A cylindrical reactor with a swirling flow is tested for the production of colloidal sulphur via the oxidation of sulphide ions with a concentration of 2 g dm⁻³ in alkaline solutions at 80 °C. Polysulphides are anodically formed at the outer electrode, coated with lead, whereas hydrogen evolution takes place in the internal electrode as the main cathodic reaction. This geometrical arrangement enables the application of an undivided reactor working with a high current efficiency. Polysulphide's formation occurs over a wide span of potential, from 0 to 1 V against a saturated calomel electrode, at a constant current density that is scarcely dependent on the hydrodynamics. The tests were carried out under potentiostatic control (0.6 V) and colloidal sulphur was obtained by acidification of the final solution. For a 9.6 dm³ min⁻¹ volume flow rate, the space time yield and the specific energy consumption were 29.3 kg m⁻³ h⁻¹ and 27.3 kW h kg⁻¹, respectively, with the current efficiency being close to 100%. Trials under a two-phase flow corroborate the appropriate reactor performance. The colloidal sulphur particles are of high purity, present different shapes and have micrometric dimensions with average sizes ranging from 1.4 to 4.2 μm.

中文翻译：

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旋流反应器中硫化物电化学氧化生产胶体硫

测试了具有旋流的圆柱形反应器通过氧化浓度为 2 g dm ^-3的硫化物离子来生产胶体硫在 80 °C 的碱性溶液中。多硫化物在外电极处阳极形成，涂有铅，而氢析出发生在内电极中，作为主要的阴极反应。这种几何排列能够应用以高电流效率工作的未分隔的电抗器。多硫化物的形成发生在很宽的电位跨度上，从 0 到 1 V，相对于饱和甘汞电极，在几乎不依赖于流体动力学的恒定电流密度下。测试在恒电位控制 (0.6 V) 下进行，胶体硫通过最终溶液的酸化获得。对于 9.6 dm ³ min ^-1体积流量，时空产率和比能量消耗为 29.3 kg m ^-3h ^-1和 27.3 kW h kg ^-1，电流效率接近 100%。在两相流下的试验证实了适当的反应器性能。胶体硫颗粒纯度高，呈现不同的形状，具有微米级尺寸，平均尺寸为 1.4 至 4.2 μm。