Akira Suganuma

The effect of cationic polymer on the settling characteristics of activated sludge

Abstract The physical properties of activated sludge flocculated by cationic polymer (polyethyleneimine) were investigated. It was found that the hindered settling rate, the typical settling rate of a typical aggregate and the sediment volume increased with the amount of cationic flocculant due to an increase in aggregate size. But the surplus addition of flocculant caused the deflocculation of aggregates and decreased the hindered settling rate and the sediment volume. It was confirmed by measuring the buoyant density of the individual flocculated aggregate that the flocculant made the aggregate more compact than a natural aggregate of activated sludge. The mean buoyant density of the flocculated aggregates was calculated from a hydrodynamic volume coefficient which was obtained in the hindered settling experiments. The relationship between the calculated mean buoyant density and the size of a typical aggregate which had the typical settling rate at the various concentrations of flocculant was roughly similar to the relationship between the buoyant density of an individual aggregate and the aggregate size when the concentration of flocculant was 3 p.p.m. In spite of an increase in buoyant density in comparison with a natural aggregate which had the same size as the flocculated one, the settling rate of a flocculated aggregate did not increase so much as was expected by applying the settling rate equation for a rigid body. This result was explained by the effect of permeability on the settling rate.

Solubilization of Taiheiyo coal under mild conditions without gaseous hydrogen: catalysis by trifluoromethanesulfonic acid

Abstract Trifluoromethanesulfonic acid (TFMS) was found to convert coal almost completely to pyridine-solubles in the presence of isopentane at 150°C in 3 h under autogenous pressure of 6.0–6.8 MPa. The chemical structure of the benzene-soluble and THF-insoluble-pyridine-soluble fractions varied with the acid concentration. Lower acid concentrations provided high aromaticity and rich H ar and H α , while higher acid concentrations gave higher H β and H γ . The solubilized coal fractions bore many oxygen functional groups in spite of depolymerization. The ether bonds remained in the pyridine-insoluble fraction, resulting in a high molecular weight. Intermolecular hydrogen bonding of oxygen functional groups appears to be another cause of limited solubility of this fraction.

Solubilization of lignite with superacid (trifluoromethanesulfonic acid)/isopentane at the mild conditions

Abstract Trifluoromethanesulfonic acid (TFMS) was found to solubilize lignite and subbituminous coal in the presence of isopentane at temperature as low as 150°C for three hours under autogeneous pressure of 6.1–6.9 MPa without hydrogen. Yallourn coal gave 63 wt% pyridine soluble fraction after reaction and required more TFMS to achieve the maximum solubility, but the treated Taiheiyo coal could be solubilized in pyridine to the extent of 90% by the same reaction with TFMS. Acid-catalyzed depolymerization with TFMS would be inadequate, because the lignite has many oxygen containing functional groups. The average molecular weight of benzene soluble and THF soluble fraction from the treated Yallourn coal decreased, and their aromaticity increased with the increase of TFMS concentration. In contrast, average molecular weight of soluble fraction from the treated Taiheiyo coal was unchanged, and their aromaticity decreased with the increase of TFMS concentration. It is suggested that TFMS plays an important role in depolymerization of the coal molecules for Yallourn coal solubilization, and accelerates alkylation and hydrogenation in the Taiheiyo coal solubilization. Oxygen functional groups would lower the activity of TFMS as acid catalyst by interaction, leading to the formation of water from the cleavage of aliphatic ether groups and the dehydration of phenoxy OH groups.

Behaviour of sulfur in high-sulfur coal in a superacidic medium without gaseous hydrogen

A Bronsted superacid, trifluoromethanesulfonic acid (TFMS), was found to desulfurize a lignite in the presence of a hydrocarbon without gaseous hydrogen at 150–200°C under autogenous pressure of 2.6–6.6 MPa. Removal of sulfur from the coal depended on the solvent, TFMS concentration and reaction temperature. TFMS alone without solvent removed only 5.3% of sulfur as H2S, increasing the thiophenic sulfur content of the coal. In contrast, TFMS in toluene achieved 35.4–41.3% desulfurization, mainly from sulfides. Toluene in the presence of TFMS behaves as hydrogen donor to eliminate sulfidic sulfur as H2S, while preventing acidic cyclization of sulfides to thiophenes.

Control of the bulk flow of granular materials by an aeration technique

Abstract Discharge of granular materials through a standpipe against an imposed overall gas pressure difference has been studied experimentally. The particles were transported from a low pressure region to a high pressure region and discharged through an orifice by aeration. With air introduced to aerate the particles, particle flow against the pressure difference was found to be more stable than without aeration. The particles can be discharged through the orifice stably even when the overall pressure difference in the pipe is just below that for fluidization. The mass flow rate of particles is correlated to the pressure difference across the discharging orifice and to its diameter. Effects of aeration on discharging rate were examined. An experimental equation which correlates the particle flow rate to the pressure difference across the orifice was obtained.

Solubilization and desulphurization of high sulphur coal under mild condition with trifluoromethane sulphonic acid

Publisher Summary This chapter describes the activity of trifluoromethane sulphonic acid (TFMS) examined on the coal desulfursulfursulfurization as well as solubilization. Desulfursulfursulfurization of high sulfur coal is studied in the acid-catalyzed depolymerization reaction by the aid of super acid, TFMS, without gaseous hydrogen at milder conditions. TFMS is found to desulfursulfursulfurize coal in the presence of hydrocarbon without gaseous hydrogen at 150–200° C for three hours under autogeneous pressure of 2.6–6.6 MPa. Toluene provided 48.7% desulfursulfursulfurization and higher solubility about 86 wt% soluble in THF, 76 wt% soluble in benzene, and 50 wt% soluble in hexane. Sulfur in coal is released as hydrogen peroxide (H 2 S).