Speaker
Description
Natural radioactivity is extensively existing in the earth’s natural environment because it is composed of the cosmogonic and primordial radionuclides, hence it is commonly occurring in different ecological, geological as well as environmental formations like, rocks, soils, sand, plants, water, and air. There are several other industries such as Coal fired power plants, Phosphate fertilizer production plants and Granite cutting & polishing Industries etc. which release alpha emitting natural radionuclides like 238U, 232Th and 222Rn into the environment during production, manufacturing and discharge processes which has been steadily increased therefore, it is of vital interest to monitor the alpha radioactivity in the air, solid and liquid waste emanating from these industries. Solid State Nuclear Track Detection (SSNTD) is one of the most convenient analytical technique to measure low level alpha radioactivity due to its numerous advantages such as simplicity, high sensitivity, and capacity to store permanent records. In the present investigation we have standersized CR-39 detector using thorium nitrate and uranyl nitrate salt solution and we have optimesed different parameters like Concentration range (5- 1000µg/L) Etching time (1-8 H) Exposure time (1-24 H) Normality of etchant (2-6M) Temperature (50-75˚C) and Amount of TEAB added to NaOH (1-10%). Differnet effluent samples were collected from the discharge point source of selected industries. An advanced functional material such as organic polymeric chemically known as Allyl Diglycol polyarbonate CR-39 detector pieces of thickness 700 micron and size of (1.5 cm × 1.5 cm) were then immersed into effluents for a different period to study alpha track detection. Therefore, these tracks have been extensively investigated as shown in Figure 1 applying new chemical etching method of comprising a mixture of 5% Tetraethyl ammonium bromide (TEAB) with 6M NaOH (w/w) at optimized temperature of 60˚C. The observations of these detector pieces were done under optical microscope attached with digital camera in addition of Magvision software at the higher magnification, spinning disc confocal microscope Scanning electron microscopy & Atomic Force Microscopy to study the morphology of alpha tracks in CR-39 detector. The total number of tracks were counted, and highest track density and average track diameter at different exposure times for all samples was measured. Low level concentrations of 238U & 232Th (µg/L) from these effluent samples taken along from these industries were measured by Inductively Coupled Plasma Mass Spectrometer. The introduction of Tetraethyl ammonium bromide with NaOH as a new chemical etchant has provided better enhancement in formation and revelation of alpha tracks in very less etching time. The output of the developed etching technique appears extremely better for the usual track appearance, track density, and track diameter profile. The present work offers a novel approach to detect alpha track detection on CR-39 and low-level environmental alpha radioactivity from industrial effluent samples.
Key Words: CR-39, TEAB, Alpha Tracks, AFM, ICPMS,
