Intermittent multi-generational reproductive toxicities of 1-alkyl-3-methylimidazolium tetrafluoroborate with essential involvement of lipid metabolism.

Ionic liquids (ILs) become emerging environmental pollutants. Especially, alkyl imidazolium ILs commonly showed stimulation in toxicological studies and mechanisms remained to be explored. In the present study, alkyl imidazolium tetrafluoroborate ([amim]BF4), with ethyl ([emim]), hexyl ([hmim]) and octyl ([omim]) as side-chains, were chosen as target ILs. Their toxicities on the reproduction and lifespan of Caenorhabditis elegans were explored with two types (A and B) exposure arrangements to mimic realistic intermittent multi-generational exposure scenarios. In type A scenario, there was an exposure every 4 generations with 12 generations in total, and in type B one, there was an exposure every two generations with 12 generations in total. Result showed that [emim]BF4 caused inhibition on the reproduction in 8 generations in type A exposure but 6 ones in type B exposure. Meanwhile, [hmim]BF4 showed inhibition in one generation and stimulation in 3 generations in type A exposure, but stimulation in 6 generations in type B exposure. Also, [omim]BF4 showed stimulation in one generation in type B exposure. Collectively, the results demonstrated less frequencies of inhibition, or more frequencies of stimulation, in the exposure scenario with more frequent exposures. Further mechanism exploration was performed to measure the lipid storage and metabolism in the aspect of energy supply. Results showed that [emim]BF4, [hmim]BF4 and [omim]BF4 commonly stimulated the triglyceride (TG) levels across generations. They also disturbed the activities of glycerol-3-phosphate acyltransferase (GPAT) and acetyl CoA carboxylase (ACC) in lipogenesis, those of adipose triglyceride lipase (ATGL) and carnitine acyl transferase (CPT) in lipolysis, and also the contents of acetyl-CoA (ACA). Further data analysis indicated the energy allocation among life traits including reproduction, antioxidant responses and hormone regulations.

New Insight into CO2 Reduction to Formate by In Situ Hydrogen Produced from Hydrothermal Reactions with Iron.

To reveal the nature of CO2 reduction to formate with high efficiency by in situ hydrogen produced from hydrothermal reactions with iron, DFT calculations were used. A reaction pathway was proposed in which the formate was produced through the key intermediate species, namely iron hydride, produced in situ in the process of hydrogen gas production. In the in situ hydrogenation of CO2, the charge of H in the iron hydride was -0.135, and the Fe-H bond distance was approximately 1.537 Å. A C-H bond was formed as a transition state during the attack of Hδ- on Cδ+. Finally, a HCOO species was formed. The distance of the C-H bond was 1.107 Å. The calculated free energy barrier was 16.43 kcal/mol. This study may provide new insight into CO2 reduction to formate in hydrothermal reactions with metal.

Potential application of carbohydrate biomass in hydrometallurgy: one-pot reduction of metal oxides/salts under mild hydrothermal conditions.

Carbohydrate biomass can be employed as a reductant for metallic material preparation due to it possessing diverse reducing functional groups. The reported studies focused on reduction of metal ions in acidic solution with the aid of biomass. However, we found alkali hydrothermal conditions are favorable to metal compound reduction, even direct conversion of metal oxides to metals. Based on our previous research on direct reduction of CuO and NiO into the corresponding metals, herein, conversion of other metal oxides (Fe2O3, MnO2, Co3O4, PbO2) with glucose was investigated to illustrate the universal applicability of direct reduction of metal oxides with carbohydrates under alkali hydrothermal conditions. Furthermore, metal salt reduction by carbohydrates was studied and the reduction performance of glucose and cellulose with and without alkali was compared. The results showed an alkaline hydrothermal environment is more conducive to metal reduction. Unlike the complete reduction of CuO and NiO, oxides of Fe(iii), Mn(iv), Co(iii) and Pb(iv) can only be partially reduced under the experimental conditions. Not only carbohydrates but also decomposed intermediates can reduce metal oxides or salts. In addition, due to the formation of stable complexes between the anions of salts and the decomposition products of carbohydrates, the reduction effects of various copper salts are significantly different. This study may provide an alternative approach to metal preparation in hydrometallurgy.

[Mechanism of coagulation treatment to leachate from MSW incineration].

Al2 (SO4), FeCl3, PAC and PAFC were used to coagulate the effluent of MSW incineration leachate after biochemical treatment, and mathematical models for COD removal were set up as well. The results show that COD removal rates are 20%, 17%, 30% and 40% respectively with addition of 500 mg x L(-1) Al2 (SO4)3, FeCl3, PAC and PAFC alone at pH 6. The < 2 000 fraction contains mainly dissolved organics from the leachate after biochemical treatment. Moreover, according to the analysis of Zeta potential and transmission electron microscope (TEM), the main mechanisms of the leachate coagulation can be explained as electrical neutralization, netting and bridging. As a matter of fact, compared to inorganic coagulants, the poly coagulants show higher capacity on these three functions.

[Kinetics of Electro-Fenton treatment of leachate from municipal solid waste incinerator].

SPR electrode was used in Electrio-Fenton treatment on the effluent from biological and coagulative treatments of solid waste incinerator leachate, at the same time, the kinetics model for the COD effluent concentration were set up. The result indicated that the disposal curve of COD confirm to the pseudo third order kinetics, and the formula is c(t) = (2kt + c(0)(-2))(-0.5), in which the c(t) is the COD concentration of treatment effluent. With the statistical analysis to the disposal curve of COD from Electro-Fenton treatment in different conditions, the experience mathematics model of k value was set up, in which the current density, pH value and COD concentration of influent are effective factors. Moreover, with the comparison between the simulative COD of effluent and the experimental results, it was showed that this kinetic model could be used to investigate the COD disposal efficiency of Electro-Fenton treatment on the effluent from biological and coagulative treatments of solid waste incinerator leachate preferably.

[Kinetics of catalytic wet air oxidation of phenol in trickle bed reactor].

By using a trickle bed reactor which was designed by the authors, the catalytic wet air oxidation reaction of phenol on CuO/gamma-Al2O3 catalyst was studied. The results showed that in mild operation conditions (at temperature of 180 degrees C, pressure of 3 MPa, liquid feed rate of 1.668 L x h(-1) and oxygen feed rate of 160 L x h(-1)), the removal of phenol can be over 90%. The curve of phenol conversion is similar to "S" like autocatalytic reaction, and is accordance with chain reaction of free radical. The kinetic model of pseudo homogenous reactor fits the catalytic wet air oxidation reaction of phenol. The effects of initial concentration of phenol, liquid feed rate and temperature for reaction also were investigated.