Pollution Prevention and Waste Minimization in Metal Finishing (SEER)EPA Grant Number: R827685E04
Title: Pollution Prevention and Waste Minimization in Metal Finishing (SEER)
Investigators: Mazumder, Malay K. , Engelken, Robert
Institution: University of Arkansas - Little Rock , Arkansas State University - Main Campus
EPA Project Officer: Winner, Darrell
Project Period: August 1, 1999 through July 31, 2001
RFA: EPSCoR (Experimental Program to Stimulate Competitive Research) (1999) RFA Text | Recipients Lists
Research Category: EPSCoR (The Experimental Program to Stimulate Competitive Research)
In the use of metals, from airframes to toys, the metal surface is painted for corrosion protection and for aesthetic appearance. A typical metal finishing process consists of three steps: (1) cleaning and pretreatment with a primer; (2) coating the surface with polymer paints; and (3) curing the paint to obtain a durable coat over the primer. In many applications, the metals are painted with a conventional spray process using volatile organic compounds (VOCs) mixed with the paints. During the curing process, toxic VOCs are emitted. These VOCs are carcinogenic and the U.S. Environmental Protection Agency has strict regulations on their emission. Because of this serious environmental problem, most industries are switching to powder-coating systems. In the powder-coating process, dry powder is deposited on metal surfaces by electrostatic spraying, and the deposited powder layer is cured to form a durable film. The coating process is functionally and economically competitive with the organic solvent-based paint.
The overall objective of this research project was to prevent pollution and minimize waste in metal coating (precoat plating and powder-coating) processes. The specific objectives of this research project, which involved pollution prevention and waste minimization, were to:
1. Replace hexavalent chromium used for precoating aluminum by a process that is environmentally safe and economically competitive. The hexavalent chromium can be replaced with liquid solution deposition of molybdenum or tungsten, or by reactive organic conversion coating processes.
2. Improve Faraday penetration of charged powder in recessed areas, and expand powder-coating applications to areas where solvent-based coatings currently are used. The goal was to improve transfer efficiency of the powder to more than 90 percent to reduce powder wastes in powder-coating processes where the recycling of powder is not feasible. Improved efficiency would allow fast color change without significant waste of powder.
The long-term goal of this research project was to be nationally competitive through undergraduate and graduate research and academic programs in environmental science and engineering, peer-reviewed publications, seminars and presentations, workshops, demonstrations, and training.