Separation of ink particles from waste paper by fine-bubbles

Abstract

This article describes the research leading to the development of a new process for f lotation deinking of waste paper, including old newsprint (ONP), magazines, etc. The technique involves a simple reagent scheme (ammonium hydroxide or sodium bicarbonate) that can be used at room temperature to generate fine bubbles at the ink/fiber/water interface that help in the ink particle detachment as well as in rendering ink particles hydrophobic. The reagents also act on desorbing organic species (oil) from oil-based ink, thereby stabilizing the bubbles. A self-aeration f lotation machine could be used to enhance f lotation kinetics. Experimental studies have been conducted to evaluate different operating conditions, including reagent dosage, f lotation time, recycling f lotation water, etc. The efficiency of the process is evaluated in terms of yield of clean pulp, brightness, and reagent consumption.