1-Methyl-3-octylimidazolium Chloride—Sorption and Primary Biodegradation Analysis in Activated Sewage Sludge

Abstract

Ionic liquids (ILs) are known to be non-volatile and thus to have low potential for atmospheric contamination or intoxication of humans by inhalation. However ILs have the potential to contaminate soil and water as they might be water soluble and can be sorbed onto solids. The investigation of possible natural ways of reducing the concentration of ILs in the environment is of high importance, especially because the requirement for biodegradable chemicals increases, together with pressure for reduction of incineration and landfill waste. It was found that the upper concentration threshold for primary biodegradation of 1-methyl-3-octylimidazolium chloride is 0.2 mM. At higher concentrations the dehydrogenase activity of the cells dropped markedly, indicating that the IL inhibits cell activity. This concentration is in good agreement with the minimal inhibitory concentration of the same compound found for a series of bacteria and fungi by this research group. The sorption of 1-methyl-3-octylimidazolium chloride was found to be significant, and the sorption coefficient was determined to be 98.2 L kg-1.

Influence of newly synthesized imidazolium ionic liquids on activated sludge process

“…The lack of adsorption is explained by the fact that the electrostatic and hydrophobic attractive forces are not suffi cient to absorb the tested ionic liquid under given conditions (Gorman-Lewis & Fein 2004). The activated sludge is a more complex adsorbent, therefore the study of adsorption on this material may give different results, what was confi rmed by Markiewicz et al (2009). They described an adsorption process of 1-methyl-3--octylimidazolium chloride [Omim][Cl] onto activated sludge and have found a high level of sorption of tested IL.…”

“…They described an adsorption process of 1-methyl-3--octylimidazolium chloride [Omim][Cl] onto activated sludge and have found a high level of sorption of tested IL. This result shows that sorption plays a signifi cant role in the removal of xenobiotics from wastewater (Markiewicz et al 2009). …”

“…The highest values of sorption coeffi cient were observed for [HMIM][Cl] and for IL 6 with six carbon atoms in the alkyl chain, as well. It may be due to Van der Waals strong interactions between the adsorbent and solution of the tested compounds having more hydrophobic alkyl chains (Markiewicz et al 2009). The infl uence of the adsorbent composition and lipophilicity of ionic liquids on the adsorption process was confi rmed in many reports (Beaulieu et al 2008, Studzińska et al 2008.…”

Activity of dehydrogenases in clay soil exposed to quaternary ammonium salts with iodine anion

“…1). Liwarska-Bizukojc (2011) also reported the inhibitory effect of 1-alkyl-3-methylimidazolium bromides on the activity of dehydrogenases in activated sludge biomass, which increased with the increase in the chain length of the alkyl substituent, whereas Markiewicz et al (2009) estimated that at 1-methyl-3-octylimidazolium chloride of concentration higher than 0.2 mM, the activity of dehydrogenases in the cells dropped markedly. Also Azimova et al (2009) measured the effect of imidazolium-derived ionic liquids on the bacterial respiration rate.…”

Ionic Liquids: Methods of Degradation and Recovery

“…Markiewicz et al showed that a level of 0.2mM 1-methyl-3-octylimidazolium chloride is the terminal concentration threshold for primary biodegradation. Higher concentrations led to sorption onto the sewage sludge flocs, although inhibition of cell function as a consequence of decreased dehydrogenase activity was observed (Markiewicz et al, 2009). This indicates that the toxicity of ILs towards activated-sludge microorganisms should be taken into consideration.…”