Surface properties of humic acids from peat and sapropel of increasing transformation

Abstract

Humic substances are complex, organic substances occurring in natural media such as water, soils and sediments. Humic substances represent the highest pool of recent carbon on earth, and they influence climate, soil fertility and depollution. In spite of such importance, the structure and properties of humic substances are largely unknown. We studied the surfactant activity of humic acids from peat of increasing degrees of humification and sapropel, sampled in the Upa River of the Tula region. We measured critical micelle concentration (CMC) of humic acids of different ages. Our results show that CMC decreases from 1.5 g/100 ml for the less transformed sapropel, to 1.0 g/100 ml for the medium-transformed mesotrophic sphagnum peat, to 0.25 g/100 ml for the most transformed eutrophic alder peat. We also found that the limiting adsorption of humic acids from the younger sapropel, of 7.1 9 10 -6 mol/m 2 , and from sphagnum peat, of 7.6 9 10 -6 mol/m 2 , are higher than the limiting adsorption of humic acids from the older eutrophic alder peat, of 3.3 9 10 -6 mol/m 2 .

The Key Role of Sulfate in the Photochemical Renoxification on Real PM2.5

“…This HA+SO 4 2− sample (with 7.9 × 10 −6 mol NO 3 − ) exhibited a significant rate of photochemical renoxification (Figure 5a, P = 3.9 × 10 −11 mol•s −1 ). Many OMs of PM 2.5 can absorb light of λ > 350 nm (Figure S2 and S3), both in WSM, such as HULIS, 38,39 and in the WISM part, such as polycyclic aromatic hydrocarbons (PAHs). 40−43 These observations suggest that these light absorbers (e.g., HULIS and PAHs) on PM 2.5 act as antennas to absorb light and photosensitize the renoxification reaction, which is different from the reported renoxification pathway initiated by the light absorption of HNO 3 itself.…”

Assessment of sapropel use for pharmaceutical products according to legislation, pollution parameters, and concentration of biologically active substances

“…Humic substances make up the highest recent amount of carbon on earth that can affect the climate, soil fertility, and degradation 48 . The properties of polyphenols in humus substances in cosmetics and medicine can be used as antioxidants.…”

Methods of Dehydration of Sapropel

“…В его состав входят два основных компонента: высушенный торф (влажность 27 %) и сапропель естественной влажности (85% -97%) [36]. Преимуществом этой технологии является отсутствие длительной сушки сапропеля, но обезвоживание торфаэнергозатратный и длительный процесс [37,38,39].…”