Chloride. High temperature causes the desiccation of the bentonite block and induces the precipitation of salts at the interface (chlorides and carbonates mainly). Salt precipitation may play a relevant role in the performance of the carbon steel canister in the repository. Chloride precipitates are well-known for being hygroscopic. This fact could lead to the formation of very concentrated brines on the surface of the canister, what could favour localized corrosion. The most relevant transport processes occurring in the cell may be deduced from the behaviour of chloride. The Cl- distribution is closely related to the water advection, with the formation of saline fronts moving towards the heat focus. Chloride is easily dissolved when less saline water enters the column and is transported as the hydration front moves to the unsaturated areas, as previously Xxxxxx et al. [35]. The advance of Cl- depends on the duration of the experiment. In the FB1 (174 days) experiment, the maximum chloride content was localized in the intermediate zone. As the hydration front advanced, as in FB2 (480 days), chloride was concentrated at the heating zone and the interface (hottest zone). According to the chemical analysis made on FB3 (1593 days), still unsaturated, Cl- concentration is also higher at the interface. Data obtained from the chemical analysis indicate that advection prevails over diffusion as mechanism for salt movement (Figure 7). Bentonite block mmol Cl/100g dry bentonite 12 6 months 15 months 10 54 months Fe powder 6 4 2 0 10 20 30 40 50 60 70 80 Distance from hydration (mm) 90 100 Figure 7. Distribution of soluble chloride found in the three medium- cell tests dismantled. The increase of salinity in the hottest parts of bentonite is possibly caused by the formation of small convection cells generated due to the thermal gradient. At the iron/bentonite interface, water absorbed in bentonite evaporates and moves towards the coldest areas, where it condensates. Liquid water moves again towards the heater. During this movement, the most soluble minerals are dissolved. The hydration front transports salts and saline fronts are generated along the bentonite block. The mobility of these fronts depends on each element. Xxxxxx et al. [36] however, proposed that the driving force for salt transport would be the increase of salt concentration on the mesopore “external” water with respect to the “surface-influenced” (anion exclusion) micropore water. The preservation of primitive ...
Chloride. Perchloric Acid, 70%, Redistilled, 99.99% Phosphoric Acid Platium (II) 2,4-pentanedionate Platinum 20%, Ruthenium 10% on carbon black Platinum Wire (Metal) Platinum Foil (Metal) Platinum, 40% on carbon black RI1980 Polyimide Developer PI2721 Polyimide Coating Potassium Hydrogenphosphate, 98+%, A.C.S. Reagen Potassium Hydroxide, 45 wt.. % solution in Water Potassium Hydroxide, Pellets, 85+%, A.C.S Reagent Potassium Nitrate Potassium Phosphate, 97% PSE-300 Pur-A-Gold - Base Adjusting Salt Pur-A-Gold - 401 Make Up Pur-A-Gold - Replenisher A Pur-A-Gold - Replenisher B Pur-A-Gold - Thallium Additive Pyrazine Pyrocatechol Silicone Elastomer Sodium Hydroxide Sulfur Hexaflouride (SF6 - compressed gas) Sulfuric Acid Ruthenium (III) Chloride Hydrate Ruthenium (III) nitrosylnitrate Ruthenium (Ill) 2,4-pentanedionate Tantalum Foil (Metal) TechFilm T2321
Chloride. Concentrations of chloride in the influent AMD drainage were relatively consistent with values averaging 14 mg/L Cl- during the course of the experiment. 3000 Dissolved Chloride (mg/L Cl-) 2500 2000 1500 1000 500 0 Influent Reactor 1 (LS) Reactor 2 (10:90) Reactor 3 (30:70) Reactor 4 (50:50) Reactor 5 (70:30) Reactor 6 (90:10) Sampling Date Figure 25 Measured chloride concentrations (mg/L Cl-) of the AMD influent and the effluent of each reactor (R1-R6) for each sampling event. 40 Dissolved Chloride (mg/L Cl-) 35 30 Influent Reactor 1 (LS) 25 Reactor 2 (10:90) 20 Reactor 3 (30:70) 15 Reactor 4 (50:50) Reactor 5 (70:30) 10 Reactor 6 (90:10) 5 0 Sampling Date Figure 26 Expanded view of the measured chloride concentrations (mg/L Cl-) of the AMD influent and effluent of each reactor (R1-R6) for each sampling event. Aside from a few spikes in chloride concentrations, the limestone reactor exhibited similar values with respect to the AMD influent (Figure 25). Still, due to the high concentrations of these documented peaks in chloride the limestone only reactor (R1) average 37mg/L chloride over the course of the experiment. Chloride concentrations within the bioreactors (R2-R6) can be separated in three events high concentration, medium concentrations and concentrations near influent AMD. During the first two months average chloride concentrations ranged from 730-1675 mg/L Cl- with maximum values over 2500 mg/L Cl-. Subsequent declines in chloride values occurred during the following four months (November 2012- February 2012) and average concentrations ranged between 42-90 mg/L Cl-. Lastly, during the final six months of the experiment chloride values measured in the samples taken for the effluent of each bioreactor (R2-R6) fell below the average AMD influent values with average concentrations ranging from 9.4-11.5mg/L Cl- (Figure 26).
Chloride. Based on expert consultations conducted by Health Quality Ontario, chloride testing in the community setting has limited utility. Therefore, OHTAC recommended that chloride testing in the community should be reduced by removing chloride from the Ontario laboratory requisition form.
