The occurrence of alachlor in natural drinking water sources raises concerns due to adverse health effects. Advanced oxidation with zero valent iron activating persulfate (ZVI/PS) can degrade alachlor with great potential. But no information was reported about effect of ZVI/PS preoxidation on the generation of disinfection byproducts (DBPs) during the downstream chlorination of alachlor. The objective was to investigate DBP formation through chlorination of alachlor preoxidized by ZVI/PS. The results found that ZVI/PS preoxidation enhanced the DBP formation, compared with original system without any treatment. The longer the preoxidation time of ZVI/PS during the experiment, the more DBPs that were generated. During 48.0 h chlorination time, the produced DBPs increased to a stable value. Nitrate posed almost no impact on the DBP formation in the ZVI/PS system, while chloride significantly decreased DBP formation, which was attributed to the reduction of trichloromethane. During the chlorination process, alachlor could be further oxidized by remaining PS and free chlorine collectively. ZVI/PS had little effect on the DBP formation in the real water matrix. However, it could reduce carbonaceous DBP formation and increase nitrogenous DBP formation when the real water matrix contained 100 μg/L alachlor. The acute toxicity of alachlor solution could be reduced by the ZVI/PS system, while after chlorination the acute toxicity was largely increased due to the formation of DBPs. With increase of PS concentration, the DBP formation decreased in the ZVI/PS preoxidation system and increased in the system with PS alone. In conclusion, application of ZVI/PS in actual water containing alachlor declined DBP generation by augmenting PS concentration which should consider standard limited value of sulfate. Further investigation is needed for high bromide water.
Red-emissive nitrogen doped carbon quantum dots (N-CQDs) were synthesized by a facile and efficient microwave-assisted hydrothermal treatment of p-phenylenediamine (p-PD), and then applied for the highly selective and sensitive fluorescence detection of the alachlor herbicide in soil samples. The synthesized N-CQDs exhibited strong red emission with a 27.6% quantum yield (QY) and high stability. Under the optimized experimental conditions, the as-prepared red-emissive N-CQDs were employed as a fluorescent probe to successfully detect trace alachlor, and their fluorescence presented a good linear decline with the increase of the alachlor concentration from 0.005 to 150 μM with a limit of detection of 0.2 nM. The N-CQDs as a fluorescent probe were used for the detection of alachlor in soil samples with satisfactory recoveries ranging from 86.6–114.3%, indicating that they were a promising fluorescent probe for highly selective and sensitive determination of alachlor.
In this study we constructed a heterogeneous Fenton system with ascorbic acid (AA), magnetite (Fe 3 O 4 ) and H 2 O 2 for the alachlor degradation, aiming to clarify the heterogeneous Fenton mechanism. The addition of AA could significantly accelerate the Fenton reaction by promoting the surface Fe(III)/Fe(II) redox cycle (iron cycle) of Fe 3 O 4 . A kinetic model was successfully developed to quantitatively describe the complicated reactions in the Fe 3 O 4 /AA/H 2 O 2 system. We thus employed this model to identify the individual contributions of surface and homogeneous Fenton reactions to the overall alachlor degradation in the Fe 3 O 4 /AA/H 2 O 2 system, and found the surface Fenton reaction was mainly responsible for the alachlor degradation with more than 62.6% of contribution. This work offers a new strategy to improve the heterogeneous Fenton activity via promoting surface Fenton reaction, and sheds light on the possibility to quantitatively describe and predict the heterogeneous Fenton processes with first principle kinetic models.
Zepeng Li,Yuxiang Wu,Zijing Li,Binger Yu,Xinyi Mao,Guoqing Shi
Acetochlor is an endocrine disruptor. The acetochlor residue is strongly lipophilic and can be enriched into products during the manufacturing process. In this study, we found that dimethyl-β-cyclodextrin (DM-β-CD) solution could decrease the apparent oil/water partition coefficient (Koil–w) of acetochlor and increase the sensitivity of fluorescence lateral flow immunoassay (LFIA) for acetochlor simultaneously. Based on this, a simple LFIA method for the determination of acetochlor and alachlor residues in vegetable oil was established. The detection process only involves vortex mixing of an oil sample and dimethyl-β-cyclodextrin solution in a 1 : 3 (V/V) ratio, loading the water phase onto the immunoassay strips and reading the results. Under optimized conditions, the LOD for acetochlor in oil was 3.53 ng g−1, and the working range was 12.03–2000.00 ng g−1. The recoveries of spiked samples ranged from 91.69% ± 1.12% to 112.23% ± 2.20%. Meanwhile, the cross reactivity for alachlor was 108.22%, while for other investigated acetochlor analogues it was less than 1%, and the recoveries of alachlor were from 92.90% ± 8.03% to 113.53% ± 3.40%, which indicate that this method can detect acetochlor and alachlor simultaneously. Compared with the traditional detection method, the pre-treatment process of the proposed method is “green” and simple, and can be applied to the on-site rapid detection of acetochlor and alachlor in vegetable oil and can provide inspiration for the detection of other lipophilic pollutants.
危险品化学品经营许可证（带存储）