Structural Changes of Humic Acids During Olive Mill Pomace Composting

• Published in: Compost science & utilization Vol. 9; no. 2; pp. 134 - 142
• Main Authors: Tomati, U., Madejon, E., Galli, E., Capitani, D., Segre, A.L.
• Format: Journal Article
• Language: English
• Published: Emmaus,PA Taylor & Francis 01.03.2001; JG Press; Taylor & Francis Ltd
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Food industries; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; olive mills; Other nutrients. Amendments. Solid and liquid wastes. Sludges and slurries; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Use and upgrading of agricultural and food by-products. Biotechnology; Waste treatment; Aliphatic compound; Chain length; Chemical structure; Polymerization; NMR spectrometry; Oxygen content; Fourier spectrometry; Molecular weight; Gel permeation chromatography; Vegetal waste; Olive; Composting; Chemical modification; Carbon content; Biopolymer; Carboxyl group; Oil plant by product; Aromatic compound; Biological treatment; Polysaccharide; Humic acid; Functional group
• ISSN: 1065-657X; 2326-2397
• DOI: 10.1080/1065657X.2001.10702027

The aim of this work was to characterize the humic acids during composting using both chemical and spectroscopic analytical methods. Humic acids (HA) were extracted from olive mill pomace (OMP) after 5, 10, 21, 32, 48, 60, 84, 95, 109 and 153 days of composting and their elemental composition, functional groups, molecular weight, 13 C CP-MAS NMR and FTIR spectra were determined. Elemental composition of HA showed a decrease of carbon content from 56.8% to 47.1% and an increase of oxygen content from 32.7 % to 43.3%. A slight increase of carboxylic groups was observed with no variation of phenolic groups. The molecular weight of HA determined by gel chromatography showed that after 95 days of composting the molecular weight of about 40% of the polymers was greater than 10 2 KDalton. The 13 C CPMAS NMR and FTIR spectra of HA showed compositional and structural changes indicating a slight increase of polysaccharides and aromatic groups and a decrease of long aliphatic chains during the composting.