Distribution of naturally occurring radionuclides (U, Th) in Timahdit black shale (Morocco)

Attention has been focused recently on the use of Moroccan black oil shale as the raw material for production of a new type of adsorbent and its application to U and Th removal from contaminated wastewaters. The purpose of the present work is to provide a better understanding of the composition and structure of this shale and to determine its natural content in uranium and thorium. A black shale collected from Timahdit (Morocco) was analyzed by powder X-ray diffraction and SEM techniques. It was found that calcite, dolomite, quartz and clays constitute the main composition of the inorganic matrix. Pyrite crystals are also present. A selective leaching procedure, followed by radiochemical purification and α-counting, was performed to assess the distribution of naturally occurring radionuclides. Leaching results indicate that 238U, 235U, 234U, 232Th, 230Th and 228Th have multiple modes of occurrence in the shale. U is interpreted to have been concentrated under anaerobic conditions. An integrated isotopic approach showed the preferential mobilization of uranium carried by humic acids to carbonate and apatite phases. Th is partitioned between silicate minerals and pyrite

Kontribusi Kecepatan Reaksi dan Kekuatan Otot Lengan terhadap Kemampuan Pukulan Backhand Tenis Lapangan

This study aims to see how much the contribution of reaction speed and arm muscle strength to the backhand ability of students at the Faculty of Sport Science, Padang State University.This research method is correlation. The population in this study were students who took part in the tennis court classes and only 20 male students were sampled, using a purposive sampling technique. This research was conducted on September 24, 2019, taking place in the indoor tennis court of the Faculty of Sport Science, Padang State University. Reaction velocity data were taken with the whole body reaction test, arm muscle strength with a two hand medicine ball put test, and the ability to test the ability of backhand tennis court. The data analysis technique of this study used the requirements analysis test technique, namely the normality test and continued with product moment correlation analysis, multiple correlation then continued with the regression test.The results of data analysis show that: (1). There is a contribution between reaction speed and backhand capability, which is 16%; (2) there is a contribution between the strength of the arm muscles towards the ability to backhand, which is 30%; (3) there is a contribution between reaction speed and arm muscle strength together to the backhand ability, which is 36%

Production of a new adsorbent from Moroccan oil shale by chemical activation and its adsorption characteristics for U and Th bearing species

New adsorbents were prepared from Moroccan oil shale of Tarfaya (layer R3) by chemical activation with sulphuric acid diluted at 80%. The influence of activation temperature, atmosphere gas, holding time in oven and weight ratio of sulphuric acid to precursor was investigated by determination of yield of adsorbents and adsorption capacity of methylene blue. The best adsorbent properties were found for a particular combination of the chosen parameters: temperature and time of activation respectively equal to 250$^{\circ}$C and 2 hours, the gas vector being nitrogen (N$_{2})$. The adsorption capacity for methylene blue and specific surface (S$_{\rm BET})$ of the new adsorbent were equal to 300 mg/g and 270 m$^{2}$/g respectively. The batch mode experiment was used to explore the feasibility of this adsorbent for removal of radionuclides (U and Th) from aqueous solution. Applicability of the adsorbent was examined for synthetic solution prepared from hydrated uranyl nitrate (UO$_{2}$(NO$_{3})_{2}$.6H$_{2}$O) and hydrated thorium nitrate (Th(NO$_{3})_{4}$.5H$_{2}$O). The parameters of adsorption for the two radioelements were determined by application of the Langmuir, Freundlich and Elovich models

Natural radioactivity in phosphates, phosphogypsum and natural waters in Morocco

International audienceThe contents of natural radionuclides (uranium. actinium and thorium series) were measured in sedimentary phosphate rock samples using high-resolution gamma spectrometry. Data obtained for uranium content (ppm) were compared with the results obtained by a method based on the measurements using solid-state nuclear track detectors (SSNTD) in the same samples. The potential leaching of radionuclides from sedimentary phosphate rock during the industrial production of the phosphoric acid was studied. The process of leaching of the radioisotopes from phosphogypsum was discussed. A method for the direct alpha counting of Ra-226 thin source. elaborated by the deposition of Ra from aqueous solutions on manganese oxides film deposited on polyvinyl support, have been developed and applied for the determination of Ra-226 in natural water samples. The results show that only the water sample from the mine area reveals the presence of Ra-226 at a level of about 0.2 Bql(-1) (C) 2001 Elsevier Science Ltd. All rights reserved