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Tritium extraction from radioactively contaminated cement mortar samples was performed using heating and liquid scintillation counting methods. Tritiated water molecules (HTO) can be present in contaminated water along with water molecules (H2O). Water is one of the primary constituents of cement mortar dough. Therefore, if tritium is present in cement mortar, the buildings and structures using this cement mortar would be contaminated by tritium. The radioactivity level of the materials in the environment exposed to tritium contamination should be determined for their disposal in accordance with the criteria of low-level radioactive waste disposal facility. For our experiments, the cement mortar samples were heated at different temperature conditions using a high-temperature combustion furnace, and the extracted tritium was collected into a 0.1 M nitric acid solution, which was then mixed with a liquid scintillator to be analyzed in a liquid scintillation counter (LSC). The tritium extraction rate from the cement mortar sample was calculated to be 90.91% and 98.54% corresponding to 9 h of heating at temperatures of 200 °C and 400 °C, respectively. The tritium extraction rate was close to 100% at 400 °C, although the bulk of cement mortar sample was contaminated by tritium.

Developing an online monitoring system becomes useful for continuously detection of tritium in water. A plastic scintillator chamber was used to tritium detection in hydrogen gas produced by a proton exchange membrane electrolysis cell. The fractionation factor (proton selectivity) was estimated as being of 5.41 ± 0.20, and detection efficiency of the plastic scintillator chamber was 4.25 ± 0.22%. For liquid samples, the minimum detectable activity of the developed system was estimated as 655 kBq L−1. Using this online technique for tritium monitoring based on electrolysis is expected to be useful for analysis of large tritiated water bearing samples.

During dividing wall column (DWC) operation, the liquid and vapor split ratios must be actively tuned to maximize the energy-saving potential for the desired separation process. However, no active vapor split control devices have been reported to be installed in existing industrial DWCs. Therefore, the enhanced active vapor distributor (EAVD®) has been developed to overcome the existing problems in controlling the vapor split ratio in DWCs. In the EAVD, the opening area for the vapor flow is tuned by altering the liquid level of a modified chimney tray. The liquid level can be adjusted by operating the control valve in each section of the DWC. In this study, a laboratory-scale EAVD was tested under a number of experimental conditions to validate its reliability for controlling the vapor flow associated with its pressure drop behavior in a DWC. The results showed that the use of an EAVD allowed the pressure drop differences in the above mass transfer section to be compensated, and the desired vapor split ratio could be achieved during operation. Furthermore, modification of the existing DWCs can be easily accomplished by substituting the current chimney tray with the EAVD, improving the operability and flexibility of DWCs.

A novel active vapor distributor (AVD) was proposed to address the need for vapor split control during dividing wall column (DWC) design and operation. A DWC’s energy efficiency can be significantly reduced by a small deviation in the vapor split ratio; therefore, the vapor split ratio needs to be regulated during operation. In the proposed AVD, vapor splitting was implemented by a modified chimney tray with a specially designed cap. The liquid level of the chimney tray on each end side of the dividing wall section could be adjusted to control the vapor flow split. As the proposed AVD adjusts the friction of the vapor flow path efficiently without any mechanical moving parts, it can realize a more reliable operation of a DWC. The performance of the proposed AVD was evaluated, and the results demonstrated its easy implementation and superior ability to regulate vapor flow split during DWC operation.

An extraction and distillation hybrid process using a novel mixed solvent was proposed for enhancing acetic acid recovery during terephthalic acid production. Feasible hybrid extraction–distillation schemes were designed, simulated, and optimized for two mixed solvents, p-xylene + methyl acetate, and p-xylene + ethyl acetate, based on liquid–liquid equilibrium data for a quaternary system containing methyl acetate or ethyl acetate with p-xylene, acetic acid, and water. A hybrid process using the p-xylene + methyl acetate mixed solvent was found to generate the desired purity of acetic acid with a lower energy consumption and higher product yield than conventional extraction processes. Results showed that the proposed hybrid extraction–distillation process improves the process economics remarkably: the hybrid process using the p-xylene + methyl acetate and p-xylene + ethyl acetate mixed solvent reduced a total annual cost by 14% and 6%, respectively, compared with the conventional hybrid process using the ...

Square-shaped absorption towers are compact and provide high volumetric efficiency, enabling the installation of closed-loop flue gas desulfurization (FGD) in limited spaces of a ship. For FGD processes, diluted sodium hydroxide (NaOH) has been considered as a viable absorbent. Thus, a square-shaped scrubber with square spray nozzle distributor using a diluted NaOH solution was proposed for marine sulfur oxides removal, aiming to reduce volume/space, weight, pressure drop, investment, and operating and maintenance costs while increasing efficiency. A systematic methodology for the square-shaped FGD design was proposed, experiments to treat the flue gas released from a marine diesel engine (720 kW) were performed, and simulation and sensitivity analyses were conducted using Aspen Plus V10. Good agreement was observed between experimental and simulated results. A liquid-to-gas mass ratio of approximately 4.32 kg.kg−1 provided SO2 removal efficiency higher than 95 %. Most part of mass and heat transfers occurred in the bottom section of the scrubber and a low pressure drop was achieved.

The experimental liquid–liquid equilibrium (LLE) data of the quaternary (acetic acid + water + p-xylene + methyl acetate) system was investigated at 313.2 K and atmospheric pressure. This research is aimed to examine the potential of the mixture of methyl acetate and p-xylene, which available as the remaining substances in terephthalic acid production, to be prospective extracting solvent for the acetic acid dehydration. LLE phase diagrams at different ratio of p-xylene to methyl acetate were presented for this quaternary system. The results showed that an enlargement of the LLE two-phase region occurred with increasing p-xylene to methyl acetate mass ratio in the initial solvent phase. The distribution coefficient and selectivity for the extraction of acetic acid were also obtained to evaluate the capability of solvent. LLE data were sufficiently correlated by Othmer-Tobias and Bachman equations. The experimental results were used to obtain binary interaction parameters as correlated by the non-random two liquid (NRTL) and universal quasi-chemical theory (UNIQUAC) equation models. The root mean square deviations (RMSD) values as low as 0.0119 and 0.0128 were calculated for NRTL and UNIQUAC, respectively; indicating excellent results for both models were suitable for the determination of LLE data of this quaternary system.

The liquid–liquid equilibria (LLE) data for the quaternary system, acetic acid, water, p-xylene, and ethyl acetate, was obtained at 313.15 K under atmospheric pressure. The composition distribution of each component on the aqueous phase and organic phase were investigated. To examine the effects of the solvent, the LLE phase diagrams at different p-xylene to ethyl acetate ratios are presented for this quaternary system. The reliability of the tie-line data of this study was also confirmed using the Othmer–Tobias and Hand equation. The distribution ratio and separation factors for the extraction of acetic acid from the aqueous solutions were obtained. Furthermore, the equilibrium data of this study was analyzed using the quasichemical activity coefficient (UNIQUAC) and nonrandom two liquid (NRTL) models. The experimental data was correlated successfully with both the activity coefficient models that were extended with each binary interaction parameter. To determine the accuracy of each activity model, the ...