Reticle Inc


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The Reticle Carbon Material

Reticle has discovered, patented, and developed a novel manufacturing process for making activated carbon electrode (ACE) material, a process that has proven to be consistent and inexpensive. The Reticle process converts activated carbon material into solid monolithic form ideally suited for use as CDI electrodes and preserves most of the surface area intrinsic in the original activated carbon in the final monolith. To maximize surface area in the Reticle CarbonŠ monolith, we select precursor activated carbon material with very high intrinsic surface area. (We determine the active adsorption area in our prospective precursor material using BET analysis. (BET is the analytical method of determining the surface area of a material by measuring the monolayer adsorption of nitrogen on a surface.) Commercial activated carbon is available in surface areas ranging from 1500 m2/g to 3000 m2/g). The Reticle process (which will not be disclosed here) is able to preserve approximately 85-90 percent of the surface area of the activated carbon from which it is made, allowing solid, monolithic electrodes with surface areas in the range of 1200 m2/g to 2500 m2/g. Such ultra high surface area electrodes offer exceptional properties for ion removal from dilute or concentrated solutions. The Reticle CarbonŠ manufacturing process is flexible so that we can tailor the material to a specific attribute. For example, our material can be manufactured so that we get the maximum conductivity, surface area, or regeneration time depending on the application driven conditions that are required. It is not always the objective to blindly maximize surface area or blindly maximize conductivity.

The Reticle CarbonŠ material exhibits a number of unique and important properties, as outlined below:

  • Reticle CarbonŠ electrode material exhibits dramatically superior surface area properties as compared to previously existing, commercial ACE materials (e.g., Aerogels or xerogels from carbonization of advanced materials as well as electrodes made from carbon particles held together with binders). Aerogel carbon (from Lawrence Livermore National Laboratory) has the best properties of all materials reported to date, with surface areas claimed "on paper" to be as high as 800 m2/g but not measured in commercial electrodes at levels higher than 400 m2/g. Reticle CarbonŠ electrode materials have consistently exhibited surface areas from 1200 m2/g to 2500 m2/g. (Reticle can provide independent third party validated BET surface area measurements.) To wit, the Reticle CarbonŠ offers 3 to 6 times the electrode surface area as the current "best in class" electrode material.

  • Reticle CarbonŠ is a rigid, solid material that provides unique improvements in cell design. Aerogel is manufactured on structurally flimsy, conductive, paper-thin sheets of carbon cloth. Metal current collector plates must be used to support Aerogel electrodes. Additionally, it should be understood that the wafer thin aerogel electrodes actually have a very small mass of activated carbon deposited on their surfaces. Consequently, a large number of electrodes are needed to have enough carbon mass, and therefore enough surface area, to be able to treat a significant amount of water economically. Because we can make our monolithic slices of Reticle CarbonŠ in any thickness we like, any mass (or any total surface area) of Reticle CarbonŠ can be placed within a CDI cell. As a result, the number of Reticle CarbonŠ electrodes required will be much smaller than would be required for an Aerogel/metal configuration. Reticle requires fewer electrodes, fewer electricity source-electrode connections, and therefore more efficient use and smaller size of the electrical source.

  • Reticle CarbonŠ electrode material exhibits superior conductivities to all others. Binder carbon electrodes have reported electrical resistivities (inverse conductivities) of approximately 10 W cm. Reticle CarbonŠ electrodes, on the other hand, have resistivities ranging from 0.04-0.134 W cm; Reticle CarbonŠ is by far the more efficient electrode material.

  • Reticle CarbonŠ electrode material has proven to be much cheaper to manufacture than other carbon electrode material. Aerogel, binder carbon, and xerogel carbon electrode materials cost at least $145/kg to manufacture, while the Reticle CarbonŠ electrode material costs only about $20-40/kg in the sub-commercial quantities we have used to date. Commercial scale quantities promise to cut that cost by substantially more than half. In light of the fact that one needs substantially more of other carbon electrodes than Reticle CarbonŠ per gallon of water treated and that the other carbons cost over 7 times as much as Reticle, Reticle CarbonŠ holds in excess of a ten-fold cost advantage when compared on a cost per gallon of production basis.

  • In deionization tests, the Reticle CarbonŠ electrode material has demonstrated higher ion retention capacity, allowed much higher water flow, and could be regenerated in about 1/3 the time it takes to regenerate a comparable Aerogel apparatus. For example, in deionization applications, Reticle CarbonŠ electrodes readily removed 500 ppm salt from water and consumed less than 0.4 watt-hours per liter in so doing. This rather spectacular performance using feedwater in the mid-salinity range convinced us that Reticle CarbonŠ may well be the missing link to the water treatment chain—the link that allows one to quickly and economically purify ion-laden water to drinking water at much lower cost than has been possible using older technology.

  • With its massive surface area, Reticle CarbonŠ is amenable to solving the really difficult and sticky problems of removing toxic or pernicious ions in very, very dilute concentrations. One of today’s most difficult yet most important problems in that regard is to remove arsenic and other pernicious ions from prospective drinking waters. Present standards were recently reduced from 50 parts per billion to 10 ppb by the United States Environmental Protection Administration. (Such a standard is providing an economic burden on many industries.) Removal of dilute concentrations of ions is direct, simple, and economic using Reticle CarbonŠ in concert with CDI. Furthermore, if Reticle CarbonŠ can be shown to render concentrations as low as 10 parts per billion standard economically achievable, one would think that the EPA would immediately order it and rely on Reticle CarbonŠ to achieve it. Arsenic is known and agreed by all to be a difficult, cumulative problem even in trace quantities, just as are lead, selenium, and other toxic ions.

CDI technology requires a very large surface area, very conductive electrode material if it is to be successful and economic. Activated carbon is the most obvious choice as an electrode material—it has unprecedented surface area and because it is carbon-based, it is highly conductive. Attempts to make electrode materials from granulated activated carbon in the past have focused on binding activated carbon particles using polymers or clays or making the material from organic resins that are carburized and activated. No technique of this type has succeeded to date, and there are a number of insurmountable reasons: loss of surface area by occlusion, loss of mass by volatilization, loss of conductivity, and the prohibitive economics of the process. There has been a tremendous need for a more efficient, less expensive, more environmentally friendly process to manufacture activated carbon electrodes. Reticle has discovered and patented the secret.

Reticle CarbonŠ uses commercial grade granular activated carbon as a precursor to manufacture electrode material. Reticle CarbonŠ is manufactured using a process that preserves almost all the surface area of the precursor activated carbon after fabrication into monolithic solids (i.e., rigid blocks), uses no binder material, and contains no organic binders or additives. Reticle CarbonŠ is the ideal electrode material—it is ultra high surface area, monolithic structured, highly conductive, and chemically inert. The breakthrough represented by Reticle CarbonŠ relative to previous best in class high surface area electrodes lies in the surface area and conductivity of the Reticle CarbonŠ material (which incidentally is proprietary, confidential, patented, and owned by Reticle) and the fact that it can be machined into any shape, thickness, mass, etc. In particular, Reticle CarbonŠ can achieve over 2000 m2/g in monolithic electrodes, far higher than the 400 m2/g that is the current "best in class" in the industry. (The highest surface areas measured in commercial electrodes have been on the order of 400 m2/g. They have been measured for the Aerogel class of carbons. Aerogel carbons have simply not been suitable for brackish water or seawater desalination.) It is well to summarize the alternative approaches and to compare Reticle CarbonŠ with other alternatives.

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