Humic acid–cetyltrimethylammonium bromide interaction: a fluorimetric study

Abstract

Synchronous and excitation emission matrix fluorescence (EEMF) characteristics of humic acid-surfactant interaction have been studied. The variation of synchronous and EEMF spectral maxima and intensities with humic acid (HA)-cetyltrimethylammonium bromide (CTAB) composition sensitively reflects the extent of flocculation of HA. It was found that the concentration range for co-precipitation of HA-CTAB was similar for all concentrations (60 p.p.m., 80 p.p.m. and 100 p.p.m.) of humic acid studied. In the concentration range 60-150 p.p.m. of humic acid, the EEMF maximum is found at 460/540 nm, indicating the presence of ligneous materials. Fluorescence intensity measurement at this contour excitation/emission wavelength (460/540 nm) is suggested as a convenient and a sensitive method for studying the physical state of humic acid in the presence of cationic surfactants. No significant interaction of HA with sodium dodecylsulphate (SDS) and TX-100 was found.

Surfactant adsorption to soil components and soils

“…This may have lead to partial re-dispersion of the aggregates. Shang and Rice[110] and Subbiah and Mishra[111] investigated HA-C16TB complexes by,…”

Quest for the binding mode of malachite green with humic acid

“…Secondly, the fluorescence peak had significant red shifts (peak a, from 447.5 nm to 468.0 nm; peak c, from 454.0 nm to 469.1 nm), implying that MG binding could induce micro-environmental changes of fluorophores groups in HA. In addition, peak b was looked like disappear and clearly quenched by MG comparing with peak a and peak b, which indicated that the humic-like substance obviously reacted with MG and MG could enter into the hydrophobic cavities of HA [22]. Fig.…”

“…In addition, an obviously red shift of the HA fluorescence emission (from 455 nm to 469 nm) occurs. HA is a multichromophoric system which has different fluorescence groups [22]. The red shift of maximum emission wavelength suggested that the fluorescence groups were placed in a less hydrophobic environment and more fully exposed to the external environment [23].…”

Fluorescence spectroscopic investigation of the interaction between triphenyltin and humic acids

“…Therefore, many works have been carried out to characterize the binding of HA with some environmental pollutants. Subbian and Mishra have studied the interaction of humic acid with surfactant [10]. Nakashima et al have investigated the binding interaction of HA with heavy metal ions [8].…”

“…Humic acids (HA) are the major extractable component of soil humic substances and play a crucial role in removal and/or migration of environmental pollutants in natural water [8]. HA could bind with inorganic and organic contaminants through hydrophobic, electrostatic, hydrogen bonding, or coordinate bonding interaction [8,[10][11][12][13][14]. The binding constants and binding forces between environmental pollutants and HA are the great environmental concerns.…”