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Extraction in alkali without nitrogen significantly alters physico-chemical properties of humic acids from compostтезисы доклада
- Авторы: Davydova I.Yu, Zavarzina A.G.
- Сборник: Book of Abstracts Seventh International Conference of the CIS IHSS on humic innovative technologies "Humic substances and technologies for resilience" (HIT-2022) November 18–21, 2022 Sailing Club "Vodnik", Moscow Region, Russia
- Тезисы
- Год издания: 2022
- Место издания: Moscow Region, Russia
- Первая страница: 16
- Последняя страница: 16
- DOI: 10.36291/HIT.2022.012
- Аннотация: Humic acids (HA) are formed during biotransformation of organic residues in the diversity ofthe environments and represent polydisperse and heterogeneous compounds enriched in polarfunctional groups. Alkaline extraction with subsequent acidification is traditional way to obtain HApreparations from soils and sediments. However, alkaline treatment is criticized for the possibilityof creating artifacts, such as oxidation of phenolic constituents, hydrolysis of ester groups, etc.International Humic Substances Society has recommended to perform alkaline extraction underthe atmosphere of inert gas (e.g. nitrogen). However, extraction under N2 is rarely used in humuschemistry and is ignored when HA are obtained for commercial purposes. Compost is one of thesources of commercial HA. It represents relatively fresh organic material if compare with peat,coal and soil humus. The aim of this work was to study the physico-chemical properties of HAfrom compost extracted by 0.1 M NaOH in absence or presence of oxygen.Compost prepared from leaves and grass with the time of composting of about 10 yearswas used as a source of the HA. Compost material was air dried and passed through 2 mmsieve. Extraction of the HA was performed by three consequtive treatments with 0.1 M NaOH (1hour each) under the N2 atmosphere (HA-N2) or without it (HA-O2). The pH of each extract wasadjusted to 7.0, extracts were pooled and purified by membrane filtration (0.22 mm). HA werethen obtained by acidification and air-dried.The infrared spectra of the preparations were identical as well as their molecular weightdistributions on Sephadex-G-75 gel. However HA-O2 was characterized by higher O:C and C:Nratios (0.6 and 13.6 respectively vs 0.5 and 12.5 in HA-N2), higher optical density at 465 nm(E0.001% 0.04 vs 0.03 in HA-N2), higher E4/E6 ratio (5.5 vs 4.7 in HA-N2), lower contribution of CHnfragments and higher contribution of CHn-O ones (17.3 and 21.2% respectively vs 22.9% and16.7% in HA-N2). The content of OC-O(N) (acetale) fragments was also higher in HA-O2. Thecontent of functional groups titrated in the regions of pH 5-8 and 8-10 were 4 and 2 times higherin the HA-O2 suggesting an increase in the content of COOH-groups and in the content of OHgroupsin this preparation.Thus, we have shown that alkaline extraction of HA from relatively fresh humic material(compost) significantly alters physico-chemical properties of HA if no N2 is applied. Mostsignificant changes occur in the functional groups content and in the content of aliphatic Ocontainingfragments. We hypothesize that changes occur in the functional properties of the HAas well. Alkaline treatment under O2 may enhance HA complexing and antioxidant capabilitiesand can be used as targeted modification of the HA preparations. We are testing this hypothesisin our current research.
- Добавил в систему: Заварзина Анна Георгиевна
Прикрепленные файлы
| № | Имя | Описание | Имя файла | Размер | Добавлен |
|---|---|---|---|---|---|
| 1. | HIT-2022-abstractbook.pdf | HIT-2022-abstractbook.pdf | 3,5 МБ | 13 января 2023 [AZavarzina] | |
| 2. | HIT-2022-abstractbook.pdf | HIT-2022-abstractbook.pdf | 3,5 МБ | 22 ноября 2022 [AZavarzina] |