Effect of Aerated Pore Distribution on Bubble Plume Movement in a Cylindrical Aerated Tank

Aeration is crucial for biological wastewater treatment process but energy intensive. Aerated pore distribution in an aeration tank can control oxygen transfer and energy consumption. Therefore, this study aimed at elucidating the fundamental flow structure of gas phase in bubble plumes in a cylindrical tank with different aerated pore distance (ranged from 0.03-0.09m). Both experiments and numerical simulation were used. PIV (Particle Image velocimetry) technology was used for getting bubble phase flow field. Bubble population behavior model (BPBM) coupled with computational fluid dynamics (CFD) was established for numerical simulation. Results showed that aeration distances greatly affected the movement of gas-phase. When the aeration distances were large or small, the attractive interaction generated by air columns in different aeration pore caused a turbulence of bubble plume. At the meanwhile, a large of bubbles separated from the main air columns, which resulted in an unsteady gas-phase structure. The structure of bubble plume was relatively stable with an aerator spacing of 0.0625m in this study, which was beneficial for the connection between gas-phase and liquid-phase.

4-[(1E)-({[(Benzylsulfanyl)methanethioyl]amino}imino)methyl]benzene-1,3-diol chloroform hemisolvate: crystal structure, Hirshfeld surface analysis and computational study

The title hydrazine carbodithioate chloroform hemisolvate, 2C15H14N2O2S2·CHCl3, comprises two independent hydrazine carbodithioate molecules, A and B, and a chloroform molecule; the latter is statistically disordered about its molecular threefold axis. The common features of the organic molecules include an almost planar, central CN2S2 chromophore [r.m.s. deviation = 0.0203 Å (A) and 0.0080 Å (B)], an E configuration about the imine bond and an intramolecular hydroxyl-O—H...N(imine) hydrogen bond. The major conformational difference between the molecules is seen in the relative dispositions of the phenyl rings as indicated by the values of the dihedral angles between the central plane and phenyl ring of 71.21 (6)° (A) and 54.73 (7)° (B). Finally, a difference is seen in the disposition of the outer hydroxyl-H atoms, having opposite relative orientations. In the calculated gas-phase structure, the entire molecule is planar with the exception of the perpendicular phenyl ring. In the molecular packing, the A and B molecules assemble into a two-molecule aggregate via N—H...S hydrogen bonds and eight-membered {...HNCS}2 synthons. The dimeric assemblies are connected into supramolecular chains via hydroxyl-O—H...O(hydroxyl) hydrogen bonds and these are linked into a double-chain through hydroxy-O—H...π(phenyl) interactions. The double-chains are connected into a three-dimensional architecture through phenyl-C—H...O(hydroxyl) and phenyl-C—H...π(phenyl) interactions. The overall assembly defines columns along the a-axis direction in which reside the chloroform molecules, which are stabilized by chloroform–methine-C—H...S(thione) and phenyl-C—H...Cl contacts. The analysis of the calculated Hirshfeld surfaces, non-covalent interaction plots and interaction energies confirm the importance of the above-mentioned interactions, but also of cooperative, non-standard interactions such as π(benzene)...π(hydrogen-bond-mediated-ring) contacts.

Probing the gas-phase structure of charge-tagged intermediates of a proline catalyzed aldol reaction – vibrational spectroscopy distinguishes oxazolidinone from enamine species

Charge-tagging enables the detection of reaction intermediates which are probed by IRMPD spectroscopy in combination with theory.