Tribo-electrostatic separation of binary mixtures from polymeric and food materials

Tribo-electrostatic separation in a free-fall separator with a set of prepared mixtures from seven powder materials was investigated, five of them being polymers, whilst the other two are commonly used powders of food origin (cellulose, PTFE, barley starch, whey protein, high-density polyethylene, polyethylene and polyamide). Quantification of material content on the separated fractions attached to the electrodes led to deduce a triboelectric series, where materials are ranked in a sequential mode according to their charging behavior. The obtained material proportion in the separated fractions partially reproduces the idea that, the farther apart two materials are located in the triboelectric series, the larger the difference between their relative proportions on each electrode. The experimental work is supplemented with an estimation of the relative strength of forces acting on the charged particles as they move to the electrodes.