| Autor: |
Rao U; Department of Civil and Environmental Engineering, University of California, Los Angeles, California 90095-153, United States., Iddya A; Department of Civil and Environmental Engineering, University of California, Los Angeles, California 90095-153, United States., Jung B; Department of Civil and Environmental Engineering, University of California, Los Angeles, California 90095-153, United States., Khor CM; Department of Civil and Environmental Engineering, University of California, Los Angeles, California 90095-153, United States., Hendren Z; RTI International, Research Triangle Park, North Carolina 27709, United States., Turchi C; Department of Energy, National Renewable Energy Lab, Golden, Colorado 80401, United States., Cath T; Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado 80401, United States., Hoek EMV; Department of Civil and Environmental Engineering, University of California, Los Angeles, California 90095-153, United States., Ramon GZ; Department of Civil and Environmental Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel., Jassby D; Department of Civil and Environmental Engineering, University of California, Los Angeles, California 90095-153, United States. |
| Abstrakt: |
The growth of mineral crystals on surfaces is a challenge across multiple industrial processes. Membrane-based desalination processes, in particular, are plagued by crystal growth (known as scaling), which restricts the flow of water through the membrane, can cause membrane wetting in membrane distillation, and can lead to the physical destruction of the membrane material. Scaling occurs when supersaturated conditions develop along the membrane surface due to the passage of water through the membrane, a process known as concentration polarization. To reduce scaling, concentration polarization is minimized by encouraging turbulent conditions and by reducing the amount of water recovered from the saline feed. In addition, antiscaling chemicals can be used to reduce the availability of cations. Here, we report on an energy-efficient electrophoretic mixing method capable of nearly eliminating CaSO 4 and silicate scaling on electrically conducting membrane distillation (ECMD) membranes. The ECMD membrane material is composed of a percolating layer of carbon nanotubes deposited on porous polypropylene support and cross-linked by poly(vinyl alcohol). The application of low alternating potentials (2 V pp,1Hz ) had a dramatic impact on scale formation, with the impact highly dependent on the frequency of the applied signal, and in the case of silicate, on the pH of the solution. |
