Two-cycle processes

PoUowing further development (38), a two-cycle process has been adopted by industry. In the first concentration cycle, the clarified feed acid containing 100—200 mg/L U Og [1334-59-8] is oxidized, for example, with hydrogen peroxide or sodium chlorate [7775-09-9] to ensure that uranium is in its 6+ valence state is not extracted. Uranium is extracted with a solvent composed of 0.5 Af D2EHPA and 0.125 Af TOPO dissolved in an aUphatic hydrocarbon diluent. 

Two-cycle processes, which achieve the An(III)/Ln(III) separation only after a first cycle of An(III) + Ln(III) coextraction and separation from the rest of the fission products... 

Historically, pairs of processes have been developed throughout the world to achieve An(III)/Ln(III) partitioning TRUEX + TALSPEAK in the United States, TRPO + CYANEX in China, DIDPA + DIDPA in Japan, and DIAMEX + BTP or DIAMEX + ALINA in Europe, but cross combinations of processes are possible. The one-cycle processes (e.g., SETFICS and DIAMEX-SANEX/HDEHP) appear more attractive and more compact than the two-cycle processes, as they do not use two different solvent loops to carry out the separation of An(III) from Ln(III), but they sometimes generate much larger aqueous streams than the feed input. 

Facchini, A., Amato, L., Nannicini, R. 1996. A two-cycle process for enhanced actinide separation from radioactive liquid wastes. Separation Science and Technology 31(16) 2245-2256. 

Di (tridecyl) amine can also be used for the extraction of thorium from the very dilute liquor left after either ion-exchange or solvent extraction of Blind River ores. For example, in a two cycle process, tri-iso-octylamine first extracts the uranium and the di (tridecyl) amine cycle is then adjusted to remove the thorium with the minimum iron contamination. The thorium is backwashed with 1M sodium chloride-0 05M sulphuric acid solution and precipitated with ammonia. 

It follows that the efficiency of the Carnot engine is entirely determined by the temperatures of the two isothermal processes. The Otto cycle, being a real process, does not have ideal isothermal or adiabatic expansion and contraction of the gas phase due to the finite thermal losses of the combustion chamber and resistance to the movement of the piston, and because the product gases are not at tlrermodynamic equilibrium. Furthermore the heat of combustion is mainly evolved during a short time, after the gas has been compressed by the piston. This gives rise to an additional increase in temperature which is not accompanied by a large change in volume due to the constraint applied by tire piston. The efficiency, QE, expressed as a function of the compression ratio (r) can only be assumed therefore to be an approximation to the ideal gas Carnot cycle. 

The Brayton cycle in its ideal form consists of two isobaric processes and two isentropic processes. The two isobaric processes consist of the combustor system of the gas turbine and the gas side of the HRSG. The two isentropic processes represent the compression (Compressor) and the expansion (Turbine Expander) processes in the gas turbine. Figure 2-1 shows the Ideal Brayton Cycle. 

Many opportunities conversely are supported by reversible reactions of QM despite the noted complications. One example includes the synthesis and chiral resolution of binaphthol derivatives by two cycles of QM formation and alkylation.77 The reversibility of QM reaction may also be integrated in future design of self-assembling systems to provide covalent strength to the ultimate thermodynamic product. To date, QMs have already demonstrated great success in supporting the opposite process, spontaneous disassembly of dendrimers (Chapter 5). 

Photosynthesis in green plants occurs in two basic processes. In the dark (the Calvin cycle) carbon dioxide is reduced by a strong reducing agent, the reduced form of nicotinamide adeninedinucleotide phosphate, NADPH2, with the help of energy obtained from the conversion of ATP to ADP ... 

Choosing the most stable TiO modification. It has been shown that chalking is the result of two main processes UV degradation and the photocatalytic oxidation cycle. What can be done to stabilize Ti02 pigments in such a way that they cause as little chalking as possible A few possibilities have already been mentioned ... 

According to Cairns-Smith, the first primitive gene materials could have been clay minerals these crystallize out everywhere on Earth from dilute silica solutions and hydrated solutions of metal ions. Both groups of substances are continually being formed by weathering processes. Two cycles keep this dynamic process going ... 

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