Visualizations of offset and flexographic inks at bubble surfaces.Application: This report describes a test method for Use in evaluating effectiveness of bubbles for ink Removal in DAF and flotation systems. ********** This paper presents results from a technique that provides visualization and imaging of ink particles in flows around bubbles to characterize ink adsorption adsorption, adhesion of the molecules of liquids, gases, and dissolved substances to the surfaces of solids, as opposed to absorption, in which the molecules actually enter the absorbing medium (see adhesion and cohesion). at bubble surfaces. The goal is to further the understanding of dissolved air flotation Dissolved air flotation (DAF) is a water treatment process that clarifies wastewaters (or other waters) by the removal of suspended matter such as oil or solids. The removal is achieved by dissolving air in the water or wastewater under pressure and then releasing the air at and flotation deinking processes important to paper recycling Paper recycling is the process of recovering waste paper and remaking it into new paper products. There are three categories of paper that can be used as feedstocks for making recycled paper: mill broke, pre-consumer waste, and post-consumer waste. . Our technique and experiments provide high resolution and high-speed video and images of ink attachment and interactions at bubble surfaces. An image processing image processing Set of computational techniques for analyzing, enhancing, compressing, and reconstructing images. Its main components are importing, in which an image is captured through scanning or digital photography; analysis and manipulation of the image, accomplished method is described that determines the sizes and number of adsorbed ink particles. We studied single bubbles ranging in diameter from 0.2 to 2 mm as they interacted with ink in model solutions and dispersions in a stationary bubble facility and a bubble suspending facility designed to model the flow in a DAF unit. The results in this paper are for model ink solutions with sodium oleate oleate /ole·ate/ (o´le-at) 1. a salt, ester, or anion of oleic acid. 2. a solution of a substance in oleic acid; used as an ointment. o·le·ate n. 1. at 100 mg/L, calcium chloride calcium chloride, CaCl2, chemical compound that is crystalline, lumpy, or flaky, is usually white, and is very soluble in water. The anhydrous compound is hygroscopic; it rapidly absorbs water and is used to dry gases by passing them through it. at 100 mg/L, and pH at 7.5 to 11.5. CONCLUSIONS AND APPLICATION The images from this study show that offset ink readily adsorbs to bubble surfaces for pH 8.5 and higher. Water-based flexographic ink interacting with stationary and suspended bubbles did not exhibit adsorption in solutions based on fatty-acid chemistry, even in instances where the bubble was fully shrouded by a layer of flexo ink. The stationary bubble facility and imaging system is fairly inexpensive and easy to operate, perhaps providing a replicable apparatus mills can use to screen chemicals and ink types to determine if ink attachment is probable. The bubble suspending column is more complex and the imaging of the moving bubbles is difficult, but it provides a means of studying ink and bubble interactions characteristic of DAF and flotation deinking. Davies and Duke are with the Department of Chemical Engineering, Auburn University Auburn University, main campus at Auburn, Ala.; land-grant and state supported; opened 1859 as East Alabama Male College, reorganized 1872 as the Agricultural and Mechanical College of Alabama; became coeducational 1892; renamed Alabama Polytechnic Institute 1899, , Alabama 36849-5127, USA; email Duke at srduke@eng.auburn.edu |
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