Abstract: The invention relates to a process for production of hydrogen of high purity by photoelectrochemical means with low energy consumption.

Abstract: The device of the invention includes the following new elements in each mixer-settler: a) Agitators with blunt edged turbines, b) Decreasing degree of agitation throughout the series of mixing compartments, c) Baffle with a central window in the settler interface, located after the flow buffers, d) Baffle without a window, centred in the settler interface, located after the baffle with a window. These elements allow for an operative method which inhibits secondary dispersion, reducing the formation of micro-droplets, without affecting the mass transfer between the phases. Consequently, this obtains a phase separation process with entrainments so small that it is possible to drastically increase the quality of the product, by obtaining an ultra-pure aqueous extract, simultaneously reducing the settling surface required.