Synthesis of Humic and Fulvic Acids and their Characterization using Optical Spectroscopy (ATR-FTIR and UV-Visible)

Abstract

Humic substances (HS) are complex molecules characterized by high molecular weight and high chemical heterogeneity. In order to have a deeper understanding of these molecules, there is need to synthesize humic acids (HA) and fulvic acids (FA) with determined functional groups. In this paper we report a systematic study on the synthesis of both HA and FA as a function of pH and nature of the functional groups. HA and FA with two functional groups (phenolic and carboxylic) has been synthesized through polymerization of catechol and acetic acid, calibrated by dialysis with membranes of 500, 1000 and 10000 MWCO (Molecular Weight Cut Off) and characterized using two spectroscopic measurement techniques (ATR-FTIR and UV-Visible). Our synthesis technique is inexpensive and simple to undertake. There is no saturation of the reaction medium with oxygen.

Key words: Catechol, fulvic acid, humic acid, humic substances.