Water transport, liquid-solid systems

Liquid-Solid Systems In liquid-solid systems, such as solids treated in hypertonic solutions, two main forms of mass transport can be identified (i) water moving from the solid tissue to the solution and (ii) solutes moving from the solution into the solid. Both fluxes must overcome the internal resistance to mass transfer in the interior of the treated solids, and the external resistance between the solid surface and the surrounding liquid. 

STABREX is easier and simpler to use compared to any other oxidant available for industrial water treatment. The product is pumped directly from returnable transporters (PortaFeed Systems)17 with standard chemical feed equipment. Previously, the only practical ways to apply bromine were to oxidize bromide solutions on-site with chlorine in dual liquid feed systems, or with one of the solid organically-stabilized bromine products applied from sidestream erosion feeders. The former is cumbersome and complex, and the latter is prone to dusting and difficult to control. Other oxidants require complex handling and feed of toxic volatile gases, unstable liquids, multiple-component products, or reactive solids. Simplicity in use results in reduced risk to workers and to the environment. 

Pipelines to transport solids are called freight pipelines, of which three different types exist pneumatic pipelines, the use of which is known as pneumotransport or pneumatic conveying slurry pipelines, which may also be called hydrotransport or hydraulic conveying and capsule pipelines. When air or inert gas is used to move the solids in the pipeline, the system is called a pneumatic pipeline and often involves a wheeled vehicle inside the pipeline, propelled by air moving through the pipe (25). Slurry pipelines involve the transport of solid particles suspended in water or another inert liquid. Hydraulic capsule pipelines transport solid material within cylindrical containers, using water flow through the pipeline for propulsion. 

Water is a crucial part of the three-phase, solid-liquid-gas system making up soil. It is the solvent of the soil solution (see Section 2.6) and is the basic transport medium for carrying plant nutrients from solid soil particles into plant roots and to the farthest reaches of the plant s leaf structure (Figure 2.8). The water enters the atmosphere from the plant s leaves, a process called transpiration. Large quantities of water are required for the production of most plant materials. 

Gas-to-liquid mass transfer is a transport phenomenon that involves the transfer of a component (or multiple components) between gas and liquid phases. Gas-liquid contactors, such as gas-liquid absorption/ stripping columns, gas-liquid-solid fluidized beds, airlift reactors, gas bubble reactors, and trickle-bed reactors (TBRs) are frequently encountered in chemical industry. Gas-to-liquid mass transfer is also applied in environmental control systems, e.g., aeration in wastewater treatment where oxygen is transferred from air to water, trickle-bed filters, and scrubbers for the removal of volatile organic compounds. In addition, gas-to-liquid mass transfer is an important factor in gas-liquid emulsion polymerization, and the rate of polymerization could, thus, be enhanced significantly by mechanical agitation. 

A significant difficulty in characterizing and quantifying gas-liquid, liquid-solid, and gas-liquid-solid mixtures commonly found in bioreactor flows is that the systems are typically opaque (e.g., even an air-water system becomes opaque at fairly low volumetric gas fractions) this necessitates the use of specially designed invasive measurement probes or noninvasive techniques when determining internal flow and transport characteristics. Many of these probes or techniques were developed for a particular type of gas-liquid flow or bioreactor. This chapter first introduces experimental techniques to gauge bioreactor hydrodynamics and then summarizes gas-liquid mass transfer measurement techniques used in bioreactors. 

The diffusion coefficient of holes via the I /l3 redox couple in the solid containing 2.5 wt % carrageenan, 0.3 M KI, 0.03 MI2, and excess water was investigated by an impedance spectroscopy it was ca. 1.7 x 10 cm s , which is almost the same as that in liquid water, showing that the hole transport in the solid is not a problem in comparison with the liquid medium system. Similar results have been obtained also for a solid containing redox electrolyte and organic liquid [57]. In the present solid material, transport of small ions and molecules takes place in the same way as in a liquid, showing that the liquid contained in this solid behaves as if it were a pure liquid. 

Movements of liquid water within porous solids have been experimentally observed. Haines studied the movement of liquid water within porous media during drying [26, 27]. He observed rapid movements of water elements in the porous system (Haines jumps). The capillary pressure transports water to narrow pores at the surface. Larger volumes surrounded by narrow pores can be rapidly emptied, and smaller volumes can be filled when the water is removed out of the narrow... 

The overall reaction in an electrochemical cell never contains electrons. In the example above, the electrons produced from oxidizing water flow in the external circuit to the cathode and are consumed in the reduction of cupric ions. To complete the external circuit, charge must be able to flow through the solution. That charge is carried by the transport of ions. A medium with mobile charge carriers is termed an electrolyte. Electrolytes are typically liquids, but systems can contain solid electrolytes if they are able to sustain the transport of charged species. 

Phase transfer catalysis (PTC) refers to the transfer of ions or organic molecules between two liquid phases (usually water/organic) or a liquid and a solid phase using a catalyst as a transport shuttle. The most common system encountered is water/organic, hence the catalyst must have an appropriate hydrophilic/lipophilic balance to enable it to have compatibility with both phases. The most useful catalysts for these systems are quaternary ammonium salts. Commonly used catalysts for solid-liquid systems are crown ethers and poly glycol ethers. Starks (Figure 4.5) developed the mode of action of PTC in the 1970s. In its most simple... 

The presence of water as solid, liquid, and gas is a feature that makes Earth unique in the solar system and that makes life possible as we know it. The transport of water and the energy exchanged as it is converted from one state to another are important drivers in our weather and climate. One of the key missions is to develop a better understanding of the global water cycle at a variety of scales so that we can improve model forecasts of climate trends,... 

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