Why does 2-(2-aminoethylamino)ethanol have superior CO2 separation performance to monoethanolamine? A computational study.

Our computational reaction analysis shows that 2-(2-aminoethylamino)ethanol (AEEA) has superior performance to monoethanolamine for CO2 separation, in terms of its ability to sorb CO2 by its primary amine and desorb CO2 by its secondary amine.

Acceleration of rises in the level of rivers induced by rising air temperatures in a cold climate.

The effects of climate change on water discharge in rivers in cold climates were investigated. To quantify the impacts of air temperature rises on the promotion of snowmelt and associated acceleration of a rise in the level of a river, 10 rivers on Hokkaido, northwestern Japan were chosen. Available data of daily water discharge for more than half a century by the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) were correlated with air temperatures observed at the 8 weather stations operated by the Japan Meteorological Agency (JMA). The analyses show that annual average air temperatures have risen at all 8 sites on Hokkaido for the period from 1954 to 2018. The trends for the 8 sites show a range from 0.119 °C/decade to 0.250 °C/decade with an average of 0.191 °C/decade. Annual snowfall has increased at Sutsu. The trend over the period from 1954 to 2018 was 45.2 cm/decade. Otherwise, annual snowfall has not changed significantly in the period (1954-2018). Accelerations of the rise in the level of the river induced by air temperature rises have been observed in the Teshio River, Ishikari River, Saru River, and Mu River. A delay in the rise in the level of the river caused by an increase in snowfall and the weak warming trend from January to April has been observed in the Shiribetsu River. Although air temperatures have risen year after year, a significant change in annual pattern of daily flow has not been observed in the Syokotsu River, Yubetsu River, Tokoro River, and Abashiri River located in eastern Hokkaido. This can be induced by the weak warming trends in April which may be due to the cold current of the sea of Okhotok.

Effects of clay in a sandy soil on saturated/unsaturated pore water flow and dissolved chloride transport from road salt applications.

Saturated/unsaturated pore water flow induced by rainwater infiltration in a soil column composed of a mixture of Toyoura sand and a small amount of clay (kaolin minerals) and the rinsing rate (mass transfer) of dissolved NaCl accumulated in the pore system from previous road salt application were investigated by experiments and simulations. Experiments were conducted with variable kaolin minerals mass contents (mixing ratios) in the soil columns. Measured saturated hydraulic conductivity (Ks) diminished with increased clay contents, i.e., Ks=0.00771, 0.00560, 0.00536, 0.00519, and 0.00314 cm s-1, for clay contents = 0.2, 0.5, 1, 2, and 5%, respectively. Experimental NaCl concentrations in the effluent from the bottom of the soil columns were about constant for times t ≈ 800, 1200, 1300, 1400, and 3400 s from the beginning of a rinsing experiment for the clay contents = 0.2, 0.5, 1, 2, and 5%, respectively. These NaCl concentrations then decreased with time quickly, and finally, approached zero. The presented model can reproduce experimental time variations of NaCl concentration in the effluent from the soil column reliably. Simulated salt mass left in the soil column with time also matches the experimental results for the clay contents = 0.2 and 0.5%. An inconsistency between simulated and experimental salt mass left in the soil columns becomes more significant as the clay content increases. These results suggest that the soil-water retention curve for the pure Toyoura sand can be applied to the soil column composed of kaolin minerals/Toyoura sand mixture when the clay content is small, i.e., less than 1%. Prediction of rinsing process becomes more difficult with increased clay content. However, the time required to remove saline water from the soil column to less than 1% of its initial value simulated by the model agrees closely with experimental results of 1000, 1500, 1700, 2100, and 5400 s, respectively.