Separation of hydrophilic inks such as pigmented inkjet and flexographic inks has been an issue in paper recycling since the beginning of their use. The use of inkjet printing is continuing to increase, and it does not appear that this increase will stop anytime soon. Because of this, it is essential to find an adequate method of deinking these inks for the recycling of paper products. There has been a significant amount of research on methods of improving deinking of these inks, but none have been effective up to this point. Additionally, there has been a significant amount of research studying the effects of deinking parameters on these inks, but there are still gaps in this knowledge. A thorough investigation of deinking chemicals and parameters was conducted in this research along with an investigation of the behavior of the hydrophilic inks during the paper recycling, such as the detachment and reattachment of the ink. Through this analysis, two novel deinking methods were developed to decrease the redeposition and improve the separation of these inks. These methods were adsorption deinking and Liquid Phase Plasma (LPP) treatment. Both of these methods were shown to improve the deinkability of hydrophilic inks. However, LPP treatment was also seen to have a negative impact when hydrophilic inks were mixed with traditional hydrophobic inks. It was hypothesized and shown that LPP treatment has a positive impact on deinking of hydrophilic inks but a negative impact on traditional inks, which led to the development of the adsorption deinking method that can deink both hydrophilic and traditional inks.

This thesis presents an experimental study of non-thermal atmospheric pressure gas plasmas in presence of liquid as an efficient source of transient and reactive species to initiate chemical reactions necessary for many important applications. Two types of liquid-containing plasmas are considered: discharges formed between a needle electrode and a liquid electrode, and plasma jets formed in a water vapour flow mixed in helium or argon gas. Two plasma modes (the pulsed and the continuous mode) are observed in the needle-to-liquid plasma. A comparative study of the needle-to-liquid plasma in the continuous mode with DC and AC excitations reveals that the plasmas are glow discharges, and AC excited plasmas have the highest energy efficiency. A study of helium/water vapour plasma jet shows that “plasma bullets” are formed even with water vapour in the gas mixture, but become quenched when the moist helium flow rate is above 300sccm (~1800ppm water concentration). Moderate amount of water vapour (~250ppm water concentration) is beneficial for active species production mainly due to the high electron density. Hydrogen peroxide production in saline solution with three different plasma sources is investigated due to the importance of H2O2 in several important applications. Long lifetime of H2O2 in the liquid after plasma treatment indicates an exciting possibility of plasma pharmacy.