title: 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.
authors.affiliation: Department of Chemistry, Indian Institute of Technology, Madras, India.
authors.forename: Deepa
authors.initials: D
authors.lastname: Subbiah
authors.forename: Ashok Kumar
authors.initials: AK
authors.lastname: Mishra
mesh_terms: D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry*; D002614:Chelating Agents / Q000737:chemistry; D011232:Chemical Precipitation; D005470:Fluorometry / Q000379:methods*; D006812:Humic Substances; D017830:Octoxynol; D012967:Sodium Dodecyl Sulfate; D013501:Surface-Active Agents / Q000737:chemistry
chemical_list: D002593:Cetrimonium Compounds; D002614:Chelating Agents; D006812:Humic Substances; D013501:Surface-Active Agents; D012967:Sodium Dodecyl Sulfate; D017830:Octoxynol; D000077286:Cetrimonium