Efficient removal of metal ions from aqueous solutions using MoS2 functionalized chitosan Schiff base incorporated with Fe3O4 nanoparticle.

In the present work a novel pyrazole based chitosan Schiff base material was prepared using 5-azido-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde and functionalized using Fe3O4-MoS2, where the nanoparticles get embedded within the gel matrix. The composite material was characterized using various techniques such as XRD, SEM, FTIR, EDS and TGA. The adsorbent material was analysed for the adsorptive take up process from the aqueous solutions of metal ion concentration ranging 20-100 mgL-1. The maximum adsorption capacity obtained for the material was 200.00 and 125.00 mg/g for Cr(VI) and Cu(II) respectively. Adsorptive mechanism was found to have pseudo second order kinetics and the adsorption isotherm followed Langmuir adsorption model following the monolayer adsorptive process. Further the evaluated thermodynamic parameter showed the adsorption process to be spontaneous and endothermic in nature. Reusability of the composite material was achieved using suitable stripping solutions.

Seasonal variation of indoor radon, thoron and their progeny in Belagavi district of Karnataka, India.

Systematic investigations on the seasonal variation of indoor radon, thoron and their progeny levels have been carried out in Belagavi district of Karnataka, India. The radon and thoron levels were measured using LR-115 type II dosimeter in cups with single-entry pinhole. The measurements were carried out in all the four season, viz, monsoon, autumn, winter and summer, in selected houses of the region. The higher indoor radon levels were observed during autumn with an average concentration of 56.45 Bq m-3. The minimum in radon levels was observed in summer with an average concentration of 21.8 Bq m-3. The indoor thoron concentration was also maximum during autumn with an average value of 36.44 Bq m-3 and minimum in summer with an average value of 15.9 Bq m-3. The radon and thoron levels were also found to depend on the nature of walls and floorings of dwellings. The lung dose rate to the population due to radon ranged from 1.195 to 9.557 mSv year-1, with an average of 4.572 mSv year-1. Risk levels were found to be significant during autumn and winter due to the inhalation of indoor radon and thoron. The study forms the first comprehensive report on the indoor radon and thoron levels and the resulting population dose in the Belagavi region. The studies reveal that the major contributor to the population is radon and its progeny. However, a sizable dose also comes from indoor thoron and its progeny. The study emphasises the need to provide better ventilation system to future dwellings to reduce the risk from indoor radon and thoron.

Distribution of natural radionuclides and radon concentration in the riverine environs of Cauvery, South India.

Systematic studies were carried out to understand the distribution of natural radionuclides in sediments and radon in water in the riverine environs of Cauvery, one of the major rivers of South India. The activity of radionuclides in the sediment was measured by gamma ray spectrometry. The radon emanation from the sediment was measured by the sealed 'can technique' and the radon in the water was measured using the RAD-7 instrument. The mean values of 40 K, 226Ra, and 232Th in the sediment samples were found to be 297.3 ± 4.16 Bq kg-1, 75.1 ± 2.64 Bq kg-1, and 85.5 ± 2.62 Bq kg-1, respectively. The mean activity of radon, radon exhalation rate, and radium content were found to be 135.68 Bq m-3, 327.1 mBq m-1 h-1, and 133.03 mBq kg-1, respectively. The radon in the water ranged from 0.19 kBq m-3 to 1.40 kBq m-3. The hyper pure germanium gamma spectroscopy measured via 226Ra activity and the radon activity measured by the passive can technique showed good correlation. The mean value of radon in the water was within the internationally recommended level. The sediment was considered safe for the purpose of construction, except for some extreme values, and the water was deemed safe for drinking.

DISTRIBUTION OF 210PO IN HEMAVATHI RIVERINE ENVIRONMENT.

In the present investigation, the concentration of 210Po was measured in soil and sediment samples from riverine environment of Hemavathi river of south Karnataka. The 210Po in the samples was separated by radiochemical method, and the activity was counted using ZnS(Ag) alpha counter. Seasonal variation of 210Po was studied for soil and sediment samples. The mean activity of 210Po in monsoon was higher than that in pre-monsoon samples. The granulometric contents (sand, silt and clay), organic matter and pH contents were measured in soil, and sediment, respectively. The organic matter content and clay positively correlated with 210Po activity. There is a good correlation between activity concentration of 210Po and organic matter in both monsoon and pre-monsoon samples. Using the SPSS 22 statistical software, the median, skewness, kurtosis, variance and frequency distribution were calculated.

NATURAL RADIONUCLIDE LEVELS IN SEDIMENTS OF CAUVERY RIVERINE ENVIRONMENT.

The paper presents the systematic measurement of activity concentrations of 40K, 226Ra and 232Th in sediment sample of Cauvery river of Karnataka, South India. Activity was measured using HpGe gamma ray spectrometer, and the mean values of 40K, 226Ra and 232Th in the sediment samples were found to be 144.31, 32.05 and 61.70 Bq kg-1, respectively. To assess the radiological hazards in the samples, radium equivalent (Raeq), absorbed dose (D), annual effective equivalent dose (AEED), activity utilisation index (AUI) and annual gonadal dose equivalent (AGDE) values associated with the radionuclides were calculated and compared with international recommended values.

NATURAL RADIOACTIVITY IN SEDIMENTS AND RIVER BANK SOIL OF KALLADA RIVER OF KERALA, SOUTH INDIA AND ASSOCIATED RADIOLOGICAL RISK.

The paper presents the activity concentrations of 232Th, 226Ra and 40K in the sediments and river bank soil samples collected from the Kallada river environs of coastal Kerala. The radiological risks associated with these radionuclides were calculated. The samples were processed following standard procedure, and activity was counted using a high-efficiency 5″ × 5″ NaI (Tl) detector coupled to GSPEC gamma spectroscopy system. The mean values of measured activities of 232Th, 226Ra and 40K in soil samples were found to be 98.1 ± 0.4, 60.3 ± 1.1 and 343.4 ± 1.8 Bq kg-1, respectively, which results in an average absorbed dose rate of 103 nGy h-1 The corresponding values for sediment samples were found to be 88.0 ± 0.4, 48.6 ± 0.9 and 423.2 ± 2.0 Bq kg-1, respectively, with a resulting absorbed dose rate of 95 nGy h-1 Radium equivalent activity, annual effective dose equivalent, the external and internal hazard indices were determined and compared with recommended limits. The results of the work provide background data on natural radioactive isotopes, which are useful in the assessment of human radiation exposure from natural environment. The accumulation of information on natural radiation is of great value for radiation protection.