The present invention provides methods that are used to decolorize compositions containing one or more amines in the presence of one or more weak acids. Significantly, the weak acids, particularly organic acids such as glacial acetic acid, when used in combination with a heat treatment produce dramatically less by-products than do the stronger mineral acids, making heat treatments and subsequent separation techniques more effective while producing less waste. In some modes of practice, the weak acids do not need to be neutralized, eliminating neutralizing steps and waste streams associated with neutralization. Low color products can be obtained easily at very high yield as a consequence.