Polymeric sorbents and biocomposites a b s t r a c t Various sorbents have been used to remove arsenic from contaminated water which is one of the most toxic elements for mankind. In this review, concentration has been focused on the removal of arsenic from aqueous medium using natural, non-toxic, biodegradable and eco-friendly polymeric materials. Therefore, chitosan has been selected one of the most appropriate biopolymer to remove heavy metals form contaminated water particularly arsenic. Therefore, chitosan grafting, blending, doping and biocomposite formulations with polymeric and/or activated inorganic materials have gained much attention. This review provides the relevant literature on the applications of polymeric biocomposites for removal of arsenic from aqueous medium. However, the literature survey reveals that very limited attention has been focused on the applications of biocomposites for the removal of arsenic in the past. The sorption capacities of sorbents and LD 50 of the arsenic compounds have been compiled.

NaISoil Radioactivity a b s t r a c t Humans are always exposed during their lives to ionizing radiation arising outside and within the earth. The exposure to these radiation occurs from natural sources such as radioactive elements in rocks and soil, internal exposure form radioactive elements through water, food and air and cosmic rays entering from outer space to earth's atmosphere. About 87% of the radiation dose received by human beings is due to natural radiation, it is essential to assess the radiation doses in order to control possible health effects from such natural sources. In this regard, a number of articles have been appeared for Malaysia in international research journals, which have been reviewed and complied in this article. Most of these articles are about the measurement of activity concentrations of primordial ( 238 U, 232 Th, 226 Ra and 40 K) and anthropogenic ( 137 Cs) radionuclide's and gamma dose rate in environmental samples using HPGe and NaI (Tl) survey meter.

Banana trunk fibers (BTF)-reinforced chitosan (BTF-i-CTS) biocomposite film was prepared and characterized by means of Fourier-transform infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy. Characterization of the starting materials and the biocomposite indicated that BTF are widely immobilized in chitosan (CTS) by physical means. The water uptake results of BTF-i-CTS indicated a maximum water uptake of 338.23% with an equilibrium time of 72 h. The starting materials and BTF-i-CTS in comparison with chitin and activated carbon (AC) were used for the removal of Cr 6+ . The effect of pH, contact time and initial concentration was investigated. Contact time of 120 min and pH of ~ 7.00 were selected for the removal of Cr 6+ , at ambient temperature (27 ± 1 °C). The percentage removal of Cr 6+ at pH ~ 7.00 and initial concentration of 50 mg/L using BTF-i-CTS, CTS, BTF, chitin and AC was observed 97. 79, 97.78, 25.79, 36.80 and 23.78%, respectively. The data best-fitted pseudo-second-order kinetic and Freundlich isotherm model indicated that chemisorption is the likely factor for the removal of Cr 6+ .

Radon concentration, exhalation rate, radium activity and annual effective dose have been measured from baked and unbaked bricks and cement samples commonly used as construction material in the dwellings of Dera Ismail Khan City, Pakistan. CR-39 based NRPB radon dosimeters and RAD7 have been used as passive and active devises. The values of radon concentration for baked, unbaked bricks and cements obtained from passive and active techniques were found in good agreement. Average values of radon exhalation rates in baked, unbaked bricks and cement were found (1.202±0.212) Bq m −2 h −1 , (1.419±0.230) Bq m −2 h −1 and (0.386±0.117) Bq m −2 h −1 and their corresponding average radium activity and annual effective dose were found (0.956±0.169) Bq/kg, (1.13±0.184) Bq/kg, (0.323±0.098) Bq/kg and (33.96±5.99) µSv y −1 , (40.3±6.51) µSv y −1 and (10.94±3.28) µSv y −1 , respectively. Radon concentration, exhalation rate and their corresponding radium activity and annual effective dose were found higher in unbaked bricks as compared to baked bricks and cement but overall values of radon exhalation rate, annual effective dose and radium activity were found well below the world average values of 57.600 Bq m −2 h −1 , 1100 µSv y −1 and 370 Bq/kg, respectively.

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