Zheng Wei

Date of Award


Degree Name

Master of Science


Chemical and Paper Engineering

First Advisor

Dr. Paul D. Fleming III

Second Advisor

Dr. John Cameron

Third Advisor

Dr. Jan Pekarovic


ultrasound, deinking, paper recycled, indigo, ElectroInk

Access Setting

Masters Thesis-Open Access


Digital printing plays a very important role in the life of modern society. With the development of digital printing technologies, and the increasing market share of digital printing, the amount of digital prints in waste paper is rapidly increasing. Under “green” manufacturing and environmental sustainability, deinking of digital print inks is an urgent problem that needs to be solved. Indigo is a typical series of HP (Hewlett-Packard) digital presses that use a liquid ink named ElectroInk (Liquid Electrophotography or LEP). The particle size of HP ElectroInk is very small, 1-2 microns, which is smaller than dry toners. But, during flotation, the ink platelets were too big to be removed by foaming.

In this research, we focus on a new way of deinking that uses ultrasound treatment. Ultrasound could break down the ink platelets and then help the ink detachment from fiber. During the deinking processes, we choose both neutral and alkaline environments. For different ultrasound times, we will compare the results using a variety of Indigo certified substrates at 20 kHz. ElectroInks can be detached by ultrasound treatment and then we can remove them by conventional flotation technology.