Adiabatic gas absorption in packed columns with large thermal effects

The performance of packed bed adiabatic gas absorbers has been analyzed using the enthalpy and material balance equations incorporating a new parameter, f_r, defined as the fraction of the heat of absorption that is accounted for in the gas stream. An experimental programme to evaluate f_r was carried out and the data correlated. It was found that f_r was dependent on the thermo-physical properties and the hydrodynamic conditions. It is postulated that the mechanism by which this heat transfer occurs is by turbulence at the interface and by entrainment.     

Toxic organic wastewater treatment through solid phase transformation with re-use potential

A novel treatment of wastewater generated in the production of dinitrobenzene was examined. The method involves solid phase transformation of the wastewater by slaking with lime, followed by removal of the organics contained in the lime in a muffle furnace. The regenerated lime may be re-used, e.g., for the neutralization of acidic wastewaters resulting from the manufacture of m-aminophenol. A flowsheet for the integrated treatment of dinitrobenzene and m-aminophenol plant wastewaters is proposed.     

Process standardization for optimal virus recovery and removal of substrate DNA and bovine serum proteins in Vero cell-derived rabies vaccine

Purification of a rabies vaccine by a single zonal centrifugation run was replaced by two runs with optimal standardization of the sucrose density gradient. As a result, significant reductions in the levels of substrate DNA and bovine serum protein in the Vero cell-derived human rabies vaccine were achieved. Following many trials, for the first run, loading of the 3.2-l capacity K-3 rotor with 1800 ml of 60% sucrose solution and 1400 ml of vaccine PBS buffer solution gave a satisfactory linear gradient. However, after the first run, the substrate DNA and bovine serum contents exceeded the required levels. After protamine sulphate and Tween-80 treatment of the concentrated inactivated material, a second run using the same procedure as in the first run was tried. However, these purification procedures resulted in low virus recovery. To achieve optimal virus recovery, and removal of substrate DNA and bovine serum protein, the peak fractions from the first run as indicated by the haemagglutination, sucrose concentration, and optical density values were pooled and the sucrose concentration of the pooled fractions was increased to 60%. A second (flotation) run was then carried out. Using this method, the virus recovery rate was more than 95% that of the first run, and the levels of cellular DNA and bovine serum protein were well within the acceptable limits of less than 100 pg/dose and one part per million, respectively. The substrate DNA was quantified by both radioactive labeling and non-radioactive biotin labeling methods. For the quantification of calf serum protein, a counter-immunoelectrophoresis method was developed and effectively applied. A potency assay was performed using the National Institutes of Health (NIH) and well-standardized in vitro single radial immuno diffusion (SRD) methods. Finally, an immunogenicity study was conducted with human volunteers and the results were confirmed by a rapid fluorescent focus inhibition test (RFFIT).     

Enhanced heterogeneous ferrioxalate photo-fenton degradation of reactive orange 4 by solar light

A combined homogeneous and heterogeneous photocatalytic decolourisation and degradation of a chlorotriazine Reactive azo dye Reactive Orange 4 (RO4) have been carried out using ferrous sulphate/ ferrioxalate with H₂O₂ and TiO₂-P25 particles. Solar/ferrous/H₂O₂/TiO₂-P25 and solar/ferrioxalate/H₂O₂/TiO₂-P25 processes are found to be more efficient than the individual photo-Fenton and solar/TiO₂-P25 processes. A comparison of these two processes with UV/ferrous/H₂O₂/TiO₂-P25 and UV/ferrioxalate/H₂O₂/TiO₂-P25 reveals that ferrioxalate is more efficient in solar light whereas ferrous ion is more efficient in UV light. The experimental parameters such as pH, initial H₂O₂, Fe²⁺, ferrioxalate and TiO₂-P25 concentration strongly influenced the dye removal rate in solar processes. The optimum operating conditions of these two combined processes are reported.