Toxicological assessment of pesticide contaminated soils with use of biotests

The paper presents the results of experiments on ecological toxicity assessment performed for 12 soil samples collected at 3 obsolete pesticide “tombs” in Poland, before their final disposal. Bioavailability of the main pollutants: p,p’-DDT, lindane and methoxychlor was assessed for selected samples by consecutive solid phase extraction using a Tenax TA sorbent. Several toxicity bioassays were also carried out, including: reducers (Microtox Soild Phase), producers (Phytotox) and consumers (tests of avoidance, acute toxicity and reproduction with use of the earthworm Eisenia foetida). Data from toxicity tests were discussed against the results of the chemical analysis of a wide range of pesticides determined by GC-ECD and GC-NPD. This part of the study enabled the evaluation of the applicability of the aforementioned bioassays in the assessment of pesticide soil pollution. Results of toxicity tests showed a slight to severe impairment of habitat function for all of the contaminated samples, which was only partially reflected by the analytical data. The most sensitive biotest was earthworm reproduction, followed by Phytotox and earthworm acute toxicity. Earthworm avoidance and Microtox tests were found to be of rather limited usability

Rapid continuous microwave-assisted synthesis of silver nanoparticles to achieve very high productivity and full yield : from mechanistic study to optimal fabrication strategy

Systematic studies of silver nanoparticle synthesis in a continuous-flow single-mode microwave reactor using polyol process were performed, revealing that the synthesis is exceptionally effective to give very small metal particles at full reaction yield and very high productivity. Inlet concentration of silver nitrate or silver acetate, applied as metal precursors, varied between 10 and 50 mM, and flow rates ranged from 0.635 to 2.5 dm3/h, to give 3–24 s reaction time. Owing to its much higher reactivity, silver acetate was shown to be far superior substrate for the synthesis of small (10–20 nm) spherical silver nanoparticles within a few seconds. Its restricted solubility in ethylene glycol, applied as the solvent and reducing agent, appeared to be vital for effective separation of the stage of particle growth from its nucleation to enable rapid synthesis of small particles in a highly loaded system. This was not possible to obtain using silver nitrate. All the observations could perfectly be explained by a classical LaMer–Dinegar model of NPs’ formation, but taking into account also nonisothermal character of the continuous-flow process and acetate dissolution in the reaction system. The performed studies indicate an optimal strategy for the high-yield fabrication of metal particles using polyol method

Rapid continuous microwave-assisted synthesis of silver nanoparticles to achieve very high productivity and full yield: from mechanistic study to optimal fabrication strategy

Systematic studies of silver nanoparticle synthesis in a continuous-flow single-mode microwave reactor using polyol process were performed, revealing that the synthesis is exceptionally effective to give very small metal particles at full reaction yield and very high productivity. Inlet concentration of silver nitrate or silver acetate, applied as metal precursors, varied between 10 and 50 mM, and flow rates ranged from 0.635 to 2.5 dm3/h, to give 3–24 s reaction time. Owing to its much higher reactivity, silver acetate was shown to be far superior substrate for the synthesis of small (10–20 nm) spherical silver nanoparticles within a few seconds. Its restricted solubility in ethylene glycol, applied as the solvent and reducing agent, appeared to be vital for effective separation of the stage of particle growth from its nucleation to enable rapid synthesis of small particles in a highly loaded system. This was not possible to obtain using silver nitrate. All the observations could perfectly be explained by a classical LaMer–Dinegar model of NPs’ formation, but taking into account also nonisothermal character of the continuous-flow process and acetate dissolution in the reaction system. The performed studies indicate an optimal strategy for the high-yield fabrication of metal particles using polyol method