Extra-virgin cold-pressed tunafish (no mercury)
I've given some more thought to the idea of removing mercury from seafood via centrifuge-assisted gravity. The method is commonly used for settling large particles out of solutions, but it slows down drastically as particle size decreases.
The standard Stoke's equation for the velocity of a falling particle in a fluid is:
Velocity = 2 * particle radius^2 * (Particle density - fluid density) * gravitational acceleration / (9 * liquid viscosity)
Effective particle radius for a mercury ion in an aqueous solution is complicated. If you add in wacky organics and biological compounds it gets much too complicated for me to figure out. I'll therefore guess at a rough best-case scenario, with a particle radius of ~0.5 nanometer (about 4 mercury atoms), and a density of 2g/cm^3
viscosity of water = 0.01 kg / m * s
Velocity = 2 * (0.25 * 10^-18 m^2) * (2000 - 1000 kg/m^3) * 9.8 m/s^2 / (9 * 0.01 kg / m*s) =
0.5 * 10^-18 * 10^3 * 10^1 / 10^-1 m/s = 0.5 * 10^-13 m/s, or 0.2 nanometers per hour. At that rate, it would take seven hundred years to clean a layer of tunafish a millimeter thick at 1 gravity. Given a laboratory ultracentrifuge running at 1 million G*, you could do it in six hours. So it's vaguely plausible.
But I really don't know if my estimates for particle radius and density are accurate. I could be optimistic by a factor of 10, or pessimistic by a factor of 2. And I'm not absolutely sure Stoke's equation applies at such a small scale. I may have to wait on this one until I find someone who knows more biochemistry and chemical engineering than I. Hey Vy:)
*Admittedly not good for the health of any Russian ex-spies you're trying to decontaminate.
Update: Discussions have brought up a critical flaw: The seafood would be squashed strained* into goo by the centrifugal forces required to segregate out the mercury in reasonable time.
*see comment discussing density-difference float/sink stresses under high gravitational field(worrisome), and high uniform hydrostatic pressure (should be ok for some, maybe all fish).
Although large, fatty, predatory fish have higher mercury concentrations overall, I'm not sure whether mercury accumulates specifically in fatty tissue. This source suggests it doesn't, and that cooking and cleaning methods don't make much of a difference for mercury. But this source suggests that it does accumulate specifically in fat, and that removing fat during cooking will help. Argh.
Everybody seems to agree that dioxins and PCBs do accumulate specifically in fish fat. On the other hand, all that fish fat, omega-3 oil, etc is supposed to be good for you.
subjectivity found this page on the mercury-blocking benefits of selenium (also found in fish). I wonder if making cookpots with a small percentage of selenium in the alloy would help as well?
The standard Stoke's equation for the velocity of a falling particle in a fluid is:
Velocity = 2 * particle radius^2 * (Particle density - fluid density) * gravitational acceleration / (9 * liquid viscosity)
Effective particle radius for a mercury ion in an aqueous solution is complicated. If you add in wacky organics and biological compounds it gets much too complicated for me to figure out. I'll therefore guess at a rough best-case scenario, with a particle radius of ~0.5 nanometer (about 4 mercury atoms), and a density of 2g/cm^3
viscosity of water = 0.01 kg / m * s
Velocity = 2 * (0.25 * 10^-18 m^2) * (2000 - 1000 kg/m^3) * 9.8 m/s^2 / (9 * 0.01 kg / m*s) =
0.5 * 10^-18 * 10^3 * 10^1 / 10^-1 m/s = 0.5 * 10^-13 m/s, or 0.2 nanometers per hour. At that rate, it would take seven hundred years to clean a layer of tunafish a millimeter thick at 1 gravity. Given a laboratory ultracentrifuge running at 1 million G*, you could do it in six hours. So it's vaguely plausible.
But I really don't know if my estimates for particle radius and density are accurate. I could be optimistic by a factor of 10, or pessimistic by a factor of 2. And I'm not absolutely sure Stoke's equation applies at such a small scale. I may have to wait on this one until I find someone who knows more biochemistry and chemical engineering than I. Hey Vy:)
*Admittedly not good for the health of any Russian ex-spies you're trying to decontaminate.
Update: Discussions have brought up a critical flaw: The seafood would be squashed strained* into goo by the centrifugal forces required to segregate out the mercury in reasonable time.
*see comment discussing density-difference float/sink stresses under high gravitational field(worrisome), and high uniform hydrostatic pressure (should be ok for some, maybe all fish).
Although large, fatty, predatory fish have higher mercury concentrations overall, I'm not sure whether mercury accumulates specifically in fatty tissue. This source suggests it doesn't, and that cooking and cleaning methods don't make much of a difference for mercury. But this source suggests that it does accumulate specifically in fat, and that removing fat during cooking will help. Argh.
Everybody seems to agree that dioxins and PCBs do accumulate specifically in fish fat. On the other hand, all that fish fat, omega-3 oil, etc is supposed to be good for you.
subjectivity found this page on the mercury-blocking benefits of selenium (also found in fish). I wonder if making cookpots with a small percentage of selenium in the alloy would help as well?