Coatings continued chemical reduction

The reaction mixture is filtered. The soHds containing K MnO are leached, filtered, and the filtrate composition adjusted for electrolysis. The soHds are gangue. The Cams Chemical Co. electrolyzes a solution containing 120—150 g/L KOH and 50—60 g/L K MnO. The cells are bipolar (68). The anode side is monel and the cathode mild steel. The cathode consists of small protmsions from the bipolar unit. The base of the cathode is coated with a corrosion-resistant plastic such that the ratio of active cathode area to anode area is about 1 to 140. Cells operate at 1.2—1.4 kA. Anode and cathode current densities are about 85—100 A/m and 13—15 kA/m, respectively. The small cathode areas and large anode areas are used to minimize the reduction of permanganate at the cathode (69). Potassium permanganate is continuously crystallized from cell Hquors. The caustic mother Hquors are evaporated and returned to the cell feed preparation system. 

Despite extensive studies, the photovoltage or the solar-to-chemical energy conversion efficiency still remains relatively low. The main reason is that it is very difficult to meet all requirements for high efficiency. For example, high catalytic activity and sufficient passivation at the electrode surface are incompatible. It was found, however, that a semiconductor electrode modified with small metal particles can meet all the requirements and thus becomes an ideal type semiconductor electrode. Cu, Ag, and Au were chosen because they were reported to work as efficient electrocatalysts for the C02 reduction. p-Si electrodes modified with these metals in C02-staurated aqueous electrolyte under illumination produce mainly methane and ethylene.178 This is similar to the metal electrodes but the metal-particle-coated electrodes work at approximately 0.5 V more positive potentials, contrary to continuous metal-coated p-Si electrodes. 

Electroless deposition can be defined as a deposition of solid phase of continuous coatings (films) or powders of metals, alloys, or compounds from aqueous or nonaqueous solutions or melts without an external current source. Based on this definition, electroless deposition is a purely chemical process, which involves oxido-reduction... 

A final technique that has been utilized to chemically remove residual styrene in PS is radiation treatment. Both beta (e-beam) and gamma radiation have been tried. E-beam appears to be the most effective form of radiation and is most suitable for continuous use (319,320). The e-beam ruptures C—H bonds, resulting in the formation of PS radicals. These radicals are very reactive and scavenge unreacted monomer. However, if no styrene is in the vicinity of the PS radical, it can do other things such as couple with another PS radical or react with oxygen. Currently, electron beam treatment of polymers is used commercially for elastomer cross-linking (wire/cable coatings) but not for monomer reduction. 

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