A high school friend once related the story about how his father, a chemist for an environmental waste concern, disposed of a problematic quantity of metallic sodium by dumping it into one of the more polluted rivers in southern New England. Despite the fact that the local residents were used to seeing all manner of noxious hijinx in the river, the resulting explosion was supposedly enough to warrant a call to the police and an expeditious retreat back to the labs. It was a good story, but not especially believable back in the day.
After seeing this video of how the War Department dealt with surplus sodium in 1947, I’m not so sure. I had always known how reactive sodium is, ever since demonstrations in chemistry class where a flake of the soft gray metal would dance about in a petri dish full of water and eventually light up for a few exciting seconds. The way the US government decided to dispose of 20 tons of sodium was another thing altogether. The metal was surplus war production, probably used in incendiary bombs and in the production of aluminum for airplanes. No longer willing to stockpile it, the government tried to interest industry in the metal, but to no avail due to the hazard and expense of shipping the stuff. Sadly (and as was often the case in those days), they just decided to dump it.
Continue reading “Retrotechtacular: Disposing Of Sodium, 1947-Style”
Some people collect stamps, some collect coins, some even collect barbed wire. But the aptly named [Plutonium Bunny] is an element collector, as in one who seeks a sample of as many elements on the periodic table as possible. Whatever, we don’t judge – after all, there are more than a few Hackaday readers who collect lots of silicon, right?
So what’s a collector to do when he gets to the 25th place on the periodic table? Easy – harvest manganese from alkaline batteries with a thermite reaction. There’s a surprising amount of manganese in depleted alkaline batteries, which of course are easy to come by in bulk. The chemistry of [Plutonium Bunny]’s process is pretty straightforward and easy to reproduce with common ingredients, but you’ll want to be careful with a few steps – chlorine gas is not something to trifle with. The basic idea is to solubilize and purify the manganese dioxide from the other materials in the battery cathodes, recrystallize it, and mix it with aluminum powder. The aluminum acts as the fuel, the manganese dioxide is the oxidizer, and once the satisfyingly exothermic reaction shown in the video below is over, the collector-grade elemental manganese can be chipped away from the aluminum oxide slag.
So once you’ve got a few manganese nuggets, what can you do with them? Not much really – it turns out the oxides recovered from the battery are far more useful for things like supercapacitors. But it’s still a neat trick.
Continue reading “Old Batteries Yield Thermite And Manganese”
It says it right on the side of every alkaline battery – do not attempt to recharge. By which of course the manufacturer means don’t try to force electrons back into the cell. But [Cody] figured he could work around that safety warning chemically, by replacing the guts of an alkaline dry cell.
The batteries in question were certainly old, gnarly looking, and pretty dead – [Cody] barely got a reading on his multimeter. As you can see after the break, he cleaned off the exterior corrosion and did a quick teardown of the dry cells, removing the remains of the zinc anode, now in the form of zinc oxide paste looking very much like what you’d slather on your nose before a day at the beach. He filled the resulting cavity with a putty of zinc dust, freshened up the electrolyte charge with a squirt of 20% potassium hydroxide, sealed up the cell with a little silicone caulking, and put the recycled cell to the test. Result: 1.27 volts. Not too shabby.
Continue reading “One Way To Recharge Alkaline Batteries”
Batteries come packaged in bright blister packs emblazoned with vague guarantees such as “45% more pictures” and “five times longer lasting.” During his internship at BitBox this summer, [Thomas] decided to put those statements to the test. He tested thirty brands of batteries on a homebrew rig to find the batteries with the most power and the most bang for your buck.
The hardware [Thomas] used an STM32 microcontroller to perform two different tests: a high drain and a low drain condition. For the high drain, 1000 mA were sucked out of the batteries until the voltage reached 0.8 V. For the low drain, 200 mA were used. Data including milliwatt-hours, milliamp-hours, joules, voltage, current, power, and effective load resistance were all logged for both conditions for all 30 batteries.
Generalizing the results for both low and high drain conditions, lithium batteries were better than alkaline, which were both better than zinc AA cells. Perhaps unsurprisingly, batteries marketed as ‘long life’ and ‘extended power’ were the worst batteries for the money, but a brand-name battery – the Kodak Xtralife cells – were actually the best value for the money.