Solubility and reactivity of surfactant-enhanced alkaline hydrolysis of organophosphorus pesticide DNAPL

Advances on removal of organophosphorus pesticides with electrochemical technology

Widespread use of organophosphorus pesticides (OPs), especially superfluous and unreasonable use, had brought huge harm to the environment and food chain. It is because only a small part of the pesticides sprayed reached the target, and the rest slid across the soil, causing pollution of groundwater and surface water resources. These pesticides accumulate in the environment, causing environmental pollution. Therefore, in recent years, the control and degradation of OPs have become a public spotlight and research hotspot. Due to its unique advantages such as versatility, environmental compatibility, controllability, and cost-effectiveness compatibility, electrochemical technology has become one of the most promising methods for degradation of OPs. The fundamental knowledge about electrochemical degradation on OPs was introduced in this review. Then, a comprehensive overview of four main types of practical electrochemical technologies to degrade pesticides were presented and evaluated. The knowledge contained herein should conduce to better understand the degradation of pesticides by electrochemical technology, and better exploit the degradation of pesticides in the environment and food. Overall, the objective of this review is to provide comprehensive guidance for rational design and application of electrochemical technology in the degradation of OPs for the safety of the environment and food chain in the future.

Self-Assembled Quaternary Ammonium-Containing Comb-Like Polyelectrolytes for the Hydrolysis of Organophosphorous Esters: Effect of Head Groups and Counter-Ions

The aim of this work was to increase the efficiency of catalytic systems for the hydrolytic cleavage of 4-nitrophenyl esters of phosphonic acids. Quaternary ammonium-containing comb-like polyelectrolytes («polymerized micelles») with ester cleavable fragments and a low aggregation threshold were used as catalysts. The synthesis of poly(11-acryloyloxyundecylammonium) surfactants with different counterions (Br^- , NO₃ ^- , CH₃ C₆ H₄ SO₃ ^- ) and head groups was realized by micellar free-radical polymerization. Molecular weight, critical association concentration, particle sizes and solubilization properties toward Orange OT were determined. Self-assemblies organized by poly(11-acryloyloxyundecyltrimethyl ammonium) bromide successfully catalyze the hydrolysis of 4-nitrophenyl butylchloromethylphosphonate up to two orders of magnitude compared to aqueous alkaline hydrolysis. The development of these catalysts is promising for industrial applications and organophosphorus compound detoxification.

Surfactant-Enhanced Solubilization of Chlorinated Organic Compounds Contained in DNAPL from Lindane Waste: Effect of Surfactant Type and pH

Application of surfactants in the remediation of polluted sites with dense nonaqueous phase liquid (DNAPL) still requires knowledge of partitioning between surfactants and pollutants in the organic and aqueous phases and the time necessary to reach this balance. Two real DNAPLs, generated as wastes in the lindane production and taken from the polluted sites from Sabiñanigo (Spain), were used for investigating the solubilization of 28 chlorinated organic compounds (COCs) applying aqueous surfactant solutions of three nonionic surfactants (E-Mulse^® 3 (E3), Tween^®80 (T80), and a mixture of Tween^®80-Span^®80 (TS80)) and an anionic surfactant (sodium dodecyl sulfate (SDS)). The initial concentrations of surfactants were tested within the range of 3–17 g·L⁻¹. The pH was also modified from 7 to >12. The uptake of nonionic surfactants into the organic phase was higher than the anionic surfactants. Solubilization of COCs with the nonionic surfactants showed similar molar solubilization ratios (MSR = 4.33 mmol_COCs·g⁻¹_surf), higher than SDS (MSR = 0.70 mmol_COCs·g⁻¹_SDS). Furthermore, under strong alkaline conditions, the MSR value of the nonionic surfactants was unchanged, and the MSR of SDS value increased (MSR = 1.32 mmol_COCs·g⁻¹_SDS). The nonionic surfactants did not produce preferential solubilization of COCs; meanwhile, SDS preferentially dissolved the more polar compounds in DNAPL. The time required to reach phase equilibrium was between 24 and 48 h, and this contact time should be assured to optimize the effect of the surfactant injected on COC solubilization.