Desorption process and morphological analysis of real polycyclic aromatic hydrocarbons contaminated soil by the heterogemini surfactant and its mixed systems

Surfactant-enhanced remediation (SER) is an efficient and low-cost technology for polycyclic aromatic hydrocarbons (PAHs) contaminated sites. This study assessed the desorption processes and effects of Heterogemini surfactant (Dodecyldimethylammonium bromide/tetradecyldimethylammonium bromide, DBTB), two traditional surfactants (Hexadecyl trimethyl ammonium bromide, CTAB; Sorbitan monolaurate, Span 20) and their mixed systems on the real PAHs-contaminated soil from an abandoned coking plant, as well they were analyzed micro morphologically. DBTB had greater desorption capability for PAHs and favorable interaction with the traditional surfactants confirmed by reaction parameters β^m and Gibbs. Whether for total PAHs (TPAHs) or different molecular weight PAHs, the mixed system Span 20/DBTB had larger molar solubilization ratio (MSR) and partition coefficient (K_m) than CTAB/DBTB, the highest desorption rate for TPAHs reaching 68.83%. Additionally, microscopic morphology showed micelles of Span 20/DBTB were more dispersed and formed strings easily, explaining its good desorption capability. What resulted demonstrated the feasibility of DBTB, a novel Heterogemini surfactant, and its mixed systems remediating PAHs-contaminated soil of abandoned industrial site.

Synthesis, Characteristics and Application of Novel Non-Ionic Gemini Surfactants as Reverse Micellar Systems for Encapsulation of Some Aromatic α-Amino Acids in n-Hexane

Non-ionic carbohydrate based gemini surfactants with rigid aromatic spacer CH2-Ar-CH2, which carry two hydrophobic tails of different tail lengths (C12, C14 and C16) and two sugar moiety polar head groups were synthesized and their reverse micellar behavior for solubilization of some aromatic α-amino acids viz. histidine (His), phenylalanine (Phy), tyrosine (Tyr) and tryptophan (Trp) in n-hexane were studied by spectroscopic analysis. The head group of these gemini surfactants consists of sugar moiety connected to C-6 of tertiary amines. Amino acids form complexes in order of His > Phy > Tyr > Trp, and in all cases it was found that the D-enantiomers solubilize better in comparison to the L-enantiomers. Moreover, more hydrophobic surfactants i.-e. surfactants with longer hydrocarbon tails show greater complex formation tendency towards D- and L-enantiomers of aromatic α-amino acids.