Recovery of High Purity Y2O3 by Solvent Extraction Route Using Organo-Phosphorus Extractants

A rare earth concentrate assaying about 60% Y₂O₃, is generally obtained directly from Y rich minerals like xenotime or from monazite after preliminary fractionation of rare earths chloride as is practised currently at Indian Rare Earths Ltd.. Alwaye. Using this intermediate concentrate. SX process has been developed in our laboratory to purify Y (>99.9%) in presence of NH₄SCN. The process parameters for DEHPA and PC 88A systems have been optimised using a computer program in BASIC. The DEHPA flowsheet has been tested at bench-scale to produce several kilograms of 93% Y₂O₃. During these trials certain problems were faced due to high acidities. With PC 88A there were no problems and the flowsheet based on the solvent was confirmed at pilot-plant level. The solution containing 93% pure Y₂O₃, is purified further by another cycle of SX with 50% TBP in kerosene in presence of 1.0 M NH₄ SCN. The impurities are extracted leaving >99.9% pure Y₂O₃ in the aqueous phase. The process parameters optimised for obtaining >90% recovery of Y₂O₃ are described.     

EFFECT OF HOMOGENIZATION PRESSURE ON CONSISTENCY OF TOMATO JUICE 1

Pressurized homogenization of tomato juice at room temperature (28C) leads to an increased consistency and reduced serum separation in the juice. Percentage increase in consistency (as measured by Libby's tube) of hot processed juice from different cultivars ranged from 95 ± 3 to 282 ± 13 s. The magnitudes of change in consistency and serum spearation of cold processed juice due to homogenization were smaller than those for hot processed juice. Increases in consistency of cold processed juice ranged from 42 ± 4 to 213 ± 10 s. Consistency in all the samples increased with increasing pressure of homogenization up to a pressure of 3000 psi, above which it became constant. Homogenization of juice at higher temperature resulted in a very small increase in consistency. However, the magnitude of increase in consistency decreased with increasing temperature. Serum separation slightly increased at higher pressure of homogenization, after reaching a minimum with increasing pressure initially. In general, the juice with higher initial efflux and serum viscosities showed a larger increase in consistency and greater reduction in serum separation.     

EFFECT of WATER ACTIVITY ON VITAMIN A DEGRADATION IN WHEAT FLOUR (ATTA)

ABSTRACT. The effect of water activity (a_w) on the stability of vitamin A palmitate adsorbed onto wheat flour, starch, gluten, enzyme inactivated wheat flour and micro-crystalline cellulose was investigated. In wheat flour the rate of vitamin A degradation was lowest at 0.0 a_w. In gluten, starch and enzyme inactivated wheat flour, the rate was highest at 0.0 a_w and decreased with rise in a_w. the rate of lipid oxidation in wheat flour was lowest at 0.0 a_w whereas in enzyme inactivated wheat flour it was highest at 0.0 a_w and decreased with rise in a_w. In micro-crystalline cellulose system vitamin A degradation was least at 0.33 a_w and the rate of degradation increased both below and above this a_w. Among the wheat flour constituents, gluten provided better protection to vitamin A than starch. the role of lipoxygenase enzyme in accelerating the rate of degradation of vitamin A in wheat flour at higher a_w has been suggested.     

Radiolytic Degradation of Sorbic Acid in Isolated Systems

Effect of Co⁶⁰γ-irradiation on stability of sorbic acid (SA) in solutions, dough and chapaties has been investigated. SA was highly susceptible to radiolytic degradation in aqueous systems. Rate of degradation decreased with rise in pH. Sugars, hydrocolloids except pectin, citric acid, lactic acid, malic acid, arginine and threonine, catalysed degradation while oxalic acid, maleic acid, Cu²⁺, nitrite, nitrate and phthalate had protective effects. SA was more stable in alcohols and vegetable oils than in aqueous solutions. In wheat flour radiolytic degradation of SA was less at lower moisture. Relatively SA was more stable in chapaties than in dough. Gelatinization and addition of oil in dough reduced degradation of SA.     

Separation and Recovery of Copper,Nickel and Cobalt from the Copper Converter Slag by Solvent Extraction

An attempt has been made to develop a simple SX flowsheet to recover Ni, Cu and Co separately using alkyl phosphonic acid PC 88A diluted with kerosene. Process parameters such as phase ratio. pH of the feed solution and number of stages for extraction, scrubbing and stripping have been optimised. A computer program in FORTRAN has been developed to determine the process parameters for producing pure solutions of Ni. Cu and Co simultaneously in a counter-current set up. Conventional approach of separating individual metals in the order of their extraction affinities has also been studied. Both the processes have been found to yield Co, Cu and Ni sulphate solutions of purities required for downstream metal winning steps. This paper presents the salient data collected along with the optimised flowsheets.     

Monte Carlo simulation for reliability evaluation of complex systems

A complex system of s-dependent and s-independent units is considered in this paper for system reliability evaluation. It is also assumed that failure of any unit in the dependent set increases the failure probabilities of the remainder in the set. A general ease of partial redundant subsystems is considered. A computational algorithm to compute effective failure rates of the remaining components which fail sequentially, is explained for programme implementation. Fault-tree logic for the system failure is used as one of the subprogrammes. The advantage of this approach is that it can be used for a large complex system without any difficulty, besides many advantages normally associated with the fault-tree technique.     

Bromine pretreated chitosan for adsorption of lead (II) from water

Pollution by heavy metals like lead (II) is responsible for health hazards and environmental degradation. Adsorption is a prevalent method applied for removal of heavy metal pollutants from water. This study explored adsorption performances of 30% bromine pretreated chitosan for lead (II) abatement from water. Bromine pretreatment alters porosity and specific surface area of chitosan by means of physicochemical interaction with cationic sites of chitosan skeleton, besides imparting anionic alteration at amino linkages of chitosan, to remove lead (II) by chemical interactions on superfluous active sites as characterized by FTIR, SEM, DTA and elemental analysis. Lead adsorptions were studied in batch mode by varying parameters viz. pH, bromine loading, sorbent dosage, initial lead concentration, contact time and temperature. The adsorption equilibrium data was well fitted to Freundlich isotherm and maximum sorption capacity of 30% bromine pretreated chitosan sorbent was 1·755 g/kg with 85–90% lead removal efficiency. Though cost and applicability of sorbent is unproven, yet contrast to raw chitosan derivatives, activated carbons and some resins, 30% bromine pretreated chitosan endow benign and efficient lead abatement technique.     

Tomato Product Quality from Transgenic Fruits with Reduced Pectin Methylesterase

Juice from transgenic tomato (Lycopersicon esculentum cv Rutgers) fruits with reduced levels of pectin methylesterase (PME) activity due to the expression of a PME antisense gene exhibited improvement in quality. The percentage increase in juice from transgenic fruits over that of juice from wild type Rutgers ranged between 5.1–5.3 for total solids, 3.8–6.1 for soluble solids, 70–80 for efflux viscosity, 180–220 for serum viscosity and about 50 for precipitate weight ratio. Time of harvest had no effect on quality of juice. Ketchup prepared from transgenic fruit juice had a lower Bostwick value, reduced serum separation and high serum viscosity compared to ketchup from parental Rutgers.