RESUMO
This paper presents a fully-continuous novel liquid-liquid-extraction (LLE) platform for the purification of nanoparticles. The use of multistage operation enhances the purity of the final stream without the expense of high solvent consumption. Two case studies, purification of CdSe quantum dots in organic solvent and that of gold nanoparticles in water, demonstrate that the LLE platform is versatile, non-destructive, and highly efficient.
RESUMO
A technical analysis has been completed for a commercial-scale two-stage gasification-combustion system. The CLEERGAS (Covanta Low Emissions Energy Recovery GASification) process consists of partial combustion and gasification of as-received municipal solid waste (MSW) on a moving grate producing syngas followed by full combustion of the generated syngas in an adjoining chamber and boiler. This process has been in operation since 2009 on a modified 330-tonne day(-1) waste-to-energy (WTE) line in Tulsa, Oklahoma. Material balances determined that the syngas composition is 12.8% H2 and 11.4% CO, the heating value of the gas in the gasifier section is 4098 kJ Nm(-3), and an aggregate molecular formula for the waste is C6H14.5O5. The analysis of gas measurements sampled from the Tulsa unit showed that the gasification-combustion mode fully processed the MSW at an excess air input of only 20% as compared to the 80-100% typically found in conventional WTE moving grate plants. Other important attributes of the CLEERGAS gasification-combustion process are that it has operated on a commercial scale for a period of over two years with 93% availability and utilizes a moving grate technology that is currently used in hundreds of WTE plants around the world.