Comparative study on the biodegradability of morpholinium herbicidal ionic liquids

Abstract

This study focused on evaluating the toxicity as well as primary and ultimate biodegradability of morpholinium herbicidal ionic liquids (HILs), which incorporated MCPA, MCPP, 2,4-D or Dicamba anions. The studied HILs were also subjected to determination of surface active properties in order to assess their influence on toxicity and biodegradability. The study was carried out with microbiota isolated from different environmental niches: sediments from river channel, garden soil, drainage trench collecting agricultural runoff stream, agricultural soil and municipal waste repository. The obtained results revealed that resistance to toxicity and biodegradation efficiency of the microbiota increased in the following order: microbiota from the waste repository > microbiota from agricultural soil ≈ microbiota from an agricultural runoff stream > microbiota from garden soil > microbiota from the river sludge. It was observed that the toxicity of HILs increased with the hydrophobicity of the cation, however the influence of the anion was more notable. The highest toxicity was observed when MCPA was used as the anion (EC50 values ranging from 60 to 190 mg L−1). The results of ultimate biodegradation tests indicated that only HILs with 2,4-D as the anion were mineralized to some extent, with slightly higher values for HILs with the 4-decyl-4-ethylmorpholinium cation (10–31 %) compared to HILs with the 4,4-didecylmorpholinium cation (9–20 %). Overall, the cations were more susceptible (41–94 %) to primary biodegradation compared to anions (0–61 %). The obtained results suggested that the surface active properties of the studied HILs may influence their toxicity and biodegradability by bacteria in different environmental niches.

Synthesis and Structure–Property Relationships in Herbicidal Ionic Liquids and their Double Salts

“…Hence, the values of CA as well as CMC were generally notably higher for 2 c – 7 c compared to 2 b – 7 b (see Table S8). These results are consistent with previous data describing other MCPA‐ and dicamba‐based ILs with common tetraalkylammonium cations, as well as with notably lower values of log K OW for 2 c – 7 c , indicating their greater affinity for water (see Figure A).…”

Herbicidal Ionic Liquids Containing the Acetylcholine Cation

“…In the most desired scenario the bio‐based cation should enhance the biodegradation rate of the herbicidal anion . It should also be noted that the test was carried out with the use of activated sludge microorganisms and that the biodegradability of the studied compounds in agricultural soils may differ . Furthermore, fully synthetic ILs may notably decrease the biodiversity of microbial populations on the example of phosphonium‐based ILs or ammonium‐based ILs, whereas HILs did not significantly impact the overall biodiversity or did not exhibit mutagenic properties .…”

“…Introduction of the organic cation of natural origin into the structure of HIL may result in lowering the toxicity of the anion ,. Moreover, herbicidal ionic liquids may be applied at lower dose in comparison to the commercial substances ,,,,,. Natural‐derived compounds characterized by common accessibility, renewability and biodegradability are in scope of research by scientists around the world ,.…”

“…[7,23] Moreover, herbicidal ionic liquids may be applied at lower dose in comparison to the commercial substances. [5,7,11,13,17,24] Natural-derived compounds characterized by common accessibility, renewability and biodegradability are in scope of research by scientists around the world. [23,25] Choline-derivative-based ionic liquids are known in the literature.…”

Quaternary ammonium nonanoate-based ionic liquids as chemicals for crop protection

“…IL 1 reduced the surface tension of water to 21.86 mN/m which is a very good result. On the other hand, the remaining two nonanoates reduced the surface tension value to 26-28 mN/m which is characteristic for cationic surface active compounds [50].…”