Volume 32, Issue 5

Palm kernel shell (PKS) is one of the greatly abundant residues in the palm oil industry. It possesses physiochemical characteristics that build in it a potential to serve the production of valuable products, namely, bio-fuels such as char, bio-oil, and bio-gas. This paper presents the properties of PKS as a biomass feed for the production of char. Characterizations of PKS in terms of proximate and ultimate analyses, chemical composition, and higher heating value (HHV in terms of MJ/kg) are presented and consequently compared to different oil palm biomass such as empty fruit bunch (EFB), fiber, fronds, and trunks. To illustrate and signify stability, the aforementioned characteristics are discussed for PKS-char, along with further comparison with EFB-char and coal. In addition, recent advances in char production methods from PKS are presented and compared. Simultaneously, future prospects and major challenges towards the utilization of PKS for the production of char are also addressed.

Standard drug delivery systems for cancer treatment usually comprise a device with a specific size and shape (depending on the type of cancer that has to be treated), which is composed by a biodegradable compound with a chemotherapeutic entrapped within it. This device should have a molecule (mainly a protein) bound to its surface to target only cancer cells. On the contrary, supercritical fluids (SCF) have been widely used in the pharmaceutical industry for creating drug delivery systems or for extracting drugs from natural sources. This review explains the potential of SCFs for cancer therapies by studying the current uses of the different high-pressure processes that can be useful for this medical treatment, such as the development of new drug delivery systems (with their drug release) or the extraction of chemotherapeutics from a vegetal matrix.

In populated, water-scarce regions, seawater and wastewater are considered as potable water resources that require extensive treatment before being suitable for consumption. The separation of water from salt, organic, and inorganic matter is most commonly done through membrane separation processes. Because of permeate flux and concentration polarization, membranes are prone to fouling, resulting in a decline in membrane performance and increased energy demands. As the physical and chemical properties of commercially available membranes (polymeric and ceramic) are relatively static and insensitive to changes in the environment, there is a need for stimuli-reactive membranes with controlled, tunable surface and transport properties to decrease fouling and control membrane properties such as hydrophilicity and permselectivity. In this review, we first describe the application of electricity-conducting and electricity-responsive membranes (ERMs) for fouling mitigation. We discuss their ability to reduce organic, inorganic, and biological fouling by several mechanisms, including control over the membrane’s surface morphology, electrostatic rejection, piezoelectric vibrations, electrochemical reactions, and local pH changes. Next, we examine the use of ERMs for permselectivity modification, which allows for the optimization of rejection and control over ion transport through the application of electrical potentials and the use of electrostatically charged membrane surfaces. In addition, electrochemical reactions coupled with membrane filtration are examined, including electro-oxidation and electro-Fenton reactions, demonstrating the capability of ERMs to electro-oxidize organic contaminates with high efficiency due to high surface area and reduced mass diffusion limitations. When applicable, ERM applications are compared with commercial membranes in terms of energy consumptions. We conclude with a brief discussion regarding the future directions of ERMs and provide examples of several applications such as pore size and selectivity control, electrowettability, and capacitive deionization. To provide the reader with the current state of knowledge, the review focuses on research published in the last 5 years.

In a nonequilibrium multiphase system, the Marangoni effect has important influence on interphase heat and mass transfer induced by interfacial tension gradient associated with either solutal or thermal gradients in numerous applications. Although the basic knowledge of the Marangoni effect has made great progress, its mechanism is not yet fully recognized. An in-depth understanding of the basic principles of heat and mass transport induced by the Marangoni effect is important for better operation of interphase transfer units. This report aims to provide a systematic study of the mechanisms of the Marangoni effect. Special foci are concentrated on the field of material processing, which encompasses the process wherein the raw materials are transformed into useful engineering products. A series of experimental, theoretical, or simulated results are extracted from the literature to elucidate the mechanism of the Marangoni effect and to rationalize the interphase transport phenomena. We examine the major physical explanations and attempt to distinguish the working principle behind the process. Perspectives are also proposed to trigger further innovative thinking about the topics. This work provides new insight into material processing by taking advantage of the Marangoni effect and has far-reaching implications in the design of future nonequilibrium multiphase system.