Recovery of titanium dioxide and other pigments from waste paint by pyrolysis

In this work, a model paint containing several types of inorganic pigments was pyrolyzed in a microwave-heated unit. The goal of the pyrolysis process was to recover and recycle the inorganic components in the paint, most importantly titanium dioxide (TiO₂). The solid residue remaining after pyrolysis was further heat treated in air to remove most of the char in the TiO₂-containing product. The recovered TiO₂-containing product was used in two types of paint formulation as a replacement for virgin pigments. The properties of the paints containing recycled TiO₂ pigment and extenders were evaluated and compared with a standard paint formulation containing only virgin TiO₂ pigment and virgin extenders. A reduction in paint whiteness was observed but the opacity, gloss, and durability were nearly equivalent to that of the standard paint. Another consequence of using recycled pigments was that the recycled mix of TiO₂ pigments and extenders was harder to disperse in the paint than the mix based on virgin materials, thus giving the painted surface a somewhat rough texture. The recycled material has shown promising results as a pigment/extender but further work is needed to optimize the recycled product to meet whiteness and dispersion requirements for incorporation in paint formulations on an industrial scale.