Conversion of Argan Nutshells into Novel Porous Carbons in the Scope of Circular Economy: Adsorption Performance of Emerging Contaminants

The present work proposes an experimental strategy to prepare argan nutshell-derived porous carbons using potassium hydroxide (KOH). Several experimental parameters of the activation process were evaluated (temperature, impregnation ratio, and activation time), and an optimized carbon (ACK) was obtained. The surface properties of the ACK sample were determined, and the porous carbon was applied as an adsorbent of diclofenac (DCF) and paroxetine (PARX). A commercial carbon (CC) was used as a benchmark. The ACK porous carbon presented a higher surface area and micropore volume (1624 m2 g−1 and 0.40 cm3 g−1, respectively) than CC carbon (1030 m2 g−1 and 0.30 cm3 g−1, respectively), but the maximum adsorption capacities of DCF (214–217 mg g−1) and PARX (260–275 mg g−1) were comparable among the two carbons. Besides π-π interactions, H-bonds with the electronegative atoms of the adsorbate molecules and the electropositive H of the oxygen functional groups were appointed as the most probable mechanisms for adsorption onto ACK porous carbon. The electrostatic attraction was also considered, particularly for DCF with CC carbon. The pore size might have also been critical, since CC carbon presented more supermicropores (0.7–2 nm), which are usually more favorable toward the adsorption of pharmaceutical molecules. The reusability of the ACK carbon was tested up to four cycles of adsorption–desorption by using ultrasonic washing with water. The results indicated that no more than one cycle of use of ACK should be performed

Studies on the separation of Uranium from Algerian yellow cake using different processes: impurities determination

Analysis of impurities in uranium materials is crucial for quality control or the purity required by standards in the nuclear industry. This study involves the analysis of impurities in a sample of uranium ore concentrate produced from Tahaggart ore. The instrumental techniques used for the analysis are highly sensitive and susceptible to much interference following the uranium spectrum. Different processes for separating uranium from impurities for comparison were used to quantify them. The uranium sample is an Algerian yellow cake that was digested in nitric acid, separated by solvent extraction using the TBP/CHCl3 system, by extraction chromatography method using tributyl phosphate (TBP) impregnated on the Amberlite XAD-7 resin and by precipitation of uranium with hydrogen peroxide. The raffinate from each process is then analyzed by flame atomic absorption spectroscopy and flame photometry. The concentration of uranium is determined by the Potassium Bichromate method in concentrated solutions and by the Arsenazo III method in raffinates and eluates. Uranium extraction yields are 99.65% using TBP-CHCl3 and exceed 99% using TBP-impregnated XAD-7 resin. The results of the analysis of impurities in Algerian yellow cake after the separation of uranium using different processes show that the contents meet the ASTM C967-13 standard for the elements analyzed except for the iron element. A comparison of the results of the impurities analysis values in Algerian yellow cake by the three separation processes (liquid-liquid extraction (ASTM C761-11), extraction chromatography column, and precipitation) shows the absence of cadmium, titanium, lead, and chromium and the values of the manganese, zinc, and lithium are quite close. The analysis results for the solvent extraction and chromatographic column extraction processes showed that the values of magnesium, copper, and nickel are very close and identical for cobalt. The values of aluminium and iron are close