Selective anchoring of Pt NPs on covalent triazine-based frameworks via in situ derived bridging ligands for boosting photocatalytic hydrogen evolution.

The efficient and stable production of hydrogen (H2) through Pt-containing photocatalysts remains a great challenge. Herein, we develop an effective strategy to selectively and uniformly anchor Pt NPs (∼1.2 nm) on a covalent triazine-based framework photocatalyst via in situ derived bridging ligands. Compared to Pt/CTF-1, the obtained Pt/AT-CTF-1 exhibits a considerable photocatalytic H2 evolution rate of 562.9 µmol g-1 h-1 under visible light irradiation. Additionally, the strong interaction between the Pt NPs and in situ derived bridging ligands provides remarkable stability to Pt/AT-CTF-1. Experimental investigations and photo/chemical characterization reveal the synergy of the in situ derived bridging ligands in Pt/AT-CTF-1, which can selectively anchor the Pt NPs with homogeneous sizes and efficiently improve the transmission of charge carriers. This work provides a new perspective toward stabilizing ultrasmall nanoclusters and facilitating electron transfer in photocatalytic H2 evolution materials.

Overcoming Electrostatic Interaction via Strong Complexation for Highly Selective Reduction of CN- into N2.

Limited by the electrostatic interaction, the oxidation reaction of cations at the anode and the reduction reaction of anions at the cathode in the electrocatalytic system nearly cannot be achieved. This study proposes a novel strategy to overcome electrostatic interaction via strong complexation, realizing the electrocatalytic reduction of cyanide (CN- ) at the cathode and then converting the generated reduction products into nitrogen (N2 ) at the anode. Theoretical calculations and experimental results confirm that the polarization of the transition metal oxide cathodes under the electric field causes the strong chemisorption between CN- and cathode, inducing the preferential enrichment of CN- to the cathode. CN- is hydrogenated by atomic hydrogen at the cathode to methylamine/ammonia, which are further oxidized into N2 by free chlorine derived from the anode. This paper provides a new idea for realizing the unconventional and unrealizable reactions in the electrocatalytic system.

Degradation of pesticide wastewater with simultaneous resource recovery via ozonation coupled with anaerobic biochemical technology.

The effective treatment of pesticide wastewater with high organic content, complex composition and high-toxicity has attracted enormous attention of researchers. This work proposes a new idea for removing the pesticide wastewater with simultaneous resource recovery, which is different from the traditional view of mineralization of pesticide wastewater via composite technology. This novel strategy involved a sequential three-step treatment: (a) acidic Ozonation process, to remove the venomous aromatic heterocyclic compounds; (b) hydrolysis and ozonation in alkaline conditions, enhancing the biodegradability of pesticide wastewater, mainly due to the dehalogenation, elimination of C=C bonds and production of low molecular-weight carboxylate anions; (c) the final step is anaerobic biological reactions. Based on the characterizations, this two-stage acidic-alkaline ozonation can efficiently degraded the virulence of pesticide wastewater and enhance its biodegradability from 0.08 to 0.32. The final anaerobic biochemical treatment can stably remove the residuals and convert the low molecular-weight organics into CH4, achieving the resource recovery. This work explored the pH-dependent of ozonized degradation of pesticide wastewater and gives a new perspective of wastewater treatment.

Mineralization of cyanides via a novel Electro-Fenton system generating •OH and •O2.

Traditional methods of cyanides' (CN-) mineralization cannot overcome the contradiction between the high alkalinity required for the inhibition of hydrogen cyanide evolution and the low alkalinity required for the efficient hydrolysis of cyanate (CNO-) intermediates. Thus, in this study, a novel Electro-Fenton system was constructed, in which the free cyanides released from ferricyanide photolysis can be efficiently mineralized by the synergy of •OH and •O2-. The complex bonds in ferricyanide (100 mL, 0.25 mM) were completely broken within 80 min under ultraviolet radiation, releasing free cyanides. Subsequently, in combination with the heterogeneous Electro-Fenton process, •OH and •O2- were simultaneously generated and 92.9% of free cyanides were transformed into NO3- within 120 min. No low-toxic CNO- intermediates were accumulated during the Electro-Fenton process. A new conversion mechanism was proposed that CN- was activated into electron-deficient cyanide radical (•CN) by •OH, and then the •CN intermediates reacted with •O2- via nucleophilic addition to quickly form NO3-, preventing the formation of CNO- and promoting the mineralization of cyanide. Furthermore, this new strategy was used to treat the actual cyanide residue eluent, achieving rapid recovery of irons and efficient mineralization of cyanides. In conclusion, this study proposes a new approach for the mineralization treatment of cyanide-containing wastewater.

Silver Single Atom in Carbon Nitride Catalyst for Highly Efficient Photocatalytic Hydrogen Evolution.

Single atom catalysts (SACs) with the maximized metal atom efficiency have sparked great attention. However, it is challenging to obtain SACs with high metal loading, high catalytic activity, and good stability. Herein, we demonstrate a new strategy to develop a highly active and stable Ag single atom in carbon nitride (Ag-N2 C2 /CN) catalyst with a unique coordination. The Ag atomic dispersion and Ag-N2 C2 configuration have been identified by aberration-correction high-angle-annular-dark-field scanning transmission electron microscopy (AC-HAADF-STEM) and extended X-ray absorption. Experiments and DFT calculations further verify that Ag-N2 C2 can reduce the H2 evolution barrier, expand the light absorption range, and improve the charge transfer of CN. As a result, the Ag-N2 C2 /CN catalyst exhibits much better H2 evolution activity than the N-coordinated Ag single atom in CN (Ag-N4 /CN), and is even superior to the Pt nanoparticle-loaded CN (PtNP /CN). This work provides a new idea for the design and synthesis of SACs with novel configurations and excellent catalytic activity and durability.

[Comparisons of sulfur contents and isotopes between mosses and surface soils in Jiangxi Province].

In order to study the influence of atmospheric sulfur on soil sulfur, the forest surface soil samples and moss samples were collected in north areas of Jiangxi province. Contents and isotopes of sulfur in different forms (total sulfur, water-soluble sulfur, absorbed sulfur and organic sulfur) were determined. The average sulfur content of mosses was 0. 34% +/- 0. 20%. All of the delta34S values except at Fengcheng (-3. 31 per thousand) were positive, the average was 5.64 per thousand +/- 2. 23 per thousand. The average contents of soil total sulfur were between 189.0 mg.kg-1 and 793.5 mg.kg-1. The organic sulfur was the main sulfur form in surface soils and the contents of water-soluble sulfur were the lowest. The delta34S values of total sulfur were in the range of 4. 45 per thousand +/-10. 28 per thousand. The highest soil delta34S values were determined for organic sulfur and the delta34S values of water-soluble and absorbed sulfur were similar. The contents of soil total sulfur were much lower than those of the mosses. Except for organic sulfur (R = 0. 50, P >0. 05) , the delta34S values of total sulfur, water-soluble sulfur and absorbed sulfur were all significantly correlated with those of moss sulfur (R >0.7, P <0. 01). These results indicated that atmospheric sulfur directly affected the total sulfur, water-soluble sulfur and absorbed sulfur, but not the organic sulfur.

[Study on modes of occurrence of bromine in coals using sequential chemical extraction procedure].

Modes of occurrence of bromine in eight coals from Sichuan and Chongqing were studied using inductively coupled plasma spectrometry and sequential chemical extraction. The results showed that the bromine mainly occur the water-soluble, ion exchangeable, carbonate, Fe-Mn oxides and organic fraction in these coals, which average total extraction rate was 88.2%. In bituminous coal and anthracite, the mean relative amount was 22.3% and 20.0% for organic bromine, 14.0% and 19.2% for the bromine of carbonate bound and almost equal for the bromine from water soluble and Fe-Mn oxidizes. The ion exchangeable bromine may be mainly adsorbed to organic matter in these coals. The relative amount of bromine in various modes of occurrence may not be very closely related to its sedimentary environment during the formation of coal. Bromine in coals from Sichuan and Chongqing should be paid more attention because its potential leachable rate was 36.62% - 86.80% and potential leachable content was 7.092- 20.10 microg/g.

[Nitrogen concentrations and stable isotope in epilithic mosses to investigate atmospheric N deposition and N sources in Jiangxi Province].

Atmospheric N deposition and N sources in Jiangxi Province were investigated on the basis of the nitrogen concentrations and nitrogen isotope in epilithic mosses which collected from 11 cities of the province during 2009-2010. Mean nitrogen concentrations ranged from 2.46% to 3.48% and showed a significant regional difference. The highest was found in the northwestern of the province and the lowest in the southeastern, reflecting that the level of the atmospheric N deposition gradually decreased from the north to the south in the province. The higher N concentrations in urban mosses than in suburban mosses indicated that the urban areas received higher rates of nitrogen deposition than suburbs areas. Mosses 15N values varied from (-9.74 +/- 0.25) per thousand to (-1.96 +/- 1.30) per thousand. More negative delta15N values of urban mosses (-5.51 per thousand-9.74 per thousand) indicated that more NH3 was released from excretory wastes and sewage, while less negative delta15N values of suburban mosses (-4.81 per thousand-1.96 per thousand) suggested an important contribution from agricultural NH3 emission due to intensive fertilizer application. This research provides basic information for further study on the ecological and environmental effects of atmospheric N deposition.

[Content and distribution of fluorine in Chinese coals].

Nationwide sampling program is designed according to the resources distribution and coal-forming periods as well as coal rank and yield of coal in China, and 305 coal samples were collected from 26 provinces, municipalities and autonomous regions. Fluorine in coal is determined by pyrohydrolysis / fluoride-ion selective electrode method. Fluorine in coals is mainly of an inorganic nature. Coal rank has no effect on fluorine content. The influence of a factor, such as geological age, on fluorine contents might be concealed by other factors, more research should be done to discern it. The distribution of fluorine in each province, municipality and autonomous region's coals is studied, and the fluorine source in coal-burning endemic fluorosis areas should be estimated over again. The contents of fluorine in Chinese coals show logarithm normal distribution, and 90% of values ranged from 47mg/kg to 347mg/kg, the average fluorine content in Chinese coals was designated as the geometric mean, 136mg/kg. Fluorine in Chinese coals is within the world coal's range.