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Energies 2021, 14, 6805 45 of 72 3.2. Modifications to Improve Sorbent Stability There are a number of recognized barriers to the application of lithium sorption for the recovery of lithium from geothermal brines. One limitation is the physical durability and chemical stability of the sorbent [259]. In order to be usable in geothermal systems, sorbents need to be thermally stable, resistant to harsh chemical conditions, and must be able to be regenerated multiple times [151]. In most applications, the sorbent must have physical characteristics, such as particle size, wettability, and porosity, that allow application in an ion-exchange column or a counter current exchanger [260]. Regeneration typically involved the treatment of the lithium-impregnated sorbent with an acid solution to desorb lithium by displacing and extracting the sorbed lithium ions with hydrogen ions. In the case of inorganic ion-exchange materials, dissolution and degradation of materials during uptake in brines is also an issue [259]. The number of times the sorbent can be reused and regenerated and the stability of the sorbent under geothermal brine conditions, including high temperatures, will be a major driver for determining the economic sustainability of any adsorption-based process. Several different approaches to stabilizing sorbents have been proposed. Snydacker [259] suggested coating MnOx sorbents to improve stability. Coating can be a variety of materials, such as phosphates, metal oxides, including titanium, nickel, and zirconium oxides, or carbon materials, including amorphous carbon [259]. Other suggested coatings include polymers, such as polystyrene and polydivinylbenzene, fluorides, fluoride polymers, and nitrides [259]. Ryu et al. [261] combined silica (SiO2) with lithium MnOx (Li1.33Mn1.67O4) by a high- energy milling technique and calcination in an effort to prevent manganese dissolution during acid regeneration. It was found that amorphous SiO2 imparted stability to the spinel MnOx and reduced the level of Mn dissolution during the acid extraction of sorbed lithium [261]. The silica-MnOx composite was tested for recovery of Li+ from lithium- spiked seawater and was found to have a sorption capacity of 43 mg/g [261], which is comparable to MnOx sorbents that are not in a matrix. Resins and polymers have been proposed for use to make more robust and stable vari- ants of metal oxide sorbents that can withstand repeated acid-extraction cycles [262–264]. Xiao et al. [264] made an ion-exchange bed sorbent synthesized from Li4Mn5O12 ultrafine powder in a polyvinyl chloride binder using N-methyl-2-pyrrolidone as solvent. Polymer nanofibers composed of hydrophilic polyacrylonitrile or polysulfone-based units have been used to stabilize MnOx sorbent and found enhanced lithium sorption attributed to reduced interference for alkaline earth metals [265,266]. Other suggested stabilizing approaches include other polymers, such as polystyrene and polydivinylbenzene, fluoride polymers, and sulfonate polymers [259,267,268]. Chitosan has been suggested as a sorbent matrix for MnOx sorbents [269]. MnOx in a chitosan matrix was determined to have a maximum adsorption capacity of 55 mg/g, which is higher than that reported for MnOx sorbents in a silica matrix [151,261]. Ryu et al. [269] investigated a continuous flow column packed with an MnOx adsorbent in a chitosan matrix. They tested the recyclability of this system after extraction of lithium from the adsorbent using sulfuric acid and found that the sorption capacity decreased slightly after recycling the adsorbent three times [269]. Chung and co-workers proposed a number of ideas for using stabilized sorbent for the passive or active extraction of lithium from seawater [266,270]. In one case, a specifically designed solid holder for lithium sorbent was developed to be placed on the seafloor or towed behind boats to collect lithium from seawater [270]. In another case, fabricated electrospun composite nanofiber was employed as an adsorbent membrane filter as part of a continuous lithium extraction process from seawater [266]. This membrane filter was composed of a hydrophilic polyacrylonitrile matrix infused with the lithium sorbent H1.6Mn1.6O4. This material was found to be mechanically suitable for use as a microfiltra- tion membrane and effective at capturing lithium even at a high water flux [266]. The filterPDF 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 |