabola of dimensional tube radius, in agreement with experiments. Computed flow regimes and heat and mass transfer coefficients in fluidization are also discussed.

The nature of chemical product design problems is diverse and multidisciplinary. It involves many design issues such as project management, market study, product design, process design, and economic analysis for better organizing the product design project and achieving better products. This article provides an overview of chemical product design with a multidisciplinary hierarchical framework including all the design issues and tasks. Each of the design issues and tasks are introduced and discussed, methods and tools are summarized and compared, challenges and perspectives are presented to help the chemical product design researchers on finding more novel, innovative and sustainable products, by the combined effort from academia and industry to develop a systematic generic framework, and tools including product simulator, process simulator, database manager, modeling tool, and templates for design problems.

The interest in ionic liquids, particularly in polymerizable ionic liquids, is motivated by their unique properties, such as good thermal stability, negligible vapor pressure, and wide electrochemical window. Due to these features ionic liquids were proposed to be used in the membrane separation technology. The utilization of conventional ionic liquids is, however, limited by their release from the membrane during the given separation process. Therefore, the incorporation of polymerizable ionic liquids may overcome this drawback for the industrial application. This work is a comprehensive overview of the advances of ionic liquid membranes for the separation of various compounds, i.e. gases, organic compounds, and metal ions.

The advancement of research in colloidal systems has led to the increased application of this technology in more effective and targeted drug delivery. Nanotechnology enables control over functionality parameters and allows innovations in biodegradable, biocompatible, and stimuli-responsive delivery systems. The first closed bilayer phospholipid system, the liposome system, has been making steady progress over five decades of extensive research and has been efficient in achieving many desirable parameters such as remote drug loading, size-controlling measures, longer circulation half-lives, and triggered release. Liposome-mediated drug delivery has been successful in overcoming obstacles to cellular and tissue uptake of drugs with improved biodistribution in vitro and in vivo . These colloidal nanovehicles have moved on from a mere concept to clinical applications in various drug delivery systems for antifungal, antibiotic, and anticancer drugs.

This review focuses on the performance of immobilized cell bioreactors utilizing a magnetic field. These reactors utilized immobilized cells on magnetic particles or beads as the solid phase. All published research papers dealing with the performance of immobilized cell bioreactors utilizing a magnetic field from the early 1960s to the present time were considered and analyzed. It was noted that many microorganisms such as Saccharomyces cerevisiae were immobilized on different supports in these reactors. These papers used the magnetic field for several purposes, mainly for the stabilization of magnetic particles to prevent their washout from the column while operating with relatively high substrate flow rates to enhance mass transfer processes. It was observed that most publications used an axial magnetic field. In addition, most of the magnetic particles were prepared by entrapment. Some comments are presented at the end of the review which show the gaps in this promising application.

Carbon dioxide (CO 2 ) emission is one of the well-known causes of global warming. Photoconversion of CO 2 to useful chemical compounds using solar energy is an attractive approach as it reduces the major greenhouse gas and promises a sustainable energy source. This method involves radical-chain reactions that form cation and anion radicals generated as a result of the reaction with photogenerated electrons (e − ) and holes (h + ) between metal oxide photocatalyst and the reactants. Therefore, the product distribution of a modified photocatalyst even under specific reaction conditions is difficult to predict. The CO 2 photocatalytic reduction process is controlled by several conditions such as reactor configuration, photocatalyst type, and nature of the reducing agents. Here, we review the parameters such as temperature, pH, CO 2 pressure, type of reductant, role of co-catalysts, dopants, and type of photocatalysts that influence the end products of the photocatalytic reduction of CO 2 . In this review, the different modifications recommended for the photocatalysts to improve CO 2 reduction and receive maximum valuable end product (methane, ethanol, methanol, hydrogen, and carbon monoxide) have been listed. The discussion also includes specific behaviors of photocatalysts which lead to different product distribution. It has been noted that different metal and nonmetal dopants improve the activity of a photocatalyst and influence the end product distribution by altering the active species. Similarly, the key factors, i.e. size, morphology and doping, which have been ruling the photocatalytic activity of CO 2 reduction under UV or visible light irradiation have been identified.

In this review, the state of the art on the removal of malachite green dye from aqueous solution using adsorption technique is presented. The objective is to critically analyze different adsorbents available for malachite green dye removal. Hence, the available recent literature in the area is categorized according to the cost, feasibility, and availability of adsorbents. An extensive survey of the adsorbents, derived from various sources such as low cost biological materials, waste material from industry, agricultural waste, polymers, clays, nanomaterials, and magnetic materials, has been carried out. The review studies on different adsorption factors, such as pH, concentration, adsorbent dose, and temperature. The fitting of the adsorption data to various models, isotherms, and kinetic regimes is also reported.