The role of particle size on the deposition efficiency of ink on plastic spheres

Experimental investigation of the effect of carbon particle size on its deposition efficiency on the surface of plastic particles has been performed in stirred vessel. A model based on Langmuir kinetics was used, and it provided a good fit for the experimental results. The effect of de-inking conditions such as, carbon particle size, calcium chloride concentration, and carbon concentration has been investigated. Different sizes of carbon particles were tested. It was found that the deposition rate and the deposition efficiency were generally higher for the larger carbon particles. The effect of CaCl ₂ concentration on the deposition efficiency was investigated. Results showed that the deposition rate increased when the concentration of CaCl₂ increased from 0.05 to 0.10g/l (the stochiometric ratio needed to react with sodium stearate). Moreover, the deposition efficiency was higher at this concentration. Concentrations above the stochiometric ratio did not show a systematic behavior for the deposition rate and the deposition efficiency. Finally, the effect of carbon concentration was examined. Carbon concentration of 0.25, 0.30, and 0.40g/l were used. Results showed that the concentration of carbon did not affect the deposition efficiency nor the rate of deposition. This study confirmed the applicability of the method of ink removal from recycled waste paper using plastic particles, proposed by previous investigators.