Towards a microscopic theory of electrostatic precipitation

The statistical mechanics of particles at the surface of a dust deposit are presented as a step towards a microscopic theory of electrostatic precipitation. The paper consists of three major divisions: (1) field induced entrainment, (2) particle condensation at the surface, and (3) hydrodynamic limits on precipitation.In the first part of this paper, the entrainment of dust from surfaces by electrostatic forces was considered as a simple Markov process. A choice of x⁻¹ for the dependence of the adhesive potential (van der Waals particle attraction) led to an exponential emission rate in the Kramers-Chandrasekhar approximation. This result suggested a simple experimental procedure for determining the adhesive properties of the dust. In addition it was found that both thermal Brownian and particle-deposit collisions contribute to the entrainment.In the second part, the precipitation problem was discussed in terms of a two-dimensional Ising model. The Markovian assumption demanded that the efficiency of the electrostatic precipitator be divided into a product of factors depending on particle migration and condensation in the two-dimensional surface. From this perspective a new collection criterion was established and the importance of particle collisions at the surface of the deposit was demonstrated.Finally, in the third part the role of bulk fluid flows in particle condensation and migration was addressed. The superficial gas flow and secondary flow were found to introduce anisotropy into the Ising lattice and also to enhance the mean particle energy at the surface. The Navier Stokes Equation was numerically integrated for the case of a wire-plate type corona. Plots of the stream function and gas velocity profile were presented and these suggested the existence of a lower limit on the shear stress that acts on surface particles.     

Plutonium concentration and 240Pu/239Pu atomic ratio in liver of squid collected in the coastal sea areas of Japan

Plutonium isotopes, 239Pu and 240Pu, were measured in liver samples from Surume squid using a sector-field high resolution ICP-MS after radiochemical purification. Surume squid samples were obtained from nine landing ports in Japanese inshore during fishery season from September to December 2002. Concentrations of 239Pu and 240Pu ranged from 1.5 to 28 mBq kg(-1) and 1.1 to 24 mBq kg(-1), respectively. Plutonium (239,240Pu) concentrations in liver were several thousand times higher than levels found in seawater. The concentration factor (CF) compared to seawater for 239,240Pu and 13 other elements ranged from 10(0) to 10(7). The CF values for 239,240Pu, V and Th were 10(2)-10(4). Pu had an intermediate CF between conservative and scavenged elements. 240Pu/239Pu atomic ratios in the squid liver ranged from 0.177 to 0.237 which were slightly higher than 0.178+/-0.014 for global fallout. The variations of 240Pu/239Pu atomic ratios in ocean currents with different source functions are important for interpreting high 240Pu/239Pu atomic ratios in Surume squid liver. It seems likely that Pu with high 240Pu/239Pu atomic ratio is continuously transported through the solubilization and seawater transport from the North Equatorial Current to Kuroshio and its branch, Tsushima Current. By assuming that Pu found in Surume squid liver is a mixture of global fallout Pu (0.178) and close-in fallout Pu with high 240Pu/239Pu atomic ratio (0.30-0.36) around Bikini Atoll, Pu contribution from Bikini close-in fallout Pu accounts for close to 35% of the whole plutonium in Surume squid liver. These results highlight that Surume squid is a useful organism for evaluating environmental Pu levels of larger sea area and facilitate the development of models to understand oceanic transport of close-in fallout Pu from Bikini Atoll.     

Japan’s greenhouse gas reduction scenarios toward net zero by 2050 in the material cycles and waste management sector

The first draft scenario toward net zero greenhouse gas (GHG) emissions by 2050 for the material cycles and waste management sector was presented by the Ministry of the Environment, Japan in August 2021. The details of the future GHG emission estimation used to create the draft scenario are described in this document. For multiple scenarios where more aggressive measures, such as carbon capture, utilization, and storage (CCUS), were included in addition to business-as-usual and the current policy continuity scenario, future GHG emissions were estimated as the sum of the products of activities and emission factors indicating changes in measures between scenarios. The estimation outcomes demonstrated that future GHG emissions from the solid waste management sector could be anticipated to be zero or even negative when material conversion to biomass, primarily for plastics, recycling to raw materials, and installation of CCUS at incineration facilities are assumed. Extensions of prior plans are not enough to reach the goal of net zero emissions, according to the measures necessary and the volume and pace of their implementation suggested in this study. Stakeholders should collaborate with great ambition.

     

Scenarios for reducing copper smelting-related atmospheric mercury emissions through copper recycling and mercury removal technologies in major countries

Journal of Material Cycles and Waste Management - Smelting of copper, a crucially important resource, releases small amounts of mercury into the atmosphere, thereby endangering people and the...