Search

Degradation of bromocresol green in alcohol-water solution using ozone micron sized bubbles is reported. A high speed impeller is used to generate micro bubbles of ozone in liquid while ozone is generated using a commercial ozone generator. A 3-level-3-factor Box–Behnken experimental design is used to statistically identify relative importance of the operating parameters studied namely impeller speed, initial concentration of dye and treatment time. Ozone dosage is kept fixed at 4 g/h. Impeller speed is found to be the most dominant factor according to Analysis of Variance (ANOVA) calculations. Kinetics for degradation of bromocresol green in solution is also reported. A second order kinetics is seen to fit the experimental (concentration–time) data, corresponding value of rate constant being 0.0153 L/mg-s. Based on the laboratory scale data a detailed techno-commercial analysis of a scaled up (75 kL/day) plant for ozone based degradation of bromocresol is presented. All relevant economic indicators pertaining to the scaled up plant are reported. A specific treatment cost of Rs. 100/m3 of treated water yields a return on investment (ROI) of 68.77 and discounted payback period of 5 years. [ABSTRACT FROM AUTHOR]

90Sr (T1/2 = 28 y) is always in equilibrium with 90Y in High Level Liquid waste (HLLW) and hence 90Sr is a suitable long lasting source of 90Y, if it is purified suitably for therapeutic applications. A combination of CMPO & TBP was found to be the most suitable solvent system for alpha activity removal. CMPO has high selectivity for alpha contaminants (Pu/Am) w.r.t. 90Sr. For regeneration of spent organic, 3 M Phosphoric acid was most suitable with the ability to strip back more than 98% of gross alpha activity in single contact and thus solvent system was qualified for recycling. [ABSTRACT FROM AUTHOR]

The effect of ball size and interstitial filling on the performance of dry ball mill grinding was investigated for a limestone-type brecciated uranium ore. The optimum grinding was obtained with the combination of different balls (12.7–37.5 mm) and interstitial filling of 50% (20% ball filling ratio at fixed material filling ratio = 4%). The net power consumption in a ball mill is proportional to the specific rate of breakage. A mathematical relation for the specific rate of breakage as a function of ball filling ratio was developed. The grinding process was modeled by the combined use of matrix and population balance model. The cumbersome method of mono-size fraction in the determination of the selection function was avoided, and instead, it was determined by the back-calculation method. The estimated parameters of the Austin selection function for a particular ball size (31.7 mm) were successfully applied in predicting the ground product size distribution (R2 > 0.95) for both a given feed size distribution and a given feed rate. [ABSTRACT FROM AUTHOR]

90Y, a beta emitting radionuclide (T1/2 ~ 64 h, Emax= 2.3 MeV), the daughter product of 90Sr is used for radio therapeutic applications. Non dispersive solvent extraction in hollow fibre membrane contactor (HFMC) with CMPO solvent studies were done to achieve the desired purification of 90Sr nitrate solution with respect to gross alpha activity. This purified solution is promising feed for 90Sr–90Y generator to achieve the clinical grade product of 90Y. In HFMC recirculations, around 99.97% alpha impurities were extracted in two recirculations from the feed solution with 0.2 M CMPO while only two recirculations were required with 0.4 M CMPO. A simplified mathematical model has also been developed to model the extraction of alpha impurities through the HFMC using CMPO as a solvent. [ABSTRACT FROM AUTHOR]