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Energies 2021, 14, 6805 41 of 72 solvents, such as crown ethers and cyclic siloxanes, have been shown to have selective reactivity with lithium and appear promising in the laboratory, but are still in the early phases of development (i.e., are low TRL). 2.5. Membrane Separations Technology Research on membrane separations in the context of direct lithium extraction include research on membranes that are specifically selective for allowing passage of lithium preferentially; less selective nanofiltration membranes that allow permeation of smaller monovalent ions, including lithium, but reject larger divalent ions; and membrane processes that remove water for concentration of all salts, including lithium [233–243]. Research on membranes that are designed to retain lithium by adsorption while allowing other ions to pass (e.g., [93]) is discussed in Section 2.3. Principles governing the function and design of membranes that allow selective lithium permeation have recently been reviewed and described [233,235]. Major factors governing the selectivity of ion channels for lithium include the size of the nanochannel relative to the hydrated and bare lithium-ion radius, the surface charge of the channel, and the morphology of the channel [235]. Lithium-selective membranes are still under fundamental investigation and have not been proposed for use to extract lithium from geothermal brines. Reverse osmosis (RO) and processes such as pervaporation can be used to concentrate lithium-containing brines [236,237]. RO serves the same function as evaporation or distilla- tion in lithium processing (i.e., water removal), to concentrate brines before precipitation or other concentration steps. RO is not selective for lithium or any salt. In most cases, RO and other energy-intensive water removal processes are proposed as improvements over time-consuming evaporation in ponds [236,238]. It is not apparent that RO will ever be economical to apply directly to geothermal brines, due to the high concentrations and complexity of salts in these brines, but water concentration processes are likely be used in the subsequent purification of geothermally derived lithium chloride solutions (see Section 3, below). As part of lithium recovery processes, membranes are often used or proposed for use to treat brines for the removal of divalent cations, metals, and other interfering substances be- fore the process of concentrating, precipitating or otherwise extracting lithium [63,233,234]. Rejection of other ions (i.e., not allowing them to pass the membrane) occurs via size exclu- sion, membrane surface charge, or other chemical and physical properties [233]. Nanofiltra- tion has been investigated extensively for the separation of lithium from magnesium and other interfering divalent cations [140,182,236,238–243]. For example, Wen et al. [239] used a spiral-wound Desal-5 DL 2540C membrane (GE Osmonics), which showed a 61–67% retention of the Mg2+, while Li+ passed through the membrane, giving a Li+/Mg2+ separa- tion factor of 3.5. In similar studies, commercial membranes designed for desalination were tested against lithium brines [236,239,242]. For example, the Desal-DK membrane (GE Osmonics) showed a Li+/ Mg2+ separation factor ranging between 2 and 3.2 depending upon the feed Li+ and Mg2+ concentrations and their ratio [236]. Other experiments include modification of membrane surfaces to change surface charge and other properties [182]. Variants on nanofiltration include hollow-fiber configurations [182,233]. Hollow-fiber fil- ters have advantages over a flat-sheet configuration in that the hollow fibers have a high packing density, lower energy and maintenance costs, and are easier to fabricate [182]. The rejection order of this composite hollow-fiber membrane was magnesium chloride (MgCl2) > magnesium sulfate (MgSO4) > NaCl ≥ LiCl [182,233]. Because commercially available nanofiltration membranes have been used for the separation of divalent cations from lithium, it is likely that nanofiltration will be incorporated into some process for the commercial separation of lithium from geothermal brines [133–135,143,157,238,244]. Because geothermal brines are typically extracted at high temperatures, thermally robust membranes are required. Preliminary results reported by Li et al. [182] showed thePDF Image | Recovery of Lithium from Geothermal Brines
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Product and Development Focus for Infinity Turbine
ORC Waste Heat Turbine and ORC System Build Plans: All turbine plans are $10,000 each. This allows you to build a system and then consider licensing for production after you have completed and tested a unit.Redox Flow Battery Technology: With the advent of the new USA tax credits for producing and selling batteries ($35/kW) we are focussing on a simple flow battery using shipping containers as the modular electrolyte storage units with tax credits up to $140,000 per system. Our main focus is on the salt battery. This battery can be used for both thermal and electrical storage applications. We call it the Cogeneration Battery or Cogen Battery. One project is converting salt (brine) based water conditioners to simultaneously produce power. In addition, there are many opportunities to extract Lithium from brine (salt lakes, groundwater, and producer water).Salt water or brine are huge sources for lithium. Most of the worlds lithium is acquired from a brine source. It's even in seawater in a low concentration. Brine is also a byproduct of huge powerplants, which can now use that as an electrolyte and a huge flow battery (which allows storage at the source).We welcome any business and equipment inquiries, as well as licensing our turbines for manufacturing.| CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com | RSS | AMP |