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Preparatory Chemistry and Other Topics
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Homegrown Oxidizers Part Thirteen WSM As we continued our cell preparations by filling the titanium tubes spot-welded to our electrodes, we encountered a major setback. The thin-wall titanium tubing was seriously compromised by the spot welding process and leaked out some of the lead-free solder through the spot welds as we were trying to fill them with the copper rods and solder. When things cooled down, we held the electrodes in our hands, and with very little force, could break them off t
Homegrown Oxidizers Part Twelve WSM Making Sodium Chlorate There are several advantages to making sodium chlorate over making potassium chlorate… and a few disadvantages. Potassium chlor-alkali salts are less and less soluble as their oxygen level raises. Sodium chlor-alkali salts, on the other hand, are more and more soluble as their oxygen level raises. What does this mean? When potassium chloride is converted to potassium chlorate in our cells, the chlorate, being less soluble than th
Homegrown Oxidizers Part Eleven WSM After drying and storing our homegrown potassium perchlorate, we need to test it for purity. This step could just as well have been done before drying our samples, but we wanted to do all our testing at the same time. The primary contaminant of concern is sodium. Sodium has very strong spectral lines (primarily yellow) that interfere with color production in pyrotechnics. In fact, the least amount of sodium will usually mask the weak violet spectrum of pot
Homegrown Oxidizers Part Ten WSM We’ve run two batches of sodium perchlorate, one with a platinum anode and the other with a lead dioxide anode. Now we have more than five liters of raw sodium perchlorate solution (contaminated with an unknown amount of residual sodium chlorate). The next step in producing potassium perchlorate involves the destruction of the chlorates in the cell solution. The treatment of choice is the gas, sulfur dioxide (SO2). Lacking the resources to buy and safely hand
Source: Pot. Chlorate by electrolysis?
Homegrown Oxidizers Part Nine WSM The Experimental Cells The lead dioxide cell with the anode sandwiched between two cathodes. On the left side of the photo above, a close fitting PVC assembly is shown which is used mainly to protect the Pyrex tank we used. It also added an insulating layer, which wasn’t our intention or particularly wanted. In the lid of the cell are four fittings: two for the electrodes, one for a Teflon coated thermal sensor and the last one to vent gasses generated
Homegrown Oxidizers Part Eight WSM As a proof-of-concept demonstration of the conversion of sodium chlorate to sodium perchlorate, we will set up some trial cells. Sodium chlorate is much more soluble than potassium chlorate, so our starting electrolyte concentration will be about 600 grams per liter of water (600g NaClO3/L H2O) or about 5 pounds per gallon. Higher concentration electrolytes are easier on the electrodes during the electrolysis process. To show proof of the presence of perchl
Homegrown Oxidizers Part Seven WSM The Holy Grail… Making Perchlorates We’ve primarily made potassium chlorate during our efforts so far. What about pushing forward and making, the more often used and useful, potassium perchlorate? Anodes and Other Differences from the Chlorate Process To make chlorates we used specific anodes which optimize the production of the ClO3- (chlorate) ion. Will those anodes also make perchlorates? Many have theorized they will but in practice this has not pro
Homegrown Oxidizers Part Six WSM The Continuous System in Practice The potassium chlorate batch systems previously discussed are simple compared to a continuous system. To run a chlorate system on a continuous basis involves a great deal of attention to myriad details (many of which can be ignored in batch systems), and to omit any one of them invites headaches and an inefficient system. Where, in batch systems it’s nice to track various conditions in the cell, in continuous systems, it’s
Homegrown Oxidizers, Part Five WSM Is that all there is? We’ve built and run single batch cells and even set them up to run fairly consistently. We’ve improved efficiency by controlling the pH to where we approach the “sweet spot” of ideal precursors to get more chlorate for the current consumed. But the big question is, “Can we run a system continuously the way industry does?” The short answer is, yes! The Continuous System Theory System Design Because of the complex steps and details
Homegrown Oxidizers Part Four WSM A fellow enthusiast has offered this method: When is a batch finished? For maximum anode life, one should end a batch run when the potassium chloride concentration drops to about 10% by weight. Without expensive analytical equipment the easiest way to infer the concentration is by measuring the specific gravity, which falls as the chloride is converted to the chlorate that largely drops out of solution. This can be done by carefully weighing a known volum
Homegrown Oxidizers Part Three WSM The Power Supply Our power supply (5Vdc, 30A) The name plate, showing the input and output power Since the power supply has a voltage adjust trimmer, we can adjust the output voltage slightly above or below the 5V rating. To save energy we adjust it downward as the cell needs less than 4 volts to operate. Since this supply has multiple positive and negative output terminals, combining the positive wires to the anode and likewise the negative wires to t
Homegrown Oxidizers Part Two WSM The Anode A key to modern chlorate production is the MMO anode. These were hard to come by many years ago, but now are so common that surplus material can be had at reasonable cost through careful searching. Part of the success of these MMO anodes is due to their large surface area (on a microscopic scale). The typical process of manufacture involves multiple coating and baking cycles that leave the microscopic surface looking like the cracked mud of a dry
Homegrown Oxidizers Part One WSM Not all of us live in an area friendly to fireworks. Access to these articles of celebration, let alone the materials to produce them may be extremely limited if not completely banned. Reliable information to produce fireworks raw materials is very difficult to find and even consulting professional chemists usually yields little useful information (unless they happen to work in the chlor-alkali industry). In these articles we’ll try to describe some workable
