Performance evaluation of zero-valent iron nanoparticles (NZVI) for high-concentration H2S removal from biogas at different temperatures.

The removal performance of high-concentration H2S (ca. 10 000 ppm) from simulated biogas by zero-valent iron nanoparticles (NZVI), with the majority of the particles in the size range of 60-150 nm, at different reaction temperatures (room temperature, 100 °C, 200 °C and 250 °C) were evaluated using a custom-designed quartz fixed-bed reactor. The results showed that the H2S removal capacities of NZVI were quite limited at room temperature and 100 °C, being 12.56 and 14.77 mg H2S gNZVI-1, respectively. However, these values increased significantly to 391.02 (200 °C) and 488.95 (250 °C) mg H2S gNZVI-1. Scanning electron microscopy analysis showed that the products of the NZVI-H2S reaction aggregated to form irregular polygonal-shaped structures. The main X-ray diffraction pattern peaks of the product matched well with troilite, and no pyrite was observed. The deconvolution of the X-ray photoelectron spectrometry peaks showed the presence of monosulphide (S2-) and disulphide (S2 2-) in the product, in which 36% of the sulphur existed as monosulphide and 64% as disulphide. It is proposed that the effective removal of hydrogen sulphide by NZVI at elevated temperatures can be attributed to the combination of nano-constituents, oxide shell and underlying Fe core to produce FeS similar to troilite and amorphous FeS2.

A Novel Insecticidal Peptide SLP1 Produced by Streptomyces laindensis H008 against Lipaphis erysimi.

Aphids are major insect pests for crops, causing damage by direct feeding and transmission of plant diseases. This paper was completed to discover and characterize a novel insecticidal metabolite against aphids from soil actinobacteria. An insecticidal activity assay was used to screen 180 bacterial strains from soil samples against mustard aphid, Lipaphis erysimi. The bacterial strain H008 showed the strongest activity, and it was identified by the phylogenetic analysis of the 16S rRNA gene and physiological traits as a novel species of genus Streptomyces (named S. laindensis H008). With the bioassay-guided method, the insecticidal extract from S. laindensis H008 was subjected to chromatographic separations. Finally, a novel insecticidal peptide was purified from Streptomyces laindensis H008 against L. erysimi, and it was determined to be S-E-P-A-Q-I-V-I-V-D-G-V-D-Y-W by TOF-MS and amino acid analysis.